Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/21/13
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1055 PM MDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 805 PM MDT SAT MAY 18 2013
UPDATED GRIDS TO TAKE DOWN THE RED FLAG WARNING FOR THIS EVENING.
FRONT IS CURRENTLY ACROSS NORTHEAST CO AND IS TIMED BY RUC13 AND
NAM12 TO CROSS THE PALMER DIVIDE BETWEEN 03-05Z. THIS WILL BRING
SOME HIGHER DEW POINT AIR INTO NRN SECTIONS OF THE SE PLAINS WITH
POTENTIAL FOR SOME SHOWERS/ISO TSTORMS TO DEVELOP ACROSS NRN EL
PASO AND POSSIBLY KIOWA COUNTY. HOWEVER 00Z NAM IS KEEPING IT DRY.
WILL CONTINUE TO MONITOR AND MAKE ADJUSTMENTS AS LATEST MODEL RUNS
CONTINUE TO FILTER IN. -KT
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 247 PM MDT SAT MAY 18 2013
NOTE: THIS IS A CORRECTED AFD. THERE ARE NO FIRE WEATHER CONCERNS
FOR TOMORROW. THE ORIGINAL AFD ISSUED AT 247 PM MENTIONED IN THE
HEADLINE "...FIRE WEATHER CONCERNS FOR TOMORROW..."
CURRENTLY
DRYLINE EXTENDS FROM NEAR KAKO TO EXTREME NE KIOWA COUNTY AND THEN
TOWARDS LIBERAL. OVER NEARLY ALL OF OUR PLAINS DWPTS ARE IN THE
TEENS OR LOWER. A STORM HAS RECENTLY DEVELOPED JUST NORTH OF KIOWA
COUNTY AND IS MOVING NNE INTO NW KS. MARGINAL RED FLAG CONDITIONS
WERE OCCURRING OVER S EL PASO COUNTY AS KCOS WAS GUSTING TO 24 KTS
WITH AN RH OF 13%.
REST OF TODAY AND TONIGHT...
VARIABLE HIGH CLOUDS SHOULD EXIST ACROSS THE PLAINS THE REST OF
TODAY WITH WEST WINDS OF 10-20 MPH. WE WILL SEE ISOLD TO SCTD
THUNDER OVER THE MTNS AS THE TROUGH MOVES OVER THE REGION.
A COOL FRONT WILL CROSS THE PLAINS FROM LATE THIS AFTERNOON INTO THE
EVENING. WINDS WILL SHIFT TO THE NORTHWEST AND WILL LIKELY GET A BIT
GUSTY FOR A FEW HOURS. THERE A LOW PROBABILITY OF AN ISOLD TSRA
DEVELOPING WITH THE FROPA...MAINLY OVER EL PASO COUNTY.
OVER THE MTNS FOR TONIGHT WE WILL SEE A CONTINUED THREAT OF ISOLD
SHRA/TSRA...MAINLY OVER THE CONTDVD.
TOMORROW...
SHOULD SEE MOSTLY SUNNY SKIES EARLY IN THE DAY ACROSS THE PLAINS BUT
EXPECT WE WILL CLOUD UP PRETTY QUICKLY GIVEN THE COOL AIR ALOFT OVER
THE REGION. LOTS OF SHOWERS/ISOLD TSRA WILL OCCUR TOMORROW BUT PRECIP
WILL BE QUITE LIGHT OVER THE PLAINS. GUSTY NORTHWEST WINDS OF 15 TO
25 MPH WILL OCCUR NEARLY ALL AREAS BY AFTERNOON. OVER THE MTNS
SHOWERS AND ISOLD TSRA WILL ALSO OCCUR. TEMPS TOMORROW WILL BE A BIT
COOLER THAN TODAY WITH HIGHS MAINLY IN THE 65-75 RANGE...WITH THE
COOLER TEMPS OVER EL PASO COUNTY AND THE WARMEST TEMPS IN BACA
COUNTY. 50S AND 60S WILL OCCUR IN THE MTNS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 247 PM MDT SAT MAY 18 2013
MODELS IN AGREEMENT THROUGH THE EXTENDED WITH LOW ENSEMBLE
SPREADS. THERE ARE SOME DIFFERENCES IN PRECIPITATION TRENDS ACROSS
THE PLAINS...AND THE POSSIBILITY OF THUNDERSTORMS FOR LATE IN THE
WORK WEEK.
SUNDAY NIGHT THROUGH TUESDAY...AN UPPER LEVEL LOW PRESSURE SYSTEM
WILL PARK ITSELF OVER NEBRASKA THROUGH THIS TIME PERIOD. EXPECT
COOLER TEMPERATURES ACROSS THE REGION WITH AFTERNOON HIGHS ON
MONDAY AND TUESDAY IN THE UPPER 60S TO LOWER 70S. ONE MAIN CONCERN
WILL BE THE POTENTIAL FOR FREEZING CONDITIONS OVER THE SAN LUIS
VALLEY SUNDAY...MONDAY AND TUESDAY NIGHTS...WITH OVERNIGHT LOWS
DOWN INTO THE UPPER 20S TO LOWER 30S. THE WET MOUNTAIN VALLEY
SHOULD ALSO BE MONITORED FOR OVERNIGHT LOWS DURING THIS PERIOD AS
WELL. ELSEWHERE OVERNIGHT LOWS WILL BE IN THE UPPER 30S TO MID
40S. AS FAR AS PRECIPITATION IS CONCERNED THERE ARE SOME MODEL
DIFFERENCES. AREAS OVER THE MOUNTAINS WILL LIKELY SEE SHOWER AND
THUNDERSTORM ACTIVITY THROUGH TUESDAY EVENING. COLDER AIR ALOFT IS
EXPECTED TO LOWER SNOW LEVELS DOWN TO AROUND 9-10 KFT AND A FEW
INCHES OF SNOW WILL BE LIKELY ON PEAKS. THERE IS A LITTLE LESS
CERTAINTY ON THE PLAINS. GIVEN THE NORTHWESTERLY FLOW ACROSS THE
REGION...HAVE A FEELING AREAS OVER THE PALMER DIVIDE AND RATON
WILL SEE PERIODS OF SHOWER AND POSSIBLY THUNDERSTORM ACTIVITY
MONDAY AND TUESDAY WHILE AREAS IN THE ARKANSAS VALLEY REMAINED
SHADOWED OUT. FOR NOW THERE ARE SOME LOW POPS IN THE
FORECAST...BUT CONFIDENCE IS LOW AT THIS TIME FOR THE LOWER
ELEVATIONS.
HIGH PRESSURE IS FORECAST TO TRANSIT THE AREA ON WEDNESDAY AS A
STATIONARY LOW SETS UP OVER THE PACIFIC NORTHWEST. THERE MAY BE
ENOUGH INSTABILITY OVER THE MOUNTAINS FOR ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY WEDNESDAY AFTERNOON AND EVENING. AT THE LOW
LEVELS...FLOW TURNS SOUTHEASTERLY WHICH SHOULD BEGIN TO ADVECT
MOISTURE NORTH INTO THE CENTRAL PLAINS. TEMPERATURES WILL ALSO
BEGIN TO WARM WITH HIGHS BACK INTO THE LOWER TO MID 80S.
THURSDAY AND FRIDAY...SOUTHWESTERLY FLOW AROUND A STATIONARY LOW
OVER THE PACIFIC NORTHWEST WILL MOVE INTO COLORADO THURSDAY
THROUGH SATURDAY. THE MAIN CONCERN WILL BE THE POTENTIAL FOR
CONVECTION OVER THE PLAINS. LOW LEVEL SOUTHEASTERLY FLOW WILL
ADVECT MOISTURE NORTHWARD WHILE MIXING OF SOUTHWESTERLY FLOW ALOFT
SHOULD PRODUCE A DRYLINE BOUNDARY EACH AFTERNOON FROM NEAR
COLORADO SPRINGS...SOUTHEAST TO SPRINGFIELD. THE GFS IS INDICATING
QUITE A BIT OF LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY. THE MAIN
ISSUE MAY BE A FORCING MECHANISM. MODELS NOT INDICATING MUCH IN
THE WAY OF SHORTWAVE ACTIVITY LIFTING NORTHEAST ACROSS THE ROCKIES
WHICH MAY LIMIT THE CONVECTIVE POTENTIAL. BOTH DAYS DESERVE
WATCHING. AFTERNOON TEMPERATURES WILL ALSO CONTINUE TO WARM
THROUGH THIS PERIOD WITH 80S ACROSS THE REGION. MOZLEY
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1050 PM MDT SAT MAY 18 2013
UPPER LEVEL TROF WILL MOVE ACROSS SOUTHERN COLORADO OVER THE NEXT
24 HOURS WITH UPPER LOW CLOSING OFF OVER WESTERN NEBRASKA BY 00Z
MONDAY. A COLD FRONT WILL MOVE SOUTH ACROSS THE SOUTHEAST PLAINS
OVERNIGHT WITH WINDS SHIFTING TO THE NORTH. VFR CONDITIONS SHOULD
CONTINUE DURING THE NEXT 24 HOURS. SHOWERS AND THUNDERSTORMS WILL
BE WIDELY SCATTERED AFT 18Z SUNDAY...BUT A RELATIVELY DRY AIRMASS
WILL LIMIT THE AREAL COVERAGE OF SHOWERS AND THUNDERSTORMS SUNDAY
AFTERNOON. STARK
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KT
SHORT TERM...HODANISH
LONG TERM...MOZLEY
AVIATION...STARK
AREA FORECAST DISCUSSION
NWS NEW YORK NY
435 AM EDT SUN MAY 19 2013
.SYNOPSIS...
LOW PRESSURE DEVELOPING OVER QUEBEC WILL TRACK EAST DRAGGING A
WARM FRONT ACROSS THE AREA LATE TONIGHT. THE LOW WILL CONTINUE
ACROSS THE CANADIAN MARITIMES WITH ITS COLD FRONT DROPPING THROUGH
THE AREA ON TUESDAY. THE FRONT THEN REMAINS IN CLOSE PROXIMITY TO
THE AREA BEFORE LIFTING BACK NORTH AS A WARM FRONT ON THURSDAY. A
COLD FRONTAL PASSAGE OCCURS LATE IN THE WEEK OR EARLY WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRES DEVELOPING OVER QUEBEC EARLY THIS MORNING WILL TRACK EWD
TODAY WITH ITS ATTENDING WARM FRONT MOVING THROUGH THE AREA
TONIGHT. MEANWHILE A STATIONARY FRONTAL BOUNDARY EXTENDING FROM
THE MID ATLANTIC STATES TO THE MIDWEST WON`T MOVE MUCH
TODAY...THEN DISSIPATE TONIGHT.
WEAK WAA HAS CAUSED LIGHT RAIN TO LIFT INTO NE NJ AND METRO NY
EARLY THIS MORNING. 00Z MODEL GUIDANCE AS WELL AS HRRR ARE IN GOOD
AGREEMENT AND INDICATE A CLOUDY AND WET DAY AS THIS AREA CONTINUES
TO EXPAND AND GRADUALLY MOVE ACROSS THE AREA. SOME UNCERTAINTY IN TIMING
OF WARM FROPA TONIGHT...SO POPS MAY BE ON THE HIGH SIDE AFTER 06Z
ALTHOUGH INCREASING THETA E WOULD IMPLY ABUNDANT LOW CLOUDS AND
AREAS OF FOG AND DRIZZLE ONCE IT MOVES THROUGH....HIGHS WILL ONLY
REACH THE LOWER TO MID 60S ACROSS THE AREA...WHICH IS 5 TO 10
DEGREES BELOW NORMAL. LOWS TONIGHT WILL BE NEAR TO SLIGHTLY ABOVE
NORMAL LEVELS IN THE MID TO UPPER 50S.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
THE REGION WILL BE WARM SECTORED ON MONDAY AS A COLD FRONT
APPROACHES FROM THE N. EXPECT AT LEAST PARTIAL CLEARING TO
OCCUR...BUT THIS WILL DETERMINE HOW UNSTABLE WE WILL GET. THE
FRONT WILL ALIGN WITH THE FLOW ALOFT WHICH IS RELATIVELY WEAK
(10-20KT) AND COULD LEAD TO TRAINING OF SLOW MOVING THUNDERSTORMS.
PWATS ARE FORECAST TO BE AROUND 1.5 INCHES WHICH IS AROUND 175% OF
NORMAL AND COULD CAUSE SOME MINOR URBAN FLOODING ISSUES. CONFIDENCE
IN ALL OF THIS IS LOW AT THIS TIME.
CONVECTION DIMINISHED MON EVE WITH THE FRONT DROPPING THROUGH THE
AREA. HIGH UNCERTAINTY JUST HOW FAR S THE BOUNDARY GETS...SO HAVE
KEPT THE CHC POPS FOR AFTN SHOWERS AND TSTMS ON TUE...MAINLY N AND
W OF NYC.
TEMPS WILL BE AROUND 5 DEGREES ABOVE NORMAL BOTH MON AND TUE WITH
A NOTICEABLY MORE HUMID AIRMASS IN PLACE AS WELL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
PREDICTABILITY ISSUES DURING THIS TIME PERIOD HAVE TO DO WITH THE
INTERACTION OF EASTERN CANADIAN TROUGHING AND CENTRAL US TROUGHING
THIS WEEK. THE INTERACTION OF THESE TWO ENERGIES WILL DETERMINE THE
MAGNITUDE OF EAST COAST RIDGING FOR THE MIDWEEK. MODELS SIGNALING A
RETURN TO EAST COAST TROUGHING FOR THE WEEKEND AS EAST COAST RIDGING
BUILDS OFFSHORE INTO THE WESTERN ATLANTIC.
SHOWERS AND THUNDERSTORMS COULD CONTINUE TUESDAY NIGHT...WITH
INDICATIONS OF A WAVE OF LOW PRESSURE TRACKING EAST ALONG THE
SAGGING FRONTAL BOUNDARY. MOISTURE POOLING AND STEERING FLOW
PARALLEL TO THE SURFACE BOUNDARY WOULD PRESENT A FLASH FLOOD
THREAT IF THIS PATTERN MATERIALIZED.
THEN FOR THE MID-LATE WEEK PERIOD THE INTERACTION OF THE EARLIER
MENTIONED UPPER FEATURES WILL BE CRITICAL TO THE LOCATION OF THE
FRONTAL BOUNDARY. LATEST GUIDANCE HAS STRONGLY CONVERGED ON THE
BACKDOOR COLD FRONT PUSHING SOUTH THROUGH THE REGION TUESDAY
NIGHT...AND THEN BACK NORTH AS A WARM FRONT ON THURSDAY. IF THE
FRONT DOES PASS SOUTH...ONSHORE FLOW AND CLOUDS WOULD LIKELY DROP
MAX TEMPS TO SEASONABLE OR SLIGHTLY BELOW SEASONABLE LEVELS FOR
WED...SEVERAL DEGREES COOLER THEN FORECASTED.
REGARDLESS OF WHERE THE WARM FRONT ENDS UP...IF THIS BOUNDARY
REMAINS CLOSE TO THE REGION...SHORTWAVES AT THE SOUTHERN EDGE OF THE
WESTERLIES MAY ALLOW FOR CONVECTIVE COMPLEXES TO FORM AND TRACK WEST
TO EAST ALONG THIS BOUNDARY THROUGH THE MID-LATE WEEK PERIOD. ANY
MCS WOULD BRING THE THREAT FOR HEAVY RAIN AND SEVERE WEATHER.
BY THE END OF THE WEEK...MODELS ARE SIGNALING VARYING DEGREES OF
PHASING OF THE MIDWEST UPPER TROUGH AND EASTERN CANADIAN UPPER
TROUGH. THIS WILL HAVE A COLD FRONT PASSING THROUGH THE REGION
SOMETIME FRI INTO SAT...WITH SHOWER AND THUNDERSTORM ACTIVITY
FINALLY EXITING IN IT WAKE. DEGREE OF PHASING OF UPPER ENERGIES WILL
DETERMINE TIMING AND ACTIVITY ALONG THE FRONT.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE PASSES TO THE EAST TODAY AS A FRONTAL BOUNDARY
REMAINS TO THE SOUTH.
CEILINGS MAY BOUNCE AROUND FROM MVFR TO VFR THIS MORNING...AND
TRENDS WILL NEED TO BE WATCHED. DO EXPECT ON AND OFF LIGHT RAIN
THIS MORNING FOR MOST TERMINALS. KGON MAY NOT SEE RAIN UNTIL THIS
AFTERNOON.
PLEASE SEE INDIVIDUAL TERMINAL FORECASTS FOR SPECIFICS AND BEST
DETERMINISTIC FORECASTS...BUT MVFR CEILINGS LIKELY PREVAIL THROUGH
MUCH OF THE AFTERNOON WITH A LOWER PROBABILITY OF CEILINGS UNDER
1 KFT.
DO EXPECT IFR OR LOWER CIGS/VSBYS BY EVENING.
WINDS GENERALLY SOUTHEAST...WITH HIGHER SUSTAINED WINDS DURING THE
DAYTIME HOURS.
.OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...
.TONIGHT...IFR OR LIFR CONDITIONS...IN PERIODS OF LIGHT RAIN AND
FOG.
.MONDAY...IMPROVEMENT TO VFR BY MID TO LATE MORNING. SCATTERED
SHOWERS...AND ISOLATED THUNDERSTORMS WITH BRIEF MVFR CONDS POSSIBLE
IN THE AFTERNOON.
.MONDAY NIGHT...MVFR OR LOWER CONDITIONS LIKELY WITH LOW CLOUDS AND
FOG.
.TUESDAY-THURSDAY...CHANCE OF MVFR OF LOWER CONDITIONS IN SHOWERS
AND THUNDERSTORMS.
&&
.MARINE...
HIGH PRESSURE PASSES EAST OF THE WATERS TODAY. AS IT DOES
SO...SOUTHERLY WINDS WILL INCREASE TO AROUND 20 KTS...MAINLY ACROSS
THE OCEAN WATERS.
BY TONIGHT...LOW PRESSURE PASSES TO THE NORTH OF THE WATERS. WINDS
TURN TOWARD THE SOUTHWEST THROUGH MONDAY. A FRONTAL BOUNDARY
APPROACHES FROM THE NORTH BY TUESDAY...AND WINDS LIGHTEN AND COULD
SHIFT AROUND TO THE NORTHEAST OR EAST DEPENDING ON HOW FAR SOUTH
THE FRONT MOVES.
EVENTUALLY THIS FRONT IS EXPECTED TO MOVE BACK TO THE NORTH
RESULTING IN A WIND SHIFT TO THE SOUTH ONCE AGAIN BY MID WEEK.
WAVE WATCH HAS BEEN RUNNING HIGH...BUT LATEST GUIDANCE HAS CAPTURED THE
TRENDS AND SLOWLY BUILDS SEAS TODAY. MAY UNDERCUT OCEAN SEA FCSTS
SLIGHTLY EARLY IN THE WEEK...BUT SEAS REMAIN RATHER ROUGH THROUGH
MONDAY ON THE OCEAN WATERS DUE TO PERSISTENT SOUTHERLY FETCH AND
SWELLS.
WILL FOLLOW WIND DIRECTION AND SPEED CLIMATOLOGY FOR SEA/WAVE FCSTS
ACROSS LI SOUND AND THE SURROUNDING HARBORS AND BAYS.
&&
.HYDROLOGY...
UP TO 1/4 INCH OF RAINFALL IS EXPECTED THROUGH TONIGHT.
PERIODS OF SHOWERS AND THUNDERSTORMS ARE POSSIBLE MON THROUGH
FRI...WHICH WOULD BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL.
THERE IS CURRENTLY A LOW THREAT OF FLASH FLOODING FROM ORGANIZED
SHOWER THUNDERSTORM ACTIVITY DURING THIS TIME PERIOD.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT MONDAY FOR ANZ353-355.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT MONDAY FOR
ANZ350.
&&
$$
AREA FORECAST DISCUSSION
NWS NEW YORK NY
359 AM EDT SUN MAY 19 2013
.SYNOPSIS...
LOW PRESSURE DEVELOPING OVER QUEBEC WILL TRACK EAST DRAGGING A
WARM FRONT ACROSS THE AREA LATE TONIGHT. THE LOW WILL CONTINUE
ACROSS THE CANADIAN MARITIMES WITH ITS COLD FRONT DROPPING THROUGH
THE AREA ON TUESDAY. THE FRONT THEN REMAINS IN CLOSE PROXIMITY TO
THE AREA BEFORE LIFTING BACK NORTH AS A WARM FRONT ON THURSDAY. A
COLD FRONTAL PASSAGE OCCURS LATE IN THE WEEK OR EARLY WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRES DEVELOPING OVER QUEBEC EARLY THIS MORNING WILL TRACK EWD
TODAY WITH ITS ATTENDING WARM FRONT MOVING THROUGH THE AREA
TONIGHT. MEANWHILE A STATIONARY FRONTAL BOUNDARY EXTENDING FROM
THE MID ATLANTIC STATES TO THE MIDWEST WON`T MOVE MUCH
TODAY...THEN DISSIPATE TONIGHT.
WEAK WAA HAS CAUSED LIGHT RAIN TO LIFT INTO NE NJ AND METRO NY
EARLY THIS MORNING. 00Z MODEL GUIDANCE AS WELL AS HRRR ARE IN GOOD
AGREEMENT AND INDICATE A CLOUDY AND WET DAY AS THIS AREA CONTINUES
TO EXPAND AND GRADUALLY MOVE ACROSS THE AREA. SOME UNCERTAINTY IN TIMING
OF WARM FROPA TONIGHT...SO POPS MAY BE ON THE HIGH SIDE AFTER 06Z
ALTHOUGH INCREASING THETA E WOULD IMPLY ABUNDANT LOW CLOUDS AND
AREAS OF FOG AND DRIZZLE ONCE IT MOVES THROUGH....HIGHS WILL ONLY
REACH THE LOWER TO MID 60S ACROSS THE AREA...WHICH IS 5 TO 10
DEGREES BELOW NORMAL. LOWS TONIGHT WILL BE NEAR TO SLIGHTLY ABOVE
NORMAL LEVELS IN THE MID TO UPPER 50S.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
THE REGION WILL BE WARM SECTORED ON MONDAY AS A COLD FRONT
APPROACHES FROM THE N. EXPECT AT LEAST PARTIAL CLEARING TO
OCCUR...BUT THIS WILL DETERMINE HOW UNSTABLE WE WILL GET. THE
FRONT WILL ALIGN WITH THE FLOW ALOFT WHICH IS RELATIVELY WEAK
(10-20KT) AND COULD LEAD TO TRAINING OF SLOW MOVING THUNDERSTORMS.
PWATS ARE FORECAST TO BE AROUND 1.5 INCHES WHICH IS AROUND 175% OF
NORMAL AND COULD CAUSE SOME MINOR URBAN FLOODING ISSUES. CONFIDENCE
IN ALL OF THIS IS LOW AT THIS TIME.
CONVECTION DIMINISHED MON EVE WITH THE FRONT DROPPING THROUGH THE
AREA. HIGH UNCERTAINTY JUST HOW FAR S THE BOUNDARY GETS...SO HAVE
KEPT THE CHC POPS FOR AFTN SHOWERS AND TSTMS ON TUE...MAINLY N AND
W OF NYC.
TEMPS WILL BE AROUND 5 DEGREES ABOVE NORMAL BOTH MON AND TUE WITH
A NOTICEABLY MORE HUMID AIRMASS IN PLACE AS WELL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
PREDICTABILITY ISSUES DURING THIS TIME PERIOD HAVE TO DO WITH THE
INTERACTION OF EASTERN CANADIAN TROUGHING AND CENTRAL US TROUGHING
THIS WEEK. THE INTERACTION OF THESE TWO ENERGIES WILL DETERMINE THE
MAGNITUDE OF EAST COAST RIDGING FOR THE MIDWEEK. MODELS SIGNALING A
RETURN TO EAST COAST TROUGHING FOR THE WEEKEND AS EAST COAST RIDGING
BUILDS OFFSHORE INTO THE WESTERN ATLANTIC.
SHOWERS AND THUNDERSTORMS COULD CONTINUE TUESDAY NIGHT...WITH
INDICATIONS OF A WAVE OF LOW PRESSURE TRACKING EAST ALONG THE
SAGGING FRONTAL BOUNDARY. MOISTURE POOLING AND STEERING FLOW
PARALLEL TO THE SURFACE BOUNDARY WOULD PRESENT A FLASH FLOOD
THREAT IF THIS PATTERN MATERIALIZED.
THEN FOR THE MID-LATE WEEK PERIOD THE INTERACTION OF THE EARLIER
MENTIONED UPPER FEATURES WILL BE CRITICAL TO THE LOCATION OF THE
FRONTAL BOUNDARY. LATEST GUIDANCE HAS STRONGLY CONVERGED ON THE
BACKDOOR COLD FRONT PUSHING SOUTH THROUGH THE REGION TUESDAY
NIGHT...AND THEN BACK NORTH AS A WARM FRONT ON THURSDAY. IF THE
FRONT DOES PASS SOUTH...ONSHORE FLOW AND CLOUDS WOULD LIKELY DROP
MAX TEMPS TO SEASONABLE OR SLIGHTLY BELOW SEASONABLE LEVELS FOR
WED...SEVERAL DEGREES COOLER THEN FORECASTED.
REGARDLESS OF WHERE THE WARM FRONT ENDS UP...IF THIS BOUNDARY
REMAINS CLOSE TO THE REGION...SHORTWAVES AT THE SOUTHERN EDGE OF THE
WESTERLIES MAY ALLOW FOR CONVECTIVE COMPLEXES TO FORM AND TRACK WEST
TO EAST ALONG THIS BOUNDARY THROUGH THE MID-LATE WEEK PERIOD. ANY
MCS WOULD BRING THE THREAT FOR HEAVY RAIN AND SEVERE WEATHER.
BY THE END OF THE WEEK...MODELS ARE SIGNALING VARYING DEGREES OF
PHASING OF THE MIDWEST UPPER TROUGH AND EASTERN CANADIAN UPPER
TROUGH. THIS WILL HAVE A COLD FRONT PASSING THROUGH THE REGION
SOMETIME FRI INTO SAT...WITH SHOWER AND THUNDERSTORM ACTIVITY
FINALLY EXITING IN IT WAKE. DEGREE OF PHASING OF UPPER ENERGIES WILL
DETERMINE TIMING AND ACTIVITY ALONG THE FRONT.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE PASSES TO THE EAST TODAY AS A FRONTAL BOUNDARY
REMAINS TO THE SOUTH.
EXPECT CEILINGS TO LOWER THIS MORNING...WITH LIGHT RAIN DEVELOPING
ACROSS NYC METRO...EVENTUALLY EXPANDING EAST. KGON MAY NOT SEE
RAIN UNTIL LATE THIS AFTERNOON.
PLEASE SEE INDIVIDUAL TERMINAL FORECASTS FOR SPECIFICS AND BEST
DETERMINISTIC FORECASTS...BUT MVFR CEILINGS LIKELY PREVAIL THROUGH
MUCH OF THE DAY WITH A LOWER PROBABILITY OF CEILINGS UNDER 1 KFT.
DO EXPECT IFR OR LOWER CIGS/VSBYS BY EVENING.
WINDS GENERALLY SOUTHEAST...WITH HIGHER SUSTAINED WINDS DURING THE
DAYTIME HOURS.
.OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...
.TONIGHT...IFR OR LIFR CONDITIONS...IN ON AND OFF LIGHT RAIN AND
FOG.
.MONDAY...IMPROVEMENT TO VFR BY MID TO LATE MORNING. SCATTERED
SHOWERS...AND ISOLATED THUNDERSTORMS WITH BRIEF MVFR CONDS POSSIBLE
IN THE AFTERNOON.
.MONDAY NIGHT...MVFR OR LOWER CONDITIONS LIKELY WITH LOW CLOUDS AND
FOG.
.TUESDAY-THURSDAY...CHANCE OF MVFR OF LOWER CONDITIONS IN SHOWERS
AND THUNDERSTORMS.
&&
.MARINE...
HIGH PRESSURE PASSES EAST OF THE WATERS TODAY. AS IT DOES
SO...SOUTHERLY WINDS WILL INCREASE TO AROUND 20 KTS...MAINLY ACROSS
THE OCEAN WATERS.
BY TONIGHT...LOW PRESSURE PASSES TO THE NORTH OF THE WATERS. WINDS
TURN TOWARD THE SOUTHWEST THROUGH MONDAY. A FRONTAL BOUNDARY
APPROACHES FROM THE NORTH BY TUESDAY...AND WINDS LIGHTEN AND COULD
SHIFT AROUND TO THE NORTHEAST OR EAST DEPENDING ON HOW FAR SOUTH
THE FRONT MOVES.
EVENTUALLY THIS FRONT IS EXPECTED TO MOVE BACK TO THE NORTH
RESULTING IN A WIND SHIFT TO THE SOUTH ONCE AGAIN BY MID WEEK.
WAVE WATCH HAS BEEN RUNNING HIGH...BUT LATEST GUIDANCE HAS CAPTURED THE
TRENDS AND SLOWLY BUILDS SEAS TODAY. MAY UNDERCUT OCEAN SEA FCSTS
SLIGHTLY EARLY IN THE WEEK...BUT SEAS REMAIN RATHER ROUGH THROUGH
MONDAY ON THE OCEAN WATERS DUE TO PERSISTENT SOUTHERLY FETCH AND
SWELLS.
WILL FOLLOW WIND DIRECTION AND SPEED CLIMATOLOGY FOR SEA/WAVE FCSTS
ACROSS LI SOUND AND THE SURROUNDING HARBORS AND BAYS.
&&
.HYDROLOGY...
UP TO 1/4 INCH OF RAINFALL IS EXPECTED THROUGH TONIGHT.
PERIODS OF SHOWERS AND THUNDERSTORMS ARE POSSIBLE MON THROUGH
FRI...WHICH WOULD BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL.
THERE IS CURRENTLY A LOW THREAT OF FLASH FLOODING FROM ORGANIZED
SHOWER THUNDERSTORM ACTIVITY DURING THIS TIME PERIOD.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT MONDAY FOR ANZ353-355.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT MONDAY FOR
ANZ350.
&&
$$
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1228 PM EDT SUN MAY 19 2013
.SYNOPSIS...
A FRONTAL BOUNDARY TO OUR SOUTH IS EXPECTED TO WEAKEN AND
DISSIPATE AS IT REMAINS NEARLY STATIONARY THROUGH MONDAY. MEANWHILE,
HIGH PRESSURE SHOULD REMAIN TO OUR NORTHEAST AND EAST. ANOTHER
FRONTAL BOUNDARY FROM THE NORTH IS FORECAST TO DROP INTO OUR
REGION LATE ON TUESDAY AND IT SHOULD LIFT BACK TO THE NORTH ON
WEDNESDAY AND THURSDAY. A COLD FRONT FROM THE WEST IS THEN EXPECTED
TO ARRIVE ON FRIDAY, FOLLOWED BY HIGH PRESSURE FOR SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE ONSHORE LOW LEVEL FLOW WILL CONTINUE THIS AFTERNOON WITH A
WEALTH OF LOW LEVEL CLOUDINESS EXPECTED. AN AREA OF SHOWERS
PRESENTLY OVER ERN NJ WILL CONTINUE THROUGH EARLY AFTERNOON
BEFORE MOVING OFF TO THE EAST. SOME SHOWERS ARE EXPECTED TO
DEVELOP ACROSS THE SRN AREAS AND MOVE OVER THE AREA LATER TODAY.
THE LATEST HRRR AND NAM RUNS HOWEVER HAVE LIMITED COVERAGE OF
THESE SHOWERS AND HAVE REDUCED POPS TO HIGH CHANCE. IF A FEW
BREAKS IN THE CLOUDS DEVELOP ACROSS THE DELMARVA...A FEW POP-UP
TSTMS MAY OCCUR. THE POSSIBILITY OF THIS LOOKS LOW ENOUGH ATTM TO
KEEP OUT OF THE FCST.
TEMPERATURES WILL REMAIN IN CHECK...WITH THE ABUNDANCE OF CLOUDS.
READINGS IN THE MID/UPPER 60S ACROSS THE NRN AREAS AND UPPER 60S
TO LOW 70S OVER THE SRN AREAS. WINDS WILL BE EAST/SOUTHEAST AT 5
TO 10 MPH MUCH OF THE AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
THE AFOREMENTIONED MID LEVEL FEATURE LOOKS TO LINGER NEAR THE MID
ATLANTIC TONIGHT, AS A RIDGE ALOFT GRADUALLY SLIDES EASTWARD. HIGH
PRESSURE AT THE SURFACE AS A RESULT IS FORECAST TO SLIDE FARTHER
TO OUR EAST, WHICH WILL ALLOW THE LOW-LEVEL FLOW TO VEER FROM
SOUTHEAST TO MORE SOUTH OR SOUTHWEST OVERNIGHT. THIS MAINTAINS
THETA-E ADVECTION THROUGH THE NIGHT WITH AT LEAST SOME WAA AS
WELL. THERE DOES NOT APPEAR TO BE MUCH IN THE WAY OF ORGANIZED
LIFT MOVING THROUGH, THEREFORE THE SHOWERS DURING THE DAY SHOULD
DECREASE IN AREAL COVERAGE.
HOWEVER, AS THE FLOW VEERS AND MOISTURE INCREASES IN THE LOWER
LEVELS SOME MODEL GUIDANCE INDICATES THAT THIS MOISTURE GENERALLY
BECOMES LOCKED IN THE LOWEST LEVELS. IF ENOUGH DRYING CAN OCCUR
ABOVE THIS, THEN SOME DRIZZLE MAY BE THE MAIN PRECIPITATION TYPE
DURING THE COURSE OF THE NIGHT. THIS COULD BE MAINLY FOR OUR
CENTRAL AND NORTHERN ZONES, AS FARTHER SOUTH ENOUGH WARMING MAY
RESULT IN THE CLOUD BASES RISING SOME AND A LESS CONDUCIVE SETUP
FOR DRIZZLE. WE NOTICED THAT SOME OF THE HIGH RESOLUTION GUIDANCE
INDICATES LITTLE TO NO PRECIPITATION OCCURRING DURING THE NIGHT,
WITH PERHAPS SOME SHOWERS DEVELOPING TOWARD DAYBREAK AS SOME
PVA/LIFT ARRIVES FROM THE SOUTHWEST WITH THE MID LEVEL FEATURE. AS
A RESULT, WE LOWERED POPS INTO THE CHC RANGE AND CARRIED SHOWERS
FAR SOUTH WITH LIGHT RAIN/DRIZZLE FARTHER NORTH. WE ALSO ADDED IN
PATCHY FOG, FIRST STARTING IN THE HIGHER TERRAIN THEN TO OTHER
AREAS.
AS FOR LOW TEMPERATURES, WE MAINLY USED AN EVEN GFS/NAM MOS
BLEND. TEMPERATURES SHOULD BE ON THE MILD SIDE GIVEN THE CLOUDS
AND CONTINUED WAA. THERE IS A CHC THAT ESPECIALLY THE FAR SOUTHERN
AREAS HAVE SOME INCREASE IN THE TEMPERATURES OVERNIGHT.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
THE MID LEVEL PATTERN IS EXPECTED TO FEATURE THE POLAR VORTEX WELL
TO OUR NORTHEAST WITH A CLOSED LOW OVER THE MIDDLE MISSOURI RIVER
VALLEY ON MONDAY. THERE SHOULD BE A RIDGE EXTENDING FROM THE
SOUTHEASTERN STATES TO THE GREAT LAKES. THE POLAR VORTEX WILL
REMAIN THE DOMINANT FEATURE OVER EASTERN CANADA DURING THE NEW
WEEK. MEANWHILE, THE CLOSED LOW TO OUR WEST AND ITS ASSOCIATED
TROUGH WILL PROGRESS EASTWARD, GRADUALLY SQUEEZING THE RIDGE AND
PUSHING IT OUT OVER THE ATLANTIC. AS THE TROUGH BEGINS TO MOVE
TOWARD THE EASTERN STATES, IT SHOULD START TO INTERACT WITH THE
POLAR VORTEX AROUND WEDNESDAY AS THAT FEATURE`S INFLUENCE BEGINS
TO EXPAND TO THE WEST AND SOUTH. THE RESULTING MID LEVEL TROUGH
WILL LIKELY MOVE EASTWARD ACROSS THE GREAT LAKES AND THE
NORTHEASTERN STATES IN THE THURSDAY THROUGH SATURDAY TIME FRAME.
THE SURFACE FLOW IS FORECAST TO VEER TO THE SOUTH AND SOUTHWEST
FOR MONDAY AND MONDAY NIGHT CAUSING THE CLOUDS TO LIFT AND
TEMPERATURES TO WARM, RESULTING IN THE DEVELOPMENT OF UNSTABLE
CONDITIONS, ESPECIALLY AWAY FROM THE OCEAN. SURFACE BASED CAPE
VALUES ARE ANTICIPATED TO RISE NEAR 1000 J/KG IN OUR WESTERN
COUNTIES DURING THE AFTERNOON. A FAIR AMOUNT OF LOW LEVEL MOISTURE
WILL REMAIN IN OUR REGION. AS A RESULT, WE WILL CONTINUE TO
MENTION A CHANCE OF SHOWERS FOR MONDAY AND WE WILL ALSO INCLUDE
THE POTENTIAL FOR AFTERNOON THUNDERSTORMS. THE GUIDANCE IS
INDICATING A DECREASE IN PRECIPITATION FOR MONDAY NIGHT WITH THE
LOSS OF DAYTIME HEATING AND WITH THE LACK OF ANY FOCUSING
MECHANISM.
TEMPERATURES ARE FORECAST TO RISE NEAR +15C AT 850 HPA FOR
TUESDAY. A SOUTH TO SOUTHWEST SURFACE FLOW WILL CONTINUE AND
TEMPERATURES ARE EXPECTED TO RISE INTO THE LOWER AND MIDDLE 80S IN
MUCH OF OUR FORECAST AREA. LINGERING LOW LEVEL MOISTURE WILL HELP
ENHANCE THE INSTABILITY AND WE ARE ANTICIPATING SCATTERED SHOWERS
AND THUNDERSTORMS, ESPECIALLY IN THE AFTERNOON AND EVENING.
SURFACE BASED CAPE VALUES IN THE 1500 J/KG NEIGHBORHOOD ARE
POSSIBLE IN OUR SOUTHWESTERN COUNTIES. THE MOST UNSTABLE AREAS
WILL LIKELY HAVE PRECIPITABLE WATER VALUES IN EXCESS OF 1.5 INCHES
WITH THERE BEING THE POTENTIAL FOR LOCALIZED DOWNPOURS.
A FRONTAL BOUNDARY IS FORECAST TO DROP INTO OUR REGION FROM THE
NORTH LATE ON TUESDAY. THERE IS A FAIR AMOUNT OF UNCERTAINTY AS TO
HOW FAR SOUTH THE BOUNDARY WILL PROGRESS. IT SHOULD CONTINUE TO
HAVE A LEAST A LITTLE MOMENTUM INTO WEDNESDAY. HOWEVER, AS THE MID
LEVEL RIDGE AXIS PASSES OVERHEAD ON WEDNESDAY OR WEDNESDAY NIGHT,
THE BOUNDARY IS EXPECTED TO BEGIN LIFTING BACK TO THE NORTH.
REGARDLESS, UNSETTLED CONDITIONS WILL LIKELY CONTINUE.
AS THE MID LEVEL TROUGH BEGINS TO INFLUENCE OUR REGION LATE IN
THE WEEK IT SHOULD MOVE A COLD FRONT ACROSS THE NORTHEASTERN
STATES ON FRIDAY. AS A RESULT, WE WILL CARRY A CHANCE OF SHOWERS
AND AFTERNOON THUNDERSTORMS FOR FRIDAY.
WHILE THERE WILL BE A CHANCE OF PRECIPITATION IN THE FORECAST FOR
EACH DAY FROM MONDAY THROUGH FRIDAY, THE WEEK SHOULD NOT BE A
TOTAL WASHOUT. ACTUALLY, MOST OF THE TIME PRECIPITATION WILL NOT
BE FALLING. OVERALL, TEMPERATURES FOR THE WEEK SHOULD AVERAGE
ABOVE NORMAL FOR THIS TIME OF THE YEAR.
AFTER THE COLD FRONT PASSES, DRY AIR IS ANTICIPATED TO BEGIN
BUILDING INTO OUR REGION FROM THE NORTHWEST AND NORTH FOR FRIDAY
NIGHT AND SATURDAY.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...MVFR/IFR CEILINGS PREVAIL THROUGH THE DAY, AND THERE IS
LOWER CONFIDENCE REGARDING ANY IMPROVEMENTS. IT IS POSSIBLE THAT
TERMINALS WITH IFR CEILINGS IMPROVE TO MVFR IN THE AFTERNOON, AND
THE VISIBILITIES SHOULD BE MOSTLY DEPENDENT ON THE SHOWERS.
SOUTHEAST WINDS GENERALLY NEAR 10 KNOTS.
TONIGHT...IFR CEILINGS, WITH A CHANCE FOR IMPROVEMENT TO MVFR
AT TIMES MAINLY SOUTH AND EAST OF KILG. OVERALL, SOME SHOWERS
SHOULD BE AROUND ESPECIALLY IN THE EVENING WITH EVEN THIS PERHAPS
TRANSITIONING TO SOME DRIZZLE, THEREFORE TIMES OF LOCAL VISIBILITY
RESTRICTIONS SHOULD OCCUR. SOME FOG IS ANTICIPATED WHICH WILL ALSO
LOWER THE LOCAL VISIBILITY, ALTHOUGH WE ARE CURRENTLY NOT
ANTICIPATING FOG TO REDUCE THE VISIBILITY TO UNDER 1SM. SOUTHEAST
WINDS 4-8 KNOTS, SHOULD TURN MORE SOUTH-SOUTHWEST.
OUTLOOK...
MONDAY THROUGH THURSDAY...MAINLY VFR. HOWEVER, MVFR AND IFR
CONDITIONS ARE POSSIBLE ESPECIALLY DURING THE LATE NIGHT AND EARLY
MORNING HOURS EACH DAY. ALSO, THERE WILL BE A CHANCE OF SHOWERS
AND THUNDERSTORMS THROUGH THE PERIOD WHICH COULD LOWER CEILINGS
AND REDUCE THE VISIBILITY AT TIMES.
&&
.MARINE...
HIGH PRESSURE REMAINING TO OUR NORTHEAST TODAY WILL MAINTAIN A
SOUTHEASTERLY FLOW, ALTHOUGH THIS SHOULD START TO TURN MORE FROM
THE SOUTH LATER TODAY ACROSS THE SOUTHERN WATERS. THIS SHIFT TO
SOUTHERLY SHOULD THEN OVERSPREAD ALL THE WATERS TONIGHT. THIS FLOW
REGIME, WHICH IS ANTICIPATED TO REMAIN UNDER 25 KNOTS, WILL ALLOW
THE SEAS TO BUILD SOME MORE THOUGH. THE WAVEWATCH GUIDANCE HAS
BEEN RUNNING 1-2 FEET TO HIGH, HOWEVER IT IS CATCHING UP AS SEAS
REACHED 5 FEET EARLIER AT BUOY 44009. THESE HIGHER SEAS ARE
ANTICIPATED TO SPREAD NORTHWARD TODAY, HOWEVER CONFIDENCE IS NOT
ALL THAT HIGH THEY GET ABOVE 6 FEET. THEREFORE, THE SMALL CRAFT
ADVISORY REMAINS IN EFFECT FOR OUR OCEAN ZONES THROUGH TONIGHT.
THE CONDITIONS ARE ANTICIPATED TO REMAIN BELOW ADVISORY CRITERIA
ON DELAWARE BAY. SOME ADDITIONAL INCREASE IN THE DEW POINTS
TONIGHT COULD RESULT IN SOME FOG DEVELOPMENT.
OUTLOOK...
HIGH PRESSURE TO OUR NORTHEAST AND EAST WILL CONTINUE TO
INFLUENCE THE COASTAL WATERS OF NEW JERSEY AND DELAWARE INTO
TUESDAY. A FRONTAL BOUNDARY FROM THE NORTH IS FORECAST TO DROP
INTO OUR REGION ON TUESDAY NIGHT BEFORE RETREATING BACK TO THE
NORTH ON WEDNESDAY AND THURSDAY.
WIND SPEEDS ARE FORECAST TO REMAIN LESS THAN 25 KNOTS FROM MONDAY
THROUGH THURSDAY. WAVE HEIGHTS ON OUR OCEAN WATERS COULD REMAIN
AROUND 5 FEET ON MONDAY INTO MONDAY NIGHT AND THE CURRENT SMALL
CRAFT ADVISORY MAY NEED TO BE EXTENDED TO COVER THAT PERIOD. A
LULL IN WAVE HEIGHTS IS POSSIBLE FOR TUESDAY AND WEDNESDAY WITH 5
FOOT SEAS FORECAST TO RETURN TO OUR OCEAN WATERS FOR THURSDAY AS A
LONG SOUTHERLY FETCH BECOMES ESTABLISHED ALONG THE EAST COAST.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ450>455.
&&
$$
SYNOPSIS...IOVINO
NEAR TERM...GAINES/GORSE/O`HARA
SHORT TERM...GORSE
LONG TERM...IOVINO
AVIATION...GORSE/IOVINO
MARINE...GORSE/IOVINO
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
312 PM EDT SUN MAY 19 2013
.SHORT TERM /TONIGHT THROUGH MONDAY/...
A RATHER MESSY UPPER LEVEL SYSTEM CONTINUES TO KEEP THE RISK OF
THUNDERSTORMS WITH HEAVY RAIN OVER MUCH OF THE CWA LATE THIS
AFTERNOON. REDEVELOPMENT OF THUNDERSTORMS ACROSS EASTERN TN/NORTH
GA IS REINFORCING THE FORECAST BY THE HRRR WHICH BRINGS ANOTHER
ROUND OT THUNDERSTORMS DOWN THE WEST SIDE OF GA THROUGH 00Z. THIS
WILL ALSO KEEP THE RISK OF FLASH FLOODING OVER THE WATCH AREA
THROUGH 00Z. THE PRECIP WILL SLOWLY EXIT FROM THE WEST TONIGHT
ALTHOUGH SOUTHEAST/EAST GA WILL STILL SEE SCATTERED
SHOWERS/TSTORMS INTO MONDAY. BY MONDAY AFTERNOON HIGH PRESSURE
WILL BE BUILDING OVER AL/GA WHICH SHOULD ALSO STABILIZE THE
ATMOSPHERE ENDING THE PRECIP BY MONDAY NIGHT/TUESDAY. MAV/MET
TEMPS LOOKING ALRIGHT...PERHAPS ON THE COOL SIDE TONIGHT AND HAVE
RAISE THEM A DEGREE OR TWO. WITH MORE SUNSHINE MONDAY
AFTERNOON...EXPECT TEMPS TO RISE WELL INTO THE 80S MOST AREAS.
17
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
VERY FEW CHANGES TO THE EXTENDED. MADE SOME ADJUSTMENTS TO TEMPS
ON SATURDAY TO ACCOUNT FOR DRY CAD PROGGED TO DEVELOP. 12Z RUNS OF
GFS AND ECMWF STILL SIMILAR FOR THE SYSTEM AT THE END OF THE WEEK WITH
VERY LITTLE PRECIP EXPECTED AND THE FRONT MOVING THROUGH SOMETIME
EARLY FRIDAY. ALSO INCREASED CLOUD COVER A LITTLE FOR THE
WEDNESDAY SYSTEM AND ADJUSTED TEMPS ACCORDINGLY THERE AS
WELL...OTHERWISE NO SIGNIFICANT CHANGES.
TDP
PREV DISCUSSION... /ISSUED 357 AM EDT SUN MAY 19 2013/
PRECIP SHOULD END FROM WEST TO EAST TONIGHT AS THE SHORTWAVE
TROUGH SETS UP ALONG THE EASTERN SEABOARD. HAVE ONLY TWEAKED POPS
DURING THIS PERIOD.
FOR THE FIRST PART OF THE WEEK...THE 500MB TROUGH/SHEAR AXIS REMAINS
ACROSS THE SE COAST. THIS FEATURE WILL HELP FOCUS SCT DIURNAL
CONVECTION EACH DAY. PREVIOUS RUNS PUSHED THE FEATURE OFF THE COAST
ON TUESDAY...BUT IT SHOULD REMAIN IN PLACE UNTIL EARLY WEDNESDAY.
FOR THE LATTER PART OF THE WEEK...A COLD FRONT IS EXPECTED TO MOVE
INTO THE SOUTHEAST STATES. MODEL RUN TO RUN CONSISTENCY FOR THIS
FEATURE HAS BEEN LOW FOR THE PAST FEW DAYS. THE ECMWF NOW HAS THE
BOUNDARY APPROACHING NORTHERN GA ON FRIDAY...AND MOVING THROUGH THE
CWFA DURING THE DAY. THE GFS HAS CONTINUES TO BRING THE BOUNDARY
SOUTHWARD. NEITHER MODEL IS PRODUCING MUCH PRECIP WITH THIS FEATURE
FOR NOW...SO WILL LEAVE POPS IN THE SCT RANGE.
HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
MAIN CHANGES TO THE EXTENDED WERE TO UP POPS SLIGHTLY IN THE EAST
FOR WEDNESDAY. MAINLY PERSISTENCE FOR THE LATTER HALF OF WEEK.
NLISTEMAA
&&
.AVIATION...
18Z UPDATE...
REDEVELOPMENT OF CONVECTION OVER NORTHEAST AND EAST CENTRAL ALABAMA
WILL KEEP THE RISK OF THUNDER THROUGH THE AFTERNOON. CONVECTION WILL
DIMINISH THIS EVENING WITH STRATUS/STRATO CU FORMING LATE TONIGHT
WITH CIGS DROPPING TO MVFR/IFR. ALL AREAS SHOULD RISE TO VFR BY 18Z
MONDAY. WINDS WILL BE SOUTH SOUTHWEST LESS THAN 10 KTS...THEN LIGHT
AND VARIABLE TONIGHT...THEN SOUTH SOUTHWEST MONDAY.
//ATL CONFIDENCE...12Z UPDATE...
LOW CONFIDENCE ON CIGS AND TIMING OF SHRA/TSRA.
MEDIUM CONFIDENCE REMAINDER OF ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 63 86 65 86 / 50 20 10 30
ATLANTA 66 86 67 85 / 40 10 10 30
BLAIRSVILLE 60 83 60 82 / 40 10 10 40
CARTERSVILLE 63 87 65 87 / 30 10 10 20
COLUMBUS 66 89 67 89 / 60 10 10 10
GAINESVILLE 63 83 65 83 / 40 10 10 40
MACON 66 87 65 88 / 70 20 20 20
ROME 63 88 64 87 / 30 10 10 20
PEACHTREE CITY 64 86 65 86 / 50 10 10 20
VIDALIA 68 88 67 87 / 70 50 40 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
SEVERE THUNDERSTORM WATCH UNTIL 7 PM EDT THIS EVENING FOR THE
FOLLOWING ZONES: BIBB...BLECKLEY...CHATTAHOOCHEE...CRAWFORD...
CRISP...DODGE...DOOLY...HARRIS...HOUSTON...JOHNSON...LAURENS...
MACON...MARION...MONTGOMERY...MUSCOGEE...PEACH...PULASKI...
SCHLEY...STEWART...SUMTER...TALBOT...TAYLOR...TELFAIR...TOOMBS...
TREUTLEN...TWIGGS...UPSON...WEBSTER...WHEELER...WILCOX...
WILKINSON.
FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES:
BALDWIN...BANKS...BARROW...BARTOW...BIBB...BUTTS...CARROLL...
CATOOSA...CHATTOOGA...CHEROKEE...CLARKE...CLAYTON...COBB...
COWETA...CRAWFORD...DADE...DAWSON...DEKALB...DOUGLAS...FANNIN...
FAYETTE...FLOYD...FORSYTH...GILMER...GLASCOCK...GORDON...
GREENE...GWINNETT...HALL...HANCOCK...HARALSON...HEARD...HENRY...
JACKSON...JASPER...JEFFERSON...JONES...LAMAR...LUMPKIN...
MADISON...MERIWETHER...MONROE...MORGAN...MURRAY...NEWTON...NORTH
FULTON...OCONEE...OGLETHORPE...PAULDING...PICKENS...PIKE...
POLK...PUTNAM...ROCKDALE...SOUTH FULTON...SPALDING...
TALIAFERRO...TOWNS...TROUP...UNION...UPSON...WALKER...WALTON...
WARREN...WASHINGTON...WHITE...WHITFIELD...WILKES...WILKINSON.
&&
$$
SHORT TERM...17
LONG TERM....TDP
AVIATION...17
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
141 PM EDT SUN MAY 19 2013
.UPDATE...
/ISSUED AT 741 AM EDT SUN MAY 19 2013/
UPDATED THE FORECAST TO ADD THE FLOOD WATCH.
&&
.PREV DISCUSSION... /ISSUED 357 AM EDT SUN MAY 19 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
500MB ANALYSIS SHOWS AN UPPER LOW ACROSS SOUTHERN KY WITH A
SHORTWAVE TROUGH EXTENDING INTO NORTHERN GA. THIS FEATURE HAS HELPED
DEVELOP AND SUSTAIN CONVECTION ACROSS NORTHERN PORTIONS OF THE CWFA
EARLY THIS MORNING. ABUNDANT MOISTURE AND LIGHT BOUNDARY LAYER WINDS
HAVE COMBINED TO PRODUCE SLOW MOVING HEAVY RAINERS. MPE PLACES AN
AXIS OF HEAVY RAIN FROM SOUTHEAST WALKER COUNTY INTO EASTERN DAWSON
COUNTY. THE MORE WIDESPREAD ACTIVITY IS SLOWLY PUSHING OFF TO THE
EAST...BUT CONVECTION CONTINUES TO DEVELOP BACK OFF TO THE WEST. DO
THINK THE PRIMARY THREAT FROM THUNDERSTORMS THIS MORNING WILL
CONTINUE TO BE LOCALLY HEAVY RAINFALL.
FORECAST CHALLENGE IN THIS WEATHER PATTERN IS WHERE CONVECTION WILL
DEVELOP. FOR THE NORTHERN AND CENTRAL CWFA...THE HRRR SEEMS TO HAVE
THE BEST HANDLE ON THE CURRENT CONVECTIVE TRENDS. THIS HAS BEEN THE
CASE FOR THE LAST SEVERAL DAYS. HAVE MODELED POPS AROUND THE HRRR
OUTPUT FOR MUCH OF THE FIRST PERIOD. DO EXPECT ADDITIONAL STORMS TO
KEEP FIRING ACROSS NW GA THIS MORNING AND SPREADING SOUTHEAST. THE
SYNOPTIC MODELS ARE STILL HINTING AT A MCS TYPE FEATURE DEVELOPING
ACROSS THE CENTRAL CWFA AND PUSHING SE TODAY. THE HRRR ACTUALLY IS
HINTING AT THIS ALSO. NOT VERY CONFIDENT THIS WILL
HAPPEN...ESPECIALLY WITH ALL OF THE CLOUD DEBRIS AROUND. MORE
SCATTERED ACTIVITY COULD DEVELOP ALONG THE SOUTHERN TIER OF
ZONES...WHERE THEY HAVE THE BEST CHANCE OF SEEING THE MOST HEATING.
IF AN MCS FEATURE DOES DEVELOP...ANY SEVERE THUNDERSTORMS THAT
DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE WET MICROBURSTS. FLASH
FLOODING WILL ALSO BE A HAZARD...ESPECIALLY WHERE STORMS REPEATEDLY
MOVE.
TOOK BLEND FOR TEMPS.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
PREICP SHOULD END FROM WEST TO EAST TONIGHT AS THE SHORTWAVE TROUGH
SETS UP ALONG THE EASTERN SEABOARD. HAVE ONLY TWEAKED POPS DURING
THIS PERIOD.
FOR THE FIRST PART OF THE WEEK...THE 500MB TROUGH/SHEAR AXIS REMAINS
ACROSS THE SE COAST. THIS FEATURE WILL HELP FOCUS SCT DIURNAL
CONVECTION EACH DAY. PREVIOUS RUNS PUSHED THE FEATURE OFF THE COAST
ON TUESDAY...BUT IT SHOULD REMAIN IN PLACE UNTIL EARLY WEDNESDAY.
FOR THE LATTER PART OF THE WEEK...A COLD FRONT IS EXPECTED TO MOVE
INTO THE SOUTHEAST STATES. MODEL RUN TO RUN CONSISTENCY FOR THIS
FEATURE HAS BEEN LOW FOR THE PAST FEW DAYS. THE ECMWF NOW HAS THE
BOUNDARY APPROACHING NORTHERN GA ON FRIDAY...AND MOVING THROUGH THE
CWFA DURING THE DAY. THE GFS HAS CONTINUES TO BRING THE BOUNDARY
SOUTHWARD. NEITHER MODEL IS PRODUCING MUCH PRECIP WITH THIS FEATURE
FOR NOW...SO WILL LEAVE POPS IN THE SCT RANGE.
HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
MAIN CHANGES TO THE EXTENDED WERE TO UP POPS SLIGHTLY IN THE EAST
FOR WEDNESDAY. MAINLY PERSISTENCE FOR THE LATTER HALF OF WEEK.
&&
.AVIATION...
18Z UPDATE...
REDEVELOPMENT OF CONVECTION OVER NORTHEAST AND EAST CENTRAL ALABAMA
WILL KEEP THE RISK OF THUNDER THROUGH THE AFTERNOON. CONVECTION WILL
DIMINISH THIS EVENING WITH STRATUS/STRATO CU FORMING LATE TONIGHT
WITH CIGS DROPPING TO MVFR/IFR. ALL AREAS SHOULD RISE TO VFR BY 18Z
MONDAY. WINDS WILL BE SOUTH SOUTHWEST LESS THAN 10 KTS...THEN LIGHT
AND VARIABLE TONIGHT...THEN SOUTH SOUTHWEST MONDAY.
//ATL CONFIDENCE...12Z UPDATE...
LOW CONFIDENCE ON CIGS AND TIMING OF SHRA/TSRA.
MEDIUM CONFIDENCE REMAINDER OF ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 79 64 85 66 / 90 40 30 20
ATLANTA 80 66 86 66 / 100 40 20 10
BLAIRSVILLE 73 59 83 60 / 80 30 30 20
CARTERSVILLE 80 65 88 65 / 100 40 20 20
COLUMBUS 86 67 90 67 / 70 50 20 10
GAINESVILLE 77 63 85 65 / 90 40 30 20
MACON 85 66 88 66 / 80 40 30 10
ROME 81 65 89 65 / 100 40 20 20
PEACHTREE CITY 81 64 87 64 / 100 40 20 10
VIDALIA 84 67 83 66 / 90 40 40 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH THIS EVENING FOR THE FOLLOWING ZONES:
BALDWIN...BANKS...BARROW...BARTOW...BIBB...BUTTS...CARROLL...
CATOOSA...CHATTOOGA...CHEROKEE...CLARKE...CLAYTON...COBB...
COWETA...CRAWFORD...DADE...DAWSON...DEKALB...DOUGLAS...FANNIN...
FAYETTE...FLOYD...FORSYTH...GILMER...GLASCOCK...GORDON...
GREENE...GWINNETT...HALL...HANCOCK...HARALSON...HEARD...HENRY...
JACKSON...JASPER...JEFFERSON...JONES...LAMAR...LUMPKIN...
MADISON...MERIWETHER...MONROE...MORGAN...MURRAY...NEWTON...NORTH
FULTON...OCONEE...OGLETHORPE...PAULDING...PICKENS...PIKE...
POLK...PUTNAM...ROCKDALE...SOUTH FULTON...SPALDING...
TALIAFERRO...TOWNS...TROUP...UNION...UPSON...WALKER...WALTON...
WARREN...WASHINGTON...WHITE...WHITFIELD...WILKES...WILKINSON.
&&
$$
SHORT TERM...NLISTEMAA
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1057 AM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL DISSIPATE OVER THE AREA THROUGH TUESDAY.
OTHERWISE ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT WEATHER FEATURE
THROUGH FRIDAY WHEN A COLD FRONT DROPS INTO THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE THIS MORNING...LINGERING SHOWER ACTIVITY FROM THE OVERNIGHT
PERIOD HAS WRAPPED UP AND MUCH OF THE FORECAST AREA IS CURRENTLY
PRECIP FREE. THIS WON/T LAST LONG AS VISIBLE SATELLITE SHOWS CU
ALREADY FORMING UNDER THE THIN HIGH CLOUDS ACROSS SOUTHEAST GA AND
THE FIRST HINTS OF DIURNAL SHOWERS ARE SHOWING UP ON RADAR
IMAGERY. FOR TODAY...THERE ARE A LOT OF SIMILARITIES TO YESTERDAY.
THE BAGGY MID-LEVEL TROUGH PERSISTS TO THE NORTHWEST...AN ONGOING
AND LEFTOVER CONVECTIVE COMPLEX IS UPSTREAM ACROSS NORTH/CENTRAL
GA...AND MID/HIGH LEVEL CLOUDS ASSOCIATED WITH IT ARE SPREADING
ACROSS INLAND COUNTIES. SOME DIFFERENCES TO YESTERDAY INCLUDE
WARMER 500 MB TEMPS...BUT ALSO COOLER 850 MB TEMPS WHICH WILL
RESULT IN LITTLE TO NO CAP THROUGH THE DAY. IN SUMMARY...WE ARE
LEFT WITH AN INCREASINGLY MOIST AIRMASS WITH NO
CAP...WEAK/MODERATE INSTABILITY. CONVECTIVE INITIATION AND
COVERAGE WILL LARGELY BE DETERMINED BY MESOSCALE BOUNDARY
INTERACTIONS FROM OUTFLOW ORIGINATING FROM THE UPSTREAM
CONVECTION...AND THE INLAND PENETRATING SEABREEZE. RECENT RUNS OF
HI-RES MODELS SHOW A CONVECTION DISTRIBUTION SIMILAR TO
YESTERDAY...FAVORING AREAS ALONG AND WEST OF I-95. FOR POPS I HAVE
MORE CLOSELY FOLLOWED THE HRRR WHICH HAD THE BEST REPRESENTATION
OF THE MORNING SHOWERS. I HAVE INCREASED POPS TO LIKELY FOR THE
REGION ALONG AND WEST OF I-95. REGARDING THE SEVERE THREAT...NO
PARAMETERS REALLY JUMP OFF THE PAGE AND THE BEST CHANCE FOR AN
ISOLATED SEVERE STORM WILL BE WHERE THE STRONGEST BOUNDARY
INTERACTIONS OCCUR. IF A STORM WERE TO BECOME SEVERE IT WILL
LIKELY ONLY BE SO FOR A VERY SHORT PERIOD OF TIME DUE TO THE PULSE
NATURE OF THE CONVECTION. OF SLIGHTLY MORE CONCERN IS THE HEAVY
RAIN POTENTIAL. PWATS WILL BE QUITE HIGH...MAXING OUT AROUND 2
STANDARD DEVIATIONS ABOVE NORMAL...AND RAINFALL PRODUCTION WILL BE
QUITE EFFICIENT. SINCE THE AREAS WHERE POPS ARE THE HIGHEST
RECEIVED THE MOST RAIN YESTERDAY...LOCALLY EXCESSIVE RAINFALL
COULD RESULT IN MINOR FLOODING OF LOW LYING AND POOR DRAINAGE
AREAS. TEMPS WILL REACH THE LOW TO MID 80S...WITH SOME POTENTIAL
TO BE HIGHER IN AREAS THAT SEE MORE BREAKS IN CLOUD COVER THIS
AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
THE MID LEVEL DISTURBANCE TO THE N WILL DRIFT TOWARD THE FOOTHILLS
OF VIRGINIA/NORTH CAROLINA BY LATE TONIGHT. CONVECTIVE RAINS WILL
LINGER THROUGH THE EVENING OVER INLAND AREAS WITH A GRADUAL TREND
TOWARD DECREASING COVERAGE/INTENSITY OF CONVECTION AFTER SUNSET...
ESPECIALLY OVER INLAND SE GEORGIA. IN SOUTH CAROLINA ADJACENT TO THE
MIDLANDS AND PEE DEE REGIONS...WE MAY SEE CONVECTIVE RAINS HANG
ON INTO THE NIGHT. LATE NIGHT SHOWERS/ISOLATED TSTMS ALSO POSSIBLE
ALONG COASTAL SOUTH CAROLINA WHERE SPEED/MOISTURE CONVERGENCE
INCREASE AFTER MIDNIGHT.
A JUICY AIRMASS WILL RESIDE ACROSS THE FORECAST AREA MONDAY INTO
TUESDAY WITH PW VALUES HOVERING AROUND 1.8 INCHES. UPPER SHORTWAVE
ENERGY WILL BE OVER THE AREA ON MONDAY BEFORE DISSIPATING MONDAY
NIGHT AND TUESDAY AS WEAK UPPER RIDGING OCCURS. THE BEST COVERAGE OF
SHOWERS AND TSTMS IS EXPECTED MONDAY WITH DIMINISHING COVERAGE EACH
DAY THEREAFTER. THE INCREASING UPPER HEIGHTS WILL ALSO RESULT IN A
GRADUAL WARMING TREND WITH INLAND HIGHS CLIMBING BACK TO NEAR 90 BY
WEDNESDAY. SOME LOCALLY HEAVY RAINFALL WILL BE POSSIBLE ON MONDAY
GIVEN DECENT INSTABILITY COMBINED WITH THE UPPER FORCING...
UNSEASONABLY HIGH PRECIPITABLE WATER VALUES AND STEERING FLOW LESS
THAN 10 KT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
AT KSAV...CONSENSUS OF 00Z AND 06Z HIGH RESOLUTION GUIDANCE
SUGGESTS THE TERMINAL WILL BE IMPACTED BY AT LEAST TSTMS IN THE
VICINITY OF THE I-95 CORRIDOR THIS AFTERNOON. WE HAVE INTRODUCED
TEMPO TSRA FROM 18Z-22Z BUT SUSPECT TIMING/COVERAGE WILL NEED
ADJUSTMENTS AS RADAR TRENDS BECOME BETTER DEFINED. THERE IS A RISK
FOR ADDITIONAL CONVECTIVE RAINS TONIGHT BUT CONFIDENCE IS GREATER
FOR AREAS TO THE NORTH AND WE HAVE LEANED TOWARD A VFR FORECAST
TONIGHT.
AT KCHS...THERE HAS BEEN VCSH THIS MORNING BUT THE BRUNT OF THE
OVERNIGHT CONVECTIVE RAINS DEVELOPED SLIGHTLY UP THE COAST FROM
THE TERMINAL. WE THINK SHOWERS OR EVEN AN ISOLATED TSTM COULD
DEVELOP THIS MORNING BUT CONFIDENCE IS LOW FOR ANY SIGNIFICANT
COVERAGE...SO MORNING VCSH FOR NOW. MODELS FAIRLY EMPHATIC KEEPING
WIDESPREAD AFTERNOON CONVECTION MAINLY W AND SW OF THE TERMINAL.
TONIGHT COULD BE A DIFFERENT STORY AS MOISTURE CONVERGENCE AND AN
UPPER DISTURBANCE EXPECTED TO ADDITIONAL SHOWERS AND A FEW TSTMS.
A BIT EARLY FOR ANYTHING PREVAILING BUT WE HAVE A VCSH FOR AFTER
MIDNIGHT.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS IN
CEILINGS AND VISIBILITIES ASSOCIATED WITH SCATTERED SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES WILL BE IN
THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY.
&&
.MARINE...
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS AVERAGING LESS THAN 15 KNOTS THROUGH TONIGHT. SEAS THIS MORNING
MAINLY IN THE 2 FT RANGE BUT GRADUALLY EDGING INTO THE 2 TO 4 FEET
RANGE THROUGH TONIGHT. THE 4 FT SEAS SHOULD BE RELEGATED TO OUTER
GEORGIA WATERS SEAWARD FROM GRAYS REEF.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH NEXT WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY NEXT WEEK. SEAS WILL
AVERAGE 2 TO 4 FEET MUCH OF THE TIME...ALTHOUGH SEAS AS HIGH AS
5-6 FT COULD BEGIN TO IMPINGE UPON WATERS BEYOND 20 NM BY MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
741 AM EDT SUN MAY 19 2013
.UPDATE...
UPDATED THE FORECAST TO ADD THE FLOOD WATCH.
&&
.PREV DISCUSSION... /ISSUED 357 AM EDT SUN MAY 19 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
500MB ANALYSIS SHOWS AN UPPER LOW ACROSS SOUTHERN KY WITH A
SHORTWAVE TROUGH EXTENDING INTO NORTHERN GA. THIS FEATURE HAS HELPED
DEVELOP AND SUSTAIN CONVECTION ACROSS NORTHERN PORTIONS OF THE CWFA
EARLY THIS MORNING. ABUNDANT MOISTURE AND LIGHT BOUNDARY LAYER WINDS
HAVE COMBINED TO PRODUCE SLOW MOVING HEAVY RAINERS. MPE PLACES AN
AXIS OF HEAVY RAIN FROM SOUTHEAST WALKER COUNTY INTO EASTERN DAWSON
COUNTY. THE MORE WIDESPREAD ACTIVITY IS SLOWLY PUSHING OFF TO THE
EAST...BUT CONVECTION CONTINUES TO DEVELOP BACK OFF TO THE WEST. DO
THINK THE PRIMARY THREAT FROM THUNDERSTORMS THIS MORNING WILL
CONTINUE TO BE LOCALLY HEAVY RAINFALL.
FORECAST CHALLENGE IN THIS WEATHER PATTERN IS WHERE CONVECTION WILL
DEVELOP. FOR THE NORTHERN AND CENTRAL CWFA...THE HRRR SEEMS TO HAVE
THE BEST HANDLE ON THE CURRENT CONVECTIVE TRENDS. THIS HAS BEEN THE
CASE FOR THE LAST SEVERAL DAYS. HAVE MODELED POPS AROUND THE HRRR
OUTPUT FOR MUCH OF THE FIRST PERIOD. DO EXPECT ADDITIONAL STORMS TO
KEEP FIRING ACROSS NW GA THIS MORNING AND SPREADING SOUTHEAST. THE
SYNOPTIC MODELS ARE STILL HINTING AT A MCS TYPE FEATURE DEVELOPING
ACROSS THE CENTRAL CWFA AND PUSHING SE TODAY. THE HRRR ACTUALLY IS
HINTING AT THIS ALSO. NOT VERY CONFIDENT THIS WILL
HAPPEN...ESPECIALLY WITH ALL OF THE CLOUD DEBRIS AROUND. MORE
SCATTERED ACTIVITY COULD DEVELOP ALONG THE SOUTHERN TIER OF
ZONES...WHERE THEY HAVE THE BEST CHANCE OF SEEING THE MOST HEATING.
IF AN MCS FEATURE DOES DEVELOP...ANY SEVERE THUNDERSTORMS THAT
DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE WET MICROBURSTS. FLASH
FLOODING WILL ALSO BE A HAZARD...ESPECIALLY WHERE STORMS REPEATEDLY
MOVE.
TOOK BLEND FOR TEMPS.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
PREICP SHOULD END FROM WEST TO EAST TONIGHT AS THE SHORTWAVE TROUGH
SETS UP ALONG THE EASTERN SEABOARD. HAVE ONLY TWEAKED POPS DURING
THIS PERIOD.
FOR THE FIRST PART OF THE WEEK...THE 500MB TROUGH/SHEAR AXIS REMAINS
ACROSS THE SE COAST. THIS FEATURE WILL HELP FOCUS SCT DIURNAL
CONVECTION EACH DAY. PREVIOUS RUNS PUSHED THE FEATURE OFF THE COAST
ON TUESDAY...BUT IT SHOULD REMAIN IN PLACE UNTIL EARLY WEDNESDAY.
FOR THE LATTER PART OF THE WEEK...A COLD FRONT IS EXPECTED TO MOVE
INTO THE SOUTHEAST STATES. MODEL RUN TO RUN CONSISTENCY FOR THIS
FEATURE HAS BEEN LOW FOR THE PAST FEW DAYS. THE ECMWF NOW HAS THE
BOUNDARY APPROACHING NORTHERN GA ON FRIDAY...AND MOVING THROUGH THE
CWFA DURING THE DAY. THE GFS HAS CONTINUES TO BRING THE BOUNDARY
SOUTHWARD. NEITHER MODEL IS PRODUCING MUCH PRECIP WITH THIS FEATURE
FOR NOW...SO WILL LEAVE POPS IN THE SCT RANGE.
HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
MAIN CHANGES TO THE EXTENDED WERE TO UP POPS SLIGHTLY IN THE EAST
FOR WEDNESDAY. MAINLY PERSISTENCE FOR THE LATTER HALF OF WEEK.
.AVIATION...
12Z UPDATE...
CURRENT PATTERN MAKES IT DIFFICULT TO FORECAST THE TIMING OF
CONVECTION. FOLLOWED THE 06Z RUN OF THE HRRR FAIRLY CLOSELY FOR
CONVECTIVE ELEMENTS...OVER THE LAST FEW DAYS...IT HAS BEEN THE
BEST MODEL. WINDS HAVE TEMPORARILY SWITCHED TO THE NE IN
THUNDERSTORM OUTFLOW.
//ATL CONFIDENCE...06Z UPDATE...
LOW CONFIDENCE ON CIGS AND TIMING OF SHRA/TSRA. MEDIUM CONFIDENCE
REMAINDER OF ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 79 64 85 66 / 90 40 30 20
ATLANTA 80 66 86 66 / 100 40 20 10
BLAIRSVILLE 73 59 83 60 / 80 30 30 20
CARTERSVILLE 80 65 88 65 / 100 40 20 20
COLUMBUS 86 67 90 67 / 70 50 20 10
GAINESVILLE 77 63 85 65 / 90 40 30 20
MACON 85 66 88 66 / 80 40 30 10
ROME 81 65 89 65 / 100 40 20 20
PEACHTREE CITY 81 64 87 64 / 100 40 20 10
VIDALIA 84 67 83 66 / 90 40 40 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH THIS EVENING FOR THE FOLLOWING ZONES:
BALDWIN...BANKS...BARROW...BARTOW...BIBB...BUTTS...CARROLL...
CATOOSA...CHATTOOGA...CHEROKEE...CLARKE...CLAYTON...COBB...
COWETA...CRAWFORD...DADE...DAWSON...DEKALB...DOUGLAS...FANNIN...
FAYETTE...FLOYD...FORSYTH...GILMER...GLASCOCK...GORDON...
GREENE...GWINNETT...HALL...HANCOCK...HARALSON...HEARD...HENRY...
JACKSON...JASPER...JEFFERSON...JONES...LAMAR...LUMPKIN...
MADISON...MERIWETHER...MONROE...MORGAN...MURRAY...NEWTON...NORTH
FULTON...OCONEE...OGLETHORPE...PAULDING...PICKENS...PIKE...
POLK...PUTNAM...ROCKDALE...SOUTH FULTON...SPALDING...
TALIAFERRO...TOWNS...TROUP...UNION...UPSON...WALKER...WALTON...
WARREN...WASHINGTON...WHITE...WHITFIELD...WILKES...WILKINSON.
&&
$$
SHORT TERM...NLISTEMAA
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
357 AM EDT SUN MAY 19 2013
.SHORT TERM /TODAY THROUGH MONDAY/...
500MB ANALYSIS SHOWS AN UPPER LOW ACROSS SOUTHERN KY WITH A
SHORTWAVE TROUGH EXTENDING INTO NORTHERN GA. THIS FEATURE HAS HELPED
DEVELOP AND SUSTAIN CONVECTION ACROSS NORTHERN PORTIONS OF THE CWFA
EARLY THIS MORNING. ABUNDANT MOISTURE AND LIGHT BOUNDARY LAYER WINDS
HAVE COMBINED TO PRODUCE SLOW MOVING HEAVY RAINERS. MPE PLACES AN
AXIS OF HEAVY RAIN FROM SOUTHEAST WALKER COUNTY INTO EASTERN DAWSON
COUNTY. THE MORE WIDESPREAD ACTIVITY IS SLOWLY PUSHING OFF TO THE
EAST...BUT CONVECTION CONTINUES TO DEVELOP BACK OFF TO THE WEST. DO
THINK THE PRIMARY THREAT FROM THUNDERSTORMS THIS MORNING WILL
CONTINUE TO BE LOCALLY HEAVY RAINFALL.
FORECAST CHALLENGE IN THIS WEATHER PATTERN IS WHERE CONVECTION WILL
DEVELOP. FOR THE NORTHERN AND CENTRAL CWFA...THE HRRR SEEMS TO HAVE
THE BEST HANDLE ON THE CURRENT CONVECTIVE TRENDS. THIS HAS BEEN THE
CASE FOR THE LAST SEVERAL DAYS. HAVE MODELED POPS AROUND THE HRRR
OUTPUT FOR MUCH OF THE FIRST PERIOD. DO EXPECT ADDITIONAL STORMS TO
KEEP FIRING ACROSS NW GA THIS MORNING AND SPREADING SOUTHEAST. THE
SYNOPTIC MODELS ARE STILL HINTING AT A MCS TYPE FEATURE DEVELOPING
ACROSS THE CENTRAL CWFA AND PUSHING SE TODAY. THE HRRR ACTUALLY IS
HINTING AT THIS ALSO. NOT VERY CONFIDENT THIS WILL
HAPPEN...ESPECIALLY WITH ALL OF THE CLOUD DEBRIS AROUND. MORE
SCATTERED ACTIVITY COULD DEVELOP ALONG THE SOUTHERN TIER OF
ZONES...WHERE THEY HAVE THE BEST CHANCE OF SEEING THE MOST HEATING.
IF AN MCS FEATURE DOES DEVELOP...ANY SEVERE THUNDERSTORMS THAT
DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE WET MICROBURSTS. FLASH
FLOODING WILL ALSO BE A HAZARD...ESPECIALLY WHERE STORMS REPEATEDLY
MOVE.
TOOK BLEND FOR TEMPS.
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
PREICP SHOULD END FROM WEST TO EAST TONIGHT AS THE SHORTWAVE TROUGH
SETS UP ALONG THE EASTERN SEABOARD. HAVE ONLY TWEAKED POPS DURING
THIS PERIOD.
FOR THE FIRST PART OF THE WEEK...THE 500MB TROUGH/SHEAR AXIS REMAINS
ACROSS THE SE COAST. THIS FEATURE WILL HELP FOCUS SCT DIURNAL
CONVECTION EACH DAY. PREVIOUS RUNS PUSHED THE FEATURE OFF THE COAST
ON TUESDAY...BUT IT SHOULD REMAIN IN PLACE UNTIL EARLY WEDNESDAY.
FOR THE LATTER PART OF THE WEEK...A COLD FRONT IS EXPECTED TO MOVE
INTO THE SOUTHEAST STATES. MODEL RUN TO RUN CONSISTENCY FOR THIS
FEATURE HAS BEEN LOW FOR THE PAST FEW DAYS. THE ECMWF NOW HAS THE
BOUNDARY APPROACHING NORTHERN GA ON FRIDAY...AND MOVING THROUGH THE
CWFA DURING THE DAY. THE GFS HAS CONTINUES TO BRING THE BOUNDARY
SOUTHWARD. NEITHER MODEL IS PRODUCING MUCH PRECIP WITH THIS FEATURE
FOR NOW...SO WILL LEAVE POPS IN THE SCT RANGE.
HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
MAIN CHANGES TO THE EXTENDED WERE TO UP POPS SLIGHTLY IN THE EAST
FOR WEDNESDAY. MAINLY PERSISTENCE FOR THE LATTER HALF OF WEEK.
&&
AVIATION...
06Z UPDATE...
CURRENT PATTERN MAKES IT DIFFICULT TO FORECAST THE TIMING OF
CONVECTION. FOLLOWED THE LATEST RUN OF THE HRRR FAIRLY CLOSELY FOR
CONVECTIVE ELEMENTS...OVER THE LAST FEW DAYS...IT HAS BEEN THE
BEST MODEL. CIGS AND WINDS WILL ALSO BE A CHALLENGE. MODELS DO
HAVE CIG VALUES DIPPING TO IFR AND OBS REFLECT THIS...ALSO AREAS
OF FOG WILL BE PRESENT BUT ONLY HAVE 5-6SM PREV. MORNING
CONVECTION MAY LIMIT AFTERNOON DEVELOPMENT.
//ATL CONFIDENCE...06Z UPDATE...
LOW CONFIDENCE ON CIGS AND TIMING OF SHRA/TSRA. MEDIUM CONFIDENCE
REMAINDER OF ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 79 64 85 66 / 60 50 30 20
ATLANTA 80 66 86 66 / 60 30 20 10
BLAIRSVILLE 73 59 83 60 / 70 50 30 20
CARTERSVILLE 80 65 88 65 / 60 30 20 20
COLUMBUS 86 67 90 67 / 40 30 20 10
GAINESVILLE 77 63 85 65 / 70 50 30 20
MACON 85 66 88 66 / 50 30 30 10
ROME 81 65 89 65 / 60 30 20 20
PEACHTREE CITY 81 64 87 64 / 50 30 20 10
VIDALIA 84 67 83 66 / 50 50 40 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...NLISTEMAA
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
142 AM EDT SUN MAY 19 2013
.PREV DISCUSSION... /ISSUED 1009 PM EDT SAT MAY 18 2013/
UPDATE...
HI RES MODELS HAVE NOT BEEN HANDLING THE CONVECTION WELL AT ALL
THIS EVENING AND WERE OVERDOING IT THIS AFTERNOON. HRRR HAS
PROBABLY BEEN THE BEST BUT STILL NOT QUITE CATCHING TRENDS.
STARTING TO SEE MORE DEVELOPMENT OVER THE PAST HOUR...PARTICULARLY
ACROSS NORTHWEST GEORGIA. SHOULD SEE AN INCREASE IN COVERAGE BY
SUNRISE. STILL NOT CONFIDENT ON WHAT IS GOING TO HAPPEN TOMORROW
IN TERMS OF CONVECTION. A FEW MODELS ARE LIMITING ACTIVITY...WHILE
SOME ARE SHOWING A MORE ACTIVE AFTERNOON. MAIN CHANGE TO THE
FORECAST TONIGHT WAS TO DECREASE POPS INITIALLY BUT SHOW A TREND
OF INCREASING POPS LATE TONIGHT. TWEAKED TOMORROW AND TOMORROW
EVENING BY TRYING TO SHOW A TREND OF DECREASING POPS ACROSS THE
WESTERN PART OF THE CWA LATE IN THE DAY. GIVEN FORECAST
INSTABILITY...HAVE CONTINUED MENTION OF SLIGHT CHANCE OF THUNDER
OVERNIGHT TONIGHT.
11
PREV DISCUSSION...
SHORT TERM /TONIGHT THROUGH SUNDAY/...
/ISSUED 326 PM EDT SAT MAY 18 2013/
WEAK UPPER LOW OVER THE TENNESSEE VALLEY IS SLOWLY PULLING EAST.
WEAK DISTURBANCES ROTATING THROUGH THE FLOW OVER AL AND GA WAS
PRODUCING SCATTERED SHOWERS/TSTORMS. THE PRECIP SHOULD DIMINISH THIS
EVENING...BUT AS ANOTHER WEAK WAVE MOVES INTO SOUTHEAST TENNESSEE
LATE TONIGHT...EXPECT CONVECTION TO INCREASE ACROSS NORTH GA AND
SPREAD SOUTH AND EAST SUNDAY. MODELS ARE RATHER CONSERVATIVE WITH
THE POPS AND HAVE CONTINUED WITH LIKELY POPS FOR SUNDAY. AT THIS
TIME EXPECT A FEW STORMS TO BE STRONG AND AN ISOLATED SEVERE STORM
IS STILL NOT OUT OF THE QUESTION SUNDAY AFTERNOON...MAINLY ACROSS
WEST CENTRAL GA. THERE REMAINS PLENTY OF ISENTROPIC LIFT AND K-INDEX
VALUES ARE QUITE HIGH AND THEREFORE EXPECT SOME HEAVY RAIN IN SOME
OF THE STRONGER STORMS. WITH LITTLE SURFACE WIND TONIGHT AND PLENTY
OF SURFACE MOISTURE...EXPECT FOG/STRATUS TO DEVELOP ACROSS WEST
CENTRAL GEORGIA WHICH SHOULD SPREAD NORTH AND EAST LATE TONIGHT.
17
LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
NO CHANGES NEEDED TO THE PREVIOUS EXTENDED FORECAST RATIONALE.
16
HAVE ADJUSTED POPS UPWARD FOR SUNDAY NIGHT ACROSS THE CWFA.
MODELS ARE SHOWING SIGNS OF AN MCS DEVELOPING IN THE NW FLOW AND
AFFECTING THE CWFA. STRONG SURFACE INSTABILITY AND VERY STEEP
LAPSE RATES WILL HELP SUSTAIN CONVECTION AND CONTINUE THE
POSSIBILITY OF SEVERE STORMS AT LEAST THROUGH MIDNIGHT.
FOR MONDAY...A 500MB TROUGH/SHEAR AXIS SETS UP RIGHT ALONG THE SE
COAST. THIS FEATURE SHOULD SERVE TO FOCUS ANY CONVECTIVE ACTIVITY
FOR MONDAY AND MONDAY EVENING. DO THINK SHRA/TSRA WILL BE MORE
DIURNAL IN NATURE. KEPT THE TREND OF HIGHEST POPS IN THE EAST...WITH
ONLY ISOLATED ACTIVITY TO THE WEST.
WEAK SHEAR AXIS/500MB TROUGH MOVES OFF THE COAST ON TUESDAY WITH
RIDGING BUILDING ALOFT ACROSS THE CWFA. ANY CONVECTION SHOULD BE
ISOLATED IN NATURE...SURFACE INSTABILITY WILL BE PRESENT BUT NO
DISCERNIBLE SURFACE MECHANISM TO FOCUS PRECIP IS NOTED. PRECIP
SHOULD BE DIURNAL.
UNCERTAINTY BEGINS TO CREEP INTO THE FORECAST BY WEDNESDAY. EARLIER
MODEL RUNS PROGGED A COLD FRONT TO MOVE THROUGH THE CWFA DURING THE
LATTER HALF OF THE WEEK. THE ECMWF NOW KEEPS THE FRONT TO THE
NORTH...WHILE THE GFS DOES MOVE THE BOUNDARY THROUGH SLOWLY FRIDAY
THROUGH SATURDAY. HAVE OPTED TO GO PERSISTENCE FOR THIS PERIOD DUE
TO LOW CONFIDENCE.
NLISTEMAA
&&
.AVIATION...
06Z UPDATE...
CURRENT PATTERN MAKES IT DIFFICULT TO FORECAST THE TIMING OF
CONVECTION. FOLLOWED THE LATEST RUN OF THE HRRR FAIRLY CLOSELY FOR
CONVECTIVE ELEMENTS...OVER THE LAST FEW DAYS...IT HAS BEEN THE
BEST MODEL. CIGS AND WINDS WILL ALSO BE A CHALLENGE. MODELS DO
HAVE CIG VALUES DIPPING TO IFR AND OBS REFLECT THIS...ALSO AREAS
OF FOG WILL BE PRESENT BUT ONLY HAVE 5-6SM PREV. MORNING
CONVECTION MAY LIMIT AFTERNOON DEVELOPMENT.
//ATL CONFIDENCE...06Z UPDATE...
LOW CONFIDENCE ON CIGS AND TIMING OF SHRA/TSRA. MEDIUM CONFIDENCE
REMAINDER OF ELEMENTS.
NLISTEMAA
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 77 65 84 66 / 60 50 30 20
ATLANTA 81 66 86 66 / 60 30 20 10
BLAIRSVILLE 76 60 82 61 / 70 50 30 20
CARTERSVILLE 81 65 88 67 / 60 30 20 20
COLUMBUS 86 67 89 68 / 40 30 20 10
GAINESVILLE 77 63 84 65 / 70 50 30 20
MACON 83 66 87 66 / 50 30 30 10
ROME 82 65 89 67 / 60 30 20 20
PEACHTREE CITY 82 65 87 66 / 50 30 20 10
VIDALIA 86 68 84 65 / 50 50 40 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ATWELL
LONG TERM....ATWELL
AVIATION...ATWELL
AREA FORECAST DISCUSSION
NWS LINCOLN IL
843 PM CDT MON MAY 20 2013
.DISCUSSION...
ISSUED 845 PM CDT MON MAY 20 2013
UPDATED THE FORECAST TONIGHT TO EXPAND THE TORNADO WATCH UNTIL 1
AM FROM MCLEAN...DEWITT...MACON AND CHRISTIAN COUNTIES WEST.
INCREASED TO CATEGORICAL POPS OF 80-100% FROM I-55 WEST THROUGH 1
AM INCLUDING RISK OF TORNADOES...LARGE HAIL...DAMAGING WIND GUSTS...
HEAVY RAINS AND FREQUENT LIGHTNING. HAVE CHANCE OF SHOWERS AND
THUNDERSTORMS DEVELOPING OVER EASTERN IL LATE THIS EVENING AND
CONTINUE LIKELY CHANCES OF SHOWERS AND THUNDERSTORMS OVERNIGHT
WHERE STRONG TO SEVERE STORMS POSSIBLE AS WELL AFTER MIDNIGHT OVER
EASTERN IL.
996 MB LOW PRESSURE OVER NE SD WITH WARM FRONT OVER NORTHERN WI/MI
AND ITS COLD FRONT OVER SW MN...WESTERN IA INTO SE KS AND CENTRAL OK.
STRONG 556 DM 500 MB LOW WAS ALSO OVER NE SD. SCATTERED TO
NUMEROUS STRONG TO SEVERE THUNDERSTORMS WAS SE OF THIS LARGE LOW
PRESSURE SYSTEM FROM THE IL RIVER VALLEY THRU CENTRAL MO INTO SE
OK AND CENTRAL TX. CONVECTION WAS AS FAR EAST AS I-55 AND RACING
NE AT 40 TO 50 MPH. SHORT WAVE EJECTING NE FROM OK AND OZARKS OF
NW AR AND SW MO INTO CENTRAL IL DURING TONIGHT TO PRODUCE
WIDESPREAD CONVECTION ACROSS CENTRAL AND EVENTUALLY EASTERN IL BY
OVERNIGHT. MUCH OF IL REMAINS IN SLIGHT RISK OF SEVERE STORMS
TONIGHT THROUGH TUE WHILE MODERATE RISK OF SEVERE STORMS TONIGHT
OVER SOUTHERN MO. THERE IS 30% RISK OF LARGE HAIL AND DAMAGING
WIND GUSTS OVER CENTRAL IL TONIGHT ESPECIALLY FROM I-57 WEST AND
5-10% RISK OF TORNADOES WITH SUPERCELLS. SPC SAID MCS TO EVOLVE
INTO QLCS DURING THIS EVENING AND CONTINUE RISK OF SEVERE STORMS
INTO CENTRAL IL TONIGHT. INCREASE QPF TONIGHT OVER CENTRAL IL WITH
AVERAGE HALF TO 1 INCH AMOUNTS AND LOCALLY 1-2 INCH AMOUNTS WITH
STRONGER STORMS. LOWS IN THE MIDDLE TO UPPER 60S BY DAWN.
07
&&
.AVIATION...
ISSUED 1246 PM CDT MON MAY 20 2013
CLUSTER OF THUNDERSTORMS CURRENTLY CROSSING THE MISSISSIPPI RIVER
JUST SOUTH OF QUINCY WILL TRACK E/NE INTO THE AREA EARLY THIS
AFTERNOON. AIRMASS IS BEGINNING TO DESTABILIZE IN ADVANCE OF THIS
CONVECTION...SO CONFIDENCE IS GROWING THAT IT WILL HOLD TOGETHER
AND ARRIVE AT KSPI BETWEEN 19Z AND 21Z. ITS EVOLUTION BEYOND THAT
STILL REMAINS IN QUESTION...SO WILL ONLY CARRY VCTS AFTER 21Z AT
THE REMAINING TERMINALS. OUTSIDE OF ANY CONVECTION THAT DEVELOPS
THIS AFTERNOON...STRONG SOUTHERLY WINDS WILL GUST TO BETWEEN 25
AND 30KT. MODELS DISAGREE ABOUT THE TIMING/PLACEMENT OF ADDITIONAL
CONVECTION LATER TODAY AND TONIGHT...HOWEVER THE HRRR CONTINUES TO
FOCUS THE MOST WIDESPREAD STORMS DURING THE EVENING INTO THE
OVERNIGHT HOURS. WILL THEREFORE KEEP TEMPO GROUPS FOR THUNDER
BETWEEN 02Z AND 06Z AT KPIA AND BETWEEN 04Z AND 08Z FURTHER EAST
AT KCMI. AFTER THAT...MID-LEVEL DRYING IN THE WAKE OF THE
OVERNIGHT CONVECTION WILL LEAD TO A DRY TUESDAY MORNING.
BARNES
&&
.PREV DISCUSSION...
ISSUED 222 PM CDT MON MAY 20 2013
SEVERE WEATHER CHANCES CONTINUE TO BE THE MAIN FOCUS...WITH RAIN
CHANCES LINGERING THROUGH THURSDAY. A COOLING TREND WILL DEVELOP
MID WEEK WITH BELOW NORMAL TEMPS FOR LATE WEEK AND INTO THE
WEEKEND.
SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT.
THE ATMOSPHERE STARTED OUT THE AFTERNOON A BIT MORE STABLE THAN
MODEL GUIDANCE HAD INDICATED. MUCAPE VALUES ARE IN AROUND 500 J/KG
WITH SOME CONVECTIVE INHIBITION OF 150-200 J/KG. SFC DEWPOINTS AND TEMPS
ARE ON THE RISE AND INCREASING MID LEVEL JET WINDS TO THE
SOUTHWEST SHOULD STILL TO NOSE INTO CENTRAL ILLINOIS BY EVENING.
THE ONSET OF SEVERE STORMS MAY BE SLIGHTLY DELAYED DUE TO THE TIME
IT WILL TAKE FOR THE INGREDIENTS FOR STORMS TO DEVELOP. THE
EVOLUTION SHOULD BE FOR DISCREET SUPERCELLS FORMING IN MISSOURI
AND ADVANCING EAST ALONG THE AXIS OF INSTABILITY FROM SW TO NE.
THE DIRECTIONAL SHEAR IN THE PLAINS WILL EVOLVE TO MORE
UNIDIRECTIONAL SHEAR ACROSS CENTRAL IL. THAT WILL HELP THE
SUPERCELLS TO EVOLVE INTO MORE OF A LINEAR SETUP, WITH STRAIGHT-
LINE AND DOWNBURST WINDS MORE LIKELY. EMBEDDED SUPERCELLS WILL
STILL BE POSSIBLE DUE TO AMBIENT VORTICITY NEAR PRE-EXISTING
CONVECTIVE BOUNDARIES ALL OVER CENTRAL ILLINOIS.
THE EVENING HOURS LOOK TO BE OUR PRIMARY SEVERE WINDOW...WITH A
DOWNWARD TREND IN SEVERE AFTER MIDNIGHT AS THE STORMS HEAD INTO
OUR EASTERN COUNTIES. THE 4KM HRRR IS DEPICTING THE NW HALF OF OUR
AREA TO HAVE THE BEST CHANCES FOR STORMS...WITH LINEAR STORM
SEGMENTS DEVELOPING AFTER MIDNIGHT IN THE SOUTHEAST HALF...AND A
MORE ISOLATED SEVERE THREAT BUT STILL PRESENT.
THE SEVERE POTENTIAL ON TUESDAY WILL BE TIED TO THE ADVANCEMENT OF
A 500 MB SHORTWAVE AND RESULTANT SURFACE CYCLOGENESIS FROM THE
SOUTHERN PLAINS ACROSS CENTRAL IL. THE PRIMARY FORCING FOR STORMS
LOOKS TO HOLD OFF UNTIL TUESDAY EVENING...WHEN THE WAVE WILL MOVES
INTO WESTERN IL. STORMS ARE EXPECTED TO ERUPT ACROSS EASTERN MO
AND SW IL IN THE EVENING AND PROGRESS TO THE E-NE OVERNIGHT. WE
SEVERE POTENTIAL SHOULD BE HIGHER SOUTHEAST OF I-55...BASED ON THE
TRACK OF THE SURFACE LOW AND LOCATION OF THE 850 MB LLJ.
STORMS SHOULD BE PRIMARY EAST OF OUR AREA BY SUNRISE
WEDNESDAY...BUT ADDITIONAL SHOWERS AND A FEW STORMS WILL BE
POSSIBLE AS COLD AIR ADVANCES INTO IL. VARIOUS SHORTWAVES WILL BE
ROTATING ACROSS ILLINOIS AS THE UPPER TROUGH AXIS MOVES INTO
WESTERN IL.
LONG TERM...THURSDAY THROUGH MONDAY.
ON THURSDAY...THE SLOW MOVEMENT OF THE UPPER LEVEL AND SURFACE
LOWS FROM THE NORTHERN PLAINS ACROSS THE GREAT LAKES WILL CAUSE
SHOWERS TO LINGER ACROSS CENTRAL IL. THE AXIS OF THE ELEVATED COLD
POOL ALOFT WILL PASS ACROSS IL AROUND MID-DAY THURSDAY. LAPSE
RATES APPEAR FAVORABLE FOR SOME INSTABILITY SHOWERS TO DEVELOP IN
THE HEAT OF THE DAY...WITH A LITTLE HELP FROM CHANNELED VORTICITY
IN THE LEE SIDE OF THE UPPER TROUGH.
CLEARING SKIES THURSDAY NIGHT WILL ALLOW LOWS TO DIP INTO THE
UPPER 40S NORTH OF A LINE FROM RUSHVILLE TO LINCOLN TO CHAMPAIGN.
DESPITE SUNSHINE ON FRIDAY...HIGH TEMPS WILL STRUGGLE TO REACH
AROUND 70 IN MOST OF THE AREA.
THE 00Z/20 ECMWF HAD A WET HOLIDAY WEEKEND FORECAST...WITH A DRY
FORECAST FROM THE 00Z/GFS. THEY APPEAR TO HAVE FLIP-FLOPPED THE
FORECAST WITH THE 12Z VERSIONS. THE 12Z GFS NOW SHOWING RAIN
CHANCES LATE SATURDAY THROUGH MEMORIAL DAY. THE ECMWF STILL HAS
SOME RAIN LATE FRI NIGHT INTO SATURDAY...BUT DRY CONDITIONS FOR
SUNDAY AND MEMORIAL DAY. THE ALLBLEND HAS BASICALLY KEPT SOME
MENTION OF RAIN DUE TO THE PRESENT SIGNAL FROM AT LEAST ONE MODEL
EACH DAY OF THE WEEKEND. THE MAIN THEME REMAINS THAT A WAVE OF
ENERGY IS FORECAST TO EXIT THE PLAINS EARLY IN THE WEEKEND BUT
WHERE THE FRONT STALLS OUT FOR LINGERING RAIN REMAINS TO BE SEEN.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
900 PM EDT MON MAY 20 2013
.AVIATION/UPDATE...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 857 PM EDT MON MAY 20 2013
DIFFICULT FORECAST WITH RESPECT TO CONVECTIVE PROBABILITIES THROUGH
THE FORECAST PERIOD AND DISMAL EARLY FAILURE. AMID A STRONGLY
DIVERGENT BOUNDARY LAYER AXIS PER VIS SAT IMAGERY LYING ACROSS
NERN IL/NWRN IN PAST FEW HOURS...HAS PROVEN TO BE STRONGLY
DETRIMENTAL. THIS DESPITE MODERATE SURFACE BASED INSTABILITY POOL
SITUATED ACROSS NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN THIS
EVENING. A WELL SCOURED/DEEPLY MIXED ENVIRONMENT EXISTS ACROSS
NORTHERN/CENTRAL ILLINOIS WITH PUTRID MID/UPR 50S DPS THIS
EVENING...REMOVES ANY IMMEDIATE CONCERN FOR INITIATION NEXT FEW
HOURS. THIS IMMEDIATE UPSTREAM ENVIRON WAS WITHIN WAKE OF EARLY
AFTERNOON SHORTWAVE...THAT INITIATED STRONG/SEVERE CONVECTION
MIDDAY ACROSS YOOP/NORTHERN LOWER MICHIGAN. EASTERN FRINGE OF DRY
SLOTTED ENVIRONMENT WITH 7.5-8.25 C/KM MID LEVEL LAPSE RATES TO
LIKELY KEEP UPDRAFTS IN CHECK/ISOLATED REMAINDER OF THE EVENING.
WILL MAINTAIN THAT ANY SIG CHANCE FOR CONVECTION TO BE ASSOCIATED
WITH WELL UPSTREAM CONVECTION PRESENTLY ACROSS EAST CENTRAL
MO...WITH SEVERAL HOUR WAIT UNTIL A MORE VIGORED UPSTREAM 925-8H
WIND FIELD WITH PRESENT FOCUS INTO THE OZARKS/NORTHERN ARKANSAS
SHIFTS NORTHEASTWARD OVERNIGHT INTO SRN/CENTRAL ILLINOIS WHILE
JETLET VEERS/RAMPS TO 45-55KTS...FINALLY NOSING INTO KLAF VCNTY
AROUND 09-12 UTC PER RAP/ARW...AND A SIGNIFICANTLY POOR/LAGGARD
HRRR3KM THAT RECENTLY CAME IN LINE TO REALITY. SUFFICIENT
PREPARATORY CONDITIONING/RECOVERY OF ENVIRONMENT VIA MOISTURE
FLUX CONVERGENCE SFC-900MB ALONG/NORTH OF STRONG ISODROSOTHERMAL
GRADIENT WITH UPPER 60S/NEAR 70 DPS SOURCE TAPPED WITH
TIME....PUSHING NORTH OF I70 TO MAINTAIN MUCAPE POOL OF 1200-2000
J/KG ACROSS FORECAST AREA. THIS SHOULD ALLOW DECENT MAINTENANCE OF
CONVECTIVE COMPLEX WITH ACROSS MISSOURI TO REACH NORTHERN INDIANA
WELL AFTER MIDNIGHT INTO KSBN AND NEAR DAYBREAK AT KFWA.
DISFAVORED TIMING/PARCEL ASCENT BECOMING LESS SURFACE BASED WITH
TIME AND MODEST DEEP LAYER SHEAR TO LARGELY PRECLUDE SEVERE
POTENTIAL...THOUGH HAVE CONTD TO ACK THAT STRONGEST CELLS MAY
APPROACH LOW END SEVERE LIMITS IN HWO.
&&
.SYNOPSIS...
ISSUED AT 532 PM EDT MON MAY 20 2013
SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE TO INCREASE TONIGHT
THROUGH WEDNESDAY...WITH A FEW SHOWERS POSSIBLY LINGERING INTO
THURSDAY. THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS
EVENING THROUGH TUESDAY NIGHT. DRIER AND COOLER WEATHER IS
ANTICIPATED LATE THIS WEEK INTO NEXT WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
REMNANT GRAVITY WAVE FROM OVERNIGHT CONVECTION AND
ASSOCIATED WITH A ~10F DEGREE DEWPOINT DROP IN ITS WAKE HAS WASHED
OUT AS IT MOVED INTO OUR FORECAST AREA. THIS HAS KEPT MODERATELY
UNSTABLE AIRMASS ACROSS THE EASTERN TWO-THIRDS OF OUR FORECAST AREA.
ADDED SLIGHT CHANCE POPS FOR THE EAST THIS EVENING AS CONVECTION
COULD FIRE ALONG OR IN FRONT OF THIS BOUNDARY WHERE THE AIRMASS IS
CHARACTERIZED BY SBCAPE VALUES IN EXCESS OF 3000 J/KG. THE GREATEST
LIMITING FACTOR IS THE LACK OF SIGNIFICANT FORCING...ALTHOUGH
CONVECTION ACROSS MICHIGAN AND ADDITIONAL CONVECTION FIRING ALONG
THE BOUNDARY ACROSS EASTERN ILLINOIS AT 1830Z INDICATES THIS
BOUNDARY MAY PROVIDE JUST ENOUGH FORCED ASCENT FOR ISOLATED STORM
DEVELOPMENT.
STILL SOME UNCERTAINTY REGARDING CONVECTIVE EVOLUTION AND IMPACTS
ACROSS OUR AREA TONIGHT. DECAYING STORM CLUSTER ACROSS WESTERN
ILLINOIS SHOULD CONTINUE ITS WEAKENING TREND AS IT MOVES INTO A
MOISTURE VOID AREA ACROSS ILLINOIS WITH SURFACE DEWPOINTS IN THE
UPPER 50S. WITH THAT BEING SAID...SOME SHORT TERM MODEL GUIDANCE IS
INDICATING A QUICK RECOVERY OF THE MOISTURE PROFILE IN THAT AREA AS
850 MOISTURE TRANSPORT INCREASES THIS AFTERNOON. IF THE AIRMASS
AHEAD OF THESE STORMS CAN DESTABILIZE OVER THE NEXT FEW HOURS...AS
THE HRRR SUGGESTS...UPSCALE GROWTH OF THAT CLUSTER AS WELL AS
ADDITIONAL STORM DEVELOPMENT MAY TRACK ACROSS THE NORTHWEST PORTION
OF OUR FORECAST AREA DURING THE LATE EVENING. IF STORMS CAN
DEVELOP...SEVERE POTENTIAL DOES EXIST AS 0-6 KM SHEAR OF 35-45 KNOTS
OVERSPREADS THE NORTHWEST PORTION OF OUR FORECAST AREA WITH THE MAIN
THREATS BEING SEVERE HAIL AND WIND.
REMAIN MORE CONFIDENT IN PRECIPITATION CHANCES AFTER 06Z WHEN
REMNANT CONVECTION FROM MISSOURI TRACKS TOWARDS THE AREA. SEVERE
THREAT WILL BE MINIMAL WITH THIS CONVECTION DUE TO ITS TIMING DURING
THE EARLY MORNING HOURS.
TUESDAY LOOKS TO BE COOLER THAN TODAY AS LITTLE SUN WILL BE SEEN
ACROSS OUR FORECAST AREA DUE TO CLOUD DEBRIS FROM FROM OVERNIGHT
CONVECTION AS WELL AS ADDITIONAL DYNAMIC LIFT FROM 40-50 KT LLJ.
SEVERE THREAT DOES EXIST IF A FEW BREAKS IN THE CLOUDS CAN PROVIDE
SIGNIFICANT SURFACE HEATING FOR EVEN MARGINAL SURFACE BASED
INSTABILITY. THE MAIN THREAT WILL BE LARGE HAIL AND DAMAGING WINDS
AS UNIDIRECTIONAL 35-40 KNOT SHEAR OVERSPREADS THE AREA.
&&
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
ONE OR TWO MORE ROUNDS OF CONVECTION TO BEGIN THE FORECAST PERIOD.
MODELS IN PRETTY GOOD AGREEMENT IN SHORT WAVE COMING OUT OF BASE OF
CLOSED LOW AND IMPACTING THE AREA TUE NIGHT. GOOD SUPPORT WILL
ACCOMPANY THIS FEATURE AND 50-60KT MID LEVEL SPEED MAX WILL COMBINE
WITH INFLUX OF LOW LEVEL MOISTURE WITH AT LEAST SUFFICIENT
INSTABILITY TO INITIATE OR MAINTAIN CONVECTION. UNIDIRECTIONAL WIND
PROFILE WITH AROUND 30KT OF SPEED SHEAR WILL HAVE DAMAGING WINDS AS
THE MAIN SEVERE THREAT. CLOSED LOW FINALLY OPENS UP AND WILL MOVE
EASTWARD INTO THE GREAT LAKES REGION WEDNESDAY NIGHT...BRINGING SFC
LOW AND MAIN COLD FRONT WITH IT. MODELS OFFERING VARYING
TIMING/PLACEMENT OF THESE FEATURES BUT ONE MORE ROUND OF CONVECTION
POSSIBLE WEDNESDAY...MAINLY FOR THE EASTERN HALF OF THE CWA. UPPER
TROF AXIS ROTATES THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY
KEEPING CHANCE FOR A FEW SHOWERS BEFORE COOLER DRIER CANADIAN HIGH
PRESSURE BEGINS TO BUILD INTO THE GREAT LAKES REGION ON FRIDAY. THIS
WILL PROVIDE A NICE START TO THE HOLIDAY WEEKEND...QUESTIONS REMAIN
AS TO WHETHER IT WILL LAST THROUGH MONDAY. SFC RIDGE AXIS WILL
PROGRESS EASTWARD SUNDAY AND MONDAY...PLACING OUR AREA ON THE
WESTERN PERIPHERY OF THE HIGH WHILE MEDIUM RANGE MODELS ATTEMPTING
TO BRING SHORT WAVE ENERGY DOWN IN NW FLOW. GETTING BETTER MODEL
AGREEMENT WITH THIS SOLN BUT LOTS OF VARIATION IN TIMING AND
PLACEMENT. ENSEMBLE GUIDANCE NEAR OR MOSTLY BELOW CLIMO FOR POPS AS
WELL SO WILL STILL HOLD OUT FOR DRY FORECAST FOR AT LEAST ONE MORE
ISSUANCE. TEMPS TRENDING SEASONABLY COOLER WITH AOB NORMAL FOR MOST
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...STEINWEDEL/KG
SHORT TERM...BENTLEY
LONG TERM...JAL
AVIATION/UPDATE...MURPHY
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AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
505 PM EDT SUN MAY 19 2013
.SYNOPSIS...
ISSUED AT 504 PM EDT SUN MAY 19 2013
SKIES WILL REMAIN MOSTLY CLEAR TO PARTLY CLOUDY TONIGHT...WITH LOW
TEMPERATURES MAINLY IN THE MID 60S. A LOW PRESSURE SYSTEM WILL MAKE
ITS WAY ACROSS THE REGION EARLY THIS WEEK...BRINGING CHANCES FOR
SHOWERS AND THUNDERSTORMS THROUGHOUT THE WEEK. TEMPERATURES ARE
EXPECTED TO BE FAIRLY WARM MONDAY AND TUESDAY BEFORE DROPPING DOWN
TO MORE SEASONABLE LEVELS BY THE END OF THE WEEK.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013
TIGHT DEWPOINT GRADIENT WHICH HAD BEEN EVER PERSISTENT ACROSS OUR
AREA HAS FINALLY BEEN ERRADICATED AS LOW TO MID 60S DEWPOINTS HAVE
NOW OVERSPREAD THE ENTIRE CWA. THIS INCREASE IN SURFACE DEWPOINTS
HAS YIELDED SBCAPE VALUES BETWEEN 1500 AND 2000 J/KG. WITH A LACK OF
ANY SIGNIFICANT FORCING...NOTHING MORE THAN A SCATTERED TO BROKEN CU
DECK HAS BEEN ABLE TO DEVELOP. THIS CU FIELD WILL DISSIPATE BY
LATE AFTERNOON AS A DEEP EML/CAPPING INVERSION OVERSPREADS THE CWA
FROM THE WEST.
PRECIP POTENTIAL FOR TONIGHT REMAINS COMPLICATED AS SIGNIFICANT
MODEL SPREAD EXISTS REGARDING THE LOCATION AND PERSISTENCE OF
REMNANT CONVECTION FROM IOWA/MISSOURI SEVERE WEATHER TODAY. GLOBAL
MODELS KEEP CONVECTION NORTHWEST OF OUR CWA...WHILE HI
RESOLUTION/CONVECTION ALLOWING MODELS BRING PRECIP INTO AT LEAST THE
WESTERN HALF OF THE CWA AFTER 05Z BEFORE COMPLETELY DISSIPATING.
KEPT SLIGHT CHANCE POPS IN THE NORTHWEST OVERNIGHT WITH THE ONLY
CHANGE BEING A SLIGHTLY EARLIER ARRIVAL TIME AS HRRR GUIDANCE IS
CONSISTENTLY BRINGING CONVECTION INTO WESTERN AREAS BETWEEN 03-04Z.
TEMPS WILL WARM INTO THE UPPER 80S ON MONDAY WITH A FEW LOCATIONS
LIKELY REACHING 90 DEGREES. THESE ABOVE NORMAL TEMPS COUPLED WITH
UPPER 60S TO NEAR 70 DEWPOINTS WILL MAKE THE MONDAY AIRMASS QUITE
UNSTABLE. KEPT POPS IN THE LOW CHANCE RANGE AS UNCERTAINTIES
REGARDING THE STRENGTH OF THE CAP AND ANY CONVECTIVE DEBRIS WHICH
MAY OVERSPREAD THE AREA LIMIT CONFIDENCE. IF CONVECTION CAN
DEVELOP...SEVERE POTENTIAL WILL INCREASE THROUGH TIME AS A 50-60 KT
MID-LEVEL JET STREAK CLIPS THE NORTHWEST PORTION OF OUR FORECAST
AREA NEAR 21Z AND IMPROVES THE SHEAR PROFILE.
&&
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013
FCST PERIOD TO BEGIN WITH SFC LOW AND VERTICALLY STACKED CLOSED
UPPER LOW OVER THE NORTHERN PLAINS/UPPER MIDWEST. BEST FOCUS AND
FORCING FOR CONVECTIVE INITIATION HEADING INTO MONDAY EVENING WILL
BE TO THE WEST OF OUR AREA DESPITE BEING IN A VERY UNSTABLE WARM
SECTOR WITH CAPES AOA 3000J/KG OVER MUCH OF THE CWA. 500MB RIDGE
SHIFTS EAST OF THE AREA MON NITE AND BREAKDOWN OF THICKNESS RIDGE
WILL PROVIDE AN OPPORTUNITY FOR CONVECTION TO WORK INTO THE WESTERN
CWA 06-12Z TUE. GOOD MOISTURE ADVECTION ON A 40-50KT LLJ ALONG WITH
A 50-60KT MID LEVEL SPEED MAX WILL ACCOMPANY SFC PRE-FRONTAL TROF ON
TUE BRINGING GOOD CONVECTIVE POTENTIAL INTO THE AREA. UNCERTAINTY
WILL BE IN ABILITY FOR DESTABILIZATION...PUTTING SEVERE POTENTIAL IN
QUESTION. MAIN SFC FRONT TO FOLLOW ON WED WHICH WILL KEEP LIKELY
POPS FOR SH/TSRA GOING DURING THE DAY. SECONDARY FRONT THEN SET TO
MOVE THRU ON THURSDAY BEFORE ENTIRE SYSTEM FINALLY KICKS EAST OF OUR
AREA AND SETS THE STAGE FOR A COOLER BUT PLEASANT START TO THE
MEMORIAL DAY WEEKEND AS CANADIAN HIGH PRESSURE BUILDS INTO THE GREAT
LAKES REGION ON FRI/SAT. GFS AND ECMWF TRENDING TOWARD A MUCH
DIFFERENT SOLN COMPARED TO EARLIER RUNS FOR THE REST OF THE HOLIDAY
WEEKEND. WHAT WAS ONCE AN AMPLIFIED NW FLOW PATTERN WITH A
RE-ENFORCING DRY CANADIAN AIRMASS IS NOW BEING OFFERED AS A
TRANSITION TO A MORE ZONAL PATTERN AND KICKING SHORTWAVE DISTURBANCE
INTO THE REGION AND A CHANCE FOR PRECIP SUNDAY. NOT EAGER TO BUY
INTO THIS SOLN JUST YET...ESPECIALLY GIVEN THAT EVEN THE HIGHER END
OF THE ENSEMBLE MEMBERS HAVE POPS BELOW CLIMO. THAT AND GIVEN ITS IN
DAY 7 WILL OPT TO CONTINUE WITH DRY FCST FOR NOW AND WAIT TO SEE IF
TREND CONTINUES AND STRONGER SIGNAL IN MODEL GUIDANCE PRESENTS
ITSELF.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 0220
PM EDT SUN MAY 19 2013
SCATTERED TO BROKEN CU FIELD HAS DEVELOPED ACROSS THE AREA THIS
AFTERNOON. THIS CU FIELD WILL DIMINISH OVER THE NEXT FEW HOURS AS
EML/CAPPING INVERSION ADVECTS INTO THE AREA. THIS CAP WILL KEEP BOTH
TERMINALS DRY DURING THE DAY. THERE IS A CHANCE OF THUNDERSTORMS AT
KSBN AFTER 05Z AS SEVERAL SHORT TERM MODELS INDICATE REMNANT
DISSIPATING CONVECTION FROM THE WEST MOVING ACROSS SOUTHERN LAKE
MICHIGAN. KEPT MENTION VCTS MENTION OUT OF THE 18Z TAF AND WILL
CONTINUE TO MONITOR TRENDS FOR POTENTIAL INCLUSION IN 00Z TAF. ANY
CONVECTION WHICH MAY MOVE INTO THE AREA SHOULD STAY NORTHWEST OF
KFWA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...KG
SHORT TERM...BENTLEY
LONG TERM...JAL
AVIATION...BENTLEY
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
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AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
322 PM EDT SUN MAY 19 2013
.SYNOPSIS...
ISSUED AT 1049 AM EDT SUN MAY 19 2013
HIGH PRESSURE CENTERED OFF OF THE NEW ENGLAND COAST WILL PROVIDE
SUNNY DRY WEATHER FOR TODAY. SOME CLOUDS FROM A LOW PRESSURE
SYSTEM IN THE CENTRAL PART OF THE COUNTRY WILL MOVE THROUGH TODAY
WITH TEMPERATURES ABOVE NORMAL. THAT LOW PRESSURE SYSTEM WILL MOVE
IN AND THROUGH THE REGION THROUGH THIS WEEK PROVIDING SHOWER AND
THUNDERSTORM CHANCES. TEMPERATURES THROUGH THE WEEK WILL GRADUALLY
COOL OFF AND BECOME MORE NORMAL BY WEEKS END.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013
TIGHT DEWPOINT GRADIENT WHICH HAD BEEN EVER PERSISTENT ACROSS OUR
AREA HAS FINALLY BEEN ERRADICATED AS LOW TO MID 60S DEWPOINTS HAVE
NOW OVERSPREAD THE ENTIRE CWA. THIS INCREASE IN SURFACE DEWPOINTS
HAS YIELDED SBCAPE VALUES BETWEEN 1500 AND 2000 J/KG. WITH A LACK OF
ANY SIGNIFICANT FORCING...NOTHING MORE THAN A SCATTERED TO BROKEN CU
DECK HAS BEEN ABLE TO DEVELOP. THIS CU FIELD WILL DISSIPATE BY
LATE AFTERNOON AS A DEEP EML/CAPPING INVERSION OVERSPREADS THE CWA
FROM THE WEST.
PRECIP POTENTIAL FOR TONIGHT REMAINS COMPLICATED AS SIGNIFICANT
MODEL SPREAD EXISTS REGARDING THE LOCATION AND PERSISTENCE OF
REMNANT CONVECTION FROM IOWA/MISSOURI SEVERE WEATHER TODAY. GLOBAL
MODELS KEEP CONVECTION NORTHWEST OF OUR CWA...WHILE HI
RESOLUTION/CONVECTION ALLOWING MODELS BRING PRECIP INTO AT LEAST THE
WESTERN HALF OF THE CWA AFTER 05Z BEFORE COMPLETELY DISSIPATING.
KEPT SLIGHT CHANCE POPS IN THE NORTHWEST OVERNIGHT WITH THE ONLY
CHANGE BEING A SLIGHTLY EARLIER ARRIVAL TIME AS HRRR GUIDANCE IS
CONSISTENTLY BRINGING CONVECTION INTO WESTERN AREAS BETWEEN 03-04Z.
TEMPS WILL WARM INTO THE UPPER 80S ON MONDAY WITH A FEW LOCATIONS
LIKELY REACHING 90 DEGREES. THESE ABOVE NORMAL TEMPS COUPLED WITH
UPPER 60S TO NEAR 70 DEWPOINTS WILL MAKE THE MONDAY AIRMASS QUITE
UNSTABLE. KEPT POPS IN THE LOW CHANCE RANGE AS UNCERTAINTIES
REGARDING THE STRENGTH OF THE CAP AND ANY CONVECTIVE DEBRIS WHICH
MAY OVERSPREAD THE AREA LIMIT CONFIDENCE. IF CONVECTION CAN
DEVELOP...SEVERE POTENTIAL WILL INCREASE THROUGH TIME AS A 50-60 KT
MID-LEVEL JET STREAK CLIPS THE NORTHWEST PORTION OF OUR FORECAST
AREA NEAR 21Z AND IMPROVES THE SHEAR PROFILE.
&&
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013
FCST PERIOD TO BEGIN WITH SFC LOW AND VERTICALLY STACKED CLOSED
UPPER LOW OVER THE NORTHERN PLAINS/UPPER MIDWEST. BEST FOCUS AND
FORCING FOR CONVECTIVE INITIATION HEADING INTO MONDAY EVENING WILL
BE TO THE WEST OF OUR AREA DESPITE BEING IN A VERY UNSTABLE WARM
SECTOR WITH CAPES AOA 3000J/KG OVER MUCH OF THE CWA. 500MB RIDGE
SHIFTS EAST OF THE AREA MON NITE AND BREAKDOWN OF THICKNESS RIDGE
WILL PROVIDE AN OPPORTUNITY FOR CONVECTION TO WORK INTO THE WESTERN
CWA 06-12Z TUE. GOOD MOISTURE ADVECTION ON A 40-50KT LLJ ALONG WITH
A 50-60KT MID LEVEL SPEED MAX WILL ACCOMPANY SFC PRE-FRONTAL TROF ON
TUE BRINGING GOOD CONVECTIVE POTENTIAL INTO THE AREA. UNCERTAINTY
WILL BE IN ABILITY FOR DESTABILIZATION...PUTTING SEVERE POTENTIAL IN
QUESTION. MAIN SFC FRONT TO FOLLOW ON WED WHICH WILL KEEP LIKELY
POPS FOR SH/TSRA GOING DURING THE DAY. SECONDARY FRONT THEN SET TO
MOVE THRU ON THURSDAY BEFORE ENTIRE SYSTEM FINALLY KICKS EAST OF OUR
AREA AND SETS THE STAGE FOR A COOLER BUT PLEASANT START TO THE
MEMORIAL DAY WEEKEND AS CANADIAN HIGH PRESSURE BUILDS INTO THE GREAT
LAKES REGION ON FRI/SAT. GFS AND ECMWF TRENDING TOWARD A MUCH
DIFFERENT SOLN COMPARED TO EARLIER RUNS FOR THE REST OF THE HOLIDAY
WEEKEND. WHAT WAS ONCE AN AMPLIFIED NW FLOW PATTERN WITH A
RE-ENFORCING DRY CANADIAN AIRMASS IS NOW BEING OFFERED AS A
TRANSITION TO A MORE ZONAL PATTERN AND KICKING SHORTWAVE DISTURBANCE
INTO THE REGION AND A CHANCE FOR PRECIP SUNDAY. NOT EAGER TO BUY
INTO THIS SOLN JUST YET...ESPECIALLY GIVEN THAT EVEN THE HIGHER END
OF THE ENSEMBLE MEMBERS HAVE POPS BELOW CLIMO. THAT AND GIVEN ITS IN
DAY 7 WILL OPT TO CONTINUE WITH DRY FCST FOR NOW AND WAIT TO SEE IF
TREND CONTINUES AND STRONGER SIGNAL IN MODEL GUIDANCE PRESENTS
ITSELF.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 0220
PM EDT SUN MAY 19 2013
SCATTERED TO BROKEN CU FIELD HAS DEVELOPED ACROSS THE AREA THIS
AFTERNOON. THIS CU FIELD WILL DIMINISH OVER THE NEXT FEW HOURS AS
EML/CAPPING INVERSION ADVECTS INTO THE AREA. THIS CAP WILL KEEP BOTH
TERMINALS DRY DURING THE DAY. THERE IS A CHANCE OF THUNDERSTORMS AT
KSBN AFTER 05Z AS SEVERAL SHORT TERM MODELS INDICATE REMNANT
DISSIPATING CONVECTION FROM THE WEST MOVING ACROSS SOUTHERN LAKE
MICHIGAN. KEPT MENTION VCTS MENTION OUT OF THE 18Z TAF AND WILL
CONTINUE TO MONITOR TRENDS FOR POTENTIAL INCLUSION IN 00Z TAF. ANY
CONVECTION WHICH MAY MOVE INTO THE AREA SHOULD STAY NORTHWEST OF
KFWA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...LOTHAMER
SHORT TERM...BENTLEY
LONG TERM...JAL
AVIATION...BENTLEY
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AREA FORECAST DISCUSSION
NWS DES MOINES IA
1152 PM CDT SAT MAY 18 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 330 PM CDT SAT MAY 18 2013
MAIN CONCERNS TONIGHT WILL BE EXTENT OF CONVECTION ACROSS THE
FORECAST AREA LATE NIGHT AND INTO EARLY MORNING. MODELS SIMILAR IN
TIMING BUT VERY LITTLE AGREEMENT IN AREAL COVERAGE/PLACEMENT OF
RAINFALL OVERNIGHT SO CONFIDENCE LOW AT THIS TIME. SYNOPTIC SETUP
SHOWS APPROACHING H700 SHORTWAVE OVER PANHANDLE AREA OF TEXAS/OK
NOW AND SIMPLE TIME OF ARRIVAL TOOL SHOWS AT CURRENT SPEED WILL
ARRIVE INTO SW COUNTIES AFT 07Z AND INTO CENTRAL IOWA BY ABOUT
10Z...FAVORED TIME FOR NOCTURNAL CONVECTION. THIS CORRELATES
PRETTY WELL WITH INCREASING WIND FIELDS FROM THE GFS OVERNIGHT
WITH H850 40KT JET ENTERING AREA AND SUFFICIENT SPEED SHEAR FROM
H700/H500 OF 40-60KTS RESPECTIVELY FROM 08-12Z. SFC BOUNDARY LOOKS
TO MAKE IT AS FAR NORTH AS IA/MO BORDER BY 12Z AS WELL. MOISTURE
IS QUITE HIGH FOR THIS EVENT WITH PWATS BY 12Z APPROACHING +90-95%
LEVEL OF CLIMATOLOGICAL MAX AND NEAR 2 STANDARD DEVIATIONS FROM
NORMAL. WARM CLOUD DEPTHS LOOK FAIRLY IMPRESSIVE WITH 10-11KFT
EXPECTED LATE TONIGHT AND A GOOD SHARE OF SUNDAY AS WELL. WITH
EXPECTED SHORT WAVE AND FORECAST CONDITIONS...HAVE SOME CONCERNS
ABOUT LOCALLY HEAVY RAINFALL AND POTENTIAL FOR ISOLATED FLASH
FLOODING OVER THE WEST/SOUTHWEST AREAS SHOULD MCS HOLD TOGETHER AS
IT TRACKS NORTHEAST. CURRENT 3 HR GRIDDED FLASH FLOOD GUIDANCE OF
+2-3 INCHES REMAINS PRETTY HIGH OVER MUCH OF SOUTHERN 2 TIER
COUNTIES...BUT WEST OF I35 AND AREAS NORTH OF THERE HAVE LOWER
VALUES OF 1.75 TO 2 INCHES IN GENERAL. WITH HIGH PWATS AND
SIGNIFICANT WARM CLOUD DEPTHS COMBINED WITH SHORT WAVE WE CLOUD
SEE ISOLATED RAINFALL AMOUNTS OF 1 TO 2+ INCHES OVER THE SOUTHWEST
TO CENTRAL COUNTIES BY 12Z...WITHIN TRACK OF MCS. THE CHALLENGE
REMAINS HOWEVER...IN THAT THE 4 KM WRF AND HRRR WILL NEED TO WATCH
THIS THROUGH EVENING TO SEE HOW SITUATION EVOLVES. LOWS OVERNIGHT
WILL BE QUITE MILD AGAIN WITH INCREASING MOISTURE PUTTING A CAP ON
MINS IN THE LOWER TO MID 60S. SOME CONCERN REMAINS ABOUT POTENTIAL
FOR SEVERE OVERNIGHT...BUT IF ANY OCCURS WILL BE MAINLY FOR LARGE
HAIL OVER THE WEST.
.LONG TERM.../SUNDAY THROUGH SATURDAY/...
ISSUED AT 330 PM CDT SAT MAY 18 2013
MAIN FORECAST CONCERN REMAINS FOCUSED ON ACTIVE WEATHER PATTERN
DEVELOPING OVER THE NEXT SEVERAL DAYS. MODELS IN GOOD AGREEMENT
THROUGH EARLY IN THE WEEK WITH CUTOFF LOW LINGERING THROUGH
THURSDAY. LEANED A BLEND OF THE NAM12 AND ARW-WRF FOR TIMING AND
TRENDS TOMORROW INTO TOMORROW NIGHT...THEN A GFS/ECMWF THROUGH
MIDWEEK.
.SUNDAY INTO MONDAY...STRONG 500MB TROUGH DIGS INTO THE CENTRAL
PLAINS TONIGHT AND SLOWLY MAKE ITS WAS INTO THE MIDWEST BY TOMORROW.
FIRST SHORTWAVE THAT MAY SPAWN THUNDERSTORMS OVERNIGHT TONIGHT
LINGERS INTO NORTHERN IOWA THROUGH SUNDAY MORNING AND DIMINISH AS
THE LLJ DECREASES. DECREASED POPS ACROSS THE SOUTH CONSIDERABLY
UNTIL THE LATE AFTERNOON BEFORE REDEVELOPMENT BY THE AFTERNOON
BEFORE NEXT SHORTWAVE EJECTS ACROSS THE CENTRAL PLAINS AND INTO
MO/IA BY 00Z MONDAY.
DESTABILIZATION OCCURS LATE SUNDAY MORNING AND INTO THE AFTERNOON
AS THE 0-3KM ML CAPE INCREASES TO 800 TO NEAR 2000 J/KG OVER
CENTRAL AND SOUTHERN IOWA BY 00Z MONDAY WITH BREAK BETWEEN
SHORTWAVES. SURFACE BASED CAPE INCREASES TO OVER 2500 J/KG BY THE
SAME TIME AND LOCATION. LOW LEVEL SHEAR MORE FAVORABLE FOR
TORNADIC DEVELOPMENT ACROSS FAR SOUTHWEST IOWA WHERE 0-1KM SHEAR
INCREASE TO 20-25 KNOTS...MORE IN THE 10 TO 15 KNOTS RANGE FURTHER
NORTH. DEEP LAYER SHEAR FAVORABLE FOR LONG LIVED STORMS LATE
TOMORROW AFTERNOON INTO THE EVENING HOURS. KEPT MENTION OF SEVERE
WX FOR SOUTHERN PORTIONS OF THE FORECAST AREA SUNDAY LATE
AFTERNOON AND INTO THE EVENING. IN ADDITION TO SEVERE
POTENTIAL...HEAVY RAIN LOOKS IMMINENT AS WELL WITH WARM LAYER
CLOUD DEPTHS RANGING AROUND 11000 FEET AND PRECIPITABLE WATER
VALUES IN THE 1.5 TO 1.75 INCH RANGE. CORFIDI VECTORS INDICATING
TRAINING STORMS TOMORROW NIGHT LEADING TO FLASH FLOODING
POTENTIAL. STORMS LOOK TO PUSH INTO NORTHERN IOWA EARLY MONDAY
MORNING AND LOWERED POPS IN CENTRAL AND SOUTHERN IOWA.
.TUESDAY THROUGH SATURDAY...UPPER LOW BECOMES CUTOFF AND LINGERS
OVER THE REGION BEFORE FINALLY MOVES EAST BY THURSDAY MORNING.
SEVERE WEATHER CHANCES LOOK MINIMAL...BUT ADDITIONAL PERIODS OF RAIN
ARE LIKELY INTO THURSDAY. TEMPERATURES LOOK TO BE NEAR OR SLIGHTLY
BELOW NORMAL BY WEDNESDAY AND THROUGH LATE IN THE WEEK.
&&
.AVIATION...19/06Z
ISSUED AT 1152 PM CDT SAT MAY 18 2013
LINE OF STORMS BEGINNING TO CROSS THE IA/NE BORDER WITH A SECOND
SEGMENT COMING UP FROM KS. THE LINE OF STORMS OVER NE SHOULD WEAKEN
WHILE THE STORMS OVER KS SHOULD LIFT ACROSS CENTRAL IOWA THROUGH
12-15Z. HEAVY RAIN POTENTIAL WITH THESE STORMS AS WELL AS AN
ISOLATED STRONG WIND OR LARGE HAIL THREAT BUT STORMS WILL BE LIFTING
INTO A LITTLE LESS FAVORABLE AIR. I AM EXPECTING A BREAK FROM
15Z-19Z BUT HOW FAST WE BREAK OUT OF THE CLOUDS AND DESTABILIZE WILL
PLAY A ROLE IN HOW QUICKLY STORMS REDEVELOP. A STRONG UPPER LEVEL
FEATURE WILL MOVE IN BY 21Z AND SWING NE THROUGH THE END OF THE TAF
PERIOD BRINGING ANOTHER ROUND OF THUNDERSTORMS...SOME WITH THE
POTENTIAL FOR DAMAGING WIND AND LARGE HAIL. THE BEST THREAT WOULD
BE OVER KDSM WITH KOTM AND KFOD ON THE FRINGE OF THE THREAT AREA.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...FAB
AREA FORECAST DISCUSSION
NWS TOPEKA KS
614 PM CDT MON MAY 20 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 350 PM CDT MON MAY 20 2013
LATEST MESO ANALYSIS AT 19Z SHOWS A COUPLE OF FRONTS IN AND NEAR OUR
CWA. FIRST IS OFF TO THE WEST ACROSS CENTRAL KANSAS WITH THE OTHER
EXTENDING FROM NORTH CENTRAL OKLAHOMA INTO FAR SOUTHERN EAST CENTRAL
KANSAS SOUTH OF I-35. MOISTURE CONVERGENCE WAS NOTED ALONG BOTH OF
THE BOUNDARIES WITH THE STRONGEST ALONG THE SOUTHERN COUNTIES. BULK
SHEAR VALUES ARE STRONG ACROSS MUCH OF THE AREA WITH HIGHEST
INSTABILITY ACROSS SOUTHEAST KANSAS INTO EAST CENTRAL KANSAS.
0-1 KM STORM RELATIVE HELICITY AROUND 100 TO 120 M2/S2 ACROSS
SOUTHEAST AND EAST CENTRAL KANSAS. WINDS ARE BACKED SLIGHTLY IN THE
LOW LEVELS ALONG AND SOUTH OF I-35. ISOLATED TORNADO THREAT WILL
CONTINUE ALONG AND SOUTHEAST OF I-35 THROUGH MID EVENING.
HRRR AND RAP DEVELOP SCATTERED CONVECTION ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS LATE THIS AFTERNOON AND EVENING. ALSO WATER VAPOR
SHOWS A MID LEVEL WAVE MOVING ACROSS SOUTHWEST KANSAS THIS WILL BE
COUPLED WITH ENERGY ROTATING AROUND THE NORTHERN PLAINS UPPER LOW
ACROSS NEBRASKA AND NORTH CENTRAL NEBRASKA THIS EVENING. WILL
CONTINUE WITH EVENING CHANCES OF THUNDERSTORMS ACROSS NORTH CENTRAL
AND NORTHEAST KANSAS. HIGHEST CHANCES WILL BE ALONG AND SOUTH OF
I-35. PRECIPITATION SHOULD MOVE OFF TO THE SOUTHEAST LATER TONIGHT
AS THE COOL FRONT MOVES EASTWARD. LOWS TONIGHT WILL BE IN THE 50S.
TUESDAY SHOULD BE RELATIVELY DRY ACROSS MUCH OF THE FORECAST AREA
SAVE THE FAR SOUTHEAST COUNTIES OF EAST CENTRAL KANSAS. BEST FORCING
WILL BE FOCUSED FURTHER SOUTH TUESDAY FROM OKLAHOMA INTO SOUTHERN
MISSOURI. HIGHS WILL BE IN THE MID 70S TUESDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 350 PM CDT MON MAY 20 2013
LAST SHORTWAVE LOBE ON THE SOUTHERN PORTIONS OF THE UPPER LOW WILL
ROTATE SOUTHEAST OF THE COUNTY WARNING AREA TUESDAY NIGHT...SO
WILL CONTINUE WITH A DRY FCST TUESDAY NIGHT ON INTO THURSDAY AS
THE UPPER LOW SETTLES INTO THE EASTERN CONUS. BY THURSDAY NIGHT
INTO FRIDAY...INCREASING MOISTURE AND WARM AIR ADVECTION WILL TAKE
PLACE ON THE EASTERN SIDE OF BUILDING UPPER LEVEL RIDGE. WILL
INTRODUCE POPS AGAIN AT THAT TIME AND PERSIST THROUGH THE WEEKEND
AS WEAK SHORTWAVES MOVE THROUGH THE FLOW AND INTO THE RIDGE AXIS
NEAR THE COUNTY WARNING AREA. THIS WARRANTS KEEPING CONVECTIVE
POTENTIAL GOING THROUGH THE PERIOD...ALTHOUGH MODELS TRENDS ARE
HINTING THAT AN AMPLIFICATION OF THE UPPER RIDGE INTO EARLY NEXT
WEEK MAY FORCE THE STRONGER FLOW ALOFT AND HIGHER PRECIP CHANCES A
LITTLE FURTHER NORTH WITH IT. EITHER WAY...A GRADUAL WARMING TREND
STILL LOOKS ON TRACK AS WELL WITH HIGHS WARMING FROM MAINLY THE
70S WEDNESDAY INTO FRIDAY...THEN INTO THE LOW TO MIDDLE 80S FOR
THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 613 PM CDT MON MAY 20 2013
FOR 00Z TAFS...VFR CONDITIONS EXPECTED THROUGH THE PERIOD AS THE
LINGERING LOW PRESSURE SYSTEM FINALLY PROGRESSES FURTHER EAST OF THE
AREA. WITH THE ASSOCIATED COLD FRONT TRACKING EASTWARD ACROSS THE
TAF SITES...LATEST OBSERVATIONS SHOW WINDS BEGINNING TO SHIFT TO OUT
OF THE WEST AND WEST SOUTHWEST. EXPECT THIS LIGHT WESTERLY FLOW TO
PERSIST TONIGHT INTO TOMORROW...ALONG WITH SOME SCATTERED LOW/MID
CLOUDS.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...53
LONG TERM...63
AVIATION...HENNECKE
AREA FORECAST DISCUSSION
NWS TOPEKA KS
120 PM CDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 118 PM CDT SUN MAY 19 2013
ADJUSTED CONVECTIVE TIMING FOR THE FIRST FEW HOURS OF THE
AFTERNOON. HIGH-RES SHORT TERM MODELS SHOW ELEVATED THUNDERSTORMS
DEVELOPING ACROSS NORTH CENTRAL AND NORTHEAST KANSAS THIS AFTERNOON.
RADAR AT 1250 PM WAS SHOWING DEVELOPING CELLS NEAR JUNCTION CITY
AND ANOTHER AREA IN SOUTH CENTRAL KANSAS. BULK SHEAR NEAR 30 KTS
ACROSS NORTH CENTRAL KANSAS AND 40 TO 50 KTS IN EAST CENTRAL AND
SOUTHEAST KANSAS. CAPE WAS AVERAGING AROUND 1000 J/KG NEAR THE
NEBRASKA BORDER TO NEAR 3000 J/KG IN SOUTH CENTRAL KANSAS. EXPECT
STORMS TO DEVELOP IN SOUTH CENTRAL KANSAS THEN MOVE NORTHEAST INTO
EAST CENTRAL KANSAS AFTER 20Z WITH ELEVATED STORMS CONTINUING
ACROSS MUCH OF NORTH CENTRAL AND PARTS OF NORTHEAST KANSAS. MID
LEVEL LAPSE RATES WILL STEEPEN WITH TIME (8-9 DEG) AS THE UPPER
WAVE/TROUGH MOVES NORTHEAST. SHEAR AND INSTABILITY WILL BE
SUPPORTIVE OF SUPER CELLS THIS AFTERNOON. LARGE HAIL AND DAMAGING
WINDS WILL BE THE MAIN HAZARDS WITH ISOLATED TORNADOES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SUN MAY 19 2013
SHORT TERM FORECAST (SUNDAY AND SUNDAY NIGHT)...
THE POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EVENT REMAINS IN TACT
FOR SUNDAY ACROSS ALL OF EASTERN KANSAS...WITH ALL HAZARDS OF SEVERE
WEATHER POSSIBLE INCLUDING LARGE DAMAGING HAIL...STRONG WINDS...AND
PERHAPS A TORNADO OR TWO.
THE INITIAL SURFACE OBSERVATION MAP INDICATES A RATHER WORKED OVER
LOW LEVEL ATMOSPHERE IN THE WAKE OF STRONG STORMS WHICH HAVE SINCE
LEFT THE AREA. PREVIOUS AS WELL AS ONGOING CONVECTION WILL LIKELY
CREATE AN OUTFLOW BOUNDARY IN THE KS/OK BORDER REGION...WHICH MAY
PLAY A ROLE IN THUNDERSTORM DEVELOPMENT AND BEHAVIOR FOR SUNDAY.
CURRENTLY LIGHT RAIN ASSOCIATED WITH POST OFB OVER RUNNING REMAIN IN
THE AREA...MAINLY ACROSS SOUTHERN KANSAS. DEPENDING ON HOW MUCH
SKIES CAN CLEAR ON SUNDAY WILL HELP DETERMINE HOW MUCH THE
ATMOSPHERE WILL BE ABLE TO DESTABILIZE FOR SUNDAY AFTERNOON. WATER
VAPOR IMAGERY AS WELL AS RAP40 H5 ANALYSIS INDICATE THE STRONG MID
LEVEL TROUGH...PARTIALLY RESPONSIBLE FOR SATURDAYS
CONVECTION...REMAINS IN PLACE OVER THE HIGH PLAINS AS IT GRADUALLY
MOVES EAST. AS THE DAY PROGRESSES H5 HEIGHT FALLS WILL BE PREVALENT
ACROSS THE AREA. WITH A MOIST BOUNDARY LAYER IN PLACE...ALONG WITH A
POTENT MID LEVEL TROUGH MOVING THROUGH THE AREA...EXPECT A PERIOD OF
SEVERE WEATHER TO TAKE PLACE LATER TODAY ACROSS EASTERN KANSAS.
ALL HIGH RESOLUTION SHORT RANGE MODELS PROG A QUICK RECOVERY OF THE
BOUNDARY LAYER MOISTURE AHEAD OF A DEEPENING SURFACE LOW COMING OFF
THE SOUTHERN/CENTRAL HIGH PLAINS. STRONG SOUTHERLY SFC FLOW WILL AID
IN THE BOUNDARY LAYER MOISTURE RECOVERY THROUGH THE MORNING AND
EARLY AFTERNOON HOURS ON SUNDAY. AN INITIAL ROUND OF ELEVATED
THUNDERSTORMS WILL BE POSSIBLE LATE SUNDAY MORNING...MAINLY NORTH OF
INTERSTATE 70 AS WARM AIR ADVECTION RIDES OVER THE LOW LEVEL
INVERSION. AROUND 2000-3000 J/KG OF ELEVATED INSTABILITY WILL BE
PRESENT AS WELL AS AROUND 40 KTS OF DEEP LAYER SHEAR FOR ANY STORM
TO TAP INTO...SO ROBUST UPDRAFTS CAPABLE OF PRODUCING MAINLY LARGE
HAIL WILL BE POSSIBLE IN THIS INITIAL ROUND OF THUNDERSTORMS LATE
SUNDAY MORNING INTO THE EARLY AFTERNOON. SOUTH OF THE AREA OF THE
MORNING THUNDERSTORMS THE BOUNDARY LAYER SHOULD BE ABLE TO
DESTABILIZE RAPIDLY THROUGHOUT THE DAY...SETTING THE STAGE FOR THE
MAIN PERIOD OF SEVERE THUNDERSTORMS.
MESOSCALE DETAILS WILL LIKELY NEED TO BE IRONED OUT THROUGHOUT THE
DAY TO DETERMINE THE TIMING AND STRENGTH OF THE STRONGEST STORMS FOR
THE AREA. 06Z RAP FORECAST OF SURFACE THETA E AND WIND DIRECTION
SHOWS A GOOD PUNCH OF DRY AIR COMING OFF THE SOUTHERN HIGH PLAINS
INTO THE WICHITA METRO AREA. THE EXACT LOCATION OF THIS DRY PUNCH
AND STRONG SURFACE WIND CONVERGENCE IS A LITTLE UNCERTAIN...BUT THAT
WOULD BE ONE OF THE FOCI FOR STORM DEVELOPMENT THIS AFTERNOON.
ANOTHER FACTOR IN FAVOR OF ROBUST CONVECTION ACROSS THE AREA IS THE
PRESENCE OF A VERY POTENT UPPER LEVEL JET...WHICH NOSES INTO SE
KANSAS...PUTTING THE CONVECTIVELY FAVORABLE LEFT EXIT REGION RIGHT
OVER THE FORECAST AREA. GIVEN THESE FACTORS IT APPEARS CONCEIVABLE
THAT A FEW STORMS WILL BE ABLE TO INITIATE 20-21Z IN THE
AFOREMENTIONED STRONG CONVERGENCE ZONE AND PUSH NORTHEAST UTILIZING
3500-4500 ML CAPE AND PERHAPS 40 TO 50 KTS OF DEEP LAYER SHEAR.
EXTREME MID LEVEL LAPSE RATES ON THE ORDER OF 9-9.5 C/KM WILL AID IN
CREATING THE EXTREME ML CAPE...SO ANY UPDRAFT THAT GOES UP DURING
PEAK HEATING WILL LIKELY BE ABLE TO PRODUCE LARGE HAIL...ON THE
ORDER OF BASEBALL SIZED...WITH PERHAPS SOME LARGER STONES. OF COURSE
WITH ANY STORM THAT BECOMES SURFACE BASED STRONG OUTFLOW WINDS WILL
ALWAYS BE PROBABLE...SO AREAS IN THE VICINITY OF THE STRONGEST
STORMS COULD SEE STRONG GUSTY WINDS ON THE ORDER OF 60 TO 70 MPH.
INITIAL STORM COVERAGE WILL LIKELY BE DICTATED BY DETAILED MESOSCALE
INFLUENCES AND COULD BE ISOLATED TO SCATTERED IN NATURE...HOWEVER
ONCE THE MAIN MID LEVEL SYSTEM CAN MOVE INTO THE AREA COVERAGE WILL
INCREASE...WITH DISCREET STORMS HAVING THE BEST CHANCE TO PRODUCE
LARGE HAIL...STRONG WINDS AND PERHAPS A TORNADO.
REGARDING THE TORNADO THREAT...GIVEN THE EXTREME INSTABILITY PRESENT
FOR THESE STORMS AND THE STRONG SHEAR IT CANNOT BE RULED OUT THAT A
TORNADO OR TWO COULD FORM. GIVEN THAT SURFACE WINDS WILL BE OUT OF
THE SSE AND LOW/MID LEVEL WINDS WILL BE VEERING WITH HEIGHT THE
GENERAL WIND SHEAR PROFILE WILL BE IN PLACE TO WARRANT A TORNADO
THREAT. FORECAST HODOGRAPHS FOR NUMEROUS STRONG TORNADOES ARE FAR
FROM PERFECT IN THIS SET UP...AS THE HODOGRAPHS LACK THE OPTIMAL
LOOPING CLOCKWISE STRUCTURE. WIND PROFILES DO LOOK A BIT BETTER WITH
THE LATEST RUNS OF THE MODELS THAN BEFORE...BUT STILL TAKE ON A BIT
OF AN S-SHAPE WITH COUNTERCLOCKWISE STRUCTURE. A PLANAR VIEW OF THE
LOW LEVEL WIND SHEAR SHOWS THAT ENOUGH TURNING WILL TAKE PLACE IN
THE LOWEST 1-3 KM TO CONTINUE A CONCERN FOR TORNADIC
BEHAVIOR...ESPECIALLY ONCE THE EARLY EVENING SETS IN AND THE LOW
LEVEL JET CAN INCREASE...LENGTHENING THE LOWEST LEVEL OF THE
HODOGRAPH. THE BOTTOM LINE IS THAT ALTHOUGH THE WIND SHEAR PROFILE
IS NOT PERFECT FOR STRONG TORNADOES TO OCCUR THERE IS ENOUGH OF A
SIGNAL FOR TORNADIC POTENTIAL TO WARRANT CONCERN FOR A DISCREET
STORM OR TWO TO PRODUCE A TORNADO...PERHAPS STRONG...ESPECIALLY IF A
BOUNDARY COMES INTO PLAY.
AS THE DAY WEARS ON STORM COVERAGE WILL LIKELY INCREASE AS THE MID
LEVEL TROUGH MOVES INTO THE AREA PROVIDING AMPLE ASCENT AND SUPPORT
FOR DEEP CONVECTION. ALSO MOVING THROUGH THE AREA IS A COLD FRONT
WHICH WILL ALSO AID IN INCREASING STORM COVERAGE AS IT PUSHES
THROUGH THE AREA. EXPECT A TRANSITION TO MCS/SQUALL LINE LATER IN
THE DAY AS STORMS INTERACT WITH EACH OTHER...EVENTUALLY CLEARING
THROUGH THE AREA OVERNIGHT SUNDAY NIGHT INTO MONDAY.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CDT SUN MAY 19 2013
MON-TUES...HAVE KEPT LINGERING OVERNIGHT POPS WEIGHTED TOWARD THE
EAST AS WILL HAVE TO SEE HOW EVENING CONVECTION UNFOLDS SUNDAY.
LEAD RIPPLE IN THE BIGGER LONGWAVE TROF APPEARS TO MOVE NE INTO
IOWA BY 12Z MONDAY AND WOULD EXPECT SOME CLEARING FROM WEST TO
EAST BY MORNING. BRUNT OF THE LONGWAVE TROF STILL POISED TO THE
WEST OF THE AREA HOWEVER...AND JET STREAK ROUNDS THE BASE OVER
EASTERN KS BY THE NOON HOUR MONDAY. THIS HELPS KEEP THE FRONT OVER
SOUTHEAST KANSAS. BY 06Z TUESDAY...THE RRE OF THE UPPER JET AND
BROAD LIFT FROM THE UPPER TROF MOVE OUT OVER THE FRONT ONCE
AGAIN...AND FIRES OFF MORE STORMS OVER SOUTHEAST KANSAS. THESE
STORMS WOULD BE SEVERE AS GOOD INSTABILITY AND SHEAR REMAIN IN
PLACE. THE BEST FOCUS FOR SEVERE LOOKS TO BE JUST SE OF THE
TOPEKA COUNTIES WITH A SLIGHT RISK ACROSS THE SOUTHEAST HALF. SOME
DETAIL DEPENDS ON MORE MESOSCALE MECHANISMS AND FORECAST LOCATION
MAY ADJUST SOMEWHAT BETWEEN NOW AND MONDAY...BUT FOR THOSE ALONG
AND SE OF I35 STAY TUNED FOR POSSIBLY MORE SEVERE WEATHER LATE
MONDAY. PRECIP CHANCES DIMINISH AFTER SUNRISE TUESDAY AND POPS
REFLECT THIS TREND. HIGHS BY TUESDAY ONLY ANTICIPATED TO BE IN THE
70S AS COOLER TEMPS FROM THE NW OVERTAKE THE CENTRAL PLAINS.
WED-SAT ANTICIPATE COOLER THAN NORMAL HIGH TEMPERATURES AS UPPER
TROF IS SLOW TO MOVE OFF TO THE EAST AND SURFACE HIGH PRESSURE
PUSHES INTO THE PLAINS BEHIND THE SYSTEM INTO THE END OF THE WEEK.
SW FLOW REESTABLISHES OVER THE SW STATES...AND FRONT IN BETWEEN
GENERATES SHOWERS AND THUNDER AT TIMES OVER THE SOUTHEAST COUNTIES.
WILL CARRY SOME POPS A BIT HIGHER TO THE SW AS A RESULT. GENERALLY
ANTICIPATE DAYTIME HIGHS IN THE 70S WITH OVERNIGHT LOWS IN THE
50S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 118 PM CDT SUN MAY 19 2013
VFR CONDITIONS EXPECTED OUTSIDE OF CONVECTION. TIMING OF TSRA INTO
THE TERMINALS WITH MHK IN THE 19Z-20Z TIME FRAME AND TOP AND FOE
AROUND 22Z. WITH SCATTERED TSRA EXPECTED HAVE INCLUDED MVFR CIGS
AND VSBYS IN TAFS THROUGH 02Z. WINDS WILL CONTINUE TO BE GUSTY OUT
OF THE SOUTH THROUGH THE THE EARLY EVENING THEN DECREASE AFTER 02Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...53
SHORT TERM...LEIGHTON
LONG TERM...CRAVEN
AVIATION...53
AREA FORECAST DISCUSSION
NWS TOPEKA KS
733 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SUN MAY 19 2013
SHORT TERM FORECAST (SUNDAY AND SUNDAY NIGHT)...
THE POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EVENT REMAINS IN TACT
FOR SUNDAY ACROSS ALL OF EASTERN KANSAS...WITH ALL HAZARDS OF SEVERE
WEATHER POSSIBLE INCLUDING LARGE DAMAGING HAIL...STRONG WINDS...AND
PERHAPS A TORNADO OR TWO.
THE INITIAL SURFACE OBSERVATION MAP INDICATES A RATHER WORKED OVER
LOW LEVEL ATMOSPHERE IN THE WAKE OF STRONG STORMS WHICH HAVE SINCE
LEFT THE AREA. PREVIOUS AS WELL AS ONGOING CONVECTION WILL LIKELY
CREATE AN OUTFLOW BOUNDARY IN THE KS/OK BORDER REGION...WHICH MAY
PLAY A ROLE IN THUNDERSTORM DEVELOPMENT AND BEHAVIOR FOR SUNDAY.
CURRENTLY LIGHT RAIN ASSOCIATED WITH POST OFB OVER RUNNING REMAIN IN
THE AREA...MAINLY ACROSS SOUTHERN KANSAS. DEPENDING ON HOW MUCH
SKIES CAN CLEAR ON SUNDAY WILL HELP DETERMINE HOW MUCH THE
ATMOSPHERE WILL BE ABLE TO DESTABILIZE FOR SUNDAY AFTERNOON. WATER
VAPOR IMAGERY AS WELL AS RAP40 H5 ANALYSIS INDICATE THE STRONG MID
LEVEL TROUGH...PARTIALLY RESPONSIBLE FOR SATURDAYS
CONVECTION...REMAINS IN PLACE OVER THE HIGH PLAINS AS IT GRADUALLY
MOVES EAST. AS THE DAY PROGRESSES H5 HEIGHT FALLS WILL BE PREVALENT
ACROSS THE AREA. WITH A MOIST BOUNDARY LAYER IN PLACE...ALONG WITH A
POTENT MID LEVEL TROUGH MOVING THROUGH THE AREA...EXPECT A PERIOD OF
SEVERE WEATHER TO TAKE PLACE LATER TODAY ACROSS EASTERN KANSAS.
ALL HIGH RESOLUTION SHORT RANGE MODELS PROG A QUICK RECOVERY OF THE
BOUNDARY LAYER MOISTURE AHEAD OF A DEEPENING SURFACE LOW COMING OFF
THE SOUTHERN/CENTRAL HIGH PLAINS. STRONG SOUTHERLY SFC FLOW WILL AID
IN THE BOUNDARY LAYER MOISTURE RECOVERY THROUGH THE MORNING AND
EARLY AFTERNOON HOURS ON SUNDAY. AN INITIAL ROUND OF ELEVATED
THUNDERSTORMS WILL BE POSSIBLE LATE SUNDAY MORNING...MAINLY NORTH OF
INTERSTATE 70 AS WARM AIR ADVECTION RIDES OVER THE LOW LEVEL
INVERSION. AROUND 2000-3000 J/KG OF ELEVATED INSTABILITY WILL BE
PRESENT AS WELL AS AROUND 40 KTS OF DEEP LAYER SHEAR FOR ANY STORM
TO TAP INTO...SO ROBUST UPDRAFTS CAPABLE OF PRODUCING MAINLY LARGE
HAIL WILL BE POSSIBLE IN THIS INITIAL ROUND OF THUNDERSTORMS LATE
SUNDAY MORNING INTO THE EARLY AFTERNOON. SOUTH OF THE AREA OF THE
MORNING THUNDERSTORMS THE BOUNDARY LAYER SHOULD BE ABLE TO
DESTABILIZE RAPIDLY THROUGHOUT THE DAY...SETTING THE STAGE FOR THE
MAIN PERIOD OF SEVERE THUNDERSTORMS.
MESOSCALE DETAILS WILL LIKELY NEED TO BE IRONED OUT THROUGHOUT THE
DAY TO DETERMINE THE TIMING AND STRENGTH OF THE STRONGEST STORMS FOR
THE AREA. 06Z RAP FORECAST OF SURFACE THETA E AND WIND DIRECTION
SHOWS A GOOD PUNCH OF DRY AIR COMING OFF THE SOUTHERN HIGH PLAINS
INTO THE WICHITA METRO AREA. THE EXACT LOCATION OF THIS DRY PUNCH
AND STRONG SURFACE WIND CONVERGENCE IS A LITTLE UNCERTAIN...BUT THAT
WOULD BE ONE OF THE FOCI FOR STORM DEVELOPMENT THIS AFTERNOON.
ANOTHER FACTOR IN FAVOR OF ROBUST CONVECTION ACROSS THE AREA IS THE
PRESENCE OF A VERY POTENT UPPER LEVEL JET...WHICH NOSES INTO SE
KANSAS...PUTTING THE CONVECTIVELY FAVORABLE LEFT EXIT REGION RIGHT
OVER THE FORECAST AREA. GIVEN THESE FACTORS IT APPEARS CONCEIVABLE
THAT A FEW STORMS WILL BE ABLE TO INITIATE 20-21Z IN THE
AFOREMENTIONED STRONG CONVERGENCE ZONE AND PUSH NORTHEAST UTILIZING
3500-4500 ML CAPE AND PERHAPS 40 TO 50 KTS OF DEEP LAYER SHEAR.
EXTREME MID LEVEL LAPSE RATES ON THE ORDER OF 9-9.5 C/KM WILL AID IN
CREATING THE EXTREME ML CAPE...SO ANY UPDRAFT THAT GOES UP DURING
PEAK HEATING WILL LIKELY BE ABLE TO PRODUCE LARGE HAIL...ON THE
ORDER OF BASEBALL SIZED...WITH PERHAPS SOME LARGER STONES. OF COURSE
WITH ANY STORM THAT BECOMES SURFACE BASED STRONG OUTFLOW WINDS WILL
ALWAYS BE PROBABLE...SO AREAS IN THE VICINITY OF THE STRONGEST
STORMS COULD SEE STRONG GUSTY WINDS ON THE ORDER OF 60 TO 70 MPH.
INITIAL STORM COVERAGE WILL LIKELY BE DICTATED BY DETAILED MESOSCALE
INFLUENCES AND COULD BE ISOLATED TO SCATTERED IN NATURE...HOWEVER
ONCE THE MAIN MID LEVEL SYSTEM CAN MOVE INTO THE AREA COVERAGE WILL
INCREASE...WITH DISCREET STORMS HAVING THE BEST CHANCE TO PRODUCE
LARGE HAIL...STRONG WINDS AND PERHAPS A TORNADO.
REGARDING THE TORNADO THREAT...GIVEN THE EXTREME INSTABILITY PRESENT
FOR THESE STORMS AND THE STRONG SHEAR IT CANNOT BE RULED OUT THAT A
TORNADO OR TWO COULD FORM. GIVEN THAT SURFACE WINDS WILL BE OUT OF
THE SSE AND LOW/MID LEVEL WINDS WILL BE VEERING WITH HEIGHT THE
GENERAL WIND SHEAR PROFILE WILL BE IN PLACE TO WARRANT A TORNADO
THREAT. FORECAST HODOGRAPHS FOR NUMEROUS STRONG TORNADOES ARE FAR
FROM PERFECT IN THIS SET UP...AS THE HODOGRAPHS LACK THE OPTIMAL
LOOPING CLOCKWISE STRUCTURE. WIND PROFILES DO LOOK A BIT BETTER WITH
THE LATEST RUNS OF THE MODELS THAN BEFORE...BUT STILL TAKE ON A BIT
OF AN S-SHAPE WITH COUNTERCLOCKWISE STRUCTURE. A PLANAR VIEW OF THE
LOW LEVEL WIND SHEAR SHOWS THAT ENOUGH TURNING WILL TAKE PLACE IN
THE LOWEST 1-3 KM TO CONTINUE A CONCERN FOR TORNADIC
BEHAVIOR...ESPECIALLY ONCE THE EARLY EVENING SETS IN AND THE LOW
LEVEL JET CAN INCREASE...LENGTHENING THE LOWEST LEVEL OF THE
HODOGRAPH. THE BOTTOM LINE IS THAT ALTHOUGH THE WIND SHEAR PROFILE
IS NOT PERFECT FOR STRONG TORNADOES TO OCCUR THERE IS ENOUGH OF A
SIGNAL FOR TORNADIC POTENTIAL TO WARRANT CONCERN FOR A DISCREET
STORM OR TWO TO PRODUCE A TORNADO...PERHAPS STRONG...ESPECIALLY IF A
BOUNDARY COMES INTO PLAY.
AS THE DAY WEARS ON STORM COVERAGE WILL LIKELY INCREASE AS THE MID
LEVEL TROUGH MOVES INTO THE AREA PROVIDING AMPLE ASCENT AND SUPPORT
FOR DEEP CONVECTION. ALSO MOVING THROUGH THE AREA IS A COLD FRONT
WHICH WILL ALSO AID IN INCREASING STORM COVERAGE AS IT PUSHES
THROUGH THE AREA. EXPECT A TRANSITION TO MCS/SQUALL LINE LATER IN
THE DAY AS STORMS INTERACT WITH EACH OTHER...EVENTUALLY CLEARING
THROUGH THE AREA OVERNIGHT SUNDAY NIGHT INTO MONDAY.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CDT SUN MAY 19 2013
MON-TUES...HAVE KEPT LINGERING OVERNIGHT POPS WEIGHTED TOWARD THE
EAST AS WILL HAVE TO SEE HOW EVENING CONVECTION UNFOLDS SUNDAY.
LEAD RIPPLE IN THE BIGGER LONGWAVE TROF APPEARS TO MOVE NE INTO
IOWA BY 12Z MONDAY AND WOULD EXPECT SOME CLEARING FROM WEST TO
EAST BY MORNING. BRUNT OF THE LONGWAVE TROF STILL POISED TO THE
WEST OF THE AREA HOWEVER...AND JET STREAK ROUNDS THE BASE OVER
EASTERN KS BY THE NOON HOUR MONDAY. THIS HELPS KEEP THE FRONT OVER
SOUTHEAST KANSAS. BY 06Z TUESDAY...THE RRE OF THE UPPER JET AND
BROAD LIFT FROM THE UPPER TROF MOVE OUT OVER THE FRONT ONCE
AGAIN...AND FIRES OFF MORE STORMS OVER SOUTHEAST KANSAS. THESE
STORMS WOULD BE SEVERE AS GOOD INSTABILITY AND SHEAR REMAIN IN
PLACE. THE BEST FOCUS FOR SEVERE LOOKS TO BE JUST SE OF THE
TOPEKA COUNTIES WITH A SLIGHT RISK ACROSS THE SOUTHEAST HALF. SOME
DETAIL DEPENDS ON MORE MESOSCALE MECHANISMS AND FORECAST LOCATION
MAY ADJUST SOMEWHAT BETWEEN NOW AND MONDAY...BUT FOR THOSE ALONG
AND SE OF I35 STAY TUNED FOR POSSIBLY MORE SEVERE WEATHER LATE
MONDAY. PRECIP CHANCES DIMINISH AFTER SUNRISE TUESDAY AND POPS
REFLECT THIS TREND. HIGHS BY TUESDAY ONLY ANTICIPATED TO BE IN THE
70S AS COOLER TEMPS FROM THE NW OVERTAKE THE CENTRAL PLAINS.
WED-SAT ANTICIPATE COOLER THAN NORMAL HIGH TEMPERATURES AS UPPER
TROF IS SLOW TO MOVE OFF TO THE EAST AND SURFACE HIGH PRESSURE
PUSHES INTO THE PLAINS BEHIND THE SYSTEM INTO THE END OF THE WEEK.
SW FLOW REESTABLISHES OVER THE SW STATES...AND FRONT IN BETWEEN
GENERATES SHOWERS AND THUNDER AT TIMES OVER THE SOUTHEAST COUNTIES.
WILL CARRY SOME POPS A BIT HIGHER TO THE SW AS A RESULT. GENERALLY
ANTICIPATE DAYTIME HIGHS IN THE 70S WITH OVERNIGHT LOWS IN THE
50S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 729 AM CDT SUN MAY 19 2013
EARLY MORNING SHOWERS SHOULD GIVE WAY TO A GRADUALLY CLEARING
SKY...ALTHOUGH THE STRATUS WILL BE TOUGH TO GET RID OF. EXPECT VFR
CONDITIONS DESPITE THE LIGHT RAIN THROUGH AT LEAST THIS AFTERNOON
BEFORE A ROUND OF SEVERE THUNDERSTORMS FORMS AROUND 20Z. EXPECT
THESE STORMS TO AFFECT THE TAF SITES THROUGH SUNSET BEFORE MOVING
EAST.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LEIGHTON
LONG TERM...CRAVEN
AVIATION...LEIGHTON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
446 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SUN MAY 19 2013
SHORT TERM FORECAST (SUNDAY AND SUNDAY NIGHT)...
THE POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EVENT REMAINS IN TACT
FOR SUNDAY ACROSS ALL OF EASTERN KANSAS...WITH ALL HAZARDS OF SEVERE
WEATHER POSSIBLE INCLUDING LARGE DAMAGING HAIL...STRONG WINDS...AND
PERHAPS A TORNADO OR TWO.
THE INITIAL SURFACE OBSERVATION MAP INDICATES A RATHER WORKED OVER
LOW LEVEL ATMOSPHERE IN THE WAKE OF STRONG STORMS WHICH HAVE SINCE
LEFT THE AREA. PREVIOUS AS WELL AS ONGOING CONVECTION WILL LIKELY
CREATE AN OUTFLOW BOUNDARY IN THE KS/OK BORDER REGION...WHICH MAY
PLAY A ROLE IN THUNDERSTORM DEVELOPMENT AND BEHAVIOR FOR SUNDAY.
CURRENTLY LIGHT RAIN ASSOCIATED WITH POST OFB OVER RUNNING REMAIN IN
THE AREA...MAINLY ACROSS SOUTHERN KANSAS. DEPENDING ON HOW MUCH
SKIES CAN CLEAR ON SUNDAY WILL HELP DETERMINE HOW MUCH THE
ATMOSPHERE WILL BE ABLE TO DESTABILIZE FOR SUNDAY AFTERNOON. WATER
VAPOR IMAGERY AS WELL AS RAP40 H5 ANALYSIS INDICATE THE STRONG MID
LEVEL TROUGH...PARTIALLY RESPONSIBLE FOR SATURDAYS
CONVECTION...REMAINS IN PLACE OVER THE HIGH PLAINS AS IT GRADUALLY
MOVES EAST. AS THE DAY PROGRESSES H5 HEIGHT FALLS WILL BE PREVALENT
ACROSS THE AREA. WITH A MOIST BOUNDARY LAYER IN PLACE...ALONG WITH A
POTENT MID LEVEL TROUGH MOVING THROUGH THE AREA...EXPECT A PERIOD OF
SEVERE WEATHER TO TAKE PLACE LATER TODAY ACROSS EASTERN KANSAS.
ALL HIGH RESOLUTION SHORT RANGE MODELS PROG A QUICK RECOVERY OF THE
BOUNDARY LAYER MOISTURE AHEAD OF A DEEPENING SURFACE LOW COMING OFF
THE SOUTHERN/CENTRAL HIGH PLAINS. STRONG SOUTHERLY SFC FLOW WILL AID
IN THE BOUNDARY LAYER MOISTURE RECOVERY THROUGH THE MORNING AND
EARLY AFTERNOON HOURS ON SUNDAY. AN INITIAL ROUND OF ELEVATED
THUNDERSTORMS WILL BE POSSIBLE LATE SUNDAY MORNING...MAINLY NORTH OF
INTERSTATE 70 AS WARM AIR ADVECTION RIDES OVER THE LOW LEVEL
INVERSION. AROUND 2000-3000 J/KG OF ELEVATED INSTABILITY WILL BE
PRESENT AS WELL AS AROUND 40 KTS OF DEEP LAYER SHEAR FOR ANY STORM
TO TAP INTO...SO ROBUST UPDRAFTS CAPABLE OF PRODUCING MAINLY LARGE
HAIL WILL BE POSSIBLE IN THIS INITIAL ROUND OF THUNDERSTORMS LATE
SUNDAY MORNING INTO THE EARLY AFTERNOON. SOUTH OF THE AREA OF THE
MORNING THUNDERSTORMS THE BOUNDARY LAYER SHOULD BE ABLE TO
DESTABILIZE RAPIDLY THROUGHOUT THE DAY...SETTING THE STAGE FOR THE
MAIN PERIOD OF SEVERE THUNDERSTORMS.
MESOSCALE DETAILS WILL LIKELY NEED TO BE IRONED OUT THROUGHOUT THE
DAY TO DETERMINE THE TIMING AND STRENGTH OF THE STRONGEST STORMS FOR
THE AREA. 06Z RAP FORECAST OF SURFACE THETA E AND WIND DIRECTION
SHOWS A GOOD PUNCH OF DRY AIR COMING OFF THE SOUTHERN HIGH PLAINS
INTO THE WICHITA METRO AREA. THE EXACT LOCATION OF THIS DRY PUNCH
AND STRONG SURFACE WIND CONVERGENCE IS A LITTLE UNCERTAIN...BUT THAT
WOULD BE ONE OF THE FOCI FOR STORM DEVELOPMENT THIS AFTERNOON.
ANOTHER FACTOR IN FAVOR OF ROBUST CONVECTION ACROSS THE AREA IS THE
PRESENCE OF A VERY POTENT UPPER LEVEL JET...WHICH NOSES INTO SE
KANSAS...PUTTING THE CONVECTIVELY FAVORABLE LEFT EXIT REGION RIGHT
OVER THE FORECAST AREA. GIVEN THESE FACTORS IT APPEARS CONCEIVABLE
THAT A FEW STORMS WILL BE ABLE TO INITIATE 20-21Z IN THE
AFOREMENTIONED STRONG CONVERGENCE ZONE AND PUSH NORTHEAST UTILIZING
3500-4500 ML CAPE AND PERHAPS 40 TO 50 KTS OF DEEP LAYER SHEAR.
EXTREME MID LEVEL LAPSE RATES ON THE ORDER OF 9-9.5 C/KM WILL AID IN
CREATING THE EXTREME ML CAPE...SO ANY UPDRAFT THAT GOES UP DURING
PEAK HEATING WILL LIKELY BE ABLE TO PRODUCE LARGE HAIL...ON THE
ORDER OF BASEBALL SIZED...WITH PERHAPS SOME LARGER STONES. OF COURSE
WITH ANY STORM THAT BECOMES SURFACE BASED STRONG OUTFLOW WINDS WILL
ALWAYS BE PROBABLE...SO AREAS IN THE VICINITY OF THE STRONGEST
STORMS COULD SEE STRONG GUSTY WINDS ON THE ORDER OF 60 TO 70 MPH.
INITIAL STORM COVERAGE WILL LIKELY BE DICTATED BY DETAILED MESOSCALE
INFLUENCES AND COULD BE ISOLATED TO SCATTERED IN NATURE...HOWEVER
ONCE THE MAIN MID LEVEL SYSTEM CAN MOVE INTO THE AREA COVERAGE WILL
INCREASE...WITH DISCREET STORMS HAVING THE BEST CHANCE TO PRODUCE
LARGE HAIL...STRONG WINDS AND PERHAPS A TORNADO.
REGARDING THE TORNADO THREAT...GIVEN THE EXTREME INSTABILITY PRESENT
FOR THESE STORMS AND THE STRONG SHEAR IT CANNOT BE RULED OUT THAT A
TORNADO OR TWO COULD FORM. GIVEN THAT SURFACE WINDS WILL BE OUT OF
THE SSE AND LOW/MID LEVEL WINDS WILL BE VEERING WITH HEIGHT THE
GENERAL WIND SHEAR PROFILE WILL BE IN PLACE TO WARRANT A TORNADO
THREAT. FORECAST HODOGRAPHS FOR NUMEROUS STRONG TORNADOES ARE FAR
FROM PERFECT IN THIS SET UP...AS THE HODOGRAPHS LACK THE OPTIMAL
LOOPING CLOCKWISE STRUCTURE. WIND PROFILES DO LOOK A BIT BETTER WITH
THE LATEST RUNS OF THE MODELS THAN BEFORE...BUT STILL TAKE ON A BIT
OF AN S-SHAPE WITH COUNTERCLOCKWISE STRUCTURE. A PLANAR VIEW OF THE
LOW LEVEL WIND SHEAR SHOWS THAT ENOUGH TURNING WILL TAKE PLACE IN
THE LOWEST 1-3 KM TO CONTINUE A CONCERN FOR TORNADIC
BEHAVIOR...ESPECIALLY ONCE THE EARLY EVENING SETS IN AND THE LOW
LEVEL JET CAN INCREASE...LENGTHENING THE LOWEST LEVEL OF THE
HODOGRAPH. THE BOTTOM LINE IS THAT ALTHOUGH THE WIND SHEAR PROFILE
IS NOT PERFECT FOR STRONG TORNADOES TO OCCUR THERE IS ENOUGH OF A
SIGNAL FOR TORNADIC POTENTIAL TO WARRANT CONCERN FOR A DISCREET
STORM OR TWO TO PRODUCE A TORNADO...PERHAPS STRONG...ESPECIALLY IF A
BOUNDARY COMES INTO PLAY.
AS THE DAY WEARS ON STORM COVERAGE WILL LIKELY INCREASE AS THE MID
LEVEL TROUGH MOVES INTO THE AREA PROVIDING AMPLE ASCENT AND SUPPORT
FOR DEEP CONVECTION. ALSO MOVING THROUGH THE AREA IS A COLD FRONT
WHICH WILL ALSO AID IN INCREASING STORM COVERAGE AS IT PUSHES
THROUGH THE AREA. EXPECT A TRANSITION TO MCS/SQUALL LINE LATER IN
THE DAY AS STORMS INTERACT WITH EACH OTHER...EVENTUALLY CLEARING
THROUGH THE AREA OVERNIGHT SUNDAY NIGHT INTO MONDAY.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CDT SUN MAY 19 2013
MON-TUES...HAVE KEPT LINGERING OVERNIGHT POPS WEIGHTED TOWARD THE
EAST AS WILL HAVE TO SEE HOW EVENING CONVECTION UNFOLDS SUNDAY.
LEAD RIPPLE IN THE BIGGER LONGWAVE TROF APPEARS TO MOVE NE INTO
IOWA BY 12Z MONDAY AND WOULD EXPECT SOME CLEARING FROM WEST TO
EAST BY MORNING. BRUNT OF THE LONGWAVE TROF STILL POISED TO THE
WEST OF THE AREA HOWEVER...AND JET STREAK ROUNDS THE BASE OVER
EASTERN KS BY THE NOON HOUR MONDAY. THIS HELPS KEEP THE FRONT OVER
SOUTHEAST KANSAS. BY 06Z TUESDAY...THE RRE OF THE UPPER JET AND
BROAD LIFT FROM THE UPPER TROF MOVE OUT OVER THE FRONT ONCE
AGAIN...AND FIRES OFF MORE STORMS OVER SOUTHEAST KANSAS. THESE
STORMS WOULD BE SEVERE AS GOOD INSTABILITY AND SHEAR REMAIN IN
PLACE. THE BEST FOCUS FOR SEVERE LOOKS TO BE JUST SE OF THE
TOPEKA COUNTIES WITH A SLIGHT RISK ACROSS THE SOUTHEAST HALF. SOME
DETAIL DEPENDS ON MORE MESOSCALE MECHANISMS AND FORECAST LOCATION
MAY ADJUST SOMEWHAT BETWEEN NOW AND MONDAY...BUT FOR THOSE ALONG
AND SE OF I35 STAY TUNED FOR POSSIBLY MORE SEVERE WEATHER LATE
MONDAY. PRECIP CHANCES DIMINISH AFTER SUNRISE TUESDAY AND POPS
REFLECT THIS TREND. HIGHS BY TUESDAY ONLY ANTICIPATED TO BE IN THE
70S AS COOLER TEMPS FROM THE NW OVERTAKE THE CENTRAL PLAINS.
WED-SAT ANTICIPATE COOLER THAN NORMAL HIGH TEMPERATURES AS UPPER
TROF IS SLOW TO MOVE OFF TO THE EAST AND SURFACE HIGH PRESSURE
PUSHES INTO THE PLAINS BEHIND THE SYSTEM INTO THE END OF THE WEEK.
SW FLOW REESTABLISHES OVER THE SW STATES...AND FRONT IN BETWEEN
GENERATES SHOWERS AND THUNDER AT TIMES OVER THE SOUTHEAST COUNTIES.
WILL CARRY SOME POPS A BIT HIGHER TO THE SW AS A RESULT. GENERALLY
ANTICIPATE DAYTIME HIGHS IN THE 70S WITH OVERNIGHT LOWS IN THE
50S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1225 AM CDT SUN MAY 19 2013
WILL HANG ONTO A MENTION OF PRECIP WITH CONDITIONS GENERALLY VFR
AS HI-RES MODELS SHOW CONVECTION IN NORTHWEST OK MOVING ACROSS
NORTHEAST KS. OTHERWISE CONFIDENCE IN FORECAST DETAILS BEYOND THE
NEXT SEVERAL HOURS IS LOW. STILL EXPECT CONVECTION TO DEVELOP
SUNDAY AFTERNOON...BUT DETAILS WILL NEED TO BE FINE TUNED.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LEIGHTON
LONG TERM...CRAVEN
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS JACKSON KY
310 PM EDT SUN MAY 19 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 310 PM EDT SUN MAY 19 2013
MID/UPPER LOW OVER NORTHEAST KY WILL CONTINUE TO PULL AWAY WITH UPPER
RIDGING BUILDING INTO THE AREA FOR MONDAY. AN UPPER LEVEL LOCAL SPEED
MAXIMUM ON THE SOUTHERN SIDE OF THE LOW HAS HELPED SUPPORT THE
DEVELOPMENT OF NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE
SOUTHERN PART OF THE FORECAST AREA TODAY. SPEED MAX IS FORECAST TO WEAKEN
AND MOVE AWAY FROM THE AREA. THIS COMBINED WITH LOSS OF DAYTIME
HEATING SHOULD RESULT IN A QUICK DECREASE IN CONVECTION THIS EVENING.
THIS IS SUPPORTED BY THE 12Z NAM AND LATEST HRRR. THE HRRR DOES HAVE
SOME CONVECTION LINGERING TO AT LEAST MIDNIGHT...AND WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE SOUTHEAST THROUGH
THIS TIME. FOG WILL DEVELOP AGAIN TONIGHT...WITH LOCALLY DENSE FOG
ESPECIALLY IN AREAS WHERE RAIN FELL TODAY.
WITH UPPER RIDGING OVER THE AREA ON MONDAY EXPECT CONVECTION TO BE
LESS ORGANIZED...EVEN THOUGH LOW LEVEL LAPSE RATES AND SURFACE BASED
INSTABILITY WILL BE GREATER THAN TODAY. WHILE THERE WILL NOT BE ANY
UPPER FORCING LIKE TODAY THERE WILL BE NUMEROUS BOUNDARIES LEFT FROM
TODAYS CONVECTION...SO WILL GO WITH SLIGHT CHANCE TO CHANCE
PROBABILITIES OVER ALL BUT THE FAR WESTERN TIER OF COUNTIES FOR
MONDAY. EXPECT ANY CONVECTION ON MONDAY TO AGAIN QUICKLY DISSIPATE
DURING THE EVENING.
WITH SHORT RANGE SOIL MOISTURE AND DROUGHT INDICES
SHOWING WETTER THAN NORMAL CONDITIONS IN THE FORECAST AREA WILL
CONTINUE TO DISREGARD THE GFS MOS HIGH TEMPERATURES OF 90 DEGREES FOR
MONDAY. WILL GO MOSTLY WITH MIDDLE 80S. RECORD HIGHS FOR MONDAY ARE
85 IN 1987 AT JKL AND 88 IN 1962 AT LOZ. WILL ALSO LEAN TOWARDS THE
NAM MOS PROBABILITY OF RAIN CHANCE GUIDANCE WHICH KEEPS LOW CHANCES
FOR TONIGHT AND MONDAY NIGHT...WITH BEST CHANCE FOR MONDAY. THIS IS
THE COMPLETE OPPOSITE OF THE GFS MOS GUIDANCE WHICH PLACES LOW
PROBABILITIES ON MONDAY WITH THE BEST CHANCES TONIGHT AND MONDAY
NIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 310 PM EDT SUN MAY 19 2013
THE EXTENDED FORECAST BEGINS WITH A RIDGE OVER THE EAST COAST AND A
SERIES OF MID LEVEL DISTURBANCES PRESSING EAST ALONG THE NRN CONUS
BORDER. A WAVE IN THE ERN PLAINS HAS SOUTHERLY FLOW AT THE SFC
WHICH WILL BRING GULF MOISTURE INTO ERN KY. SCATTERED TO NUMEROUS
SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR WITHOUT MUCH ORGANIZATION
AS THE SFC LOW TAKES FORM AND MOVES INTO THE WRN GREAT LAKES. BY WED
THE COLD FRONT WILL MOVE INTO WRN KY AS THE MID LEVEL OPENS INTO A
WAVE AS IT PUSHES OVER THE ERN RIDGE. WED NIGHT WILL SEE A SERIES OF
WAVES CYCLE AROUND THE SRN EDGE OF THE 50H DISTURBANCE WITH
SCATTERED AREAS OF PCPN REFLECTED AT THE SFC. BY EARLY FRI MORNING
THE UPPER PATTERN HAS CHANGED TO A PLAINS RIDGE AND COASTAL TROFS.
SFC HIGH PRESSURE WILL DROP FROM THE NRN PLAINS AND BRING A PERIOD
OF DRY WEATHER. THAT WILL LAST THRU THE WEEKEND AS THE SFC HIGH
DRIFTS TOWARD THE EAST COAST WITH THE UPPER PATTERN BECOMING MORE
PROGRESSIVE.
FOR SENSIBLE WEATHER THE SOUTHERLY FLOW FROM THE GULF ON TUE WILL
BRING SCATTERED PCPN ALONG WITH TEMPS INTO THE MID 80S. THIS PATTERN
WILL CONTINUE THRU WED WITH OVERNIGHT LOWS RESTRICTED TO THE MID 60S
DUE TO HIGH DWPTS AND CLOUDS. THEN ON THU THE FIRST COLD FRONT WILL
CROSS ERN KY WITH SCATTERED STORMS AND COOLER TEMPS AS HIGHS ONLY
REACH THE UPPER 70S AND LOWS THU NIGHT DROP TO AROUND 60. WITH THE
SECOND SURGE OF COLD AIR FOLLOWING ON FRI LOOK FOR HIGHS IN THE MID
70S AND CLEARING LATE FRI WILL ALLOW OVERNIGHT LOWS TO DROP TO THE
MID 50S. THE COOL AIR WILL KEEP SAT HIGHS IN THE LOWER 70S IN SPITE
OF A REDUCTION IN CLOUDS EARLY AS THE DAYTIME MIXING WILL HELP
INCREASE CLOUD COVER TO COMPLEMENT THE COOLER NORTH WINDS. AS THE
DRIER AIR MOVES INTO ERN KY ON SUN THE WINDS WILL DIMINISH WITH THE
HIGH PRESSURE CROSSING TO OUR NORTH AND THE SUN WILL BEGIN THE
HEATING TO PUSH HIGHS BACK INTO THE MID 70S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 138 PM EDT SUN MAY 19 2013
UPPER LEVEL LOW PRESSURE OVER NE KY IS BRINGING SCATTERED SHOWERS AND
THUNDERSTORMS TO THE FORECAST AREA...WITH THE THUNDERSTORMS MOST
NUMEROUS OVER SOUTHERN PARTS OF THE FORECAST AREA. AT TAF ISSUANCE
TIME SHOWERS AND THUNDERSTORMS ARE ABOUT TO END AT LOZ AND SME...BUT
MVFR FOG AND CEILINGS WILL PERSIST UNTIL 19Z AT THESE LOCATIONS.
THUNDERSTORMS ARE MORE ISOLATED FURTHER NORTH...WITH MAINLY ISOLATED
SHOWERS FROM JKL NORTH. OUTSIDE OF SHOWERS AND THUNDERSTORMS VFR
CONDITIONS WILL PREVAIL INTO THE EVENING HOURS. FOG AND LOW CLOUD IS
EXPECTED TO DEVELOP TONIGHT...ESPECIALLY IN AREAS THAT RECEIVED RAIN
TODAY. EXPECT IFR TO LOW IFR CONDITIONS BY EARLY MONDAY
MORNING...IMPROVING TO VFR BY MONDAY AFTERNOON.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SBH
LONG TERM...DUSTY
AVIATION...SBH
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
144 PM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK FRONT OVER SOUTHERN VIRGINIA AND LIFTING SLOWLY NORTH AND WILL
DISSIPATE ACROSS MARYLAND ON MONDAY. A RIDGE OF HIGH PRESSURE OFF
THE SOUTHEAST COAST WILL DOMINATE INTO THE MIDDLE OF THE WEEK. A
COLD FRONT WILL PASS THROUGH THE MID ATLANTIC STATES AROUND
FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1 PM UPDATE...INCREASED POPS TOWARD THE COAST OVER SE VA AND NE NC
WHERE WIDESPREAD SHOWERS ARE DEVELOPING IN AREAS THAT RECEIVED
SUNSHINE THIS MORNING.
10AM UPDATE...MADE SMALL CHANGES TO THE FORECAST AND BUMPED POPS
UP SLIGHTLY OVER SOUTHEAST PORTIONS SO THAT THE ENTIRE CWA HAS
LIKELY SHOWERS. MOST OF THE AREA WILL REMAIN MOSTLY CLOUDY TO
CLOUDY BUT SIGNIFICANT BREAKS SHOULD CONTINUE TO APPEAR OVER SE VA
AND NE NC WHICH WILL PROMOTE SHOWER DEVELOPMENT IN THE AFTN. MAX
TEMPERATURE FORECAST REMAINS MOSTLY IN THE MID TO UPR 70S WITH NEAR
80 DEGREES EXPECTED OVER INTERIOR SOUTHEAST VIRGINIA. LOWEST
READINGS WILL BE IN NORTHERN PORTIONS AND ALONG THE COAST. CONTINUED
WITH ISOLATED THUNDER EXCEPT IN PORTIONS OF THE MD EASTERN SHORE.
WENT WITH ISOLATED DUE TO CONVERGENCE AND CAPE BEING WEAKER THAN THEY
WERE SATURDAY.
PREVIOUS DISCUSSION...
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW STUBBORN
UPPER LOW OVER WRN KY WITH A RATHER BROAD MID/UPPER LEVEL TROUGH
SITUATED FROM KY DOWN INTO THE CAROLINAS. AT THE SFC...STATIONARY
FRONT/BOUNDARY STILL LOCATED OVER NRN NC. AREA OF SHOWERS AND
EMBEDDED THUNDERSTORMS DEVELOPED ALONG THE BOUNDARY IN N CNTRL NC
EARLIER THIS MORNING...BUT HAVE SINCE WEAKENED AS THEY MOVED NORTH
INTO THE REGION. CLOUD TOPS HAVE WARMED...BUT A FEW SHALLOW
SHOWERS ONGOING OVER THE ERN SHORE...AIDED BY MID LEVEL
ENERGY/SHORTWAVE. RUC H7 OMEGA HANDLES THIS AREA OF SHOWERS
WELL...WITH THE SHOWERS PUSHING OFFSHORE IN THE NEXT FEW HOURS. IN
ADDITION...VERY MOIST BOUNDARY LAYER...WAA AND CALM WINDS HAVE
RESULTED IN AREAS OF FOG THIS MORNING...WITH SOME VISIBILITIES AS
LOW AS HALF A MILE IN THE RICHMOND AREA.
ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE DYING UPPER LOW
INTO A WARM/MOIST AIRMASS...WITH THE FIRST ARRIVING LATER THIS
MORNING. COOLING CLOUD TOPS ALREADY OBSERVED THIS MORNING OVER WRN
NC. PRECIP WATERS STILL AROUND 1.5 INCHES (+1 STD DEV). EXPECT
SHOWERS TO INCREASE IN COVERAGE ACROSS THE ERN VA PIEDMONT BY MID
MORNING. FOR THIS AFTERNOON...WEAKENING UPPER LOW WILL REMAIN IN
THE VICINITY OF WRN KY AS THE BOUNDARY BEGINS TO LIFT NWD AS A
WARM FRONT. SHORTWAVE WILL LIFT THROUGH VA...COMBINING WITH WEAK
DIVERGENCE ALOFT TO PROVIDE FORCING FOR ASCENT...ALBEIT WEAK.
HOWEVER...WITH ABUNDANT MOISTURE IN PLACE...IT WILL BE ENOUGH TO
TRIGGER ADDITIONAL SHOWERS THIS AFTERNOON...MAINLY ACROSS THE
PIEDMONT INTO CNTRL VA. INSTABILITY WILL BE LIMITED...BUT GOOD LOW
LEVEL LAPSE RATES AND THETA-E ADVECTION WILL BE ENOUGH FOR
SCATTERED AFTERNOON THUNDERSTORMS....MAINLY ACROSS SRN VA. S/SE
FLOW WILL LIMIT THE AMOUNT OF INSTABILITY ALONG THE COAST AND OVER
THE ERN SHORE. MID LEVEL WIND FIELDS ARE RATHER WEAK...SO THE
MAIN THREAT FROM THUNDERSTORMS WILL BE HEAVY RAIN.
ANOTHER CLOUDY/WET DAY WILL PREVENT TEMPS FROM REACHING THEIR FULL
POTENTIAL...WITH HIGHS GENERALLY IN THE MID/UPPER 70S. COLDER
ALONG THE IMMEDIATE COAST AND OVER THE ERN SHORE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
REMNANTS OF THE UPPER LOW WILL EJECT OVER THE APPALACHIANS SUNDAY
NIGHT INTO MONDAY AS A POTENT UPPER TROUGH REACHES THE MIDWEST. AT
THE SFC...WARM FRONT WILL LOCATE NORTH OF THE FA MONDAY AFTERNOON
AS HIGH PRESSURE LOCATED OVER THE WRN ATLANTIC EXTENDS WWD INTO
THE LOWER MID ATLANTIC AND SE STATES. WARM/MOIST AIRMASS WILL
BUILD IN AS S/SW FLOW ADVECTS DEEP MOIST FROM THE ATLANTIC...WITH
PRECIP WATER VALUES APPROACHING +1.5 STD DEV. WEAK SHORTWAVE AND
DIVERGENCE ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT...BUT
EXPECT MOST FORCING AND RESULTANT CONVECTION TO BE DIURNALLY
DRIVEN. WHILE THETA-E ADVECTION AND WARM TEMPERATURES WILL PROVIDE
MARGINAL INSTABILITY (500-1000 J/KG CAPE)...A WEAKENING MID LEVEL
WIND FIELD WILL PROVIDE LIMITED SHEAR. THE RESULT WILL BE
SCATTERED THUNDERSTORMS WITH VERY LITTLE ORGANIZATION. THE
SHORTWAVE AXIS PROGGED TO BE AROUND THE ERN VA PIEDMONT...WITH THE
BEST CHANCES FOR SHOWERS/THUNDERSTORMS BEING TO THE EAST OF THE
AXIS OVER CNTRL AND ERN VA.
TROUGH AXIS WILL LOCATE ALONG THE COAST TUESDAY AS THE CNTRL CONUS
TROUGH AMPLIFIES THE UPPER RIDGE OVER THE EAST. RESIDUAL MOISTURE
AND SUBTLE UVM WILL BE SUFFICIENT FOR SHOWERS ALONG THE COAST
TUESDAY AFTERNOON. DEWPOINTS IN THE MID 60S AND AFTERNOON TEMPS IN
THE LOW/MID 80S WILL RESULT IN GREATER INSTABILITY (~1500 J/KG
CAPE AND ~-6 LIFTED INDEX) FOR CONVECTION/THUNDERSTORMS. FORCING
WILL BE MOSTLY DIURNALLY DRIVEN. HOWEVER...SHEAR REMAINS WEAK SO
EXPECT NO ORGANIZED THUNDERSTORMS.
NEAR SEASONABLE NORMAL TEMPS MONDAY (UPPER 70S/LOW 80S) BEFORE A
WARMING TREND TUESDAY. INCREASING HEIGHTS/THICKNESSES...AS WELL AS
850 TEMPS APPROACHING +1 STD DEV...WILL RESULT IN TEMPS GENERALLY
IN THE MID 80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODELS SIMILAR OVER THIS TIME PERIOD WITH THE TIMING OF ANOTHER TROF
DEEPING AT 500 MB TOWARD FRIDAY AND SATURDAY. THIS WILL USHER A
STRONGER COLD FRONT THROUGH THE REGION FRIDAY INTO SATURDAY. THE
FRONT WILL HAVE SOME SHOWERS AND THUNDERSTORMS WITH IT AS IT MOVES
THROUGH. BEFORE THAT A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY
ACROSS THE GREAT LAKES AND NEW ENGLAND. SOUTH OF THIS AREA WILL HAVE
GENERAL SOUTH TO SOUTHWEST FLOW ACROSS THE AREA. COULD SEE AN
ISOLATED AFTERNOON THUNDERSTORM. ANY THUNDERSTORMS THAT FORM NORTH
ALONG THE BOUNDARY COULD PUSH INTO THE NORTHERN PART OF THE AREA
DURING THE EVENINGS. TEMPERATURES WILL BE AT OR ABOVE NORMAL UNTIL
THE FRONT PASSES. THEN TEMPERATURES WILL DROP BACK ON SATURDAY TO AT
OR BELOW NORMAL.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
A MIX OF VFR AND MVFR CONDITIONS ACROSS THE REGION THIS AFTERNOON
WITH SHOWERS DEVELOPING FROM ECG TO ORF AND SOUTH OF RIC. EXPECT
MAINLY MVFR CONDITIONS AT RIC INTO THIS EVENING WITH A FEW SHOWERS
MOVING THROUGH AFTER 19Z. AT ORF CONDITIONS SHOULD REMAIN VFR
UNTIL HEAVIER SHOWERS REACH THE AIRPORT AROUND 19Z REDUCING VSBY
TO MVFR AND PERHAPS EVEN TEMPORARILY IFR. NELY FLOW AT ORF IS DUE
TO A WEAK BAY BREEZE AND WILL BECOME SLY THIS EVENING. JUST TO THE
NORTH PHF HAS BEEN SLOW TO IMPROVE AND WILL REMAIN MVFR FOR THE
AFTERNOON AND EVENING. SBY HAS CONTINUE TO SEE IFR CONDITIONS BUT
THIS WILL TEMPORARILY IMPROVE TO MVFR BY THIS EVENING BEFORE
RETURNING TO IFR OVERNIGHT.
SHOWERS WILL DISSIPATE WITH LOSS OF HEATING OVERNIGHT OUTSIDE OF A
FEW STRAY SHOWERS HERE AND THERE. DESPITE MOST OF THE GUIDANCE
KEEPING CONDITIONS ABOVE IFR DUE TO THE LOW LEVEL MOISTURE AND
CONTINUES BOUNDARY ACROSS THE REGION EXPECT IFR CEILINGS AND FOG TO
RE-DEVELOP OVERNIGHT AT ALL TAF SITES. THESE IFR CONDITIONS WILL
LINGER INTO MONDAY MORNING IMPROVING SLOWLY THROUGH MID MORNING.
MORE WIDESPREAD SHOWERS ARE EXPECTED MONDAY AFTERNOON AND EVENING
WITH MORE COVERAGE OF HEAVY SHOWERS THAN COMPARED TO SUNDAY.
&&
.MARINE...
S/SE WINDS PREVAIL ACROSS THE MARINE AREA THIS MORNING...WITH
SPEEDS BELOW SCA CRITERIA EVERYWHERE EVEN INTO THE AFTERNOON. WINDS
GENERALLY 10 KT THROUGH LATE MORNING INCREASING TO 10-15KT ON THE
BAY/RIVERS/SOUND...AND 10-20 KT ON THE OCEAN /HIGHEST N OF CAPE
CHARLES LIGHT/. THESE CONDITIONS EXPECTED TO PERSIST NEXT 2-3
DAYS...BEFORE WINDS BECOME SSWLY/SWLY IN THE TUE TIME FRAME.
SEAS ON THE COASTAL WATERS CONTINUE TO RUN AROUND 4-5 FEET AND
HAVE BEEN SLOWLY DECREASING OVER THE LAST FEW HOURS. WIND FORECASTS
DO NOT APPEAR TO BE SUFFICIENT TO CAUSE SEAS TO INCREASE TO 5+
FEET. HOWEVER...WAVEWATCH GUIDANCE PERSISTS IN PLACING MOST OF THE
COASTAL WATERS IN 5-6 FOOT SEAS TODAY/TONIGHT. WILL MAINTAIN SCA
FOR THE NRN 2 CSTL ZONES FOR SEAS THROUGH 00Z MON AS WINDS MAY
TEMPORARILY INCREASE THIS AFTERNOON PUSHING SEAS IN THE NORTH OF
NEAR 5 FT. SEAS EXPECTED TO SUBSIDE BELOW 5 FEET AFTER 00Z MON.
&&
.HYDROLOGY...
RIVER LEVEL FORECASTS HAVE BEEN LOWERED SUBSTANTIALLY DUE TO LACK
OF SIGNIFICANT RAINFALL IN THE HEADWATERS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ650.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ652.
&&
$$
SYNOPSIS...LKB/LSA
NEAR TERM...SAM/LSA
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...JAO
MARINE...WRS
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1246 PM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK FRONT OVER SOUTHERN VIRGINIA AND LIFTING SLOWLY NORTH AND WILL
DISSIPATE ACROSS MARYLAND ON MONDAY. A RIDGE OF HIGH PRESSURE OFF
THE SOUTHEAST COAST WILL DOMINATE INTO THE MIDDLE OF THE WEEK. A
COLD FRONT WILL PASS THROUGH THE MID ATLANTIC STATES AROUND
FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1 PM UPDATE...INCREASED POPS TOWARD THE COAST OVER SE VA AND NE NC
WHERE WIDESPREAD SHOWERS ARE DEVELOPING IN AREAS THAT RECEIVED
SUNSHINE THIS MORNING.
10AM UPDATE...MADE SMALL CHANGES TO THE FORECAST AND BUMPED POPS
UP SLIGHTLY OVER SOUTHEAST PORTIONS SO THAT THE ENTIRE CWA HAS
LIKELY SHOWERS. MOST OF THE AREA WILL REMAIN MOSTLY CLOUDY TO
CLOUDY BUT SIGNIFICANT BREAKS SHOULD CONTINUE TO APPEAR OVER SE VA
AND NE NC WHICH WILL PROMOTE SHOWER DEVELOPMENT IN THE AFTN. MAX
TEMPERATURE FORECAST REMAINS MOSTLY IN THE MID TO UPR 70S WITH NEAR
80 DEGREES EXPECTED OVER INTERIOR SOUTHEAST VIRGINIA. LOWEST
READINGS WILL BE IN NORTHERN PORTIONS AND ALONG THE COAST. CONTINUED
WITH ISOLATED THUNDER EXCEPT IN PORTIONS OF THE MD EASTERN SHORE.
WENT WITH ISOLATED DUE TO CONVERGENCE AND CAPE BEING WEAKER THAN THEY
WERE SATURDAY.
PREVIOUS DISCUSSION...
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW STUBBORN
UPPER LOW OVER WRN KY WITH A RATHER BROAD MID/UPPER LEVEL TROUGH
SITUATED FROM KY DOWN INTO THE CAROLINAS. AT THE SFC...STATIONARY
FRONT/BOUNDARY STILL LOCATED OVER NRN NC. AREA OF SHOWERS AND
EMBEDDED THUNDERSTORMS DEVELOPED ALONG THE BOUNDARY IN N CNTRL NC
EARLIER THIS MORNING...BUT HAVE SINCE WEAKENED AS THEY MOVED NORTH
INTO THE REGION. CLOUD TOPS HAVE WARMED...BUT A FEW SHALLOW
SHOWERS ONGOING OVER THE ERN SHORE...AIDED BY MID LEVEL
ENERGY/SHORTWAVE. RUC H7 OMEGA HANDLES THIS AREA OF SHOWERS
WELL...WITH THE SHOWERS PUSHING OFFSHORE IN THE NEXT FEW HOURS. IN
ADDITION...VERY MOIST BOUNDARY LAYER...WAA AND CALM WINDS HAVE
RESULTED IN AREAS OF FOG THIS MORNING...WITH SOME VISIBILITIES AS
LOW AS HALF A MILE IN THE RICHMOND AREA.
ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE DYING UPPER LOW
INTO A WARM/MOIST AIRMASS...WITH THE FIRST ARRIVING LATER THIS
MORNING. COOLING CLOUD TOPS ALREADY OBSERVED THIS MORNING OVER WRN
NC. PRECIP WATERS STILL AROUND 1.5 INCHES (+1 STD DEV). EXPECT
SHOWERS TO INCREASE IN COVERAGE ACROSS THE ERN VA PIEDMONT BY MID
MORNING. FOR THIS AFTERNOON...WEAKENING UPPER LOW WILL REMAIN IN
THE VICINITY OF WRN KY AS THE BOUNDARY BEGINS TO LIFT NWD AS A
WARM FRONT. SHORTWAVE WILL LIFT THROUGH VA...COMBINING WITH WEAK
DIVERGENCE ALOFT TO PROVIDE FORCING FOR ASCENT...ALBEIT WEAK.
HOWEVER...WITH ABUNDANT MOISTURE IN PLACE...IT WILL BE ENOUGH TO
TRIGGER ADDITIONAL SHOWERS THIS AFTERNOON...MAINLY ACROSS THE
PIEDMONT INTO CNTRL VA. INSTABILITY WILL BE LIMITED...BUT GOOD LOW
LEVEL LAPSE RATES AND THETA-E ADVECTION WILL BE ENOUGH FOR
SCATTERED AFTERNOON THUNDERSTORMS....MAINLY ACROSS SRN VA. S/SE
FLOW WILL LIMIT THE AMOUNT OF INSTABILITY ALONG THE COAST AND OVER
THE ERN SHORE. MID LEVEL WIND FIELDS ARE RATHER WEAK...SO THE
MAIN THREAT FROM THUNDERSTORMS WILL BE HEAVY RAIN.
ANOTHER CLOUDY/WET DAY WILL PREVENT TEMPS FROM REACHING THEIR FULL
POTENTIAL...WITH HIGHS GENERALLY IN THE MID/UPPER 70S. COLDER
ALONG THE IMMEDIATE COAST AND OVER THE ERN SHORE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
REMNANTS OF THE UPPER LOW WILL EJECT OVER THE APPALACHIANS SUNDAY
NIGHT INTO MONDAY AS A POTENT UPPER TROUGH REACHES THE MIDWEST. AT
THE SFC...WARM FRONT WILL LOCATE NORTH OF THE FA MONDAY AFTERNOON
AS HIGH PRESSURE LOCATED OVER THE WRN ATLANTIC EXTENDS WWD INTO
THE LOWER MID ATLANTIC AND SE STATES. WARM/MOIST AIRMASS WILL
BUILD IN AS S/SW FLOW ADVECTS DEEP MOIST FROM THE ATLANTIC...WITH
PRECIP WATER VALUES APPROACHING +1.5 STD DEV. WEAK SHORTWAVE AND
DIVERGENCE ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT...BUT
EXPECT MOST FORCING AND RESULTANT CONVECTION TO BE DIURNALLY
DRIVEN. WHILE THETA-E ADVECTION AND WARM TEMPERATURES WILL PROVIDE
MARGINAL INSTABILITY (500-1000 J/KG CAPE)...A WEAKENING MID LEVEL
WIND FIELD WILL PROVIDE LIMITED SHEAR. THE RESULT WILL BE
SCATTERED THUNDERSTORMS WITH VERY LITTLE ORGANIZATION. THE
SHORTWAVE AXIS PROGGED TO BE AROUND THE ERN VA PIEDMONT...WITH THE
BEST CHANCES FOR SHOWERS/THUNDERSTORMS BEING TO THE EAST OF THE
AXIS OVER CNTRL AND ERN VA.
TROUGH AXIS WILL LOCATE ALONG THE COAST TUESDAY AS THE CNTRL CONUS
TROUGH AMPLIFIES THE UPPER RIDGE OVER THE EAST. RESIDUAL MOISTURE
AND SUBTLE UVM WILL BE SUFFICIENT FOR SHOWERS ALONG THE COAST
TUESDAY AFTERNOON. DEWPOINTS IN THE MID 60S AND AFTERNOON TEMPS IN
THE LOW/MID 80S WILL RESULT IN GREATER INSTABILITY (~1500 J/KG
CAPE AND ~-6 LIFTED INDEX) FOR CONVECTION/THUNDERSTORMS. FORCING
WILL BE MOSTLY DIURNALLY DRIVEN. HOWEVER...SHEAR REMAINS WEAK SO
EXPECT NO ORGANIZED THUNDERSTORMS.
NEAR SEASONABLE NORMAL TEMPS MONDAY (UPPER 70S/LOW 80S) BEFORE A
WARMING TREND TUESDAY. INCREASING HEIGHTS/THICKNESSES...AS WELL AS
850 TEMPS APPROACHING +1 STD DEV...WILL RESULT IN TEMPS GENERALLY
IN THE MID 80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODELS SIMILAR OVER THIS TIME PERIOD WITH THE TIMING OF ANOTHER TROF
DEEPING AT 500 MB TOWARD FRIDAY AND SATURDAY. THIS WILL USHER A
STRONGER COLD FRONT THROUGH THE REGION FRIDAY INTO SATURDAY. THE
FRONT WILL HAVE SOME SHOWERS AND THUNDERSTORMS WITH IT AS IT MOVES
THROUGH. BEFORE THAT A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY
ACROSS THE GREAT LAKES AND NEW ENGLAND. SOUTH OF THIS AREA WILL HAVE
GENERAL SOUTH TO SOUTHWEST FLOW ACROSS THE AREA. COULD SEE AN
ISOLATED AFTERNOON THUNDERSTORM. ANY THUNDERSTORMS THAT FORM NORTH
ALONG THE BOUNDARY COULD PUSH INTO THE NORTHERN PART OF THE AREA
DURING THE EVENINGS. TEMPERATURES WILL BE AT OR ABOVE NORMAL UNTIL
THE FRONT PASSES. THEN TEMPERATURES WILL DROP BACK ON SATURDAY TO AT
OR BELOW NORMAL.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
A MIX OF VFR TO IFR CONDITIONS FROM ECG AND ORF N AND NW TO RIC
AND SBY. A FEW HOLES IN THE CLOUD DECK AT ECG AND ORF HAS ALLOWED
CONDITIONS AT BOTH LOCATION TO IMPROVE TO VFR AS OF 12Z. PERIODIC
IFR CONDITIONS WILL BE POSSIBLE AT ORF THROUGH 15Z BUT TREND TAT
ORF WILL BE TOWARDS VFR WITH OCCASIONAL MVFR IN SHOWERS AT ORF
FROM LATE MORNING THROUGH THE AFTERNOON. LOCATIONS FROM PHF TO RIC
AND SBY WILL HOLD ONTO IFR CONDITIONS A BIT LONGER. PHF SHOULD
IMPROVE TO MVFR AND VFR MID TO LATE MORNING. CONDITIONS WILL BE
SLOWER TO IMPROVE AT RIC AND SBY WHERE IFR CONDITIONS MAY LINGER
THROUGH 16Z.
MOST OF THE HIGH RES MODELS SUGGESTS THAT PRECIP FOCUS WILL SHIFT
TO THE NORTH AND WEST THIS AFTERNOON AS WARM FRONT LIFTS
NORTHWARD AHEAD OF WEAKENING UPR TROF FROM THE TN VLY. THIS SHOULD
LIMIT PRECIP COVERAGE AT TERMINALS IN THE 12Z-00Z TIME
FRAME...ALTHOUGH SCTD SHWRS/ISOLD TSTM PSBL AT KSBY THROUGH 18Z...AND
AT KRIC AFTER 21Z.
REGION IN WARM SECTOR MON THROUGH WED WITH SCTD...MORE
DIURNAL...SHWR/TSTM ACTIVITY...BUT MAINLY VFR/MVFR CONDITIONS.
&&
.MARINE...
S/SE WINDS PREVAIL ACROSS THE MARINE AREA THIS MORNING...WITH
SPEEDS BELOW SCA CRITERIA EVERYWHERE EVEN INTO THE AFTERNOON. WINDS
GENERALLY 10 KT THROUGH LATE MORNING INCREASING TO 10-15KT ON THE
BAY/RIVERS/SOUND...AND 10-20 KT ON THE OCEAN /HIGHEST N OF CAPE
CHARLES LIGHT/. THESE CONDITIONS EXPECTED TO PERSIST NEXT 2-3
DAYS...BEFORE WINDS BECOME SSWLY/SWLY IN THE TUE TIME FRAME.
SEAS ON THE COASTAL WATERS CONTINUE TO RUN AROUND 4-5 FEET AND
HAVE BEEN SLOWLY DECREASING OVER THE LAST FEW HOURS. WIND FORECASTS
DO NOT APPEAR TO BE SUFFICIENT TO CAUSE SEAS TO INCREASE TO 5+
FEET. HOWEVER...WAVEWATCH GUIDANCE PERSISTS IN PLACING MOST OF THE
COASTAL WATERS IN 5-6 FOOT SEAS TODAY/TONIGHT. WILL MAINTAIN SCA
FOR THE NRN 2 CSTL ZONES FOR SEAS THROUGH 00Z MON AS WINDS MAY
TEMPORARILY INCREASE THIS AFTERNOON PUSHING SEAS IN THE NORTH OF
NEAR 5 FT. SEAS EXPECTED TO SUBSIDE BELOW 5 FEET AFTER 00Z MON.
&&
.HYDROLOGY...
RIVER LEVEL FORECASTS HAVE BEEN LOWERED SUBSTANTIALLY DUE TO LACK
OF SIGNIFICANT RAINFALL IN THE HEADWATERS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ650.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ652.
&&
$$
SYNOPSIS...LKB/LSA
NEAR TERM...SAM/LSA
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...JAO/WRS
MARINE...WRS
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1003 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK FRONT REMAINS NEARLY STATIONARY OVER NORTH CAROLINA THIS
MORNING. THIS FRONT IS EXPECTED TO LIFT TO THE NORTH TODAY...AND
MOVE NORTH OF THE REGION BY MONDAY AFTERNOON. A RIDGE OF HIGH
PRESSURE OFF THE SOUTHEAST COAST WILL PREVAIL INTO THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10AM UPDATE...MADE SMALL CHANGES TO THE FORECAST AND BUMPED POPS
UP SLIGHTLY OVER SOUTHEAST PORTIONS SO THAT THE ENTIRE CWA HAS
LIKELY SHOWERS. MOST OF THE AREA WILL REMAIN MOSTLY CLOUDY TO
CLOUDY BUT SIGNIFICANT BREAKS SHOULD CONTINUE TO APPEAR OVER SE VA
AND NE NC WHICH WILL PROMOTE SHOWER DEVELOPMENT IN THE AFTN. MAX
TEMPERATURE FORECAST REMAINS MOSTLY IN THE MID TO UPR 70S WITH NEAR
80 DEGREES EXPECTED OVER INTERIOR SOUTHEAST VIRGINIA. LOWEST
READINGS WILL BE IN NORTHERN PORTIONS AND ALONG THE COAST. CONTINUED
WITH ISOLATED THUNDER EXCEPT IN PORTIONS OF THE MD EASTERN SHORE.
WENT WITH ISOLATED DUE TO CONVERGENCE AND CAPE BEING WEAKER THAN THEY
WERE SATURDAY.
PREVIOUS DISCUSSION...
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW STUBBORN
UPPER LOW OVER WRN KY WITH A RATHER BROAD MID/UPPER LEVEL TROUGH
SITUATED FROM KY DOWN INTO THE CAROLINAS. AT THE SFC...STATIONARY
FRONT/BOUNDARY STILL LOCATED OVER NRN NC. AREA OF SHOWERS AND
EMBEDDED THUNDERSTORMS DEVELOPED ALONG THE BOUNDARY IN N CNTRL NC
EARLIER THIS MORNING...BUT HAVE SINCE WEAKENED AS THEY MOVED NORTH
INTO THE REGION. CLOUD TOPS HAVE WARMED...BUT A FEW SHALLOW
SHOWERS ONGOING OVER THE ERN SHORE...AIDED BY MID LEVEL
ENERGY/SHORTWAVE. RUC H7 OMEGA HANDLES THIS AREA OF SHOWERS
WELL...WITH THE SHOWERS PUSHING OFFSHORE IN THE NEXT FEW HOURS. IN
ADDITION...VERY MOIST BOUNDARY LAYER...WAA AND CALM WINDS HAVE
RESULTED IN AREAS OF FOG THIS MORNING...WITH SOME VISIBILITIES AS
LOW AS HALF A MILE IN THE RICHMOND AREA.
ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE DYING UPPER LOW
INTO A WARM/MOIST AIRMASS...WITH THE FIRST ARRIVING LATER THIS
MORNING. COOLING CLOUD TOPS ALREADY OBSERVED THIS MORNING OVER WRN
NC. PRECIP WATERS STILL AROUND 1.5 INCHES (+1 STD DEV). EXPECT
SHOWERS TO INCREASE IN COVERAGE ACROSS THE ERN VA PIEDMONT BY MID
MORNING. FOR THIS AFTERNOON...WEAKENING UPPER LOW WILL REMAIN IN
THE VICINITY OF WRN KY AS THE BOUNDARY BEGINS TO LIFT NWD AS A
WARM FRONT. SHORTWAVE WILL LIFT THROUGH VA...COMBINING WITH WEAK
DIVERGENCE ALOFT TO PROVIDE FORCING FOR ASCENT...ALBEIT WEAK.
HOWEVER...WITH ABUNDANT MOISTURE IN PLACE...IT WILL BE ENOUGH TO
TRIGGER ADDITIONAL SHOWERS THIS AFTERNOON...MAINLY ACROSS THE
PIEDMONT INTO CNTRL VA. INSTABILITY WILL BE LIMITED...BUT GOOD LOW
LEVEL LAPSE RATES AND THETA-E ADVECTION WILL BE ENOUGH FOR
SCATTERED AFTERNOON THUNDERSTORMS....MAINLY ACROSS SRN VA. S/SE
FLOW WILL LIMIT THE AMOUNT OF INSTABILITY ALONG THE COAST AND OVER
THE ERN SHORE. MID LEVEL WIND FIELDS ARE RATHER WEAK...SO THE
MAIN THREAT FROM THUNDERSTORMS WILL BE HEAVY RAIN.
ANOTHER CLOUDY/WET DAY WILL PREVENT TEMPS FROM REACHING THEIR FULL
POTENTIAL...WITH HIGHS GENERALLY IN THE MID/UPPER 70S. COLDER
ALONG THE IMMEDIATE COAST AND OVER THE ERN SHORE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
REMNANTS OF THE UPPER LOW WILL EJECT OVER THE APPALACHIANS SUNDAY
NIGHT INTO MONDAY AS A POTENT UPPER TROUGH REACHES THE MIDWEST. AT
THE SFC...WARM FRONT WILL LOCATE NORTH OF THE FA MONDAY AFTERNOON
AS HIGH PRESSURE LOCATED OVER THE WRN ATLANTIC EXTENDS WWD INTO
THE LOWER MID ATLANTIC AND SE STATES. WARM/MOIST AIRMASS WILL
BUILD IN AS S/SW FLOW ADVECTS DEEP MOIST FROM THE ATLANTIC...WITH
PRECIP WATER VALUES APPROACHING +1.5 STD DEV. WEAK SHORTWAVE AND
DIVERGENCE ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT...BUT
EXPECT MOST FORCING AND RESULTANT CONVECTION TO BE DIURNALLY
DRIVEN. WHILE THETA-E ADVECTION AND WARM TEMPERATURES WILL PROVIDE
MARGINAL INSTABILITY (500-1000 J/KG CAPE)...A WEAKENING MID LEVEL
WIND FIELD WILL PROVIDE LIMITED SHEAR. THE RESULT WILL BE
SCATTERED THUNDERSTORMS WITH VERY LITTLE ORGANIZATION. THE
SHORTWAVE AXIS PROGGED TO BE AROUND THE ERN VA PIEDMONT...WITH THE
BEST CHANCES FOR SHOWERS/THUNDERSTORMS BEING TO THE EAST OF THE
AXIS OVER CNTRL AND ERN VA.
TROUGH AXIS WILL LOCATE ALONG THE COAST TUESDAY AS THE CNTRL CONUS
TROUGH AMPLIFIES THE UPPER RIDGE OVER THE EAST. RESIDUAL MOISTURE
AND SUBTLE UVM WILL BE SUFFICIENT FOR SHOWERS ALONG THE COAST
TUESDAY AFTERNOON. DEWPOINTS IN THE MID 60S AND AFTERNOON TEMPS IN
THE LOW/MID 80S WILL RESULT IN GREATER INSTABILITY (~1500 J/KG
CAPE AND ~-6 LIFTED INDEX) FOR CONVECTION/THUNDERSTORMS. FORCING
WILL BE MOSTLY DIURNALLY DRIVEN. HOWEVER...SHEAR REMAINS WEAK SO
EXPECT NO ORGANIZED THUNDERSTORMS.
NEAR SEASONABLE NORMAL TEMPS MONDAY (UPPER 70S/LOW 80S) BEFORE A
WARMING TREND TUESDAY. INCREASING HEIGHTS/THICKNESSES...AS WELL AS
850 TEMPS APPROACHING +1 STD DEV...WILL RESULT IN TEMPS GENERALLY
IN THE MID 80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODELS SIMILAR OVER THIS TIME PERIOD WITH THE TIMING OF ANOTHER TROF
DEEPING AT 500 MB TOWARD FRIDAY AND SATURDAY. THIS WILL USHER A
STRONGER COLD FRONT THROUGH THE REGION FRIDAY INTO SATURDAY. THE
FRONT WILL HAVE SOME SHOWERS AND THUNDERSTORMS WITH IT AS IT MOVES
THROUGH. BEFORE THAT A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY
ACROSS THE GREAT LAKES AND NEW ENGLAND. SOUTH OF THIS AREA WILL HAVE
GENERAL SOUTH TO SOUTHWEST FLOW ACROSS THE AREA. COULD SEE AN
ISOLATED AFTERNOON THUNDERSTORM. ANY THUNDERSTORMS THAT FORM NORTH
ALONG THE BOUNDARY COULD PUSH INTO THE NORTHERN PART OF THE AREA
DURING THE EVENINGS. TEMPERATURES WILL BE AT OR ABOVE NORMAL UNTIL
THE FRONT PASSES. THEN TEMPERATURES WILL DROP BACK ON SATURDAY TO AT
OR BELOW NORMAL.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
A MIX OF VFR TO IFR CONDITIONS FROM ECG AND ORF N AND NW TO RIC
AND SBY. A FEW HOLES IN THE CLOUD DECK AT ECG AND ORF HAS ALLOWED
CONDITIONS AT BOTH LOCATION TO IMPROVE TO VFR AS OF 12Z. PERIODIC
IFR CONDITIONS WILL BE POSSIBLE AT ORF THROUGH 15Z BUT TREND TAT
ORF WILL BE TOWARDS VFR WITH OCCASIONAL MVFR IN SHOWERS AT ORF
FROM LATE MORNING THROUGH THE AFTERNOON. LOCATIONS FROM PHF TO RIC
AND SBY WILL HOLD ONTO IFR CONDITIONS A BIT LONGER. PHF SHOULD
IMPROVE TO MVFR AND VFR MID TO LATE MORNING. CONDITIONS WILL BE
SLOWER TO IMPROVE AT RIC AND SBY WHERE IFR CONDITIONS MAY LINGER
THROUGH 16Z.
MOST OF THE HIGH RES MODELS SUGGESTS THAT PRECIP FOCUS WILL SHIFT
TO THE NORTH AND WEST THIS AFTERNOON AS WARM FRONT LIFTS
NORTHWARD AHEAD OF WEAKENING UPR TROF FROM THE TN VLY. THIS SHOULD
LIMIT PRECIP COVERAGE AT TERMINALS IN THE 12Z-00Z TIME
FRAME...ALTHOUGH SCTD SHWRS/ISOLD TSTM PSBL AT KSBY THROUGH 18Z...AND
AT KRIC AFTER 21Z.
REGION IN WARM SECTOR MON THROUGH WED WITH SCTD...MORE
DIURNAL...SHWR/TSTM ACTIVITY...BUT MAINLY VFR/MVFR CONDITIONS.
&&
.MARINE...
S/SE WINDS PREVAIL ACROSS THE MARINE AREA THIS MORNING...WITH
SPEEDS BELOW SCA CRITERIA EVERYWHERE EVEN INTO THE AFTERNOON. WINDS
GENERALLY 10 KT THROUGH LATE MORNING INCREASING TO 10-15KT ON THE
BAY/RIVERS/SOUND...AND 10-20 KT ON THE OCEAN /HIGHEST N OF CAPE
CHARLES LIGHT/. THESE CONDITIONS EXPECTED TO PERSIST NEXT 2-3
DAYS...BEFORE WINDS BECOME SSWLY/SWLY IN THE TUE TIME FRAME.
SEAS ON THE COASTAL WATERS CONTINUE TO RUN AROUND 4-5 FEET AND
HAVE BEEN SLOWLY DECREASING OVER THE LAST FEW HOURS. WIND FORECASTS
DO NOT APPEAR TO BE SUFFICIENT TO CAUSE SEAS TO INCREASE TO 5+
FEET. HOWEVER...WAVEWATCH GUIDANCE PERSISTS IN PLACING MOST OF THE
COASTAL WATERS IN 5-6 FOOT SEAS TODAY/TONIGHT. WILL MAINTAIN SCA
FOR THE NRN 2 CSTL ZONES FOR SEAS THROUGH 00Z MON AS WINDS MAY
TEMPORARILY INCREASE THIS AFTERNOON PUSHING SEAS IN THE NORTH OF
NEAR 5 FT. SEAS EXPECTED TO SUBSIDE BELOW 5 FEET AFTER 00Z MON.
&&
.HYDROLOGY...
RIVER LEVEL FORECASTS HAVE BEEN LOWERED SUBSTANTIALLY DUE TO LACK
OF SIGNIFICANT RAINFALL IN THE HEADWATERS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ650.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ652.
&&
$$
SYNOPSIS...LKB/LSA
NEAR TERM...SAM/LSA
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...JAO/WRS
MARINE...WRS
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
944 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A SERIES OF SLOW MOVING DISTURBANCES WILL CROSS THROUGH THE WEEK.
THEREFORE...THE MENTION OF A SHOWER OR STORM IS POSSIBLE NEARLY
EVERY DAY. TEMPERATURES WILL BE ABOVE NORMAL MOST OF THE UPCOMING
WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
FORECAST IN GOOD SHAPE WITH TWEAKS TO POP AND SKY GRIDS TO REFLECT
LATEST TRENDS. BASED ON HRRR...MOST OF SHOWER ACTIVITY WILL BE
ACR WV AND OH TODAY WHERE THE INTERSECTION OF FORCING AND MOISTURE
IS THE GREATEST. LOW CLOUDS AND FOG WILL LIMIT INSTABILITY OVER
HIGHER TERRAIN...SO LOW PCPN PROBABILITIES CONTINUE THERE.
PREVIOUS DISCUSSION...
H5 WAVE EMBEDDED IN EAST SIDE OF UPPER RIDGE TO SLIDE SLOWLY
EASTWARD TODAY. HI RES WINDOW AND HRRR BOTH ADVERTISING WEAK
FIELDS FOR PRECIP AND CONVECTIVE FOCUS. SHOULD BE WIDELY ACTIVITY WITH
LITTLE ORGANIZATION. SINCE SHORT TERM MODELS SUGGESTING A LITTLE
BETTER CHANCE PRECIP ACROSS WESTERN HALF OF CWA...WENT WITH CHANCE
POPS WEST AND SLIGHT CHANCE EAST HALF OF CWA FOR TODAY. GIVEN
PROXIMITY OF UPPER LEVEL WAVE...SHOULD BE A LITTLE MORE FORCING
WESTERN HALF. SREF CALIBRATED THUNDER FIELD SUGGESTING A LITTLE
HIGHER PROBABILITY TODAY BUT STILL LIMITED DYNAMICS. HOWEVER
CONTINUED WITH THUNDER CHANCES WITH AFTERNOON HEATING. CLOUDS
ERODING THIS MORNING WITH EXCEPTION OF SC DECK MOUNTAINS AND
EAST. WITH PROBABLE CU FIELD THIS AFTERNOON ...WENT WITH PARTLY
SUNNY BUT MOSTLY CLOUDY GARRETT...PRESTON...AND TUCKER. EXPECT
ANY PRECIPITATION TO BE SCATTERED. HOWEVER...FLOW WEAK ALOFT DUE TO OPENED
WAVE AND AREAS OF PRECIPITABLE WATER ESPECIALLY SOUTH AND WEST UP
TO 1.6 INCHES. AS A RESULT, ANY SLOW MOVING CELL COULD PRODUCE
CLOSE TO AN INCH IN VERY LOCALIZED AREAS.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
MAIN UPPER LEVEL H5 WAVE CONTINUES TO SLIDE SOUTH AND EAST THROUGH THIS
PERIOD. THIS ALLOWS H5 RIDGE TO ACTUALLY BUILD WITH RISING
HEIGHTS. WENT OPTIMISTIC AND DROPPED PRECIP CHANCES TO SLIGHT OR
BELOW (CONTINUED DIURNAL TREND AS WELL).
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
H5 RIDGE PUSHES EAST WITH VERY WEAK UPPER DISTURBANCES. SHOULD
PROVIDE FOR MOSTLY DIURNALLY DRIVEN SHOWERS OR THUNDERSTORM. BEST
CHANCE SHOWERS AND STORMS WILL COME ON THURSDAY WITH APPROACH OF
MIDWEST SYSTEM. SYSTEM SHOULD BE FINALLY CLEARING OUR REGION BY
LATE FRIDAY OR EARLY SATURDAY.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
IFR STRATUS AT DUJ IS THE LOCATION OF IMMEDIATE CONCERN. EXPECT
IT TO LIFT BY MID MRNG...WHILE FKL SHOULD STAY MVFR OR BETTER
GIVEN SUNSHINE HAS SLOWED WESTWARD PROGRESSION. VFR WEATHER IS
PREDICTED THE BALANCE OF THE DAY. ISOLD-SCT STORMS ARE FCST THIS
AFTN...BUT CONFIDENCE IS TOO LOW FOR INCLUSION. HIGHEST PROB OF
SEEING RESTRICTIONS DUE TO WX THIS AFTN WOULD BE ZZV AND MGW...BUT
EVEN THERE ITS ONLY 30 PERCENT.
LOW CONFIDENCE FORECAST TONIGHT...ESP AT THE TAIL END. DEPENDING
ON WHERE IT RAINS...LOCATIONS COULD SEE IFR FOG DEVELOP MUCH LIKE
THIS MORNING. IN ADDITION...CONTINUED MSTR ADVECTION FROM THE SSE
WILL RETURN IFR STRATUS TO DUJ/FKL AND POSSIBLY OTHER AIRPORTS AS
WELL.
.OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/...
THERE WILL BE AN INCREASING CHC FOR RESTRICTIONS IN DIURNALLY SPPRTED
SCT SHOWERS AND THUNDERSTORMS DURING THE FIRST HALF OF THE WEEK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...98
NEAR TERM...98/RJK
SHORT TERM...RJK
AVIATION...98
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
939 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK FRONT REMAINS NEARLY STATIONARY OVER NORTH CAROLINA THIS
MORNING. THIS FRONT IS EXPECTED TO LIFT TO THE NORTH TODAY...AND
MOVE NORTH OF THE REGION BY MONDAY AFTERNOON. A RIDGE OF HIGH
PRESSURE OFF THE SOUTHEAST COAST WILL PREVAIL INTO THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW STUBBORN UPPER LOW
OVER WRN KY WITH A RATHER BROAD MID/UPPER LEVEL TROUGH SITUATED
FROM KY DOWN INTO THE CAROLINAS. AT THE SFC...STATIONARY
FRONT/BOUNDARY STILL LOCATED OVER NRN NC. AREA OF SHOWERS AND
EMBEDDED THUNDERSTORMS DEVELOPED ALONG THE BOUNDARY IN N CNTRL NC
EARLIER THIS MORNING...BUT HAVE SINCE WEAKENED AS THEY MOVED NORTH
INTO THE REGION. CLOUD TOPS HAVE WARMED...BUT A FEW SHALLOW
SHOWERS ONGOING OVER THE ERN SHORE...AIDED BY MID LEVEL
ENERGY/SHORTWAVE. RUC H7 OMEGA HANDLES THIS AREA OF SHOWERS
WELL...WITH THE SHOWERS PUSHING OFFSHORE IN THE NEXT FEW HOURS. IN
ADDITION...VERY MOIST BOUNDARY LAYER...WAA AND CALM WINDS HAVE
RESULTED IN AREAS OF FOG THIS MORNING...WITH SOME VISIBILITIES AS
LOW AS HALF A MILE IN THE RICHMOND AREA.
ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE DYING UPPER LOW
INTO A WARM/MOIST AIRMASS...WITH THE FIRST ARRIVING LATER THIS
MORNING. COOLING CLOUD TOPS ALREADY OBSERVED THIS MORNING OVER WRN
NC. PRECIP WATERS STILL AROUND 1.5 INCHES (+1 STD DEV). EXPECT
SHOWERS TO INCREASE IN COVERAGE ACROSS THE ERN VA PIEDMONT BY MID
MORNING. FOR THIS AFTERNOON...WEAKENING UPPER LOW WILL REMAIN IN
THE VICINITY OF WRN KY AS THE BOUNDARY BEGINS TO LIFT NWD AS A
WARM FRONT. SHORTWAVE WILL LIFT THROUGH VA...COMBINING WITH WEAK
DIVERGENCE ALOFT TO PROVIDE FORCING FOR ASCENT...ALBEIT WEAK.
HOWEVER...WITH ABUNDANT MOISTURE IN PLACE...IT WILL BE ENOUGH TO
TRIGGER ADDITIONAL SHOWERS THIS AFTERNOON...MAINLY ACROSS THE
PIEDMONT INTO CNTRL VA. INSTABILITY WILL BE LIMITED...BUT GOOD LOW
LEVEL LAPSE RATES AND THETA-E ADVECTION WILL BE ENOUGH FOR
SCATTERED AFTERNOON THUNDERSTORMS....MAINLY ACROSS SRN VA. S/SE
FLOW WILL LIMIT THE AMOUNT OF INSTABILITY ALONG THE COAST AND OVER
THE ERN SHORE. MID LEVEL WIND FIELDS ARE RATHER WEAK...SO THE
MAIN THREAT FROM THUNDERSTORMS WILL BE HEAVY RAIN.
ANOTHER CLOUDY/WET DAY WILL PREVENT TEMPS FROM REACHING THEIR FULL
POTENTIAL...WITH HIGHS GENERALLY IN THE MID/UPPER 70S. COLDER
ALONG THE IMMEDIATE COAST AND OVER THE ERN SHORE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
REMNANTS OF THE UPPER LOW WILL EJECT OVER THE APPALACHIANS SUNDAY
NIGHT INTO MONDAY AS A POTENT UPPER TROUGH REACHES THE MIDWEST. AT
THE SFC...WARM FRONT WILL LOCATE NORTH OF THE FA MONDAY AFTERNOON
AS HIGH PRESSURE LOCATED OVER THE WRN ATLANTIC EXTENDS WWD INTO
THE LOWER MID ATLANTIC AND SE STATES. WARM/MOIST AIRMASS WILL
BUILD IN AS S/SW FLOW ADVECTS DEEP MOIST FROM THE ATLANTIC...WITH
PRECIP WATER VALUES APPROACHING +1.5 STD DEV. WEAK SHORTWAVE AND
DIVERGENCE ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT...BUT
EXPECT MOST FORCING AND RESULTANT CONVECTION TO BE DIURNALLY
DRIVEN. WHILE THETA-E ADVECTION AND WARM TEMPERATURES WILL PROVIDE
MARGINAL INSTABILITY (500-1000 J/KG CAPE)...A WEAKENING MID LEVEL
WIND FIELD WILL PROVIDE LIMITED SHEAR. THE RESULT WILL BE
SCATTERED THUNDERSTORMS WITH VERY LITTLE ORGANIZATION. THE
SHORTWAVE AXIS PROGGED TO BE AROUND THE ERN VA PIEDMONT...WITH THE
BEST CHANCES FOR SHOWERS/THUNDERSTORMS BEING TO THE EAST OF THE
AXIS OVER CNTRL AND ERN VA.
TROUGH AXIS WILL LOCATE ALONG THE COAST TUESDAY AS THE CNTRL CONUS
TROUGH AMPLIFIES THE UPPER RIDGE OVER THE EAST. RESIDUAL MOISTURE
AND SUBTLE UVM WILL BE SUFFICIENT FOR SHOWERS ALONG THE COAST
TUESDAY AFTERNOON. DEWPOINTS IN THE MID 60S AND AFTERNOON TEMPS IN
THE LOW/MID 80S WILL RESULT IN GREATER INSTABILITY (~1500 J/KG
CAPE AND ~-6 LIFTED INDEX) FOR CONVECTION/THUNDERSTORMS. FORCING
WILL BE MOSTLY DIURNALLY DRIVEN. HOWEVER...SHEAR REMAINS WEAK SO
EXPECT NO ORGANIZED THUNDERSTORMS.
NEAR SEASONABLE NORMAL TEMPS MONDAY (UPPER 70S/LOW 80S) BEFORE A
WARMING TREND TUESDAY. INCREASING HEIGHTS/THICKNESSES...AS WELL AS
850 TEMPS APPROACHING +1 STD DEV...WILL RESULT IN TEMPS GENERALLY
IN THE MID 80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODELS SIMILAR OVER THIS TIME PERIOD WITH THE TIMING OF ANOTHER TROF
DEEPING AT 500 MB TOWARD FRIDAY AND SATURDAY. THIS WILL USHER A
STRONGER COLD FRONT THROUGH THE REGION FRIDAY INTO SATURDAY. THE
FRONT WILL HAVE SOME SHOWERS AND THUNDERSTORMS WITH IT AS IT MOVES
THROUGH. BEFORE THAT A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY
ACROSS THE GREAT LAKES AND NEW ENGLAND. SOUTH OF THIS AREA WILL HAVE
GENERAL SOUTH TO SOUTHWEST FLOW ACROSS THE AREA. COULD SEE AN
ISOLATED AFTERNOON THUNDERSTORM. ANY THUNDERSTORMS THAT FORM NORTH
ALONG THE BOUNDARY COULD PUSH INTO THE NORTHERN PART OF THE AREA
DURING THE EVENINGS. TEMPERATURES WILL BE AT OR ABOVE NORMAL UNTIL
THE FRONT PASSES. THEN TEMPERATURES WILL DROP BACK ON SATURDAY TO AT
OR BELOW NORMAL.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
A MIX OF VFR TO IFR CONDITIONS FROM ECG AND ORF N AND NW TO RIC
AND SBY. A FEW HOLES IN THE CLOUD DECK AT ECG AND ORF HAS ALLOWED
CONDITIONS AT BOTH LOCATION TO IMPROVE TO VFR AS OF 12Z. PERIODIC
IFR CONDITIONS WILL BE POSSIBLE AT ORF THROUGH 15Z BUT TREND TAT
ORF WILL BE TOWARDS VFR WITH OCCASIONAL MVFR IN SHOWERS AT ORF
FROM LATE MORNING THROUGH THE AFTERNOON. LOCATIONS FROM PHF TO RIC
AND SBY WILL HOLD ONTO IFR CONDITIONS A BIT LONGER. PHF SHOULD
IMPROVE TO MVFR AND VFR MID TO LATE MORNING. CONDITIONS WILL BE
SLOWER TO IMPROVE AT RIC AND SBY WHERE IFR CONDITIONS MAY LINGER
THROUGH 16Z.
MOST OF THE HIGH RES MODELS SUGGESTS THAT PRECIP FOCUS WILL SHIFT
TO THE NORTH AND WEST THIS AFTERNOON AS WARM FRONT LIFTS
NORTHWARD AHEAD OF WEAKENING UPR TROF FROM THE TN VLY. THIS SHOULD
LIMIT PRECIP COVERAGE AT TERMINALS IN THE 12Z-00Z TIME
FRAME...ALTHOUGH SCTD SHWRS/ISOLD TSTM PSBL AT KSBY THROUGH 18Z...AND
AT KRIC AFTER 21Z.
REGION IN WARM SECTOR MON THROUGH WED WITH SCTD...MORE
DIURNAL...SHWR/TSTM ACTIVITY...BUT MAINLY VFR/MVFR CONDITIONS.
&&
.MARINE...
S/SE WINDS PREVAIL ACROSS THE MARINE AREA THIS MORNING...WITH
SPEEDS BELOW SCA CRITERIA EVERYWHERE EVEN INTO THE AFTERNOON. WINDS
GENERALLY 10 KT THROUGH LATE MORNING INCREASING TO 10-15KT ON THE
BAY/RIVERS/SOUND...AND 10-20 KT ON THE OCEAN /HIGHEST N OF CAPE
CHARLES LIGHT/. THESE CONDITIONS EXPECTED TO PERSIST NEXT 2-3
DAYS...BEFORE WINDS BECOME SSWLY/SWLY IN THE TUE TIME FRAME.
SEAS ON THE COASTAL WATERS CONTINUE TO RUN AROUND 4-5 FEET AND
HAVE BEEN SLOWLY DECREASING OVER THE LAST FEW HOURS. WINDS
FORECAST DO NOT APPEAR TO BE SUFFICIENT TO CAUSE SEAS TO INCREASE
TO 5+ FEET. HOWEVER...WAVEWATCH GUIDANCE PERSISTS IN PLACING MOST
OF THE COASTAL WATERS IN 5-6 FOOT SEAS TODAY/TONIGHT. WILL
MAINTAIN SCA FOR THE NRN 2 CSTL ZONES FOR SEAS THROUGH 00Z MON AS
WINDS MAY TEMPORARILY INCREASING THIS AFTERNOON PUSHING SEAS IN
THE NORTH OF NEAR 5 FT. SEAS EXPECTED TO SUBSIDE BELOW 5 FEET
AFTER 00Z MON.
&&
.HYDROLOGY...
RAINFALL OVER THE PIEDMONT AND RIDGES TO THE WEST ARE FORECAST TO
BRING SIGNIFICANT RISES TO AREA RIVERS BY MONDAY AND TUESDAY. SOME
LOCATIONS WILL LIKELY EXPERIENCE ACTION STAGE AND MAY POSSIBLY
HAVE MINOR FLOODING. THIS WILL DEPEND ON WHICH BASINS LOCALLY
HEAVY RAINFALL SETS UP WHICH IS TOO EARLY TO DETERMINE.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ650.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ652.
&&
$$
SYNOPSIS...LKB
NEAR TERM...SAM
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...JAO/WRS
MARINE...JAO/WRS
HYDROLOGY...
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
816 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK FRONT REMAINS NEARLY STATIONARY OVER NORTH CAROLINA THIS
MORNING. THIS FRONT IS EXPECTED TO LIFT TO THE NORTH TODAY...AND
MOVE NORTH OF THE REGION BY MONDAY AFTERNOON. A RIDGE OF HIGH
PRESSURE OFF THE SOUTHEAST COAST WILL PREVAIL INTO THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW STUBBORN UPPER LOW
OVER WRN KY WITH A RATHER BROAD MID/UPPER LEVEL TROUGH SITUATED
FROM KY DOWN INTO THE CAROLINAS. AT THE SFC...STATIONARY
FRONT/BOUNDARY STILL LOCATED OVER NRN NC. AREA OF SHOWERS AND
EMBEDDED THUNDERSTORMS DEVELOPED ALONG THE BOUNDARY IN N CNTRL NC
EARLIER THIS MORNING...BUT HAVE SINCE WEAKENED AS THEY MOVED NORTH
INTO THE REGION. CLOUD TOPS HAVE WARMED...BUT A FEW SHALLOW
SHOWERS ONGOING OVER THE ERN SHORE...AIDED BY MID LEVEL
ENERGY/SHORTWAVE. RUC H7 OMEGA HANDLES THIS AREA OF SHOWERS
WELL...WITH THE SHOWERS PUSHING OFFSHORE IN THE NEXT FEW HOURS. IN
ADDITION...VERY MOIST BOUNDARY LAYER...WAA AND CALM WINDS HAVE
RESULTED IN AREAS OF FOG THIS MORNING...WITH SOME VISIBILITIES AS
LOW AS HALF A MILE IN THE RICHMOND AREA.
ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE DYING UPPER LOW
INTO A WARM/MOIST AIRMASS...WITH THE FIRST ARRIVING LATER THIS
MORNING. COOLING CLOUD TOPS ALREADY OBSERVED THIS MORNING OVER WRN
NC. PRECIP WATERS STILL AROUND 1.5 INCHES (+1 STD DEV). EXPECT
SHOWERS TO INCREASE IN COVERAGE ACROSS THE ERN VA PIEDMONT BY MID
MORNING. FOR THIS AFTERNOON...WEAKENING UPPER LOW WILL REMAIN IN
THE VICINITY OF WRN KY AS THE BOUNDARY BEGINS TO LIFT NWD AS A
WARM FRONT. SHORTWAVE WILL LIFT THROUGH VA...COMBINING WITH WEAK
DIVERGENCE ALOFT TO PROVIDE FORCING FOR ASCENT...ALBEIT WEAK.
HOWEVER...WITH ABUNDANT MOISTURE IN PLACE...IT WILL BE ENOUGH TO
TRIGGER ADDITIONAL SHOWERS THIS AFTERNOON...MAINLY ACROSS THE
PIEDMONT INTO CNTRL VA. INSTABILITY WILL BE LIMITED...BUT GOOD LOW
LEVEL LAPSE RATES AND THETA-E ADVECTION WILL BE ENOUGH FOR
SCATTERED AFTERNOON THUNDERSTORMS....MAINLY ACROSS SRN VA. S/SE
FLOW WILL LIMIT THE AMOUNT OF INSTABILITY ALONG THE COAST AND OVER
THE ERN SHORE. MID LEVEL WIND FIELDS ARE RATHER WEAK...SO THE
MAIN THREAT FROM THUNDERSTORMS WILL BE HEAVY RAIN.
ANOTHER CLOUDY/WET DAY WILL PREVENT TEMPS FROM REACHING THEIR FULL
POTENTIAL...WITH HIGHS GENERALLY IN THE MID/UPPER 70S. COLDER
ALONG THE IMMEDIATE COAST AND OVER THE ERN SHORE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
REMNANTS OF THE UPPER LOW WILL EJECT OVER THE APPALACHIANS SUNDAY
NIGHT INTO MONDAY AS A POTENT UPPER TROUGH REACHES THE MIDWEST. AT
THE SFC...WARM FRONT WILL LOCATE NORTH OF THE FA MONDAY AFTERNOON
AS HIGH PRESSURE LOCATED OVER THE WRN ATLANTIC EXTENDS WWD INTO
THE LOWER MID ATLANTIC AND SE STATES. WARM/MOIST AIRMASS WILL
BUILD IN AS S/SW FLOW ADVECTS DEEP MOIST FROM THE ATLANTIC...WITH
PRECIP WATER VALUES APPROACHING +1.5 STD DEV. WEAK SHORTWAVE AND
DIVERGENCE ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT...BUT
EXPECT MOST FORCING AND RESULTANT CONVECTION TO BE DIURNALLY
DRIVEN. WHILE THETA-E ADVECTION AND WARM TEMPERATURES WILL PROVIDE
MARGINAL INSTABILITY (500-1000 J/KG CAPE)...A WEAKENING MID LEVEL
WIND FIELD WILL PROVIDE LIMITED SHEAR. THE RESULT WILL BE
SCATTERED THUNDERSTORMS WITH VERY LITTLE ORGANIZATION. THE
SHORTWAVE AXIS PROGGED TO BE AROUND THE ERN VA PIEDMONT...WITH THE
BEST CHANCES FOR SHOWERS/THUNDERSTORMS BEING TO THE EAST OF THE
AXIS OVER CNTRL AND ERN VA.
TROUGH AXIS WILL LOCATE ALONG THE COAST TUESDAY AS THE CNTRL CONUS
TROUGH AMPLIFIES THE UPPER RIDGE OVER THE EAST. RESIDUAL MOISTURE
AND SUBTLE UVM WILL BE SUFFICIENT FOR SHOWERS ALONG THE COAST
TUESDAY AFTERNOON. DEWPOINTS IN THE MID 60S AND AFTERNOON TEMPS IN
THE LOW/MID 80S WILL RESULT IN GREATER INSTABILITY (~1500 J/KG
CAPE AND ~-6 LIFTED INDEX) FOR CONVECTION/THUNDERSTORMS. FORCING
WILL BE MOSTLY DIURNALLY DRIVEN. HOWEVER...SHEAR REMAINS WEAK SO
EXPECT NO ORGANIZED THUNDERSTORMS.
NEAR SEASONABLE NORMAL TEMPS MONDAY (UPPER 70S/LOW 80S) BEFORE A
WARMING TREND TUESDAY. INCREASING HEIGHTS/THICKNESSES...AS WELL AS
850 TEMPS APPROACHING +1 STD DEV...WILL RESULT IN TEMPS GENERALLY
IN THE MID 80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODELS SIMILAR OVER THIS TIME PERIOD WITH THE TIMING OF ANOTHER TROF
DEEPING AT 500 MB TOWARD FRIDAY AND SATURDAY. THIS WILL USHER A
STRONGER COLD FRONT THROUGH THE REGION FRIDAY INTO SATURDAY. THE
FRONT WILL HAVE SOME SHOWERS AND THUNDERSTORMS WITH IT AS IT MOVES
THROUGH. BEFORE THAT A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY
ACROSS THE GREAT LAKES AND NEW ENGLAND. SOUTH OF THIS AREA WILL HAVE
GENERAL SOUTH TO SOUTHWEST FLOW ACROSS THE AREA. COULD SEE AN
ISOLATED AFTERNOON THUNDERSTORM. ANY THUNDERSTORMS THAT FORM NORTH
ALONG THE BOUNDARY COULD PUSH INTO THE NORTHERN PART OF THE AREA
DURING THE EVENINGS. TEMPERATURES WILL BE AT OR ABOVE NORMAL UNTIL
THE FRONT PASSES. THEN TEMPERATURES WILL DROP BACK ON SATURDAY TO AT
OR BELOW NORMAL.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A MIX OF VFR TO IFR CONDITIONS FROM ECG AND ORF N AND NW TO RIC
AND SBY. A FEW HOLES IN THE CLOUD DECK AT ECG AND ORF HAS ALLOWED
CONDITIONS AT BOTH LOCATION TO IMPROVE TO VFR AS OF 12Z. PERIODIC
IFR CONDITIONS WILL BE POSSIBLE AT ORF THROUGH 15Z BUT TREND TAT
ORF WILL BE TOWARDS VFR WITH OCCASIONAL MVFR IN SHOWERS AT ORF
FROM LATE MORNING THROUGH THE AFTERNOON. LOCATIONS FROM PHF TO RIC
AND SBY WILL HOLD ONTO IFR CONDITIONS A BIT LONGER. PHF SHOULD
IMPROVE TO MVFR AND VFR MID TO LATE MORNING. CONDITIONS WILL BE
SLOWER TO IMPROVE AT RIC AND SBY WHERE IFR CONDITIONS MAY LINGER
THROUGH 16Z.
MOST OF THE HIGH RES MODELS SUGGESTS THAT PRECIP FOCUS WILL SHIFT
TO THE NORTH AND WEST THIS AFTERNOON AS WARM FRONT LIFTS
NORTHWARD AHEAD OF WEAKENING UPR TROF FROM THE TN VLY. THIS SHOULD
LIMIT PRECIP COVERAGE AT TERMINALS IN THE 12Z-00Z TIME
FRAME...ALTHOUGH SCTD SHWRS/ISOLD TSTM PSBL AT KSBY THROUGH 18Z...AND
AT KRIC AFTER 21Z.
REGION IN WARM SECTOR MON THROUGH WED WITH SCTD...MORE
DIURNAL...SHWR/TSTM ACTIVITY...BUT MAINLY VFR/MVFR CONDITIONS.
&&
.MARINE...
E/SE WINDS PREVAIL ACROSS THE MARINE AREA THIS MORNING...WITH SPEEDS
BELOW SCA CRITERIA EVERYWHERE. WIND EXPECTED TO GRADUALLY TURN TO
THE SOUTH ALL AREAS AS THE DAY PROGRESSES...AND WARM FRONT LIFTS NWD
THROUGH REGION. WINDS GENERALLY 10-15KT ON THE
BAY/RIVERS/SOUND...AND 10-20 KT ON THE OCEAN /HIGHEST N OF CAPE
CHARLES LIGHT/. THESE CONDITIONS EXPECTED TO PERSIST NEXT 2-3
DAYS...BEFORE WINDS BECOME SSWLY/SWLY IN THE TUE TIME FRAME.
BIGGEST FORECAST CONCERN THIS MORNING IS SEAS ON THE COASTAL WATERS.
WINDS FORECAST DO NOT APPEAR TO BE SUFFICIENT TO CAUSE SEAS TO
INCREASE TO 5+ FEET. HOWEVER...WAVEWATCH GUIDANCE PERSISTS IN
PLACING MOST OF THE COASTAL WATERS IN 5-6 FOOT SEAS TODAY/TONIGHT.
ATTM...WILL HAVE SCA FOR THE NRN 2 CSTL ZONES FOR SEAS THROUGH 00Z
MON. SEAS HAVE INCREASED TO AROUND 5 FEET AT 44009 AND 44014...WITH
GREATEST RISK FOR 5 FOOT SEAS IN COASTAL WATERS AREA BEING IN THE
NRN COASTAL ZONES. SEAS EXPECTED TO SUBSIDE BELOW 5 FEET AFTER 00Z
MON.
&&
.HYDROLOGY...
RAINFALL OVER THE PIEDMONT AND RIDGES TO THE WEST ARE FORECAST TO
BRING SIGNIFICANT RISES TO AREA RIVERS BY MONDAY AND TUESDAY. SOME
LOCATIONS WILL LIKELY EXPERIENCE ACTION STAGE AND MAY POSSIBLY
HAVE MINOR FLOODING. THIS WILL DEPEND ON WHICH BASINS LOCALLY
HEAVY RAINFALL SETS UP WHICH IS TOO EARLY TO DETERMINE.
&&
.EQUIPMENT...
AKQ 88D RADAR IS BACK IN SERVICE.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ650.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ652.
&&
$$
SYNOPSIS...LKB
NEAR TERM...SAM
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...JAO/WRS
MARINE...WRS
HYDROLOGY...
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
735 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A SERIES OF SLOW MOVING DISTURBANCES IN THE UPPER ATMOSPHERE WILL
DRIFT ACROSS THE REGION THROUGH MIDWEEK. TEMPERATURES IN THE
MOUNTAINS WILL BE BELOW NORMAL TODAY AND MONDAY...HOWEVER...
ELSEWHERE SEASONABLY WARM TEMPERATURES WILL CONTINUE AND THERE
WILL BE A CHANCE OF A SHOWER OR AFTERNOON THUNDERSTORM.
&&
.NEAR TERM /THROUGH TONIGHT/...
ADJUSTMENTS TO CLOUD COVER THIS MORNING...DEPICTING LARGE STRATUS
SHIELD TO THE NORTH AND EAST. UPDATED TEMPS WITH LATEST LAMP
NUMBERS.
PREVIOUS DISCUSSION...
H5 WAVE EMBEDDED IN EAST SIDE OF UPPER RIDGE TO SLIDE SLOWLY
EASTWARD TODAY. HI RES WINDOW AND HRRR BOTH ADVERTISING WEAK
FIELDS FOR PRECIP AND CONVECTIVE FOCUS. SHOULD BE WIDELY ACTIVITY WITH
LITTLE ORGANIZATION. SINCE SHORT TERM MODELS SUGGESTING A LITTLE
BETTER CHANCE PRECIP ACROSS WESTERN HALF OF CWA...WENT WITH CHANCE
POPS WEST AND SLIGHT CHANCE EAST HALF OF CWA FOR TODAY. GIVEN
PROXIMITY OF UPPER LEVEL WAVE...SHOULD BE A LITTLE MORE FORCING
WESTERN HALF. SREF CALIBRATED THUNDER FIELD SUGGESTING A LITTLE
HIGHER PROBABILITY TODAY BUT STILL LIMITED DYNAMICS. HOWEVER
CONTINUED WITH THUNDER CHANCES WITH AFTERNOON HEATING. CLOUDS
ERODING THIS MORNING WITH EXCEPTION OF SC DECK MOUNTAINS AND
EAST. WITH PROBABLE CU FIELD THIS AFTERNOON ...WENT WITH PARTLY
SUNNY BUT MOSTLY CLOUDY GARRETT...PRESTON...AND TUCKER. EXPECT
ANY PRECIPITATION TO BE SCATTERED. HOWEVER...FLOW WEAK ALOFT DUE TO OPENED
WAVE AND AREAS OF PRECIPITABLE WATER ESPECIALLY SOUTH AND WEST UP
TO 1.6 INCHES. AS A RESULT, ANY SLOW MOVING CELL COULD PRODUCE
CLOSE TO AN INCH IN VERY LOCALIZED AREAS.
ALSO...LOOKS LIKE GARRETT...PARTS OF PRESTON AND TUCKER COULD BE
(IN-CLOUD/FOG) THIS MORNING WITH SOUTHEAST WIND...VISIBILITIES DOWN.
WILL CARRY AREAS DENSE FOG AND ISSUE SPECIAL WEATHER STATEMENT.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
MAIN UPPER LEVEL H5 WAVE CONTINUES TO SLIDE SOUTH AND EAST THROUGH THIS
PERIOD. THIS ALLOWS H5 RIDGE TO ACTUALLY BUILD WITH RISING
HEIGHTS. WENT OPTIMISTIC AND DROPPED PRECIP CHANCES TO SLIGHT OR
BELOW (CONTINUED DIURNAL TREND AS WELL).
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
H5 RIDGE PUSHES EAST WITH VERY WEAK UPPER DISTURBANCES. SHOULD
PROVIDE FOR MOSTLY DIURNALLY DRIVEN SHOWERS OR THUNDERSTORM. BEST
CHANCE SHOWERS AND STORMS WILL COME ON THURSDAY WITH APPROACH OF
MIDWEST SYSTEM. SYSTEM SHOULD BE FINALLY CLEARING OUR REGION BY
LATE FRIDAY OR EARLY SATURDAY.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
IFR STRATUS AT DUJ IS THE LOCATION OF IMMEDIATE CONCERN. EXPECT
IT TO LIFT BY MID MRNG...WHILE FKL SHOULD STAY MVFR OR BETTER
GIVEN SUNSHINE HAS SLOWED WESTWARD PROGRESSION. VFR WEATHER IS
PREDICTED THE BALANCE OF THE DAY. ISOLD-SCT STORMS ARE FCST THIS
AFTN...BUT CONFIDENCE IS TOO LOW FOR INCLUSION. HIGHEST PROB OF
SEEING RESTRICTIONS DUE TO WX THIS AFTN WOULD BE ZZV AND MGW...BUT
EVEN THERE ITS ONLY 30 PERCENT.
LOW CONFIDENCE FORECAST TONIGHT...ESP AT THE TAIL END. DEPENDING
ON WHERE IT RAINS...LOCATIONS COULD SEE IFR FOG DEVELOP MUCH LIKE
THIS MORNING. IN ADDITION...CONTINUED MSTR ADVECTION FROM THE SSE
WILL RETURN IFR STRATUS TO DUJ/FKL AND POSSIBLY OTHER AIRPORTS AS
WELL.
.OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/...
THERE WILL BE AN INCREASING CHC FOR RESTRICTIONS IN DIURNALLY SPPRTED
SCT SHOWERS AND THUNDERSTORMS DURING THE FIRST HALF OF THE WEEK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AVIATION...98
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
624 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A SERIES OF SLOW MOVING DISTURBANCES IN THE UPPER ATMOSPHERE WILL
DRIFT ACROSS THE REGION THROUGH MIDWEEK. TEMPERATURES IN THE
MOUNTAINS WILL BE BELOW NORMAL TODAY AND MONDAY...HOWEVER...
ELSEWHERE SEASONABLY WARM TEMPERATURES WILL CONTINUE AND THERE
WILL BE A CHANCE OF A SHOWER OR AFTERNOON THUNDERSTORM.
&&
.NEAR TERM /THROUGH TONIGHT/...
ADJUSTMENTS TO CLOUD COVER THIS MORNING...DEPICTING LARGE STRATUS
SHIELD TO THE NORTH AND EAST. UPDATED TEMPS WITH LATEST LAMP
NUMBERS.
PREVIOUS DISCUSSION...
H5 WAVE EMBEDDED IN EAST SIDE OF UPPER RIDGE TO SLIDE SLOWLY
EASTWARD TODAY. HI RES WINDOW AND HRRR BOTH ADVERTISING WEAK
FIELDS FOR PRECIP AND CONVECTIVE FOCUS. SHOULD BE WIDELY ACTIVITY WITH
LITTLE ORGANIZATION. SINCE SHORT TERM MODELS SUGGESTING A LITTLE
BETTER CHANCE PRECIP ACROSS WESTERN HALF OF CWA...WENT WITH CHANCE
POPS WEST AND SLIGHT CHANCE EAST HALF OF CWA FOR TODAY. GIVEN
PROXIMITY OF UPPER LEVEL WAVE...SHOULD BE A LITTLE MORE FORCING
WESTERN HALF. SREF CALIBRATED THUNDER FIELD SUGGESTING A LITTLE
HIGHER PROBABILITY TODAY BUT STILL LIMITED DYNAMICS. HOWEVER
CONTINUED WITH THUNDER CHANCES WITH AFTERNOON HEATING. CLOUDS
ERODING THIS MORNING WITH EXCEPTION OF SC DECK MOUNTAINS AND
EAST. WITH PROBABLE CU FIELD THIS AFTERNOON ...WENT WITH PARTLY
SUNNY BUT MOSTLY CLOUDY GARRETT...PRESTON...AND TUCKER. EXPECT
ANY PRECIPITATION TO BE SCATTERED. HOWEVER...FLOW WEAK ALOFT DUE TO OPENED
WAVE AND AREAS OF PRECIPITABLE WATER ESPECIALLY SOUTH AND WEST UP
TO 1.6 INCHES. AS A RESULT, ANY SLOW MOVING CELL COULD PRODUCE
CLOSE TO AN INCH IN VERY LOCALIZED AREAS.
ALSO...LOOKS LIKE GARRETT...PARTS OF PRESTON AND TUCKER COULD BE
(IN-CLOUD/FOG) THIS MORNING WITH SOUTHEAST WIND...VISIBILITIES DOWN.
WILL CARRY AREAS DENSE FOG AND ISSUE SPECIAL WEATHER STATEMENT.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
MAIN UPPER LEVEL H5 WAVE CONTINUES TO SLIDE SOUTH AND EAST THROUGH THIS
PERIOD. THIS ALLOWS H5 RIDGE TO ACTUALLY BUILD WITH RISING
HEIGHTS. WENT OPTIMISTIC AND DROPPED PRECIP CHANCES TO SLIGHT OR
BELOW (CONTINUED DIURNAL TREND AS WELL).
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
H5 RIDGE PUSHES EAST WITH VERY WEAK UPPER DISTURBANCES. SHOULD
PROVIDE FOR MOSTLY DIURNALLY DRIVEN SHOWERS OR THUNDERSTORM. BEST
CHANCE SHOWERS AND STORMS WILL COME ON THURSDAY WITH APPROACH OF
MIDWEST SYSTEM. SYSTEM SHOULD BE FINALLY CLEARING OUR REGION BY
LATE FRIDAY OR EARLY SATURDAY.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
LOW CONFIDENCE FORECAST TODAY. MODELS SHOWING LOW LEVEL MOISTURE
INCREASING AT ALL PORTS AS THE NIGHT PROGRESSES. HOWEVER, CURRENTLY
THE ONLY MVFR CLOUDS ARE THOSE LEAKING OVER THE NORTHERN
RIDGES...EFFECT DUJ AND FKL. FOR THE FORECAST...WILL GO WITH VFR
CONDITIONS...EXCEPT AT THE AFOREMENTIONED PORTS...AND INCLUDE MVFR
FOG AT ZZV AND MGW THROUGH DAWN. AM CONCERNED THAT WE COULD HAVE A
LARGE AREA OF STRATUS BLOSSOM OVER THE REGION...SIMILAR TO WHAT
HAPPENED A COUPLE OF DAYS AGO. WILL LEAVE THAT TO FUTURE UPDATES DUE
TO THE LOW CONFIDENCE.
EXPECT STRATUS TO THE NORTH AND EAST TO DECAY AFTER DAWN RETURNING
ALL PORTS TO VFR. WITH NO REAL WAVE OR BOUNDARY TO SINK MY TEETH
INTO...WILL LEAVE OUT THE MENTION OF PRECIP. A SHOWER OR STORM COULD
DEVELOP WITH DAYTIME HEATING...BUT THIS WILL NEED TO BE ADDRESSED IN
FUTURE FORECASTS.
.OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/...
THERE WILL BE AN INCREASING CHC FOR RESTRICTIONS IN DIURNALLY SPPRTED
SCT SHOWERS AND THUNDERSTORMS DURING THE FIRST HALF OF THE WEEK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
424 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK FRONT REMAINS NEARLY STATIONARY OVER NORTH CAROLINA THIS
MORNING. THIS FRONT IS EXPECTED TO LIFT TO THE NORTH TODAY...AND
MOVE NORTH OF THE REGION BY MONDAY AFTERNOON. A RIDGE OF HIGH
PRESSURE OFF THE SOUTHEAST COAST WILL PREVAIL INTO THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW STUBBORN UPPER LOW
OVER WRN KY WITH A RATHER BROAD MID/UPPER LEVEL TROUGH SITUATED
FROM KY DOWN INTO THE CAROLINAS. AT THE SFC...STATIONARY
FRONT/BOUNDARY STILL LOCATED OVER NRN NC. AREA OF SHOWERS AND
EMBEDDED THUNDERSTORMS DEVELOPED ALONG THE BOUNDARY IN N CNTRL NC
EARLIER THIS MORNING...BUT HAVE SINCE WEAKENED AS THEY MOVED NORTH
INTO THE REGION. CLOUD TOPS HAVE WARMED...BUT A FEW SHALLOW
SHOWERS ONGOING OVER THE ERN SHORE...AIDED BY MID LEVEL
ENERGY/SHORTWAVE. RUC H7 OMEGA HANDLES THIS AREA OF SHOWERS
WELL...WITH THE SHOWERS PUSHING OFFSHORE IN THE NEXT FEW HOURS. IN
ADDITION...VERY MOIST BOUNDARY LAYER...WAA AND CALM WINDS HAVE
RESULTED IN AREAS OF FOG THIS MORNING...WITH SOME VISIBILITIES AS
LOW AS HALF A MILE IN THE RICHMOND AREA.
ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE DYING UPPER LOW
INTO A WARM/MOIST AIRMASS...WITH THE FIRST ARRIVING LATER THIS
MORNING. COOLING CLOUD TOPS ALREADY OBSERVED THIS MORNING OVER WRN
NC. PRECIP WATERS STILL AROUND 1.5 INCHES (+1 STD DEV). EXPECT
SHOWERS TO INCREASE IN COVERAGE ACROSS THE ERN VA PIEDMONT BY MID
MORNING. FOR THIS AFTERNOON...WEAKENING UPPER LOW WILL REMAIN IN
THE VICINITY OF WRN KY AS THE BOUNDARY BEGINS TO LIFT NWD AS A
WARM FRONT. SHORTWAVE WILL LIFT THROUGH VA...COMBINING WITH WEAK
DIVERGENCE ALOFT TO PROVIDE FORCING FOR ASCENT...ALBEIT WEAK.
HOWEVER...WITH ABUNDANT MOISTURE IN PLACE...IT WILL BE ENOUGH TO
TRIGGER ADDITIONAL SHOWERS THIS AFTERNOON...MAINLY ACROSS THE
PIEDMONT INTO CNTRL VA. INSTABILITY WILL BE LIMITED...BUT GOOD LOW
LEVEL LAPSE RATES AND THETA-E ADVECTION WILL BE ENOUGH FOR
SCATTERED AFTERNOON THUNDERSTORMS....MAINLY ACROSS SRN VA. S/SE
FLOW WILL LIMIT THE AMOUNT OF INSTABILITY ALONG THE COAST AND OVER
THE ERN SHORE. MID LEVEL WIND FIELDS ARE RATHER WEAK...SO THE
MAIN THREAT FROM THUNDERSTORMS WILL BE HEAVY RAIN.
ANOTHER CLOUDY/WET DAY WILL PREVENT TEMPS FROM REACHING THEIR FULL
POTENTIAL...WITH HIGHS GENERALLY IN THE MID/UPPER 70S. COLDER
ALONG THE IMMEDIATE COAST AND OVER THE ERN SHORE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
REMNANTS OF THE UPPER LOW WILL EJECT OVER THE APPALACHIANS SUNDAY
NIGHT INTO MONDAY AS A POTENT UPPER TROUGH REACHES THE MIDWEST. AT
THE SFC...WARM FRONT WILL LOCATE NORTH OF THE FA MONDAY AFTERNOON
AS HIGH PRESSURE LOCATED OVER THE WRN ATLANTIC EXTENDS WWD INTO
THE LOWER MID ATLANTIC AND SE STATES. WARM/MOIST AIRMASS WILL
BUILD IN AS S/SW FLOW ADVECTS DEEP MOIST FROM THE ATLANTIC...WITH
PRECIP WATER VALUES APPROACHING +1.5 STD DEV. WEAK SHORTWAVE AND
DIVERGENCE ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT...BUT
EXPECT MOST FORCING AND RESULTANT CONVECTION TO BE DIURNALLY
DRIVEN. WHILE THETA-E ADVECTION AND WARM TEMPERATURES WILL PROVIDE
MARGINAL INSTABILITY (500-1000 J/KG CAPE)...A WEAKENING MID LEVEL
WIND FIELD WILL PROVIDE LIMITED SHEAR. THE RESULT WILL BE
SCATTERED THUNDERSTORMS WITH VERY LITTLE ORGANIZATION. THE
SHORTWAVE AXIS PROGGED TO BE AROUND THE ERN VA PIEDMONT...WITH THE
BEST CHANCES FOR SHOWERS/THUNDERSTORMS BEING TO THE EAST OF THE
AXIS OVER CNTRL AND ERN VA.
TROUGH AXIS WILL LOCATE ALONG THE COAST TUESDAY AS THE CNTRL CONUS
TROUGH AMPLIFIES THE UPPER RIDGE OVER THE EAST. RESIDUAL MOISTURE
AND SUBTLE UVM WILL BE SUFFICIENT FOR SHOWERS ALONG THE COAST
TUESDAY AFTERNOON. DEWPOINTS IN THE MID 60S AND AFTERNOON TEMPS IN
THE LOW/MID 80S WILL RESULT IN GREATER INSTABILITY (~1500 J/KG
CAPE AND ~-6 LIFTED INDEX) FOR CONVECTION/THUNDERSTORMS. FORCING
WILL BE MOSTLY DIURNALLY DRIVEN. HOWEVER...SHEAR REMAINS WEAK SO
EXPECT NO ORGANIZED THUNDERSTORMS.
NEAR SEASONABLE NORMAL TEMPS MONDAY (UPPER 70S/LOW 80S) BEFORE A
WARMING TREND TUESDAY. INCREASING HEIGHTS/THICKNESSES...AS WELL AS
850 TEMPS APPROACHING +1 STD DEV...WILL RESULT IN TEMPS GENERALLY
IN THE MID 80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODELS SIMILAR OVER THIS TIME PERIOD WITH THE TIMING OF ANOTHER TROF
DEEPING AT 500 MB TOWARD FRIDAY AND SATURDAY. THIS WILL USHER A
STRONGER COLD FRONT THROUGH THE REGION FRIDAY INTO SATURDAY. THE
FRONT WILL HAVE SOME SHOWERS AND THUNDERSTORMS WITH IT AS IT MOVES
THROUGH. BEFORE THAT A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY
ACROSS THE GREAT LAKES AND NEW ENGLAND. SOUTH OF THIS AREA WILL HAVE
GENERAL SOUTH TO SOUTHWEST FLOW ACROSS THE AREA. COULD SEE AN
ISOLATED AFTERNOON THUNDERSTORM. ANY THUNDERSTORMS THAT FORM NORTH
ALONG THE BOUNDARY COULD PUSH INTO THE NORTHERN PART OF THE AREA
DURING THE EVENINGS. TEMPERATURES WILL BE AT OR ABOVE NORMAL UNTIL
THE FRONT PASSES. THEN TEMPERATURES WILL DROP BACK ON SATURDAY TO AT
OR BELOW NORMAL.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
AVIATION CONDITIONS NEXT 12 HOURS OR SO APPEAR TO BE SPLIT BETWEEN
MVFR/VFR AT KPHF/KECG/KORF AND MAINLY IFR AT KRIC/KSBY. LOOKS LIKE
KRIC WILL REMAIN IFR/LIFR THROUGH AT LEAST 12Z IN PRE-WARM FRONTAL
AIRMASS WITH SCTD SHWRS/FOG/DZ. KSBY...BASED UPON OBSERVATIONS
LAST 1-2 HOURS...WILL LIKELY OSCILLATE BETWEEN IFR AND
MVFR...ALTHOUGH IFR WILL DOMINATE IN THE 09Z-14Z TIME FRAME. THE
OTHER 3 TAFS SHOULD BE MAINLY VFR/MVFR...ALTHOUGH A HEAVIER
SHOWER/TSTM COULD BRIEFLY BRING CONDITIONS DOWN TO IFR. WITH
LITTLE FORCING THROUGH 20Z...DO NOT EXPECT A LOT OF SHWR/TSTM
ACTIVITY AT KORF/KPHF/KECG.
LATEST NAM SUGGESTS THAT PRECIP FOCUS WILL SHIFT TO THE NORTH AND
WEST AS WARM FRONT LIFTS NORTHWARD AHD OF WEAKENING UPR TROF FROM
THE TN VLY. THIS SHOULD LIMIT PRECIP COVERAGE AT TERMINALS IN THE
12Z-00Z TIME FRAME...ALTHO SCTD SHWRS/ISOLD TSTM PSBL AT KSBY
THROUGH 18Z...AND AT KRIC AFTER 21Z.
REGION IN WARM SECTOR MON THROUGH WED WITH SCTD...MORE
DIURNAL...SHWR/TSTM ACTIVITY...BUT MAINLY VFR/MVFR CONDITIONS.
&&
.MARINE...
E/SE WINDS PREVAIL ACROSS THE MARINS AREA THIS MORNING...WITH SPEEDS
BELOW SCA CRITERIA EVERYWHERE. WIND EXPECTED TO GRADUALLY TURN TO
THE SOUTH ALL AREAS AS THE DAY PROGRESSES...AND WARM FRONT LIFTS NWD
THROUGH REGION. WINDS GENERALLY 10-15KT ON THE
BAY/RIVERS/SOUND...AND 10-20 KT ON THE OCEAN /HIGHEST N OF CAPE
CHARLES LIGHT/. THESE CONDITIONS EXPECTED TO PERSIST NEXT 2-3
DAYS...BEFORE WINDS BECOME SSWLY/SWLY IN THE TUE TIME FRAME.
BIGGEST FORECAST CONCERN THIS MORNING IS SEAS ON THE COASTAL WATERS.
WINDS FORECAST DO NOT APPEAR TO BE SUFFICIENT TO CAUSE SEAS TO
INCREASE TO 5+ FEET. HOWEVER...WAVEWATCH GUIDANCE PERSISTS IN
PLACING MOST OF THE COASTAL WATERS IN 5-6 FOOT SEAS TODAY/TONIGHT.
ATTM...WILL HAVE SCA FOR THE NRN 2 CSTL ZONES FOR SEAS THROUGH 00Z
MON. SEAS HAVE INCREASED TO AROUND 5 FEET AT 44009 AND 44014...WITH
GREATEST RISK FOR 5 FOOT SEAS IN COASTAL WATERS AREA BEING IN THE
NRN COASTAL ZONES. SEAS EXPECTED TO SUBSIDE BELOW 5 FEET AFTER 00Z
MON.
&&
.HYDROLOGY...
RAINFALL OVER THE PIEDMONT AND RIDGES TO THE WEST ARE FORECAST TO
BRING SIGNIFICANT RISES TO AREA RIVERS BY MONDAY AND TUESDAY. SOME
LOCATIONS WILL LIKELY EXPERIENCE ACTION STAGE AND MAY POSSIBLY
HAVE MINOR FLOODING. THIS WILL DEPEND ON WHICH BASINS LOCALLY
HEAVY RAINFALL SETS UP WHICH IS TOO EARLY TO DETERMINE.
&&
.EQUIPMENT...
AKQ 88D RADAR IS BACK IN SERVICE.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ650.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ652.
&&
$$
SYNOPSIS...LKB
NEAR TERM...SAM
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...WRS
MARINE...WRS
HYDROLOGY...
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
327 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A SERIES OF SLOW MOVING DISTURBANCES IN THE UPPER ATMOSPHERE WILL
DRIFT ACROSS THE REGION THROUGH MIDWEEK. TEMPERATURES IN THE
MOUNTAINS WILL BE BELOW NORMAL TODAY AND MONDAY...HOWEVER...
ELSEWHERE SEASONABLY WARM TEMPERATURES WILL CONTINUE AND THERE
WILL BE A CHANCE OF A SHOWER OR AFTERNOON THUNDERSTORM.
&&
.NEAR TERM /THROUGH TODAY/...
H5 WAVE EMBEDDED IN EAST SIDE OF UPPER RIDGE TO SLIDE SLOWLY
EASTWARD TODAY. HI RES WINDOW AND HRRR BOTH ADVERTISING WEAK
FIELDS FOR PRECIP AND CONVECTIVE FOCUS. SHOULD BE WIDELY ACTIVITY WITH
LITTLE ORGANIZATION. SINCE SHORT TERM MODELS SUGGESTING A LITTLE
BETTER CHANCE PRECIP ACROSS WESTERN HALF OF CWA...WENT WITH CHANCE
POPS WEST AND SLIGHT CHANCE EAST HALF OF CWA FOR TODAY. GIVEN
PROXIMITY OF UPPER LEVEL WAVE...SHOULD BE A LITTLE MORE FORCING
WESTERN HALF. SREF CALIBRATED THUNDER FIELD SUGGESTING A LITTLE
HIGHER PROBABILITY TODAY BUT STILL LIMITED DYNAMICS. HOWEVER
CONTINUED WITH THUNDER CHANCES WITH AFTERNOON HEATING. CLOUDS
ERODING THIS MORNING WITH EXCEPTION OF SC DECK MOUNTAINS AND
EAST. WITH PROBABLE CU FIELD THIS AFTERNOON ...WENT WITH PARTLY
SUNNY BUT MOSTLY CLOUDY GARRETT...PRESTON...AND TUCKER. EXPECT
ANY PRECIPITATION TO BE SCATTERED. HOWEVER...FLOW WEAK ALOFT DUE TO OPENED
WAVE AND AREAS OF PRECIPITABLE WATER ESPECIALLY SOUTH AND WEST UP
TO 1.6 INCHES. AS A RESULT, ANY SLOW MOVING CELL COULD PRODUCE
CLOSE TO AN INCH IN VERY LOCALIZED AREAS.
ALSO...LOOKS LIKE GARRETT...PARTS OF PRESTON AND TUCKER COULD BE
(IN-CLOUD/FOG) THIS MORNING WITH SOUTHEAST WIND...VISIBILITIES DOWN.
WILL CARRY AREAS DENSE FOG AND ISSUE SPECIAL WEATHER STATEMENT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
MAIN UPPER LEVEL H5 WAVE CONTINUES TO SLIDE SOUTH AND EAST THROUGH THIS
PERIOD. THIS ALLOWS H5 RIDGE TO ACTUALLY BUILD WITH RISING
HEIGHTS. WENT OPTIMISTIC AND DROPPED PRECIP CHANCES TO SLIGHT OR
BELOW (CONTINUED DIURNAL TREND AS WELL).
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
H5 RIDGE PUSHES EAST WITH VERY WEAK UPPER DISTURBANCES. SHOULD
PROVIDE FOR MOSTLY DIURNALLY DRIVEN SHOWERS OR THUNDERSTORM. BEST
CHANCE SHOWERS AND STORMS WILL COME ON THURSDAY WITH APPROACH OF
MIDWEST SYSTEM. SYSTEM SHOULD BE FINALLY CLEARING OUR REGION BY
LATE FRIDAY OR EARLY SATURDAY.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
LOW CONFIDENCE FORECAST TODAY. MODELS SHOWING LOW LEVEL MOISTURE
INCREASING AT ALL PORTS AS THE NIGHT PROGRESSES. HOWEVER, CURRENTLY
THE ONLY MVFR CLOUDS ARE THOSE LEAKING OVER THE NORTHERN
RIDGES...EFFECT DUJ AND FKL. FOR THE FORECAST...WILL GO WITH VFR
CONDITIONS...EXCEPT AT THE AFOREMENTIONED PORTS...AND INCLUDE MVFR
FOG AT ZZV AND MGW THROUGH DAWN. AM CONCERNED THAT WE COULD HAVE A
LARGE AREA OF STRATUS BLOSSOM OVER THE REGION...SIMILAR TO WHAT
HAPPENED A COUPLE OF DAYS AGO. WILL LEAVE THAT TO FUTURE UPDATES DUE
TO THE LOW CONFIDENCE.
EXPECT STRATUS TO THE NORTH AND EAST TO DECAY AFTER DAWN RETURNING
ALL PORTS TO VFR. WITH NO REAL WAVE OR BOUNDARY TO SINK MY TEETH
INTO...WILL LEAVE OUT THE MENTION OF PRECIP. A SHOWER OR STORM COULD
DEVELOP WITH DAYTIME HEATING...BUT THIS WILL NEED TO BE ADDRESSED IN
FUTURE FORECASTS.
.OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/...
THERE WILL BE AN INCREASING CHC FOR RESTRICTIONS IN DIURNALLY SPPRTED
SCT SHOWERS AND THUNDERSTORMS DURING THE FIRST HALF OF THE WEEK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
753 PM EDT MON MAY 20 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 409 PM EDT MON MAY 20 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CLOSED UPR LO OVER
THE NRN PLAINS UPSTREAM OF UPR RDG EXTENDING FM THE CENTRAL GRT LKS
INTO THE SE CONUS. DRY SLOTTING ALF TO THE E OF THIS FEATURE AS
SHOWN BY HIER 12Z H85 AND H7 DEWPT DEPRESSIONS AT GRB/DAVENPORT IA
HAS TENDED TO STUNT SHRA DVLPMENT OVER THE W HALF OF THE CWA...BUT
MORE PERSISTENT AXIS OF GREATER MSTR/HIER KINX OVER THE ERN CWA AND
SHRTWV MOVING NE FM WI HAS LED TO MORE SHRA/ELEVATED TS IN THAT
AREA. LO CLDS HAVE LINGERED N OF SFC WARM FNT AS WELL EXCEPT OVER
THE W...WHERE SOME LLVL DRYING/DAYTIME HEATING HAVE TENDED TO MIX
OUT THE LO CLDS AND BOOST TEMPS INTO THE 70S. TO THE W...12Z MPX
RAOB SHOWS A MUCH MOISTER AIRMASS. SOME SHRA ARE DVLPG IN WRN WI
WITH DAYTIME HEATING/DESTABILIZATION ON THE ERN EDGE OF THIS DEEPER
MSTR. FARTHER TO THE SW...ANOTHER SHRTWV IS ROTATING ARND THE CLOSED
LO AND THRU THE SCENTRAL PLAINS.
CHALLENGING FCST THRU THE SHORT TERM. BUT WITH CUTOFF LO SWIRLING TO
THE W...TENDED TO FOLLOW THE LEAST PROGRESSIVE MODELS FOR FCST
PREPARATION.
TNGT...EXPECT UPR DRY SLOT TO BRING A RELATIVELY QUIET LATE AFTN/
EARLY EVNG TIME TO THE CWA PER MOST OF RECENT HI RES GUIDANCE.
EXPECT LINGERING SHRA/TS OVER THE E TO END LATE THIS AFTN WITH
DRYING AT H85-7 SLOWLY PUSHING AXIS OF HIER MSTR TO THE E. SHRA NOW
DVLPG IN WRN WI E OF MOISTER AIRMASS SHOWN ON THE 12Z MPX RAOB AND
NEAR THE WRN EDGE OF THE DRY SLOT MAY IMPACT THE WRN ZNS THIS EVNG
AS THEY DRIFT NWD IN THE SLY FLOW ALF E OF THE UPR LO...SO CARRIED
CHC POPS IN THIS AREA THRU THE EVNG. LATER TNGT...PREFERRED 12Z
GFS/REG CNDN MODELS SHOW MORE SHRA/TS ARRIVING OVER THE SCENTRAL
COUNTIES AS SHRTWV NOW MOVING THRU THE SCENTRAL PLAINS ACCOMPANIED
BY JET MAX/UPR DVGC CORE ROTATES NEWD AHEAD OF THE NEARLY STNRY
CLOSED LO TO THE W. FCST LIKELY POPS ARRIVING LATE IN THIS AREA.
OTRW..TENDED TOWARD THE HIER END OF GUIDANCE FOR MIN TEMPS EXCEPT
NEAR THE GREAT LKS.
TUE...SHRA/SOME TS ASSOCIATED WITH DISTURBANCE LIFTING NEWD E OF THE
MAIN CLOSED LO WL IMPACT MAINLY THE CENTRAL/ERN ZNS IN THE MRNG
BEFORE GIVING WAY TO MID LVL DRYING. APRCH OF ANOTHER DISTURBANCE FM
THE SSW ROTATING ARND THE CLOSED LO MAY BRING ANOTHER BATCH OF
SHRA/TS NEAR THE WI BORDER LATER IN THE DAY. HI TEMPS FCST WL BE
TRICKY. THE CNDN MODEL HINTS AT MORE OF A SFC WAVE RIDING THRU THE
ECENTRAL AND HINTS THERE COULD BE MORE SUNSHINE IN THIS AREA IN THE
AFTN. RIGHT NOW...PLAYED THE FCST FOR MORE CLDS/A LLVL NE FLOW OFF
THE COOL WATERS OF LK SUP TO THE N OF STNRY FNT JUST TO THE W.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 409 PM EDT MON MAY 20 2013
THE FOCUS OF THE LONG TERM FORECAST THIS WEEK WILL BE THE PASSING OF
A LOW PRESSURE SYSTEM ACROSS THE GREAT LAKES REGION. CLOSED 500MB
LOW OVER THE NORTHERN PLAINS THIS AFTERNOON WILL MAKE ITS WAY JUST
SOUTH OF UPPER MICHIGAN ON WEDNESDAY...GRADUALLY FILLING AS IT
REACHES THE EASTERN SEABOARD BY FRIDAY AFTERNOON. THIS LOW EXTENDS
FROM A TROUGH ASSOCIATED WITH STRONGER LOW PRESSURE SITUATED OVER
NORTHERN QUEBEC. AT THE 300MB LEVEL LEFT EXIT REGION DIVERGENCE HAS
HELPED WITH THE DEVELOPMENT OF THE LOW PRESSURE SYSTEM OVER THE
PLAINS. THIS JET WILL SHIFT NORTHWARD AND BY WEDNESDAY UPPER
MICHIGAN WILL BE SLIGHTLY NORTH OF THE BEST UPPER LEVEL SUPPORT...IN
THE RIGHT ENTRANCE REGION. 850-500MB QVECTOR CONVERGENCE SHOWS BEST
LIFT GENERALLY ALONG SOUTHWESTERN-SOUTHERN UPPER MI/LOWER
MI/WISCONSIN ACCORDINGLY. MEANWHILE...A WEAK SURFACE LOW DEVELOPING
IN THE PLAINS MOVES NORTHWARD ALONG THE TROUGH...PASSING THROUGH
LOWER MI AND THE LOWER GREAT LAKES WEDNESDAY AFTERNOON INTO
WEDNESDAY NIGHT. MODEL SOUNDINGS SHOW ABUNDANT MOISTURE REMAINS
THROUGH ALL OF WEDNESDAY FOR CENTRAL/EASTERN UPPER MI BEFORE THE
VERY DRY AIRMASS/HIGH PRESSURE ARRIVES WEDNESDAY NIGHT/THURSDAY.
PWATS DURING THIS TIME STILL REMAIN AS HIGH AS 150 PERCENT OF
NORMAL. HAVE A DIMINISHING TREND FOR POPS FROM WEDNESDAY AFTERNOON
ONWARD AS DRY AIR INFILTRATES THE AREA AND THE SFC LOW EXITS THE
REGION. ADDITIONALLY...WITH ABUNDANT MOISTURE IN PLACE EXPECTING FOG
ACROSS LAKE SUPERIOR AND LAKE MICHIGAN FOR TUESDAY NIGHT/EARLY
WEDNESDAY AFTERNOON. ONCE THE DRIER AIR MOVES IN THE FOG WILL
DISSIPATE.
UPPER LEVEL HIGH OVER THE CANADIAN PRAIRIE WILL SINK SOUTHWARD AND
MERGE WITH THE BUILDING RIDGE OVER THE CENTRAL UNITED STATES ON
THURSDAY MORNING...BRINGING AN END TO PRECIPITATION FOR UPPER MI.
WITH DRY AIR SCOURING OUT THE CLOUDS...NORTHERLY WINDS...AND 850MB
TEMPS AROUND 2-4C...THURSDAY AFTERNOON LOOKS TO BE MOSTLY SUNNY WITH
TEMPS IN THE MID-UPPER 50S AND MAYBE EVEN LOW 60S....BELOW NORMAL BY
LATE MAY STANDARDS. MIXED LAYER DEWPOINTS BRING DEWPOINTS INTO THE
UPPER 20S/30S WHICH BRINGS MINIMUM RH FIELDS TO 30-40 PERCENT FOR
MID AFTERNOON ON THURSDAY.
A SHORTWAVE ROTATING AROUND THE 500MB LOW IN QUEBEC WILL PASS
OVERHEAD FRIDAY AFTERNOON BUT WITH DRY AIR FIRMLY IN PLACE NOTHING
WILL COME OF IT BEYOND SOME SCATTERED CLOUDS. AFTER FRIDAY THE UPPER
LEVEL RIDGE WILL SPRAWL ACROSS MUCH OF THE CENTRAL AND EASTERN
UNITED STATES. THIS WILL KEEP A DRIER AIRMASS IN PLACE AND KEEP
CONDITIONS QUIET THROUGH SATURDAY AFTERNOON. A LOW PRESSURE
TROUGH/SHORTWAVE WILL MOVE INTO THE GREAT LAKES AREA SATURDAY
EVENING INTO MONDAY...BRINGING A CHANCE FOR RAIN SHOWERS INTO THE
CWA.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 753 PM EDT MON MAY 20 2013
AVIATION FCST WILL CONTINUE TO BE CHALLENING THRU THIS PERIOD. WITH
EASTERLY UPSLOPE WINDS DOMINATING AT KCMX THRU THE NIGHT...VLIFR
CONDITIONS WILL LIKELY CONTINUE TO PREVAIL. MAY SEE SOME IMPROVEMENT
TUE MORNING AND MAYBE MORE SO TUE AFTN AS LOW-LEVEL WINDS BACK A
LITTLE MORE TO THE NE AND DIMINISH THE UPSLOPING. EXPECT SOME SHRA
AT TIMES...ESPECIALLY THIS EVENING AND THEN TUE MORNING. AT KIWD...
SHRA OVER THE NEXT FEW HRS WILL RESULT IN OCNL MVFR CONDITIONS.
OTHERWISE...VFR CONDITIONS SHOULD FALL TO MVFR THAN IFR OVERNIGHT AS
WINDS SHIFT TO THE NE...BRINGING COOL/MOIST AIR OFF LAKE SUPERIOR.
MAY SEE IMPROVEMENT TO LOW MVFR TUE AFTN. AT KSAW...STRATUS PATCHES
LURKING TO THE E AND SE SHOULD SPREAD/EXPAND NW THIS EVENING AS
DAYTIME HEATING COMES TO AN END. EXPECT CONDITIONS TO FALL TO MVFR
THEN IFR BY MID/LATE EVENING. PERIOD OF SHRA/LIFR CONDITIONS WILL
OCCUR LATE TONIGHT/TUE MORNING AS DISTURBANCE LIFTS NE INTO THE
UPPER LAKES. WITH NE WINDS DURING THE DAY TUE...MAY NOT SEE
CONDITIONS IMPROVE ABOVE IFR AT KSAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT MON MAY 20 2013
NE GALES OVER FAR WESTERN LAKE SUP WITH FAVORABLE TERRAIN FUNNELING
OF THAT FLOW WILL TEND TO DIMINISH TO 20 TO 25 KT THIS EVENING WITH
WEAKENING PRES GRADIENT. WILL LET GALE WARNING EXPIRE AT 03Z.
OTHERWISE...EXPECT PATCHY FOG TO SLOWLY DISSIPATE FROM THE N BY
LATER TUE WITH GRADUAL ARRIVAL OF DRIER AIR IN PERSISTENT NE FLOW TO
THE S OF HI PRES OVER ONTARIO.
A LOW PRESSURE SYSTEM WILL PASS JUST SOUTH OF LAKE SUPERIOR
WEDNESDAY. WINDS WILL BECOME MORE NORTHERLY AS THE LOW MOVES EASTWARD
ON THURSDAY BUT ARE EXPECTED TO REMAIN LESS THAN 25 KNOTS. HIGH
PRESSURE WILL FILTER IN BEHIND THE LOW THURSDAY EVENING AND REMAIN
THROUGH THE WEEKEND...KEEPING WINDS GENERALLY LESS THAN 20 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
DENSE FOG ADVISORY UNTIL NOON EDT TUESDAY FOR LSZ243>249-263>267.
DENSE FOG ADVISORY FROM 11 PM EDT /10 PM CDT/ THIS EVENING TO
NOON EDT /11 AM CDT/ TUESDAY FOR LSZ162.
GALE WARNING UNTIL 11 PM EDT /10 PM CDT/ THIS EVENING FOR LSZ162.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...MCD
AVIATION...ROLFSON
MARINE...MCD
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
359 PM CDT SUN MAY 19 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 345 PM CDT SUN MAY 19 2013
NARROW AREA OF MODERATE TO STRONG THUNDERSTORMS NOTED ON RADAR
FROM TWIN CITIES SOUTH INTO EASTERN FREEBORN COUNTY. HRRR HANDLED
INTIATION OF THIS ACTIVITY OVER FAR NORTHERN IOWA AND FAR SOUTH
CENTRAL MN VERY WELL EARLIER THIS AFTERNOON...SO USED SAME TO
HELP PROJECT CONVECTION INTO TONIGHT ACROSS MUCH OF THE CWA.
USED GFS40 THETA E ADVECTION TO SORT OUT TIMING AND INTENSITY
OF PCPN INTO MONDAY AFTERNOON. THROTTLED BACK SOMEWHAT ON
QPF VALUES OVER PORTION OF THE FA DUE TO SLACKENING POP CHANCES
LATER TONIGHT AND AGAIN ON MONDAY. LOCAL WRF MODEL STILL INDICATING
VERY IMPRESSIVE 850MB TRANSPORT VECTOR CONVERGENCE OVER MUCH OF
THE FA LATE THIS AFTN INTO THIS EVENING...WITH SLACKENING VALUES
NOTED OVER SW PORTION OF CWA BY 06Z. WITH THAT SAID ANTICIPATE
BEST CHANCES FOR ANY FLOOD POTENTIAL FOR REMAINDER OF FLASH
FLOOD WATCH REGION WILL BE EAST OF A LINE...FROM ST CLOUD TO
HUTCHINSON...TO WINNEBAGO. 50H LOW OVER WESTERN DAKOTAS WILL
BECOME VERTICALLY STACKED WITH SFC CYCLONE BY MON/12Z TIME FRAME
ABOVE SE SODAK. SYSTEM WILL RETROGRADE INTO SE NODAK BY EARLY
MONDAY EVENING. BEST CHANCES FOR POPS CLEARLY INDICATED OVER
NORTHERN HALF OF FA MONDAY AFTN...IN ASSOCIATION WITH BEST
THETA E ADVECTION COUPLED WITH POSITION OF RIGHT REAR QUAD RELATED
TO 130KT JET CORE ABOVE NORTHERN ONTARIO.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 355 PM CDT SUN MAY 19 2013
BRIEF DISCUSSION DUE TO ONGOING STORMS. STUBBORN LOW PRESSURE SYSTEM
IN SOUTH DAKOTA LOOKS LIKE IT WILL DRIFT EAST...STILL OVER MN ON
WEDNESDAY. TROUGH AXIS SWINGS BY TO THE SOUTH EARLY WEDNESDAY...AND
HAVE THUS ENDED MENTION OF STORMS TUESDAY NIGHT. WILL KEEP MENTION
OF SHOWERS WEDNESDAY AND WED NIGHT. MOSTLY CLOUDY AND COOL WEATHER
EXPECTED AND HAVE LOWERED MAX TEMPS. UPPER LOW STILL CLOSE ENOUGH TO
MERIT KEEPING A CHANCE OF SHOWERS INTO THURSDAY IN THE EAST. THEN
UPPER RIDGE APPROACHES. CANADIAN SURFACE HIGH MAKES A GLANCING BLOW
AND WINDS MAY BE LIGHT ENOUGH THURSDAY NIGHT TO ALLOW TEMPS TO DROP
INTO THE UPPER 30S FROM MILLE LACS LAKE TO RICE LAKE AND LADYSMITH.
SOME VARIATION IN MODELS AS TO HOW LONG THE UPPER RIDGE WILL REMAIN
OVER THE AREA LATE THIS WEEK. SOME GUIDANCE SUGGESTS IT MOVING EAST
QUICKLY ENOUGH TO BRING IN ANOTHER CHANCE OF STORMS SATURDAY AND
SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1250 PM CDT SUN MAY 19 2013
WARM FRONTAL BOUNDARY WHICH WAS CATALYST FOR EARLY MORNING
MODERATE TO HEAVY RAIN ACTIVITY CURRENTLY TREKKING INTO NORTHERN
MN. ANOTHER SHORT WAVE INITIATING ADDITIONAL CONVECTIVE ACTIVITY
OVER SW MN AND WESTERN IOWA. PRETTY STEEP LAPSE RATES NOTED
THIS AFTN ACROSS THE REGION. 12Z MSP UPPER AIR SOUNDING CONFIRMING
THIS FORECAST. USED HRRR MODEL WITH NEEDED TWEAKING TO ADVECT
SECOND ROUND OF CONVECTION INTO TAF REGION MAINLY LATE THIS
AFTN-INTO THE EARLY EVENING HOURS. BEST CHANCE FOR THUNDER
WILL REMAIN SOUTH OF A LINE FROM CANBY TO LAKEVILLE TO EAU CLAIRE.
STILL MOST OF ACTIVITY WILL BE OF SHOWERY TYPE VARIETY. LOOK
FOR MVFR CIGS AND VSBYS WITH MUCH OF THIS ACTIVITY. ANOTHER
ROUND OF MAINLY SHOWERS SHOULD REAPPEAR OVER THE TAF REGION
AFTER ABOUT 08Z...AND CONTINUE UP UNTIL ABOUT 14Z. COULD
EASILY BE SEVERAL HOURS OF LOW END MVFR CIGS AT MOST LOCATIONS
WITH THIS ACTIVITY...WITH KAXN VFR. LOOK FOR A THIRD ROUND
OF CONVECTIVE ACTIVITY AFTER 19-20Z TIME FRAME ON MONDAY.
MODERATE SE FLOW WILL RELAX TO LIGHT SE FLOW OVERNIGHT...WITH
A MORE MDT SOUTHERLY TO EVEN SSW BENT ANTICIPATED BY 20/17Z
AND THEN LASTING THROUGH END OF PERIOD.
KMSP...ATMOSPHERE IS BEING PRIMED WITH HEATING FOR ADDITIONAL
CONVECTIVE ACTIVITY TO MARCH THROUGH BY LATE THIS AFTERNOON.
LOOK FOR OCNL MVFR CIGS/VSBYS WITH ISOLATED TO SCT THUNDERSTORMS.
SECOND ROUND OF CONVECTIVE ACTIVITY WILL INITIATE AROUND 08Z
TIME FRAME...WITH SLACKENING LAPSE RATES POINTING TO MAINLY
SHOWERS. MDT SE FLOW WILL DECOUPLE TO BELOW 10KTS BY 03Z...AND
RETURN TO MDT SE FLOW BY 14Z. BEST CHANCE FOR A MORE SCT SHOWER
SITUATION WILL BE SEEN ON MONDAY BETWEEN 19Z AND 23Z TIME FRAME
...WITH ONCE AGAIN OCNL MVFR CIGS/VSBYS.
/OUTLOOK FOR KMSP/
MON...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S-SSE WIND 10-15 KTS.
TUE...VFR/MVFR CIGS. SHRA/TSRA LIKELY. E-NE WIND 5 KTS.
WED...VFR/MVFR CIGS. SHRA LIKELY. NE WIND 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR MNZ041>045-047>053-
057>063-066>070-075>078-084-085-093.
WI...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR WIZ014>016-023>028.
&&
$$
SHORT TERM...AJZ
LONG TERM...TDK
AVIATION...AJZ
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
354 PM CDT SUN MAY 19 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 345 PM CDT SUN MAY 19 2013
NARROW AREA OF MODERATE TO STRONG THUNDERSTORMS NOTED ON RADAR
FROM TWIN CITIES SOUTH INTO EASTERN FREEBORN COUNTY. HRRR HANDLED
INTIATION OF THIS ACTIVITY OVER FAR NORTHERN IOWA AND FAR SOUTH
CENTRAL MN VERY WELL EARLIER THIS AFTERNOON...SO USED SAME TO
HELP PROJECT CONVECTION INTO TONIGHT ACROSS MUCH OF THE CWA.
USED GFS40 THETA E ADVECTION TO SORT OUT TIMING AND INTENSITY
OF PCPN INTO MONDAY AFTERNOON. THROTTLED BACK SOMEWHAT ON
QPF VALUES OVER PORTION OF THE FA DUE TO SLACKENING POP CHANCES
LATER TONIGHT AND AGAIN ON MONDAY. LOCAL WRF MODEL STILL INDICATING
VERY IMPRESSIVE 850MB TRANSPORT VECTOR CONVERGENCE OVER MUCH OF
THE FA LATE THIS AFTN INTO THIS EVENING...WITH SLACKENING VALUES
NOTED OVER SW PORTION OF CWA BY 06Z. WITH THAT SAID ANTICIPATE
BEST CHANCES FOR ANY FLOOD POTENTIAL FOR REMAINDER OF FLASH
FLOOD WATCH REGION WILL BE EAST OF A LINE...FROM ST CLOUD TO
HUTCHINSON...TO WINNEBAGO. 50H LOW OVER WESTERN DAKOTAS WILL
BECOME VERTICALLY STACKED WITH SFC CYCLONE BY MON/12Z TIME FRAME
ABOVE SE SODAK. SYSTEM WILL RETROGRADE INTO SE NODAK BY EARLY
MONDAY EVENING. BEST CHANCES FOR POPS CLEARLY INDICATED OVER
NORTHERN HALF OF FA MONDAY AFTN...IN ASSOCIATION WITH BEST
THETA E ADVECTION COUPLED WITH POSITION OF RIGHT REAR QUAD RELATED
TO 130KT JET CORE ABOVE NORTHERN ONTARIO.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 345 PM CDT SUN MAY 19 2013
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1250 PM CDT SUN MAY 19 2013
WARM FRONTAL BOUNDARY WHICH WAS CATALYST FOR EARLY MORNING
MODERATE TO HEAVY RAIN ACTIVITY CURRENTLY TREKKING INTO NORTHERN
MN. ANOTHER SHORT WAVE INITIATING ADDITIONAL CONVECTIVE ACTIVITY
OVER SW MN AND WESTERN IOWA. PRETTY STEEP LAPSE RATES NOTED
THIS AFTN ACROSS THE REGION. 12Z MSP UPPER AIR SOUNDING CONFIRMING
THIS FORECAST. USED HRRR MODEL WITH NEEDED TWEAKING TO ADVECT
SECOND ROUND OF CONVECTION INTO TAF REGION MAINLY LATE THIS
AFTN-INTO THE EARLY EVENING HOURS. BEST CHANCE FOR THUNDER
WILL REMAIN SOUTH OF A LINE FROM CANBY TO LAKEVILLE TO EAU CLAIRE.
STILL MOST OF ACTIVITY WILL BE OF SHOWERY TYPE VARIETY. LOOK
FOR MVFR CIGS AND VSBYS WITH MUCH OF THIS ACTIVITY. ANOTHER
ROUND OF MAINLY SHOWERS SHOULD REAPPEAR OVER THE TAF REGION
AFTER ABOUT 08Z...AND CONTINUE UP UNTIL ABOUT 14Z. COULD
EASILY BE SEVERAL HOURS OF LOW END MVFR CIGS AT MOST LOCATIONS
WITH THIS ACTIVITY...WITH KAXN VFR. LOOK FOR A THIRD ROUND
OF CONVECTIVE ACTIVITY AFTER 19-20Z TIME FRAME ON MONDAY.
MODERATE SE FLOW WILL RELAX TO LIGHT SE FLOW OVERNIGHT...WITH
A MORE MDT SOUTHERLY TO EVEN SSW BENT ANTICIPATED BY 20/17Z
AND THEN LASTING THROUGH END OF PERIOD.
KMSP...ATMOSPHERE IS BEING PRIMED WITH HEATING FOR ADDITIONAL
CONVECTIVE ACTIVITY TO MARCH THROUGH BY LATE THIS AFTERNOON.
LOOK FOR OCNL MVFR CIGS/VSBYS WITH ISOLATED TO SCT THUNDERSTORMS.
SECOND ROUND OF CONVECTIVE ACTIVITY WILL INITIATE AROUND 08Z
TIME FRAME...WITH SLACKENING LAPSE RATES POINTING TO MAINLY
SHOWERS. MDT SE FLOW WILL DECOUPLE TO BELOW 10KTS BY 03Z...AND
RETURN TO MDT SE FLOW BY 14Z. BEST CHANCE FOR A MORE SCT SHOWER
SITUATION WILL BE SEEN ON MONDAY BETWEEN 19Z AND 23Z TIME FRAME
...WITH ONCE AGAIN OCNL MVFR CIGS/VSBYS.
/OUTLOOK FOR KMSP/
MON...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S-SSE WIND 10-15 KTS.
TUE...VFR/MVFR CIGS. SHRA/TSRA LIKELY. E-NE WIND 5 KTS.
WED...VFR/MVFR CIGS. SHRA LIKELY. NE WIND 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR MNZ041>045-047>053-
057>063-066>070-075>078-084-085-093.
WI...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR WIZ014>016-023>028.
&&
$$
SHORT TERM...AJZ
LONG TERM...TDK
AVIATION...AJZ
AREA FORECAST DISCUSSION
NWS DULUTH MN
247 PM CDT SUN MAY 19 2013
.SHORT TERM....TONIGHT THROUGH TOMORROW
CURRENT WATER VAPOR AND RADAR IMAGERY SHOWS A WELL DEFINED LOW
ROTATING OVER THE DAKOTAS. THIS STRONG AND VERY SLOW MOVING SYSTEM
HAS ALLOWED FOR A SURGE OF MOISTURE INTO THE WRN GREAT LAKES REGION
WITH DEW POINTS IN THE 50S AND 60S ACROSS THE CWA.
AT 200 PM...SFC ANALYSIS SHOWED A WARM FRONT ALIGNED ALONG THE SRN DLH
CWA BORDER...GENERALLY EXTENDING FROM THE KBRD AREA....EAST TO
K04W...KHYR...AND KPHB. SOUTH OF THIS LINE WINDS WERE DUE SOUTH WITH
TEMPS IN THE UPPER 70S TO LOW 80S. NORTH OF THE FRONT...WINDS WERE
EAST WITH TEMPS IN THE 50S.
AS THE LOW IN THE DAKOTAS GRADUALLY MAKES ITS WAY EAST INTO WESTERN
MN THROUGH MONDAY...IT WILL LIFT SEVERAL WAVES OF RAIN...WITH
SCATTERED THUNDERSTORMS...ACROSS THE REGION. NAM BUFR SOUNDINGS ARE
FAVORABLE FOR ONGOING MODERATE TO HEAVY RAINFALL RATES WITH DEEPLY
SATURATED PROFILES...AND LONG-SKINNY CAPE THROUGH MONDAY EVENING. IN
ADDITION...PWAT VALUES OVER THE NEXT 24 HRS HOVER AROUND 1.25-1.50
INCHES...WHICH IS AROUND 2 SD ABOVE NORMAL FOR THIS TIME OF YEAR.
ALTHOUGH THE INSTABILITY TO SUPPORT HEAVY RAIN DIMINISHES MONDAY
NIGHT...HAVE EXPANDED THE FLASH FLOOD WATCH THROUGH TUESDAY MORNING.
EXPECTED VERY SATURATED SOILS BY THIS TIME AND ANY ADDITIONAL
RAINFALL WOULD CONTINUE TO CAUSE FLOODING PROBLEMS. THE HEAVIEST
RAIN MONDAY NIGHT IS EXPECTED ACROSS THE NRN ZONES ON THE NRN FLANK
OF THE LOW ALONG THE WARM FRONT.
.EXTENDED...MONDAY NIGHT THROUGH SUNDAY.
THE EARLY PORTION OF THIS PERIOD WILL BE DOMINATED BY THE SLOW
MOVING LOW. THE UPPER LOW WILL BE OVER THE EASTERN DAKOTAS/WESTERN
MINNESOTA AREA 00Z TUESDAY...WITH A SURFACE LOW CENTERED WHERE
NORTH/SOUTH DAKOTA AND MINNESOTA MEET. SHOWERS AND THUNDERSTORMS
WILL REMAIN LIKELY MONDAY NIGHT INTO TUESDAY. PRECIPITATION TOTALS
LOOK TO BE LIGHTER DURING THAT TIME...WITH MOST MODELS INDICATING
LESS THAN THREE QUARTERS OF AN INCH OVER THAT 24 HOUR PERIOD. THE
SURFACE LOW WILL WEAKEN TUESDAY AS IT MOVES INTO SOUTHERN MINNESOTA.
PRECIP CHANCES WILL DIMINISH OVER THE FAR NORTH...BUT REMAIN LIKELY
OVER FAR EASTERN MINNESOTA INTO NORTHWEST WISCONSIN TUESDAY NIGHT.
THE LOW WILL WEAKEN AND CONTINUE IT`S SLOW EASTWARD/SOUTHEAST TREK.
SHOWERS WILL REMAIN LIKELY OVER NORTHWEST WISCONSIN WEDNESDAY...WITH
SLIGHT CHANCES TOWARD KINL.
HIGH PRESSURE WILL BUILD IN ON THURSDAY...AND MOST AREAS SHOULD BE
DRY THEN...INTO LASTING INTO FRIDAY NIGHT.
THE GFS/ECMWF DIFFER NEXT WEEKEND...WITH THE LATEST ECMWF KEEPING
DRY HIGH PRESSURE OVER OR JUST EAST OF THE CWA VERSUS THE GFS WHICH
BRINGS SHOWERS/STORMS BACK INTO THE AREA. WE HAVE POPS IN FOR
NOW...AND WILL ADJUST AS THE WEEK PROGRESSES.
HIGHS TUESDAY WILL RANGE FROM AROUND SIXTY OVER OUR WESTERN
ZONES...TO AROUND SEVENTY NEAR PHILLIPS. ONSHORE WINDS WILL KEEP
AREAS AROUND LAKE SUPERIOR MUCH COOLER. MOSTLY SIXTIES ARE THEN
EXPECTED THROUGH THE REST OF THE PERIOD...WITH AREAS AROUND LAKE
SUPERIOR COOLER WEDNESDAY AND THURSDAY.
.PREV DISCUSSION... /ISSUED 109 PM CDT SUN MAY 19 2013/
AVIATION...18Z TAFS
A WIDE RANGE OF CONDITIONS WERE OCCURRING ACROSS THE NORTHLAND SO
FAR TODAY...WITH IFR OVER MUCH OF FAR NORTHERN MINNESOTA...AND VFR
SOUTH. CU WAS EXPANDING AND MOVING NORTH THROUGH MINNESOTA...AND
SHOULD PROVIDE MVFR CEILINGS TO KBRD. THESE CEILINGS SHOULD RISE AS THE
AFTERNOON PROGRESSES. THE IFR CEILINGS OVER FAR NORTHERN MINNESOTA
MAY ALSO LIFT FROM SOUTH TO NORTH...BUT THE LATEST RAP SUGGESTS
KINL WILL REMAIN IFR.
AREAS AROUND LAKE SUPERIOR WILL BE ANOTHER CHALLENGE WITH A MOIST
FLOW OFF OF THE LAKE. VSBYS HAVE RISEN AT MOST AREAS AROUND THE
LAKE...BUT THE MOIST FLOW MAY ALLOW VSBYS TO DROP AGAIN AT TIMES.
THIS AREA WILL BE A MAJOR CHALLENGE INTO THIS EVENING...THEN WE
EXPECT VSBYS/CEILINGS TO LOWER AGAIN.
RAIN WAS FALLING OVER PORTIONS OF NORTHERN MINNESOTA AS OF EARLY
AFTERNOON...AND WE EXPECT SHOWERS/STORMS TO EXPAND IN COVERAGE
LATER THIS AFTERNOON INTO TONIGHT. SOME OF THE STORMS COULD BE
QUITE STRONG...ESPECIALLY OVER THE SOUTHERN HALF OF THE NORTHLAND.
&&
.POINT TEMPS/POPS...
DLH 43 50 44 52 / 90 90 70 70
INL 51 58 46 59 / 90 100 70 60
BRD 54 69 51 63 / 80 80 70 70
HYR 59 76 54 68 / 80 80 70 70
ASX 49 64 46 55 / 80 80 70 70
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR MNZ010>012-018>021-
025-026-033>038.
WI...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR WIZ001-002-006>008.
LS...SMALL CRAFT ADVISORY UNTIL 5 AM CDT TUESDAY FOR LSZ121-140>148.
&&
$$
SHORT TERM...GRANING
LONG TERM....MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
109 PM CDT SUN MAY 19 2013
.AVIATION...18Z TAFS
A WIDE RANGE OF CONDITIONS WERE OCCURRING ACROSS THE NORTHLAND SO
FAR TODAY...WITH IFR OVER MUCH OF FAR NORTHERN MINNESOTA...AND VFR
SOUTH. CU WAS EXPANDING AND MOVING NORTH THROUGH MINNESOTA...AND
SHOULD PROVIDE MVFR CEILINGS TO KBRD. THESE CEILINGS SHOULD RISE AS THE
AFTERNOON PROGRESSES. THE IFR CEILINGS OVER FAR NORTHERN MINNESOTA
MAY ALSO LIFT FROM SOUTH TO NORTH...BUT THE LATEST RAP SUGGESTS
KINL WILL REMAIN IFR.
AREAS AROUND LAKE SUPERIOR WILL BE ANOTHER CHALLENGE WITH A MOIST
FLOW OFF OF THE LAKE. VSBYS HAVE RISEN AT MOST AREAS AROUND THE
LAKE...BUT THE MOIST FLOW MAY ALLOW VSBYS TO DROP AGAIN AT TIMES.
THIS AREA WILL BE A MAJOR CHALLENGE INTO THIS EVENING...THEN WE
EXPECT VSBYS/CEILINGS TO LOWER AGAIN.
RAIN WAS FALLING OVER PORTIONS OF NORTHERN MINNESOTA AS OF EARLY
AFTERNOON...AND WE EXPECT SHOWERS/STORMS TO EXPAND IN COVERAGE
LATER THIS AFTERNOON INTO TONIGHT. SOME OF THE STORMS COULD BE
QUITE STRONG...ESPECIALLY OVER THE SOUTHERN HALF OF THE NORTHLAND.
&&
.PREV DISCUSSION... /ISSUED 1101 AM CDT SUN MAY 19 2013/
UPDATE...
INCREASED POPS/QPF AMOUNTS THIS MORNING FOR NRN TIER OF COUNTIES
TODAY WHERE A REGION OF STRONG H92 MB FGEN AND H50 OMEGA HAS
ALLOWED FOR SHRA/TSTM TO CONTINUOUSLY REGENERATE AND TRAIN OVER
THE REGION. AS OF 1100 AM...AUTOMATED WEATHER STATIONS ALONG THE
BORDERLAND FROM INTL FALLS TO CRANE LAKE HAD REPORTED AROUND AN
INCH OF RAINFALL SINCE 600 AM. A FLOOD WATCH CONTINUES FOR ALL OF
THE NE MN ZONES THROUGH MONDAY EVENING.
ALLOWED THE DENSE FOG ADVISORY TO EXPIRE. HOWEVER...AREAS OF LIGHT
FOG WITH VISIBILITY OF A MILE OR LESS WILL CONTINUE TO BE FOUND
NEAR LAKE SUPERIOR THROUGH THE DAY/TONIGHT. LOCALIZED DENSE FOG WILL
PERSIST ALONG THE HIGHER TERRAIN NEAR LAKE SUPERIOR...INCLUDING
ALONG THE PATTISON RIDGE SOUTH OF SUPERIOR...ALONG THE THOMPSON
HILL IN PROCTOR...AND ALONG THE MILLER HILL IN HERMANTOWN.
PREV DISCUSSION... /ISSUED 401 AM CDT SUN MAY 19 2013/
FLASH FLOOD WATCH ISSUED FOR NORTHEAST MINNESOTA THROUGH MONDAY...
SHORT TERM...AREA OF 85H FRONTOGENESIS ACROSS NR MN CWA
CONTINUES TO PRODUCE SCTD CONVECTION ALTHOUGH AREAL COVERAGE HAS
DECREASED OVER LAST FEW HRS. MEANWHILE LARGE AREA OF RAIN AND
THUNDERSTORMS STRETCHES FROM SERN NODAK INTO SWRN MN/NWRN IOWA.
THIS IS ASSOCIATED WITH PWS AXIS AND EJECTING MID LVL SHORTWAVE
TROF. DENSE FOG STILL LINGERS NEAR LAKE SUPERIOR AND SHOULD
CONTINUE INTO MID MORNING...IF NOT LONGER.
TODAY/TONIGHT/TOMORROW...ANOMALOUS UPPER TROF OVER CTRL CONUS WILL
CONTINUE TO ADVECT PWATS IN EXCESS OF 1.5 INCHES INTO THE REGION
NEXT 48 HRS. MAIN FOCUS AT LOW LEVELS WILL BE INVERTED TROUGH
ORIGINATING FROM SFC LOW ACROSS ERN SODAK INTO NWRN MN THIS AFTN.
HAVE EXPANDED THE FFA TO INCLUDE ALL MN ZONES THROUGH MONDAY. VERY
SLOW MOVING NATURE OF SFC/MID LVL LOW...VERY HIGH PWS..AND DEEP
CYCLONIC NATURE OF UPPER FLOW WILL ENSURE A PROLONGED PERIOD OF
WET WEATHER ACROSS THE CWA. DIFFICULT TO ASCERTAIN TIMING OF
PRECIPITATION AREAS BUT WITH WARM CLOUD DEPTHS NEAR/ABOVE 3KM ANY
CONVECTION WILL HAVE ACCESS TO VERY WET PROFILES INTO MONDAY.
CONFIDENCE IS LOW/MEDIUM ON FLOOD POTENTIAL. FFG VALUES ARE
STARTING LOWEST OVER SWRN CWA HOWEVER REMAINDER OF CWA COULD
EXPERIENCE ISSUES WITH TIME DUE TO PROLONGED NATURE OF QPF
POTENTIAL. AT LOW LVLS...SFC HIGH OVER CANADA WILL SUPPLY
INCREASINGLY STRONG LOW LVL EAST/NORTHEAST FLOW INTO MN THIS
EVENING INTO MONDAY. ALTHOUGH LOW LEVEL DRY AIR WILL TRY TO MAKE
ITS AWAY INTO NERN MN...CURRENT IDEA IS THAT ANY COLD DOME
ESTABLISHED FROM LAKE WILL BE TOPPED BY ADVECTION OF WARM AND
SOMEWHAT UNSTABLE AIR ALOFT. MAY NEED TO EXTEND FFA INTO WISC
ZONES WITH AFTERNOON FORECAST UPDATES.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY.
THE MASSIVE CLOSED LOW PRESSURE SYSTEM THAT WILL COVER MUCH OF THE
CENTRAL UNITED STATES EARLY IN THE PERIOD WILL CONTINUE TO AFFECT
THE WEATHER ACROSS THE NORTHLAND FOR THE FIRST PART OF THE EXTENDED.
THE CLOSED LOW WILL BE IN SOUTH DAKOTA MONDAY NIGHT...AND MOVE
TOWARD THE IOWA/MN/SD BORDER BY 00Z WED. THE LOW WILL BEGIN TO OPEN
UP AFTER THAT...MOVING INTO SOUTHERN WISCONSIN BY 00Z THURSDAY.
SHOWERS AND THUNDERSTORMS WILL BE LIKELY FOR MUCH OF THE REGION
MONDAY NIGHT INTO WEDNESDAY...AND THEN THE SHOWERS AND THUNDERSTORMS
WILL BEGIN TO SAG TO THE SOUTH AND EAST. DRY HIGH PRESSURE WILL DRY
OUT THE NORTH ON WEDNESDAY AND WEDNESDAY NIGHT...AND ESPECIALLY ON
THURSDAY. THURSDAY THROUGH FRIDAY NIGHT SHOULD GENERALLY BE DRY AND
QUIET ACROSS THE NORTHLAND...AS HIGH PRESSURE BUILDS IN. THE NEXT
BATCH OF PRECIPITATION WILL BE POSSIBLE SATURDAY INTO SUNDAY...
ALTHOUGH THE MODELS ARE SHOWING SOME DECENT TIMING ISSUES AND
DIFFERENCES IN SURFACE LOW AND UPPER LEVEL PATTERNS. TEMPERATURES
THROUGHOUT THE EXTENDED SHOULD LARGELY BE IN THE 60S...WITH SOME
SPOTTY 70S AT TIMES...AND 40S AND 50S AT TIMES NEAR THE LAKE.
UPDATE...RETRANSMITTED NEW ZFP AFTER UPDATE OF GRIDS. POPS
MINIMAL THROUGH 12Z. TWO AREAS OF PRECIP WILL BE ACROSS NRN MN CWA
IN AREA OF 85H FRONTOGENESIS...AND OVER SWRN CORNER CLOSER TO AREA
OF INSTABILITY AND APPROACHING MCS. FFA STILL IN PLACE FOR
PROSPECT OF ANOTHER DOSE OF RAIN BETWEEN 12Z-18Z.
&&
.POINT TEMPS/POPS...
DLH 43 49 43 51 / 90 90 70 70
INL 51 56 45 61 / 80 80 70 60
BRD 54 67 49 60 / 80 80 70 70
HYR 59 73 52 64 / 80 90 70 70
ASX 51 62 45 53 / 90 90 70 70
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR MNZ010>012-018>021-
025-026-033>038.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 5 AM CDT TUESDAY FOR LSZ121-140>148.
&&
$$
SHORT TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1250 PM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 314 AM CDT SUN MAY 19 2013
TODAY-TONIGHT...UPPER LEVEL RIDGE AXIS HAS SHIFTED INTO NRN
MN...EXTENDING SE THRU CENTRAL WI...AND WILL CONTINUE TO PUSH OFF TO
THE EAST WHILE A LARGE TROUGH DIGS DEEPER AND EXPANDS OVER THE
PLAINS STATES. AT THE SFC...A LOW PRES CENTER OVER CENTRAL SD UNDER
THE UPPER LOW WILL WOBBLE OVER CENTRAL-ERN SD...WITH A WMFNT
EXTENDING OVER SRN MN SLOWLY NUDGING N. WARM AIR AND ADDITIONAL
MOISTURE CONTINUE TO SURGE NWD INTO THE REGION WITHIN MERIDIONAL
FLOW BETWEEN THE EXITING RIDGE AND STRENGTHENING TROF...EVIDENCED BY
DEWPOINTS STILL IN THE 60S AND PWATS OVER 1.25 INCHES. ALTHOUGH THE
MORE FORMIDABLE SETUP OF THE DEEPENING SFC LOW UNDER THE ROTATING
UPPER LOW IN ERN SD WILL NOT SET UP UNTIL TNGT...A FEW BANDS OF
RAIN/TSTMS WILL PUSH THRU THE REGION DURG THE DAY TDA. SOME OF THE
RAIN MAY BE HEAVY AT TIMES...AND THERE IS STILL THE SLGT RISK OF
SEVERE TSTMS. ENHANCED UPPER LEVEL JETTING COMBINED WITH SURGING
MOISTURE /HENCE GREATER INSTABILITY/ AND STEEP LAPSE RATES WILL
CONTRIBUTE TO AN OVERALL ENVIRONMENT CAPABLE OF PRODUCING LARGE HAIL
AND DAMAGING WINDS...ESPECIALLY THIS AFTN AND EVENING OVER SRN
PORTIONS OF THE MPX CWFA. RADAR WILL NEED TO BE CONTINUALLY
MONITORED FOR NOT ONLY THE DEVELOPMENT OF STRONG/SEVERE TSTMS BUT
ALSO FOR THE POTENTIAL OF TRAINING TSTMS WHICH WOULD LEAD TO HEAVY
PERSISTENT RAIN AND POSSIBLY FLOODING /SEE HYDROLOGY SECTION/. THE
RAIN SHIELD WILL BE MORE PROMINENT LATE THIS AFTN THRU TNGT AS THE
UPPER LOW DEVELOPS SEVERAL SHORTWAVE SPOKES AROUND IT THAT WILL
ROTATE THRU THE AREA WHILE LOW LEVEL CONVERGENCE IS ENHANCED ARND A
SFC TROUGH BEING DRAGGED INTO THE AREA ARND THE SD SFC LOW. THE NET
EFFECT WILL BE MORE WIDESPREAD RAIN OVERNIGHT TNGT...SOME OF WHICH
MAY BE HEAVY AT TIMES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 314 AM CDT SUN MAY 19 2013
EXPECT WEAKENING CONVECTION TO BE ONGOING ACROSS MOST OF THE AREA
MONDAY MORNING OUT AHEAD OF THE DAKOTAS SURFACE LOW AND
FRONT...ACROSS THE WARM SECTOR. SHOULD SEE DESTABILIZATION AHEAD
OF SURFACE LOW AND FRONT DURING THE DAY. THE NEARLY STATIONARY
BOUNDARY TO THE NORTH WILL EVENTUALLY GIVE WAY TO LARGE SCALE LIFT
WITH THE APPROACH OF THE UPPER TROUGH...AND SURFACE SYSTEM
OCCLUDES. CAPE SHOULD BE SUFFICIENT ALONG WITH SHEAR AS THE DAY
PROGRESSES...WITH THE GREATEST THREAT OF SEVERE MAINLY ACROSS THE
EASTERN CWA...NEAR FRONTAL/SFC LOW PRESSURE INTERSECTION. PER DAY2
OUTLOOK FROM SPC...MAIN THREAT WILL BE LARGE HAIL...STRONG
WINDS...AND HEAVY RAIN AS THE SYSTEM IS SLOW TO MAKE EASTWARD
PROGRESS. TEMPERATURES WILL DEPEND ON HOW MUCH SUNSHINE...IF ANY
OCCURS DURING THE DAY. WILL HAVE SIGNIFICANT CLOUD DEBRIS...WITH
BEST CHANCE OF SEEING SUN IN THE FAR SOUTH MONDAY AFTERNOON.
THE UPPER LOW WILL GRADUALLY SHIFT EAST AND WEAKEN AS ANOTHER
STRONG TROUGH MOVES ACROSS THE WESTERN CONUS. THIS SHOULD IMPROVE
THE WEATHER ACROSS THE MIDSECTION OF THE COUNTRY...THURSDAY AND
FRIDAY...AS RIDGING ALOFT TAKES OVER. MUCH COOLER TEMPERATURES
WILL DIVE IN BEHIND THE DEPARTING SYSTEM...MAKING FOR A COOL END
OF THE WEEK. THE 00Z DETERMINISTIC ECMWF BRINGS IN ANOTHER CHANCE
OF RAIN INTO THE AREA LATER IN THE WEEKEND...AS THE WESTERN TROUGH
MOVES SLOWLY EAST. THE GFS IS A BIT SLOWER WITH OVERALL
PROGRESSION OF THE LOW AND BREAK DOWN OF THE RIDGE. WILL START TO
BRING IN SMALL CHANCE POPS INTO MAINLY THE WESTERN CWA SATURDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1250 PM CDT SUN MAY 19 2013
WARM FRONTAL BOUNDARY WHICH WAS CATALYST FOR EARLY MORNING
MODERATE TO HEAVY RAIN ACTIVITY CURRENTLY TREKKING INTO NORTHERN
MN. ANOTHER SHORT WAVE INITIATING ADDITIONAL CONVECTIVE ACTIVITY
OVER SW MN AND WESTERN IOWA. PRETTY STEEP LAPSE RATES NOTED
THIS AFTN ACROSS THE REGION. 12Z MSP UPPER AIR SOUNDING CONFIRMING
THIS FORECAST. USED HRRR MODEL WITH NEEDED TWEAKING TO ADVECT
SECOND ROUND OF CONVECTION INTO TAF REGION MAINLY LATE THIS
AFTN-INTO THE EARLY EVENING HOURS. BEST CHANCE FOR THUNDER
WILL REMAIN SOUTH OF A LINE FROM CANBY TO LAKEVILLE TO EAU CLAIRE.
STILL MOST OF ACTIVITY WILL BE OF SHOWERY TYPE VARIETY. LOOK
FOR MVFR CIGS AND VSBYS WITH MUCH OF THIS ACTIVITY. ANOTHER
ROUND OF MAINLY SHOWERS SHOULD REAPPEAR OVER THE TAF REGION
AFTER ABOUT 08Z...AND CONTINUE UP UNTIL ABOUT 14Z. COULD
EASILY BE SEVERAL HOURS OF LOW END MVFR CIGS AT MOST LOCATIONS
WITH THIS ACTIVITY...WITH KAXN VFR. LOOK FOR A THIRD ROUND
OF CONVECTIVE ACTIVITY AFTER 19-20Z TIME FRAME ON MONDAY.
MODERATE SE FLOW WILL RELAX TO LIGHT SE FLOW OVERNIGHT...WITH
A MORE MDT SOUTHERLY TO EVEN SSW BENT ANTICIPATED BY 20/17Z
AND THEN LASTING THROUGH END OF PERIOD.
KMSP...ATMOSPHERE IS BEING PRIMED WITH HEATING FOR ADDITIONAL
CONVECTIVE ACTIVITY TO MARCH THROUGH BY LATE THIS AFTERNOON.
LOOK FOR OCNL MVFR CIGS/VSBYS WITH ISOLATED TO SCT THUNDERSTORMS.
SECOND ROUND OF CONVECTIVE ACTIVITY WILL INITIATE AROUND 08Z
TIME FRAME...WITH SLACKENING LAPSE RATES POINTING TO MAINLY
SHOWERS. MDT SE FLOW WILL DECOUPLE TO BELOW 10KTS BY 03Z...AND
RETURN TO MDT SE FLOW BY 14Z. BEST CHANCE FOR A MORE SCT SHOWER
SITUATION WILL BE SEEN ON MONDAY BETWEEN 19Z AND 23Z TIME FRAME
...WITH ONCE AGAIN OCNL MVFR CIGS/VSBYS.
/OUTLOOK FOR KMSP/
MON...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S-SSE WIND 10-15 KTS.
TUE...VFR/MVFR CIGS. SHRA/TSRA LIKELY. E-NE WIND 5 KTS.
WED...VFR/MVFR CIGS. SHRA LIKELY. NE WIND 5-10 KTS.
&&
.HYDROLOGY...
ISSUED AT 314 AM CDT SUN MAY 19 2013
MODEL GUIDANCE AND WPC QPF INDICATE WIDESPREAD 2-3 INCHES OF
ADDITIONAL RAINFALL THRU SUNDAY EVE ACRS THE ENTIRE CWFA. IN
ADDITION...CENTRAL AND ERN PORTIONS OF THE MPX CWFA RECEIVED 1-2
INCHES OF RAINFALL YESTERDAY. CONSIDERING THE RAPID INCRS IN SOIL
MOISTURE OVER CENTRAL AND NRN PORTIONS OF THE CWFA...PLUS WHAT IS
EXPECTED OVER THE NEXT 24-36 HRS...HAVE OPTED TO EXPAND AND EXTEND
THE FLASH FLOOD WATCH OVER MUCH OF THE MPX CWFA. MODEL RAINFALL
AMOUNTS ACTUALLY PIN THE LOWEST ADDITIONAL RAINFALL OVER SERN MN.
HOWEVER...IT IS THAT SAME REGION THAT ONLY 3 WEEKS AGO DEALT WITH
12-15 INCHES OF WET HEAVY SNOW...WHICH GREATLY ADDED TO SOIL
MOISTURE CAPACITY. CONFIDENCE IS NOT ALL THAT GREAT IN TRYING TO
HIGHLIGHT WHICH AREAS WOULD BE MORE SUSCEPTIBLE THAN OTHERS IN
SEEING FLASH FLOODING...BUT CONSIDERING THAT ANY TSTMS COULD
RAPIDLY PRODUCE HEAVY RAIN...AND THAT MORE WIDESPREAD RAINFALL IS
COMING LATE TNGT THRU MON EVE...FELT IT MOST PRUDENT TO EXPAND THE
AREA OF THE FLASH FLOOD WATCH TO PUT THE NOTICE OUT THAT HEAVY
RAIN COULD OCCUR AT ANY TIME AND QUICKLY EXACERBATE THE MOST MINOR
FLOODING CONCERNS INTO POTENTIAL FLASH FLOODING.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR MNZ041>045-047>053-
057>063-066>070-075>078-084-085-093.
WI...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR WIZ014>016-023>028.
&&
$$
SHORT TERM...JPC
LONG TERM...DWE
AVIATION...JPC
HYDROLOGY...JPC
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
1254 AM CDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 928 PM CDT SAT MAY 18 2013
TOOK A LOOK AT COLD POOL DRIVEN CONVECTIVE LINE JUST TO THE WEST
OF WICHITA FOR THE OVERNIGHT HOURS. AT THIS TIME BELIEVE CURRENT
NORTHEASTERLY TRACK WILL PERSIST AS IT IS WELL ALIGNED WITH
FORWARD PROPAGATING CORFIDI VECTORS CURRENTLY AND FOR THE NEXT SIX
HOURS OR SO. THIS PATH SHOULD TAKE IT THIS LINE TO THE NORTHWEST
OF THE SGF CWA. SHORT WAVE/SPEED MAX SUPPORT EMBEDDED IN THE
APPROACHING UPPER TROF ALSO SUPPORTS THIS NORTHEASTWARD
PROPAGATION. BELIEVE ANY CONVECTION THAT MAY DEVELOP OR MOVE
TOWARD THE MISSOURI AND KANSAS BORDER AREA WILL NOT BE SEVERE AS A
DRY ELEVATED MIXED LAYER WITH CIN VALUES OF 75J/KG TO 100J/KG OR
MORE REMAINS IN PLACE OVER THAT AREA. AS MENTIONED EARLIER...BEST
UPPER LEVEL SUPPORT REMAINS TO THE NORTHWEST AS WELL. LATEST MODEL
RUNS OF THE NAM..SREF...AND RAP ALSO SUPPORT THIS ANALYSIS AS
WELL.
&&
.SHORT TERM...(LATE THIS AFTERNOON THROUGH TONIGHT)
ISSUED AT 313 PM CDT SAT MAY 18 2013
A VERY WARM AND MOIST AIR MASS IS CURRENTLY IN PLACE ACROSS THE
REGION THIS AFTERNOON. TEMPERATURES ARE CURRENTLY IN THE UPPER 70S
TO THE LOWER 80S EARLY THIS AFTERNOON AND WILL CONTINUE TO WARM
INTO THE LOWER TO MIDDLE 80S. THERE ARE ALSO WARM TEMPERATURES
ALOFT WHICH IS CREATING STEEP MID LEVEL LAPSE RATES AND A VERY
UNSTABLE AIR MASS. HOWEVER...THESE WARM TEMPERATURES IN THE MID
LEVELS HAVE CREATED A STRONG CAP WHICH WILL LIMIT CONVECTIVE
DEVELOPMENT THROUGH THE REST OF THIS AFTERNOON INTO EARLY THIS
EVENING.
A STRONG LOW LEVEL JET AND ISENTROPIC LIFT WILL SPREAD INTO THE
AREA LATER THIS EVENING INTO THE OVERNIGHT HOURS. CONVECTION MAY
DEVELOP ON THE NOSE OF THE LOW LEVEL JET ACROSS KANSAS AND SPREAD
TO THE NORTHEAST. THE BETTER POTENTIAL FOR THIS ACTIVITY WILL
LIKELY BE WEST AND NORTH OF THE AREA. THERE ARE QUESTIONS IF THE
JET WILL BE ABLE TO OVERCOME THE CAP ACROSS THE AREA THIS FAR
SOUTH. THIS ACTIVITY WOULD BE ELEVATED IN NATURE.
.LONG TERM...(SUNDAY THROUGH SATURDAY)
ISSUED AT 313 PM CDT SAT MAY 18 2013
THE POTENTIAL FOR MULTIPLE SEVERE WEATHER EVENTS CONTINUE TO TAKE
SHAPE FOR LATE SUNDAY AFTERNOON THROUGH TUESDAY WITH THE POTENTIAL
FOR SEVERE THUNDERSTORMS PRODUCING LARGE HAIL...DAMAGING
WINDS...ISOLATED TORNADOES...AND FLOODING.
AN UPPER LEVEL RIDGE WILL MIGRATE EAST OF THE REGION SUNDAY WHILE
AN UPPER LEVEL TROUGH DIGS INTO THE ROCKIES. AN ISOLATED ELEVATED
STORM CANNOT BE RULED OUT SUNDAY MORNING WITH THE AID OF A LOW
LEVEL JET...AND PASSAGE OF A MINOR IMPULSE.
THE UPPER TROUGH WILL COME INTO THE PLAINS AND TAKE A MORE NEGATIVE
TILT WHILE A SURFACE LOW DEVELOPS AND TRACKS INTO EASTERN NEBRASKA.
VERY WARM AND BREEZY CONDITIONS WILL DEVELOP OUT AHEAD OF THIS
SYSTEM ACROSS THE OZARKS ON SUNDAY. THE LOWER TROPOSPHERE WILL BECOME
MODERATELY UNSTABLE BUT REMAIN CAPPED FOR MUCH OF THE DAY ACROSS
THE OZARKS AND OSAGE PLAINS.
A POWERFUL UPPER LEVEL JET WILL PUNCH INTO THE PLAINS SUNDAY
AFTERNOON AND EVENING WHILE THE SURFACE COLD FRONT EDGES EASTWARD
ACROSS EASTERN KANSAS. STRONG DEEP LAYER SHEAR GREATER THAN 40 KTS
WILL OVERSPREAD THE AREA LATE SUNDAY AFTERNOON AND LOW LEVEL SHEAR
PROFILES MAY BE ENHANCED SUNDAY EVENING AS THE LOW LEVEL JET
STRENGTHENS. MEANWHILE SOUTHEASTERN KANSAS AND SOUTHWESTERN
MISSOURI WILL BECOME POSITIONED WITHIN THE EXIT REGION OF THE
UPPER JET WHICH WILL FURTHER ENHANCE LIFT.
SURFACE BASED CAPE WILL GENERALLY RANGE FROM 2500-3000 J/KG. PROGGED
SOUNDINGS SUGGEST A SIGNIFICANT AMOUNT WILL BE AVAILABLE WITHIN THE
HAIL GROWTH LAYER WHICH COULD RESULT IN VERY LARGE HAIL.
THE OVERALL SIGNAL FOR SEVERE WEATHER REMAINS FAIRLY UNCHANGED BUT
THERE REMAINS UNCERTAINTY ON THE EXACT TIMING AND EVOLUTION OF THIS
POTENTIAL SEVERE WEATHER EVENT.
IN GENERAL EXPECT CONVECTION TO IGNITE ACROSS THE PLAINS SUNDAY
AFTERNOON THEN SPREAD EAST INTO WESTERN MISSOURI LATE SUNDAY
AFTERNOON AND EVENING AS STRONG HEIGHT FALLS SHIFT EAST AND THE
REGION COMES UNDER THE INFLUENCE OF INCREASING JET DYNAMICS.
SHEAR PROFILES SUGGEST THUNDERSTORM MODE MAY EVOLVE FROM SUPERCELLS
TO MORE OF A LINEAR CONVECTIVE COMPLEX AS CONVECTION SPREADS INTO
THE AREA. 0-3KM ENVIRONMENTAL HELICITIES OF 200-400 WILL SUPPORT THE
POTENTIAL FOR TORNADO DEVELOPMENT.
IN ANY EVENT STRONG TO SEVERE THUNDERSTORMS WILL IMPACT SOUTHEASTERN
KANSAS AND SOUTHWESTERN MISSOURI GENERALLY NORTHWEST OF A BRANSON TO
ROLLA LINE LATE SUNDAY AFTERNOON AND SUNDAY NIGHT AND ESPECIALLY
WEST OF HIGHWAY 65. AT THIS TIME IT APPEARS THE STORMS WILL ARRIVE
IN EXTREME SOUTHEASTERN KANSAS TO THE INTERSTATE 49 CORRIDOR BETWEEN
5 AND 8 PM...AND THE HIGHWAY 65 CORRIDOR BETWEEN 9 PM AND
MIDNIGHT.
ON MONDAY...THE UPPER TROUGH WILL SHIFT INTO THE NORTHERN PLAINS
WHICH WILL MAINTAIN A BELT OF WESTERLIES ACROSS THE REGION. THE
ASSOCIATED COLD FRONT WILL SAG SOUTHWARD INTO THE REGION AND BECOME
ORIENTED PARALLEL WITH THE FLOW ALOFT. AMPLE INSTABILITY AND DEEP
LAYER SHEER WILL BE IN PLACE TO SUPPORT STRONG TO SEVERE STORMS
ESPECIALLY MONDAY EVENING AS A JET STREAK COMES ACROSS EASTERN KANSAS
AND WESTERN MISSOURI. THE RISK FOR SEVERE WILL INCREASE IF AMPLE
CLEARING AND SUBSEQUENT DESTABILIZATION OCCURS.
IN ADDITION A RICH SUPPLY OF MOISTURE WILL INTERACT WITH THE FRONT
TO SUPPORT HEAVY RAINFALL RATES. GIVEN THE ORIENTATION OF THE FRONT
AND THE POTENTIAL FOR TRAINING STORMS THE RISK FOR FLOODING WILL
INCREASE MONDAY AND MONDAY NIGHT.
ON TUESDAY...MODELS DIFFER ON THE TIMING OF THE FRONTAL PASSAGE BUT
IN GENERAL HAVE SLOWED IT DOWN. THIS WILL MAINTAIN THE POTENTIAL OF
SEVERE WEATHER AND FLOODING GOING INTO TUESDAY ESPECIALLY EAST OF
HIGHWAY 65.
FOR THE REMAINDER OF NEXT WEEK...UPPER LEVEL RIDGING WILL GRADUALLY
BUILD INTO THE REGION AS THE TROUGH SHIFTS TO THE EAST. MODELS
CONTINUE SUGGEST PERIODIC CHANCES OF CONVECTION AS MINOR DISTURBANCES
COME OVER THE RIDGE BUT DETAILS ON TIMING AND COVERAGE ARE
UNCERTAIN. OTHERWISE SEASONABLY WARM WEATHER IS EXPECTED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1238 AM CDT SUN MAY 19 2013
LIGHT FOG AND MVFR VISIBILITIES WILL PERSIST ACROSS PORTIONS OF
SOUTHERN MISSOURI INTO EARLY SUNDAY MORNING. WE DO EXPECT IFR
VISIBILITIES FOR THE KBBG AERODROME...WITH OCCASIONAL LIFR. WE ARE
ALSO EXPECTING SOME LOW CLOUD DEVELOPMENT OVERNIGHT...ESPECIALLY
AROUND KBBG. MEANWHILE...AN AREA OF WEAKENING SHOWERS AND
THUNDERSTORMS MAY PUSH INTO WESTERN MISSOURI LATE TONIGHT. WE HAVE
INCLUDED A TEMPO GROUP AT KJLN TO COVER THIS. ONE ADDITIONAL
AVIATION IMPACT INTO EARLY SUNDAY MORNING WILL BE LOW LEVEL WIND
SHEAR. FLIGHT CATEGORIES WILL THEN IMPROVE TO VFR BY MID MORNING
SUNDAY WITH BRISK AND GUSTY SOUTH WINDS DEVELOPING. WE ARE THEN
EXPECTING STRONG TO SEVERE THUNDERSTORMS TO DEVELOP ACROSS KANSAS
AND OKLAHOMA LATE SUNDAY AFTERNOON AND SUNDAY EVENING. CURRENT
INDICATIONS ARE THAT A LINE OF SEVERE THUNDERSTORMS MAY IMPACT THE
AERODROMES STARTING AROUND THE END OF THE TAF PERIOD.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
UPDATE...COLUCCI
SHORT TERM...WISE
LONG TERM...FOSTER
AVIATION...SCHAUMANN
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
916 PM MDT MON MAY 20 2013
.UPDATE...
A WAVE OF RAIN ASSOCIATED WITH A TROWAL OVER EASTERN MONTANA IS
MAKING ITS WAY INTO THE CENTRAL ZONES THIS EVENING AND MAY EVEN
GET INTO THE BILLINGS VICINITY. ANOTHER WAVE IS ALSO MOVING ACROSS
THE DAKOTA BORDER INTO OUR FAR EASTERN ZONES SUCH AS CARTER AND
FALLON COUNTIES. MUCH OF THIS PRECIPITATION IS EXPECTED TO
DIMINISH AFTER MIDNIGHT AS THE GFS AND NAM HAVE INDICATED
WEAKENING ISENTROPIC LIFT ACROSS THE REGION...CONFIRMED BY RECENT
RAP MODEL ANALYSIS. IN THE FAR WEST...SOME ISOLATED SHOWERS MAY
HANG ON AND HUG THE HIGHER TERRAIN FOR AWHILE BEFORE DISSIPATING.
FOR THIS UPDATE MADE CHANGES TO OVERNIGHT POPS BASED ON RADAR
TRENDS AND RAP DATA. BT
&&
.SHORT TERM...VALID FOR TUE AND WED...
LARGE UPPER LOW CONTINUES TO HOLD FIRM ACROSS THE EASTERN DAKOTAS
THIS AFTERNOON. LARGE AREA OF WRAP AROUND RAIN AS SHOWN BY
SATELLITE AND RADAR WILL MOVE WEST AND SOUTHWEST INTO EASTERN
MONTANA FOR THE REMAINDER OF THE AFTERNOON AND THROUGH THE EVENING
HOURS. RADAR SHOWING LIGHT TO OCCASIONALLY MODERATE RAIN FALLING
FROM ABOUT ROSEBUD COUNTY EASTWARD. SOME BREAKS IN SUN WEST OF
THIS AREA HAVE RESULTED IN NUMEROUS CONVECTIVE SHOWERS WITH
ISOLATED LIGHTNING STRIKES. HAVE ADDED AN ISOLATED THUNDERSTORM TO
THE FORECAST FROM YELLOWSTONE COUNTY WESTWARD THROUGH MID EVENING
WHEN THE ATMOSPHERE SHOULD BE STABILIZING SHORTLY AFTER SUNSET.
WILL KEEP A CHANCE FOR SHOWERS AND AN ISOLATED THUNDERSTORM
THROUGH THE EVENING HOURS. RAINFALL AMOUNTS AT MILES CITY AND
BAKER SINCE MIDNIGHT HAVE BEEN SIGNIFICANT...ESPECIALLY ON AN
HOURLY BASIS. HAVE NOT HAD ANY REPORTS OF SIGNIFICANT FLOODING IN
THE BURN SCAR AREAS SO HAVE DECIDED TO CANCEL THE FLASH FLOOD
WATCH WITH THIS FORECAST ISSUANCE. AS FOR THE FLOOD ADVISORY FOR
PORTIONS OF YELLOWSTONE AND BIG HORN COUNTIES...HAVE RECENTLY
CANCELLED THAT AS WELL AS REPORTS ALONG PRYOR CREEK INDICATE VERY
LITTLE RISING OF THE CREEK AND HAVE NOT HAD ANY REPORTS OF
SIGNIFICANT FLOODING FOR THIS AREA AS WELL.
THE UPPER LOW WILL SLOWLY SHIFT EAST TONIGHT AND ESPECIALLY
TUESDAY AND BEGIN TO LOSE ITS ORGANIZATION AS WELL. WILL KEEP
LIKELY POPS FOR CUSTER AND POWDER RIVER COUNTIES EASTWARD TONIGHT
WITH LIKELY POPS TUESDAY ALONG THE DAKOTA BORDER WITH CHANCE POPS
CUSTER AND POWDER RIVER COUNTIES. FURTHER WEST...CONDITIONS LOOK
TO DRY OUT AND NOT EXPECTING AND SHOWER ACTIVITY DURING THE DAY
TUESDAY.
WEDNESDAY...PRECIP CHANCES INCREASE ONCE AGAIN BY AFTERNOON AND
INTO WEDNESDAY NIGHT. A LARGE UPPER LOW MOVES ONTO THE PACIFIC
NORTHWEST COAST AND REMAINS NEARLY STATIONARY THROUGH AT LEAST
THURSDAY. UNLIKE THIS LAST LOW WHICH WAS SLOW MOVING ACROSS
NORTHERN WYOMING INTO THE DAKOTAS THIS LOW WILL PUT OUR FORECAST
AREA UNDER A WARM SOUTH TO SOUTHWEST FLOW ALOFT. PIECES OF ENERGY
WILL ROTATE AROUND THIS LOW AND THIS COMBINED WITH A DIFFLUENT FLOW
ALOFT WILL BRING INCREASING CHANCES FOR THUNDERSTORMS. AT THIS
TIME STRONGEST DYNAMICS LOOK TO REMAIN ACROSS WESTERN MONTANA AND
IDAHO WEDNESDAY INTO WEDNESDAY NIGHT. HIGH CHANCES FOR
THUNDERSTORMS WILL EXIST FROM ABOUT BILLINGS WESTWARD WEDNESDAY
AFTERNOON AND EVENING. DYNAMICS WILL BE IN PLACE FOR POSSIBLE
SEVERE THUNDERSTORMS IN PART THANKS TO THIS LAST STORM SYSTEM
WHICH HAS PROVIDED FOR A MOIST GROUND RESULTING IN HIGHER
DEWPOINTS. FORECAST AREA SHOULD ALSO HAVE AN EASTERLY SURFACE FLOW
ALONG WITH SOME WIND SHEAR AIDING IN SEVERE INGREDIENTS. SO THE
POTENTIAL EXISTS WEDNESDAY THROUGH THE END OF THE WEEK FOR SOME
SEVERE THUNDERSTORMS. HOOLEY
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
HEIGHTS LOWER THURSDAY AS THE UPPER LEVEL TROUGH MOVES SLOWLY
EASTWARD. DIFFLUENT FLOW INCREASES WITH INCREASING SHEAR. LOW
LEVEL SOUTHEASTERLY WINDS WILL KEEP DEWPOINTS IN THE UPPER 40S TO
LOW 50S. CAPE VALUES LOOK TO BE ABOVE 1000 J/KG ACROSS PORTIONS
OF THE WEST AND CENTRAL...WITH EFFECTIVE BULK SHEAR VALUES
APPROACHING 40 KTS...SO STRONG TO SEVERE STORMS WITH GUSTY WINDS
AND LARGE HAIL ARE POSSIBLE. DID NOT MENTION SEVERE IN THE
FORECAST. WILL LET THE MID SHIFT TAKE ANOTHER LOOK.
MODELS SHOW ANOTHER WAVE MOVING THROUGH THE REGION IN SW
FLOW FRIDAY AFTERNOON/EVENING. CAPE VALUES AGAIN LOOK TO EXCEED
500 J/KG ACROSS PORTIONS OF THE CENTRAL AND EAST...WITH SURFACE
DEWPOINTS APPROACHING 50 AND BULK SHEAR VALUES OVER 30 KTS...SO
STRONG THUNDERSTORMS ARE AGAIN POSSIBLE...ESPECIALLY ACROSS THE
EASTERN HALF OF THE CWA.
MODELS BEGIN TO DIFFER A BIT IN THEIR SOLUTIONS SATURDAY THROUGH
MONDAY. THE ECMWF BUILDS SOME UPPER LEVEL RIDGING INTO THE REGION
SATURDAY AHEAD OF THE UPPER LEVEL LOW...WHICH IS PROGGED TO STALL
OVER THE PACIFIC NW. THIS WOULD LEAD TO A DRIER FORECAST THAN THE
GFS...WHICH KEEPS US IN MORE SW FLOW AND SHORTWAVE ACTIVITY. NOT
TOO CONFIDENT ABOUT WHAT WILL HAPPEN SATURDAY...SO BASICALLY
BROADBRUSHED THE CWA IN LOW POPS.
SEVERAL STRONGER PIECES OF ENERGY ARE PROGGED BY BOTH THE GFS AND
ECMWF TO SWING THROUGH THE REGION SUNDAY AND MONDAY. THOUGH THERE
ARE MODEL DIFFERENCES IN BOTH STRENGTH AND TIMING...IT DOES LOOK
LIKE THERE MAY BE SOME STRONG UPPER LEVEL DIFFLUENCE AS WELL AS
INCREASED SE LOW LEVEL FLOW BRINGING IN ADDITIONAL MOISTURE. CAPE
AND AND EFFECTIVE BULK SHEAR VALUES ARE SUPPORTIVE OF STRONG
STORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS...SO I
KEPT AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS IN THE FORECAST
BOTH SUNDAY AND MONDAY.
AS FOR TEMPS...LOOK FOR A WARMING TREND THROUGH THE EXTENDED.
TEMPS LOOKED A FEW DEGREES TOO COOL...SO I RAISED THEM A BIT. STC
&&
.AVIATION...
SLOW MOVING UPPER LOW PRESSURE OVER THE NORTHERN PLAINS WILL
CONTINUE TO SPREAD LIGHT RAIN SHOWERS INTO OUR AREA...MAINLY EAST
OF KBIL...TONIGHT AND TUESDAY. AREAS OF MVFR CONDITIONS WILL
IMPACT KMLS AND KBHK. TO THE WEST INCLUDING KLVM...SCATTERED
SHOWERS AND TSTMS ARE DIMINISHING AND SHOULD END BY 06Z. VFR WILL
PREVAIL IN THIS AREA THOUGH TUESDAY...BUT CANNOT DISCOUNT
LOCALIZED FOG NEAR KLVM LATE TONIGHT. EAST WINDS WILL INCREASE ON
TUESDAY WITH GUSTS OF 15-25 KTS BY AFTERNOON. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 044/066 042/068 049/073 050/075 048/077 051/077 051/073
41/B 12/T 33/T 43/T 32/T 22/T 22/T
LVM 037/069 039/066 042/067 041/068 040/075 041/076 042/070
31/B 14/T 44/T 43/T 32/T 22/T 22/T
HDN 045/069 044/070 049/077 050/078 048/079 051/080 051/076
51/B 12/T 33/T 33/T 32/T 22/T 22/T
MLS 045/058 043/066 048/073 053/075 051/078 055/078 054/076
43/W 21/B 21/N 33/T 32/T 23/T 33/T
4BQ 044/060 043/066 048/074 052/076 050/079 053/080 052/077
64/W 21/B 21/N 23/T 32/T 23/T 33/T
BHK 041/050 040/060 045/067 050/070 050/075 053/073 052/073
+6/W 22/T 11/N 33/T 33/T 33/T 34/T
SHR 040/061 038/067 046/076 049/075 046/078 048/079 048/075
61/B 12/T 32/T 33/T 32/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
944 AM MDT SUN MAY 19 2013
.UPDATE...
DEEP UPPER TROUGH REMAINS OVER THE REGION TODAY AND IS BECOMING
NEGATIVELY TILTED. THE UPPER TROUGH IS ALSO CLOSING OFF AN UPPER.
CIRCULATION AROUND THE UPPER LOW IS WRAPPING PRECIPITATION INTO
OUR AREA FROM BAKER TO LIVINGSTON THIS MORNING. HAVE INCREASED
POPS ACROSS SOUTH CENTRAL AND SOUTHEAST MONTANA THIS MORNING TO
100`S AS VERY MOIST FLOW MOVING INTO THE AREA. UPPER AIR SOUNDINGS
AT GGW AND UNR SHOW PW`S NEAR 1 INCH FOR TODAY. STRONG UPPER LEVEL
FORCING ALONG WITH ISENTROPIC LIFT/BAND OF FRONTOGENESIS AND DEEP
UPSLOPE FLOW...WILL ALL COMBINE TO BRING PERIODS OF LIGHT TO
MODERATED RAINFALL ACROSS THE FORECAST AREA THE ENTIRE DAY. THE
MAJOR CONCERN CONTINUES TO BE THE BURN SCARS FROM LAST YEAR AND
WILL KEEP CURRENT FLASH FLOOD WATCH FOR THESE AREAS GOING. NO
OTHER CHANGES TO THE FORECAST FOR THIS MORNING. RICHMOND
&&
.SHORT TERM...VALID FOR TDY AND MON...
CONFIDENCE IN A SIGNIFICANT RAINFALL EVENT ACROSS MUCH OF THE AREA
OVER THE NEXT 36 TO 48 HOURS IS GROWING. ANOTHER ONE TO TWO INCHES
OF RAIN LOOKS LIKELY...AND REALISTICALLY-SPEAKING TOTALS MAY BE IN
THE 2 TO 4 INCH RANGE FROM THE BIG HORN MOUNTAINS NORTHEAST ACROSS
THE PLAINS OF FAR SOUTH CENTRAL AND MUCH OF SOUTHEASTERN MT.
AT 09 UTC...REGIONAL RADAR AND MOISTURE CHANNEL IMAGES SUGGEST THE
MID-LEVEL TROUGH IS BEGINNING TO CLOSE OFF OVER WESTERN SD...WHICH
IS WHAT ALL OF THE 00 UTC MODEL SOLUTIONS SUGGESTED WILL HAPPEN BY
MID MORNING. THOSE 00 UTC MODELS ALSO HAD A NOTABLE WESTWARD SHIFT
IN THE PLACEMENT OF THE MID- AND UPPER-LEVEL LOW WHICH IS EXPECTED
TO WOBBLE ACROSS THE DAKOTAS TODAY AND MON...AND THAT PUTS MUCH OF
THE AREA WITHIN FAVORABLE DYNAMIC FORCING FOR RAINFALL. THE 00 UTC
ECMWF ALSO MADE A SHIFT WEST AND NORTH...BUT IT IS NOT AS WET OVER
MT AS THE REST OF THE GUIDANCE HEADING INTO MON...SO WE CAUTIOUSLY
WEIGHTED THE FORECAST AWAY FROM THAT IDEA FOR NOW SINCE IT ENDS UP
AS A BIT OF AN OUTLIER.
TODAY...SHOWERS WHICH FORMED ACROSS SOUTH CENTRAL MT OVERNIGHT ARE
EXPECTED TO CONTINUE AND FILL IN FURTHER. MEANWHILE...BOTH FORCING
AND MOISTURE ADVECTION WILL INCREASE ALOFT OVER SOUTHEASTERN MT BY
MIDDAY AS THE 700-HPA LOW DEEPENS OVER WESTERN SD. CONVECTION SEEN
IN THE DAKOTAS EARLY THIS MORNING SHOULD ROTATE WESTWARD...AND NEW
PRECIPITATION WILL LIKELY FILL IN AS WELL. THE 00 UTC GFS AND GFS-
FED RAP RUNS ARE ESPECIALLY STRONG WITH THE 700-HPA LOW...AND THEY
ARE ALSO THE FARTHEST NORTHWEST MODEL SOLUTIONS WITH THIS FEATURE.
THAT IS NOT OUT OF THE QUESTION...AND IF IT ENDS UP BEING RIGHT WE
MAY EVEN HAVE OUTRIGHT HEAVY STRATIFORM RAIN BY AFTERNOON ACROSS A
GOOD PART OF THE AREA. NEEDLESS TO SAY...CATEGORICAL POPS NEAR 100
PERCENT ARE JUSTIFIED NEARLY EVERYWHERE TODAY.
TONIGHT...MOISTURE-LADEN AND DYNAMIC FORCING WILL CONTINUE FEEDING
PRECIPITATION OVER THE AREA...ESPECIALLY OVER SOUTHEASTERN MT NEAR
THE MID-LEVEL LOW...AND WHERE THE 500-300 HPA Q-VECTOR CONVERGENCE
IS STRONGEST. POPS NEAR 100 PERCENT THUS CONTINUE FOR MOST PLACES.
THE 03 UTC SREF HAS A 70 TO 90 PERCENT PROBABILITY FOR AT LEAST AN
INCH OF RAIN IN SOUTHEASTERN MT OVERNIGHT...WHICH IS NOTEWORTHY OF
AN ENSEMBLE SOLUTION. PRECIPITABLE WATER VALUES ARE EXPECTED TO BE
FROM 0.80 INCHES IN SOUTH CENTRAL MT TO AN INCH OR MORE ACROSS THE
SOUTHEASTERN PART OF MT...AND GIVEN 12 HOURS OF FORCING...RAINFALL
WILL PROBABLY BE AT LEAST NEAR THOSE VALUES IN MOST AREAS. OUR QPF
WAS INCREASED SIGNIFICANTLY OVER PREVIOUS FORECASTS...BUT IT STILL
LAGS THE 00 UTC MULTI-MODEL CONSENSUS IN SOME CASES...AND SO THERE
IS A CHANCE WE ARE STILL UNDERPLAYING TOTAL RAINFALL. THAT WILL BE
PARTICULARLY TRUE IF THE 00 UTC ECMWF ENDS UP BEING AN INCORRECTLY
DRY OUTLIER.
MON...MOISTURE SHOULD CONTINUE WRAPPING AROUND THE MID- AND UPPER-
LEVEL CIRCULATION AND BACK INTO SOUTHEASTERN MT THROUGH THE DAY. A
DRYING TREND COULD BEGIN IN SOUTH CENTRAL MT BY AFTERNOON...MAINLY
AWAY FROM UPSLOPE AREAS...AS FORECAST SOUNDINGS IN LOCALES SUCH AS
BILLINGS START SHOWING LESS SATURATION AFTER 18 UTC. IT COULD TAKE
UNTIL VERY LATE MON NIGHT OR EVEN INTO TUE THOUGH BEFORE DRYING IS
ABLE TO TAKE HOLD IN SOUTHEASTERN MT. LARGE LOWS LIKE THIS ONE ARE
OFTEN SLOWER TO MOVE THAN EXPECTED INITIALLY. THE RIDGE THAT FORMS
AT 500 HPA TO THE NORTH OF THE LOW IN SOUTHERN CANADA WILL PLAY A
BIG ROLE IN ITS SPEED SINCE IT WILL BE A BLOCKING MECHANISM.
SO...IN SUMMARY...THIS LOOKS INCREASINGLY LIKE A BIG RAIN EVENT IN
MUCH OF THE AREA. WHILE CONVECTIVE ELEMENTS WILL BE LESS LIKELY AS
WE GO FORWARD...THERE IS STILL ENSEMBLE SUPPORT FOR THREE AND SIX-
HOUR RAIN TOTALS OF A HALF INCH OR MORE IN MANY AREAS. WE CHOSE TO
ISSUE A FLASH FLOOD WATCH FOR THE BURN SCAR AREAS OF SOUTH CENTRAL
AND SOUTHEASTERN MT THROUGH 12 UTC TUE SINCE AMOUNTS LIKE THAT MAY
BE ENOUGH TO CAUSE ISSUES IN SOME OF THOSE AREAS. SCHULTZ
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
CONTINUE TO SLOW THE TRANSITION TO DRIER WEATHER. MODELS
STRUGGLING WITH THE EXIT SPEED OF THE DEEP UPPER LOW CURRENTLY
PROVIDING GENEROUS PRECIPITATION TO THE FORECAST AREA. MODELS WERE
FAIRLY CONSISTENT NOW IN VERY SLOWLY SLIDING THE UPPER LOW
EASTWARD. DIFFERENCES CENTER ON THE POSITION OF THE BLOCKING HIGH
IN SOUTHERN CANADA. THE GFS WAS FARTHER SOUTH AND THUS CLEARS THE
FORECAST AREA WITH DYNAMICS SOONER THAN THE ECMWF ON TUESDAY. THE
ECMWF HAS THE BLOCKING HIGH FARTHER NORTH AND THUS LINGERS ENERGY
INTO TUESDAY OVER THE SOUTHEAST. WILL KEEP SCATTERED POPS IN THE
EAST ON TUESDAY WHILE THE WEST SHOULD EFFECTIVELY DRY OUT. LOWERED
HIGH TEMPERATURES AS THE UPPER RIDGE WAS NOT NEARLY AS AMPLIFIED
ON 00Z RUNS.
THE NEXT UPSTREAM...AND VERY DEEP...UPPER LOW OVER THE NORTHWEST
SLIDES INTO PLACE AND TURNS THE FLOW SOUTHERLY OVER SOUTHERN
MONTANA AND NORTHERN WYOMING BY WEDNESDAY. THIS WILL ESTABLISH LOW
LEVEL EASTERLY FLOW WITH LOWER SURFACE PRESSURES OVER THE GREAT
BASIN ALLOWING DEWPOINTS TO STAY UP. MODELS CONTINUE TO BACK OFF
WITH THE DRIER AIR ALOFT AND LINGER 700MB MOISTURE INTO FRIDAY NOW
AS THE UPPER LOW INCHES EASTWARD. WILL KEEP POPS MENTIONED FROM
WEDNESDAY ONWARD WITH THE BEST CHANCE OVER THE WEST CLOSER TOO THE
UPPER LOW AND UNDER THE INFLUENCE OF SLIGHTLY COOLER AIR ALOFT.
THE ECMWF WAS A LITTLE FASTER IN KICKING THE UPPER LOW NORTHEAST
ON FRIDAY BUT BOTH MODELS HAVE THE STRONGEST DYNAMICS HEADED NORTH
OF THE FORECAST AREA...SO DID NOT GO THAT HIGH WITH POPS FRIDAY
AND SATURDAY. OVERALL...COOLED THINGS DOWN A LITTLE BIT THROUGHOUT
THE EXTENDED WITH A LESS AMPLIFIED RIDGE NOW ADVERTISED BETWEEN
THE TWO DEEP UPPER LOWS. TWH
&&
.AVIATION...
ACTIVE WEATHER WILL CONTINUE TODAY AS AN AREA OF LOW PRESSURE
ALOFT MOVES SLOWLY THROUGH THE REGION. EXPECT SHOWERS AND ISOLATED
THUNDERSTORMS TODAY...WITH AREAS OF MVFR TO IFR CONDITIONS. SOME
FOG IS ALSO POSSIBLE EARLY THIS MORNING DUE TO THE ABUNDANT
SURFACE MOISTURE IN PLACE. FOG MAY REDUCE FLIGHT CONDITIONS TO IFR
OR LOWER IF IT DEVELOPS...AND THIS IS MOST LIKELY TO OCCUR IS IN
EASTERN PARTS NEAR KMLS AND KBHK. MOUNTAINS WILL BE OBSCURED. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY MON TUE WED THU FRI SAT
-------------------------------------------------------
BIL 058 049/061 045/069 046/069 049/072 049/074 050/075
+/T +8/R 41/B 12/T 42/T 22/T 22/T
LVM 056 046/058 038/065 040/067 040/067 041/069 042/069
9/T 86/R 41/B 14/T 44/T 43/T 33/T
HDN 059 050/061 045/070 044/071 049/074 048/077 050/077
+/T ++/R 51/E 12/T 32/T 22/T 22/T
MLS 059 051/060 046/064 046/068 050/071 050/074 052/076
+/T ++/R 53/W 12/T 22/T 22/T 22/T
4BQ 059 049/057 044/062 044/068 048/072 049/074 051/076
+/T ++/R 64/W 22/T 22/T 22/T 22/T
BHK 059 049/057 043/058 044/064 047/067 048/070 051/074
+/T ++/R 84/W 22/T 22/T 22/T 22/T
SHR 055 047/056 042/062 040/069 046/072 046/075 048/075
+/T ++/R 52/W 12/T 32/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE MONDAY NIGHT FOR
ZONES 29>31-36>38-57-58.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
920 AM MDT SUN MAY 19 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
THE LOW PRESSURE CENTERS ARE CLOSING OFF AND BEGINNING TO STACK
OVER THE WESTERN DAKOTAS WHERE THE FOCUS OF PRECIPITATION IS THIS
MORNING. A BIT OF DRY SLOTTING THROUGH THE CENTRAL COUNTIES OF
NORTHEAST MONTANA PROMPTED SOME ADJUSTMENTS TO POPS/QPF AND WX FOR
TODAY. EXPECT WIND TO PICK UP AS THE SURFACE LOW RETROGRADES BACK
TOWARDS OUR CWA. AS IT DOES THE INVERTED SURFACE TROUGH NUDGES
INTO NEMONT BRINGING HEAVIER RAIN AND SOME THUNDERSTORMS BY LATE
AFTERNOON. ADJUSTED WIND BASED ON OBSERVATIONS AND THE LATEST
GUIDANCE. TEMPERATURES LOOK GOOD SO NO ADJUSTMENTS THERE. SCT
PREVIOUS DISCUSSION...
TODAY THROUGH MONDAY NIGHT...UPPER LEVEL TROUGH WILL CONTINUE TO
PROVIDE UNSETTLED WEATHER CONDITIONS FOR NE MT. A SURFACE LOW
PRESSURE SYSTEM WILL CONTINUE TO SIT AND SPIN AS IT BECOMES
VERTICALLY STACKED OVER EASTERN SOUTH DAKOTA BY MONDAY. THIS LOW
PRESSURE WILL CONTINUE TO PUMP EASTERLY SURFACE FLOW INTO THE CWA
WHICH WITH COMBINED WITH LOBES OF UPPER LEVEL SHORTWAVE ENERGY
SWIRLING AROUND THE TROUGH...WILL HELP PROVIDE THE SUPPORT FOR A
CONTINUATION OF VERY STEADY RAIN SHOWERS. LOOKING AT NAM BUFR
FORECAST SOUNDINGS...DO NOTE THAT LI IS NEAR 0 IN SOME LOCATIONS
DURING SUNDAY AFTERNOON WITH TOTAL TOTALS HOVERING AROUND 50.
GIVEN THE CONVECTIVE NATURE OF THE PULSES OF SHOWER ACTIVITY THAT
HAVE OCCURRED THE PAST COUPLE OF DAYS HOWEVER...AM NOT COMPLETELY
SOLD ON THE IDEA THAT THUNDER WILL NOT AT ALL BE A POSSIBILITY.
WITH THE STEADY RAINS...DO FEEL EMBEDDED THUNDER IS A POSSIBILITY
AND SO KEPT IN A SLIGHT MENTION OF IT. SOUNDINGS ARE ALSO SHOWING
AN INCH OR MORE PRECIPITABLE WATER THROUGH THIS PERIOD AND SO
THERE IS CERTAINLY PLENTY OF MOISTURE IN THE VERTICAL TO WORK
WITH.
MODEL GUIDANCE HAS BEEN FAIRLY CONSISTENT WITH THE STEADY
RAINS AFFECTING MUCH OF THE CWA THROUGH MONDAY NIGHT...BUT
PREFERRED THE ECMWF AND THE HRRR SOLUTIONS GIVEN EXCELLENT RUN TO
RUN CONTINUITY. WILL EXPECT THE HEAVIEST RAINFALL AMOUNTS IN THE
SOUTHEASTERN ZONES CLOSER TO THE SURFACE LOW...BUT ISOLATED HIGHER
RAINFALL TOTALS MAY OCCUR WHERE THUNDER AND/OR THE STEADIEST
RAINFALL DOES OCCUR. THAT WILL LARGELY DEPEND UPON MESOSCALE
DETAILS THAT ARE COMPLEX AND DIFFICULT TO PINPOINT AT THIS TIME.
CERTAINLY THERE WILL LIKELY BE A WIDESPREAD WETTING RAIN ACROSS
THE CWA THROUGH MONDAY NIGHT...BUT ISOLATED LOCATIONS MAY PICK UP
AN ADDITIONAL ONE TO TWO INCHES OF RAINFALL.
TUESDAY...THE RAIN SLOWLY EXITS THE FORECAST REGION FROM WEST TO
EAST. HAVE DROPPED OFF POPS ACCORDINGLY DURING THE DAY ON TUESDAY
AND ESPECIALLY TUESDAY NIGHT. WITH LITTLE CHANGE IN THE FORECAST
850MB TEMPERATURES...WILL NOT EXPECT MUCH IN THE WAY OF SWINGS.
EXPECTING SEASONAL CONDITIONS THROUGH THE ENTIRE SHORT TERM
PERIOD...OR PERHAPS SLIGHTLY BELOW AVERAGE WITH THE LARGE TROUGH
IN PLACE. MALIAWCO
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE EXTENDED PERIOD CONTINUES WITH UPPER LOWS TO OUR WEST AND EAST
AND CONFUSED FLOW OVER NORTHEAST MONTANA. THIS WILL CONTINUE UNTIL
FRIDAY WHEN THE UPPER LOW IN THE PACIFIC NORTHWEST SHIFTS CLOSER
TO NORTHEAST MONTANA. THIS WILL ENHANCE THE POSSIBILITY OF
THUNDERSTORMS OVER THE WEEKEND.
TEMPERATURES WILL CONTINUE AROUND NORMAL WITH HIGHS HOVERING
AROUND 70 AND LOWS IN THE UPPER 40S TO LOWER 50S THROUGH THE PERIOD.
MODEL TRENDS SHOW A FAIRLY SMOOTH RUN TO RUN PERFORMANCE WHICH
ASSISTS WITH A HIGH CONFIDENCE. DID NOT GO TOO HIGH FOR POPS OVER
THE UPCOMING WEEKEND SINCE THERE IS A HINT OF RETROGRESSION
STARTING TO SHOW UP WITH FALLING HEIGHTS IN MOST ENSEMBLES OVER
THE NORTHEAST PACIFIC. THIS COULD LEAD TO THE UPPER LOW SINKING
FURTHER SOUTH AND WEST KEEPING NORTHEAST MONTANA DRIER. OVERALL
ENSEMBLES ARE FAIRLY GOOD SINCE WE ARE IN A CLIMATOLOGICAL NORMAL
PATTERN. RMOP ARE FAIRLY GOOD WITH THE LARGE SCALE FEATURES FOR
THE EXTENDED PERIOD. THEREFORE MODERATE TO GOOD CONFIDENCE IN THE
PERIOD FROM TUESDAY NIGHT THROUGH FRIDAY WITH SOME LOWER
CONFIDENCE IN THE WEEKEND PATTERN. PROTON
&&
.AVIATION...
MVFR. MODELS HAVE BEEN A LITTLE LOW ON CEILING HEIGHTS AT ALL
LOCATIONS FOR PAST 48 HOURS AND LOOK TO CONTINUE THE TREND FOR THE
NEXT 24 HOURS. WILL MAINTAIN MVFR AT MOST LOCATIONS WITH LOW VFR
FOR GLASGOW THROUGH THE PERIOD. COOLER TEMPERATURES ALOFT WILL
CONTINUE THE SHOWERY CONDITIONS THROUGH THE PERIOD. PROTON
&&
.HYDROLOGY...
THE NEXT FEW DAYS WILL BE RATHER WET AS AN UPPER-LEVEL TROUGH
AFFECTS THE AREA. SEVERAL DISTURBANCES ASSOCIATED WITH THIS
TROUGH WILL PASS THROUGH WHICH WILL KEEP CHANCES FOR RAIN WITH
SOME THUNDERSTORMS THROUGH EARLY NEXT WEEK. MODEL GUIDANCE DEPICTS
HIGH AMOUNTS OF MOISTURE WITH THIS SYSTEM. AT THIS POINT THE
ENVIRONMENT LOOKS FAVORABLE FOR SLOW-MOVING STORMS WITH HIGHER
PRECIPITATION IN LOCALIZED AREAS.
MOST OF THE BASINS IN NORTHEAST MONTANA WILL BE ABLE TO
ACCOMMODATE THIS AMOUNT OF MOISTURE...AT LEAST EARLY ON IN THE
EVENT. THERE IS SOME CONCERN FOR RAPIDLY RISING STREAMS...FIELD
FLOODING AND LOCALIZED FLOODING IN TOWNS AS THE EVENT PERSISTS.
SOME MINOR FLOODING MAY BECOME AN ISSUE... ESPECIALLY FOR THE
AREAS FROM GLASGOW TO CIRCLE AND EASTWARD INTO NORTH DAKOTA WHERE
THE POTENTIAL FOR STRONGER THUNDERSTORMS IS HIGHER.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GLASGOW MT
352 AM MDT SUN MAY 19 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
TODAY THROUGH MONDAY NIGHT...UPPER LEVEL TROUGH WILL CONTINUE TO
PROVIDE UNSETTLED WEATHER CONDITIONS FOR NE MT. A SURFACE LOW
PRESSURE SYSTEM WILL CONTINUE TO SIT AND SPIN AS IT BECOMES
VERTICALLY STACKED OVER EASTERN SOUTH DAKOTA BY MONDAY. THIS LOW
PRESSURE WILL CONTINUE TO PUMP EASTERLY SURFACE FLOW INTO THE CWA
WHICH WITH COMBINED WITH LOBES OF UPPER LEVEL SHORTWAVE ENERGY
SWIRLING AROUND THE TROUGH...WILL HELP PROVIDE THE SUPPORT FOR A
CONTINUATION OF VERY STEADY RAIN SHOWERS. LOOKING AT NAM BUFR
FORECAST SOUNDINGS...DO NOTE THAT LI IS NEAR 0 IN SOME LOCATIONS
DURING SUNDAY AFTERNOON WITH TOTAL TOTALS HOVERING AROUND 50.
GIVEN THE CONVECTIVE NATURE OF THE PULSES OF SHOWER ACTIVITY THAT
HAVE OCCURRED THE PAST COUPLE OF DAYS HOWEVER...AM NOT COMPLETELY
SOLD ON THE IDEA THAT THUNDER WILL NOT AT ALL BE A POSSIBILITY.
WITH THE STEADY RAINS...DO FEEL EMBEDDED THUNDER IS A POSSIBILITY
AND SO KEPT IN A SLIGHT MENTION OF IT. SOUNDINGS ARE ALSO SHOWING
AN INCH OR MORE PRECIPITABLE WATER THROUGH THIS PERIOD AND SO
THERE IS CERTAINLY PLENTY OF MOISTURE IN THE VERTICAL TO WORK
WITH.
MODEL GUIDANCE HAS BEEN FAIRLY CONSISTENT WITH THE STEADY
RAINS AFFECTING MUCH OF THE CWA THROUGH MONDAY NIGHT...BUT
PREFERRED THE ECMWF AND THE HRRR SOLUTIONS GIVEN EXCELLENT RUN TO
RUN CONTINUITY. WILL EXPECT THE HEAVIEST RAINFALL AMOUNTS IN THE
SOUTHEASTERN ZONES CLOSER TO THE SURFACE LOW...BUT ISOLATED HIGHER
RAINFALL TOTALS MAY OCCUR WHERE THUNDER AND/OR THE STEADIEST
RAINFALL DOES OCCUR. THAT WILL LARGELY DEPEND UPON MESOSCALE
DETAILS THAT ARE COMPLEX AND DIFFICULT TO PINPOINT AT THIS TIME.
CERTAINLY THERE WILL LIKELY BE A WIDESPREAD WETTING RAIN ACROSS
THE CWA THROUGH MONDAY NIGHT...BUT ISOLATED LOCATIONS MAY PICK UP
AN ADDITIONAL ONE TO TWO INCHES OF RAINFALL.
TUESDAY...THE RAIN SLOWLY EXITS THE FORECAST REGION FROM WEST TO
EAST. HAVE DROPPED OFF POPS ACCORDINGLY DURING THE DAY ON TUESDAY
AND ESPECIALLY TUESDAY NIGHT. WITH LITTLE CHANGE IN THE FORECAST
850MB TEMPERATURES...WILL NOT EXPECT MUCH IN THE WAY OF SWINGS.
EXPECTING SEASONAL CONDITIONS THROUGH THE ENTIRE SHORT TERM
PERIOD...OR PERHAPS SLIGHTLY BELOW AVERAGE WITH THE LARGE TROUGH
IN PLACE. MALIAWCO
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE EXTENDED PERIOD CONTINUES WITH UPPER LOWS TO OUR WEST AND EAST
AND CONFUSED FLOW OVER NORTHEAST MONTANA. THIS WILL CONTINUE UNTIL
FRIDAY WHEN THE UPPER LOW IN THE PACIFIC NORTHWEST SHIFTS CLOSER
TO NORTHEAST MONTANA. THIS WILL ENHANCE THE POSSIBILITY OF
THUNDERSTORMS OVER THE WEEKEND.
TEMPERATURES WILL CONTINUE AROUND NORMAL WITH HIGHS HOVERING
AROUND 70 AND LOWS IN THE UPPER 40S TO LOWER 50S THROUGH THE PERIOD.
MODEL TRENDS SHOW A FAIRLY SMOOTH RUN TO RUN PERFORMANCE WHICH
ASSISTS WITH A HIGH CONFIDENCE. DID NOT GO TOO HIGH FOR POPS OVER
THE UPCOMING WEEKEND SINCE THERE IS A HINT OF RETROGRESSION
STARTING TO SHOW UP WITH FALLING HEIGHTS IN MOST ENSEMBLES OVER
THE NORTHEAST PACIFIC. THIS COULD LEAD TO THE UPPER LOW SINKING
FURTHER SOUTH AND WEST KEEPING NORTHEAST MONTANA DRIER. OVERALL
ENSEMBLES ARE FAIRLY GOOD SINCE WE ARE IN A CLIMATOLOGICAL NORMAL
PATTERN. RMOP ARE FAIRLY GOOD WITH THE LARGE SCALE FEATURES FOR
THE EXTENDED PERIOD. THEREFORE MODERATE TO GOOD CONFIDENCE IN THE
PERIOD FROM TUESDAY NIGHT THROUGH FRIDAY WITH SOME LOWER
CONFIDENCE IN THE WEEKEND PATTERN. PROTON
&&
.AVIATION...
MVFR. MODELS HAVE BEEN A LITTLE LOW ON CEILING HEIGHTS AT ALL
LOCATIONS FOR PAST 48 HOURS AND LOOK TO CONTINUE THE TREND FOR THE
NEXT 24 HOURS. WILL MAINTAIN MVFR AT MOST LOCATIONS WITH LOW VFR
FOR GLASGOW THROUGH THE PERIOD. COOLER TEMPERATURES ALOFT WILL
CONTINUE THE SHOWERY CONDITIONS THROUGH THE PERIOD. PROTON
&&
.HYDROLOGY...
THE NEXT FEW DAYS WILL BE RATHER WET AS AN UPPER-LEVEL TROUGH
AFFECTS THE AREA. SEVERAL DISTURBANCES ASSOCIATED WITH THIS TROUGH
WILL PASS THROUGH WHICH WILL KEEP CHANCES FOR RAIN WITH SOME
THUNDERSTORMS THROUGH EARLY NEXT WEEK. MODEL GUIDANCE DEPICTS HIGH
AMOUNTS OF MOISTURE WITH THIS SYSTEM. AT THIS POINT THE
ENVIRONMENT LOOKS FAVORABLE FOR SLOW-MOVING STORMS WITH HIGHER
PRECIPITATION IN LOCALIZED AREAS.
MOST OF THE BASINS IN NORTHEAST MONTANA WILL BE ABLE TO ACCOMMODATE
THIS AMOUNT OF MOISTURE... AT LEAST EARLY ON IN THE EVENT. THERE IS
SOME CONCERN FOR RAPIDLY RISING STREAMS...FIELD FLOODING AND
LOCALIZED FLOODING IN TOWNS AS THE EVENT PERSISTS. SOME MINOR
FLOODING MAY BECOME AN ISSUE... ESPECIALLY FOR THE AREAS FROM
GLASGOW TO CIRLE AND EASTWARD INTO NORTH DAKOTA WHERE THE POTENTIAL
FOR STRONGER THUNDERSTORMS IS HIGHER.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BILLINGS MT
350 AM MDT SUN MAY 19 2013
.SHORT TERM...VALID FOR TDY AND MON...
CONFIDENCE IN A SIGNIFICANT RAINFALL EVENT ACROSS MUCH OF THE AREA
OVER THE NEXT 36 TO 48 HOURS IS GROWING. ANOTHER ONE TO TWO INCHES
OF RAIN LOOKS LIKELY...AND REALISTICALLY-SPEAKING TOTALS MAY BE IN
THE 2 TO 4 INCH RANGE FROM THE BIG HORN MOUNTAINS NORTHEAST ACROSS
THE PLAINS OF FAR SOUTH CENTRAL AND MUCH OF SOUTHEASTERN MT.
AT 09 UTC...REGIONAL RADAR AND MOISTURE CHANNEL IMAGES SUGGEST THE
MID-LEVEL TROUGH IS BEGINNING TO CLOSE OFF OVER WESTERN SD...WHICH
IS WHAT ALL OF THE 00 UTC MODEL SOLUTIONS SUGGESTED WILL HAPPEN BY
MID MORNING. THOSE 00 UTC MODELS ALSO HAD A NOTABLE WESTWARD SHIFT
IN THE PLACEMENT OF THE MID- AND UPPER-LEVEL LOW WHICH IS EXPECTED
TO WOBBLE ACROSS THE DAKOTAS TODAY AND MON...AND THAT PUTS MUCH OF
THE AREA WITHIN FAVORABLE DYNAMIC FORCING FOR RAINFALL. THE 00 UTC
ECMWF ALSO MADE A SHIFT WEST AND NORTH...BUT IT IS NOT AS WET OVER
MT AS THE REST OF THE GUIDANCE HEADING INTO MON...SO WE CAUTIOUSLY
WEIGHTED THE FORECAST AWAY FROM THAT IDEA FOR NOW SINCE IT ENDS UP
AS A BIT OF AN OUTLIER.
TODAY...SHOWERS WHICH FORMED ACROSS SOUTH CENTRAL MT OVERNIGHT ARE
EXPECTED TO CONTINUE AND FILL IN FURTHER. MEANWHILE...BOTH FORCING
AND MOISTURE ADVECTION WILL INCREASE ALOFT OVER SOUTHEASTERN MT BY
MIDDAY AS THE 700-HPA LOW DEEPENS OVER WESTERN SD. CONVECTION SEEN
IN THE DAKOTAS EARLY THIS MORNING SHOULD ROTATE WESTWARD...AND NEW
PRECIPITATION WILL LIKELY FILL IN AS WELL. THE 00 UTC GFS AND GFS-
FED RAP RUNS ARE ESPECIALLY STRONG WITH THE 700-HPA LOW...AND THEY
ARE ALSO THE FARTHEST NORTHWEST MODEL SOLUTIONS WITH THIS FEATURE.
THAT IS NOT OUT OF THE QUESTION...AND IF IT ENDS UP BEING RIGHT WE
MAY EVEN HAVE OUTRIGHT HEAVY STRATIFORM RAIN BY AFTERNOON ACROSS A
GOOD PART OF THE AREA. NEEDLESS TO SAY...CATEGORICAL POPS NEAR 100
PERCENT ARE JUSTIFIED NEARLY EVERYWHERE TODAY.
TONIGHT...MOISTURE-LADEN AND DYNAMIC FORCING WILL CONTINUE FEEDING
PRECIPITATION OVER THE AREA...ESPECIALLY OVER SOUTHEASTERN MT NEAR
THE MID-LEVEL LOW...AND WHERE THE 500-300 HPA Q-VECTOR CONVERGENCE
IS STRONGEST. POPS NEAR 100 PERCENT THUS CONTINUE FOR MOST PLACES.
THE 03 UTC SREF HAS A 70 TO 90 PERCENT PROBABILITY FOR AT LEAST AN
INCH OF RAIN IN SOUTHEASTERN MT OVERNIGHT...WHICH IS NOTEWORTHY OF
AN ENSEMBLE SOLUTION. PRECIPITABLE WATER VALUES ARE EXPECTED TO BE
FROM 0.80 INCHES IN SOUTH CENTRAL MT TO AN INCH OR MORE ACROSS THE
SOUTHEASTERN PART OF MT...AND GIVEN 12 HOURS OF FORCING...RAINFALL
WILL PROBABLY BE AT LEAST NEAR THOSE VALUES IN MOST AREAS. OUR QPF
WAS INCREASED SIGNIFICANTLY OVER PREVIOUS FORECASTS...BUT IT STILL
LAGS THE 00 UTC MULTI-MODEL CONSENSUS IN SOME CASES...AND SO THERE
IS A CHANCE WE ARE STILL UNDERPLAYING TOTAL RAINFALL. THAT WILL BE
PARTICULARLY TRUE IF THE 00 UTC ECMWF ENDS UP BEING AN INCORRECTLY
DRY OUTLIER.
MON...MOISTURE SHOULD CONTINUE WRAPPING AROUND THE MID- AND UPPER-
LEVEL CIRCULATION AND BACK INTO SOUTHEASTERN MT THROUGH THE DAY. A
DRYING TREND COULD BEGIN IN SOUTH CENTRAL MT BY AFTERNOON...MAINLY
AWAY FROM UPSLOPE AREAS...AS FORECAST SOUNDINGS IN LOCALES SUCH AS
BILLINGS START SHOWING LESS SATURATION AFTER 18 UTC. IT COULD TAKE
UNTIL VERY LATE MON NIGHT OR EVEN INTO TUE THOUGH BEFORE DRYING IS
ABLE TO TAKE HOLD IN SOUTHEASTERN MT. LARGE LOWS LIKE THIS ONE ARE
OFTEN SLOWER TO MOVE THAN EXPECTED INITIALLY. THE RIDGE THAT FORMS
AT 500 HPA TO THE NORTH OF THE LOW IN SOUTHERN CANADA WILL PLAY A
BIG ROLE IN ITS SPEED SINCE IT WILL BE A BLOCKING MECHANISM.
SO...IN SUMMARY...THIS LOOKS INCREASINGLY LIKE A BIG RAIN EVENT IN
MUCH OF THE AREA. WHILE CONVECTIVE ELEMENTS WILL BE LESS LIKELY AS
WE GO FORWARD...THERE IS STILL ENSEMBLE SUPPORT FOR THREE AND SIX-
HOUR RAIN TOTALS OF A HALF INCH OR MORE IN MANY AREAS. WE CHOSE TO
ISSUE A FLASH FLOOD WATCH FOR THE BURN SCAR AREAS OF SOUTH CENTRAL
AND SOUTHEASTERN MT THROUGH 12 UTC TUE SINCE AMOUNTS LIKE THAT MAY
BE ENOUGH TO CAUSE ISSUES IN SOME OF THOSE AREAS. SCHULTZ
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
CONTINUE TO SLOW THE TRANSITION TO DRIER WEATHER. MODELS
STRUGGLING WITH THE EXIT SPEED OF THE DEEP UPPER LOW CURRENTLY
PROVIDING GENEROUS PRECIPITATION TO THE FORECAST AREA. MODELS WERE
FAIRLY CONSISTENT NOW IN VERY SLOWLY SLIDING THE UPPER LOW
EASTWARD. DIFFERENCES CENTER ON THE POSITION OF THE BLOCKING HIGH
IN SOUTHERN CANADA. THE GFS WAS FARTHER SOUTH AND THUS CLEARS THE
FORECAST AREA WITH DYNAMICS SOONER THAN THE ECMWF ON TUESDAY. THE
ECMWF HAS THE BLOCKING HIGH FARTHER NORTH AND THUS LINGERS ENERGY
INTO TUESDAY OVER THE SOUTHEAST. WILL KEEP SCATTERED POPS IN THE
EAST ON TUESDAY WHILE THE WEST SHOULD EFFECTIVELY DRY OUT. LOWERED
HIGH TEMPERATURES AS THE UPPER RIDGE WAS NOT NEARLY AS AMPLIFIED
ON 00Z RUNS.
THE NEXT UPSTREAM...AND VERY DEEP...UPPER LOW OVER THE NORTHWEST
SLIDES INTO PLACE AND TURNS THE FLOW SOUTHERLY OVER SOUTHERN
MONTANA AND NORTHERN WYOMING BY WEDNESDAY. THIS WILL ESTABLISH LOW
LEVEL EASTERLY FLOW WITH LOWER SURFACE PRESSURES OVER THE GREAT
BASIN ALLOWING DEWPOINTS TO STAY UP. MODELS CONTINUE TO BACK OFF
WITH THE DRIER AIR ALOFT AND LINGER 700MB MOISTURE INTO FRIDAY NOW
AS THE UPPER LOW INCHES EASTWARD. WILL KEEP POPS MENTIONED FROM
WEDNESDAY ONWARD WITH THE BEST CHANCE OVER THE WEST CLOSER TOO THE
UPPER LOW AND UNDER THE INFLUENCE OF SLIGHTLY COOLER AIR ALOFT.
THE ECMWF WAS A LITTLE FASTER IN KICKING THE UPPER LOW NORTHEAST
ON FRIDAY BUT BOTH MODELS HAVE THE STRONGEST DYNAMICS HEADED NORTH
OF THE FORECAST AREA...SO DID NOT GO THAT HIGH WITH POPS FRIDAY
AND SATURDAY. OVERALL...COOLED THINGS DOWN A LITTLE BIT THROUGHOUT
THE EXTENDED WITH A LESS AMPLIFIED RIDGE NOW ADVERTISED BETWEEN
THE TWO DEEP UPPER LOWS. TWH
&&
.AVIATION...
ACTIVE WEATHER WILL CONTINUE TODAY AS AN AREA OF LOW PRESSURE
ALOFT MOVES SLOWLY THROUGH THE REGION. EXPECT SHOWERS AND ISOLATED
THUNDERSTORMS TODAY...WITH AREAS OF MVFR TO IFR CONDITIONS. SOME
FOG IS ALSO POSSIBLE EARLY THIS MORNING DUE TO THE ABUNDANT
SURFACE MOISTURE IN PLACE. FOG MAY REDUCE FLIGHT CONDITIONS TO IFR
OR LOWER IF IT DEVELOPS...AND THIS IS MOST LIKELY TO OCCUR IS IN
EASTERN PARTS NEAR KMLS AND KBHK. MOUNTAINS WILL BE OBSCURED. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY MON TUE WED THU FRI SAT
-------------------------------------------------------
BIL 058 049/061 045/069 046/069 049/072 049/074 050/075
+/T +8/R 41/B 12/T 42/T 22/T 22/T
LVM 056 046/058 038/065 040/067 040/067 041/069 042/069
7/T 86/R 41/B 14/T 44/T 43/T 33/T
HDN 059 050/061 045/070 044/071 049/074 048/077 050/077
+/T ++/R 51/E 12/T 32/T 22/T 22/T
MLS 059 051/060 046/064 046/068 050/071 050/074 052/076
+/T ++/R 53/W 12/T 22/T 22/T 22/T
4BQ 059 049/057 044/062 044/068 048/072 049/074 051/076
+/T ++/R 64/W 22/T 22/T 22/T 22/T
BHK 059 049/057 043/058 044/064 047/067 048/070 051/074
+/T ++/R 84/W 22/T 22/T 22/T 22/T
SHR 055 047/056 042/062 040/069 046/072 046/075 048/075
+/T ++/R 52/W 12/T 32/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE MONDAY NIGHT FOR
ZONES 29>31-36>38-57-58.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1055 PM MDT Sat May 18 2013
...UPDATE TO AVIATION...
.DISCUSSION...
Update forthcoming. Showers and isolated weak thunderstorms continue
across the area. No reports of severe criteria with only very small
hail reported with some storms. HRRR analysis and latest RUC model
indicating a lessening of shower activity after 06z and, have
lowered pops a bit for that period. Remainder of forecast looks on
track with unsettled showery pattern continuing through Sunday.
Emanuel
&&
.AVIATION...
UPDATED 0500Z.
Unsettled weather continues for the next 24 hours as rain showers
are expected to remain in the area for the entire TAF period. An
isolated thunderstorm is still possible...however not expecting any
long duration impacts so no VCTS or TSRA in the TAFs. Ceilings and
visibilities should remain VFR but brief MVFR/IFR conditions are
possible near any precipitation areas. Suk
&&
.PREV DISCUSSION...Issued 257 PM MDT Sat May 18 2013
Tonight through Monday...Scattered showers and isolated
thunderstorms are developing this afternoon as instability
increases with an upper-level trough pushing through the Northern
Rockies. With the cooler air aloft, some of these showers and
thunderstorms may contain graupel. On Sunday, the upper-level low
associated with the trough will further deepen as it moves into
eastern Montana, which will shift the surface flow more northerly.
As abundant moisture wraps into this system, upslope precipitation
will develop and become steadier and more widespread, especially
during the afternoon hours. There are still some differences in
the models regarding where the heaviest precipitation will be
located, however confidence is increasing that the best precip
chances will be for areas along and east of I-15 as well as areas
along the Rocky Mountain Front. Cooler, Canadian air will also
keep snow levels lower on Sunday with snow levels between 7000 and
8000 feet. Over southwest Montana, precipitation will be
widespread but off and on through the period. The system will move
further east on Monday with drier air pushing in west to east.
High temperatures will remain below average through Sunday, then
rise to near seasonal averages on Monday. MLV
Monday Night through Saturday...Extended forecast period begins with
mostly quiet conditions as the upper level system that will cross
Montana this weekend will be moving into the Upper Midwest states
and a well-amplified high pressure ridge begins to settle in over
ern Montana and the Dakotas. Meanwhile, a second upper level trof
is forecast to swing through western Canada and form a closed low
pressure center over the PACNW coast by Tues eve. With the large
ridge remaining anchored thru the middle of the country, the Pacific
low essentially becomes stationary, drifting along the coast and
occasionally moving inland during the latter half of next week.
Minor shortwaves and accompanying moisture rotating around the
central low will bring intermittent periods of showers and isolated
thunderstorms each day from Wed onward. Forecast models are in
decent agreement that most parts of central/southwest MT will see
rain during this time, but precip amounts still look to be generally
light (0.10-0.15 inch or less) over the plains and valleys.
Rainfall totals are slightly higher (0.20-0.50 inch) over the
melting snowfields of the Rocky Mtn Front and Little Belt Mtns,
which gives concern for increased streamflows in creeks/rivers in
those areas. Persistent southerly flow aloft will allow
temperatures to stay close to typical seasonal values with highs in
the mid-60s to the low 70s each day, though that will be modified
quite a bit by a fair amount of cloud cover and the timing of the
shortwave passages.
Waranauskas
&&
.HYDROLOGY...
Two upper level trofs, one moving through our region this weekend
and the other becoming stationary over the PACNW coast for much of
next week, will bring increased chances for rainfall over the next
several days. Though cooler temperatures will reduce snowmelt
slightly, the primary concern is that rain on the melting snowpack
will cause enhanced rises in stream/river levels. Most area rivers
are currently well below flood stage but a handful of sites are near
or approaching bankfull, so rainfall totals and river stage
forecasts will be closely monitored for significant changes and
impacts. Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 44 61 44 66 / 60 70 60 40
CTB 42 62 42 67 / 60 50 40 30
HLN 44 62 45 68 / 60 50 50 30
BZN 41 60 41 66 / 80 60 50 30
WEY 36 53 35 59 / 70 60 50 40
DLN 38 59 40 66 / 60 50 40 20
HVR 47 68 46 71 / 80 80 70 70
LWT 44 57 43 62 / 80 80 70 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
101 PM CDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 1254 PM CDT SUN MAY 19 2013
AS A COLD UPPER LEVEL AREA OF LOW PRESSURE SLOWLY MOVES EAST
NORTHEAST OVER THE FORECAST THIS AFTERNOON...SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE. A RESISTANT
AREA OF SHOWERS AND STORMS CONTINUES TO FOCUS OVER KEITH AND
ARTHUR COUNTIES...NEAR THE CENTER OF THE UPPER LEVEL LOW. RADAR
ESTIMATES ARE ABOUT THREE QUARTERS OF AN INCH PER HOUR...WITH
OBSERVATIONS VERIFYING THIS. HAVE HAD A COUPLE OF REPORTS OF
WATER BEGINNING TO POND...AND WILL GO AHEAD AND ISSUE AN URBAN AND
SMALL STREAM FLOOD ADVISORY THROUGH THE AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CDT SUN MAY 19 2013
AN UPPER LEVEL COLD POOL CURRENTLY ACROSS ERN COLO WILL SPARK
SCATTERED SHOWERS AND THUNDERSTORMS TODAY AS IT DRIFTS NORTH
THROUGH THE FCST AREA. SOUTHERLY LOW LEVEL WINDS AND MOISTURE
ADVECTION ALONG AND EAST OF HIGHWAY 183 LOOK SUFFICIENT FOR A FEW
SEVERE STORMS CAPABLE OF LARGE HAIL. SIMILARLY THE COLD POOL FCST
TO LIFT NORTH THROUGH THE FCST TODAY COULD PRODUCE A FEW STORMS
WITH MARGINAL SEVERE HAIL WEST OF HIGHWAY 183.
IT LOOKS LIKE HIGHS IN THE LOWER 60S WEST TO MID 70S EAST. TEMPS IN
THE EAST REALLY DEPEND ON THE ABILITY OF A WARM SECTOR TO OPEN UP.
BASED ON CURRENT CONDITIONS...THERE IS A CHANCE TEMPS COULD WARM UP
A BIT MORE IN THE EAST AND THIS WOULD INCREASE THE THREAT OF SEVERE
WEATHER. OVERALL.. THE RUC LOOKED LIKE THE BEST FIT FOR THE JOB AS
IT SHOWS ELEVATED INSTABILITY PERSISTING THROUGHOUT THE DAY AND INTO
THIS EVENING. THE H700 LOW IN ALL MODELS SHOULD DEEPEN ACROSS THE
DAKOTAS TODAY AND TONIGHT WITH THE H500 MB COLD POOL LAGGING SOUTH
ACROSS NEB. THIS WILL LIFT SFC LOW ACROSS WRN KS NORTH THROUGH ERN
NEB. THIS SUPPORTS SCATTERED SHOWERS AND THUNDERSTORMS BUT NOT MUCH
MORE AS THE BETTER FOCUS IS ACROSS THE NORTH...PRESUMABLY. THERE ARE
QUITE A RANGE OF MODEL RAINFALL FORECASTS FOR THIS EVENT. THE
OFFICIAL FORECAST FOLLOWS LESSER QPF AMOUNTS GIVEN THAT THE BEST
FORCING IS NORTH OF THE FORECAST AREA.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 353 AM CDT SUN MAY 19 2013
ON MONDAY MORNING...THE LOW PRESSURE SYSTEM IS EXPECTED TO BE
STACKED AND CENTERED OVER CENTRAL SD WITH RELATIVELY DRY AIR OVER
CENTRAL NEBRASKA. HOWEVER...AS THE DRIER AIR PUSHES EAST...SHOWERS
AND POSSIBLY A FEW THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON
UNDER THE MAY SUN. TEMPS WILL STRUGGLE TO RISE TOMORROW...REMAINING
IN THE 60S ACROSS MOST OF THE AREA IN THE AFTERNOON. AFTER THE
DIURNALLY DRIVEN SHOWERS TAPER OFF DURING THE EVENING HOURS...SOME
HIGHER THETA-E AIR WILL WRAP AROUND THE LOW TO THE NORTH AND
THROUGH THE AREA IN THE MID LEVELS MONDAY NIGHT...HELPING TO KEEP
PRECIPITATION CHANCES IN THE FORECAST. THE UPPER LOW WILL SLOWLY
WOBBLE EASTWARD TUESDAY AND WEDNESDAY...WITH SHOWER COVERAGE
DIMINISHING EACH DAY. AN UPPER RIDGE WILL MOVE EAST INTO THE
REGION ON THURSDAY. CHANCES FOR PRECIPITATION WILL COME AGAIN
TOWARD THE END OF THE WEEK AS SOUTHWESTERLY FLOW ALOFT RETURNS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1247 PM CDT SUN MAY 19 2013
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH TONIGHT
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...AS A COLD UPPER LEVEL
LOW PRESSURE SYSTEMS SLOWLY MOVES EAST ACROSS THE AREA. AREAS OF
MVFR ARE EXPECTED WITHIN AREAS RECEIVING SHOWERS. OTHERWISE SFC
WINDS WILL BE NORTHWEST AT 5 TO 15 KTS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TAYLOR
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1253 PM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CDT SUN MAY 19 2013
AN UPPER LEVEL COLD POOL CURRENTLY ACROSS ERN COLO WILL SPARK
SCATTERED SHOWERS AND THUNDERSTORMS TODAY AS IT DRIFTS NORTH
THROUGH THE FCST AREA. SOUTHERLY LOW LEVEL WINDS AND MOISTURE
ADVECTION ALONG AND EAST OF HIGHWAY 183 LOOK SUFFICIENT FOR A FEW
SEVERE STORMS CAPABLE OF LARGE HAIL. SIMILARLY THE COLD POOL FCST
TO LIFT NORTH THROUGH THE FCST TODAY COULD PRODUCE A FEW STORMS
WITH MARGINAL SEVERE HAIL WEST OF HIGHWAY 183.
IT LOOKS LIKE HIGHS IN THE LOWER 60S WEST TO MID 70S EAST. TEMPS IN
THE EAST REALLY DEPEND ON THE ABILITY OF A WARM SECTOR TO OPEN UP.
BASED ON CURRENT CONDITIONS...THERE IS A CHANCE TEMPS COULD WARM UP
A BIT MORE IN THE EAST AND THIS WOULD INCREASE THE THREAT OF SEVERE
WEATHER. OVERALL.. THE RUC LOOKED LIKE THE BEST FIT FOR THE JOB AS
IT SHOWS ELEVATED INSTABILITY PERSISTING THROUGHOUT THE DAY AND INTO
THIS EVENING. THE H700 LOW IN ALL MODELS SHOULD DEEPEN ACROSS THE
DAKOTAS TODAY AND TONIGHT WITH THE H500 MB COLD POOL LAGGING SOUTH
ACROSS NEB. THIS WILL LIFT SFC LOW ACROSS WRN KS NORTH THROUGH ERN
NEB. THIS SUPPORTS SCATTERED SHOWERS AND THUNDERSTORMS BUT NOT MUCH
MORE AS THE BETTER FOCUS IS ACROSS THE NORTH...PRESUMABLY. THERE ARE
QUITE A RANGE OF MODEL RAINFALL FORECASTS FOR THIS EVENT. THE
OFFICIAL FORECAST FOLLOWS LESSER QPF AMOUNTS GIVEN THAT THE BEST
FORCING IS NORTH OF THE FORECAST AREA.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 353 AM CDT SUN MAY 19 2013
ON MONDAY MORNING...THE LOW PRESSURE SYSTEM IS EXPECTED TO BE
STACKED AND CENTERED OVER CENTRAL SD WITH RELATIVELY DRY AIR OVER
CENTRAL NEBRASKA. HOWEVER...AS THE DRIER AIR PUSHES EAST...SHOWERS
AND POSSIBLY A FEW THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON
UNDER THE MAY SUN. TEMPS WILL STRUGGLE TO RISE TOMORROW...REMAINING
IN THE 60S ACROSS MOST OF THE AREA IN THE AFTERNOON. AFTER THE
DIURNALLY DRIVEN SHOWERS TAPER OFF DURING THE EVENING HOURS...SOME
HIGHER THETA-E AIR WILL WRAP AROUND THE LOW TO THE NORTH AND
THROUGH THE AREA IN THE MID LEVELS MONDAY NIGHT...HELPING TO KEEP
PRECIPITATION CHANCES IN THE FORECAST. THE UPPER LOW WILL SLOWLY
WOBBLE EASTWARD TUESDAY AND WEDNESDAY...WITH SHOWER COVERAGE
DIMINISHING EACH DAY. AN UPPER RIDGE WILL MOVE EAST INTO THE
REGION ON THURSDAY. CHANCES FOR PRECIPITATION WILL COME AGAIN
TOWARD THE END OF THE WEEK AS SOUTHWESTERLY FLOW ALOFT RETURNS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1247 PM CDT SUN MAY 19 2013
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH TONIGHT
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...AS A COLD UPPER LEVEL
LOW PRESSURE SYSTEMS SLOWLY MOVES EAST ACROSS THE AREA. AREAS OF
MVFR ARE EXPECTED WITHIN AREAS RECEIVING SHOWERS. OTHERWISE SFC
WINDS WILL BE NORTHWEST AT 5 TO 15 KTS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1229 PM CDT SUN MAY 19 2013
.AVIATION...18Z TAFS FOR KOFK...KLNK AND KOMA.
SCATTERED THUNDERSTORMS COULD AFFECT ALL EASTERN NEBRASKA TAF
SITES THROUGH THE EVENING. KOFK WILL SEE SCATTERED THUNDERSTORMS
THROUGH ABOUT 21Z BEFORE A BREAK IN THE ACTION THERE. AT KLNK AND
KOMA...MOST STORMS WILL REMAIN WEST OF THE TAF SITE THROUGH 00Z
BEFORE A BAND OF STORMS SWEEPS THROUGH. WHILE STORMS COULD POP AT
JUST ABOUT ANY TIME DURING THE AFTERNOON AND EVENING...TAFS WERE
WRITTEN TO INCLUDE A 2 TO 4 HOUR WINDOW OF MOST LIKELY STORM
ACTIVITY. EACH ROUND OF STORMS WILL BRING AT LEAST MVFR
CONDITIONS...BUT IFR CIGS/VSBYS CAN BE EXPECTED WITHIN
THUNDERSTORM AREAS. MOST OF THE ACTIVITY SHOULD BE MOVING EAST OF
TAF SITES BY 04-06Z TIME FRAME...BUT MORE SHOWERS WILL LIKELY
FILTER INTO KOFK FROM THE NORTHWEST AFTER 06Z. VFR CONDITIONS ARE
EXPECTED OUTSIDE OF ANY PRECIPITATION.
DERGAN
&&
.PREV DISCUSSION... /ISSUED 1132 AM CDT SUN MAY 19 2013/
UPDATE...
A COUPLE OF VORTICITY MAXIMA WERE NOTED ON SATELLITE AND RADAR LATE
THIS MORNING...ONE LIFTING NORTH INTO NORTHWEST IOWA...AND ANOTHER
MOVING NORTHEAST INTO NORTH CENTRAL NEBRASKA. EASTERN VORT WAS
TAKING SHOWERS AND ISOLATED THUNDERSTORMS WITH IT...SO EXPECT A FEW
MORE HOURS OF PESKY SHOWERS IN WEST CENTRAL IOWA. TO THE
WEST...SHOWERS AND THUNDERSTORMS WERE BEGINNING TO FIRE ALONG A
SPOKE OF VORTICITY AROUND WESTERN CENTER...BUBBLING UP IN OUR FAR
WESTERN CWA. NOT EXPECTING ANYTHING MAJOR WITH THESE STORMS AS
INSTABILITY HAS REMAINED IN CHECK DUE TO LINGERING MORNING RAINS.
HOWEVER INSTABILITY IS EXPECTED TO INCREASE MARKEDLY ACROSS A GOOD
PART OF EASTERN NEBRASKA AND WESTERN IOWA THIS AFTERNOON AS
SOUTHERLY FLOW DRAWS MOISTENING LOW LEVEL AIR NORTH AND MID LEVEL
TEMPERATURES COOL WITH APPROACH OF UPPER TROUGH/LOW. MID LEVEL LAPSE
RATES GREATER THAN 8 C/KM ARE EXPECTED. RAP CAPE FORECASTS SUGGEST
SURFACE BASED VALUES WILL APPROACH 2500 J/KG OVER THE SOUTHERN HALF
OF OUR CWA WHERE SUNSHINE IS MOST LIKELY AND SOUTH OF WARM FRONTAL
BOUNDARY SLOWLY LIFTING TOWARD OR JUST NORTH OF INTERSTATE 80 BY MID
AFTERNOON. SHEAR PROFILES WILL BE WEAKENING WITH TIME WITH APPROACH
OF UPPER/SURFACE LOWS...BUT 40 TO 50KT OF 0-6KM BULK SHEAR IS STILL
EXPECTED ACROSS SOUTHEAST NEBRASKA THROUGH 00Z..COINCIDENT WITH
RELATIVE MAXIMUM IN CAPE FIELD. AND 0-1KM STORM-RELATIVE HELICITY
APPROACHES 120. SO AT LEAST MODERATE INSTABILITY WILL BRING A HAIL
THREAT TO MUCH OF THE SOUTHEAST HALF OF THE CWA...WHILE SHEAR
PROFILES ARE MORE FAVORABLE TO A VARIETY OF SEVERE MODES FARTHER TO
THE SOUTHEAST. WHILE TORNADO THREAT LOOKS TO BE LOWER THAN WHAT THE
MODELS SHOWED YESTERDAY...IT IS CERTAINLY NOT ZERO IN FAR SOUTHEAST
NEBRASKA.
AM EXPECTING CONTINUED DEVELOPMENT OF SCATTERED THUNDERSTORMS
THROUGH THE AFTERNOON AS BROAD ASCENT OVERSPREADS THE AREA AHEAD OF
UPPER LOW. A COUPLE OF CLUSTERS OR LINES COULD FORM FROM TIME TO
TIME IN OUR WEST OR SOUTHWEST CWA AND MOVE NORTHEAST. BUT THE BEST
SEVERE THREAT WILL COME LATER IN THE DAY...SAY AFTER 4 PM...IN
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA WHERE WARMING/MOISTENING WILL
OCCUR OUTSIDE OF CONTAMINATED AIR TO THE WEST WHERE INTERMITTENT
STORMS/CLOUDS WILL TEND TO DAMPEN THREAT OF SURFACE-BASED STORMS.
DERGAN
PREV DISCUSSION... /ISSUED 641 AM CDT SUN MAY 19 2013/
DISCUSSION...
HAVE UPDATED FORECAST FOR TEMPERATURE TRENDS AS TEMPS DIP INTO THE
LOWER 60S...AS WELL AS FOR PRECIP TRENDS. CWA IS CURRENTLY
DRY...WITH SHOWERS JUST SOUTHEAST AND JUST NORTHWEST...AND BOTH OF
THOSE AREAS WEAKENING AS SHOWERS APPROACH. THINK CWA WILL LARGELY
BE DRY THROUGH THE MORNING...THOUGH DID HEDGE WITH SLIGHT CHANCE
POPS IN THE LATE MORNING IN CASE SOME SHOWERS/ISOLATED THUNDER
SNEAK INTO THE AREA. SHOULD SEE QUICK TEMPERATURE RECOVERY THIS
MORNING WITH RELATIVELY LOW CLOUD COVER...AND WINDS WILL RETURN
OUT OF THE SOUTHEAST AS OUTFLOW FROM OVERNIGHT CONVECTION MIXES
OUT. STILL POTENTIAL FOR THUNDERSTORMS - INCLUDING SEVERE - THIS
AFTERNOON AND EVENING...PARTICULARLY IN THE SOUTHEASTERN CWA WHERE
SHEAR PROFILES ARE BETTER.
MAYES
AVIATION...
12Z TAFS FOR KOMA...KLNK...AND KOFK.
COMPLEX FORECAST AGAIN FOR THE NEXT 24 HRS REGARDING TIMING AND
LOCATION OF THUNDERSTORMS AND RAIN. MORNING SHOULD BE CLEAR OF
ACTIVITY...WITH SHOWERS AND THUNDERSTORMS INCREASING IN THE
AFTERNOON. FOR NOW...HAVE KEPT A FAIRLY GENERIC MENTION OVER A
BROAD TIME SWATH...BUT THIS IS ONE OF THOSE CASES WHERE STORMS MAY
INDEED LINGER IN VICINITY OF AIRPORTS FOR SEVERAL HOURS. TIMING OF
STORMS MAY NEED TO BE ADJUSTED THOUGH...AS SITUATION BECOMES MORE
CLEAR. STORMS WOULD HAVE POTENTIAL TO REDUCE VIS AND MAYBE
CEILINGS TO MVFR BRIEFLY...WITH GUSTY WINDS ALSO POSSIBLE.
ACTIVITY SHOULD CLEAR THROUGH DURING THE EVENING...WITH LINGERING
SHOWERS THROUGH THE NIGHT THAT ARE LESS LIKELY TO CAUSE CATEGORY
RESTRICTIONS.
MAYES
PREV DISCUSSION... /ISSUED 408 AM CDT SUN MAY 19 2013/
DISCUSSION...(TODAY THROUGH NEXT SUNDAY)
ISSUED AT 408 AM CDT SUN MAY 19 2013
THE MAIN FORECAST CONCERN DURING THIS PERIOD IS SEVERE WEATHER
POTENTIAL THIS AFTERNOON AND TONIGHT.
TO START OUT THE DAY EXPECT GENERALLY DRIER WEATHER ONCE LAST
NIGHTS CONVECTION LEAVES THE AREA IN THE NEXT COUPLE HOURS. THIS
DRY WEATHER SHOULD BE SHORT LIVED ONCE THE MAIN UPPER LOW SHIFTS
EAST INTO NEBRASKA THIS EVENING ALLOWING A SURFACE FRONT TO SHIFT
ACROSS THE AREA. SEVERE WEATHER PARAMETERS INDICATE BEST POTENTIAL
FOR SEVERE WEATHER IS ACROSS FAR SOUTHEASTERN NEBRASKA WHERE A
MODERATE RISK FOR SEVERE WEATHER EXISTS. HERE...DEEP LAYER SHEAR
VALUES PUSH 50 KNOTS ALONG WITH PLENTY OF SURFACE BASED
INSTABILITY. THE MAIN SEVERE WEATHER THREAT IN THIS AREA IS LARGE
HAIL...DAMAGING WINDS AND POSSIBLY A FEW TORNADOES. ELSEWHERE THE
SEVERE WEATHER THREAT IS LOWER...BUT STILL REMAINS. AWAY FROM THE
MODERATE RISK AREA HAIL AND WIND ARE THE PRIMARY SEVERE WEATHER
THREATS.
FOR MONDAY AND TUESDAY THE UPPER LOW LINGERS ACROSS THE AREA. WITH
DEEPER MOISTURE PROGGED OVER THE NORTHERN HALF OF THE CWA...HAVE
FAVORED HIGHER PRECIPITATION CHANCES THERE. ALSO TEMPERATURES WILL
BE COOLER WITH HIGHS IN THE 70S ON MONDAY AND GENERALLY IN THE 60S
ON TUESDAY. THEREAFTER THE COOLER WEATHER LINGERS UNTIL THE UPPER
LOW FINALLY DEPARTS ON THURSDAY AND HIGH PRESSURE IS ESTABLISHED
BY THE END OF THE WEEK.
DJP
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1132 AM CDT SUN MAY 19 2013
.UPDATE...
A COUPLE OF VORTICITY MAXIMA WERE NOTED ON SATELLITE AND RADAR LATE
THIS MORNING...ONE LIFTING NORTH INTO NORTHWEST IOWA...AND ANOTHER
MOVING NORTHEAST INTO NORTH CENTRAL NEBRASKA. EASTERN VORT WAS
TAKING SHOWERS AND ISOLATED THUNDERSTORMS WITH IT...SO EXPECT A FEW
MORE HOURS OF PESKY SHOWERS IN WEST CENTRAL IOWA. TO THE
WEST...SHOWERS AND THUNDERSTORMS WERE BEGINNING TO FIRE ALONG A
SPOKE OF VORTICITY AROUND WESTERN CENTER...BUBBLING UP IN OUR FAR
WESTERN CWA. NOT EXPECTING ANYTHING MAJOR WITH THESE STORMS AS
INSTABILITY HAS REMAINED IN CHECK DUE TO LINGERING MORNING RAINS.
HOWEVER INSTABILITY IS EXPECTED TO INCREASE MARKEDLY ACROSS A GOOD
PART OF EASTERN NEBRASKA AND WESTERN IOWA THIS AFTERNOON AS
SOUTHERLY FLOW DRAWS MOISTENING LOW LEVEL AIR NORTH AND MID LEVEL
TEMPERATURES COOL WITH APPROACH OF UPPER TROUGH/LOW. MID LEVEL LAPSE
RATES GREATER THAN 8 C/KM ARE EXPECTED. RAP CAPE FORECASTS SUGGEST
SURFACE BASED VALUES WILL APPROACH 2500 J/KG OVER THE SOUTHERN HALF
OF OUR CWA WHERE SUNSHINE IS MOST LIKELY AND SOUTH OF WARM FRONTAL
BOUNDARY SLOWLY LIFTING TOWARD OR JUST NORTH OF INTERSTATE 80 BY MID
AFTERNOON. SHEAR PROFILES WILL BE WEAKENING WITH TIME WITH APPROACH
OF UPPER/SURFACE LOWS...BUT 40 TO 50KT OF 0-6KM BULK SHEAR IS STILL
EXPECTED ACROSS SOUTHEAST NEBRASKA THROUGH 00Z..COINCIDENT WITH
RELATIVE MAXIMUM IN CAPE FIELD. AND 0-1KM STORM-RELATIVE HELICITY
APPROACHES 120. SO AT LEAST MODERATE INSTABILITY WILL BRING A HAIL
THREAT TO MUCH OF THE SOUTHEAST HALF OF THE CWA...WHILE SHEAR
PROFILES ARE MORE FAVORABLE TO A VARIETY OF SEVERE MODES FARTHER TO
THE SOUTHEAST. WHILE TORNADO THREAT LOOKS TO BE LOWER THAN WHAT THE
MODELS SHOWED YESTERDAY...IT IS CERTAINLY NOT ZERO IN FAR SOUTHEAST
NEBRASKA.
AM EXPECTING CONTINUED DEVELOPMENT OF SCATTERED THUNDERSTORMS
THROUGH THE AFTERNOON AS BROAD ASCENT OVERSPREADS THE AREA AHEAD OF
UPPER LOW. A COUPLE OF CLUSTERS OR LINES COULD FORM FROM TIME TO
TIME IN OUR WEST OR SOUTHWEST CWA AND MOVE NORTHEAST. BUT THE BEST
SEVERE THREAT WILL COME LATER IN THE DAY...SAY AFTER 4 PM...IN
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA WHERE WARMING/MOISTENING WILL
OCCUR OUTSIDE OF CONTAMINATED AIR TO THE WEST WHERE INTERMITTENT
STORMS/CLOUDS WILL TEND TO DAMPEN THREAT OF SURFACE-BASED STORMS.
DERGAN
&&
.PREV DISCUSSION... /ISSUED 641 AM CDT SUN MAY 19 2013/
DISCUSSION...
HAVE UPDATED FORECAST FOR TEMPERATURE TRENDS AS TEMPS DIP INTO THE
LOWER 60S...AS WELL AS FOR PRECIP TRENDS. CWA IS CURRENTLY
DRY...WITH SHOWERS JUST SOUTHEAST AND JUST NORTHWEST...AND BOTH OF
THOSE AREAS WEAKENING AS SHOWERS APPROACH. THINK CWA WILL LARGELY
BE DRY THROUGH THE MORNING...THOUGH DID HEDGE WITH SLIGHT CHANCE
POPS IN THE LATE MORNING IN CASE SOME SHOWERS/ISOLATED THUNDER
SNEAK INTO THE AREA. SHOULD SEE QUICK TEMPERATURE RECOVERY THIS
MORNING WITH RELATIVELY LOW CLOUD COVER...AND WINDS WILL RETURN
OUT OF THE SOUTHEAST AS OUTFLOW FROM OVERNIGHT CONVECTION MIXES
OUT. STILL POTENTIAL FOR THUNDERSTORMS - INCLUDING SEVERE - THIS
AFTERNOON AND EVENING...PARTICULARLY IN THE SOUTHEASTERN CWA WHERE
SHEAR PROFILES ARE BETTER.
MAYES
AVIATION...
12Z TAFS FOR KOMA...KLNK...AND KOFK.
COMPLEX FORECAST AGAIN FOR THE NEXT 24 HRS REGARDING TIMING AND
LOCATION OF THUNDERSTORMS AND RAIN. MORNING SHOULD BE CLEAR OF
ACTIVITY...WITH SHOWERS AND THUNDERSTORMS INCREASING IN THE
AFTERNOON. FOR NOW...HAVE KEPT A FAIRLY GENERIC MENTION OVER A
BROAD TIME SWATH...BUT THIS IS ONE OF THOSE CASES WHERE STORMS MAY
INDEED LINGER IN VICINITY OF AIRPORTS FOR SEVERAL HOURS. TIMING OF
STORMS MAY NEED TO BE ADJUSTED THOUGH...AS SITUATION BECOMES MORE
CLEAR. STORMS WOULD HAVE POTENTIAL TO REDUCE VIS AND MAYBE
CEILINGS TO MVFR BRIEFLY...WITH GUSTY WINDS ALSO POSSIBLE.
ACTIVITY SHOULD CLEAR THROUGH DURING THE EVENING...WITH LINGERING
SHOWERS THROUGH THE NIGHT THAT ARE LESS LIKELY TO CAUSE CATEGORY
RESTRICTIONS.
MAYES
PREV DISCUSSION... /ISSUED 408 AM CDT SUN MAY 19 2013/
DISCUSSION...(TODAY THROUGH NEXT SUNDAY)
ISSUED AT 408 AM CDT SUN MAY 19 2013
THE MAIN FORECAST CONCERN DURING THIS PERIOD IS SEVERE WEATHER
POTENTIAL THIS AFTERNOON AND TONIGHT.
TO START OUT THE DAY EXPECT GENERALLY DRIER WEATHER ONCE LAST
NIGHTS CONVECTION LEAVES THE AREA IN THE NEXT COUPLE HOURS. THIS
DRY WEATHER SHOULD BE SHORT LIVED ONCE THE MAIN UPPER LOW SHIFTS
EAST INTO NEBRASKA THIS EVENING ALLOWING A SURFACE FRONT TO SHIFT
ACROSS THE AREA. SEVERE WEATHER PARAMETERS INDICATE BEST POTENTIAL
FOR SEVERE WEATHER IS ACROSS FAR SOUTHEASTERN NEBRASKA WHERE A
MODERATE RISK FOR SEVERE WEATHER EXISTS. HERE...DEEP LAYER SHEAR
VALUES PUSH 50 KNOTS ALONG WITH PLENTY OF SURFACE BASED
INSTABILITY. THE MAIN SEVERE WEATHER THREAT IN THIS AREA IS LARGE
HAIL...DAMAGING WINDS AND POSSIBLY A FEW TORNADOES. ELSEWHERE THE
SEVERE WEATHER THREAT IS LOWER...BUT STILL REMAINS. AWAY FROM THE
MODERATE RISK AREA HAIL AND WIND ARE THE PRIMARY SEVERE WEATHER
THREATS.
FOR MONDAY AND TUESDAY THE UPPER LOW LINGERS ACROSS THE AREA. WITH
DEEPER MOISTURE PROGGED OVER THE NORTHERN HALF OF THE CWA...HAVE
FAVORED HIGHER PRECIPITATION CHANCES THERE. ALSO TEMPERATURES WILL
BE COOLER WITH HIGHS IN THE 70S ON MONDAY AND GENERALLY IN THE 60S
ON TUESDAY. THEREAFTER THE COOLER WEATHER LINGERS UNTIL THE UPPER
LOW FINALLY DEPARTS ON THURSDAY AND HIGH PRESSURE IS ESTABLISHED
BY THE END OF THE WEEK.
DJP
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
623 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CDT SUN MAY 19 2013
AN UPPER LEVEL COLD POOL CURRENTLY ACROSS ERN COLO WILL SPARK
SCATTERED SHOWERS AND THUNDERSTORMS TODAY AS IT DRIFTS NORTH
THROUGH THE FCST AREA. SOUTHERLY LOW LEVEL WINDS AND MOISTURE
ADVECTION ALONG AND EAST OF HIGHWAY 183 LOOK SUFFICIENT FOR A FEW
SEVERE STORMS CAPABLE OF LARGE HAIL. SIMILARLY THE COLD POOL FCST
TO LIFT NORTH THROUGH THE FCST TODAY COULD PRODUCE A FEW STORMS
WITH MARGINAL SEVERE HAIL WEST OF HIGHWAY 183.
IT LOOKS LIKE HIGHS IN THE LOWER 60S WEST TO MID 70S EAST. TEMPS IN
THE EAST REALLY DEPEND ON THE ABILITY OF A WARM SECTOR TO OPEN UP.
BASED ON CURRENT CONDITIONS...THERE IS A CHANCE TEMPS COULD WARM UP
A BIT MORE IN THE EAST AND THIS WOULD INCREASE THE THREAT OF SEVERE
WEATHER. OVERALL.. THE RUC LOOKED LIKE THE BEST FIT FOR THE JOB AS
IT SHOWS ELEVATED INSTABILITY PERSISTING THROUGHOUT THE DAY AND INTO
THIS EVENING. THE H700 LOW IN ALL MODELS SHOULD DEEPEN ACROSS THE
DAKOTAS TODAY AND TONIGHT WITH THE H500 MB COLD POOL LAGGING SOUTH
ACROSS NEB. THIS WILL LIFT SFC LOW ACROSS WRN KS NORTH THROUGH ERN
NEB. THIS SUPPORTS SCATTERED SHOWERS AND THUNDERSTORMS BUT NOT MUCH
MORE AS THE BETTER FOCUS IS ACROSS THE NORTH...PRESUMABLY. THERE ARE
QUITE A RANGE OF MODEL RAINFALL FORECASTS FOR THIS EVENT. THE
OFFICIAL FORECAST FOLLOWS LESSER QPF AMOUNTS GIVEN THAT THE BEST
FORCING IS NORTH OF THE FORECAST AREA.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 353 AM CDT SUN MAY 19 2013
ON MONDAY MORNING...THE LOW PRESSURE SYSTEM IS EXPECTED TO BE
STACKED AND CENTERED OVER CENTRAL SD WITH RELATIVELY DRY AIR OVER
CENTRAL NEBRASKA. HOWEVER...AS THE DRIER AIR PUSHES EAST...SHOWERS
AND POSSIBLY A FEW THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON
UNDER THE MAY SUN. TEMPS WILL STRUGGLE TO RISE TOMORROW...REMAINING
IN THE 60S ACROSS MOST OF THE AREA IN THE AFTERNOON. AFTER THE
DIURNALLY DRIVEN SHOWERS TAPER OFF DURING THE EVENING HOURS...SOME
HIGHER THETA-E AIR WILL WRAP AROUND THE LOW TO THE NORTH AND
THROUGH THE AREA IN THE MID LEVELS MONDAY NIGHT...HELPING TO KEEP
PRECIPITATION CHANCES IN THE FORECAST. THE UPPER LOW WILL SLOWLY
WOBBLE EASTWARD TUESDAY AND WEDNESDAY...WITH SHOWER COVERAGE
DIMINISHING EACH DAY. AN UPPER RIDGE WILL MOVE EAST INTO THE
REGION ON THURSDAY. CHANCES FOR PRECIPITATION WILL COME AGAIN
TOWARD THE END OF THE WEEK AS SOUTHWESTERLY FLOW ALOFT RETURNS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 618 AM CDT SUN MAY 19 2013
LOW CONFIDENCE FORECAST REGARDING THE START AND STOP TIMES OF THE
ROUNDS OF SHOWERS AND THUNDERSTORMS WHICH WILL LIFT NORTH THROUGH
THE FCST AREA TODAY AND TONIGHT. THE MODELS ARE SHOWING NEGATIVE
SKILL WITH THIS FEATURE SO ALL FORECASTS WILL BE BASED ON ONGOING RADAR
DATA AND ASSUME A STEADY STATE. OTHERWISE...SOME MVFR CIGS MAY
INTRUDE UPON NRN NEB ALONG AND NORTH OF HIGHWAY 20. BEST APPROACH
IS TO USE OBSERVATIONS SINCE HIGH CLOUDS ARE BLOCKING THE VIEW OF
THE LOW CLOUDS AND MODELS ARE SHOWING NO SKILL WITH THAT EITHER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
353 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CDT SUN MAY 19 2013
AN UPPER LEVEL COLD POOL CURRENTLY ACROSS ERN COLO WILL SPARK
SCATTERED SHOWERS AND THUNDERSTORMS TODAY AS IT DRIFTS NORTH
THROUGH THE FCST AREA. SOUTHERLY LOW LEVEL WINDS AND MOISTURE
ADVECTION ALONG AND EAST OF HIGHWAY 183 LOOK SUFFICIENT FOR A FEW
SEVERE STORMS CAPABLE OF LARGE HAIL. SIMILARLY THE COLD POOL FCST
TO LIFT NORTH THROUGH THE FCST TODAY COULD PRODUCE A FEW STORMS
WITH MARGINAL SEVERE HAIL WEST OF HIGHWAY 183.
IT LOOKS LIKE HIGHS IN THE LOWER 60S WEST TO MID 70S EAST. TEMPS IN
THE EAST REALLY DEPEND ON THE ABILITY OF A WARM SECTOR TO OPEN UP.
BASED ON CURRENT CONDITIONS...THERE IS A CHANCE TEMPS COULD WARM UP
A BIT MORE IN THE EAST AND THIS WOULD INCREASE THE THREAT OF SEVERE
WEATHER. OVERALL.. THE RUC LOOKED LIKE THE BEST FIT FOR THE JOB AS
IT SHOWS ELEVATED INSTABILITY PERSISTING THROUGHOUT THE DAY AND INTO
THIS EVENING. THE H700 LOW IN ALL MODELS SHOULD DEEPEN ACROSS THE
DAKOTAS TODAY AND TONIGHT WITH THE H500 MB COLD POOL LAGGING SOUTH
ACROSS NEB. THIS WILL LIFT SFC LOW ACROSS WRN KS NORTH THROUGH ERN
NEB. THIS SUPPORTS SCATTERED SHOWERS AND THUNDERSTORMS BUT NOT MUCH
MORE AS THE BETTER FOCUS IS ACROSS THE NORTH...PRESUMABLY. THERE ARE
QUITE A RANGE OF MODEL RAINFALL FORECASTS FOR THIS EVENT. THE
OFFICIAL FORECAST FOLLOWS LESSER QPF AMOUNTS GIVEN THAT THE BEST
FORCING IS NORTH OF THE FORECAST AREA.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 353 AM CDT SUN MAY 19 2013
ON MONDAY MORNING...THE LOW PRESSURE SYSTEM IS EXPECTED TO BE
STACKED AND CENTERED OVER CENTRAL SD WITH RELATIVELY DRY AIR OVER
CENTRAL NEBRASKA. HOWEVER...AS THE DRIER AIR PUSHES EAST...SHOWERS
AND POSSIBLY A FEW THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON
UNDER THE MAY SUN. TEMPS WILL STRUGGLE TO RISE TOMORROW...REMAINING
IN THE 60S ACROSS MOST OF THE AREA IN THE AFTERNOON. AFTER THE
DIURNALLY DRIVEN SHOWERS TAPER OFF DURING THE EVENING HOURS...SOME
HIGHER THETA-E AIR WILL WRAP AROUND THE LOW TO THE NORTH AND
THROUGH THE AREA IN THE MID LEVELS MONDAY NIGHT...HELPING TO KEEP
PRECIPITATION CHANCES IN THE FORECAST. THE UPPER LOW WILL SLOWLY
WOBBLE EASTWARD TUESDAY AND WEDNESDAY...WITH SHOWER COVERAGE
DIMINISHING EACH DAY. AN UPPER RIDGE WILL MOVE EAST INTO THE
REGION ON THURSDAY. CHANCES FOR PRECIPITATION WILL COME AGAIN
TOWARD THE END OF THE WEEK AS SOUTHWESTERLY FLOW ALOFT RETURNS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1215 AM CDT SUN MAY 19 2013
A FEW THUNDERSTORMS CONTINUE OVER SOUTHWEST NEBRASKA. THE STORM IN
NORTH CENTRAL NEBRASKA HAD MOVED OUT OF NORTHERN NEBRASKA.
LOW LEVEL MOISTURE REMAINING IN THE WAKE OF THE STORMS WILL BRING AT
LEAST A SLIGHT CHANCE OF PATCHY FOG AND SOME MARGINAL CEILINGS.
THUNDERSTORMS ARE AGAIN POSSIBLE SUNDAY AFTER 15Z AS A FRONT GOES
THROUGH NEBRASKA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1118 PM EDT MON MAY 20 2013
.SYNOPSIS...
A SOUTHWESTERLY FLOW OF WARM AND MORE HUMID AIR WILL CONTINUE ACROSS
THE REGION FOR MUCH OF THIS WEEK...WHILE A FRONTAL BOUNDARY ALSO
STALLS OUT ACROSS NEW YORK STATE AND SETS THE STAGE FOR INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS. THE MORE UNSETTLED CONDITIONS
WILL LAST THROUGH THURSDAY...BEFORE A COLD FRONT CROSSES THE AREA
AND USHERS IN COOLER AND DRIER WEATHER FOR THE END OF THE WEEK AND
THE MEMORIAL DAY WEEKEND.
&&
.NEAR TERM /THROUGH TUESDAY/...
BAND OF SHOWERS AND THUNDERSTORMS IS HOLDING TOGETHER ACROSS
SOUTHERN ONTARIO AND NOW WORKING TOWARD THE NIAGARA FRONTIER SO
HAVE INCREASED POPS FROM BUFFALO NORTH AND EASTWARD THIS EVENING
FOLLOWING ALONG THE LINES OF A MIX OF LATEST HRRR RUNS AND RADAR
EXTRAPOLATION. TIMING CONTINUES TO PLACE THUNDERSTORMS INTO THE
NIAGARA FRONTIER AROUND MIDNIGHT THEN SHIFTING THEM EASTWARD THROUGH
THE EARLY MORNING. 00Z BUF RAOB SHOWS AREA OF ELEVATED INSTABILITY
OVER 1000 J/KG ABOVE 700MB WHICH THE CURRENT STORMS CAN FEED OFF OF.
KBUF RADAR VELOCITY SHOWING NO WINDS HIGHER THAN 30 KNOTS AND WITH
LOW LEVEL INVERSION NOT EXPECTING ANY SEVERE IMPACTS FROM
CONVECTION. OTHERWISE BEFOREHAND THERE IS A SLIGHT CHANCE OF A POP
UP SHOWER AHEAD OF THE MAIN LINE AS THE HRRR SUGGESTS BUT KEEP
FORECAST GRIDS IN LINE WITH MAIN BAND OF PRECIP WHERE HIGHEST
CONFIDENCE LIES. TEMPS WILL REMAIN WARM AND HUMID. 850MB TEMPS IN
THE MID TEENS AND A RETURN OF BLANKETING CLOUD COVER WILL KEEP
OVERNIGHT LOW TEMPS UP IN THE LOWER TO MID 60S ACROSS THE ENTIRE
FORECAST AREA.
THE UPPER RIDGE AXIS WILL BE OVER OR TO THE EAST OF THE FORECAST
AREA ON TUESDAY AND WILL ALLOW AN INFLUX OF WARMTH AND MOISTURE WITH
DEWPOINTS SURGING TO THE UPPER 60S ACROSS WESTERN NY DURING TUESDAY
AFTERNOON. THE SUPPRESSIVE SUBSIDENCE WILL BE NEARLY ABSENT ON
TUESDAY SO CAN EXPECT CONVECTION TO DEVELOP DURING THE AFTERNOON
ALONG THE LAKE BREEZE BOUNDARIES AND THE INLAND TERRAIN. LAKE COOLED
AIR WILL PROVIDE LAKE SHADOWS WITHIN ABOUT HALF A COUNTY`S WIDTH OF
THE LAKE ERIE AND ONTARIO SHORES. WILL HAVE POPS INCREASING TO THE
LIKELY CATEGORY BY THE END OF THE DAY ON TUESDAY WITH THE CONTINUED
INFLUX OF HIGH THETA-E AIR. HIGH TEMPS ON TUESDAY SHOULD BE IN THE
LOWER TO MID 80S FOR MOST AREAS...LOWER TO MID 70S EXPECTED ACROSS
THE CLOUDIER AND POSSIBLY RAINIER TUG HILL PLATEAU AND EASTERN LAKE
ONTARIO COUNTIES.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
TUESDAY AFTERNOON/S CONVECTION IS EXPECTED TO GRADUALLY WIND DOWN
THROUGH THE EVENING HOURS WITH THE LOSS OF DIURNAL HEATING AND THE
RE-ESTABLISHMENT OF SHORTWAVE RIDGING ALOFT. SHOWERS AND
THUNDERSTORMS WILL LINGER LONGEST OVERNIGHT ACROSS THE NORTH COUNTRY
CLOSER TO THE WARM FRONTAL TROUGH. ELSEWHERE ONCE CONVECTION WINDS
DOWN EXPECT A WARM AND MUGGY NIGHT AS DEWPOINTS WILL REMAIN IN THE
LOW 60S WITH LOW TEMPS ONLY DROPPING INTO THE LOW TO MID 60S
ACCORDINGLY.
THE WARM AND HUMID AIRMASS WILL CONTINUE TO BE IN PLACE ACROSS THE
LOWER GREAT LAKES ON WEDNESDAY WITH HIGHS CLIMBING INTO THE 80S
AND SURFACE DEWPOINTS RUNNING IN THE MID 60S. THIS WILL ONCE AGAIN
PROVIDE A FAVORABLE ENVIRONMENT FOR THE DEVELOPMENT OF SHOWERS AND
THUNDERSTORMS ACROSS THE FORECAST AREA. WHILE LINGERING CLOUD COVER
MAY LIMIT INSTABILITY SOMEWHAT...THE PRESENCE OF SYNOPTIC LIFT AHEAD
OF THE APPROACHING SURFACE FRONT AND MID-LEVEL TROUGH COMBINED
SHOULD STILL ALLOW FOR THE DEVELOPMENT OF WIDESPREAD CONVECTION BY
LATE AFTERNOON. WITH A DECENT KINEMATIC FIELD FEATURING GREAT THAN
50KTS OF 0-6KM OF SHEAR INCLUDING A 40KT 850MB JET THERE IS A
POSSIBILITY THAT SOME OF THE THUNDERSTORMS COULD BECOME
SEVERE...PARTICULARLY ACROSS THE WESTERN SOUTHERN TIER WHERE
INSTABILITY SHOULD BE GREATEST. WITH A RELATIVELY UNIDIRECTIONAL
VERTICAL WIND PROFILE THE MAIN THREAT WITH ANY STRONGER
THUNDERSTORMS SHOULD BE STRONG WINDS. LARGE HAIL MAY ALSO BE A
POSSIBILITY...ONCE AGAIN PRIMARILY ACROSS THE SOUTHERN TIER WHERE THE
GREATEST INSTABILITY IS EXPECTED. ADDITIONALLY...PWATS RUNNING ABOVE
1.5 INCHES SUGGEST THAT LOCALLY HEAVY RAINS WILL ALSO BE A THREAT.
AFTER ANOTHER WARM AND MUGGY NIGHT THURSDAY NIGHT...LOOK FOR
TEMPERATURES TO START A DOWNWARD TREND ON THURSDAY AS THE
AFOREMENTIONED COLD FRONT CROSSES THE AREA. ANOTHER ROUND OF SHOWERS
WILL LIKELY ACCOMPANY THE PASSAGE OF THE SURFACE FRONT. A FEW
RUMBLES OF THUNDER MAY ALSO BE POSSIBLE...HOWEVER GREATEST
INSTABILITY WILL HAVE SHIFTED TO THE EAST OF THE FORECAST AREA BY
THIS POINT SO WILL JUST CARRY A SLIGHT CHANCE OF THUNDER.
SHOWER ACTIVITY WILL WIND DOWN THURSDAY NIGHT FROM WEST TO EAST WITH
THE PASSAGE OF THE SURFACE COLD FRONT AND UPPER LEVEL TROUGH. COLD
AIR ADVECTION BEHIND THE FRONT WILL ALLOW TEMPERATURES TO DROP INTO
THE 40S OVERNIGHT...SETTING THE STAGE FOR FAIRER...COOLER...AND DRIER
WEATHER THIS WEEKEND.
.LONG TERM /FRIDAY THROUGH SUNDAY/...
PLENTY OF SUNSHINE AND SEASONABLY COOL TEMPERATURES WILL BE THE NAME
OF THE GAME THIS WEEKEND AS HIGH PRESSURE SETTLES ACROSS THE GREAT
LAKES. FRIDAY WILL BE THE COLDEST DAY OF THE WEEK AS 850MB TEMPS
DROPPING TO AROUND 0C SHOULD ONLY YIELD HIGHS TOPPING OUT IN THE
LOWER 60S FRIDAY AND SATURDAY...NEARLY 10 DEGREES BELOW NORMAL.
LIKEWISE OVERNIGHT LOWS WILL RUN ON THE CHILLY SIDE WITH READINGS IN
THE LOWER 40S ALONG THE LAKE PLAINS WHILE AREAS FARTHER INLAND
ACROSS THE SOUTHERN TIER AND NORTH COUNTRY COULD DROP INTO MID
30S...POTENTIALLY SETTING THE STAGE FOR A FROST...PARTICULARLY ON
SATURDAY NIGHT WHEN THE SURFACE HIGH IS PROGGED TO BE OVERHEAD.
A GRADUAL REBOUND IN TEMPERATURES IS EXPECTED FOR THE LATTER HALF OF
THE WEEKEND AS THE COLDEST AIR ASSOCIATED WITH THE UPPER LEVEL
TROUGH DEPARTS THE REGION AND WARMER AIR BEGINS TO CREEP NORTH FROM
THE OHIO VALLEY ONCE AGAIN. OTHERWISE...EXPECT DRY WEATHER TO
CONTINUE THROUGH THE END OF THE WEEKEND.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
THE VARIOUS MEDIUM RANGE GUIDANCE PACKAGES ARE IN STRONG AGREEMENT
THAT GENERALLY FAIR AND SEASONABLY COOL CONDITIONS WILL BE IN PLACE
DURING THIS PERIOD...INCLUDING THE BULK OF THE MEMORIAL DAY WEEKEND.
A BROAD BASED RIDGE WILL BE POSITIONED OVER THE NATIONS MID SECTION
AND THIS WILL LEAVE TWIN TROUGHS OFF THE COASTS OF VANCOUVER AND
EASTERN QUEBEC...WHERE COOLER THAN AVERAGE TEMPERATURES ARE
EXPECTED.
A MORE DETAILED LOOK AT OUR REGION REVEALS THAT WE WILL HAVE SOME
LEFTOVER LOW CLOUDS AND LIGHT SHOWERS FRIDAY MORNING (MAINLY EAST OF
GENESEE VALLEY) IN THE WAKE OF THE DEPARTING FRONTAL SYSTEM...BUT AS
LOW LEVEL RIDGING BUILDS SOUTH ACROSS THE GREAT LAKES...OUR SKIES
WILL CLEAR OUT. H85 TEMPS WILL DROP TO AROUND 5C...SO FRIDAY WILL BE
MUCH COOLER WITH AFTERNOON TEMPS GENERALLY IN THE LOWER 60S (50S
ACROSS THE NORTH COUNTRY).
EXPANSIVE HIGH PRESSURE WILL BUILD SOUTH ACROSS THE REGION FROM
CANADA SATURDAY AND SUNDAY...WITH H85 TEMPS FORECAST TO BE IN THE
VCNTY OF 4C BOTH DAYS. THIS WILL KEEP THE AFTERNOONS COOL AND THE
NIGHTS CHILLY WITH SOME FROST POSSIBLE...MAINLY ACROSS THE SOUTHERN
TIER AND EASTERN LAKE ONTARIO REGIONS.
A PEEK AHEAD TO MEMORIAL DAY SUGGESTS THAT FAIR DRY WEATHER WILL BE
IN PLACE WITH A MODERATION IN TEMPERATURES TO NEAR SEASONAL LEVELS.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
EXPECT VFR CONDITIONS TO BRIEFLY DETERIORATE WITHIN TS AROUND
MIDNIGHT FOR KBUF/KIAG AND CLOSER TO 05Z/06Z FOR KROC AND 07Z/08Z
FOR KART. LEFT KJHW OUT OF TS BECAUSE SOUTHERN FLANK OF STORMS WILL
REMAIN TO THE NORTH OF THE AIRFIELD. SOME MVFR STRATUS IS POSSIBLE
HERE THOUGH SIMILAR TO WHAT HAPPENED LAST NIGHT.
THE UPPER AND MID LEVEL RIDGE AXES TO PASS ACROSS THE REGION AND TO
THE EAST ON TUESDAY. WILL HAVE A SLIGHTLY BETTER CHANCE OF AFTERNOON
AND EVENING CONVECTION...ALONG THE LAKE BREEZE BOUNDARIES AND OVER
THE INTERIOR OF THE FORECAST AREA.
OUTLOOK...
TUESDAY THROUGH THURSDAY...NUMEROUS SHOWERS AND THUNDERSTORMS WITH
ASSOCIATED BRIEF MVFR/IFR...OTHERWISE VFR.
FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.
SATURDAY...VFR.
&&
.MARINE...
A LINE OF SHOWERS AND THUNDERSTORMS MOVING ACROSS EASTERN MICHIGAN
AND LAKE HURON WILL SHIFT EAST THIS EVENING AND MAY PUSH ACROSS THE
LAKES ARRIVING NEAR MIDNIGHT AND SHIFTING EAST THROUGH THE EARLY
MORNING HOURS.
OTHERWISE...FOR MUCH OF THIS WEEK WINDS WILL REMAIN RELATIVELY LIGHT
AND VARIABLE IN DIRECTION DUE TO A NEARLY STATIONARY FRONTAL
BOUNDARY THAT WILL REMAIN DRAPED ACROSS THE REGION...AS WELL AS THE
DAILY DEVELOPMENT OF LAKE BREEZES. AS A RESULT...WAVE HEIGHTS SHOULD
ALSO REMAIN MINIMAL. OTHERWISE...SHOWER AND THUNDERSTORM
CHANCES WILL INCREASE MARKEDLY FOR THE TUESDAY THROUGH THURSDAY TIME
FRAME. A COLD FRONTAL PASSAGE WILL TURN WINDS TO A NORTHERLY
DIRECTION WITH AN INCREASE IN WAVE HEIGHTS... ESPECIALLY ALONG THE
SOUTH SHORE OF LAKE ONTARIO ON FRIDAY MORNING.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JJR
NEAR TERM...SMITH/WCH
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...SMITH
MARINE...SMITH
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1008 PM EDT MON MAY 20 2013
.SYNOPSIS...
UNSETTLED WEATHER PATTERN IS EXPECTED...AS A FRONTAL BOUNDARY
AMBLES ABOUT THE NORTH EAST....RESULTING IN SEVERAL ROUNDS OF
RAIN SHOWERS AND THUNDERSTORMS INTO THE MIDDLE OF THIS WEEK. HIGH
PRESSURE AND DRIER CONDITIONS RETURN FRIDAY AND CONTINUE INTO THE
WEEKEND...WITH COOLER TEMPERATURES ABOUT 5 DEGREES BELOW NORMAL.
&&
.NEAR TERM /UNTIL 8 AM TUESDAY MORNING/...
AS OF 1008 PM EDT MONDAY...LINE OF THUNDERSTORMS APPROACHING THE
WESTERN SHORE OF LAKE ONTARIO REQUIRED SEVERAL CHANGES TO THE
FORECAST FOR AFTER MIDNIGHT. LARGE STRATIFORM AREA BEHIND THE
LEADING EDGE OF THE STRONGEST CORES SUGGESTS SOME ORGANIZATION TO
THE ACTIVITY. SHORT-RANGE GUIDANCE HAS A PRETTY GOOD HANDLE ON THE
CLUSTER ESPECIALLY THE BTV12 AND THE HRRR WHICH SHOW SOME
WEAKENING TO THE SHOWERS AND STORMS AS IT MOVES EAST. SO EXPECT
SOME GRADUAL WEAKENING TO THE SHOWERS AND STORMS...THOUGH PRESENCE
OF MID- LEVEL LAPSE RATES OF 6.5-7.0 DEGREES C/KM PER 00Z BUF/ALB
RAOB SOUNDINGS AND NEGATIVE SHOWALTER INDICES MAY HELP TO SUSTAIN
OCCASIONAL LIGHTNING AS IT MOVES EAST. LEADING EDGE OF THIS
CLUSTER PROJECTED TO ENTER INTO THE SAINT LAWRENCE VALLEY AFTER
05Z. THEREFORE...HAVE MENTIONED SCATTERED TO NUMEROUS SHOWERS WITH
ISOLATED THUNDER ACROSS NORTHERN NEW YORK...AND ISOLATED TO
SCATTERED SHOWERS WITH ISOLATED THUNDER ACROSS VERMONT. HAVE ALSO
RAISED LOWS UP A COUPLE DEGREES INTO THE MID/UPPER 50S TO AROUND
60.
&&
.SHORT TERM /8 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 355 PM EDT MONDAY...STALLED FRONTAL BOUNDARY REMAINS OVER
THE NORTH COUNTRY DURING THE SHORT TERM PERIOD AND WILL BE THE
FOCUS FOR PERIODS OF RAIN AND POSSIBLE THUNDERSTORMS THROUGH
WEDNESDAY.
RAIN SHOWERS SPREAD EWD TUESDAY MORNING WITH CLOUDY SKIES AND
SOUTHERLY WINDS. GFS BEING THE OUTLIER TAKES THE BOUNDARY TO OUR
SOUTH TUESDAY AFTN...WITH MOST GUIDANCE KEEPING IT OVER THE NORTH
COUNTRY. 925MB TEMPS DEPICT THE BOUNDARY OVER THE AREA
WELL...WITH COOLER TEMPS OVER THE NEK TUESDAY AND MOST OF THE
AREA SEEING 925MB TEMPS IN THE LOW TO MID TEENS. CLOUDS CONTINUE
OVER THE AREA WITH RAIN SHOWERS AND EVEN LIFTED INDICES OF -2 FOR
AT LEAST NRN NY AND SRN HALF OF VT. SOME CAPE AND TEMP LAPSE
RATES OF 6-7 C/KM COULD HELP TRIGGER A FEW TS TUESDAY AFTN.
MOISTURE CONTINUES TO STREAM IN TO THE NORTH COUNTRY WITH GEFS
SHOWING PWATS OF 1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL
THROUGHOUT THE PERIOD.
TUESDAY NIGHT...WELL DEPICTED WARM FRONT LIFTING NORTH AS WE
CONTINUE TO BE IN THE WARM SECTOR AND 925MB TEMPS INCREASE TO
UPPER TEENS...POSSIBLY LOW 20S ON WEDNESDAY. SFC LOW MOVES INTO
SERN ONTARIO...RESULTING IN SW FLOW...BRINGING IN MORE
INSTABILITY ON WEDNESDAY. BEST CHANCES FOR TS WILL BE ON
WEDNESDAY AS LIFTED INDICES OF ZERO TO -4 SPREAD OVER THE ENTIRE
NORTH COUNTRY. TEMP LAPSE RATES GREATER THAN 7C/KM WILL ALSO MOVE
INTO THE AREA. SOME SHOWERS AND STORMS WILL LINGER INTO WEDNESDAY
NIGHT AS LOW LEVEL SW JET INCREASES IN STRENGTH AT 30-40 KTS.
TEMPS THROUGHOUT THE PERIOD WILL BE ABOVE NORMAL IN THE 70S
TUESDAY AND NEARING 80 ON WEDNESDAY. OVERNIGHT LOWS WILL BE MILD
DUE TO CLOUDS...IN THE 50S AND LOW 60S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 425 PM EDT MONDAY...
A COLD FRONT WITH SHOWERS AND THUNDERSTORMS ON THURSDAY WILL USHER
IN COOLER AND MAINLY DRY WEATHER FOR THE UPCOMING MEMORIAL DAY
WEEKEND.
CONFIDENCE FAIRLY HIGH IN THE LARGE-SCALE FEATURES AS UPPER TROF
PASSES SLOWLY ACROSS THE REGION. SOME UNCERTAINTY IN HOW THE TROF
EVOLVES AND HOW FAST IT MOVES OUT TOWARD THE END OF THE PERIOD.
ON THURSDAY THE COLD FRONT WILL MOVE SLOWLY SOUTHEAST THROUGH THE
AREA. INSTABILITY EXPECTED TO BE MARGINAL WITH CAPE VALUES AROUND
500 J/KG OR SO AND WILL DEPEND UPON CLOUD COVER. WITH LESS CLOUD
COVER VALUES COULD CLIMB NEAR 1000 J/KG ESPECIALLY SOUTH AND EAST
OF BTV. IF THE INSTABILITY MATERIALIZES AND 0-6KM BULK SHEAR
VALUES OF 30-40 KTS WILL HAVE TO WATCH FOR A FEW STRONGER STORMS.
HIGHS SHOULD BE IN THE 70S WITH 850 TEMPS AROUND +12C.
THURSDAY NIGHT WILL FEATURE A TRANSITION TO MUCH COOLER TEMPS WITH
850 TEMPS FALLING TO NEAR 0C BY 12Z FRIDAY. COULD BE SOME
LINGERING SHOWERS OVER NIGHT.
A COOL NW FLOW ON FRIDAY AND SATURDAY WITH 850 TEMPS AROUND 0 WILL
KEEP HIGH TEMPERATURES IN THE UPPER 50S TO MID 60S WITH PLENTY OF
CUMULUS CLOUDS AND EVEN A CHANCE OF A SHOWER DURING THE AFTERNOON
OR EVENING HOURS ESPECIALLY IN THE MOUNTAINS. LOW TEMPERATURES
WILL BE MAINLY 35 TO 45.
SUNDAY AND MONDAY SHOULD BE DRY AS HIGH PRESSURE MOVES INTO THE
NORTHEAST AND TEMPERATURE WILL BEGIN TO RETURN TO NORMAL WITH
HIGHS IN THE UPPER 60S TO LOW 70S AND LOWS IN THE 40S.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
THROUGH 00Z WEDNESDAY...LOW LEVEL MOISTURE REMAINS OVER THE AREA
AND THIS SHOULD LEAD TO A TREND FROM VFR CEILINGS AND VISIBILITIES
TO MVFR/IFR CEILINGS/VISIBILITIES BETWEEN 04Z AND 14Z. RAIN
SHOWERS WILL MOVE INTO SOUTHERN QUEBEC PROVINCE LATER TONIGHT AND
DROP INTO NORTHERN NEW YORK AND NORTHERN VERMONT AFTER 08Z. THE
THREAT FOR SHOWERS WILL CONTINUE THROUGHOUT THE MORNING AND
AFTERNOON HOURS ON TUESDAY. WINDS WILL BE VARIABLE UNDER 10 KNOTS.
OUTLOOK 00Z WEDNESDAY THROUGH SATURDAY...
TUE PM...WARM FRONT BRINGS MVFR SHOWERS WITH EMBEDDED TSTMS WITH
BRIEF IFR. WED- THU...SHOWERS/THUNDERSTORMS WITH PERIODS OF MVFR
CONDITIONS. THU NIGHT INTO FRI/SAT...MAINLY VFR AS DRY NWLY WINDS
DEVELOP.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...KGM
NEAR TERM...KGM/LOCONTO
SHORT TERM...KGM
LONG TERM...SISSON
AVIATION...EVENSON/SISSON
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
246 PM EDT SUN MAY 19 2013
.SYNOPSIS...
HIGH PRESSURE OFF THE NEW ENGLAND COAST AND A WEAK SYSTEM OVER THE
MID ATLANTIC WILL BRING THE CHANCE FOR SHOWERS THROUGH MONDAY. ON
MONDAY, THERE IS ALSO THE CHANCE FOR THUNDERSTORMS AS A WEAK
SURFACE TROF APPROACHES THE REGION. UNSETTLED WEATHER WILL
CONTINUE INTO THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
125 PM UPDATE...
MADE ADJUSTMENTS DOWNWARD WITH AFTERNOON HIGHS ESPECIALLY OUTSIDE
OF THE WESTERN FINGER LAKES WHERE ANY AMOUNT OF SUNSHINE LOOKS
DOUBTFUL AND WE HAVE SEEN TEMPS REALLY STRUGGLE TO CLIMB AT ALL.
WITH THAT SAID IN A NARROW AREA ALONG OUR BORDER WITH KBUF WE ARE
ALREADY INTO THE 70S SO WILL ONCE AGAIN HAVE A WIDE RANGE OF TEMPS
THIS AFTERNOON WITH 70S OVER THE FAR NORTHWEST AND 50S TO NEAR 60
OVER THE HIGHER TERRAIN OF THE SOUTHEAST.
OTHER ADJUSTMENT WAS TO LOWER POPS DRAMATICALLY AREA WIDE. OUR
FORECAST MODELS CONTINUE TO SUGGEST CHANCE POPS AND LIGHT QPF OVER
THE FAR SOUTHEAST BUT IT JUST DOESN`T APPEAR TO BE HAPPENING. ON
CLOSER INSPECTION THE MODELS ARE LIKELY OVERDOING QPF BASED ON THE
MOIST PROFILES WE ARE SEEING AND THE SOUTHEAST FLOW BEING
OVERLY ENHANCED BY TERRAIN. WITH THAT IN MIND THE TWO MAIN FOCUS
AREAS FOR PRECIP WILL BE THE NEXT HOUR OR TWO OVER THE FAR
NORTHEAST WITH OUR DEPARTING BOUNDARY FROM THIS MORNING. THEN
LATER TODAY ABUNDANT SUNSHINE OVER WESTERN NY COMBINED WITH
EXTENSIVE CLOUD COVER FARTHER EAST WILL BE ENOUGH TO SET UP A NICE
DIFFERENTIAL HEATING BOUNDARY. THIS MAY BE ENOUGH ALONG WITH ANY
LAKE BREEZE BOUNDARIES FOR SOME ISOLATED CONVECTION OVER THE
WESTERN FINGER LAKES. THE RUC DOES SHOW CAPES ABOVE 500 J/KG BUT
WITHOUT ANY SIGNIFICANT TRIGGER...KEPT IT ISOLATED AT BEST. AS
THIS DIES DOWN THIS EVENING EXPECT DRY WEATHER ACROSS THE CWA
UNTIL NEAR MIDNIGHT. BY THIS TIME I DO BELIEVE THE MODELS IN THAT
A MOIST SOUTHEAST FLOW COMBINED WITH THE RIGHT TIME OF THE DAY
(NIGHTTIME) WILL BE ENOUGH TO PRODUCE PATCHY DRIZZLE OVER THE
SOUTHEASTERN THIRD OF THE CWA. AS USUAL THE MOST LIKELY SUSPECTS
WILL BE ACROSS THE HIGHER TERRAIN. THE PREVIOUS AFD IS BELOW.
950 PM UPDATE... AN AREA OF SHOWERS STRETCHING FROM JUST
WEST OF UTICA SOUTHEAST THROUGH MADISON...OTSEGO...DELAWARE...AND
SULLIVAN COUNTIES CONTINUES TO MARCH EASTWARD. THIS AREA WILL
REMAIN THE FOCUS OF LIGHT SHOWERS AND/OR SPRINKLES THROUGH 1 PM
WITH THE REST OF THE AREA REMAINING DRY. BLENDED WITH THE PREVIOUS
FORECAST OF RAMPING POPS BACK INTO THE CHANCE RANGE LATER THIS
AFTERNOON. FAIRLY WIDE RANGE OF TEMPS TODAY WITH HIGHS BARELY
GETTING INTO THE 60S OVER MOST OF THE AREA WITH THICK CLOUD COVER.
WARMEST TEMPS WILL STILL BE IN THE NORTHWESTERN FINGER LAKES
THROUGH KSYR WHERE WE HAVE THE BEST SHOT AT SOME SUNSHINE. THE
PREVIOUS AFD IS BELOW...
RADAR SHOWS ISLD SHRA WORKING THRU C NY AND FAR
NERN PA IN ASSCTN WITH A WEAK SHRT WAVE. THIS ACVTY WILL WORK THRU
EC NY AND THE POCONOS/CATSKILLS BY MID MORNING AS MORE ISLD-SCT
SHRA ACVTY WORKS EASTWARD FROM FROM SRN ONT. THERE IS ALSO A BATCH
OF LIGHT SHRA ACROSS MUCH OF CNTRL AND SRN NJ WHICH WILL CONT TO
SLOWLY WORK NORTHEAST TODAY AND DEVELOP BACK TO THE NORTHWEST AS
PER MODEL GUIDC. NAM...GFS...EURO AND CMC ALL SHOW LIGHT PRECIP
WORKING NWRD TODAY REACHING ACRS NE PA AND INTO C NY. THE
DYNAMICAL SET UP WAS AS FOLLOWS: THE ABOVE MENTIONED UPPER LEVEL
TROF WILL MOVE SLOW ENUF OFF THE NE COAST THAT CONTINUAL SMALL
SHORT WAVES/JET STREAKS WILL INCREASE THE UPPER CONFLUENCE DURG
THE DAY TODAY. THIS WILL STRENGTHEN THE SFC HI OFF THE EAST COAST
AND INCREASE THE SERLY FLOW INTO ERN NY AND ERN PA. THE LL AGEO
WINDS SHOW THIS REALLY WELL WITH A SERLY AGEO WIND UP THRU NJ INTO
NE PA AND EC NY. THIS WILL LEAD TO A S-SERLY LLJ THAT WILL ADVECT
SIGNIFICANT LOW-LEVEL MOISTURE NWRD TODAY AND SPREAD ISLD- SCT
LIGHT RAIN SHOWERS TO THE REGION. THUS HAVE INCREASED POPS TO THE
N AND W DURG THE DAY TODAY WITH ISLD IN THE FAR NW TO CHC POPS IN
THE SERN ZONES. THE CLOUDS WILL BE THINNEST IN THE UPR FINGER
LAKES TO CENTRAL SRN TIER OF NY...HENCE MAXES WILL BE HIGHER IN
THESE AREAS VS POINTS TO THE S AND E.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR TONIGHT A SHORT WAVE TRACKS ACRS SERN CANADA AND PASSES NE OF
THE REGION. WITH THE PASSAGE OF THIS WAVE THE LOW-LEVEL FLO WILL
TURN FROM S-SERLY TO SWRLY AND DECELERATE. LIGHT SHRA SHUD WIND
DOWN FROM W-E OVERNIGHT TONIGHT SO WILL DROP POPS GRADUALLY.
FOR MONDAY...THE NAM...GFS AND CMC ALL SHOW A WEAK FRNT DROPPING
SOUTHWARD IN THE WAKE OF THE ABOVE MENTIONED CANADIAN SHORT WAVE.
THE SHIFT IN THE LL FLO TONIGHT TO MORE SWRLY WILL ALLOW FOR SIGNIFICANT
LL MOISTURE ADVECTION WITH MODELS FORECASTING DWPTS TO RISE TO AOA
60F ACROSS MUCH OF THE FORECAST AREA MON. THIS WILL OCCUR PRIOR TO
THE WK FRNTL BNDRY DROPPING SOUTHWARD MONDAY PM. HENCE THE NAM AND
GFS BOTH SHOW CAPES APPROACHING 1000 J/KG MON PM. THE UPPER LEVEL
FORCING WILL BE WEAK AS NY AND PA WILL BE JUST DOWNSTREAM FROM THE
UPPER LEVEL RDG AXIS. YSTDA/S 12Z EURO RUN NEVER DROPS THE FRNT
SOUTHWARD MONDAY AS THE SHRT WAVE TRACKING IN SERN CANADA STAYS
FARTHER N. WITH WEAK FORCING...YET DECENT CAPE AND SOME
UNCERTAINTIES WILL GO WITH GENERIC CHC/S FOR SHRA AND TSRA
FOLLOWING PREVIOUS SHIFTS AND OTHER SURROUNDING OFFICES MON INTO
MON EVE. TIMING OF THE CONVECTION WILL BE TRICKY THIS FAR OUT SO
WILL NOT BE VERY SPECIFIC YET.
FOR MONDAY NIGHT...INSTABILITY WANES TO SOME EXTENT...ESP IN THE
ERN 1/2 OF THE CWA. IN THE WEST ACRS WRN NY TO NC PA SOME CAPE
REMAINS THRU THE NIGHT. WILL DROP POPS MON NGT...WITH THE HIGHEST
LINGERING IN THE WEST AND LOWEST TO THE EAST BY TUE AM.
TUESDAY AND TUESDAY NIGHT LOOK UNSETTLED AS THE MAIN CYCLONE AND
ASSCTD UPR TROF MOVE EASTWARD AND ACCELERATE THE LL WINDS FROM THE
SW INTO NY AND PA. IN ADDTN...THERE WILL BE A LEAD SHORT WAVE THAT
WILL ENHANCE LARGE LIFTING TUE NGT. DWPTS WILL BE WELL INTO THE
60S AND WITH SIGNIFICANT MOISTURE ADVECTION...AND CAPE I SEE SHRA
AND TSRA BOTH TUE AND TUE NGT. THE 0-6 KM SHEAR LOOKS MARGINAL FOR
SVR AT THIS TIME SO NOT EXPECTING ANY SIGNIFICANT SVR WX THIS FAR
EAST. MODEL QPFS WERE RUNNING GENERALLY UNDER AN INCH SO NOT
EXPECTING ANY HYDRO ISSUES EITHER.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE EXTENDED FORECAST WILL FEATURE A DEEP UPPER LEVEL TROF OVER
THE NORTHEAST KEEPING TEMPS WELL BELOW NORMAL THROUGH THE PERIOD
AFTER A COLD FRONTAL PASSAGE ON THURSDAY.
AT THE SFC, A COLD FRONT WILL APPROACH THE REGION WEDNESDAY NIGHT
WITH FROPA ON THURSDAY. WILL CONTINUE WITH HIGH CHC/LIKELY POPS
THROUGH THIS PERIOD ALONG WITH THE CHC FOR THUNDERSTORMS. BUILDING
UPPER LEVEL TROF AND LINGERING POST FRONTAL MOISTURE WILL KEEP THE
THREAT FOR SHOWERS INTO FRIDAY. THE REMAINDER OF THE PERIOD WILL
BE DRY WITH PARTLY TO MAINLY CLEAR SKIES AS SFC HIGH PRES DROPS
SOUTH OVER THE AREA FROM CENTRAL CANADA. LOWS BOTH FRIDAY AND
SATURDAY NIGHT MAY BE COLD ENOUGH FOR FROST.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
A SOUTHEAST FLOW WILL CONTINUE OVER THE TERMINALS THROUGH DAYBREAK
MONDAY KEEPING ABUNDANT LOW LEVEL MOISTURE ACROSS THE REGION.
CURRENTLY MVFR/LOW MVFR CIGS ARE BEING OBSERVED AND THIS WILL
CONTINUE THROUGH EARLY EVENING WHEN CIGS WILL LOWER INTO THE
IFR/LOW MVFR CATEGORY. AT KITH/KBGM CIGS WILL DROP BELOW ALT MIN
OVERNIGHT WITH KRME/KELM/KAVP OCCASIONALLY FALLING INTO THE IFR
CATEGORY BETWEEN 09Z-13Z. BY MID MORNING, A SOUTHWEST FLOW WILL
ALLOW CIGS TO LIFT INTO THE MVFR/LOW VFR CATEGORY. DURING THE
AFTERNOON SCATTERED CONVECTION IS LIKELY AS A WEAK SFC TROF
APPROACHES TH REGION.
WINDS S-SE BETWEEN AROUND 5-8 KNOTS BECOMING SOUTHWEST MONDAY
MORNING.
OUTLOOK...
TUESDAY/WEDNESDAY...MVFR IN SHOWERS/THUNDERSTORMS.
THU...MVFR POSSIBLE IN SHOWERS/THUNDERSTORMS.
FRIDAY...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN/HEDEN
SHORT TERM...DJN
LONG TERM...RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
133 PM EDT SUN MAY 19 2013
.SYNOPSIS...
HIGH PRESSURE OFF THE NEW ENGLAND COAST AND A WEAK SYSTEM OVER THE
MID ATLANTIC WILL BRING THE CHANCE FOR SHOWERS THROUGH MONDAY. ON
MONDAY, THERE IS ALSO THE CHANCE FOR THUNDERSTORMS AS A WEAK
SURFACE TROF APPROACHES THE REGION. UNSETTLED WEATHER WILL
CONTINUE INTO THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
125 PM UPDATE...
MADE ADJUSTMENTS DOWNWARD WITH AFTERNOON HIGHS ESPECIALLY OUTSIDE
OF THE WESTERN FINGER LAKES WHERE ANY AMOUNT OF SUNSHINE LOOKS
DOUBTFUL AND WE HAVE SEEN TEMPS REALLY STRUGGLE TO CLIMB AT ALL.
WITH THAT SAID IN A NARROW AREA ALONG OUR BORDER WITH KBUF WE ARE
ALREADY INTO THE 70S SO WILL ONCE AGAIN HAVE A WIDE RANGE OF TEMPS
THIS AFTERNOON WITH 70S OVER THE FAR NORTHWEST AND 50S TO NEAR 60
OVER THE HIGHER TERRAIN OF THE SOUTHEAST.
OTHER ADJUSTMENT WAS TO LOWER POPS DRAMATICALLY AREA WIDE. OUR
FORECAST MODELS CONTINUE TO SUGGEST CHANCE POPS AND LIGHT QPF OVER
THE FAR SOUTHEAST BUT IT JUST DOESN`T APPEAR TO BE HAPPENING. ON
CLOSER INSPECTION THE MODELS ARE LIKELY OVERDOING QPF BASED ON THE
MOIST PROFILES WE ARE SEEING AND THE SOUTHEAST FLOW BEING
OVERLY ENHANCED BY TERRAIN. WITH THAT IN MIND THE TWO MAIN FOCUS
AREAS FOR PRECIP WILL BE THE NEXT HOUR OR TWO OVER THE FAR
NORTHEAST WITH OUR DEPARTING BOUNDARY FROM THIS MORNING. THEN
LATER TODAY ABUNDANT SUNSHINE OVER WESTERN NY COMBINED WITH
EXTENSIVE CLOUD COVER FARTHER EAST WILL BE ENOUGH TO SET UP A NICE
DIFFERENTIAL HEATING BOUNDARY. THIS MAY BE ENOUGH ALONG WITH ANY
LAKE BREEZE BOUNDARIES FOR SOME ISOLATED CONVECTION OVER THE
WESTERN FINGER LAKES. THE RUC DOES SHOW CAPES ABOVE 500 J/KG BUT
WITHOUT ANY SIGNIFICANT TRIGGER...KEPT IT ISOLATED AT BEST. AS
THIS DIES DOWN THIS EVENING EXPECT DRY WEATHER ACROSS THE CWA
UNTIL NEAR MIDNIGHT. BY THIS TIME I DO BELIEVE THE MODELS IN THAT
A MOIST SOUTHEAST FLOW COMBINED WITH THE RIGHT TIME OF THE DAY
(NIGHTTIME) WILL BE ENOUGH TO PRODUCE PATCHY DRIZZLE OVER THE
SOUTHEASTERN THIRD OF THE CWA. AS USUAL THE MOST LIKELY SUSPECTS
WILL BE ACROSS THE HIGHER TERRAIN. THE PREVIOUS AFD IS BELOW.
950 PM UPDATE... AN AREA OF SHOWERS STRETCHING FROM JUST
WEST OF UTICA SOUTHEAST THROUGH MADISON...OTSEGO...DELAWARE...AND
SULLIVAN COUNTIES CONTINUES TO MARCH EASTWARD. THIS AREA WILL
REMAIN THE FOCUS OF LIGHT SHOWERS AND/OR SPRINKLES THROUGH 1 PM
WITH THE REST OF THE AREA REMAINING DRY. BLENDED WITH THE PREVIOUS
FORECAST OF RAMPING POPS BACK INTO THE CHANCE RANGE LATER THIS
AFTERNOON. FAIRLY WIDE RANGE OF TEMPS TODAY WITH HIGHS BARELY
GETTING INTO THE 60S OVER MOST OF THE AREA WITH THICK CLOUD COVER.
WARMEST TEMPS WILL STILL BE IN THE NORTHWESTERN FINGER LAKES
THROUGH KSYR WHERE WE HAVE THE BEST SHOT AT SOME SUNSHINE. THE
PREVIOUS AFD IS BELOW...
RADAR SHOWS ISLD SHRA WORKING THRU C NY AND FAR
NERN PA IN ASSCTN WITH A WEAK SHRT WAVE. THIS ACVTY WILL WORK THRU
EC NY AND THE POCONOS/CATSKILLS BY MID MORNING AS MORE ISLD-SCT
SHRA ACVTY WORKS EASTWARD FROM FROM SRN ONT. THERE IS ALSO A BATCH
OF LIGHT SHRA ACROSS MUCH OF CNTRL AND SRN NJ WHICH WILL CONT TO
SLOWLY WORK NORTHEAST TODAY AND DEVELOP BACK TO THE NORTHWEST AS
PER MODEL GUIDC. NAM...GFS...EURO AND CMC ALL SHOW LIGHT PRECIP
WORKING NWRD TODAY REACHING ACRS NE PA AND INTO C NY. THE
DYNAMICAL SET UP WAS AS FOLLOWS: THE ABOVE MENTIONED UPPER LEVEL
TROF WILL MOVE SLOW ENUF OFF THE NE COAST THAT CONTINUAL SMALL
SHORT WAVES/JET STREAKS WILL INCREASE THE UPPER CONFLUENCE DURG
THE DAY TODAY. THIS WILL STRENGTHEN THE SFC HI OFF THE EAST COAST
AND INCREASE THE SERLY FLOW INTO ERN NY AND ERN PA. THE LL AGEO
WINDS SHOW THIS REALLY WELL WITH A SERLY AGEO WIND UP THRU NJ INTO
NE PA AND EC NY. THIS WILL LEAD TO A S-SERLY LLJ THAT WILL ADVECT
SIGNIFICANT LOW-LEVEL MOISTURE NWRD TODAY AND SPREAD ISLD- SCT
LIGHT RAIN SHOWERS TO THE REGION. THUS HAVE INCREASED POPS TO THE
N AND W DURG THE DAY TODAY WITH ISLD IN THE FAR NW TO CHC POPS IN
THE SERN ZONES. THE CLOUDS WILL BE THINNEST IN THE UPR FINGER
LAKES TO CENTRAL SRN TIER OF NY...HENCE MAXES WILL BE HIGHER IN
THESE AREAS VS POINTS TO THE S AND E.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
FOR TONIGHT A SHORT WAVE TRACKS ACRS SERN CANADA AND PASSES NE OF
THE REGION. WITH THE PASSAGE OF THIS WAVE THE LOW-LEVEL FLO WILL
TURN FROM S-SERLY TO SWRLY AND DECELERATE. LIGHT SHRA SHUD WIND
DOWN FROM W-E OVERNIGHT TONIGHT SO WILL DROP POPS GRADUALLY.
FOR MONDAY...THE NAM...GFS AND CMC ALL SHOW A WEAK FRNT DROPPING
SOUTHWARD IN THE WAKE OF THE ABOVE MENTIONED CANADIAN SHORT WAVE.
THE SHIFT IN THE LL FLO TONIGHT TO MORE SWRLY WILL ALLOW FOR SIGNIFICANT
LL MOISTURE ADVECTION WITH MODELS FORECASTING DWPTS TO RISE TO AOA
60F ACROSS MUCH OF THE FORECAST AREA MON. THIS WILL OCCUR PRIOR TO
THE WK FRNTL BNDRY DROPPING SOUTHWARD MONDAY PM. HENCE THE NAM AND
GFS BOTH SHOW CAPES APPROACHING 1000 J/KG MON PM. THE UPPER LEVEL
FORCING WILL BE WEAK AS NY AND PA WILL BE JUST DOWNSTREAM FROM THE
UPPER LEVEL RDG AXIS. YSTDA/S 12Z EURO RUN NEVER DROPS THE FRNT
SOUTHWARD MONDAY AS THE SHRT WAVE TRACKING IN SERN CANADA STAYS
FARTHER N. WITH WEAK FORCING...YET DECENT CAPE AND SOME
UNCERTAINTIES WILL GO WITH GENERIC CHC/S FOR SHRA AND TSRA
FOLLOWING PREVIOUS SHIFTS AND OTHER SURROUNDING OFFICES MON INTO
MON EVE. TIMING OF THE CONVECTION WILL BE TRICKY THIS FAR OUT SO
WILL NOT BE VERY SPECIFIC YET.
FOR MONDAY NIGHT...INSTABILITY WANES TO SOME EXTENT...ESP IN THE
ERN 1/2 OF THE CWA. IN THE WEST ACRS WRN NY TO NC PA SOME CAPE
REMAINS THRU THE NIGHT. WILL DROP POPS MON NGT...WITH THE HIGHEST
LINGERING IN THE WEST AND LOWEST TO THE EAST BY TUE AM.
TUESDAY AND TUESDAY NIGHT LOOK UNSETTLED AS THE MAIN CYCLONE AND
ASSCTD UPR TROF MOVE EASTWARD AND ACCELERATE THE LL WINDS FROM THE
SW INTO NY AND PA. IN ADDTN...THERE WILL BE A LEAD SHORT WAVE THAT
WILL ENHANCE LARGE LIFTING TUE NGT. DWPTS WILL BE WELL INTO THE
60S AND WITH SIGNIFICANT MOISTURE ADVECTION...AND CAPE I SEE SHRA
AND TSRA BOTH TUE AND TUE NGT. THE 0-6 KM SHEAR LOOKS MARGINAL FOR
SVR AT THIS TIME SO NOT EXPECTING ANY SIGNIFICANT SVR WX THIS FAR
EAST. MODEL QPFS WERE RUNNING GENERALLY UNDER AN INCH SO NOT
EXPECTING ANY HYDRO ISSUES EITHER.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
330 AM UPDATE...
BEGINNING OF EXTNDD FEATURES STALLED FRONTAL BNDRY STRETCHED FROM
THE MIDWEST INTO THE NORTHEAST. GOM WL BE WIDE OPEN AS SRLY FLOW WL
BE PREVALENT BTWN LOW TO THE WEST AND BERMUDA HIGH TO THE EAST.
AIRMASS EXPECTED TO DESTABILIZE ON WEDNESDAY, WITH POTENTIAL TO
CONTINUE THRU 12Z THURSDAY AS UL WV APPCHS FM THE WEST. THUS, HV
BUMPED POPS INTO THE LKLY RANGE ON WED ACRS NY ZONES CLOSER TO
CONVERGENCE AXIS. FROPA PROGGED TO OCCUR FRI MRNG PER GFS AND EC.
00Z EURO HAS COME MORE INTO LINE WITH GFS REGARDING UPR LVL LOW FOR
THE WEEKEND PULLING NORTH INTO THE CANADIAN MARITIMES WITH HIPRES
BUILDING IN AT THE SFC.
HV DROPPED TEMPS SLGTLY AFT 12Z FRIDAY DUE TO FROPA. MEMORIAL DAY
WEEKEND RMNS UP IN THE AIR WITH 00Z EURO INDICATING CLD TEMPS MVG
OUT OF CANADA WHILE 00Z GFS BRINGS A SFC LOW UP THE ERN SEABOARD
KEEPING COLD AIR AT BAY. 00Z GEM ALSO INDICATING A DVLPNG SFC LOW
OVR THE CAROLINAS BY 00Z SATURDAY, SIMILAR TO LATEST GFS. THUS, AM
LEANING MORE TWD WARMER GFS/GEM SOLN FOR THE END OF THE WEEK. HV
BLENDED LATEST WARM MAX TEMP FCST WITH COOLER WPC VALUES FOR INITIAL
FCST.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
12Z UPDATE...
MVFR CIGS WORKING NORTH ACROSS NY TERMINALS THIS MORNING. HIGHER
ELEVATION SITE AT KBGM SITTING AT IFR CIGS THROUGH 15Z. OTHER
TERMINALS SHOULD REMAIN MVFR TODAY. FURTHER TO THE NORTH AT KRME
AND KSYR VFR CONDITIONS WILL START OFF THE TAF PERIOD THROUGH 15Z
AND THEN BECOME MVFR THROUGH THE END OF TAF VALID TIME. LOW LEVEL
MOISTURE WILL BECOME TRAPPED UNDER THE INVERSION WITH IFR EXPECTED
AFTER 00Z AT SELECT TERMINALS.
WINDS LIGHT OUT OF THE S-SE BETWEEN 5-10KTS BECOMING MORE
SOUTHWESTERLY LATE IN THE TAF PERIOD.
OUTLOOK...
MONDAY...MVFR IN SCATTERED SHOWERS.
TUESDAY/WEDNESDAY...MVFR IN SHOWERS/THUNDERSTORMS.
THU...MVFR POSSIBLE IN SHOWERS/THUNDERSTORMS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN/HEDEN
SHORT TERM...DJN
LONG TERM...PVN
AVIATION...PVN
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1027 PM EDT MON MAY 20 2013
.SYNOPSIS...
DISTURBANCES EMBEDDED IN A MID LEVEL TROUGH WILL PIVOT OVER EASTERN
NORTH CAROLINA THROUGH TUESDAY MORNING. THE TROUGH SHOULD GRADUALLY
WEAKEN THROUGH WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 PM MONDAY...
THROUGH TONIGHT: THE MAJORITY OF THE SHOWERS HAVE DISSIPATED OR
MOVED OUT OF THE AREA THIS EVENING. A FEW ISOLATED SHOWERS HAVE
DEVELOPED DURING THE PAST COUPLE HOURS...BUT HAVE NOT BEEN HEAVY OR
LONG LASTING. THE 00Z UPPER AIR ANALYSES SHOW THE WAVE OVER CENTRAL
NC FROM 850-500 MB...WITH A SHORTWAVE TROUGH TO THE SOUTHWEST AT 250
MB. AS A PAIR OF VORTICITY MAXIMA EMBEDDED IN THE MID LEVEL TROUGH
PIVOTS OVER EASTERN NC OVERNIGHT...ADDITIONAL SHOWERS COULD DEVELOP
ACROSS THE SOUTHEAST. THE 00Z SOUNDING AT KGSO STILL YIELDS MLCAPE
AROUND 1000-1500 J/KG WITH A MOIST BOUNDARY LAYER AND RELATIVELY
DRIER AIR IN THE MID LEVELS. THE LATEST HRRR SHOWS ADDITIONAL SHOWER
ACTIVITY DEVELOPING ACROSS THE SOUTHEAST AROUND MIDNIGHT AS A MID
LEVEL DISTURBANCE MOVES OVER THE AREA. HAVE INCREASED RAIN CHANCES
IN THE EAST OVERNIGHT TO REFLECT THE POTENTIAL DEVELOPMENT.
TEMPERATURES ACROSS THE AREA ARE IN THE UPPER 60S TO LOW 70S...WITH
OVERNIGHT LOWS IN THE MID 60S EXPECTED.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...
TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.
MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.
TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 240 PM MONDAY...
FOR WEDNESDAY...WEAK SHORTWAVE RIDGING WILL BUILD OVER THE AREA...
WHILE AT THE SURFACE...THE BERMUDA HIGH WILL RIDGE WESTWARD INTO THE
CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN EVEN FURTHER DECREASE IN
PRECIP COVERAGE. HOWEVER...SUFFICIENT MOISTURE WILL STILL BE IN
PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR 1.5 INCHES OR
SO. THEREFORE...AM STILL EXPECTING TO SEE WIDELY SCATTERED TO
SCATTERED DIURNALLY DRIVEN CONVECTION...WITH THE HIGHEST CHANCES
BEING ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HIGHS ONCE
AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS IN THE
MID/UPPER 60S.
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WORK WEEK AS THE MID/UPPER LEVEL RIDGE SHIFTS
OFFSHORE AHEAD OF OUR NEXT MID/UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT. MODELS REMAIN IN GENERAL AGREEMENT WITH BRINGING THE
FRONT THROUGH THE FORECAST AREA LATE THURSDAY NIGHT/EARLY FRIDAY.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. BULK SHEAR VALUES WILL INCREASE TO
AROUND 25 KNOTS OR SO...THEREFORE BETTER STORM ORGANIZATION IS
EXPECTED...HOWEVER THE BEST UPPER LEVEL FORCING WILL PASS WELL TO
OUR NORTH. THEREFORE...EVEN THOUGH AN ISOLATED SEVERE STORM CANNOT
BE COMPLETELY RULED OUT...THE OVERALL THREAT REMAINS LOW AT THIS
TIME. WITH THE INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND
FRIDAY...TEMPS WILL MOSTLY BE IN THE LOW/MID 80S.
IT STILL APPEARS THE WEEKEND AND INTO EARLY NEXT WEEK WILL BE DRY AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT. SLIGHTLY COOLER
TEMPS ARE EXPECTED DURING THIS TIME FRAME...GENERALLY THE UPPER 70S
TO LOWER 80S...WITH OVERNIGHT LOWS IN THE 50S.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 750 PM MONDAY...
24 HOUR TAF PERIOD:
CONVECTIVE COVERAGE CONTINUES TO DIMINISH WITH LOSS OF DAYTIME
HEATING. HOWEVER AN ISOLATED TO WIDELY SCATTERED SHOWERS WILL BE
POSSIBLE THROUGH THE OVERNIGHT HOURS. MUCH LIKE LAST NIGHT...EXPECT
WIDESPREAD LIFR TO IFR CONDITIONS TO DEVELOP BETWEEN 06 TO 12Z
TUESDAY...WITH THE POTENTIAL FOR SOME FOG TO DEVELOP IN THE WEST.
CEILINGS SHOULD IMPROVE TO VFR BY 15Z TUESDAY WITH ISOLATED TO
SCATTERED SHOWERS AND STORMS DURING THE AFTERNOON AND EVENING.
LONG TERM:
LOW STRATUS AND FOG ARE EXPECTED EACH MORNING UNTIL A COLD FRONTAL
PASSAGE ON FRIDAY. DIURNAL STORMS ARE EXPECTED ON WEDNESDAY
AFTERNOON WITH THE COLD FRONTAL BRINGING A CHANCE FOR SHOWERS AND
THUNDERSTORMS THURSDAY AND THURSDAY NIGHT. CONDITIONS RETURN TO THE
AREA ON FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...ELLIS
LONG TERM...KRR
AVIATION...CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
950 PM EDT MON MAY 20 2013
.SYNOPSIS...
A SHORTWAVE TROUGH WILL CONTINUE TO WORK THROUGH THE AREA THIS
AFTERNOON BRINGING UNSETTLED WEATHER THROUGH THIS EVENING. THE
TROUGH WILL MEANDER NORTHEASTWARD TUESDAY BEFORE MORE SETTLED
WEATHER RETURNS FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 PM MONDAY...
THROUGH TONIGHT: THE MAJORITY OF THE SHOWERS HAVE DISSIPATED OR
MOVED OUT OF THE AREA THIS EVENING. A FEW ISOLATED SHOWERS HAVE
DEVELOPED DURING THE PAST COUPLE HOURS...BUT HAVE NOT BEEN HEAVY OR
LONG LASTING. THE 00Z UPPER AIR ANALYSES SHOW THE WAVE OVER CENTRAL
NC FROM 850-500 MB...WITH A SHORTWAVE TROUGH TO THE SOUTHWEST AT 250
MB. AS A PAIR OF VORTICITY MAXIMA EMBEDDED IN THE MID LEVEL TROUGH
PIVOTS OVER EASTERN NC OVERNIGHT...ADDITIONAL SHOWERS COULD DEVELOP
ACROSS THE SOUTHEAST. THE 00Z SOUNDING AT KGSO STILL YIELDS MLCAPE
AROUND 1000-1500 J/KG WITH A MOIST BOUNDARY LAYER AND RELATIVELY
DRIER AIR IN THE MID LEVELS. THE LATEST HRRR SHOWS ADDITIONAL SHOWER
ACTIVITY DEVELOPING ACROSS THE SOUTHEAST AROUND MIDNIGHT AS A MID
LEVEL DISTURBANCE MOVES OVER THE AREA. HAVE INCREASED RAIN CHANCES
IN THE EAST OVERNIGHT TO REFLECT THE POTENTIAL DEVELOPMENT.
TEMPERATURES ACROSS THE AREA ARE IN THE UPPER 60S TO LOW 70S...WITH
OVERNIGHT LOWS IN THE MID 60S EXPECTED.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...
TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.
MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.
TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 240 PM MONDAY...
FOR WEDNESDAY...WEAK SHORTWAVE RIDGING WILL BUILD OVER THE AREA...
WHILE AT THE SURFACE...THE BERMUDA HIGH WILL RIDGE WESTWARD INTO THE
CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN EVEN FURTHER DECREASE IN
PRECIP COVERAGE. HOWEVER...SUFFICIENT MOISTURE WILL STILL BE IN
PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR 1.5 INCHES OR
SO. THEREFORE...AM STILL EXPECTING TO SEE WIDELY SCATTERED TO
SCATTERED DIURNALLY DRIVEN CONVECTION...WITH THE HIGHEST CHANCES
BEING ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HIGHS ONCE
AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS IN THE
MID/UPPER 60S.
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WORK WEEK AS THE MID/UPPER LEVEL RIDGE SHIFTS
OFFSHORE AHEAD OF OUR NEXT MID/UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT. MODELS REMAIN IN GENERAL AGREEMENT WITH BRINGING THE
FRONT THROUGH THE FORECAST AREA LATE THURSDAY NIGHT/EARLY FRIDAY.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. BULK SHEAR VALUES WILL INCREASE TO
AROUND 25 KNOTS OR SO...THEREFORE BETTER STORM ORGANIZATION IS
EXPECTED...HOWEVER THE BEST UPPER LEVEL FORCING WILL PASS WELL TO
OUR NORTH. THEREFORE...EVEN THOUGH AN ISOLATED SEVERE STORM CANNOT
BE COMPLETELY RULED OUT...THE OVERALL THREAT REMAINS LOW AT THIS
TIME. WITH THE INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND
FRIDAY...TEMPS WILL MOSTLY BE IN THE LOW/MID 80S.
IT STILL APPEARS THE WEEKEND AND INTO EARLY NEXT WEEK WILL BE DRY AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT. SLIGHTLY COOLER
TEMPS ARE EXPECTED DURING THIS TIME FRAME...GENERALLY THE UPPER 70S
TO LOWER 80S...WITH OVERNIGHT LOWS IN THE 50S.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 750 PM MONDAY...
24 HOUR TAF PERIOD:
CONVECTIVE COVERAGE CONTINUES TO DIMINISH WITH LOSS OF DAYTIME
HEATING. HOWEVER AN ISOLATED TO WIDELY SCATTERED SHOWERS WILL BE
POSSIBLE THROUGH THE OVERNIGHT HOURS. MUCH LIKE LAST NIGHT...EXPECT
WIDESPREAD LIFR TO IFR CONDITIONS TO DEVELOP BETWEEN 06 TO 12Z
TUESDAY...WITH THE POTENTIAL FOR SOME FOG TO DEVELOP IN THE WEST.
CEILINGS SHOULD IMPROVE TO VFR BY 15Z TUESDAY WITH ISOLATED TO
SCATTERED SHOWERS AND STORMS DURING THE AFTERNOON AND EVENING.
LONG TERM:
LOW STRATUS AND FOG ARE EXPECTED EACH MORNING UNTIL A COLD FRONTAL
PASSAGE ON FRIDAY. DIURNAL STORMS ARE EXPECTED ON WEDNESDAY
AFTERNOON WITH THE COLD FRONTAL BRINGING A CHANCE FOR SHOWERS AND
THUNDERSTORMS THURSDAY AND THURSDAY NIGHT. CONDITIONS RETURN TO THE
AREA ON FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ELLIS
NEAR TERM...KC
SHORT TERM...ELLIS
LONG TERM...KRR
AVIATION...CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
750 PM EDT MON MAY 20 2013
.SYNOPSIS...
A SHORTWAVE TROUGH WILL CONTINUE TO WORK THROUGH THE AREA THIS
AFTERNOON BRINGING UNSETTLED WEATHER THROUGH THIS EVENING. THE
TROUGH WILL MEANDER NORTHEASTWARD TUESDAY BEFORE MORE SETTLED
WEATHER RETURNS FOR WEDNESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 215 PM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
TODAY: WIDESPREAD SHOWERS AND THUNDERSTORMS HAVE BROKEN OUT IN A
SERIES OF LINES ACROSS THE CWA THIS AFTERNOON IN ASSOCIATION WITH A
SHORTWAVE IMPULSE PASSING THROUGH SOUTHERN VA. FOR THE MOST
PART...THUNDER HAS BEEN LIMITED TO A SELECT FEW CELLS WITH HEAVY
SHOWERS BEING THE PRIMARY MODE OF CONVECTION. THERE ARE SEVERAL WEAK
BOUNDARIES THAT HAVE SET UP THIS AFTERNOON. THE FIRST HAS LIFTED
NORTHEAST OF THE CWA...A SECOND ALONG THE HIGHWAY 1 CORRIDOR AND A
THIRD THROUGH THE TRIAD JUST EAST OF THE I-85 CORRIDOR. THESE TWO
LINES WILL GRADUALLY PUSH EASTWARD THIS AFTERNOON BRINGING MORE
HEAVY RAIN TO AN AREA ALREADY RECEIVING 2-3 INCHES OF RAIN IN SOME
LOCATIONS. THAT BEING SAID...RAIN RATES HAVE BEEN LOW ENOUGH AND
ENOUGH TIME HAS PASSED SINCE THE LAST RAINFALL THAT FLOODING SHOULD
NOT BE A WIDESPREAD PROBLEM THIS AFTERNOON. MORE LOCALIZED FLOODING
IS POSSIBLE WITH HEAVIER SHOWERS ESPECIALLY IN URBAN AREAS AND IN
THE NORMALLY FLASHY SMALLER CREEKS. RAINFALL TOTALS THIS AFTERNOON
WILL RANGE FROM A TENTH TO A QUARTER OF AN INCH OR SO WITH LOCALLY
HEAVIER AMOUNTS IN STRONGER STORMS. TRAINING OF STORMS SHOULD NOT BE
AS BIG OF A PROBLEM THIS AFTERNOON AND EVENING AS IT WAS EARLIER
THIS MORNING.
DESPITE THE SHORTWAVE ENERGY SEVERE POTENTIAL THIS AFTERNOON STILL
LOOKS EXTREMELY LIMITED. BOTH LOW AND MID-LEVEL LAPSE RATES ARE VERY
WEAK...AS IS THE EFFECTIVE SHEAR WHICH IS LESS THAN 15 KNOTS IN ALL
LOCATIONS. ML CAPE VALUES REMAIN BETWEEN 500-1000...LIMITED BY THE
CONTINUED BROKEN TO OVERCAST SKIES THIS AFTERNOON. THAT BEING SAID A
FEW CELL MERGERS HAVE ALLOWED SOME SHOWERS TO GROW TO A LEVEL
SUPPORTIVE OF VERY SMALL HAIL AND LIGHTNING. OTHERWISE HEAVY RAIN
AND MINOR FLOODING WILL CONTINUE TO BE THE MAIN THREAT OF THE DAY.
EXPECT WINDS THIS AFTERNOON TO GENERALLY BE SOUTHWESTERLY AT 5-10
KNOTS WITH THE OCCASIONAL GUST TO 15-20 KNOTS IN SHOWERS. HIGH
TEMPERATURES TODAY WILL MOST LIKELY VARY DEPENDING ON LOCATION WITH
A FEW BREAKS IN THE CLOUDS SUPPORTIVE OF HIGHS NEAR 80 WITH THOSE
LOCATIONS MAINTAINING OVERCAST SKIES TO TOP OUT IN THE MID TO UPPER
70S.
TONIGHT: HIGH RESOLUTION CONVECTIVE ALLOWING MODELS SUPPORT SHOWER
AND THUNDERSTORM ACTIVITY ENDING IN THE WEST AFTER 00Z AND
CONTINUING THROUGH 3Z IN THE EAST. THE ACCURACY OF THESE
MODELS...ESPECIALLY THE HRRR WAS BETTER EARLIER IN THE DAY THAN IT
IS NOW BUT THE SOLUTION STILL SEEMS REASONABLE GIVEN THE LOCATION OF
THE SHORTWAVE TO THE NORTH. AFTER CONVECTION ENDS EXPECT ISSUES WITH
FOG/LOW CEILINGS AND SUB-VFR VISIBILITIES AT ALL SITES OVERNIGHT.
THIS WILL CONTINUE THROUGH SUNRISE TUESDAY. LOWS WILL BE IN THE
LOWER TO MID 60S NW TO SE.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...
TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.
MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.
TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 240 PM MONDAY...
FOR WEDNESDAY...WEAK SHORTWAVE RIDGING WILL BUILD OVER THE AREA...
WHILE AT THE SURFACE...THE BERMUDA HIGH WILL RIDGE WESTWARD INTO THE
CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN EVEN FURTHER DECREASE IN
PRECIP COVERAGE. HOWEVER...SUFFICIENT MOISTURE WILL STILL BE IN
PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR 1.5 INCHES OR
SO. THEREFORE...AM STILL EXPECTING TO SEE WIDELY SCATTERED TO
SCATTERED DIURNALLY DRIVEN CONVECTION...WITH THE HIGHEST CHANCES
BEING ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HIGHS ONCE
AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS IN THE
MID/UPPER 60S.
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WORK WEEK AS THE MID/UPPER LEVEL RIDGE SHIFTS
OFFSHORE AHEAD OF OUR NEXT MID/UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT. MODELS REMAIN IN GENERAL AGREEMENT WITH BRINGING THE
FRONT THROUGH THE FORECAST AREA LATE THURSDAY NIGHT/EARLY FRIDAY.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. BULK SHEAR VALUES WILL INCREASE TO
AROUND 25 KNOTS OR SO...THEREFORE BETTER STORM ORGANIZATION IS
EXPECTED...HOWEVER THE BEST UPPER LEVEL FORCING WILL PASS WELL TO
OUR NORTH. THEREFORE...EVEN THOUGH AN ISOLATED SEVERE STORM CANNOT
BE COMPLETELY RULED OUT...THE OVERALL THREAT REMAINS LOW AT THIS
TIME. WITH THE INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND
FRIDAY...TEMPS WILL MOSTLY BE IN THE LOW/MID 80S.
IT STILL APPEARS THE WEEKEND AND INTO EARLY NEXT WEEK WILL BE DRY AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT. SLIGHTLY COOLER
TEMPS ARE EXPECTED DURING THIS TIME FRAME...GENERALLY THE UPPER 70S
TO LOWER 80S...WITH OVERNIGHT LOWS IN THE 50S.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 750 PM MONDAY...
24 HOUR TAF PERIOD:
CONVECTIVE COVERAGE CONTINUES TO DIMINISH WITH LOSS OF DAYTIME
HEATING. HOWEVER AN ISOLATED TO WIDELY SCATTERED SHOWERS WILL BE
POSSIBLE THROUGH THE OVERNIGHT HOURS. MUCH LIKE LAST NIGHT...EXPECT
WIDESPREAD LIFR TO IFR CONDITIONS TO DEVELOP BETWEEN 06 TO 12Z
TUESDAY...WITH THE POTENTIAL FOR SOME FOG TO DEVELOP IN THE WEST.
CEILINGS SHOULD IMPROVE TO VFR BY 15Z TUESDAY WITH ISOLATED TO
SCATTERED SHOWERS AND STORMS DURING THE AFTERNOON AND EVENING.
LONG TERM:
LOW STRATUS AND FOG ARE EXPECTED EACH MORNING UNTIL A COLD FRONTAL
PASSAGE ON FRIDAY. DIURNAL STORMS ARE EXPECTED ON WEDNESDAY
AFTERNOON WITH THE COLD FRONTAL BRINGING A CHANCE FOR SHOWERS AND
THUNDERSTORMS THURSDAY AND THURSDAY NIGHT. CONDITIONS RETURN TO THE
AREA ON FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ELLIS
NEAR TERM...ELLIS
SHORT TERM...ELLIS
LONG TERM...KRR
AVIATION...CBL
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
932 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A WARM FRONT WILL MOVE NORTH OF EASTERN NORTH CAROLINA TODAY. HIGH
PRESSURE WILL BUILD OVER THE AREA MONDAY AND PERSIST THROUGH LATE
WEEK. A FRONT WILL APPROACH THE AREA LATE IN THE WEEK AND MOVE
THROUGH EASTERN NORTH CAROLINA FRIDAY NIGHT INTO EARLY SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 925 AM SUNDAY...THE 12Z MHX SOUNDING REVEALS A VERY MOIST
ATMOSPHERE ACROSS ERN NC. THE LATEST RAP MODEL IS A BIT OVERDONE
ON THE COVERAGE OF SHOWERS...WHICH CURRENTLY IS LIMITED TO MAINLY
THE NORTHERN OUTER BANKS...SO HAVE LOWERED POPS A BIT FOR THIS
MORNING. WITH ADDITIONAL ACTIVITY UPSTREAM...AND GIVEN THE MOIST
UNSTABLE ENVIRONMENT...EXPECT ADDITIONAL SHOWERS/TSTMS TO
REDEVELOP DURING THE AFTERNOON. FORECAST STORM MOTION IS ONLY
ABOUT 8 KNOTS WHICH WOULD LEAD TO POSSIBLE HEAVY RAINFALL AMOUNTS
IN SPOTS. ALSO GIVEN THE LARGE PROJECTED CAPE VALUES...WOULD
ANTICIPATE A GOOD OF LIGHTNING WITH THE HEAVIER CELLS. WITH SOME
FILTERED SUNSHINE THIS MORNING...AND WITH TEMPERATURE READINGS
ALREADY NEARING FORECAST HIGHS...HAVE BUMPED TEMPERATURES UP A FEW
DEGREES ALONG THE COAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
AS OF 330 AM SUNDAY...CONVECTION WILL CONTINUE TONIGHT ENHANCED BY
THE UPR LEVEL TROUGH...AND INCREASING OVERALL AMS MOISTURE WITH
PWAT VALUES INCREASE TO AROUND 1.75 INCHES. ANOTHER MILD NIGHT
WITH LOWS IN THE MID AND UPR 60S UNDER MOCLDY SKIES.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 3 AM SUN...MONDAY STILL HAS THE POTENTIAL TO BE RATHER WET
AS A MID-LEVEL TROUGH LINGERS IN THE AREA...COMBINED WITH AN
INFLUX OF LOW-LEVEL MOISTURE FROM THE SOUTH AND SOUTHWEST AS
PWAT VALUES APPROACH 1.75 INCHES. WILL CONTINUE LIKELY POPS.
ISOLATED STRONG TSTMS WILL BE POSSIBLE MON AND MON NIGHT...THOUGH
AT THIS TIME THINK BIGGEST THREAT IS HEAVY RAIN WITH MINOR
FLOODING POSSIBLE. THE MID-LEVEL TROUGH SHOULD MOVE OFFSHORE
MONDAY NIGHT INTO EARLY TUE WITH UPPER HEIGHTS SLOWLY BUILDING
TUESDAY. EXPECT SEABREEZE TO TRIGGER SOME SHOWERS/TSTMS TUE
AFTERNOON AND INCREASED POPS TO CHANCE. WITH A MID-LEVEL RIDGE IN
PLACE...EXPECT WEDNESDAY TO BE GENERALLY DRY AND WARM...THOUGH
MODELS NOW TRYING TO DEVELOP SOME LIGHT PRECIP INLAND. MOISTURE
WILL INCREASE AGAIN ON THURSDAY WITH AN INCREASING LOW-LEVEL
SOUTHWEST FLOW AHEAD OF A DEEPENING UPPER TROUGH AND APPROACHING
STRONG COLD FRONT. POPS WILL GRADUALLY INCREASE THURSDAY INTO
FRIDAY AS THE UPPER TROUGH DEEPENS. BY SATURDAY...THE COLD FRONT
FINALLY PUSHES THROUGH THE REGION WITH ANY LEFTOVER PRECIPITATION
TAKING ON A MORE STRATIFORM NATURE WITH MUCH COOLER AIR DIGGING
SOUTHWARD.
TEMPS THROUGH THE WEEK NEAR OR SLIGHTLY ABOVE NORMAL WITH HIGHS
IN THE MID 70S/MID 80S AND OVERNIGHT LOWS IN THE 60S. COOLER AIR
EXPECTED BEHIND THE FRONT SAT WITH N/NE FLOW DEVELOPING.
&&
.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
SHORT TERM /THROUGH TONIGHT/...
AS OF 600 AM SUNDAY...MVFR TO OCNLY IFR CIGS AND VSBYS ESPECIALLY
AT THOSE THAT THOSE TAF SITES...LIKE EWN...THAT RECEIVED RAFL
YESTERDAY THROUGH 12Z. OTRW VFR CONDITIONS EXPECTED OUTSIDE OF SCT
CONVECTION MAINLY DURG THE AFTERNOON CONTG INTO THE EVE HOURS.
LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM SUN...PREDOMINATE VFR CONDITIONS EXPECTED THROUGH THE
PERIOD...THOUGH WILL LIKELY SEE PERIODS OF SUB-VFR CONDITIONS AS
SCATTERED SHOWERS AND TSTMS ARE EXPECTED MONDAY INTO TUE...WITH
BEST CHANCES MON. CONVECTION WILL BECOME MORE DIURNALLY DRIVEN
MID TO LATE WEEK. PATCHY FOG/STRATUS WILL BE POSSIBLE EACH NIGHT
GIVEN DEEP MOISTURE AND LIGHT WINDS.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 935 AM SUNDAY...NO MAJOR CHANGES MADE TO FORECAST AS A
GENERAL LIGHT TO MODERATE S/SSE FLOW CONTINUES ON THE COASTAL
WATERS AND SOUNDS. SEAS ARE IN THE 3 TO 5 FOOT RANGE. EXPECT THIS
TREND TO CONTINUE...OUTSIDE OF CONVECTION...THROUGH THE AFTERNOON
AND INTO TONIGHT.
LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM SUN...HIGH PRESSURE WILL CONTINUE TO EXTEND OVER THE
WATERS FROM OFFSHORE THROUGH THE PERIOD...WITH A LIGHT TO MODERATE
S/SSW FLOW 10-20KT PERSISTING AND SEAS REMAINING 2-5FT. MARGINAL
SCA CONDITIONS COULD BE POSSIBLE OVER THE CENTRAL WATERS MONDAY
AND MONDAY NIGHT...THOUGH WILL CONTINUE TO CAP SEAS AT 5FT DUE TO
CONFIDENCE.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JAC
NEAR TERM...CTC
SHORT TERM...JAC
LONG TERM...CTC/CQD
AVIATION...JAC/CQD
MARINE...JAC/CTC/CQD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1008 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1008 PM CDT MON MAY 20 2013
MAIN UPDATE THIS EVENING WAS TO ADJUST THE WIND ADVISORY. WINDS
ARE DIMINISHING QUICKLY IN THE NORTHWEST AND EXPECT WINDS
SOUTHWEST TO DROP SOON. THEREFORE WILL CANCEL THE ADVISORY IN THE
WEST. WILL KEEP IT GOING IN THE CENTRAL THROUGH 1 AM CDT. DID
EXTEND THE ADVISORY OVER EASTERN PORTIONS OF CENTRAL NORTH DAKOTA
THROUGH 7 AM BASED MAINLY ON RAP ANALYSIS KEEPING 40-45 KNOT WINDS
AT 925MB INTO THE EARLY MORNING HOURS.
UPDATE ISSUED AT 734 PM CDT MON MAY 20 2013
QUICK UPDATE JUST TO FRESHEN UP GRIDS NOT UPDATED WITH THE
EXPANSION OF THE WIND ADVISORY. NO CHANGES TO THE ADVISORY AT THIS
TIME. WITH NEXT UPDATE MAY NEED TO LOOK INTO EXTENDING EASTERN
COUNTIES THROUGH THE NIGHT. MADE SOME MINOR ADJUSTMENTS TO POPS
THROUGH THE EVENING.
UPDATE ISSUED AT 540 PM CDT MON MAY 20 2013
UPDATE LATE THIS AFTERNOON DUE TO STRONG WINDS. WILL EXTEND THE
WIND ADVISORY FARTHER SOUTH TO INCLUDE AREAS ALONG AND NORTH OF
INTERSTATE 94.
VERY STRONG WINDS ACROSS FAR NORTH CENTRAL NORTH DAKOTA LATE THIS
AFTERNOON WITH WIND GUST TO 48KTS RECORDED AT ROLLA. CURRENT GUSTS
HAVE SUBSIDED BACK TO AROUND 40-42 KNOTS. WILL CONTINUE TO MONITOR
FOR POSSIBLE HIGH WIND WARNING THIS EVENING.
LATEST RAP ANALYSIS SHOWS AROUND 40-45 KNOTS OF WIND AT 925 MB
THROUGH MID EVENING...MAINLY ALONG AND EAST OF THE HIGHWAY 83
CORRIDOR AND ALONG AND NORTH OF INTERSTATE 94. ALSO 850 KNOT WINDS
INCREASE EARLY THIS EVENING ACROSS MUCH OF CENTRAL NORTH DAKOTA.
AFTER COORDINATION WITH FGF...WILL EXTEND THE CURRENT WIND
ADVISORY FARTHER SOUTH TO ALONG AND NORTH OF INTERSTATE 94...AND
KEEP AN EYE ON WINDS ACROSS THE FAR NORTH CENTRAL...HOLDING OFF ON
A HIGH WIND WARNING AT THIS TIME.
OTHERWISE NO SIGNIFICANT CHANGES TO THE FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE HIGHLIGHT OF THE SHORT TERM CONTINUES TO BE THE IMPACTS OF THE
ONGOING RAINFALL EVENT.
OVERALL THE GUIDANCE IS IN GOOD AGREEMENT...AND FOLLOWED A BLEND
OF THE 12 UTC GFS/GEM/ECMWF AND 15 UTC SREF FOR ALL FIELDS.
CURRENTLY THE STACKED LOW ACROSS FAR NORTHEAST SOUTH DAKOTA IS
EXPECTED TO SLOWLY PROPAGATE INTO CENTRAL MINNESOTA THROUGH
TUESDAY. WRAP AROUND RAINFALL IS EXPECTED TO SLOWLY DOWNTREND
THROUGH THE NIGHT AND INTO TUESDAY WITH AN ADDITIONAL ONE HALF TO
THREE QUARTERS OF AN INCH OF RAINFALL EXPECTED. SEE THE HYDROLOGY
DISCUSSION BELOW FOR DETAILS.
FOR THIS EVENING AND TONIGHT...DID MAINTAIN THE WIND ADVISORY FOR
THE WEST AND NORTH. THE WIND FIELD ACROSS THESE AREAS CONTINUES TO
STRENGTHEN WITH 40-45 KTS AT THE TOP OF A SHALLOW MIXED LAYER AS
DEPICTED BY THE 12 UTC NAM/GFS BUFR SOUNDINGS. THE STRONGEST WINDS
ARE EXPECTED ACROSS THE TURTLE MOUNTAINS WHERE GUSTS TO NEAR 50
MPH ARE POSSIBLE THROUGH EARLY EVENING.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE MAIN FORECAST ISSUE THROUGH THE LONG TERM PERIOD WILL BE ONGOING
RIVER AND OVERLAND FLOODING CONCERNS. SEE HYDROLOGY DISCUSSION BELOW
FOR DETAILS. THEN ATTENTION TURNS TO THE UPCOMING WEEKEND AND THE
POSSIBILITY FOR SCATTERED THUNDERSTORMS AND POSSIBLE SEVERE WEATHER.
THERE IS FAIRLY GOOD MODEL AGREEMENT REGARDING THE POSITION AND
MOVEMENT OF THE CLOSED UPPER LEVEL LOW...ASSOCIATED WITH THE
PERSISTENT RAINS FOR THE PAST SEVERAL DAYS. THE UPPER LOW IS
FORECAST TO BE OVER THE SD/MN BORDER TUESDAY EVENING...THEN BECOME
MORE OF AN OPEN WAVE BY WEDNESDAY EVENING OVER IA/WI/IL AND THE
WESTERN GREAT LAKES. THIS SCENARIO WILL MEAN THE VERY HIGH/LIKELY
CHANCES OF RAIN TUESDAY NIGHT IN THE JAMES RIVER BASIN WILL LESSEN
TO SCATTERED IN NATURE BY WEDNESDAY. THE REST OF WESTERN AND CENTRAL
NORTH DAKOTA SHOULD SEE A DECREASE IN COVERAGE OF THE SHOWERS
TUESDAY NIGHT. SLIGHT CHANCES TO SCATTERED SHOWERS WEDNESDAY AS THE
SYSTEM MOVES EAST OF THE REGION.
BY WEDNESDAY EVENING AS THE UPPER LEVEL LOW/TROUGH MOVES EAST...A
WEAK UPPER LEVEL RIDGE WILL BUILD ACROSS THE NORTHERN PLAINS. THIS
WILL BE SHORT-LIVED AS ANOTHER LARGE UPPER LEVEL LOW/TROUGH SYSTEM
MOVES INTO THE PACIFIC NORTHWEST AND ROCKIES. THUS NO PRECIPITATION
MENTION FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
FRIDAY THROUGH THE WEEKEND AND INTO MONDAY...THE UPPER LEVEL LOW
OVER THE ROCKIES IS FORECAST TO REMAIN IN PLACE...SETTING UP A
PROLONGED PERIOD OF SOUTHWESTERLY FLOW ALOFT FOR NORTH DAKOTA. THIS
WILL MEAN PERIODIC UPPER LEVEL SHORTWAVE ENERGY MOVING NORTHEASTWARD
THROUGH THE MEAN FLOW. AT THE SURFACE...THIS WILL RESULT IN BROAD
LOW PRESSURE ACROSS THE PLAINS...ALLOWING PLENTY OF GULF OF MEXICO
MOISTURE TO STREAM NORTHWARD. A PROLONGED LOW LEVEL JET AT H925-H850
WILL HELP TRANSPORT MOISTURE AND ENERGY NORTHWARD UP THE PLAINS.
THUS PERIODIC EPISODES OF SCATTERED THUNDERSTORMS WILL BE IN THE
FORECAST FRIDAY THROUGH THE MEMORIAL DAY WEEKEND.
WHILE TOO FAR OUT FOR MUCH CERTAINTY IN NARROWING DOWN SPECIFIC
AREAS OF CONCERN...SURFACE DEWPOINTS RISING INTO THE 50S BY FRIDAY
AND FORECAST CAPE DEVELOPING FROM THE SOUTHERN...CENTRAL...TO THE
NORTHERN PLAINS WOULD SUGGEST SOME SEVERE THUNDERSTORM ACTIVITY OVER
A BROAD AREA OF THE PLAINS FRIDAY AND SATURDAY. STAY TUNED FOR LATER
FORECASTS AND STORM PREDICTION CENTER OUTLOOKS FOR THE POTENTIAL FOR
SEVERE THUNDERSTORMS THIS COMING WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 1008 PM CDT MON MAY 20 2013
LIGHT TO MODERATE RAINFALL WILL CONTINUE OVER ALL TERMINALS
THROUGH THE TAF PERIOD WITH MVFR/IFR CIGS/VSBYS. WIND GUSTS OF
30-40 KTS ARE POSSIBLE AT ALL TAF SITES LATE THIS AFTERNOON AND
THIS EVENING.
&&
.HYDROLOGY...
ISSUED AT 330 PM CDT MON MAY 20 2013
DID MAINTAIN THE FLOOD WATCH FOR ALL OF WESTERN AND CENTRAL NORTH
DAKOTA THROUGH TONIGHT. CALLS TO AREA EMERGENCY MANAGERS REVEAL THAT
FOR THE MOST PART...COUNTY AND TOWNSHIP ROAD IMPACTS ARE LIMITED.
HOWEVER...AS SOILS CONTINUE TO SATURATE...OVERLAND FLOOD CONCERNS
COULD INCREASE THROUGH THE NIGHT. FURTHERMORE...REPORTS HAVE BEEN
COMING IN OF WATER ENTERING BASEMENTS ACROSS THE AREA WITH THE
SATURATED GROUND. ADDITIONAL RIVER AND STREAM RISES ARE EXPECTED
OVER THE COMING DAYS. FOR THE MOST PART WITHIN BANK RISES ARE
ANTICIPATED. HOWEVER...THE SOURIS RIVER AT TOWNER IS EXPECTED TO
RISE ABOVE FLOOD STAGE AGAIN...THE PIPESTEM CREEK NEAR PINGREE IS
FORECAST TO RISE ABOVE MINOR FLOOD STAGE TOMORROW AFTERNOON WITH
THE WILLOW CREEK NEAR WILLOW CITY POSSIBLY APPROACHING FLOOD STAGE
BY WEDNESDAY EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 7 AM CDT /6 AM MDT/ TUESDAY FOR NDZ001>005-
009>013-017>023-025-031>037-040>048-050-051.
WIND ADVISORY UNTIL 1 AM CDT /MIDNIGHT MDT/ TUESDAY FOR
NDZ001>005-009>013-017>023-025-031>037-040-041-043-044.
&&
$$
UPDATE...TWH
SHORT TERM...AYD
LONG TERM...JV
AVIATION...TWH
HYDROLOGY...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
955 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 955 PM CDT MON MAY 20 2013
THE FORECAST IS IN GOOD SHAPE AND NO CHANGES ARE NEEDED AT THIS
POINT. THE COVERAGE OF THE SHOWERS IS DECREASING ACROSS THE
EASTERN FA...BUT THIS WAS HANDLED IN THE PREVIOUS UPDATE...AND
THINK THAT THIS AREA WILL AGAIN FILL IN BY LATER TONIGHT. THE
STEADIER RAINS MAY COME TO AN END...BUT MOST AREAS WILL STILL
RECEIVE MEASURABLE RAINFALL WITHIN EACH 6 HOUR PERIOD. WINDS ARE
ALSO ON TRACK WITH PREVIOUS THINKING.
MADE SOME CALLS AROUND THE REGION IN AN ATTEMPT TO SEE IF THERE
ARE ANY AREAL FLOODING PROBLEMS (OTHER THAN WHERE THE CURRENT
AREAL FLOOD WARNING IS ISSUED). REPORTS INDICATE THAT EVEN WHERE
2-5 INCHES OF RAIN OCCURRED...NO PROBLEMS OTHER THAN MINOR PONDING
EXIST. ONE THOUGHT IS THAT MOST AREAS HAVE BEEN WITHOUT SNOWCOVER
FOR SOME TIME...AND MUCH OF THE RAIN HAS BEEN ABLE TO SOAK INTO
THE GROUND. HOWEVER...WITHIN THE CURRENT AREAL FLOOD
WARNING...SNOWCOVER LASTED LONGER...AND THE SOIL IS MORE SATURATED
WHICH IS CAUSING MUCH MORE RUNOFF (PLUS THIS AREA GOT A LOT MORE
RAIN). THE FLOOD WATCH WILL REMAIN IN AFFECT FOR THE ENTIRE AREA
AS WATER MAY STILL BE RUNNING OFF AND COULD POTENTIALLY CAUSE
PROBLEMS WITHIN THE NEXT COUPLE DAYS.
UPDATE ISSUED AT 709 PM CDT MON MAY 20 2013
CONTINUING TO WATCH WINDS ACROSS THE NW FA...AND SO FAR THEY ARE
REMAINING WITHIN ADVISORY CRITERIA. THIS SHOULD REMAIN THE CASE
CONSIDERING THERE IS NO STRONG MECHANISM TO MIX THE WINDS TO THE
SURFACE. LAV GUIDANCE IS DOING WELL WITH CURRENT WIND SPEEDS...AND
INDICATES 30-40MPH WINDS CONTINUING ACROSS THE DEVILS LAKE BASIN
THROUGH SUNRISE ON TUESDAY. THE RAP INDICATES WINDS ALOFT (925MB)
REMAIN AOA 35 KNOTS UNTIL 15Z TUE. WILL EXTENT THE WIND ADVISORY
ACROSS THE WESTERN FA UNTIL 15Z TUE.
STEADY RAIN CONTINUES ALONG AND WEST OF THE VALLEY...WITH AN AREA
OF MORE SCATTERED SHOWERS EAST OF THE VALLEY. WAVES WILL CONTINUE
TO ROTATE AROUND THE MAIN UPPER LOW...AND WILL NOT ADJUST POPS TOO
MUCH. HOWEVER...WILL INDICATE THE MORE SCATTERED NATURE OF THE
SHOWERS FOR THE NEXT 6 HOURS ACROSS THE SE FA.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 339 AM CDT MON MAY 20 2013
VERY SEVERE FLOODING SITUATION OVER PARTS OF NORTHEASTERN NORTH
DAKOTA. KMVX 88D STORM PRECIP TOTALS EITHER VIA LEGACY STP OR THE
NEW DUAL POL ARE WOEFULLY UNDERDONE ESPECIALLY IN NORTHEASTERN
NORTH DAKOTA. SENT OUT A LONG LIST OF RAINFALL REPORTS SO FAR
WIDESPREAD 1-3 INCHES WITH POCKET OF 4-6 INCHES OR MORE FROM HOMME
DAM NEAR PARK RIVER ND UP THROUGH CRYSTAL TO MOUNTAIN ND TO
WALHALLA. LOTS OF CREEK FLOODING AND OVERLAND FLOODING THERE AND
UPDATED AREAL FLOOD WARNING FOR THIS AREA.
FOR TONIGHT EXPECT CONTINUED RAIN...THOUGH A BIT DRIER AIR ALOFT
SHOULD MEAN RAIN WILL BECOME MORE SCATTERED AND LIGHTER AS THE
NIGHT GOES ALONG. SOME THUNDER IN DRY SLOT FROM LITTLE FALLS TO ST
CLOUD AND SOME ISOLD THUNDER MAY MAKE IT INTO SOUTHEASTERN ZONES
THIS EVE. OTHERWISE JUST RAIN. ANOTHER HALF INCH OR A BIT MORE
THRU TONIGHT ISOLD 1 INCH MORE IN THE SOUTH TONIGHT. THE SOUTHERN
AREAS HAVE HAD THE LEAST AND CAN TAKE IT. WILL MAINTAIN AREAL
FLOOD WATCH AS ISSUED EARLIER.
FOR WINDS EXPANDED WIND ADV TO ROSEAU COUNTY AS ROX AWOS CONTINUES
TO SEE WIND GUSTS OVER 40 KTS AND SUSTAINED WINDS 25-30 KTS.
EXPECT TO SEE WINDY CONDITIONS THRU 03Z BEFORE THEY DIMINISH.
WATER VAPOR SHOWS UPR LOW AND SFC LOW STACKED SOUTH OF SISSETON
AND THIS LOW WILL BE STATIONARY AND BEGIN TO DRIFT SOUTH AND EAST
LATE TONIGHT INTO TUESDAY. WILL SEE LIGHTER RAINFALL ON
TUESDAY....BUT FOCUS MORE ON THE SOUTH.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 339 AM CDT MON MAY 20 2013
SYSTEM WILL DROP SOUTH ON WEDNESDAY WITH CLEARING AND DRYING
MOVING SOUTH. MAINLY DRY WED NIGH INTO THURSDAY WITH HIGH PRESSURE
COMING IN. FOR THU NIGHT INTO EARLY FRI MOST OF THE FA SHOULD
REMAIN DRY WITH THE 500MB RIDGE AXIS STILL OVER THE AREA. HOWEVER
THIS IS FAIRLY SHORT LIVED AS THE FLOW QUICKLY BEGINS TO BECOME
MORE SOUTHWEST. THIS SWITCH TO SOUTHWEST FLOW WILL BRING ACTIVE
WEATHER BACK INTO THE FA FOR BASICALLY THE REMAINDER OF THE LONG
TERM PERIOD. OPERATIONAL MODEL RUNS TODAY ARE SHOWING THE
POSSIBILITY OF NORTHEAST FLOW ERODING SOME OF THIS PCPN
POTENTIAL...ESPECIALLY IN THE NORTHEAST FA. THEREFORE THE BEST
CHANCES FOR PCPN SHOULD PROBABLY BE OVER THE WESTERN FA WITH
LESSER CHANCES TO THE EAST.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 709 PM CDT MON MAY 20 2013
THE RAIN COVERAGE MAY DECREASE THROUGH THE NIGHT...BUT THERE WILL
CONTINUE TO BE PERIODS OF RAINFALL. CIGS WILL REMAIN LOW...LIKELY
FLUCTUATING BETWEEN IFR AND MVFR. WINDS STRONGEST AT KDVL...WITH
KGFK AND KTVF ALSO GUSTY. KBJI AND KFAR ARE CLOSEST TO THE SURFACE
LOW AND SHOULD HAVE THE LOWEST WIND SPEEDS...ALTHOUGH INCREASING
BY MORNING.
&&
.HYDROLOGY...
ISSUED AT 955 PM CDT MON MAY 20 2013
RAIN SHOWERS WILL CONTINUE TONIGHT AND TOMORROW ACROSS THE RED
RIVER BASIN AND ASSOCIATED TRIBUTARIES. OVER THE LAST 12 HOURS...
ONE INCH TO ONE AND ONE QUARTER INCH OF RAIN FELL OVER BUFFALO
RIVER BASIN AND THE RED RIVER BASIN IN THE VICINITY OF WAHPETON.
THIS HAS RESULTED IN NEW FORECASTS PUSHING THE CREST INTO MINOR
FLOOD STAGE. WITH SOME UNCERTAINTY ON HOW MUCH RAIN WILL FALL
OVER THE NEXT 24 HOURS...WILL ISSUE FLOOD WATCHES FOR THESE THREE
POINTS.
THREE TO FIVE INCHES TOTAL HAVE FALLEN ACROSS PARTS OF NORTHEASTERN
NORTH DAKOTA AND SITES ALONG THE FOREST AND PARK RIVERS ARE RISING
RAPIDLY. THERE IS ALSO PLENTY OF AREAL FLOODING TO RUN OFF INTO
THESE RIVERS...AND CONFIDENCE IS HIGH ENOUGH TO ISSUE WARNINGS FOR
MINOR FLOODING AT BOTH LOCATIONS. WILL ALSO NEED TO MONITOR THE
PEMBINA RIVER AT WALHALLA FOR THE POTENTIAL FOR MAJOR FLOODING.
A WARNING FOR MODERATE FLOODING IS CURRENTLY IN EFFECT...BUT MAY
NEED TO BE UPGRADED IF CURRENT TRENDS CONTINUE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...FLOOD WATCH THROUGH TUESDAY EVENING FOR NDZ006>008-014>016-024-
026>030-038-039-049-052>054.
WIND ADVISORY UNTIL 10 AM CDT TUESDAY FOR NDZ006-007-014-015-024-
026-028-038-054.
WIND ADVISORY UNTIL 1 AM CDT TUESDAY FOR NDZ008-016.
MN...FLOOD WATCH THROUGH TUESDAY EVENING FOR MNZ001>009-013>017-
022>024-027>032-040.
WIND ADVISORY UNTIL 1 AM CDT TUESDAY FOR MNZ004-005-007.
&&
$$
UPDATE...TG
SHORT TERM...RIDDLE
LONG TERM...RIDDLE/GODON
AVIATION...TG
HYDROLOGY...SPEICHER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
734 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 734 PM CDT MON MAY 20 2013
QUICK UPDATE JUST TO FRESHEN UP GRIDS NOT UPDATED WITH THE
EXPANSION OF THE WIND ADVISORY. NO CHANGES TO THE ADVISORY AT THIS
TIME. WITH NEXT UPDATE MAY NEED TO LOOK INTO EXTENDING EASTERN
COUNTIES THROUGH THE NIGHT. MADE SOME MINOR ADJUSTMENTS TO POPS
THROUGH THE EVENING.
UPDATE ISSUED AT 540 PM CDT MON MAY 20 2013
UPDATE LATE THIS AFTERNOON DUE TO STRONG WINDS. WILL EXTEND THE
WIND ADVISORY FARTHER SOUTH TO INCLUDE AREAS ALONG AND NORTH OF
INTERSTATE 94.
VERY STRONG WINDS ACROSS FAR NORTH CENTRAL NORTH DAKOTA LATE THIS
AFTERNOON WITH WIND GUST TO 48KTS RECORDED AT ROLLA. CURRENT GUSTS
HAVE SUBSIDED BACK TO AROUND 40-42 KNOTS. WILL CONTINUE TO MONITOR
FOR POSSIBLE HIGH WIND WARNING THIS EVENING.
LATEST RAP ANALYSIS SHOWS AROUND 40-45 KNOTS OF WIND AT 925 MB
THROUGH MID EVENING...MAINLY ALONG AND EAST OF THE HIGHWAY 83
CORRIDOR AND ALONG AND NORTH OF INTERSTATE 94. ALSO 850 KNOT WINDS
INCREASE EARLY THIS EVENING ACROSS MUCH OF CENTRAL NORTH DAKOTA.
AFTER COORDINATION WITH FGF...WILL EXTEND THE CURRENT WIND
ADVISORY FARTHER SOUTH TO ALONG AND NORTH OF INTERSTATE 94...AND
KEEP AN EYE ON WINDS ACROSS THE FAR NORTH CENTRAL...HOLDING OFF ON
A HIGH WIND WARNING AT THIS TIME.
OTHERWISE NO SIGNIFICANT CHANGES TO THE FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE HIGHLIGHT OF THE SHORT TERM CONTINUES TO BE THE IMPACTS OF THE
ONGOING RAINFALL EVENT.
OVERALL THE GUIDANCE IS IN GOOD AGREEMENT...AND FOLLOWED A BLEND
OF THE 12 UTC GFS/GEM/ECMWF AND 15 UTC SREF FOR ALL FIELDS.
CURRENTLY THE STACKED LOW ACROSS FAR NORTHEAST SOUTH DAKOTA IS
EXPECTED TO SLOWLY PROPAGATE INTO CENTRAL MINNESOTA THROUGH
TUESDAY. WRAP AROUND RAINFALL IS EXPECTED TO SLOWLY DOWNTREND
THROUGH THE NIGHT AND INTO TUESDAY WITH AN ADDITIONAL ONE HALF TO
THREE QUARTERS OF AN INCH OF RAINFALL EXPECTED. SEE THE HYDROLOGY
DISCUSSION BELOW FOR DETAILS.
FOR THIS EVENING AND TONIGHT...DID MAINTAIN THE WIND ADVISORY FOR
THE WEST AND NORTH. THE WIND FIELD ACROSS THESE AREAS CONTINUES TO
STRENGTHEN WITH 40-45 KTS AT THE TOP OF A SHALLOW MIXED LAYER AS
DEPICTED BY THE 12 UTC NAM/GFS BUFR SOUNDINGS. THE STRONGEST WINDS
ARE EXPECTED ACROSS THE TURTLE MOUNTAINS WHERE GUSTS TO NEAR 50
MPH ARE POSSIBLE THROUGH EARLY EVENING.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE MAIN FORECAST ISSUE THROUGH THE LONG TERM PERIOD WILL BE ONGOING
RIVER AND OVERLAND FLOODING CONCERNS. SEE HYDROLOGY DISCUSSION BELOW
FOR DETAILS. THEN ATTENTION TURNS TO THE UPCOMING WEEKEND AND THE
POSSIBILITY FOR SCATTERED THUNDERSTORMS AND POSSIBLE SEVERE WEATHER.
THERE IS FAIRLY GOOD MODEL AGREEMENT REGARDING THE POSITION AND
MOVEMENT OF THE CLOSED UPPER LEVEL LOW...ASSOCIATED WITH THE
PERSISTENT RAINS FOR THE PAST SEVERAL DAYS. THE UPPER LOW IS
FORECAST TO BE OVER THE SD/MN BORDER TUESDAY EVENING...THEN BECOME
MORE OF AN OPEN WAVE BY WEDNESDAY EVENING OVER IA/WI/IL AND THE
WESTERN GREAT LAKES. THIS SCENARIO WILL MEAN THE VERY HIGH/LIKELY
CHANCES OF RAIN TUESDAY NIGHT IN THE JAMES RIVER BASIN WILL LESSEN
TO SCATTERED IN NATURE BY WEDNESDAY. THE REST OF WESTERN AND CENTRAL
NORTH DAKOTA SHOULD SEE A DECREASE IN COVERAGE OF THE SHOWERS
TUESDAY NIGHT. SLIGHT CHANCES TO SCATTERED SHOWERS WEDNESDAY AS THE
SYSTEM MOVES EAST OF THE REGION.
BY WEDNESDAY EVENING AS THE UPPER LEVEL LOW/TROUGH MOVES EAST...A
WEAK UPPER LEVEL RIDGE WILL BUILD ACROSS THE NORTHERN PLAINS. THIS
WILL BE SHORT-LIVED AS ANOTHER LARGE UPPER LEVEL LOW/TROUGH SYSTEM
MOVES INTO THE PACIFIC NORTHWEST AND ROCKIES. THUS NO PRECIPITATION
MENTION FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
FRIDAY THROUGH THE WEEKEND AND INTO MONDAY...THE UPPER LEVEL LOW
OVER THE ROCKIES IS FORECAST TO REMAIN IN PLACE...SETTING UP A
PROLONGED PERIOD OF SOUTHWESTERLY FLOW ALOFT FOR NORTH DAKOTA. THIS
WILL MEAN PERIODIC UPPER LEVEL SHORTWAVE ENERGY MOVING NORTHEASTWARD
THROUGH THE MEAN FLOW. AT THE SURFACE...THIS WILL RESULT IN BROAD
LOW PRESSURE ACROSS THE PLAINS...ALLOWING PLENTY OF GULF OF MEXICO
MOISTURE TO STREAM NORTHWARD. A PROLONGED LOW LEVEL JET AT H925-H850
WILL HELP TRANSPORT MOISTURE AND ENERGY NORTHWARD UP THE PLAINS.
THUS PERIODIC EPISODES OF SCATTERED THUNDERSTORMS WILL BE IN THE
FORECAST FRIDAY THROUGH THE MEMORIAL DAY WEEKEND.
WHILE TOO FAR OUT FOR MUCH CERTAINTY IN NARROWING DOWN SPECIFIC
AREAS OF CONCERN...SURFACE DEWPOINTS RISING INTO THE 50S BY FRIDAY
AND FORECAST CAPE DEVELOPING FROM THE SOUTHERN...CENTRAL...TO THE
NORTHERN PLAINS WOULD SUGGEST SOME SEVERE THUNDERSTORM ACTIVITY OVER
A BROAD AREA OF THE PLAINS FRIDAY AND SATURDAY. STAY TUNED FOR LATER
FORECASTS AND STORM PREDICTION CENTER OUTLOOKS FOR THE POTENTIAL FOR
SEVERE THUNDERSTORMS THIS COMING WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 734 PM CDT MON MAY 20 2013
LIGHT TO MODERATE RAINFALL WILL CONTINUE OVER ALL TERMINALS
THROUGH THE TAF PERIOD WITH MVFR/IFR CIGS/VSBYS. WIND GUSTS OF
30-40 KTS ARE POSSIBLE AT ALL TAF SITES LATE THIS AFTERNOON AND
THIS EVENING.
&&
.HYDROLOGY...
ISSUED AT 330 PM CDT MON MAY 20 2013
DID MAINTAIN THE FLOOD WATCH FOR ALL OF WESTERN AND CENTRAL NORTH
DAKOTA THROUGH TONIGHT. CALLS TO AREA EMERGENCY MANAGERS REVEAL THAT
FOR THE MOST PART...COUNTY AND TOWNSHIP ROAD IMPACTS ARE LIMITED.
HOWEVER...AS SOILS CONTINUE TO SATURATE...OVERLAND FLOOD CONCERNS
COULD INCREASE THROUGH THE NIGHT. FURTHERMORE...REPORTS HAVE BEEN
COMING IN OF WATER ENTERING BASEMENTS ACROSS THE AREA WITH THE
SATURATED GROUND. ADDITIONAL RIVER AND STREAM RISES ARE EXPECTED
OVER THE COMING DAYS. FOR THE MOST PART WITHIN BANK RISES ARE
ANTICIPATED. HOWEVER...THE SOURIS RIVER AT TOWNER IS EXPECTED TO
RISE ABOVE FLOOD STAGE AGAIN...THE PIPESTEM CREEK NEAR PINGREE IS
FORECAST TO RISE ABOVE MINOR FLOOD STAGE TOMORROW AFTERNOON WITH
THE WILLOW CREEK NEAR WILLOW CITY POSSIBLY APPROACHING FLOOD STAGE
BY WEDNESDAY EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 7 AM CDT /6 AM MDT/ TUESDAY FOR NDZ001>005-
009>013-017>023-025-031>037-040>048-050-051.
WIND ADVISORY UNTIL 1 AM CDT /MIDNIGHT MDT/ TUESDAY FOR
NDZ001>005-009>013-017>023-025-031>037-040-041-043-044.
&&
$$
UPDATE...TWH
SHORT TERM...AYD
LONG TERM...JV
AVIATION...TWH
HYDROLOGY...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
709 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 709 PM CDT MON MAY 20 2013
CONTINUING TO WATCH WINDS ACROSS THE NW FA...AND SO FAR THEY ARE
REMAINING WITHIN ADVISORY CRITERIA. THIS SHOULD REMAIN THE CASE
CONSIDERING THERE IS NO STRONG MECHANISM TO MIX THE WINDS TO THE
SURFACE. LAV GUIDANCE IS DOING WELL WITH CURRENT WIND SPEEDS...AND
INDICATES 30-40MPH WINDS CONTINUING ACROSS THE DEVILS LAKE BASIN
THROUGH SUNRISE ON TUESDAY. THE RAP INDICATES WINDS ALOFT (925MB)
REMAIN AOA 35 KNOTS UNTIL 15Z TUE. WILL EXTENT THE WIND ADVISORY
ACROSS THE WESTERN FA UNTIL 15Z TUE.
STEADY RAIN CONTINUES ALONG AND WEST OF THE VALLEY...WITH AN AREA
OF MORE SCATTERED SHOWERS EAST OF THE VALLEY. WAVES WILL CONTINUE
TO ROTATE AROUND THE MAIN UPPER LOW...AND WILL NOT ADJUST POPS TOO
MUCH. HOWEVER...WILL INDICATE THE MORE SCATTERED NATURE OF THE
SHOWERS FOR THE NEXT 6 HOURS ACROSS THE SE FA.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 339 AM CDT MON MAY 20 2013
VERY SEVERE FLOODING SITUATION OVER PARTS OF NORTHEASTERN NORTH
DAKOTA. KMVX 88D STORM PRECIP TOTALS EITHER VIA LEGACY STP OR THE
NEW DUAL POL ARE WOEFULLY UNDERDONE ESPECIALLY IN NORTHEASTERN
NORTH DAKOTA. SENT OUT A LONG LIST OF RAINFALL REPORTS SO FAR
WIDESPREAD 1-3 INCHES WITH POCKET OF 4-6 INCHES OR MORE FROM HOMME
DAM NEAR PARK RIVER ND UP THROUGH CRYSTAL TO MOUNTAIN ND TO
WALHALLA. LOTS OF CREEK FLOODING AND OVERLAND FLOODING THERE AND
UPDATED AREAL FLOOD WARNING FOR THIS AREA.
FOR TONIGHT EXPECT CONTINUED RAIN...THOUGH A BIT DRIER AIR ALOFT
SHOULD MEAN RAIN WILL BECOME MORE SCATTERED AND LIGHTER AS THE
NIGHT GOES ALONG. SOME THUNDER IN DRY SLOT FROM LITTLE FALLS TO ST
CLOUD AND SOME ISOLD THUNDER MAY MAKE IT INTO SOUTHEASTERN ZONES
THIS EVE. OTHERWISE JUST RAIN. ANOTHER HALF INCH OR A BIT MORE
THRU TONIGHT ISOLD 1 INCH MORE IN THE SOUTH TONIGHT. THE SOUTHERN
AREAS HAVE HAD THE LEAST AND CAN TAKE IT. WILL MAINTAIN AREAL
FLOOD WATCH AS ISSUED EARLIER.
FOR WINDS EXPANDED WIND ADV TO ROSEAU COUNTY AS ROX AWOS CONTINUES
TO SEE WIND GUSTS OVER 40 KTS AND SUSTAINED WINDS 25-30 KTS.
EXPECT TO SEE WINDY CONDITIONS THRU 03Z BEFORE THEY DIMINISH.
WATER VAPOR SHOWS UPR LOW AND SFC LOW STACKED SOUTH OF SISSETON
AND THIS LOW WILL BE STATIONARY AND BEGIN TO DRIFT SOUTH AND EAST
LATE TONIGHT INTO TUESDAY. WILL SEE LIGHTER RAINFALL ON
TUESDAY....BUT FOCUS MORE ON THE SOUTH.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 339 AM CDT MON MAY 20 2013
SYSTEM WILL DROP SOUTH ON WEDNESDAY WITH CLEARING AND DRYING
MOVING SOUTH. MAINLY DRY WED NIGH INTO THURSDAY WITH HIGH PRESSURE
COMING IN. FOR THU NIGHT INTO EARLY FRI MOST OF THE FA SHOULD
REMAIN DRY WITH THE 500MB RIDGE AXIS STILL OVER THE AREA. HOWEVER
THIS IS FAIRLY SHORT LIVED AS THE FLOW QUICKLY BEGINS TO BECOME
MORE SOUTHWEST. THIS SWITCH TO SOUTHWEST FLOW WILL BRING ACTIVE
WEATHER BACK INTO THE FA FOR BASICALLY THE REMAINDER OF THE LONG
TERM PERIOD. OPERATIONAL MODEL RUNS TODAY ARE SHOWING THE
POSSIBILITY OF NORTHEAST FLOW ERODING SOME OF THIS PCPN
POTENTIAL...ESPECIALLY IN THE NORTHEAST FA. THEREFORE THE BEST
CHANCES FOR PCPN SHOULD PROBABLY BE OVER THE WESTERN FA WITH
LESSER CHANCES TO THE EAST.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 709 PM CDT MON MAY 20 2013
THE RAIN COVERAGE MAY DECREASE THROUGH THE NIGHT...BUT THERE WILL
CONTINUE TO BE PERIODS OF RAINFALL. CIGS WILL REMAIN LOW...LIKELY
FLUCTUATING BETWEEN IFR AND MVFR. WINDS STRONGEST AT KDVL...WITH
KGFK AND KTVF ALSO GUSTY. KBJI AND KFAR ARE CLOSEST TO THE SURFACE
LOW AND SHOULD HAVE THE LOWEST WIND SPEEDS...ALTHOUGH INCREASING
BY MORNING.
&&
.HYDROLOGY...
ISSUED AT 339 AM CDT MON MAY 20 2013
RIVER FLOOD WATCHES HAVE BEEN CANCELLED FOR THE RED RIVER AT
WAHPETON AND ITS SOUTHERN VALLEY MINNESOTA TRIBUTARIES.
RAINFALL AMOUNTS ARE EITHER INSUFFICIENT OR RUNOFF DUBIOUS TO
FORCE THESE POINTS TO FLOOD STAGE DURING THIS EVENT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...FLOOD WATCH THROUGH TUESDAY EVENING FOR NDZ006>008-014>016-024-
026>030-038-039-049-052>054.
WIND ADVISORY UNTIL 10 AM CDT TUESDAY FOR NDZ006-007-014-015-024-
026-028-038-054.
WIND ADVISORY UNTIL 1 AM CDT TUESDAY FOR NDZ008-016.
MN...FLOOD WATCH THROUGH TUESDAY EVENING FOR MNZ001>009-013>017-
022>024-027>032-040.
WIND ADVISORY UNTIL 1 AM CDT TUESDAY FOR MNZ004-005-007.
&&
$$
UPDATE...TG
SHORT TERM...RIDDLE
LONG TERM...RIDDLE/GODON
AVIATION...TG
HYDROLOGY...WJB
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1153 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 1153 PM CDT SAT MAY 18 2013
THOUGHTS REMAIN BASICALLY THE SAME AS BEFORE...BUT DID UPDATE POPS
BASED ON LATEST HRRR. HEAVY RAIN THREAT SEEMS TO BE THE MAIN
CONCERN...ESPECIALLY ACROSS SE ND. SPC HAS ISSUED A SEVERE
THUNDERSTORM WATCH FOR THIS AREA AS WELL...WITH INSTABILITY AROUND
MUCAPE 1000 J/KG AND FORCING TO INCREASE HERE.
UPDATE ISSUED AT 1006 PM CDT SAT MAY 18 2013
THUNDERSTORM COMPLEX APPROACHING FROM THE WEST IS SLOWING DOWN
(WAS MOVING AROUND 20 KNOTS AN HOUR AGO...NOW MOVING AROUND 10
KNOTS). THIS IS CAUSING VERY HEAVY RAINFALL...BUT ALSO MEANS THAT
THIS COMPLEX MAY NOT QUITE MAKE IT INTO THE FA. SOUTHERLY LOW
LEVEL FLOW IS INCREASING AS THE MEAN UPPER TROUGH SHIFTS
EAST...AND THIS IS LIKELY HALTING THE EASTWARD PROGRESS OF THIS
COMPLEX. 01Z HRRR STALLS THIS COMPLEX AND ACTUALLY DISSIPATES THE
ACTIVITY. THE MAIN FOCUS OVERNIGHT APPEARS THAT IT WILL COME FROM
THE SOUTH ALONG WITH INTENSE MOISTURE ADVECTION. SLIGHTLY ADJUSTED
POPS TO ACCOUNT FOR THE ABOVE THINKING. THE SEVERE THREAT STILL
APPEARS LIMITED FOR THIS FA. THE STORMS JUST WEST OF THE FA ARE
SEVERE...BUT THE SLOWING MOVEMENT WILL LIKELY WEAKEN THESE STORMS.
THE LOW LEVEL JET FOR LATER TONIGHT IS ONLY AROUND 25-30
KNOTS...AND ANY SEVERE THREAT GIVEN THE WEAKER INSTABILITY SHOULD
BE LIMITED.
THE MAIN CONCERN IS LIKELY FLASH FLOOD/HEAVY RAIN GIVEN THE SLOW
STORM MOVEMENT ALONG WITH PWATS APPROACHING 1.5 INCHES. WILL
MENTION LOCALIZED HEAVY RAIN IN THE GRIDS...BUT A FLASH FLOOD
WATCH IS NOT NEEDED IF THE ACTIVITY FROM THE WEST FALLS APART
BEFORE THE SOUTHERN ACTIVITY MOVES INTO THE REGION.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 300 PM CDT SAT MAY 18 2013
ALL EYES ON ANY CONVECTIVE DEVELOPMENT LATE THIS AFTN-EVE IN SE
ND-WCNTRL MN. SFC MAP SHOWS A BROAD SFC LOW IN THE MOBRIDGE SD
AREA WITH A BOUNDARY (COULD BE CALLED A WARM FRONT) FROM MOBRIDGE
TO OAKES THEN TO VALLEY CITY THEN TO HILLSBORO THEN EAST TO NORTH
OF DTL-PKD-BRD THEN INTO FAR NW WISCONSIN. IN FAR SE ND AND
ADJACENT PARTS OF WCNTRL CLOUDS CLEARED OUT ENOUGH TODAY FOR SFC
HEATING AND TEMPS IN THE 77 TO 81 DEGREE RANGE. SATELLITE SHOWS
WHAT APPEARS TO BE A CUMULUS CLOUD BOUNDARY FROM HILLSBORO TO
ALONG CLAY-NORMAN CO LINE TO NORTH OF PARK RAPIDS. SOUTH WINDS
SOUTH OF THIS FEATURE NR 10-13 KTS WHILE NORTH WINDS 5-8 KTS
NORTH OF THIS FEATURE. SPC SHOWS LITTLE CIN AND 1500 J/KG CAPE AND
SUFFICIENT BULK SHEAR. BUT UPPER LEVELS DONT SHOW ANY BIG THING TO
SET STUFF OFF. 17-18Z HRRR REFLECTIVITY DOES SHOW ONE CELL TRYING
TO GET GOING IN NORMAN CO. MN 22-23Z PD BUT THEN IT DISSIPATES
THIS EVE.
MUCH OF NORTHEAST SD HAS SEEN HIGH CLOUDS TODAY AND DEW PTS IN THE
50S AND SPC DOES HAVE SOME SFC BASED CIN IN THIS REGION. THUS MAY
BE HARD TO GET ANYTHING GOING THERE. BUT HRRR WANTS TO GENERATE
SOME ACTIVITY AXN-STC AREA BY 03Z.
ALSO SOME STORMS NR BLACK HILLS IN WRN SD. SOME WRF MODELS
INDICATE THIS AREA ORGANIZING MUCH LIKE LAST EVENING AND MOVING
EAST-NORTHEAST INTO SE ND-WCNTRL MN OVERNIGHT. SO VARIOUS
SCENERIOS TO PLAY OUT.
OVERALL WOULD EXPECT ORGANIZATION OF SOME ACTIVITY THIS EVE IN
ND/SD/MN BORDER REGIONS AND THEN SPREAD NORTH AND EAST TONIGHT SO
WILL STICK WITH HIGH POPS TONIGHT THOUGH CONFIDENCE AT ANY ONE
HOUR IS LOW. ALSO QPF AMOUNT IS NOT CERTAIN. PLUS ONLY AREA THAT
MUCH MORE THAN 1 INCH OF RAIN LAST NIGHT WAS EASTERN OTTER TAIL
COUNTY WITH 0.50 TO 1 INCH NRN WILKIN-SE CLAY INTO WADENA
COUNTIES. THIS AREA COULD TAKE THE RAIN. OTHERWISE...RAIN AMOUNTS
IN THE VALLEY WERE MOSTLY 0.50 OR LESS WITH A FEW EXCEPTIONS. WITH
UNCERTAINITY IN HOW THINGS WILL PLAY OUT TONIGHT DID NOT FEEL
CONFIDENT IN ISSUING ANY FLASH FLOOD WATCHES FOR OUR FCST AREA.
MODELS ACTUALLY BRING IN HIGHER PWAT (1.6) INTO AREA SUN AFTN-NIGH IN
GENERAL RAINFALL AROUND THE UPPER LOW IN SD AND THIS IS IN WHEN
MOST WIDESPREAD HEAVIER RAINFALL MAY OCCUR. THUS IF TRUE...GIVES
US TIME TO SEE WHAT FALLS THIS EVE BEFORE ISSUING ANY HEADLINES.
KEPT HIGH POPS SUNDAY INTO SUN NIGHT MOST ALL AREAS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 300 PM CDT SAT MAY 18 2013
UPR LOW AND SFC LOW WILL BE OVER SRN SD MONDAY INTO TUESDAY WITH
MOISTURE WRAPPING AROUND INTO ND/NW MN MON-TUES PERIOD WITH
GENERAL RAINFALL. KEPT POPS HIGH.
FOR TUESDAY NIGHT-FRIDAY...MODELS HAVE BEEN MOST CONSISTENT IN
BEGINNING TO MOVE THE STACKED NRN PLAINS LOW PRESSURE SYSTEM EWD
IN THE MID WEEK PERIOD. TUESDAY NIGHT INTO WEDNESDAY SHOWS THE
TAPPERING OFF OF VERY LIGHT RAIN WITH PERSISTENT NORTH-EASTERLY
BLAYER WINDS. INTRUDING DRY AIR FROM WRN ONT SHUD LEAD TO MARKEDLY
DIMINISHING CLOUD CLOVER WED EVENING. INCREASING HIGH PRESSURE
OVER WRN ONT AND THE LK SUPERIOR AREA ON THURS AND FRI SHUD SWING
WINDS FROM THE SOOUH EAST AND KEEP AN OVERALL DRYING AIRMASS OVR
THE RRV AND MOST OF MINNESOTA. A WARMIG RIDGE ALOFT AND INCREASED
LOW PRESSURE IN EASTERN MT DOES INCREASE THE RISK FOR SCT SHOWERS
AND TSTMS INTO EASTERN ND BY LATE FRIDAY AND ACROSS THE FA BY
SATURDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1153 PM CDT SAT MAY 18 2013
LIFR AFFECTING KBJI SHOULD IMPROVE BY SUNRISE.
OTHERWISE...INCREASING CHANCES FOR SHOWERS AND
THUNDERSTORMS...ALONG WITH LOWERING CIGS WILL BE THE MAIN CONCERN.
&&
.HYDROLOGY...
ISSUED AT 300 PM CDT SAT MAY 18 2013
WHEN NCRFC RAN THE MODEL TODAY USING 24 HOUR QPF IT BROUGHT SEVERAL
POINTS ABOVE FLOOD STAGE. THESE INCLUDE FARGO/SABIN/DILWORTH/HAWLEY
AND HENDRUM. SINCE THESE RISES ARE BASED ON FORECAST PCPN WENT AHEAD
AND ISSUED A RIVER POINT FLOOD WATCH FOR THESE 5 POINTS. THE FORECAST
QPF ALSO BROUGHT WAHPETON/EAST GRAND FORKS AND OSLO BACK ABOVE
ACTION STAGE SO ISSUED RIVER STATEMENTS ON THESE. ONLY DRAYTON AND
PEMBINA REMAIN IN A FLOOD STATEMENT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...RIDDLE
LONG TERM...RIDDLE/GUST
AVIATION...TG
HYDROLOGY...GODON
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
943 PM EDT MON MAY 20 2013
.SYNOPSIS...
UPPER RIDGE ALOFT TONIGHT. AFTERNOON CONVECTION TUESDAY AND
WEDNESDAY. COLD FRONT APPROACHES WEDNESDAY AND MOVES ACROSS
THURSDAY. COOLER HIGH PRESSURE FRIDAY AND THE WEEKEND.
&&
.NEAR TERM /THROUGH TUESDAY/...
INTRODUCE AREAS OF FOG MAINLY OVER AREAS THAT RECEIVED RAIN DURING
THE AFTERNOON HOURS...AND OVER TYGART RIVER AND KANAWHA RIVER
VALLEYS...AND THE SOUTHERN COAL FIELDS OF WEST VIRGINIA DURING THE
PREDAWN HOURS. ADJUSTED HOURLY TEMPS CURVE. REMOVED ALL PCPN
THROUGH 12Z TUESDAY. MODELS SHOWING NO DISTURBANCES AT H5 WITHIN UPPER
RIDGE ACROSS NORTHEAST KY...OH...WV...AND PA. FOR
TUESDAY...AFTERNOON SHOWERS AND STORMS ARE POSSIBLE.
PREVIOUS DISCUSSION BELOW...
RADAR IMAGERY AT 18Z SHOWING SHOWERS WITH A FEW EMBEDDED
THUNDERSTORMS MAINLY CONFINED TO THE EASTERN HIGHER TERRAIN AT
THIS POINT. EXPECT THIS PRECIP TO CONTINUE EASTWARD AS THE S/W
TROUGH AND ASSOC VORT MAX RESPONSIBLE FOR TODAY/S PRECIP CONTINUES
EAST AS WELL. LATEST SFC OBS AND RUC13 CONTINUE TO DEPICT SOME SFC
CONVERGENCE WITH WEAK TROUGH ACROSS THE FAR WESTERN ZONES THIS
AFTERNOON. BEST LLVL MOISTURE HAS PUSHED EASTWARD AND NEAR-TERM
CONVECTIVE MODELS DO NOT SHOW ANY REDEVELOPMENT ACROSS THE WEST.
WILL HOWEVER GO AHEAD AND CONTINUE A SLIGHT CHANCE FOR CONVECTION
OUT HERE WITH JUST A PINCH OF LLVL MOISTURE STILL NOTED ON POINT
SOUNDINGS AND PWATS UP AROUND 1.2-1.4 INCHES.
DURING THE OVERNIGHT HOURS TODAY/S S/W TROUGH AND VORT MAX CONTINUE
EASTWARD. PRECIP WILL HAVE ENDED FOR MOST IF NOT ALL LOCATIONS BTWN
00Z-03Z TUE. MOST LOCATIONS WILL REMAIN PRECIP-FREE OVERNIGHT BUT
LATEST NWP GUIDANCE DEPICTING A 2-3KFT LAYER OF CONVECTIVE MOISTURE
PUSHING INTO THE NORTHERN ZONES CENTERED AROUND 850MB AND AROUND 12Z
TUE. SIMULTANEOUSLY 850MB CONVERGENCE NOTED ACROSS THE I-79 CORRIDOR
AS WELL AND THUS WILL BRING IN SLIGHT CHANCE POPS WITH THUNDER WITH
THIS FEATURE. INHERITED MINS IN THE LOW/MID 60S MOST LOWLAND
LOCATIONS LOOK GOOD. WILL CONTINUE TO CARRY AT LEAST A SLIGHT CHANCE
OF SHOWERS/THUNDER MOST LOCATION DURING THE DAY...BUT THE BETTER
CHANCE OF THUNDERSTORMS ARRIVES SE OHIO ZONES BY AND AFTER 21Z AS
BETTER LLVL MOISTURE ARRIVES WITH DECENT SFC CONVERGENCE NOTED SAME
AREA. SHEAR IS WEAK AND THUS ORGANIZATION WILL BE AS WELL WITH
REGARD TO SEVERE POTENTIAL. BUT HEAVY DOWNPOURS WILL BE POSSIBLE AND
WITH SOME STRONG WINDS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
MAIN WEATHER MAKER THROUGH THE SHORT TERM WILL BE THE SURFACE COLD
FRONT PASSING WEDNESDAY...AND THEN THE LINGER UPPER LEVEL TROUGH.
FOR TUESDAY NIGHT...MAIN FOCUS IS TO THE WEST...SO DECREASED POPS
SOME...HOWEVER WITH LOTS OF MOISTURE STILL HANGING AROUND COULD NOT
GO DRY SO HAVE SLIGHT CHANCE TO CHANCE POPS FOR MUCH OF THE AREA
OVERNIGHT. COLD FRONT APPROACHES FROM THE WEST WEDNESDAY...WILL
LIKELY BE ONGOING CONVECTION/OUTFLOW BOUNDARIES TO OUR WEST
WEDNESDAY MORNING. WE SHOULD HAVE PLENTY OF INSTABILITY IN THE
WARM SECTOR AHEAD OF THE FRONT...NAM IS SHOWING 2000+ J/KG CAPE
ALONG THE OHIO RIVER AROUND NOON...WITH 30-40KTS BULK SHEER AND
PWATS AROUND 1.5 INCHES. SHOULD SEE A ROUND OF ORGANIZED
CONVECTION OUT AHEAD OF THE COLD FRONT MOVING FROM WEST TO EAST
ACROSS THE CWA. THE MOST LIKELY AREA OF CONCERN FOR STRONG TO
SEVERE STORMS CONTINUES TO BE ALONG AND EITHER SIDE OF THE OHIO
RIVER FROM SE OHIO INTO NORTH CENTRAL WEST VIRGINIA. WILL CONTINUE
HWO MENTION FOR DAMAGING WINDS AND HAIL POTENTIAL. THE ACTUAL COLD
FRONT WILL NOT PASS UNTIL THURSDAY...SO POPS CONTINUE THROUGH THE
SHORT TERM PERIOD.
WEDNESDAY WILL BE A WARM DAY...BUT WITH PLENTY OF CLOUDS SHOULD NOT
BE AS WARM AS TUESDAY. THURSDAY WILL BE ABOUT 10 DEGREES COOLER.
OVERNIGHT LOWS WILL BE MILD WITH LOTS OF CLOUDS AND MOISTURE.
BASED ON RECENT VERIFICATION STATS...BLENDED IN BIAS- CORRECTED
CONSENSUS GUIDANCE FOR BOTH HIGHS AND LOWS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HAVE GENERALLY FOLLOWED WPC THINKING FOR THIS PORTION OF THE FORECAST.
COLD FRONT SHOULD BE LOCATED SOUTHEAST OF THE REGION AT THE
BEGINNING OF THE PERIOD...WITH HIGH PRESSURE BUILDING IN. CHANCE
OF SHOWERS AND STORMS WILL END FROM THE NORTHWEST THURSDAY NIGHT
INTO FRIDAY. HOWEVER...A MID-LEVEL DISTURBANCE MOVING SOUTHEAST
WILL INCREASE THE CHANCES FOR PRECIPITATION ON FRIDAY....MAINLY IN
THE MOUNTAINS AND ADJACENT COUNTIES.
HIGH PRESSURE WILL THEN BE IN CONTROL OF THE AREA INTO MONDAY.
HOWEVER...A WEAK MID-LEVEL DISTURBANCE WILL SLIDE SOUTHEAST SATURDAY
NIGHT INTO SUNDAY.
A WARM FRONT WILL DEVELOP AND APPROACH THE REGION ON MONDAY. ECMWF
SUGGESTS THERE WILL BE A CHANCE OF SHOWERS AND STORMS MONDAY
AFTERNOON...ESPECIALLY ACROSS THE SOUTH. BECAUSE OF UNCERTAINTY...HAVE
LEFT THESE CHANCES OUT OF THE FORECAST FOR NOW.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH AT LEAST MIDNIGHT. MVFR LOW
STRATUS OR IFR FOG MAY DEVELOP ALONG CENTRAL AND SOUTHERN WESTERN
SLOPES OF THE APPALACHIANS WHERE IT RAINED DURING THE AFTERNOON
HOURS. IFR FOG IS LIKELY TO DEVELOP ALONG THE TYGART RIVER BASIN
INCLUDING EKN OVERNIGHT INTO EARLY TUESDAY MORNING. PERIODS OF
IFR/LIFR FOG WILL ALSO BE POSSIBLE ALONG THE KANAWHA AND ELK RIVER
VALLEYS TOWARD DAWN.
VFR CONDITIONS WILL RETURN TUESDAY MORNING...WITH AFTERNOON IFR
CONDITIONS UNDER HEAVY RAIN CAUSED BY ISOLATED TO SCATTERED SHOWERS OR
STORMS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z
WEDNESDAY...
FORECAST CONFIDENCE...HIGH.
ALTERNATE SCENARIOS: SOME UNCERTAINTY ON FOG DENSITY...LOW STRATUS...AND
AREAL COVERAGE OVERNIGHT AND EARLY MORNING TUESDAY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 05/21/13
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H L L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H M M H
AFTER 00Z WEDNESDAY...
IFR CONDITIONS POSSIBLE WEDNESDAY WITH SHOWERS AND THUNDERSTORMS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/ARJ/50
NEAR TERM...ARJ/50
SHORT TERM...MZ
LONG TERM...JSH
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
134 PM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING. A WARM FRONT WILL
THEN LIFT NORTH OF THE REGION TONIGHT AS A MID LEVEL RIDGE BUILDS
INTO THE REGION. A VERY WARM AND MOIST AIRMASS WILL ESTABLISH
ITSELF ACROSS THE AREA IN THE WAKE OF THE WARM FRONT FOR MONDAY
AND TUESDAY. THE THREAT OF SHOWERS AND THUNDERSTORMS WILL INCREASE
ONCE AGAIN BY TUESDAY AS THE MID LEVEL RIDGE PUSHES EAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
PESKY UPR LVL DISTURBANCE OVER THE OHIO RIVER VALLEY WILL PUSH
SLOWLY SOUTHEAST THROUGH THIS EVENING AS A MID LVL RIDGE BUILDS IN
BEHIND IT LATER TONIGHT. THE PROXIMITY OF THIS FEATURE ALONG WITH
DAYTIME HEATING WILL ALLOW SHOWERS AND THUNDERSTORMS TO POP ONCE
AGAIN. RAP NAM AND GFS ARE IN GOOD AGREEMENT IN TERMS OF QPF AROUND
A TENTH OF AN INCH OVER THE EASTERN PART OF THE CWA WHILE THE
ECMWF SHOWS ABOUT HALF THAT AMOUNT. COVERAGE SHOULD BE LESS THAN
YESTERDAY WITH THE HIGHEST CHANCES EXPECTED ACRS OUR SOUTHEAST.
ANY LINGERING SHOWERS AND STORMS THIS EVENING SHOULD DISSIPATE AS
MID LEVEL RIDGE BUILDS INTO THE REGION. HOWEVER...MODELS CONTINUE
TO INDICATE THAT AN IMPLIED WARM FRONT WILL LIFT NORTH ACRS THE
REGION LATE TONIGHT. AT THIS TIME WILL KEEP THE FORECAST
DRY...ALTHOUGH THERE ARE SOME SIGNALS THAT AN ISOLATED SHOWER OR
STORM COULD POP WITH ITS PASSAGE. HIGHS TODAY WILL RANGE FROM THE
LOWER TO MID 80S. LOWS TONIGHT WILL RANGE FROM THE LOWER TO MID
60S.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
MID LEVEL RIDGING ON MONDAY SHOULD GIVE OUR AREA A REPRIEVE FROM
SHOWER AND THUNDERSTORM ACTIVITY. A VERY WARM AND MOIST AIRMASS
WILL ESTABLISH ITSELF ACRS THE AREA IN THE WAKE OF THE WARM FRONT.
THUS...UNDER PARTLY TO MOSTLY SUNNY SKIES...TEMPERATURES SHOULD
WARM INTO THE UPPER 80S TO AROUND 90...WHICH IS MUCH ABOVE NORMAL
FOR LATE MAY. WITH DEWPOINTS IN THE MID AND UPPER 60S...IT WILL
ALSO FEEL QUITE HUMID.
FOR MONDAY NIGHT INTO TUESDAY...HAVE USED A BLEND OF THE 19.00Z
CMC AND THE 19.00Z ECMWF. THE GFS SUFFERS FROM CONVECTIVE FEED
BACK WHICH IS DIFFICULT TO USE. DURING THIS PERIOD...MID LEVEL
RIDGE MOVES EAST/SOUTHEAST. OUR AREA WILL BE LOCATED BETWEEN THIS
RIDGE AND A LARGE SCALE MID LVL CLOSED LOW OVER THE NRN/CNTRL
PLAINS. THE PROSPECTS OF SHOWERS/STORMS DURING THIS TIME FRAME
WILL DEPEND ON ANY EMBEDDED DISTURBANCES THAT MAY EJECT NE AROUND
THE SOUTHEAST SIDE OF THE LOW. HAVE ALLOWED POPS TO INCREMENTALLY
INCREASE. HIGHS ON TUESDAY WILL STILL BE VERY WARM...RANGING FROM
THE MID 80S TO AROUND 90.
FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...HAVE CONTINUED
WITH THE AFOREMENTIONED MODEL BLEND. IT LOOKS LIKE AS THE UPR LVL
CLOSED LOW SLOWLY MOVES EAST/SOUTHEAST TOWARD OUR REGION...A MORE
BONAFIDE S/WV AND SFC COLD FRONT WILL PUSH THROUGH THE REGION LATE
WEDNESDAY INTO THURSDAY. HAVE GONE WITH THE HIGHEST POPS DURING
THIS TIME FRAME DUE TO THESE FEATURES. TEMPERATURES WILL SHOW A
SLOW DOWNWARD TREND DURING THE PERIOD WITH THE INCREASE IN CLOUDS
AND THE THREAT FOR PCPN.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
A MID LEVEL TROUGH WILL PROGRESS SLOWLY EAST ACROSS THE REGION
THROUGH THE END OF THE WEEK. AN ASSOCIATED COLD FRONT WILL
CONTINUE TO PUSH EAST ON THURSDAY...FOLLOWED BY A SECONDARY COLD
FRONT THURSDAY NIGHT INTO FRIDAY. THIS WILL KEEP A CHANCE OF
THUNDERSTORMS GOING THROUGH THE DAY ON THURSDAY...WITH PCPN TAPERING
OFF TO SHOWERS BEHIND THE SECONDARY COLD FRONT THURSDAY NIGHT INTO
FRIDAY. A COOLER AIRMASS WILL PUSH INTO OUR AREA HEADING INTO THE
WEEKEND AS CANADIAN HIGH PRESSURE BUILDS IN FROM THE NORTH LATER
FRIDAY INTO SATURDAY. HIGHS ARE FORECAST TO RANGE FROM THE UPPER
60S TO THE LOWER 70S FRIDAY AND SATURDAY.
&&
.AVIATION /18Z SUNDAY THROUGH THURSDAY/...
SCATTERED SHOWERS HAVE DEVELOPED THIS AFTERNOON AS A WEAK
DISTURBANCE ENHANCES INSTABILITY ALONG AN OLD FRONTAL
BOUNDARY...MAINLY CLOSE TO EASTERN SITES ILN CMH AND LCK. SOME OF
THE SHOWERS MAY RESULT IN MVFR CONDITIONS. AN UPPER RIDGE WILL
BUILD IN TONIGHT WHICH WILL HELP TO BRING SHOWERS TO AN END. UNDER
CALM WINDS AND A HUMID AIRMASS...FG AND BR ARE EXPECTED TO REDUCE
VISIBILITIES TONIGHT. VFR CONDITIONS AND SOUTHERLY WINDS ARE
FORECAST AFTER 12Z MONDAY. MODELS PREDICT A MODERATE AMOUNT OF
INSTABILITY FOR MONDAY...BUT FORCING WILL BE WEAK SO KEPT SHOWERS
OUT OF THE FORECAST.
OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM TUESDAY THROUGH
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...CONIGLIO/HICKMAN
SHORT TERM...HICKMAN
LONG TERM...HICKMAN/JGL
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1042 AM EDT SUN MAY 19 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING. A WARM FRONT WILL
THEN LIFT NORTH OF THE REGION TONIGHT AS A MID LEVEL RIDGE BUILDS
INTO THE REGION. A VERY WARM AND MOIST AIRMASS WILL ESTABLISH
ITSELF ACROSS THE AREA IN THE WAKE OF THE WARM FRONT FOR MONDAY
AND TUESDAY. THE THREAT OF SHOWERS AND THUNDERSTORMS WILL INCREASE
ONCE AGAIN BY TUESDAY AS THE MID LEVEL RIDGE PUSHES EAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
PESKY UPR LVL DISTURBANCE OVER THE OHIO RIVER VALLEY WILL PUSH
SLOWLY SOUTHEAST THROUGH THIS EVENING AS A MID LVL RIDGE BUILDS IN
BEHIND IT LATER TONIGHT. THE PROXIMITY OF THIS FEATURE ALONG WITH
DAYTIME HEATING WILL ALLOW SHOWERS AND THUNDERSTORMS TO POP ONCE
AGAIN. RAP NAM AND GFS ARE IN GOOD AGREEMENT IN TERMS OF QPF AROUND
A TENTH OF AN INCH OVER THE EASTERN PART OF THE CWA WHILE THE
ECMWF SHOWS ABOUT HALF THAT AMOUNT. COVERAGE SHOULD BE LESS THAN
YESTERDAY WITH THE HIGHEST CHANCES EXPECTED ACRS OUR SOUTHEAST.
ANY LINGERING SHOWERS AND STORMS THIS EVENING SHOULD DISSIPATE AS
MID LEVEL RIDGE BUILDS INTO THE REGION. HOWEVER...MODELS CONTINUE
TO INDICATE THAT AN IMPLIED WARM FRONT WILL LIFT NORTH ACRS THE
REGION LATE TONIGHT. AT THIS TIME WILL KEEP THE FORECAST
DRY...ALTHOUGH THERE ARE SOME SIGNALS THAT AN ISOLATED SHOWER OR
STORM COULD POP WITH ITS PASSAGE. HIGHS TODAY WILL RANGE FROM THE
LOWER TO MID 80S. LOWS TONIGHT WILL RANGE FROM THE LOWER TO MID
60S.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
MID LEVEL RIDGING ON MONDAY SHOULD GIVE OUR AREA A REPRIEVE FROM
SHOWER AND THUNDERSTORM ACTIVITY. A VERY WARM AND MOIST AIRMASS
WILL ESTABLISH ITSELF ACRS THE AREA IN THE WAKE OF THE WARM FRONT.
THUS...UNDER PARTLY TO MOSTLY SUNNY SKIES...TEMPERATURES SHOULD
WARM INTO THE UPPER 80S TO AROUND 90...WHICH IS MUCH ABOVE NORMAL
FOR LATE MAY. WITH DEWPOINTS IN THE MID AND UPPER 60S...IT WILL
ALSO FEEL QUITE HUMID.
FOR MONDAY NIGHT INTO TUESDAY...HAVE USED A BLEND OF THE 19.00Z
CMC AND THE 19.00Z ECMWF. THE GFS SUFFERS FROM CONVECTIVE FEED
BACK WHICH IS DIFFICULT TO USE. DURING THIS PERIOD...MID LEVEL
RIDGE MOVES EAST/SOUTHEAST. OUR AREA WILL BE LOCATED BETWEEN THIS
RIDGE AND A LARGE SCALE MID LVL CLOSED LOW OVER THE NRN/CNTRL
PLAINS. THE PROSPECTS OF SHOWERS/STORMS DURING THIS TIME FRAME
WILL DEPEND ON ANY EMBEDDED DISTURBANCES THAT MAY EJECT NE AROUND
THE SOUTHEAST SIDE OF THE LOW. HAVE ALLOWED POPS TO INCREMENTALLY
INCREASE. HIGHS ON TUESDAY WILL STILL BE VERY WARM...RANGING FROM
THE MID 80S TO AROUND 90.
FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...HAVE CONTINUED
WITH THE AFOREMENTIONED MODEL BLEND. IT LOOKS LIKE AS THE UPR LVL
CLOSED LOW SLOWLY MOVES EAST/SOUTHEAST TOWARD OUR REGION...A MORE
BONAFIDE S/WV AND SFC COLD FRONT WILL PUSH THROUGH THE REGION LATE
WEDNESDAY INTO THURSDAY. HAVE GONE WITH THE HIGHEST POPS DURING
THIS TIME FRAME DUE TO THESE FEATURES. TEMPERATURES WILL SHOW A
SLOW DOWNWARD TREND DURING THE PERIOD WITH THE INCREASE IN CLOUDS
AND THE THREAT FOR PCPN.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
A MID LEVEL TROUGH WILL PROGRESS SLOWLY EAST ACROSS THE REGION
THROUGH THE END OF THE WEEK. AN ASSOCIATED COLD FRONT WILL
CONTINUE TO PUSH EAST ON THURSDAY...FOLLOWED BY A SECONDARY COLD
FRONT THURSDAY NIGHT INTO FRIDAY. THIS WILL KEEP A CHANCE OF
THUNDERSTORMS GOING THROUGH THE DAY ON THURSDAY...WITH PCPN TAPERING
OFF TO SHOWERS BEHIND THE SECONDARY COLD FRONT THURSDAY NIGHT INTO
FRIDAY. A COOLER AIRMASS WILL PUSH INTO OUR AREA HEADING INTO THE
WEEKEND AS CANADIAN HIGH PRESSURE BUILDS IN FROM THE NORTH LATER
FRIDAY INTO SATURDAY. HIGHS ARE FORECAST TO RANGE FROM THE UPPER
60S TO THE LOWER 70S FRIDAY AND SATURDAY.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
FG IS DISSIPATING WITH ALL SITES SOON TO BE IN THE VFR RANGE.
SCATTERED SHOWERS WILL DEVELOP THIS AFTERNOON AS A WEAK
DISTURBANCE ENHANCES INSTABILITY ALONG AN OLD FRONTAL
BOUNDARY...ESPECIALLY AT EASTERN SITES CMH AND LCK. AN UPPER RIDGE
WILL BUILD IN TONIGHT WHICH WILL HELP TO BRING SHOWERS TO AN END.
UNDER CALM WINDS AND A HUMID AIRMASS...BR IS EXPECTED TO REDUCE
VISIBILITIES TONIGHT. VFR CONDITIONS AND SOUTHERLY WINDS ARE
FORECAST FOR CVG AFTER 12Z MONDAY.
OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM TUESDAY THROUGH
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...CONIGLIO/HICKMAN
SHORT TERM...HICKMAN
LONG TERM...HICKMAN/JGL
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
919 PM CDT MON MAY 20 2013
.UPDATE...
JUST SOME MINOR CHANGES MADE TO THE FORECAST THIS EVENING.
EXPANDED HIGHER POPS TO THE EAST THROUGH THE OVERNIGHT HOURS AS
AREA OF RAIN CONTINUES TO SPIN OVER THE CWA. ALSO RAISED
TEMPERATURES A BIT OVERNIGHT AS CLOUD COVER SHOULD HINDER
TEMPERATURES FROM FALLING TOO MUCH. BREEZY WINDS ALREADY OCCURRING
ACROSS THE WEST...WHICH SHOULD ALSO AID IN KEEPING TEMPERATURES
UP.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY
AXIS OF SHOWERS HAS SHIFTED INTO THE EASTERN CWA THIS
AFTERNOON...WITH A BREAK FOR COUNTIES WEST OF ABERDEEN. THIS BREAK
WILL BE SHORT LIVED AS RADARS UPSTREAM IN NORTH DAKOTA ARE QUITE
ACTIVE...WITH WIDESPREAD LIGHT/MODERATE RAINFALL. HRRR AND RUC
GUIDANCE PIVOTS THIS MOISTURE BACK OVER THE CWA THIS EVENING AND
PERSISTS WELL INTO TUESDAY. MOST OF THE AREA HAS BEEN ABLE TO
HANDLE THE MOISTURE THUS FAR...WITH A FEW SPOTS REPORTING RISING
WATER IN DITCHES/CREEKS BUT NOT MUCH IMPACT OTHERWISE. SREF
PROBABILITIES FOR GREATER THEN A QUARTER INCH ARE HIGHEST ACROSS
OUR NORTHERN MISSOURI RIVER COUNTIES...AN AREA THAT HAS NOT
RECEIVED MUCH DROUGHT RELIEF THIS SPRING...AND THUS THINK THAT AREA
CAN HANDLE THE ADDITIONAL 1/2 INCH OF RAIN. SOILS FARTHER SOUTH
AND EAST MAY BE LESS FORGIVING AND WILL NEED TO BE MONITORED THIS
EVENING/OVERNIGHT FOR WATER ISSUES.
AS THE STACKED LOW CONTINUES TO DRIFT EAST TUESDAY...LIFT WEAKENS
WITH SOME DRIER AIR ENTRAINMENT RESULTING IN LOWER PROBABILITY FOR
PRECIPITATION AND QPF. TEMPERATURES THIS PERIOD WILL REMAIN BELOW
NORMAL AND CHANGE LITTLE THANKS TO CLOUD COVER.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
AS THE PERIOD OPENS...A DECAYING UPPER LOW CIRCULATION OVER THE
REGION WILL BE SLOWLY DRIFTING SOUTHEAST OUT OF THE AREA.
CONTINUED WRAP-AROUND MOISTURE COMBINED WITH SOME WEAK TROWALESQUE
FORCING/LIFT WILL KEEP POPS/RAIN SHOWERS MENTION GOING TUESDAY
NIGHT INTO WEDNESDAY AS THIS LOW PULLS AWAY FROM THE REGION.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT SHOULD BE DRY FORECAST
PERIODS WHILE A TRANSIENT HIGH-AMPLITUDE LONGWAVE HIGH PRESSURE
RIDGE WORKS THROUGH THE REGION.
BY FRIDAY...LOW LEVEL RETURN FLOW IS IN FULL SWING AND POPS FOR
SHOWERS AND THUNDERSTORMS MAKE THEIR RETURN TO THE FORECAST AS MID
AND UPPER LEVEL FLOW TAKES ON A RATHER PROLONGED PERIOD OF SWRLY
FLOW...THAT IS CURRENTLY PROGGED BY THE GFS AND ECMWF TO LAST
RIGHT INTO MONDAY.
THE COOLEST TEMPS DURING THE PERIOD LOOK TO BE TUESDAY NIGHT AND
WEDNESDAY BEFORE THE WARMING TREND ENSUES. BY THE
WEEKEND...TEMPERATURES SHOULD BE MUCH CLOSER TO CLIMO NORMAL.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
AN AREA OF RAIN WILL CONTINUE TO SPIN OVER MUCH OF CENTRAL AND
NORTHEASTERN SOUTH DAKOTA TONIGHT AND THROUGH THE DAY TUESDAY.
CIGS AND VSBYS WILL VARY BETWEEN VFR AND MVFR LEVELS WITH THE
RAINFALL. BREEZY NORTHERLY WINDS OF 20 TO 30 MPH WILL AFFECT KPIR
AND KMBG.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...PARKIN
SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
627 PM CDT MON MAY 20 2013
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY
AXIS OF SHOWERS HAS SHIFTED INTO THE EASTERN CWA THIS
AFTERNOON...WITH A BREAK FOR COUNTIES WEST OF ABERDEEN. THIS BREAK
WILL BE SHORT LIVED AS RADARS UPSTREAM IN NORTH DAKOTA ARE QUITE
ACTIVE...WITH WIDESPREAD LIGHT/MODERATE RAINFALL. HRRR AND RUC
GUIDANCE PIVOTS THIS MOISTURE BACK OVER THE CWA THIS EVENING AND
PERSISTS WELL INTO TUESDAY. MOST OF THE AREA HAS BEEN ABLE TO
HANDLE THE MOISTURE THUS FAR...WITH A FEW SPOTS REPORTING RISING
WATER IN DITCHES/CREEKS BUT NOT MUCH IMPACT OTHERWISE. SREF
PROBABILITIES FOR GREATER THEN A QUARTER INCH ARE HIGHEST ACROSS
OUR NORTHERN MISSOURI RIVER COUNTIES...AN AREA THAT HAS NOT
RECEIVED MUCH DROUGHT RELIEF THIS SPRING...AND THUS THINK THAT AREA
CAN HANDLE THE ADDITIONAL 1/2 INCH OF RAIN. SOILS FARTHER SOUTH
AND EAST MAY BE LESS FORGIVING AND WILL NEED TO BE MONITORED THIS
EVENING/OVERNIGHT FOR WATER ISSUES.
AS THE STACKED LOW CONTINUES TO DRIFT EAST TUESDAY...LIFT WEAKENS
WITH SOME DRIER AIR ENTRAINMENT RESULTING IN LOWER PROBABILITY FOR
PRECIPITATION AND QPF. TEMPERATURES THIS PERIOD WILL REMAIN BELOW
NORMAL AND CHANGE LITTLE THANKS TO CLOUD COVER.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
AS THE PERIOD OPENS...A DECAYING UPPER LOW CIRCULATION OVER THE
REGION WILL BE SLOWLY DRIFTING SOUTHEAST OUT OF THE AREA.
CONTINUED WRAP-AROUND MOISTURE COMBINED WITH SOME WEAK TROWALESQUE
FORCING/LIFT WILL KEEP POPS/RAIN SHOWERS MENTION GOING TUESDAY
NIGHT INTO WEDNESDAY AS THIS LOW PULLS AWAY FROM THE REGION.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT SHOULD BE DRY FORECAST
PERIODS WHILE A TRANSIENT HIGH-AMPLITUDE LONGWAVE HIGH PRESSURE
RIDGE WORKS THROUGH THE REGION.
BY FRIDAY...LOW LEVEL RETURN FLOW IS IN FULL SWING AND POPS FOR
SHOWERS AND THUNDERSTORMS MAKE THEIR RETURN TO THE FORECAST AS MID
AND UPPER LEVEL FLOW TAKES ON A RATHER PROLONGED PERIOD OF SWRLY
FLOW...THAT IS CURRENTLY PROGGED BY THE GFS AND ECMWF TO LAST
RIGHT INTO MONDAY.
THE COOLEST TEMPS DURING THE PERIOD LOOK TO BE TUESDAY NIGHT AND
WEDNESDAY BEFORE THE WARMING TREND ENSUES. BY THE
WEEKEND...TEMPERATURES SHOULD BE MUCH CLOSER TO CLIMO NORMAL.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
AN AREA OF RAIN WILL CONTINUE TO SPIN OVER MUCH OF CENTRAL AND
NORTHEASTERN SOUTH DAKOTA TONIGHT AND THROUGH THE DAY TUESDAY.
CIGS AND VSBYS WILL VARY BETWEEN VFR AND MVFR LEVELS WITH THE
RAINFALL. BREEZY NORTHERLY WINDS OF 20 TO 30 MPH WILL AFFECT KPIR
AND KMBG.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1123 AM CDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 1123 AM CDT SUN MAY 19 2013
PERSISTENT THETAE ADVECTION CONTINUES TO FILTER INTO OUR AREAS AT
THIS TIME GENERALLY ALONG AND EAST OF I 29. SURFACE OCCLUDED FRONT
PUSHED AS FAR EASTWARD AS A YANKTON TO HURON LINE BEFORE STALLING.
THEREFORE RAINFALL CONTINUES TO FILTER NORTHWARD AHEAD OF THE
OCCLUSION AND ALONG THE THETAE AXIS...AND COULD BE FAIRLY
PERSISTENT THROUGH THE AFTERNOON HOURS. FOR THE AFTERNOON HOURS...
HAVE HIGH POPS GOING IN OUR EASTERN ZONES...TAILING THEM OFF TO A
HIGH SCATTERED POP ALONG I 29...WITH LESS POPS TO THE WEST WHERE
SOME DRY SLOTTING HAS TAKEN HOLD BEHIND THE OCCLUSION. CURRENT
THOUGHTS ARE FOR SEVERE POTENTIAL...IS THAT IT WILL LIKELY BE
CONFINED TO OUR FAR EASTERN ZONES LATE TODAY OR THIS EVENING. THIS
IS DUE TO THE AMOUNT OF RAIN COOLED AIR WHICH WILL OCCUR IN OUR
EAST FOR THE NEXT FEW HOURS. THE FORECAST AREAS SHOT AT SEVERE
WEATHER WILL BE LIMITED IN THAT WHEN CELLS DO DECIDE TO FORM...A
QLCS WILL LIKELY QUICKLY FORM AND RUSH EASTWARD WHERE THE BEST
SHORT WAVE ENERGY IS. THEREFORE BELIEVE THAT THE WINDOW IS
NARROWING FOR A SEVERE WEATHER THREAT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 404 AM CDT SUN MAY 19 2013
UPPER LEVEL TROUGH DIGGING INTO THE HIGH PLAINS THIS MORNING WILL BE
THE CATALYST FOR ANOTHER ACTIVE WEATHER DAY ACROSS THE NORTHERN AND
CENTRAL PLAINS TODAY. THE TROUGH IS EXPECTED TO NUDGE EASTWARD
AND STRENGTHEN...WITH A CUT OFF FEATURE DEVELOPING OVER WESTERN
SOUTH DAKOTA BY THE AFTERNOON. LATEST ANALYSIS DEPICTS A SURFACE LOW
DEEPENING OVER CENTRAL SOUTH DAKOTA...WHICH IS EXPECTED TO SLOWLY
LIFT NORTH-NORTHEAST IN THE AFTERNOON. GENERALLY SOUTHERLY WINDS
WILL BEGIN TO SHIFT IN OUR WESTERN HALF LATE IN THE PERIOD. WITH
CONTINUED THETA-E ADVECTION THIS MORNING...ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL PERSIST THROUGHOUT THE FORECAST
AREA...HOWEVER BY LATE MORNING AND AFTERNOON...GREATER INSTABILITY
AND DYNAMICS WILL LEAD TO THE DEVELOPMENT OF MORE ORGANIZED
CONVECTION...ESPECIALLY ALONG AND EAST OF THE I-29 CORRIDOR.
DEWPOINTS ARE EXPECTED TO PERSIST IN THE LOW TO MID 60S HERE WHILE
THE AFTERNOON ARRIVAL OF THE BOUNDARY ALONG WITH AN UPPER LEVEL VORT
MAX AND SLIGHTLY BETTER SHEAR PROFILES...WILL CREATE THE BEST
POTENTIAL FOR STRONG TO SEVERE DEVELOPMENT. HOWEVER DESPITE ALL
THIS...THERE REMAINS QUITE A BIT OF UNCERTAINTY IN HOW THE ONGOING
PRECIPITATION ACROSS OUR EASTERN FORECAST AREA WILL AFFECT
CONVECTION LATER ON TODAY. ANY RESIDUAL OUTFLOW BOUNDARIES SETTING
UP ACROSS THE AREA COULD POTENTIALLY BECOME CONVECTION TRIGGERS
TODAY...HOWEVER REMNANT CLOUD COVERAGE IN THIS AREA MAY ALSO HAMPER
DAYTIME HEATING AND DESTABILIZATION A BIT. MAIN SEVERE THREAT WOULD
BE HAIL TO GOLFBALL SIZE AND WIND GUSTS TO 70 MPH...WITH A VERY LOW
TORNADO POTENTIAL MAINLY NEAR THE ADVANCING BOUNDARY.
THE SEVERE STORM THREAT WILL CONTINUE INTO THE EARLY EVENING...BUT
LIKELY IN A SOMEWHAT MORE ISOLATED MANNER...WITH EXCEPTIONS OF FAR
SOUTHEASTERN CWA WHERE ONGOING LINEAR MODE IS LIKELY FORCED BY THE
STRONG AFTERNOON PV ADVECTION. LAST FEW RUNS OF RAP HAVE NOT BEEN
QUITE AS BOISTEROUS WITH INSTABILITY IN PRE CONVECTIVE ENVIRONMENT
EARLY TO MID AFTERNOON... MAINLY 1500-2000 J/KG. SHEAR REMAINS
SOMEWHAT MARGINAL ACROSS THE AREA. DO SEE LOW LEVEL SHEAR VECTORS
SHOULD BE ORIENTED ALONG BOUNDARY BY 00Z...AND SHOULD BE
INCREASINGLY FAVORABLE FOR WIND MODE...WITH SOME HAIL IN STRONGER
UPDRAFTS TO PERHAPS HALF DOLLAR SIZE. WHILE LOW LEVEL JET WILL
BE WORKING TO VEER DURING THE EVENING...AREAS BETWEEN THE PRE
FRONTA/OUTFLOW CONVECTIVE LINE AND THE SYNOPTIC BOUNDARY COULD
STILL FIND AN ISOLATED STORM WITH MARGINALLY SEVERE CHARACTERICS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 404 AM CDT SUN MAY 19 2013
PRECIPITATION DISTRIBUTION BECOMES QUITE CHALLENGING AROUND WOBBLY
UPPER LOW WHICH BEGINS ITS JOURNEY ON MONDAY ACROSS NEBRASKA/SOUTH
DAKOTA...AND ENDS UP IN IOWA/MINNESOTA BY WEDNESDAY. VERY LITTLE
AGREEMENT ON TRACK OF CENTER...BETWEEN RUNS OR VARIOUS MODELS...
WHICH IS VERY PREDICTABLE GIVEN THE VARIOUS LOCATIONS OF WAVES
ROTATING AROUND THE FEATURE. WOULD MAKE SENSE FOR PATTERN TO
GRADUALLY BECOME SOMEWHAT MORE DIURNAL TOWARD LATER IN THE PERIOD.
WITH UPPER LOW TO WEST ON MONDAY...SHOULD BE A RELATIVELY QUIET
PERIOD UNTIL AT LEAST LATER IN THE DAY WITH INITIAL LARGER SCALE
FORCING LIFTING NORTH AND EAST EARLY IN THE DAY. LIKELY TO ACTUALLY
BREAK OUT SOMEWHAT ACROSS NORTHWEST IOWA AND ADJACENT LOCATIONS...
AND MODEST MIXING WOULD YIELD 75 TO 80 ACROSS THE AREA...AND MORE
OR LESS PUSHED MOST TEMPS UP AT LEAST A COUPLE DEGREES WITH LESS
WIDESPREAD PRECIPITATION EXPECTED. WILL FINALLY GET A BETTER
COVERAGE OF SHOWERS/ISOLATED THUNDER TOWARD CENTER OF UPPER WAVE
BY LATE AFTERNOON IN THE FAR WEST...AND DEVELOPMENT TOWARD LOWER
MISSOURI VALLEY ON CONVERGENCE AXIS. LOBE WILL WRAP NORTHWARD...
AND LIKELIHOOD FOR MORE SIGNIFICANT DEVELOPMENT ALONG
OUTFLOW/CONVERGENCE WELL TO THE EAST ON MONDAY NIGHT WILL SPELL
A QUICK DIMINISHMENT TO COVERAGE AGAIN OVERNIGHT...WITH EVEN
WESTERNMOST SHOWERS LIKELY BACKING FOR A TIME WESTWARD.
WHILE PERHAPS NOT QUITE AS MUCH CONCERN ON MONDAY...WITH OUTSIDE
CHANCE THAT AFTERNOON DESTABILIZATION COULD YIELD AN ISOLATED HAIL
OR WIND PRODUCING STORM ACROSS NORTHWEST IOWA...DO STILL HAVE SOME
STRONG CONCERN ABOUT TUESDAY AS POTENTIAL FUNNEL CLOUD/WEAK
TORNADIC SPINUP DAY. LIKELY THAT WILL GET SURFACE REFLECTION OF
UPPER WAVE SETTING UP AN ELONGATED EAST TO WEST LOW LEVEL
VORTICITY AXIS ACROSS THE CWA. SEVERAL FORECAST SOUNDINGS INDICATE
NOT ONLY POTENTIAL FOR 0-2KM SHEAR ON THE ORDER OF 15 KT...BUT
ALSO LIKELIHOOD OF GETTING A PRE CONVECTIVE 0-3KM CAPE OF 50-75
J/KG. WILL LIKELY GET DEEPER CONVECTION GOING GIVEN A 800-1200 J/KG
PRE CONVECTIVE ML CAPE WITH VERY LITTLE CAPPING...SO WILL NOT ONLY
DEVELOP FAIRLY EARLY IN THE DIURNAL CYCLE...BUT WILL LIKELY BE
INITIATED BY LATER MORNING OR MIDDAY WITH ALL MODELS SHOWING NICE
DIV Q WRAPPING UP THE EAST FLANK OF THE CYCLONE.
WITH ACTIVE SHORT TERM WEATHER...ONLY A CURSORY GLANCE INTO THE
LATE WEEK CONDITIONS FOR WEDNESDAY THROUGH SATURDAY. WEDNESDAY
WILL STILL FEEL IMPACT OF UPPER LOW...LIKELY THE COOLEST DAY...
AND ONE WHERE SHOWERS WILL START TO SHOW A DECREASE IN OVERALL
COVERAGE...BUT STRONGER THROUGH THE EAST WITH SOME LOWER LEVEL
FRONTOGENETIC SUPPORT ON BACK SIDE OF DEPARTING WAVE. FINALLY
DRIES OUT BY THURSDAY AND FRIDAY...AND ONLY SIGNIFICANT CHANGE
WAS TO ALLOW FOR SOME DRIER DEW POINTS AND COOLER FRIDAY LOWS
FOR THE EAST/NORTHEAST PORTIONS OF THE AREA WITH VERY DRY
TRAJECTORY OUT OF KEEWATIN HIGH...SOMETHING IMPORTANT TO CONSIDER
FOR FIRE WEATHER CONCERNS...AFTER SEVERAL DAYS OF SOGGY CONDITIONS
FOR PRESCRIBED BURN OPERATIONS EARLY IN THE WEEK. KEPT SOME LOWER
END POPS FOR FRIDAY NIGHT WEST...AND SATURDAY ACROSS THE AREA
WITH DEVELOPMENT OF WARM AIR ADVECTION AS UPPER RIDGE BEGINS TO
SHOW SIGNS OF BREAKING DOWN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 637 AM CDT SUN MAY 19 2013
INSTABILITY WILL LEAD TO SCATTERED SHOWERS AND THUNDERSTORMS THROUGH
18Z...WHICH WILL BECOME MORE WIDESPREAD EARLY AFTERNOON THROUGH MID
EVENING. BEST POTENTIAL FOR THUNDERSTORMS WILL BE ALONG AND EAST OF
I-29 THROUGH AROUND MID-EVENING OR 03Z. STRONG TO SEVERE STORMS WILL
BE POSSIBLE...WITH LARGE HAIL AND DAMAGING WIND THREATS.
PRECIPITATION WILL WEAKEN AND BECOME MORE ISOLATED TO SCATTERED AFTER
03Z. OTHERWISE WINDS WILL GENERALLY BE FROM THE SOUTH
SOUTHEAST...HOWEVER OUTFLOW BOUNDARIES FROM OVERNIGHT STORMS HAS
ALLOWED VARIABILITY THIS MORNING IN SOME AREAS. PATCHY LOW CEILINGS
IN THE NORTHEAST ARE EXPECTED TO LIFT WITHIN THE NEXT FEW HOURS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...MJF
SHORT TERM... /CHAPMAN
LONG TERM...CHAPMAN
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
646 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 404 AM CDT SUN MAY 19 2013
UPPER LEVEL TROUGH DIGGING INTO THE HIGH PLAINS THIS MORNING WILL BE
THE CATALYST FOR ANOTHER ACTIVE WEATHER DAY ACROSS THE NORTHERN AND
CENTRAL PLAINS TODAY. THE TROUGH IS EXPECTED TO NUDGE EASTWARD
AND STRENGTHEN...WITH A CUT OFF FEATURE DEVELOPING OVER WESTERN
SOUTH DAKOTA BY THE AFTERNOON. LATEST ANALYSIS DEPICTS A SURFACE LOW
DEEPENING OVER CENTRAL SOUTH DAKOTA...WHICH IS EXPECTED TO SLOWLY
LIFT NORTH-NORTHEAST IN THE AFTERNOON. GENERALLY SOUTHERLY WINDS
WILL BEGIN TO SHIFT IN OUR WESTERN HALF LATE IN THE PERIOD. WITH
CONTINUED THETA-E ADVECTION THIS MORNING...ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL PERSIST THROUGHOUT THE FORECAST
AREA...HOWEVER BY LATE MORNING AND AFTERNOON...GREATER INSTABILITY
AND DYNAMICS WILL LEAD TO THE DEVELOPMENT OF MORE ORGANIZED
CONVECTION...ESPECIALLY ALONG AND EAST OF THE I-29 CORRIDOR.
DEWPOINTS ARE EXPECTED TO PERSIST IN THE LOW TO MID 60S HERE WHILE
THE AFTERNOON ARRIVAL OF THE BOUNDARY ALONG WITH AN UPPER LEVEL VORT
MAX AND SLIGHTLY BETTER SHEAR PROFILES...WILL CREATE THE BEST
POTENTIAL FOR STRONG TO SEVERE DEVELOPMENT. HOWEVER DESPITE ALL
THIS...THERE REMAINS QUITE A BIT OF UNCERTAINTY IN HOW THE ONGOING
PRECIPITATION ACROSS OUR EASTERN FORECAST AREA WILL AFFECT
CONVECTION LATER ON TODAY. ANY RESIDUAL OUTFLOW BOUNDARIES SETTING
UP ACROSS THE AREA COULD POTENTIALLY BECOME CONVECTION TRIGGERS
TODAY...HOWEVER REMNANT CLOUD COVERAGE IN THIS AREA MAY ALSO HAMPER
DAYTIME HEATING AND DESTABILIZATION A BIT. MAIN SEVERE THREAT WOULD
BE HAIL TO GOLFBALL SIZE AND WIND GUSTS TO 70 MPH...WITH A VERY LOW
TORNADO POTENTIAL MAINLY NEAR THE ADVANCING BOUNDARY.
THE SEVERE STORM THREAT WILL CONTINUE INTO THE EARLY EVENING...BUT
LIKELY IN A SOMEWHAT MORE ISOLATED MANNER...WITH EXCEPTIONS OF FAR
SOUTHEASTERN CWA WHERE ONGOING LINEAR MODE IS LIKELY FORCED BY THE
STRONG AFTERNOON PV ADVECTION. LAST FEW RUNS OF RAP HAVE NOT BEEN
QUITE AS BOISTEROUS WITH INSTABILITY IN PRE CONVECTIVE ENVIRONMENT
EARLY TO MID AFTERNOON... MAINLY 1500-2000 J/KG. SHEAR REMAINS
SOMEWHAT MARGINAL ACROSS THE AREA. DO SEE LOW LEVEL SHEAR VECTORS
SHOULD BE ORIENTED ALONG BOUNDARY BY 00Z...AND SHOULD BE
INCREASINGLY FAVORABLE FOR WIND MODE...WITH SOME HAIL IN STRONGER
UPDRAFTS TO PERHAPS HALF DOLLAR SIZE. WHILE LOW LEVEL JET WILL
BE WORKING TO VEER DURING THE EVENING...AREAS BETWEEN THE PRE
FRONTA/OUTFLOW CONVECTIVE LINE AND THE SYNOPTIC BOUNDARY COULD
STILL FIND AN ISOLATED STORM WITH MARGINALLY SEVERE CHARACTERICS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 404 AM CDT SUN MAY 19 2013
PRECIPITATION DISTRIBUTION BECOMES QUITE CHALLENGING AROUND WOBBLY
UPPER LOW WHICH BEGINS ITS JOURNEY ON MONDAY ACROSS NEBRASKA/SOUTH
DAKOTA...AND ENDS UP IN IOWA/MINNESOTA BY WEDNESDAY. VERY LITTLE
AGREEMENT ON TRACK OF CENTER...BETWEEN RUNS OR VARIOUS MODELS...
WHICH IS VERY PREDICTABLE GIVEN THE VARIOUS LOCATIONS OF WAVES
ROTATING AROUND THE FEATURE. WOULD MAKE SENSE FOR PATTERN TO
GRADUALLY BECOME SOMEWHAT MORE DIURNAL TOWARD LATER IN THE PERIOD.
WITH UPPER LOW TO WEST ON MONDAY...SHOULD BE A RELATIVELY QUIET
PERIOD UNTIL AT LEAST LATER IN THE DAY WITH INITIAL LARGER SCALE
FORCING LIFTING NORTH AND EAST EARLY IN THE DAY. LIKELY TO ACTUALLY
BREAK OUT SOMEWHAT ACROSS NORTHWEST IOWA AND ADJACENT LOCATIONS...
AND MODEST MIXING WOULD YIELD 75 TO 80 ACROSS THE AREA...AND MORE
OR LESS PUSHED MOST TEMPS UP AT LEAST A COUPLE DEGREES WITH LESS
WIDESPREAD PRECIPITATION EXPECTED. WILL FINALLY GET A BETTER
COVERAGE OF SHOWERS/ISOLATED THUNDER TOWARD CENTER OF UPPER WAVE
BY LATE AFTERNOON IN THE FAR WEST...AND DEVELOPMENT TOWARD LOWER
MISSOURI VALLEY ON CONVERGENCE AXIS. LOBE WILL WRAP NORTHWARD...
AND LIKELIHOOD FOR MORE SIGNIFICANT DEVELOPMENT ALONG
OUTFLOW/CONVERGENCE WELL TO THE EAST ON MONDAY NIGHT WILL SPELL
A QUICK DIMINISHMENT TO COVERAGE AGAIN OVERNIGHT...WITH EVEN
WESTERNMOST SHOWERS LIKELY BACKING FOR A TIME WESTWARD.
WHILE PERHAPS NOT QUITE AS MUCH CONCERN ON MONDAY...WITH OUTSIDE
CHANCE THAT AFTERNOON DESTABILIZATION COULD YIELD AN ISOLATED HAIL
OR WIND PRODUCING STORM ACROSS NORTHWEST IOWA...DO STILL HAVE SOME
STRONG CONCERN ABOUT TUESDAY AS POTENTIAL FUNNEL CLOUD/WEAK
TORNADIC SPINUP DAY. LIKELY THAT WILL GET SURFACE REFLECTION OF
UPPER WAVE SETTING UP AN ELONGATED EAST TO WEST LOW LEVEL
VORTICITY AXIS ACROSS THE CWA. SEVERAL FORECAST SOUNDINGS INDICATE
NOT ONLY POTENTIAL FOR 0-2KM SHEAR ON THE ORDER OF 15 KT...BUT
ALSO LIKELIHOOD OF GETTING A PRE CONVECTIVE 0-3KM CAPE OF 50-75
J/KG. WILL LIKELY GET DEEPER CONVECTION GOING GIVEN A 800-1200 J/KG
PRE CONVECTIVE ML CAPE WITH VERY LITTLE CAPPING...SO WILL NOT ONLY
DEVELOP FAIRLY EARLY IN THE DIURNAL CYCLE...BUT WILL LIKELY BE
INITIATED BY LATER MORNING OR MIDDAY WITH ALL MODELS SHOWING NICE
DIV Q WRAPPING UP THE EAST FLANK OF THE CYCLONE.
WITH ACTIVE SHORT TERM WEATHER...ONLY A CURSORY GLANCE INTO THE
LATE WEEK CONDITIONS FOR WEDNESDAY THROUGH SATURDAY. WEDNESDAY
WILL STILL FEEL IMPACT OF UPPER LOW...LIKELY THE COOLEST DAY...
AND ONE WHERE SHOWERS WILL START TO SHOW A DECREASE IN OVERALL
COVERAGE...BUT STRONGER THROUGH THE EAST WITH SOME LOWER LEVEL
FRONTOGENETIC SUPPORT ON BACK SIDE OF DEPARTING WAVE. FINALLY
DRIES OUT BY THURSDAY AND FRIDAY...AND ONLY SIGNIFICANT CHANGE
WAS TO ALLOW FOR SOME DRIER DEW POINTS AND COOLER FRIDAY LOWS
FOR THE EAST/NORTHEAST PORTIONS OF THE AREA WITH VERY DRY
TRAJECTORY OUT OF KEEWATIN HIGH...SOMETHING IMPORTANT TO CONSIDER
FOR FIRE WEATHER CONCERNS...AFTER SEVERAL DAYS OF SOGGY CONDITIONS
FOR PRESCRIBED BURN OPERATIONS EARLY IN THE WEEK. KEPT SOME LOWER
END POPS FOR FRIDAY NIGHT WEST...AND SATURDAY ACROSS THE AREA
WITH DEVELOPMENT OF WARM AIR ADVECTION AS UPPER RIDGE BEGINS TO
SHOW SIGNS OF BREAKING DOWN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 637 AM CDT SUN MAY 19 2013
INSTABILITY WILL LEAD TO SCATTERED SHOWERS AND THUNDERSTORMS THROUGH
18Z...WHICH WILL BECOME MORE WIDESPREAD EARLY AFTERNOON THROUGH MID
EVENING. BEST POTENTIAL FOR THUNDERSTORMS WILL BE ALONG AND EAST OF
I-29 THROUGH AROUND MID-EVENING OR 03Z. STRONG TO SEVERE STORMS WILL
BE POSSIBLE...WITH LARGE HAIL AND DAMAGING WIND THREATS.
PRECIPITATION WILL WEAKEN AND BECOME MORE ISOLATED TO SCATTERED AFTER
03Z. OTHERWISE WINDS WILL GENERALLY BE FROM THE SOUTH
SOUTHEAST...HOWEVER OUTFLOW BOUNDARIES FROM OVERNIGHT STORMS HAS
ALLOWED VARIABILITY THIS MORNING IN SOME AREAS. PATCHY LOW CEILINGS
IN THE NORTHEAST ARE EXPECTED TO LIFT WITHIN THE NEXT FEW HOURS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM... /CHAPMAN
LONG TERM...CHAPMAN
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
455 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 404 AM CDT SUN MAY 19 2013
UPPER LEVEL TROUGH DIGGING INTO THE HIGH PLAINS THIS MORNING WILL BE
THE CATALYST FOR ANOTHER ACTIVE WEATHER DAY ACROSS THE NORTHERN AND
CENTRAL PLAINS TODAY. THE TROUGH IS EXPECTED TO NUDGE EASTWARD
AND STRENGTHEN...WITH A CUT OFF FEATURE DEVELOPING OVER WESTERN
SOUTH DAKOTA BY THE AFTERNOON. LATEST ANALYSIS DEPICTS A SURFACE LOW
DEEPENING OVER CENTRAL SOUTH DAKOTA...WHICH IS EXPECTED TO SLOWLY
LIFT NORTH-NORTHEAST IN THE AFTERNOON. GENERALLY SOUTHERLY WINDS
WILL BEGIN TO SHIFT IN OUR WESTERN HALF LATE IN THE PERIOD. WITH
CONTINUED THETA-E ADVECTION THIS MORNING...ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL PERSIST THROUGHOUT THE FORECAST
AREA...HOWEVER BY LATE MORNING AND AFTERNOON...GREATER INSTABILITY
AND DYNAMICS WILL LEAD TO THE DEVELOPMENT OF MORE ORGANIZED
CONVECTION...ESPECIALLY ALONG AND EAST OF THE I-29 CORRIDOR.
DEWPOINTS ARE EXPECTED TO PERSIST IN THE LOW TO MID 60S HERE WHILE
THE AFTERNOON ARRIVAL OF THE BOUNDARY ALONG WITH AN UPPER LEVEL VORT
MAX AND SLIGHTLY BETTER SHEAR PROFILES...WILL CREATE THE BEST
POTENTIAL FOR STRONG TO SEVERE DEVELOPMENT. HOWEVER DESPITE ALL
THIS...THERE REMAINS QUITE A BIT OF UNCERTAINTY IN HOW THE ONGOING
PRECIPITATION ACROSS OUR EASTERN FORECAST AREA WILL AFFECT
CONVECTION LATER ON TODAY. ANY RESIDUAL OUTFLOW BOUNDARIES SETTING
UP ACROSS THE AREA COULD POTENTIALLY BECOME CONVECTION TRIGGERS
TODAY...HOWEVER REMNANT CLOUD COVERAGE IN THIS AREA MAY ALSO HAMPER
DAYTIME HEATING AND DESTABILIZATION A BIT. MAIN SEVERE THREAT WOULD
BE HAIL TO GOLFBALL SIZE AND WIND GUSTS TO 70 MPH...WITH A VERY LOW
TORNADO POTENTIAL MAINLY NEAR THE ADVANCING BOUNDARY.
THE SEVERE STORM THREAT WILL CONTINUE INTO THE EARLY EVENING...BUT
LIKELY IN A SOMEWHAT MORE ISOLATED MANNER...WITH EXCEPTIONS OF FAR
SOUTHEASTERN CWA WHERE ONGOING LINEAR MODE IS LIKELY FORCED BY THE
STRONG AFTERNOON PV ADVECTION. LAST FEW RUNS OF RAP HAVE NOT BEEN
QUITE AS BOISTEROUS WITH INSTABILITY IN PRE CONVECTIVE ENVIRONMENT
EARLY TO MID AFTERNOON... MAINLY 1500-2000 J/KG. SHEAR REMAINS
SOMEWHAT MARGINAL ACROSS THE AREA. DO SEE LOW LEVEL SHEAR VECTORS
SHOULD BE ORIENTED ALONG BOUNDARY BY 00Z...AND SHOULD BE
INCREASINGLY FAVORABLE FOR WIND MODE...WITH SOME HAIL IN STRONGER
UPDRAFTS TO PERHAPS HALF DOLLAR SIZE. WHILE LOW LEVEL JET WILL
BE WORKING TO VEER DURING THE EVENING...AREAS BETWEEN THE PRE
FRONTA/OUTFLOW CONVECTIVE LINE AND THE SYNOPTIC BOUNDARY COULD
STILL FIND AN ISOLATED STORM WITH MARGINALLY SEVERE CHARACTERICS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 404 AM CDT SUN MAY 19 2013
PRECIPITATION DISTRIBUTION BECOMES QUITE CHALLENGING AROUND WOBBLY
UPPER LOW WHICH BEGINS ITS JOURNEY ON MONDAY ACROSS NEBRASKA/SOUTH
DAKOTA...AND ENDS UP IN IOWA/MINNESOTA BY WEDNESDAY. VERY LITTLE
AGREEMENT ON TRACK OF CENTER...BETWEEN RUNS OR VARIOUS MODELS...
WHICH IS VERY PREDICTABLE GIVEN THE VARIOUS LOCATIONS OF WAVES
ROTATING AROUND THE FEATURE. WOULD MAKE SENSE FOR PATTERN TO
GRADUALLY BECOME SOMEWHAT MORE DIURNAL TOWARD LATER IN THE PERIOD.
WITH UPPER LOW TO WEST ON MONDAY...SHOULD BE A RELATIVELY QUIET
PERIOD UNTIL AT LEAST LATER IN THE DAY WITH INITIAL LARGER SCALE
FORCING LIFTING NORTH AND EAST EARLY IN THE DAY. LIKELY TO ACTUALLY
BREAK OUT SOMEWHAT ACROSS NORTHWEST IOWA AND ADJACENT LOCATIONS...
AND MODEST MIXING WOULD YIELD 75 TO 80 ACROSS THE AREA...AND MORE
OR LESS PUSHED MOST TEMPS UP AT LEAST A COUPLE DEGREES WITH LESS
WIDESPREAD PRECIPITATION EXPECTED. WILL FINALLY GET A BETTER
COVERAGE OF SHOWERS/ISOLATED THUNDER TOWARD CENTER OF UPPER WAVE
BY LATE AFTERNOON IN THE FAR WEST...AND DEVELOPMENT TOWARD LOWER
MISSOURI VALLEY ON CONVERGENCE AXIS. LOBE WILL WRAP NORTHWARD...
AND LIKELIHOOD FOR MORE SIGNIFICANT DEVELOPMENT ALONG
OUTFLOW/CONVERGENCE WELL TO THE EAST ON MONDAY NIGHT WILL SPELL
A QUICK DIMINISHMENT TO COVERAGE AGAIN OVERNIGHT...WITH EVEN
WESTERNMOST SHOWERS LIKELY BACKING FOR A TIME WESTWARD.
WHILE PERHAPS NOT QUITE AS MUCH CONCERN ON MONDAY...WITH OUTSIDE
CHANCE THAT AFTERNOON DESTABILIZATION COULD YIELD AN ISOLATED HAIL
OR WIND PRODUCING STORM ACROSS NORTHWEST IOWA...DO STILL HAVE SOME
STRONG CONCERN ABOUT TUESDAY AS POTENTIAL FUNNEL CLOUD/WEAK
TORNADIC SPINUP DAY. LIKELY THAT WILL GET SURFACE REFLECTION OF
UPPER WAVE SETTING UP AN ELONGATED EAST TO WEST LOW LEVEL
VORTICITY AXIS ACROSS THE CWA. SEVERAL FORECAST SOUNDINGS INDICATE
NOT ONLY POTENTIAL FOR 0-2KM SHEAR ON THE ORDER OF 15 KT...BUT
ALSO LIKELIHOOD OF GETTING A PRE CONVECTIVE 0-3KM CAPE OF 50-75
J/KG. WILL LIKELY GET DEEPER CONVECTION GOING GIVEN A 800-1200 J/KG
PRE CONVECTIVE ML CAPE WITH VERY LITTLE CAPPING...SO WILL NOT ONLY
DEVELOP FAIRLY EARLY IN THE DIURNAL CYCLE...BUT WILL LIKELY BE
INITIATED BY LATER MORNING OR MIDDAY WITH ALL MODELS SHOWING NICE
DIV Q WRAPPING UP THE EAST FLANK OF THE CYCLONE.
WITH ACTIVE SHORT TERM WEATHER...ONLY A CURSORY GLANCE INTO THE
LATE WEEK CONDITIONS FOR WEDNESDAY THROUGH SATURDAY. WEDNESDAY
WILL STILL FEEL IMPACT OF UPPER LOW...LIKELY THE COOLEST DAY...
AND ONE WHERE SHOWERS WILL START TO SHOW A DECREASE IN OVERALL
COVERAGE...BUT STRONGER THROUGH THE EAST WITH SOME LOWER LEVEL
FRONTOGENETIC SUPPORT ON BACK SIDE OF DEPARTING WAVE. FINALLY
DRIES OUT BY THURSDAY AND FRIDAY...AND ONLY SIGNIFICANT CHANGE
WAS TO ALLOW FOR SOME DRIER DEW POINTS AND COOLER FRIDAY LOWS
FOR THE EAST/NORTHEAST PORTIONS OF THE AREA WITH VERY DRY
TRAJECTORY OUT OF KEEWATIN HIGH...SOMETHING IMPORTANT TO CONSIDER
FOR FIRE WEATHER CONCERNS...AFTER SEVERAL DAYS OF SOGGY CONDITIONS
FOR PRESCRIBED BURN OPERATIONS EARLY IN THE WEEK. KEPT SOME LOWER
END POPS FOR FRIDAY NIGHT WEST...AND SATURDAY ACROSS THE AREA
WITH DEVELOPMENT OF WARM AIR ADVECTION AS UPPER RIDGE BEGINS TO
SHOW SIGNS OF BREAKING DOWN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 1030 PM CDT SAT MAY 18 2013
CONCERN OVER THE THIS TAF PERIOD CONTINUES TO BE FOR THE
THUNDERSTORM THREAT. IN GENERAL VFR CONDITIONS WILL PREVAIL THROUGH
THE PERIOD...ALTHOUGH REDUCTIONS TO MVFR AND BRIEFLY IFR CIGS/VIS IS
LIKELY IN ANY THUNDERSTORM. AREA OF SHOWERS AND THUNDERSTORMS ACROSS
NEBRASKA WILL CONTINUE TO EXPAND AND MOVE NORTHEAST INTO OUR AREA.
TIMING FROM THE 00Z TAF ISSUANCE STILL LOOKS IN GOOD SHAPE. THERE IS
A MARGINAL SEVERE THREAT WITH SOME OF THESE STORMS...WITH HAIL
AROUND QUARTER SIZE POSSIBLE...ALTHOUGH STRONG WINDS ARE THE BIGGEST
CONCERN...WITH GUSTS IN THE 40 TO 55 KT RANGE POSSIBLE IN SOME OF
THE STORMS. MOST OF THE ACTIVITY SHOULD EXIT BY MORNING. MAY HAVE
SOME FOG AND STRATUS DEVELOP BEHIND THE RAIN...BUT EXPECT THAT TO
LIFT BY MID TO LATE MORNING. ANOTHER ROUND OF SHOWERS AND STORMS IS
EXPECTED BY SUNDAY AFTERNOON. THIS ACTIVITY SHOULD FORM IN EASTERN
NEBRASKA AND MOVE NORTH NORTHEAST...PRIMARILY IMPACTING NORTHWEST
IOWA...SOUTHWEST MINNESOTA AND EXTREME SOUTHEAST SOUTH DAKOTA. HAIL
AND STRONG WINDS ARE ALSO POSSIBLE WITH THESE STORMS. BY EVENING
EXPECT MOST OF THE AREA BE TO COVERED BY SHOWERS AND
THUNDERSTORMS...AND WHILE THE SEVERE THREAT SHOULD BE LOWER...GUSTY
WINDS AND HAIL ARE STILL A POSSIBILITY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM... /CHAPMAN
LONG TERM...CHAPMAN
AVIATION...CHENARD
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
854 PM CDT MON MAY 20 2013
.UPDATE...
HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO REFLECT CLEAR SKIES
ACROSS THE MID STATE THRU THE EVENING HRS...WITH A GENERAL INCREASE
OF CLOUDINESS WEST TO EAST ACROSS THE MID STATE AFTER MIDNIGHT. HAVE
ALSO MENTIONED PATCHY FOG AFTER MIDNIGHT PLATEAU PER CONTINUED LOW
LEVEL MOISTURE POOLING POTENTIAL. WITH SOME UNCERTAINTIES CONCERNING
ACTUAL CLOUD COVERAGE LATE...WILL CONTINUE TO GO CLOSE TO CURRENT
FORECAST REASONING ON OVERNIGHT LOWS.
&&
.PREV DISCUSSION.../ISSUED 603 PM CDT MON MAY 20 2013/
UPDATE...FOR AVIATION.
AVIATION...
00Z TAFS...UPPER LEVEL RIDGE WILL CONTINUE TO BE THE MAIN
INFLUENCE WITH FAIR WX THROUGH THIS EVENING. SOME MVFR BR OR
PERHAPS PATCHY STRATUS IS POSSIBLE TOWARD DAYBREAK. S WINDS WILL
BECOME SOMEWHAT GUSTY ON TUESDAY...TO 20KT AT TIMES...ESPECIALLY
FOR CKV. THE RIDGE WILL BEGIN TO MOVE EAST WITH AN APPROACHING
DISTURBANCE BRINGING A CHANCE FOR TSRA BY THE END OF THE PERIOD.
COVERAGE WILL BE GENERALLY ISOLD...BUT COVERAGE WILL BE INCREASING
FROM THE WEST...SO INCLUDING A VCTS FOR CKV AFTER 21Z.
13
PREV DISCUSSION... /ISSUED 324 PM CDT MON MAY 20 2013/
AFTERNOON CU DEVELOPMENT IS WIDESPREAD ACROSS THE MID STATE THIS
AFTERNOON AS DEWPOINTS HAVE CONTINUED TO RISE. MID LEVEL CAP IS
RATHER STRONG ACCORDING TO THE 12Z SOUNDING FROM THIS MORNING. THE
HIGHER DEWPOINTS HAVE ACTED TO LOWER CONVECTIVE TEMPS BUT CURRENT
TEMPS ARE STRUGGLING TO RISE GIVEN THE EXTRA CLOUD COVER.
FOR TONIGHT`S FORECAST...WILL INCLUDE A 20 POP BUT ONLY FOR THE
NW. THIS IS IN LINE WITH THE HRRR REFLECTIVITY FCST WHICH SHOWS
LITTLE IF ANY DEVELOPMENT. OVERALL...IT JUST APPEARS THAT THERE IS
TOO MUCH VERTICAL DRYNESS IN PLACE.
A SLIGHT CHANCE OF SHOWERS AND TSTMS WILL BE IN THE FCST AGAIN FOR
TUESDAY. MOISTURE LEVELS SHOULD BE HIGHER AND WE DO SEE MORE 18Z CAP
EROSION WITH THE GFS MODEL. THE INCREASE IN MOISTURE WILL BE AIDED
BY AN APPROACHING FRONTAL BOUNDARY WHICH WILL IMPACT THE AREA LATE
TUESDAY NIGHT AND INTO WEDNESDAY. AT THAT TIME...A SLIGHT RISK OF
SEVERE WEATHER IS IN THE FCST FOR OUR NW COUNTIES. BEST OMEGA
FORCING APPEARS TO BE AROUND 06Z WEDNESDAY ACROSS WESTERN TN.
BUT...THERE COULD BE A FEW STRONGER CELLS OVER THAT SAME AREA
EARLIER ON TUES AFTERNOON. STORM MOTION SHOULD RUN FROM SW TO NE.
SHOWERS AND TSTMS TO PERSIST INTO WEDNESDAY. ITS IMPORTANT TO NOTE
HOWEVER THAT OVERALL POPS WITH THIS SYSTEM ARE NOT DRASTICALLY HIGH.
IN FACT...MODELS NOT LEANING TOWARD DEEP MOISTURE WITH A WIDESPREAD
AREA OF RAIN OCCURRING. NEVERTHELESS...POPS IN THE 40-60 PERCENT
RANGE WILL BE INCLUDED FOR TUESDAY NT INTO WEDNESDAY. AFTER A FEW
LINGERING SHOWERS ON THURSDAY ACROSS THE PLATEAU...CLEARING WILL
OCCUR WITH DRIER AIR MOVING IN.
FOR THE NEAR TERM TEMPS...WILL AGAIN UNDERCUT THE HIGH TEMPS FOR
TUESDAY AND WEDNESDAY. OVERNIGHT LOWS FROM THE GUIDANCE APPEARS
REASONABLE.
IN THE EXT FCST...NICE LATE MAY CONDITIONS ARE ON TAP FOLLOWING THE
FROPA WHICH WAS MENTIONED IN THE SHORT TERM TIME FRAME.
THUS...SUNSHINE TO RETURN IN EARNEST FOR FRIDAY AND INTO THE
WEEKEND. THERMAL TROUGHING WILL BE SLOW TO GIVE WAY AND
THUS...MOSTLY SUNNY SKIES WITH BELOW NORMAL TEMPS AND LOWER
HUMIDITY LEVELS WILL PREVAIL THU THROUGH SAT. SUNDAY AND MONDAY...UPPER
RIDGING AND HEIGHT RISES WILL BE ON TAP. THIS WILL EQUATE TO HIGH
TEMPS BACK UP INTO THE 80S. BUT...STILL NOT SEEING ANY APPRECIABLE
PRECIP CHANCES THROUGH MONDAY.
21
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31
AREA FORECAST DISCUSSION
NWS SPOKANE WA
436 AM PDT Sun May 19 2013
.SYNOPSIS...
Another day of seasonably mild conditions are expected today with a
few mountain showers and possible thunderstorms. Monday will be a
dry and mild break period before a strong storm system enters the
region on Tuesday with a chance of showers and thunderstorms.
Showery and unseasonably cool conditions will envelop the region
from mid-week onward.
&&
.DISCUSSION...
Today and tonight...As longwave trof axis moves east ridging
moving in from the west will get within closer proximity to
Eastern Washington and Northern Idaho thus some decrease in
instability should result. Since the extreme western edge of the
trof is still close enough to influence the forecast area and
many short term model runs such as the HRRR depict some rotation
associated with the weak convection generated the idea is that
majority of the convection is of the elevated forced variety
rather than surface based type...especially when one considers
how much cloud cover is remaining in place which makes it much
much more difficult for surface based convection to initiate.
However since there is riding approaching from the west and getting
closer the drop in pops and precipitation amounts to near zero
after midnight remain a valid course of action. Forecast temps
given this trof remain just a sliver on the cool side of what
would be considered normal for this time of year. /Pelatti
Monday and Monday night...A relatively benign and quiet period
will prevail on Monday and Monday night as a weak upper level
ridge pops up over the region in advance of a deep upper level low
scheduled to arrive on or about Tuesday/Wednesday. thus...Monday
will probably be the last reasonably pleasant and dry day for the
region.
On Tuesday latest models are in good agreement and reasonably
consistent in digging a deep upper level low pressure out of the
Gulf of Alaska and placing it off the northwest coast by
afternoon. This will put the forecast area under a moist southerly
difluent flow on the east flank of this upper feature. This is a
showery and thundery pattern for the region...and while details
regarding actual frontal placement and deep instability are
uncertain at this time...confidence is growing that Tuesday will
be an increasingly active day of general deterioration from west
to east...with high temperatures over the east actually increasing
over Monday`s highs in a warm advective southerly flow
scenario...while over the west an onset of showers during the day
will moderate temperatures. The main thunder threat on Tuesday
will likely be over the east near the exiting thermal trough and
concentrated in the afternoon and evening hours.
From Tuesday night through Friday there is uncommonly good model
agreement...repeated over numerous run now and thus inspiring high
confidence...that the aforementioned deep closed low will take up
residence over or very near the forecast area. This will promote a
return to a cooler and showery pattern more like early April than
late May. Wednesday appears at this time to be the wettest
day...with the main tough baroclinic zone and surface cold front
efficiently enhancing available moisture into widespread showers
over most of the region. There is high confidecne that Thursday
and Friday will also be showery and cool...but the nature of the
showers will be more hit-and-miss with smaller areal extent than
Wednesday. Snow levels will likely drop down to the 4000 to 5000
foot range on average...4kft at night and 5kft during the day.
In summary...at this time there is high confidecne that Monday
will be dry and mild and Tuesday active and potentially
thundery. There is high confidence that Wednesday through Friday
will be cool and showery...with the best chance of very showery or
downright rainy conditions on Wednesday. /Fugazzi
Friday Night through Saturday Night: The unsettled weather pattern
looks to continue for the Inland NW. The low will remain almost
stationary given current model runs throughout the period which
will continue to pump Pacific moisture into the region. Given the
placement of the low and the increased cloud cover our daytime
high temperatures will not be able to reach potential maximums
keeping us a few degrees below normal and lows will follow the
same trend. Concerning the potential for rainfall in this pattern
I followed the same idea as the day shift with above climo POPs but
did increase a little for the NE Mtns of WA and the Mtns of the ID
Panhandle given the orientation of how the moisture will flow into
the region. Current models look to keep most of the heavier more
consistent rain north of the border in BC and lesser amounts in
the areas mentioned above. Given the location of the precip we
will have to continue to monitor the rivers and streams around the
region especially basins that receive contributions from the
areas of BC that will likely see more precip. Precip patterns and
amounts will continue to be refined as we push closer to this time
frame...but in general we can say the forecast will include below
normal temps with cloudy skies and an increased chance for precip.
/Fliehman
&&
.AVIATION...
12z TAFS: Weak low pressure gradualy moves east and allows for
an improvement as far as less clouds and drier conditions near
6Z Monday and beyond. Otherwise considerable mid level cloud cover
and some spotty shower activity remains but VFR conditions still
prevail. /Pelatti
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 66 46 72 52 76 42 / 20 10 0 0 20 50
Coeur d`Alene 65 44 71 47 77 42 / 30 20 0 0 20 60
Pullman 63 42 71 47 77 40 / 20 10 0 0 10 60
Lewiston 68 49 78 53 83 47 / 20 10 0 0 10 50
Colville 72 43 77 45 80 43 / 20 20 10 10 40 60
Sandpoint 65 42 72 44 77 41 / 50 30 10 0 30 70
Kellogg 60 46 70 50 76 41 / 40 30 10 0 20 60
Moses Lake 76 46 80 50 78 44 / 10 0 0 0 30 50
Wenatchee 73 49 78 53 72 44 / 0 0 0 0 40 50
Omak 74 43 78 46 76 44 / 10 10 0 0 50 50
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
217 AM PDT Sun May 19 2013
.SYNOPSIS...
Another day of seasonably mild conditions are expected today with a
few mountain showers and possible thunderstorms. Monday will be a
dry and mild break period before a strong storm system enters the
region on Tuesday with a chance of showers and thunderstorms.
Showery and unseasonably cool conditions will envelop the region
from mid-week onward.
&&
.DISCUSSION...
Today and tonight...As longwave trof axis moves east ridging
moving in from the west will get within closer proximity to
Eastern Washington and Northern Idaho thus some decrease in
instability should result. Since the extreme western edge of the
trof is still close enough to influence the forecast area and
many short term model runs such as the HRRR depict some rotation
associated with the weak convection generated the idea is that
majority of the convection is of the elevated forced variety
rather than surface based type...especially when one considers
how much cloud cover is remaining in place which makes it much
much more difficult for surface based convection to initiate.
However since there is riding approaching from the west and getting
closer the drop in pops and precipitation amounts to near zero
after midnight remain a valid course of action. Forecast temps
given this trof remain just a sliver on the cool side of what
would be considered normal for this time of year. /Pelatti
Monday and Monday night...A relatively benign and quiet period
will prevail on Monday and Monday night as a weak upper level
ridge pops up over the region in advance of a deep upper level low
scheduled to arrive on or about Tuesday/Wednesday. thus...Monday
will probably be the last reasonably pleasant and dry day for the
region.
On Tuesday latest models are in good agreement and reasonably
consistent in digging a deep upper level low pressure out of the
Gulf of Alaska and placing it off the northwest coast by
afternoon. This will put the forecast area under a moist southerly
difluent flow on the east flank of this upper feature. This is a
showery and thundery pattern for the region...and while details
regarding actual frontal placement and deep instability are
uncertain at this time...confidence is growing that Tuesday will
be an increasingly active day of general deterioration from west
to east...with high temperatures over the east actually increasing
over Monday`s highs in a warm advective southerly flow
scenario...while over the west an onset of showers during the day
will moderate temperatures. The main thunder threat on Tuesday
will likely be over the east near the exiting thermal trough and
concentrated in the afternoon and evening hours.
From Tuesday night through Friday there is uncommonly good model
agreement...repeated over numerous run now and thus inspiring high
confidence...that the aforementioned deep closed low will take up
residence over or very near the forecast area. This will promote a
return to a cooler and showery pattern more like early April than
late May. Wednesday appears at this time to be the wettest
day...with the main tough baroclinic zone and surface cold front
efficiently enhancing available moisture into widespread showers
over most of the region. There is high confidecne that Thursday
and Friday will also be showery and cool...but the nature of the
showers will be more hit-and-miss with smaller areal extent than
Wednesday. Snow levels will likely drop down to the 4000 to 5000
foot range on average...4kft at night and 5kft during the day.
In summary...at this time there is high confidecne that Monday
will be dry and mild and Tuesday active and potentially
thundery. There is high confidence that Wednesday through Friday
will be cool and showery...with the best chance of very showery or
downright rainy conditions on Wednesday. /Fugazzi
Friday Night through Saturday Night: The unsettled weather pattern
looks to continue for the Inland NW. The low will remain almost
stationary given current model runs throughout the period which
will continue to pump Pacific moisture into the region. Given the
placement of the low and the increased cloud cover our daytime
high temperatures will not be able to reach potential maximums
keeping us a few degrees below normal and lows will follow the
same trend. Concerning the potential for rainfall in this pattern
I followed the same idea as the day shift with above climo POPs but
did increase a little for the NE Mtns of WA and the Mtns of the ID
Panhandle given the orientation of how the moisture will flow into
the region. Current models look to keep most of the heavier more
consistent rain north of the border in BC and lesser amounts in
the areas mentioned above. Given the location of the precip we
will have to continue to monitor the rivers and streams around the
region especially basins that receive contributions from the
areas of BC that will likely see more precip. Precip patterns and
amounts will continue to be refined as we push closer to this time
frame...but in general we can say the forecast will include below
normal temps with cloudy skies and an increased chance for precip.
/Fliehman
&&
.AVIATION...
06z TAFS: Mostly cloud skies are expected over the region through
tonight with showers remaining confined mainly across the northern
mountains. Some stratus may begin to develop in the Spokane/Coeur
d`Alene areas tonight as the boundary layer remains moist, but
confidence is low as thick mid level cloud cover may not result in
enough cooling tonight lower in the atmosphere for stratus
development. Mountain showers are expected to develop through
Sunday afternoon, which may push south off the northern mountains
into KGEG, KSFF and KCOE with -RA possible. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 66 46 72 52 76 42 / 20 10 0 0 20 50
Coeur d`Alene 65 44 71 47 77 42 / 30 20 0 0 20 60
Pullman 63 42 71 47 77 40 / 20 10 0 0 10 60
Lewiston 68 49 78 53 83 47 / 20 10 0 0 10 50
Colville 72 43 77 45 80 43 / 20 20 10 10 40 60
Sandpoint 65 42 72 44 77 41 / 50 30 10 0 30 70
Kellogg 60 46 70 50 76 41 / 40 30 10 0 20 60
Moses Lake 76 46 80 50 78 44 / 10 0 0 0 30 50
Wenatchee 73 49 78 53 72 44 / 0 0 0 0 40 50
Omak 74 43 78 46 76 44 / 10 10 0 0 50 50
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1048 PM CDT MON MAY 20 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...
ISSUED AT 839 PM CDT MON MAY 20 2013
A LARGE CLUSTER OF TSTMS EXTENDING FROM MISSOURI INTO WSTRN IL WILL
LIKELY STAY MAINLY TO THE SOUTHEAST OF GRB CWA TONIGHT. HOWEVER...
SEVERAL SMALLER LINES OR CLUSTERS OF STORMS OVER SE MN AND IA ARE
EXPECTED TO CONSOLIDATE INTO A LARGE AREA AND LIFT NORTH THROUGH
THE FA DURING THE VERY LATE EVENING AND OVERNIGHT. THE HRRR AND
RAP MODELS SEEM TO HAVE A DECENT HANDLE ON THIS SITUATION...AND
SHOW THE CONVECTION OVERSPREADING C/EC WI BETWEEN 04Z-06Z...AND
NORTHERN WI BETWEEN 06Z-08Z. INSTABILITY IS NOT EXPECTED TO BE
GREAT...WITH MUCAPE IN THE 500-1000 J/KG RANGE...BUT DEEP LAYER
SHEAR SHOULD BE FAIRLY STRONG...IN THE 40-50 KT RANGE. DYNAMIC
FORCING FROM A S/W TROF AND 100 KT JET STREAK...PLUS MOISTURE
CONVERGENCE ON THE NOSE OF 35 KT LLJ WILL PROVIDE THE TRIGGER.
SUSPECT THAT ISOLATED SEVERE TSTMS WILL BE POSSIBLE IN C/EC WI
TOWARD THE BEGINNING OF THE EVENT...BEFORE THE STORMS FORM INTO A
LARGER CLUSTER. WET BULB ZERO HGTS AROUND 9K FT ARE SUPPORTIVE OF
LARGE HAIL...AND DCAPE VALUES OF 800-900 J/KG ARE MARGINALLY
SUPPORTIVE OF STG WIND GUSTS.
UPDATE
ISSUED AT 631 PM CDT MON MAY 20 2013
UPDATED POPS FOR THIS EVENING AND OVERNIGHT. SCT SHOWERS AND ISOLD
TSTMS WERE OCCURRING OVER NC WI DUE TO A S/W TROF AND LFQ OF AN
UPPER LEVEL JET. THIS ACTIVITY SHOULD LIFT NORTH OF THE REGION BY
01Z-02Z.
LATEST HRRR/RAP SUGGEST THAT A MORE SIGNIFICANT ROUND OF TSTMS
WILL ARRIVE IN OUR SOUTHERN COUNTIES LATE THIS EVG...AND QUICKLY
SPREAD NE THROUGH THE CWA DURING THE OVERNIGHT HOURS. THIS CONVECTION
WILL BE DRIVEN BY ANOTHER S/W TROF AND JET STREAK...AS WELL AS MOISTURE
CONVERGENCE ON THE NOSE OF A 30 KT LLJ. ALTHOUGH SFC BASED INSTABILITY
WILL BE WANING BY THAT TIME...SOME ELEVATED INSTABILITY WILL PERSIST
AND SHEAR PROFILES WILL BE SUPPORTIVE OF ORGANIZED STORMS. THE AREA
REMAINS IN A SLIGHT RISK FOR SEVERE TSTMS...SO WILL WATCH CLOSELY
TO SEE HOW THIS DEVELOPS AS THE EVG PROGRESSES.
&&
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 306 PM CDT MON MAY 20 2013
THE THREAT FOR SVR STORMS CONTS TO BE THE PRIMARY FOCUS OF THE
FCST FOR BOTH TNGT AND ON TUE.
THE 19Z MSAS SFC ANALYSIS SHOWED A STRONG AREA OF LOW PRES OVER
THE NE CORNER OF SD WITH A FRONTAL BOUNDARY EXTENDED EWD THRU
CNTRL WI. A CDFNT STRETCHED SWD FROM THE LOW THRU THE PLAINS. A
LOOK AT THE WATER VAPOR IMAGERY INDICATED AN MID-LEVEL AREA OF LOW
PRES OVER THE NRN PLAINS. TSTMS HAVE FIRED OVER IN LWR MI WHERE
BETTER INSTABILITY RESIDES AND SHWRS CONTINUED TO SPIN NWD OVER
WRN WI.
AN INITIAL SURGE OF DRIER AIR ALOFT WAS NOT HANDLED WELL BY THE
MDLS EARLIER TODAY...HOWEVER PREVAILING SW WINDS TO PUMP MORE
MOISTURE INTO WI LATER THIS AFTERNOON/EARLY EVENING AND HELP TO
LIFT CAPES INTO THE 1000-1500 J/KG RANGE. MODERATE TO STRONG 0-6KM
SHEAR REMAINS OVER THE REGION...THUS AS MOISTURE INCREASES AND A
TRIGGER ARRIVES (MID-LEVEL SPEED MAX)...EXPECT TO SEE CONVECTION
BLOSSOM TO OUR SOUTH AND OVERSPREAD NE WI LATER THIS EVENING. THE
TSTM ACTIVITY SHOULD BE LINE SEGMENTS WHICH COULD BRING SOME OF
THIS STRONGER WIND ALOFT DOWN TO THE SFC...THUS THE GREATEST SVR
THREAT WOULD BE DAMAGING WIND GUSTS. STORMS SHOULD WEAKEN A BIT
DURING THE OVRNGT HOURS AS INSTABILITY WEAKENS...BUT HAVE KEPT
SHWR/ISOLATED TSTM WORDING OVRNGT AS SHORTWAVE ENERGY TO STILL BE
MOVING THRU THE REGION.
THE UPR TROF TO OUR WEST IS FCST TO SLOWLY EDGE EAST ACROSS THE
PLAINS AND WEAKEN A BIT. MEANWHILE...THE SFC LOW TRACKS ACROSS THE
UPR MS VALLEY AND ALSO WEAKENS SOMEWHAT ON TUE. THE MAIN QUESTION
FOR TUE FOR NE WI IS HOW MANY CLOUDS WL STILL BE AROUND DURING THE
MORNING FROM OVRNGT CONVECTION? THE ATMOSPHERE SHOULD HAVE
STABILIZED BY THIS TIME AND WL HAVE TO WAIT FOR THE CLOUDS TO
BREAK UP TO PERMIT SUFFICIENT HEATING TO ALLOW DESTABILIZATION TO
TAKE PLACE. ANOTHER CONCERN WOULD BE THE ANTICIPATED MCS OVER THE
SRN PLAINS/MID-MS VALLEY WHICH COULD ROB SOME OF THE INCOMING GULF
MOISTURE. ONCE INSTABILITY OCCURS...MDLS SHOW ENUF SHEAR TO HELP
ORGANIZE THE NEXT ROUND OF STRONG TO SVR TSTMS FROM THE GREAT
LAKES SW TO THE OZARKS. SINCE THERE IS SOME DOUBT AS TO WHEN THE
NEW STORMS WOULD FIRE AND EXACTLY WHERE THEY WOULD FIRE...PREFER
TO FOCUS HIGHER POPS IN THE AFTERNOON.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 306 PM CDT MON MAY 20 2013
THE LATEST GFS ENSEMBLE MEAN INDICATES THAT THE PESKY UPPER LOW
THATS CURRENTLY OVER THE CENTRAL PLAINS WILL SHIFT EAST ACROSS THE
AREA WEDNESDAY NIGHT BEFORE DEPARTING. THEREAFTER...NW FLOW WILL
PREVAIL FOR SEVERAL DAYS...WHICH WILL LEAD TO QUIETER AND COOLER
CONDITIONS. THE NEXT CHANCE OF PRECIP FOLLOWING THE UPPER LOW WILL
OCCUR DUE TO RETURN FLOW NEXT WEEKEND...WHICH MODELS OFFER DIFFERENT
SOLUTIONS. AS IS USUAL...THE GFS IS MORE PROGRESSIVE IN ADVANCING
A WARM FRONT INTO THE REGION SATURDAY NIGHT INTO SUNDAY...WHICH THE
ECMWF PORTRAYS A STRONG HUDSON BAY HIGH KEEPING THE WARM FRONT TO
OUR SW. THE ECMWF HAS SUPPORT FROM THE CANADIAN SO THINK A
COMPROMISE BETWEEN THE TWO SOLUTIONS IS IN ORDER.
TUESDAY NIGHT THROUGH THURSDAY...UPPER LOW OVER THE DAKOTAS WILL
FINALLY SHIFT EAST TUESDAY NIGHT AND WEDNESDAY. BROAD SURFACE LOW
PRESSURE WILL MOVE EAST ACROSS WISCONSIN TUESDAY NIGHT BEFORE A
SECONDARY SURFACE LOW ORGANIZES OVER NORTHERN ILLINOIS. SHOULD HAVE
ENOUGH SURFACE INSTABILITY AND FORCING FOR THE THREAT OF STORMS TO
CONTINUE THROUGH TUESDAY EVENING. STORMS SHOULD DISSIPATE OVERNIGHT
ON TUESDAY...BUT SOME SHOWERS MAY CONTINUE OVER N-C WISCONSIN CLOSER
A STALLED OUT FRONT. SHOWERS LOOK TO BE A DECENT BET ON WEDNESDAY AS THE
SURFACE LOW MOVES FROM NORTHERN ILLINOIS INTO LOWER MICHIGAN AND THE
UPPER LOW MOVES OVERHEAD. OUT OF THE WARM SECTOR...TEMPS WILL BE
COOLING OFF INTO THE 60S WITH PLENTY OF CLOUDS AROUND. WILL LOWER HIGHS A
TAD. PRECIP WILL BE DIMINISHING FROM NW TO SE WEDNESDAY NIGHT AS
THE LOW HEADS TOWARDS THE EASTERN GREAT LAKES...AND A DRY HUDSON BAY
HIGH BUILDS OVER THE NORTHERN MISSISSIPPI VALLEY. THIS HIGH WILL
THEN RESIDE ACROSS THE AREA ON THURSDAY WITH HIGHS IN THE LOW TO MID
60S.
REST OF THE FORECAST...HUDSON BAY HIGH WILL CONTINUE TO BE PRESENT
ACROSS THE AREA ON FRIDAY WITH HIGHS NOT THAT DIFFERENT THAN ON
THURSDAY. BY FRIDAY NIGHT AND SATURDAY...A BUILDING RIDGE OVER THE
CENTRAL PART OF THE CONTINENT WILL PUSH A WARM FRONT NORTH ACROSS
THE GREAT PLAINS. SHOULD SEE A BAND OF PRECIP DEVELOP NORTH OF THE
BOUNDARY FROM THE NORTHERN PLAINS TO THE SOUTHWEST GREAT LAKES. THE
HUDSON BAY HIGH PRESSURE WILL CONTINUE TO FUNNEL IN VERY DRY AIR
ACROSS WISCONSIN DURING THIS TIME...AND TEND TO THINK THAT THE DRY
AIR WILL WIN OUT FOR MUCH OF THE FORECAST AREA. THINK PRECIP
CHANCES WILL IMPROVE OVER THE SECOND HALF OF THE WEEKEND AS THE
MID-LEVEL RIDGE MOVES EAST AND THE WARM FRONT LIFTS NORTH.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1043 PM CDT MON MAY 20 2013
SHRA/TSRA WILL BECOME MORE NUMEROUS AS THEY SPREAD NORTH INTO THE
FORECAST AREA OVERNIGHT. MVFR/LCL IFR CONDITIONS SHOULD ACCOMPANY
THE TSTMS...ALONG WITH A THREAT OF HEAVY RAINFALL...SMALL HAIL AND
BRIEF GUSTY WINDS. THE STORMS SHOULD TAPER OFF FROM SOUTH TO NORTH
LATE TONIGHT INTO TUESDAY MORNING...ALTHOUGH SHOWERS MAY LINGER
OVER FAR NORTHERN WI. SOME LINGERING LOW CLOUDS AND FOG MAY ALSO
PERSIST ACROSS THE FCST AREA THROUGH MID-MORNING. LOW PRESSURE
WILL MOVE INTO THE REGION ON TUESDAY AFTERNOON...AND SHOULD
GENERATE ANOTHER ROUND OF TSTMS. THE STORMS SHOULD TAPER OFF
FROM WEST TO EAST DURING THE LATE AFTERNOON AND EARLY EVENING.
PARTIAL CLEARING MAY CAUSE SOME FOG AND LOW CLOUDS TO DEVELOP
TUESDAY EVENING.
&&
.MARINE...
ISSUED AT 306 PM CDT MON MAY 20 2013
NEXT ROUND OF SHOWERS AND STORMS SHOULD OCCUR EARLY THIS
EVENING AND LINGER INTO THE EARLY MORNING HOURS. THESE STORMS COULD
PRODUCE STRONG WINDS. MOIST AIR FLOWING OVER THE COLDER WATERS OF
THE BAY AND LAKE WILL RESULT IN FOG AT TIMES THROUGH TUESDAY
NIGHT. THE FOG WILL BE LOCALLY DENSE WITH VISIBILITIES BELOW ONE
MILE AT TIMES.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........KIECKBUSCH
SHORT TERM.....AK
LONG TERM......MPC
AVIATION.......KIECKBUSCH
MARINE.........AK
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
903 PM CDT MON MAY 20 2013
NEW INFORMATION ADDED TO UPDATE SECTION
.UPDATE...
ISSUED AT 839 PM CDT MON MAY 20 2013
A LARGE CLUSTER OF TSTMS EXTENDING FROM MISSOURI INTO WSTRN IL WILL
LIKELY STAY MAINLY TO THE SOUTHEAST OF GRB CWA TONIGHT. HOWEVER...
SEVERAL SMALLER LINES OR CLUSTERS OF STORMS OVER SE MN AND IA ARE
EXPECTED TO CONSOLIDATE INTO A LARGE AREA AND LIFT NORTH THROUGH
THE FA DURING THE VERY LATE EVENING AND OVERNIGHT. THE HRRR AND
RAP MODELS SEEM TO HAVE A DECENT HANDLE ON THIS SITUATION...AND
SHOW THE CONVECTION OVERSPREADING C/EC WI BETWEEN 04Z-06Z...AND
NORTHERN WI BETWEEN 06Z-08Z. INSTABILITY IS NOT EXPECTED TO BE
GREAT...WITH MUCAPE IN THE 500-1000 J/KG RANGE...BUT DEEP LAYER
SHEAR SHOULD BE FAIRLY STRONG...IN THE 40-50 KT RANGE. DYNAMIC
FORCING FROM A S/W TROF AND 100 KT JET STREAK...PLUS MOISTURE
CONVERGENCE ON THE NOSE OF 35 KT LLJ WILL PROVIDE THE TRIGGER.
SUSPECT THAT ISOLATED SEVERE TSTMS WILL BE POSSIBLE IN C/EC WI
TOWARD THE BEGINNING OF THE EVENT...BEFORE THE STORMS FORM INTO A
LARGER CLUSTER. WET BULB ZERO HGTS AROUND 9K FT ARE SUPPORTIVE OF
LARGE HAIL...AND DCAPE VALUES OF 800-900 J/KG ARE MARGINALLY
SUPPORTIVE OF STG WIND GUSTS.
UPDATE
ISSUED AT 631 PM CDT MON MAY 20 2013
UPDATED POPS FOR THIS EVENING AND OVERNIGHT. SCT SHOWERS AND ISOLD
TSTMS WERE OCCURRING OVER NC WI DUE TO A S/W TROF AND LFQ OF AN
UPPER LEVEL JET. THIS ACTIVITY SHOULD LIFT NORTH OF THE REGION BY
01Z-02Z.
LATEST HRRR/RAP SUGGEST THAT A MORE SIGNIFICANT ROUND OF TSTMS
WILL ARRIVE IN OUR SOUTHERN COUNTIES LATE THIS EVG...AND QUICKLY
SPREAD NE THROUGH THE CWA DURING THE OVERNIGHT HOURS. THIS CONVECTION
WILL BE DRIVEN BY ANOTHER S/W TROF AND JET STREAK...AS WELL AS MOISTURE
CONVERGENCE ON THE NOSE OF A 30 KT LLJ. ALTHOUGH SFC BASED INSTABILITY
WILL BE WANING BY THAT TIME...SOME ELEVATED INSTABILITY WILL PERSIST
AND SHEAR PROFILES WILL BE SUPPORTIVE OF ORGANIZED STORMS. THE AREA
REMAINS IN A SLIGHT RISK FOR SEVERE TSTMS...SO WILL WATCH CLOSELY
TO SEE HOW THIS DEVELOPS AS THE EVG PROGRESSES.
&&
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 306 PM CDT MON MAY 20 2013
THE THREAT FOR SVR STORMS CONTS TO BE THE PRIMARY FOCUS OF THE
FCST FOR BOTH TNGT AND ON TUE.
THE 19Z MSAS SFC ANALYSIS SHOWED A STRONG AREA OF LOW PRES OVER
THE NE CORNER OF SD WITH A FRONTAL BOUNDARY EXTENDED EWD THRU
CNTRL WI. A CDFNT STRETCHED SWD FROM THE LOW THRU THE PLAINS. A
LOOK AT THE WATER VAPOR IMAGERY INDICATED AN MID-LEVEL AREA OF LOW
PRES OVER THE NRN PLAINS. TSTMS HAVE FIRED OVER IN LWR MI WHERE
BETTER INSTABILITY RESIDES AND SHWRS CONTINUED TO SPIN NWD OVER
WRN WI.
AN INITIAL SURGE OF DRIER AIR ALOFT WAS NOT HANDLED WELL BY THE
MDLS EARLIER TODAY...HOWEVER PREVAILING SW WINDS TO PUMP MORE
MOISTURE INTO WI LATER THIS AFTERNOON/EARLY EVENING AND HELP TO
LIFT CAPES INTO THE 1000-1500 J/KG RANGE. MODERATE TO STRONG 0-6KM
SHEAR REMAINS OVER THE REGION...THUS AS MOISTURE INCREASES AND A
TRIGGER ARRIVES (MID-LEVEL SPEED MAX)...EXPECT TO SEE CONVECTION
BLOSSOM TO OUR SOUTH AND OVERSPREAD NE WI LATER THIS EVENING. THE
TSTM ACTIVITY SHOULD BE LINE SEGMENTS WHICH COULD BRING SOME OF
THIS STRONGER WIND ALOFT DOWN TO THE SFC...THUS THE GREATEST SVR
THREAT WOULD BE DAMAGING WIND GUSTS. STORMS SHOULD WEAKEN A BIT
DURING THE OVRNGT HOURS AS INSTABILITY WEAKENS...BUT HAVE KEPT
SHWR/ISOLATED TSTM WORDING OVRNGT AS SHORTWAVE ENERGY TO STILL BE
MOVING THRU THE REGION.
THE UPR TROF TO OUR WEST IS FCST TO SLOWLY EDGE EAST ACROSS THE
PLAINS AND WEAKEN A BIT. MEANWHILE...THE SFC LOW TRACKS ACROSS THE
UPR MS VALLEY AND ALSO WEAKENS SOMEWHAT ON TUE. THE MAIN QUESTION
FOR TUE FOR NE WI IS HOW MANY CLOUDS WL STILL BE AROUND DURING THE
MORNING FROM OVRNGT CONVECTION? THE ATMOSPHERE SHOULD HAVE
STABILIZED BY THIS TIME AND WL HAVE TO WAIT FOR THE CLOUDS TO
BREAK UP TO PERMIT SUFFICIENT HEATING TO ALLOW DESTABILIZATION TO
TAKE PLACE. ANOTHER CONCERN WOULD BE THE ANTICIPATED MCS OVER THE
SRN PLAINS/MID-MS VALLEY WHICH COULD ROB SOME OF THE INCOMING GULF
MOISTURE. ONCE INSTABILITY OCCURS...MDLS SHOW ENUF SHEAR TO HELP
ORGANIZE THE NEXT ROUND OF STRONG TO SVR TSTMS FROM THE GREAT
LAKES SW TO THE OZARKS. SINCE THERE IS SOME DOUBT AS TO WHEN THE
NEW STORMS WOULD FIRE AND EXACTLY WHERE THEY WOULD FIRE...PREFER
TO FOCUS HIGHER POPS IN THE AFTERNOON.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 306 PM CDT MON MAY 20 2013
THE LATEST GFS ENSEMBLE MEAN INDICATES THAT THE PESKY UPPER LOW
THATS CURRENTLY OVER THE CENTRAL PLAINS WILL SHIFT EAST ACROSS THE
AREA WEDNESDAY NIGHT BEFORE DEPARTING. THEREAFTER...NW FLOW WILL
PREVAIL FOR SEVERAL DAYS...WHICH WILL LEAD TO QUIETER AND COOLER
CONDITIONS. THE NEXT CHANCE OF PRECIP FOLLOWING THE UPPER LOW WILL
OCCUR DUE TO RETURN FLOW NEXT WEEKEND...WHICH MODELS OFFER DIFFERENT
SOLUTIONS. AS IS USUAL...THE GFS IS MORE PROGRESSIVE IN ADVANCING
A WARM FRONT INTO THE REGION SATURDAY NIGHT INTO SUNDAY...WHICH THE
ECMWF PORTRAYS A STRONG HUDSON BAY HIGH KEEPING THE WARM FRONT TO
OUR SW. THE ECMWF HAS SUPPORT FROM THE CANADIAN SO THINK A
COMPROMISE BETWEEN THE TWO SOLUTIONS IS IN ORDER.
TUESDAY NIGHT THROUGH THURSDAY...UPPER LOW OVER THE DAKOTAS WILL
FINALLY SHIFT EAST TUESDAY NIGHT AND WEDNESDAY. BROAD SURFACE LOW
PRESSURE WILL MOVE EAST ACROSS WISCONSIN TUESDAY NIGHT BEFORE A
SECONDARY SURFACE LOW ORGANIZES OVER NORTHERN ILLINOIS. SHOULD HAVE
ENOUGH SURFACE INSTABILITY AND FORCING FOR THE THREAT OF STORMS TO
CONTINUE THROUGH TUESDAY EVENING. STORMS SHOULD DISSIPATE OVERNIGHT
ON TUESDAY...BUT SOME SHOWERS MAY CONTINUE OVER N-C WISCONSIN CLOSER
A STALLED OUT FRONT. SHOWERS LOOK TO BE A DECENT BET ON WEDNESDAY AS THE
SURFACE LOW MOVES FROM NORTHERN ILLINOIS INTO LOWER MICHIGAN AND THE
UPPER LOW MOVES OVERHEAD. OUT OF THE WARM SECTOR...TEMPS WILL BE
COOLING OFF INTO THE 60S WITH PLENTY OF CLOUDS AROUND. WILL LOWER HIGHS A
TAD. PRECIP WILL BE DIMINISHING FROM NW TO SE WEDNESDAY NIGHT AS
THE LOW HEADS TOWARDS THE EASTERN GREAT LAKES...AND A DRY HUDSON BAY
HIGH BUILDS OVER THE NORTHERN MISSISSIPPI VALLEY. THIS HIGH WILL
THEN RESIDE ACROSS THE AREA ON THURSDAY WITH HIGHS IN THE LOW TO MID
60S.
REST OF THE FORECAST...HUDSON BAY HIGH WILL CONTINUE TO BE PRESENT
ACROSS THE AREA ON FRIDAY WITH HIGHS NOT THAT DIFFERENT THAN ON
THURSDAY. BY FRIDAY NIGHT AND SATURDAY...A BUILDING RIDGE OVER THE
CENTRAL PART OF THE CONTINENT WILL PUSH A WARM FRONT NORTH ACROSS
THE GREAT PLAINS. SHOULD SEE A BAND OF PRECIP DEVELOP NORTH OF THE
BOUNDARY FROM THE NORTHERN PLAINS TO THE SOUTHWEST GREAT LAKES. THE
HUDSON BAY HIGH PRESSURE WILL CONTINUE TO FUNNEL IN VERY DRY AIR
ACROSS WISCONSIN DURING THIS TIME...AND TEND TO THINK THAT THE DRY
AIR WILL WIN OUT FOR MUCH OF THE FORECAST AREA. THINK PRECIP
CHANCES WILL IMPROVE OVER THE SECOND HALF OF THE WEEKEND AS THE
MID-LEVEL RIDGE MOVES EAST AND THE WARM FRONT LIFTS NORTH.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1243 PM CDT MON MAY 20 2013
SCT SHRA/ISOLD TSRA OVER NC WI SHOULD LIFT NORTH INTO THE UPPER
PENINSULA BY 01Z-02Z. ADDITIONAL SHRA/TSRA SHOULD MOVE INTO C/EC WI
LATE THIS EVG...AND SPREAD NORTH DURING THE OVERNIGHT HOURS. THE STORMS
SHOULD TAPER OFF OVER NORTHERN WI BY TUESDAY MORNING...BUT SOME LINGERING
LOW CLOUDS AND FOG MAY PERSIST ACROSS THE FCST AREA THROUGH MID-MORNING.
LOW PRESSURE WILL MOVE INTO THE REGION ON TUESDAY AFTERNOON...AND SHOULD
GENERATE ANOTHER ROUND OF TSTMS. MVFR CONDITIONS SHOULD ACCOMPANY ANY
TSTMS.
&&
.MARINE...
ISSUED AT 306 PM CDT MON MAY 20 2013
NEXT ROUND OF SHOWERS AND STORMS SHOULD OCCUR EARLY THIS
EVENING AND LINGER INTO THE EARLY MORNING HOURS. THESE STORMS COULD
PRODUCE STRONG WINDS. MOIST AIR FLOWING OVER THE COLDER WATERS OF
THE BAY AND LAKE WILL RESULT IN FOG AT TIMES THROUGH TUESDAY
NIGHT. THE FOG WILL BE LOCALLY DENSE WITH VISIBILITIES BELOW ONE
MILE AT TIMES.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........KIECKBUSCH
SHORT TERM.....AK
LONG TERM......MPC
AVIATION.......KIECKBUSCH
MARINE.........AK
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
849 PM CDT MON MAY 20 2013
.UPDATE...
LATEST RUC SHOWS A 105 KNOT 250 MB JET MAX OVER EASTERN IOWA PUSHING
NORTH AND INCREASING TO 110 KNOTS AS IT REACHES CENTRAL WISCONSIN
BY MIDNIGHT. THIS INCREASES THE UPPER DIVERGENCE. THE 50 KNOT 850
MB WIND MAX ALSO LIFTS NORTHEAST MAINLY TOWARD CHICAGO. THIS
INCREASES THE LOW LEVEL MOISTURE CONVERGENCE ACROSS MUCH OF
SOUTHEAST AND SOUTH CENTRAL WISCONSIN. AS A RESULT EXPECT
THUNDERSTORM CHANCES TO INCREASE CONSIDERABLY. THE LIMITING FACTOR
IS THE INSTABILITY. ZERO TO 1 KM CAP IS MODEST AT BEST...BUT WITH
THE INCREASING LOW LEVEL JET...INSTABILITY MAY BE MORE THAN MODELS
INDICATE...SINCE THE RAP IS SATURATING THE SOUNDINGS TO MOIST ADIABATIC.
GIVEN THE INITIAL MID/LOW LEVEL DRIER AIR DOWNDRAFT CAPE IS NEAR
1000 J/KG. THEREFORE DAMAGING WIND POTENTIAL WILL EXIST INTO THE
EARLY MORNING HOURS.
&&
.AVIATION/06Z TAFS/...
EXPECT A BAND OF THUNDERSTORMS TO AFFECT SOUTH CENTRAL AND
SOUTHEAST WISCONSIN OVERNIGHT. SOME IFR IN CIGS/VSBYS...ALONG WITH
STRONG WIND POTENTIAL. SOME BRIEF MVFR AROUND SUNRISE...THEN
MAINLY VFR TUESDAY WITH A CHANCE OF AFTERNOON THUNDERSTORMS.
&&
.PREV DISCUSSION... /ISSUED 331 PM CDT MON MAY 20 2013/
VERY SHORT TERM...TONIGHT AND TUESDAY. FORECAST CONFIDENCE...LOW
TO MEDIUM.
BIGGEST CONCERN INTO TONIGHT IS TIMING AND STRENGTH OF EXPECTED
THUNDERSTORMS. SPC IS MAINTAINING A SLIGHT RISK FOR SEVERE STORMS
ACROSS THE FORECAST AREA. LATEST NAM AND RAP SOUNDINGS AGREE THAT
THE ENVIRONMENT STILL LOOKS FAVORABLE FOR STRONG TO SEVERE STORMS.
WITH THE CONTINUED SUNSHINE...SHOULD SEE SFC BASED CAPE VALUES GET
IN THE 1000-1500 J/KG RANGE BY LATE AFTERNOON OR EARLY EVENING.
ADDITIONALLY...PLENTY OF 0-6 KM BULK SHEAR...GENERALLY 35-45 KT.
PLENTY OF MOISTURE AS WELL...WITH PRECIPITABLE WATER VALUES
INCREASING TO AROUND 1.25 INCHES THIS EVENING...ABOVE CLIMATOLOGICAL
NORMALS.
WITH A DECENT ENVIRONMENTAL SETUP...WILL JUST BE WAITING FOR THE
TRIGGER. TIMING OF UPSTREAM SHORTWAVE ALONG WITH LATEST HRRR AND
LOCAL WRF4L MODEL INDICATE THAT CONVECTION MAY HOLD OFF ACROSS
SOUTHERN WISCONSIN UNTIL THE MID-EVENING HOURS. ONE THING TO NOTE IS
THAT THE LAST FEW RUNS OF MESOSCALE MODELS HAVE BEEN ALL OVER THE
PLACE WITH CONVECTIVE SOLUTIONS FOR THIS EVENING...SO NOT A TON OF
CERTAINTY AT THIS POINT.
LOW PRESSURE REMAINING TO THE WEST WILL KEEP SOUTHERN WISCONSIN IN A
WARM AN UNSTABLE ENVIRONMENT THROUGH TUESDAY...THUS CHANCE FOR
THUNDERSTORMS WILL CONTINUE. SIMILAR TO TODAY...NOT A LOT OF
CERTAINTY IN TIMING AND PLACEMENT OF DEVELOPMENT. ANY STORMS THAT DO
DEVELOP TOMORROW WILL HAVE THE CHANCE TO BECOME STRONG TO
SEVERE...WITH SPC MAINTAINING A SLIGHT RISK FOR SEVERE STORMS.
SHORT TERM...TUESDAY NIGHT THROUGH THURSDAY. FORECAST CONFIDENCE
MEDIUM.
CLOSED LOW FINALLY BEGINS TO MOVE AS IT OPENS AND BECOMES PHASED
WITH TROUGH DROPPING TOWARD THE NORTHERN GREAT LAKES AS IT ROTATES
AROUND POLAR VORTEX JUST EAST OF HUDSON BAY.
ONE MORE ROUND OF CONVECTION EXPECTED WITH 500 MB SHORT WAVE TUE
NGT/WED AM WITH LAYER Q-VECTOR MAXIMA AND FRONTOGENETIC FORCING
INDICATING BEST CHANCES MAINLY AFTER 06Z WED...WITH MAX
FRONTOGENETIC FORCING OVER THE CWA AT 12Z WED. FORCING LIFTS
THRU...STALLS AND THEN DROPS BACK ACROSS REGION AS SYSTEM OPENS AND
MOVES RIGHT ACROSS THE STATE...WITH MID-LEVEL TROF AXIS SOUTH OF CWA
AROUND 18Z THURSDAY. THE SLIGHTLY DIFFERING SOLUTIONS TO TIMING AND
STRUCTURE AMONG THE MODELS LEADS TO VARIOUS AMOUNTS OF QPF. WENT
WITH BLENDED QPF AMOUNTS WITH A LEAN TOWARD THE HIGHER NUMBERS...BUT
IF CONVERGENCE BAND SETS UP RIGHT OVER THE REGION...THEN AMOUNTS
COULD GO EVEN HIGHER AND AREAL/RIVER FLOODING COULD COME INTO PLAY.
NOT ENOUGH CONFIDENCE TO RE-ISSUE AN EFS AT THIS TIME BUT WILL NEED
TO BE WATCHED.
TEMPERATURES DO NOT FALL MUCH TUESDAY NIGHT WITH CLOUDS AND THE AREA
STAYING ROUGHLY TO THE WARM SIDE OF THE LOW AS IT MOVES THROUGH SO
FOLLOWED LOWS CLOSER TO THE WARMER GUIDANCE NUMBERS. HIGHS WEDNESDAY
WILL BE AROUND MID DAY...THEN COOL WITH WINDS TURNING NORTHERLY AS
SURFACE LOW/TROUGH SLIDES BY...THOUGH LINGERING TROUGHINESS WILL
PREVENT MUCH OF A GRADIENT UNTIL CLOSER TO THURSDAY MORNING. HIGHS
THURSDAY WILL ONLY GET TO THE MID 60S WELL INLAND...WITH 50S ALONG
THE LAKE.
LONG TERM...THURSDAY NIGHT THROUGH MONDAY. FORECAST CONFIDENCE
AMOUNT OF COOLING VARIES WITH DEPTH OF EVOLVING 500 MB TROUGH OVER
EASTERN CANADA. OMEGA BLOCK SETS UP WITH AN AMPLIFYING RIDGE OVER
THE PLAINS BETWEEN EASTERN CANADA VORTEX AND CLOSED LOW OVER THE
PACIFIC NW...WITH THE FORECAST AREA REMAINING UNDER THE NW FLOW OF
THE EASTERN TROUGH THROUGH SATURDAY. LESS AMPLIFIED ECMWF ALLOWS
WARM AIR ADVECTION PRECIPITATION AHEAD OF SHORT WAVE UNDERCUTTING
THE RIDGE AND ASSOCIATED INVERTED SURFACE TROUGH CROSSING THE REGION
FRIDAY NIGHT AND SATURDAY. MORE DOMINANT SURFACE HIGH PRESSURE WITH
MORE AMPLIFIED GFS/GEM HOLDS PCPN CHANCES OFF UNTIL SATURDAY
AFTERNOON/SATURDAY NIGHT ON THE GEM...AND NOT UNTIL SUNDAY WITH THE
GFS. WHILE THE CONSENSUS BLEND HAS PRECIPITATION CHANCES THROUGH THE
HOLIDAY WEEKEND DUE TO THE TIMING SPREAD IN THE MODELS...THERE WILL
BE DRY PERIODS. TEMPERATURES WILL BE BELOW NORMAL...WITH HIGHS
TRYING TO GET BACK INTO THE LOWER 70S MONDAY AWAY FROM THE LAKE.
AVIATION/00Z TAFS/...
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH TUESDAY...THOUGH
LOWER CIGS/VSBYS POSSIBLE IN ANY THUNDERSTORMS. BIG ISSUE THROUGH
TOMORROW REMAINS TIMING ROUNDS OF THUNDERSTORMS. LOOKS QUIET THROUGH
LATE AFTERNOON...WITH LATEST MESOSCALE MODELS SUGGESTING DEVELOPMENT
POSSIBLE THIS EVENING AND INTO THE NIGHT. TOOK A STAB AT BEST CHANCE
FOR STORMS IN THE TAFS...THOUGH STILL HAD TO KEEP IT FAIRLY GENERAL
DUE TO A GOOD AMOUNT OF UNCERTAINTY. CHANCE FOR STORMS WILL CONTINUE
TUESDAY.
MARINE...
WILL LIKELY SEE GUSTS TO 25 KNOTS FROM NORTH POINT LIGHT SOUTHWARD
INTO EARLY EVENING...UNTIL DAYTIME HEATING/MIXING DECREASES. WILL
THUS KEEP THE SMALL CRAFT ADVISORY GOING UNTIL 01Z. FARTHER
NORTH...COULD SEE A FEW GUSTS TO 25 KNOTS...BUT OVERALL GRADIENT IS
A BIT WEAKER. PLUS...WINDS CONTINUE TO HAVE AN ONSHORE COMPONENT AT
TIMES ACROSS THE NORTH...WHICH SHOULD LIMIT GUST POTENTIAL DUE TO
THE STABLE AIRMASS OVER THE LAKE.
WINDS WILL MAINLY BE SOUTH TO SOUTHWEST THROUGH TUESDAY...SO OVERALL
FOG POTENTIAL WILL BE LIMITED. COULD SEE SOME FOG FOR A TIME IF
WINDS ARE SOUTHEAST LONGER THAN EXPECTED.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...HENTZ
TONIGHT/TUESDAY AND AVIATION/MARINE...DDV
TUESDAY NIGHT THROUGH MONDAY...REM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
608 PM CDT MON MAY 20 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 325 PM CDT MON MAY 20 2013
SURFACE MAP THIS AFTERNOON HAS A DEEP 995MB LOW OVER NORTHEAST SD
WITH A COLD FRONT/OCCLUSION EXTENDING SOUTHEAST OUT OF THE LOW INTO CENTRAL
MN/WI. DEW POINT ANALYSIS SHOWS DRIER AIR HAS PUSHED INTO THE AREA
TODAY BEHIND THE COLD FRONT. VIS SATELLITE SHOWING GROWING CUMULUS
FIELD GROWING ACROSS THE AREA...WITH LAPS INDICATING 0-1KM MLCAPE
ONLY AROUND 500J/KG AT THIS TIME. MEANWHILE...WATER VAPOR
IMAGERY/RAP H3 ANALYSIS SHOWING A JET MAX LIFTING NORTHEAST OUT OF
KS TOWARD THE AREA. THIS FEATURE IS EXPECTED TO INTERACT WITH A
DRYLINE MOVING NORTHEAST OUT OF NEB THIS EVENING FOR ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS. RAP13 SHOWS 0-1KM CAPE INCREASING INTO
THE 1300J/KG BY 03Z ALONG WITH AMPLE 0-3KM BULK SHEAR IN THE 35-40KT
RANGE. APPEAR STAGE IS SET FOR ANOTHER SEVERE THREAT WITH DAMAGING
WIND AND LARGE HAIL BEING THE MAIN THREAT. TORNADO THREAT APPEARS
SLIGHTLY DIMINISHED AT THIS POINT DUE TO HIGHER LIFTED CONDENSATION
LEVELS/LCLS. LOOKING FOR THE CONVECTION TO WANE AFTER MIDNIGHT AS
THE BOUNDARY AND MOISTURE TRANSPORT MOVES NORTHEAST OUT OF THE AREA.
FOR TUESDAY...EXPECTING SLIGHTLY DRIER AIR TO OVERSPREAD MUCH OF THE
AREA IN DRY SLOT OF THE LOW AS IT MOVES THROUGH SOUTHERN MN. FAIRLY
STEEP LAPSE RATES WILL BE IN PLACE...HOWEVER WITH NO DEFINITE
BOUNDARY TO FOCUS CONVECTION...WENT WITH LOWER-END CONVECTION
PROBABILITIES SOUTHWEST OF I-94 WITH HIGHER POPS NORTHEAST OF THIS.
OTHERWISE...PLAN ON COOLER BUT NEAR NORMAL HIGH TEMPERATURES IN THE
70S.
.LONG TERM...(TUESDAY NIGHT THROUGH MEMORIAL DAY)
ISSUED AT 325 PM CDT MON MAY 20 2013
A BREAK IN THE ACTION IS EXPECTED TUESDAY NIGHT AS THE DRY SLOT OF
THE LOW CONTINUES TO WORK NORTHEAST THROUGH THE AREA AND DEFORMATION
SHRA/TS ACTIVITY REMAINS NORTHWEST. FOR WEDNESDAY...LOOK FOR THE LOW
TO SLIP EAST TOWARD SOUTHERN LAKE MICHIGAN WITH THE DEFORMATION
SHRA/ISOLATED THUNDER WORKING SOUTHEAST ACROSS THE AREA. WITH THE
DYNAMIC COOLING OF THE UPPER LOW/CLOUDS/PRECIPITATION...PLAN ON
HIGHS ONLY IN THE 60S. SHOWER CHANCES STAY IN THE FORECAST THROUGH
WEDNESDAY NIGHT/THURSDAY MORNING AS THE LOW SLOWLY MOVES EAST INTO
THE GREAT LAKES REGION.
FOR THURSDAY NIGHT/FRIDAY...APPEARS MUCH DRIER AIR WILL ADVECT INTO
THE AREA ON NORTH/NORTHEAST WINDS FROM HIGH PRESSURE OVER ONTARIO
CANADA. HIGHS COOL TREND CONTINUES THURSDAY/FRIDAY WITH READINGS
TOPPING OFF IN THE 60S.
SHOWER AND THUNDERSTORMS EXPECTED TO RE-ENTER THE PICTURE FRIDAY
NIGHT AND THEN LAST INTO SATURDAY AS A MID-LEVEL TROUGH OF LOW
PRESSURE MOVES THROUGH THE NORTHERN PLAINS INTO IA. APPEARS HIGHEST
PROBABILITY RAIN CHANCES REMAIN SOUTHWEST OF I-94 WITH DRIER
SOUTHEAST OUTFLOW OUT OF HIGH PRESSURE DROPPING INTO THE GREAT LAKES
REGION. RAIN CHANCES GET A LITTLE IFFY THROUGH THE REMAINDER OF THE
WEEKEND WITH THAT WEAK MID-LEVEL WAVE SKIMMING SOUTH OF THE AREA AND
HIGH PRESSURE REMAINING OVER ONTARIO/GREAT LAKES REGION. ONE THING
LOOKS SURE THOUGH...AND THAT COOLER THAN NORMAL TEMPERATURES WITH
HIGHS SATURDAY AND SUNDAY REMAINING IN THE 60S...WARMING SLIGHTLY
INTO THE MID 60S/LOWER 70S FOR MEMORIAL DAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 607 PM CDT MON MAY 20 2013
ADDITIONAL CONVECTIVE ACTIVITY HAS BEEN SLOW TO DEVELOP TODAY.
SOME ACTIVITY STARTING TO DEVELOP OVER WESTERN IOWA AHEAD OF THE
NEXT SHORT WAVE TROUGH ROUNDING THE BASE OF THE UPPER LEVEL
TROUGH. THE 22.21Z HRRR SHOWS THIS AREA OF CONVECTION WILL
CONTINUE TO ENHANCE THROUGH THE EVENING MOVING NORTHEAST TOWARD
THE REGION AND POSSIBLY IMPACTING THE TAF SITES AROUND 03Z FOR A 3
TO 4 HOUR PERIOD. HAVE ADJUSTED THE TIMING OF THE VCTS IN BOTH
TAFS TO REFLECT THIS NEW TIMING. ONCE THIS WAVE MOVES PAST THE
AREA...NOT A LOT OF ACTIVITY IS EXPECTED FOR THE REMAINDER OF THE
PERIOD. THE FRONT OVER EASTERN NEBRASKA IS EXPECTED TO SWING
THROUGH THE AREA EARLY TUESDAY AFTERNOON BRINGING THE WINDS AROUND
TO A MORE SOUTHWEST TO WEST DIRECTION. THIS WILL REALLY LIMIT THE
LOW LEVEL CONVERGENCE AND JUST EXPECTING A VFR CEILING TO BE IN
PLACE AS THE UPPER LEVEL LOW DRIFTS CLOSER TO THE AREA.
&&
.HYDROLOGY...
ISSUED AT 325 PM CDT MON MAY 20 2013
WITH BETTER FOCUS FOR CONVECTION THIS EVENING BEING ALONG AND EAST
OF THE MISSISSIPPI RIVER....HAVE DECIDED TO DROP THE FLOOD WATCH
THAT WAS IN EFFECT FOR PORTIONS OF SOUTHEAST MN/A PART OF NORTHEAST
IA. HOWEVER...WILL HAVE TO REMAIN ON HIGH ALERT FOR RIVER
FLOODING...PARTICULARLY ALONG THE ROOT RIVER IN SOUTHEAST MN AND THE
CEDAR IN NORTHEAST WHERE RIVER FLOOD WARNINGS ARE IN EFFECT. OTHER
RIVERS AND TRIBUTARIES WILL ALSO HAVE TO WATCHED ACROSS SOUTHEAST
MN/NORTHEAST IA FOR RISING WITHIN BANK LEVELS FROM RECENT HEAVY
RAINFALL ACTIVITY. DRYING EXPECTED FINALLY ON THURSDAY AS HIGH
PRESSURE NOSES IN FROM CANADA.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...04
HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
348 PM CDT SUN MAY 19 2013
.VERY SHORT TERM...TONIGHT AND MONDAY...FORECAST CONFIDENCE MEDIUM.
WATER VAPOR IMAGERY IS SHOWING A SERIES OF SHORT WAVES/VORT
MAXES/PERTURBATIONS LINING UP FROM THE PACIFIC NW TO NORTHERN NEW
MEXICO/PANHANDLE REGION OF TX/OK THAT WILL BE DIVING INTO AND AROUND
THE BASE OF A DEEPENING TROUGH OVER THE DAKOTAS. THESE WILL PROVIDE
THE TRIGGERING MECHANISM FOR SUCCESSIVE ROUNDS OF SHOWERS AND STORMS
OVER THE NEXT 24 TO 36 HOURS.
A CLUSTER OF THUNDERSTORMS OVER SOUTH CENTRAL WI PRODUCING WINDS OF
50 TO 60 MPH IS WEAKENING AS IT MOVES FURTHER EAST INTO THE MORE
CAPPED ENVIRONMENT. A COUPLE OF SITES HAVE REPORTED GUSTS OF 35 TO
45 MPH IN THE WAKE OF THIS SMALL TSTORM COMPLEX.
NOW KEEPING AN EYE ON CONVECTION IN CENTRAL IOWA THAT IS ASSOCIATED
WITH ANOTHER SHORTWAVE TROUGH EXTENDING SE FROM THE MCV NOW OVER SW
MN. HRRR AND WRF-ARW MODELS BRING THIS AREA OF CONVECTION INTO SOUTH
CENTRAL WI AROUND 23Z. SLIGHT STRENGTHENING OF THE LLJ OVER IL
DURING THIS TIME ALONG WITH 850MB WARM AIR ADVECTION AND THIS
SHORTWAVE TROUGH...ALONG WITH MIXED LAYER CAPE 1000-1300 J/KG AND
SHEAR PARAMETERS /0-3KM SHEAR AROUND 20 KNOTS WILL BE FAVORABLE TO
SUPPORT ONGOING SURFACE-BASED CONVECTION LATE THIS AFTERNOON...AND
MORE ELEVATED CONVECTION AS IT MOVES TOWARD SOUTHEAST WI. THE SEVERE
POTENTIAL IS THERE FOR HAIL AND STRONG WINDS.
THERE IS ANOTHER SHORTWAVE ON THE HEELS OF THIS ONE...CURRENTLY OVER
SOUTHWEST IOWA. MESOSCALE MODELS SHOW THIS ONE TO BE THE SOURCE OF
AN OVERNIGHT CONVECTIVE COMPLEX...LIKELY HITTING SOUTHERN WI BETWEEN
06Z TO 12Z MONDAY...BUT EXACT TIMING IS DEBATABLE. CORFIDI VECTORS
WEAKEN OVER SOUTHERN WI DURING THIS TIME...SUGGESTING SLOW-MOVING
THUNDERSTORMS AND THE HEAVY RAIN/LOCALIZED FLOODING POTENTIAL.
SEVERE HAIL AND WINDS WILL ALSO BE POSSIBLE WITH THIS ROUND.
THEN IT WILL BE A MATTER OF HOW QUICKLY THE CONVECTIVE DEBRIS CAN
CLEAR IN ORDER FOR THE ATMOSPHERE TO RE-DESTABILIZE IN SOUTHERN WI.
IT WILL ALSO DEPEND ON WHERE THE EFFECTIVE WARM FRONT SETS
UP...WHICH WILL BE BASED ON OVERNIGHT CONVECTION. MODELS ARE
SUGGESTING THE WARM FRONT WILL BE UP IN NORTHERN WI BY MONDAY
AFTERNOON...BUT SOMETIMES MODELS TEND TO MOVE IT TOO FAR TO THE
NORTH. WILL NEED TO MONITOR THIS TREND.
THE CRAVEN-WIEDENFELD AGGREGATE SEVERE PARAMETER /CWASP/ IS
BASICALLY A SCORING/RATING SYSTEM FOR SEVERE WEATHER PARAMETERS. A
VALUE OVER 80 CORRESPONDS WITH A GOOD CHANCE FOR SEVERE WEATHER IN
THAT AREA. WE CONTINUE TO SEE VALUES IN THE 80S OVER SOUTHERN WI 18Z
MONDAY TO 06Z TUESDAY. IF THE ATMOSPHERE CAN RECOVER FROM ANY
OVERNIGHT CONVECTION IN TIME...THEN SURFACE-BASED SEVERE STORMS WILL
BE LIKELY. LARGE HAIL...STRONG WINDS AND TORNADOES WOULD ALL BE
POSSIBLE. STAY TUNED TO THE FORECAST.
.SHORT TERM...MONDAY NIGHT THROUGH WEDNESDAY.
MONDAY NIGHT AND TUESDAY...FORECAST CONFIDENCE MEDIUM.
TIMING CONTINUES TO BE EVERYTHING WITH THE SERIES OF SHORT
WAVES/VORT MAXES/PERTURBATIONS...ROUNDING THE BASE OF THE CLOSED LOW
CENTERED NEAR THE DAKOTAS/MINNESOTA BORDER AND LIFTING NORTH
THROUGH THE REGION...THAT WILL BE THE TRIGGERING MECHANISMS FOR
SHOWERS AND THUNDERSTORMS.
ONGOING CONVECTION WILL BE TAPERING OFF...WITH INCREASING
CONVERGENCE AHEAD OF NEXT 850 MB SPEED MAX ASSOCIATED WITH ANOTHER
SHORT WAVE APPROACHING BETWEEN 06Z AND 12Z TUESDAY. WHILE BETTER
POTENTIAL FOR SEVERE APPEARS TIED TO STRONGER FORCING FOCUSING TO
THE SOUTHWEST...STILL LIKELY TO SEE THUNDER...WITH ELEVATED CAPE
BETWEEN 600 AND 1000 J/KG.
CWASP FOR ALL MODELS SHIFTS HIGHER PERCENTAGES TO THE SOUTH FOR
TUESDAY...BUT GFS/GEM AND TO SOME EXTENT THE ECMWF STILL HAVE HIGH
ENOUGH VALUES TO CONTINUE PROBABILITY OF SEVERE INTO TUESDAY.
TUESDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE MEDIUM.
THREAT FOR WIDESPREAD THUNDERSTORMS TAPERS OFF OVERNIGHT INTO
WEDNESDAY AS FOCUS OF LOW-LEVEL JET SHIFTS SOUTHEAST AS CLOSED
SYSTEM SHIFTS TO THE EAST TOWARD WISCONSIN...AND CONVECTIVE
PARAMETERS DIMINISH. A BLENDED SOLUTION TO BALANCE TIMING
DIFFERENCES KEEPS LIKELY THUNDER IN THE EASTERN CWA...MAINLY IN THE
MORNING...WITH CHANCES FOR SHOWERS IN THE WEST.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. FORECAST CONFIDENCE
ALL THE MODELS SHIFT THE SURFACE LOW FAR ENOUGH EAST BY WEDNESDAY
NIGHT FOR COOL NORTHERLY WINDS TO PUSH IN. WILL HAVE TO KEEP CHANCES
OF SHOWERS IN THE FORECAST UNTIL 500 MB TROUGH CLEARS SOUTHERN
WISCONSIN THURSDAY EVENING. RIDGING BUILDS IN WITH OMEGA BLOCK
SETTING UP BRINGING DRY WEATHER AND BELOW NORMAL TEMPERATURES INTO
SATURDAY. THE CHANCE FOR SHOWERS AND THUNDERSTORMS RETURNS FOR
SATURDAY NIGHT AND SUNDAY WITH WARM AIR TRYING TO PUSH INTO THE
WESTERN GREAT LAKES AS EASTERN LOW SHIFTS AWAY AND SHORT WAVE
ENERGY EJECTING FROM WESTERN TROUGH BREAKS DOWN RIDGE.
&&
.AVIATION/00Z TAFS/...
THUNDERSTORMS IN SOUTH CENTRAL WI WILL DRIFT NORTHEAST AND
DISSIPATE LATE THIS AFTERNOON. ANOTHER BROKEN LINE OF
THUNDERSTORMS OVER NORTHEAST IOWA ARE EXPECTED TO TRACK INTO SOUTH
CENTRAL WI AROUND 23Z PER MESOSCALE MODELS. THEN ANOTHER ROUND OF
CONVECTION IS LOOKING MORE LIKELY FOR AFTER MIDNIGHT
TONIGHT...WHICH WOULD PROBABLY CLEAR SOUTHEAST WI EARLY MONDAY
MORNING. THUNDERSTORMS WILL HAVE THE POTENTIAL FOR STRONG WINDS
AND HAIL TONIGHT.
BEST CHANCE FOR SEVERE THUNDERSTORMS WITH A WIND/HAIL/TORNADO THREAT
IS LOOKING LIKE MONDAY AFTERNOON. SEE THE DISCUSSION ABOVE FOR
DETAILS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TONIGHT/MONDAY AND AVIATION/MARINE...MRC
MONDAY NIGHT THROUGH SUNDAY...REM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
220 PM CDT SUN MAY 19 2013
.SHORT TERM...(TONIGHT AND MONDAY)
ISSUED AT 220 PM CDT SUN MAY 19 2013
UPPER LEVEL SHORTWAVE TROUGH SERVING AS ONE FOCUS FOR STORM
DEVELOPMENT EARLY THIS AFTERNOON. SKIES HAVE CLEARED AHEAD OF THE
SHORTWAVE...MOVING NORTH/NORTHEAST ACROSS IOWA...ALLOWING FOR RAPID
DESTABILIZATION OF THE ATMOSPHERE. MUCAPES PER LATEST RAP ANALYSIS
HAVE RISEN INTO THE 2-3 K J/KG RANGE...WITH 30-40 KTS OF EFFECTIVE
SHEAR. SUPERCELL DEVELOPMENT IS SUPPORTED. SEE A POTENTIAL FOR ALL
SEVERE WEATHER TYPES...WITH SUPERCELLS MORPHING INTO BOWING
SEGMENTS. THINK DAMAGING WINDS MIGHT BECOME THE GREATER THREAT LATER
THIS AFTERNOON AND EVENING.
HRRR SUGGESTS THERE WILL BE ANOTHER ROUND OF STRONG/SEVERE STORMS
COMING IN TOWARD 06S AS A SHORTWAVE PUSHES NORTHWARD ACROSS IOWA.
INSTABILITY WOULD DECREASE WITH THE LOSS OF DAYTIME HEATING...BUT
GFS/NAM STILL SUGGEST 1000+ J/KG OF MUCAPE AT 06Z...WITH 40+ KTS OF
0-6 KM SHEAR. PLENTY TO CONTINUE A SEVERE THREAT.
FOR MONDAY...ATMOSPHERE PROGGED TO RELOAD FOR THE AFTERNOON/EVENING
WITH MUCAPES UPWARDS OF 2500 J/KG AND MLCAPES UP TO 2000 J/KG. 0-6KM
WIND SHEAR CLIMBS TO 40-50 KTS BY 00Z TUE...SUPPORTIVE OF SUPERCELL
DEVELOPMENT. 0-1KM SHEAR IS 15-20 KTS. IF ALL THIS COMES TO
PASS...ATMOSPHERE WOULD BE RIPE FOR SEVERE WEATHER...WITH ROTATING
SUPERCELLS AND THE GAMBIT OF SEVERE THREATS. THE KEY IS THE
KICKER...AND THAT IS WHERE THE FORECAST CHALLENGE LIES. GFS/NAM
SUGGEST A SHORTWAVE TROUGH COULD LIFT OUT OF THE BASE OF THE UPPER
LEVEL TROUGH FOR THE AFTERNOON/EVENING...BUT ALSO POINT TO POSSIBLE
MCVS SPINNING INTO THE REGION. MEANWHILE...THERE WILL LIKELY BE LEFT
OVER SFC BOUNDARIES FROM CONVECTION TODAY/TONIGHT. WHERE THESE LIE
IS UNKNOWN. CONFIDENCE IS NOT HIGH IN WHERE/WHEN CONVECTION WILL
FIRE...BUT BELIEVE THE LATE AFTERNOON/EVENING WOULD BE THE FAVORED
TIME FOR A SEVERE THREAT...AND GENERALLY FROM CENTRAL WI INTO
NORTHEAST IA.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 220 PM CDT SUN MAY 19 2013
THE VIRTUALLY STATIONARY UPPER LEVEL LOW FINALLY STARTS TO MAKE ITS
WAY EAST OUT OF THE NORTHERN PLAINS TUE...PER LATEST GFS/NAM/EC. THE
LOW WEAKENS SOME AS IT SLIDES OVER THE UPPER MISSISSIPPI RIVER
VALLEY TUE NIGHT/WED. MAIN COLD FRONT WITH THIS SYSTEM LOOKS LIKE IT
WILL SLIP THROUGH WITH THE LOW AROUND WED...BUT MODELS KEEP
CONVECTION AT A MINIMUM AROUND IT. RATHER...THE PCPN FOCUS IS
WITH THE LOW LEVEL MOISTURE TRANSPORT...WHICH IS WELL EAST OF THE
COLD FRONT...WRAPPING NORTH/WEST OF THE LOW. SOME MODEL DISAGREEMENT
WITH HOW FAR SOUTH THE AREAS OF SHOWERS/ISOLD STORMS WOULD REACH
WED...WITH THE GFS MORE SOUTH THAN THE EC. IT REMAINS A MESSY
SCENARIO WITH CLARITY LACKING...BUT TRENDS FAVOR THE GREATER PCPN
CHANCES OVER THE NORTHERN 1/2 OF THE FORECAST AREA. WILL LEAN ON
MODEL CONSENSUS FOR THE CHANCES.
TURNING BACK TO TUE...MUCAPES BUILD TO 1500+ J/KG OVER THE EASTERN
1/2 OF THE FORECAST DURING THE AFTERNOON...WITH 0-6 KM SHEAR OF
30-40 KTS. SOME SUGGESTIONS IN THE GFS/NAM OF A PIECE OF UPPER LEVEL
ENERGY ROTATING AROUND THE LOW...WHICH COULD SERVE AS A FOCUS FOR
SHOWER/STORM DEVELOPMENT. ATMOSPHERE LOOKS GOOD FOR STORM PRODUCTION
IF A SPARK FOR CONVECTION IS THERE...WITH A SEVERE THREAT IN THE
EAST TUE AFTERNOON/EARLY EVENING. AGAIN...KEY HERE IS WHERE THE PCPN
FOCUSES WILL BE...INCLUDING ANY MESO SCALE BOUNDARIES AND/OR MCVS
LEFT FROM PREVIOUS CONVECTION.
BETTER AGREEMENT BETWEEN THE GFS AND ECMWF WITH PUSHING THAT
LINGERING LOW EAST/SOUTHEAST ON THU...ALLOWING AN UPPER LEVEL SFC
RIDGE/HIGH PRESSURE SYSTEM TO BUILD INTO THE REGION. SHOULD GET A
COUPLE DRIER DAYS AS A RESULT. HOWEVER...WARM/MOIST AIR ON THE
BACKSIDE OF THE HIGH COUPLED WITH A BIT OF UPPER LEVEL ENERGY COULD
RETURN SOME SHOWERS/STORMS TO THE REGION SAT-SUN.
&&
.AVIATION...THROUGH 18Z MONDAY
1236 PM CDT SUN MAY 19 2013
MAIN AVIATION CONCERNS ARE SHOWERS/THUNDERSTORMS DEVELOPMENT AND
MOVEMENT INTO RST/LSE TAF SITES AND THE SEVERE POTENTIAL WITH
THUNDERSTORMS THIS AFTERNOON INTO THE EVENING HOURS. THE 19.12Z
NAM AND 19.15Z RAP MODELS CONTINUE TO SHOW DECENT SOUTHERLY
MOISTURE FLOW INTO THE AREA. BOTH MODELS INDICATE A COUPLE OF UPPER
LEVEL DISTURBANCES TO TRACK INTO THE REGION THIS AFTERNOON AND
EVENING. THE COMBINATION OF SOUTHERLY MOISTURE FLOW...INSTABILITY AND
LIFT IN ASSOCIATION WITH THE UPPER LEVEL DISTURBANCES WILL ALLOW
FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON.
UNCERTAINTY STILL EXIST AT TIMING OF CONVECTION OVER THE REGION
THIS AFTERNOON. HAVE DELAYED TIMING OF VCTS AT BOTH TAF SITES AND
ADDED TEMPO GROUP FOR THUNDERSTORMS LATE THIS AFTERNOON AND
EVENING. THE POTENTIAL FOR SEVERE THUNDERSTORMS EXIST AT BOTH TAF
SITES MAINLY AFTER 20Z SUNDAY TO AROUND 03Z MONDAY...DUE TO
INCREASING INSTABILITY AND WIND SHEAR OVER THE AREA. BOTH THE 19.12Z
NAM/19.15Z RAP INDICATE FOCUS OF SOUTHERLY MOISTURE FLOW OVER
CENTRAL AND EASTERN WISCONSIN AFTER 06Z MONDAY AND SHOULD PUSH
THUNDERSTORM ACTIVITY EAST OF THE RST/LSE TAF SITES. LINGERING
RAIN SHOWERS WILL CONTINUE AT BOTH TAF SITES TO AROUND 11Z AND 13Z
MONDAY. IN ADDITION...LATEST BUFKIT SOUNDINGS FROM THE 19.12Z NAM
AND 19.15Z SUGGEST CEILINGS IN THE MVFR RANGE WITH THE RAIN AND
CONVECTION. HAVE INTRODUCED MVFR RANGE CEILINGS AFTER 03Z AND 06Z
AT TAF SITES.
&&
.HYDROLOGY...
ISSUED AT 220 PM CDT SUN MAY 19 2013
FLASH FLOOD WATCH THROUGH MONDAY AFTERNOON FOR PARTS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA.
SOAKING RAINS AND HIGH SOIL MOISTURE FROM A WET SPRING HAS PRIMED
THIS AREA FOR FLASH FLOODING. A SLOW MOVING LOW PRESSURE SYSTEM WILL
PRODUCE PERIODS OF SHOWERS AND THUNDERSTORMS FOR THE NEXT FEW
DAYS...WITH 1 TO 2 INCHES POSSIBLE INTO MONDAY NIGHT. PWS ARE AROUND
150 PERCENT OR NORMAL...OR GREATER...THROUGH THIS PERIOD. ANY HEAVY
RAINFALL...ESPECIALLY IN A SHORT PERIOD OF TIME...WOULD LIKELY
RESULT IN AT LEAST LOCALIZED FLOODING ISSUES...POTENTIALLY MORE
WIDESPREAD.
THIS FLASH FLOOD WATCH MAY BE EXPANDED AND POSSIBLY EXTENDED INTO
MONDAY NIGHT...DEPENDING ON WHAT HAPPENS TODAY...AND IF DETAILS
SUGGEST THE FLOODING THREAT COULD REMAIN.
HOWEVER...MODELS PROVIDE SOME HOPE THAT THE HEAVIER RAIN THREAT
COULD SHIFT NORTH/EAST AS THE OFFENDING LOW PRESSURE SYSTEM INCHES
CLOSER FROM THE WEST. RELATIVELY DRIER AIR FROM THE ROCKIES/PLAINS
WOULD PUSH IN FROM THE SOUTHWEST...WHILE THE WARM/MOIST CONVEYOR
BELT WOULD MOVE INTO WI AND NUDGED NORTH.
RIVERS IN THE WATCH AREA WOULD ALSO SEE RAPID RISES ASIDE FROM THE
FLASH FLOODING EFFECTS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH THROUGH MONDAY
EVENING FOR MNZ079-086-087-094-095.
IA...FLASH FLOOD WATCH THROUGH MONDAY
EVENING FOR IAZ008.
&&
$$
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....WETENKAMP
HYDROLOGY....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1237 PM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 318 AM CDT SUN MAY 19 2013
IT STILL APPEARS AMPLE INSTABILITY WILL BE AROUND BY AFTERNOON
OVER THE FORECAST AREA....HOWEVER A CLEAR TRIGGER AND FOCUS FOR
THUNDERSTORMS AND SEVERE WEATHER IS STILL NOT CLEAR.
AT 08Z THE HIGH PLAINS CONVECTION CONTINUES TO SHIFT EAST ACROSS
IA...BEING FUELED BY A MARITIME TROPICAL AIR MASS SURGE AS
PRESSURES FALL IN RESPONSE TO THE INITIAL SHORTWAVE TROUGH
EJECTING NORTH FROM THE LONG WAVE TROUGH OVER THE INTERMOUNTAIN.
CURRENTLY THE TROUGH IS OVER NERN CO PER GOES WATER VAPOR IMAGERY.
ANOTHER PIECE OF ENERGY IS OVER THE WRN TX PANHANDLE AND WILL
ARRIVE THIS EVENING. 00Z RAOB DATA INDICATES THAT MARITIME
TROPICAL AIR MASS WELL...WITH AN AXIS OF 1.25 TO 1.50 INCH
PRECIPITABLE WATER VALUES FROM OMAHA TO SPRINGFIELD /170 PERCENT
NORMAL/. THIS IS COMPARED TO 1.00 TO 1.25 INCHES MSP-DVN. THIS AIR
MASS ARRIVES OVER THE FORECAST AREA TODAY WITH SURFACE DEWPOINTS
THE HIGHEST OF THE YEAR...IN THE MIDDLE TO UPPER 60S. 88D WIND
PROFILERS SHOWING AN INCREASING LOW- LEVEL JET ACROSS
IA...CONVERGING INTO MN. THIS TRAJECTORY IS NOT LIFTING
ADIABATICALLY HOWEVER...WITH LITTLE TEMPERATURE GRADIENT THROUGH
THAT AREA. THE CONVERGENCE AND INSTABILITY IS FUELING THE STORMS.
A FEW WARNINGS HAVE BEEN ISSUED RECENTLY FOR HAIL. WIND SHEAR IS
WEAKER SO ISOLATED LARGE HAIL IS REALLY ALL WE WOULD EXPECT.
HAVE BEEN MONITORING THE HRRR RUNS ALL EVENING AND UNTIL THE
19.03Z RUN...A VERY CONSISTENT SIGNAL WAS PRESENT OF BRINGING THE
CONVECTION INTO THE WRN FORECAST AREA AROUND 12Z. HAVE SLOWLY
STEPPED UP THE RAIN CHANCES BASED ON THE LOW-LEVEL JET AND
MOISTURE TRANSPORT CONVERGENCE IN CONCERT WITH INCREASING CAPE AS
THAT MOIST AIR MASS BEGINS ITS INFLUENCE. CURRENTLY MUCAPES OF
AROUND 1000 J/KG ARE WEST OF THE MISS RIVER...BUT THIS IS LIKELY
TO INCREASE OVERNIGHT AND PROBABLY BE IN THE 1300 J/KG RANGE BY
DAWN.
THE MOISTURE SURGE AND TRANSPORT SHIFT NORTHWARD AND BEGIN WHAT
APPEARS TO BE A LONGER TERM FOCUS OF CONVERGENCE NORTHWEST OF THE
FORECAST AREA. THIS AFTERNOON IT APPEARS THE MODEL GUIDANCE IS
CONSISTENT IN A FAIRLY UNIFORM SOUTHEAST FLOW OVER THE FORECAST
AREA...WITH CONVERGENCE ACROSS NRN WI TO CENTRAL MN...ALONG THE
STATIONARY BOUNDARY. WITH VERY HIGH MOISTURE IN PLACE AND SOME
HEATING...WE WILL BUILD SOME HIGHER MLCAPES AROUND 1800 J/KG
QUICKLY /MAYBE 3000 J/KG SBCAPE/. THIS USING A 67F DEWPOINT.
THE WIND SHEAR OVER THE AREA HAS BEEN CONSISTENTLY FORECAST BELOW
SUPERCELL THRESHOLDS THIS AFTERNOON WITH MOST OF THE SHEAR A
MODERATE 30-35KTS FROM 0-3KM AND LITTLE INCREASE ABOVE. THIS WOULD
FAVOR COLD POOL SYSTEMS AND BOWING WIND SEGMENTS. THE 19.00Z NAM
IS A BIT OF AN OUTLIER SUGGESTING STRONGER WINDS ALOFT FURTHER
NORTH...IN THE SUPERCELL RANGE. HAVE STAYED THE COURSE WITH A
WEAKER GRADIENT ALOFT WITH THE LOW CENTER STILL FAR WEST. SO THE
THREATS CONTINUE TO BE DAMAGING WIND AND LARGE HAIL. FLASH
FLOODING COULD ALSO BE A PROBLEM...SEE HYDROLOGY SECTION. AN
ISOLATED TORNADO IS POSSIBLE TOO.
THE MAIN PROBLEM RIGHT NOW SEEMS TO BE THE LACK OF A GOOD TRIGGER
THIS AFTERNOON. THE BOUNDARY LAYER FLOW IS A UNIFORM SOUTHEAST AND
LITTLE CONVERGENCE IS SEEN IN THE AREA. THUS...ANY BOUNDARY THAT
DOES PRESENT ITSELF COULD TRIGGER INITIATION AS THERE WILL BE NO
CAP IN PLACE. WITH SUCH VIGOROUS CONVECTION IN KS/OK...UPSTREAM OF
THE AREA...WE COULD SEE A CONVECTIVE VORTICITY MAX APPEAR IN THE
FLOW AND POSSIBLY BECOME AN INITIATOR. THE HRRR AND HI RES NMM SEEM
TO BE HINTING AT THIS SOLUTION LATER AFTERNOON.
THIS EVENING...AS STRONG ENERGY ROTATES NORTHEAST...CURRENTLY IN
WEST TX...THE LOW-LEVEL JET IN THE 19.00Z NAM EXCITES AND A NICE
CONVERGENT LOW-LEVEL JET DEVELOPS CONVECTION OVER IOWA AND MOVES
IT NORTHWARD. THE 19.00Z GFS DOES NOT AGREE ON THIS WITH ITS FOCUS
NORTH AGAIN ON THE NWRN WI-CENTRAL MN BOUNDARY. BUT THE HI RES 00Z
RUNS...USING THE NAM AS INITIALIZATION AND BOUNDARY
CONDITIONS...BRING WIDESPREAD CONVECTION IN FROM IA. THERE IS
BETTER JET DYNAMICS AND TRANSPORT IN THE NAM..AND THIS SEEMS
REASONABLE...THUS..HAVE CONTINUED TO HIT THE EVENING
HARD...EVOLVING THE WEATHER NORTH BY MORNING. THE 19.00Z GEM AND ECMWF
AGREE WELL WITH THIS SCENARIO. SO...LOOKING FOR A WET OVERNIGHT.
THERE IS STILL INSTABILITY OVERNIGHT...2K MUCAPE...AND A BIT
BETTER SHEAR.
BOTTOM LINE IS THAT THE DAYTIME HOURS MAY BE PRETTY CLEAN BECAUSE
OF LACK OF A THUNDERSTORM TRIGGER. IF AN MCV FROM OK/KS CAN
DEVELOP TSRA AND THE TSRA CAN ROOT ITSELF IN THE BOUNDARY LAYER
OVER IA...OR SOME BOUNDARY EXISTS...CHANCES INCREASE FOR AFTERNOON
SEVERE WEATHER...AS THE AIR MASS WILL BE WEAKLY CAPPED. THIS
EVENING SEEMS TO PROMOTE INCREASING RAIN AND THUNDERSTORMS WITH
STILL SOME SEVERE POTENTIAL UNTIL THE CAPE IS USED UP...BUT NOT
QUITE AS WIDESPREAD AS AN AFTERNOON EVENT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 318 AM CDT SUN MAY 19 2013
AS THE LOW DRAWS CLOSER MONDAY...SHEAR INCREASES TO SUPERCELL
STRENGTH...BUT AGAIN IT MAY BE DIFFICULT TO IDENTIFY A TRIGGER
WITH LITTLE SURFACE BOUNDARY ACTION IN THE AREA. THE STATIONARY
BOUNDARY REMAINS TO THE NW WITH THE BEST CONVERGENCE. HOWEVER...WITH
THE SURFACE LOW EXPECTED TO BE NEAR KFSD...AND AMPLE MLCAPE AGAIN
NEAR 2000 J/KG...STORMS LOOK TO FORM TO THE WEST AND MOVE INTO THE
AREA TUESDAY EVENING. HOWEVER...THIS PATTERN IS SO UNCAPPED AND
UNSTABLE...WE FOUND IT HARD TO GET DETAILED ON TIMING ANYWHERE.
MONDAY STILL HAS THE POTENTIAL FOR SEVERE WEATHER...AND IT LOOKS
LIKE THE EVENING HOURS. WITH INCREASED WIND SHEAR...ROTATING
STORMS ARE POSSIBLE AND THUS LARGE HAIL AND WIND. AN ISOLATED
TORNADO CANNOT BE RULED OUT BUT THE WIND ENVIRONMENT DOESNT LOOK
OVERLY FAVORABLE.
THE LOW CONTINUES TO SHIFT SLOWLY EAST AND PROVIDE RAIN THREATS
THAT ARE DIFFICULT TO TARGET THROUGH THURSDAY. SOME DRIER AIR BEGINS TO
SHIFT INTO THE AREA ON SOUTHWEST FLOW OFF THE ROCKIES ON
TUESDAY...AND SOMEWHAT COOLER AIR. THIS WILL END THE SEVERE
WEATHER THREAT.
&&
.AVIATION...THROUGH 18Z MONDAY
1236 PM CDT SUN MAY 19 2013
MAIN AVIATION CONCERNS ARE SHOWERS/THUNDERSTORMS DEVELOPMENT AND
MOVEMENT INTO RST/LSE TAF SITES AND THE SEVERE POTENTIAL WITH
THUNDERSTORMS THIS AFTERNOON INTO THE EVENING HOURS. THE 19.12Z
NAM AND 19.15Z RAP MODELS CONTINUE TO SHOW DECENT SOUTHERLY
MOISTURE FLOW INTO THE AREA. BOTH MODELS INDICATE A COUPLE OF UPPER
LEVEL DISTURBANCES TO TRACK INTO THE REGION THIS AFTERNOON AND
EVENING. THE COMBINATION OF SOUTHERLY MOISTURE FLOW...INSTABILITY AND
LIFT IN ASSOCIATION WITH THE UPPER LEVEL DISTURBANCES WILL ALLOW
FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON.
UNCERTAINTY STILL EXIST AT TIMING OF CONVECTION OVER THE REGION
THIS AFTERNOON. HAVE DELAYED TIMING OF VCTS AT BOTH TAF SITES AND
ADDED TEMPO GROUP FOR THUNDERSTORMS LATE THIS AFTERNOON AND
EVENING. THE POTENTIAL FOR SEVERE THUNDERSTORMS EXIST AT BOTH TAF
SITES MAINLY AFTER 20Z SUNDAY TO AROUND 03Z MONDAY...DUE TO
INCREASING INSTABILITY AND WIND SHEAR OVER THE AREA. BOTH THE 19.12Z
NAM/19.15Z RAP INDICATE FOCUS OF SOUTHERLY MOISTURE FLOW OVER
CENTRAL AND EASTERN WISCONSIN AFTER 06Z MONDAY AND SHOULD PUSH
THUNDERSTORM ACTIVITY EAST OF THE RST/LSE TAF SITES. LINGERING
RAIN SHOWERS WILL CONTINUE AT BOTH TAF SITES TO AROUND 11Z AND 13Z
MONDAY. IN ADDITION...LATEST BUFKIT SOUNDINGS FROM THE 19.12Z NAM
AND 19.15Z SUGGEST CEILINGS IN THE MVFR RANGE WITH THE RAIN AND
CONVECTION. HAVE INTRODUCED MVFR RANGE CEILINGS AFTER 03Z AND 06Z
AT TAF SITES.
&&
.HYDROLOGY...
ISSUED AT 318 AM CDT SUN MAY 19 2013
HYDROLOGY...THE PROBABILITIES HAVE TIPPED TOWARD A FLASH FLOOD WATCH
FOR 3 PM TODAY THROUGH MONDAY. THERE ARE TOO MANY VARIABLES IN
PLAY THAT SUGGEST HEAVY RAINFALL AND FLOODING POTENTIAL INCLUDING
SOIL MOISTURE CENTERED OVER SERN MN ABNORMALLY HIGH...FRIDAYS
RAINFALL HAVING HIGHER END FLOODING OUTCOMES IN SERN
MN...PRECIPITABLE WATER VALUES OVER 150 PERCENT NORMAL MOVING
IN...SBCAPE BUILDING DURING THE DAY TO NEAR 3K /ML NEAR 1800/
BASED ON 67F DEW POINT...AND FORCING INCREASING DURING THE EVENING
WITH STRONGER MOISTURE TRANSPORT CONVERGENCE AND SHEAR MOVING INTO
THE AREA.
THIS FLASH FLOOD WATCH MAY BE EXPANDED AND POSSIBLY EXTENDED INTO
MONDAY NIGHT SHOULD DETAILS SUGGEST THE FLOODING THREAT COULD
REMAIN. THERE IS SOME SUGGESTION THAT THE VERY HIGH PRECIPITABLE
WATER MOIST CONVEYOR BELT WOULD SHIFT INTO WI AS A DRIER ROCKIES AIR
MASS ADVECTS IN ON SWRLY FLOW.
RIVERS IN THE WATCH AREA WOULD ALSO SEE RAPID RISES ASIDE FROM THE
FLASH FLOODING EFFECTS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH FROM 3 PM CDT THIS AFTERNOON THROUGH MONDAY
EVENING FOR MNZ079-086-087-094-095.
IA...FLASH FLOOD WATCH FROM 3 PM CDT THIS AFTERNOON THROUGH MONDAY
EVENING FOR IAZ008.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...DTJ
HYDROLOGY...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
647 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 318 AM CDT SUN MAY 19 2013
IT STILL APPEARS AMPLE INSTABILITY WILL BE AROUND BY AFTERNOON
OVER THE FORECAST AREA....HOWEVER A CLEAR TRIGGER AND FOCUS FOR
THUNDERSTORMS AND SEVERE WEATHER IS STILL NOT CLEAR.
AT 08Z THE HIGH PLAINS CONVECTION CONTINUES TO SHIFT EAST ACROSS
IA...BEING FUELED BY A MARITIME TROPICAL AIR MASS SURGE AS
PRESSURES FALL IN RESPONSE TO THE INITIAL SHORTWAVE TROUGH
EJECTING NORTH FROM THE LONG WAVE TROUGH OVER THE INTERMOUNTAIN.
CURRENTLY THE TROUGH IS OVER NERN CO PER GOES WATER VAPOR IMAGERY.
ANOTHER PIECE OF ENERGY IS OVER THE WRN TX PANHANDLE AND WILL
ARRIVE THIS EVENING. 00Z RAOB DATA INDICATES THAT MARITIME
TROPICAL AIR MASS WELL...WITH AN AXIS OF 1.25 TO 1.50 INCH
PRECIPITABLE WATER VALUES FROM OMAHA TO SPRINGFIELD /170 PERCENT
NORMAL/. THIS IS COMPARED TO 1.00 TO 1.25 INCHES MSP-DVN. THIS AIR
MASS ARRIVES OVER THE FORECAST AREA TODAY WITH SURFACE DEWPOINTS
THE HIGHEST OF THE YEAR...IN THE MIDDLE TO UPPER 60S. 88D WIND
PROFILERS SHOWING AN INCREASING LOW- LEVEL JET ACROSS
IA...CONVERGING INTO MN. THIS TRAJECTORY IS NOT LIFTING
ADIABATICALLY HOWEVER...WITH LITTLE TEMPERATURE GRADIENT THROUGH
THAT AREA. THE CONVERGENCE AND INSTABILITY IS FUELING THE STORMS.
A FEW WARNINGS HAVE BEEN ISSUED RECENTLY FOR HAIL. WIND SHEAR IS
WEAKER SO ISOLATED LARGE HAIL IS REALLY ALL WE WOULD EXPECT.
HAVE BEEN MONITORING THE HRRR RUNS ALL EVENING AND UNTIL THE
19.03Z RUN...A VERY CONSISTENT SIGNAL WAS PRESENT OF BRINGING THE
CONVECTION INTO THE WRN FORECAST AREA AROUND 12Z. HAVE SLOWLY
STEPPED UP THE RAIN CHANCES BASED ON THE LOW-LEVEL JET AND
MOISTURE TRANSPORT CONVERGENCE IN CONCERT WITH INCREASING CAPE AS
THAT MOIST AIR MASS BEGINS ITS INFLUENCE. CURRENTLY MUCAPES OF
AROUND 1000 J/KG ARE WEST OF THE MISS RIVER...BUT THIS IS LIKELY
TO INCREASE OVERNIGHT AND PROBABLY BE IN THE 1300 J/KG RANGE BY
DAWN.
THE MOISTURE SURGE AND TRANSPORT SHIFT NORTHWARD AND BEGIN WHAT
APPEARS TO BE A LONGER TERM FOCUS OF CONVERGENCE NORTHWEST OF THE
FORECAST AREA. THIS AFTERNOON IT APPEARS THE MODEL GUIDANCE IS
CONSISTENT IN A FAIRLY UNIFORM SOUTHEAST FLOW OVER THE FORECAST
AREA...WITH CONVERGENCE ACROSS NRN WI TO CENTRAL MN...ALONG THE
STATIONARY BOUNDARY. WITH VERY HIGH MOISTURE IN PLACE AND SOME
HEATING...WE WILL BUILD SOME HIGHER MLCAPES AROUND 1800 J/KG
QUICKLY /MAYBE 3000 J/KG SBCAPE/. THIS USING A 67F DEWPOINT.
THE WIND SHEAR OVER THE AREA HAS BEEN CONSISTENTLY FORECAST BELOW
SUPERCELL THRESHOLDS THIS AFTERNOON WITH MOST OF THE SHEAR A
MODERATE 30-35KTS FROM 0-3KM AND LITTLE INCREASE ABOVE. THIS WOULD
FAVOR COLD POOL SYSTEMS AND BOWING WIND SEGMENTS. THE 19.00Z NAM
IS A BIT OF AN OUTLIER SUGGESTING STRONGER WINDS ALOFT FURTHER
NORTH...IN THE SUPERCELL RANGE. HAVE STAYED THE COURSE WITH A
WEAKER GRADIENT ALOFT WITH THE LOW CENTER STILL FAR WEST. SO THE
THREATS CONTINUE TO BE DAMAGING WIND AND LARGE HAIL. FLASH
FLOODING COULD ALSO BE A PROBLEM...SEE HYDROLOGY SECTION. AN
ISOLATED TORNADO IS POSSIBLE TOO.
THE MAIN PROBLEM RIGHT NOW SEEMS TO BE THE LACK OF A GOOD TRIGGER
THIS AFTERNOON. THE BOUNDARY LAYER FLOW IS A UNIFORM SOUTHEAST AND
LITTLE CONVERGENCE IS SEEN IN THE AREA. THUS...ANY BOUNDARY THAT
DOES PRESENT ITSELF COULD TRIGGER INITIATION AS THERE WILL BE NO
CAP IN PLACE. WITH SUCH VIGOROUS CONVECTION IN KS/OK...UPSTREAM OF
THE AREA...WE COULD SEE A CONVECTIVE VORTICITY MAX APPEAR IN THE
FLOW AND POSSIBLY BECOME AN INITIATOR. THE HRRR AND HI RES NMM SEEM
TO BE HINTING AT THIS SOLUTION LATER AFTERNOON.
THIS EVENING...AS STRONG ENERGY ROTATES NORTHEAST...CURRENTLY IN
WEST TX...THE LOW-LEVEL JET IN THE 19.00Z NAM EXCITES AND A NICE
CONVERGENT LOW-LEVEL JET DEVELOPS CONVECTION OVER IOWA AND MOVES
IT NORTHWARD. THE 19.00Z GFS DOES NOT AGREE ON THIS WITH ITS FOCUS
NORTH AGAIN ON THE NWRN WI-CENTRAL MN BOUNDARY. BUT THE HI RES 00Z
RUNS...USING THE NAM AS INITIALIZATION AND BOUNDARY
CONDITIONS...BRING WIDESPREAD CONVECTION IN FROM IA. THERE IS
BETTER JET DYNAMICS AND TRANSPORT IN THE NAM..AND THIS SEEMS
REASONABLE...THUS..HAVE CONTINUED TO HIT THE EVENING
HARD...EVOLVING THE WEATHER NORTH BY MORNING. THE 19.00Z GEM AND ECMWF
AGREE WELL WITH THIS SCENARIO. SO...LOOKING FOR A WET OVERNIGHT.
THERE IS STILL INSTABILITY OVERNIGHT...2K MUCAPE...AND A BIT
BETTER SHEAR.
BOTTOM LINE IS THAT THE DAYTIME HOURS MAY BE PRETTY CLEAN BECAUSE
OF LACK OF A THUNDERSTORM TRIGGER. IF AN MCV FROM OK/KS CAN
DEVELOP TSRA AND THE TSRA CAN ROOT ITSELF IN THE BOUNDARY LAYER
OVER IA...OR SOME BOUNDARY EXISTS...CHANCES INCREASE FOR AFTERNOON
SEVERE WEATHER...AS THE AIR MASS WILL BE WEAKLY CAPPED. THIS
EVENING SEEMS TO PROMOTE INCREASING RAIN AND THUNDERSTORMS WITH
STILL SOME SEVERE POTENTIAL UNTIL THE CAPE IS USED UP...BUT NOT
QUITE AS WIDESPREAD AS AN AFTERNOON EVENT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 318 AM CDT SUN MAY 19 2013
AS THE LOW DRAWS CLOSER MONDAY...SHEAR INCREASES TO SUPERCELL
STRENGTH...BUT AGAIN IT MAY BE DIFFICULT TO IDENTIFY A TRIGGER
WITH LITTLE SURFACE BOUNDARY ACTION IN THE AREA. THE STATIONARY
BOUNDARY REMAINS TO THE NW WITH THE BEST CONVERGENCE. HOWEVER...WITH
THE SURFACE LOW EXPECTED TO BE NEAR KFSD...AND AMPLE MLCAPE AGAIN
NEAR 2000 J/KG...STORMS LOOK TO FORM TO THE WEST AND MOVE INTO THE
AREA TUESDAY EVENING. HOWEVER...THIS PATTERN IS SO UNCAPPED AND
UNSTABLE...WE FOUND IT HARD TO GET DETAILED ON TIMING ANYWHERE.
MONDAY STILL HAS THE POTENTIAL FOR SEVERE WEATHER...AND IT LOOKS
LIKE THE EVENING HOURS. WITH INCREASED WIND SHEAR...ROTATING
STORMS ARE POSSIBLE AND THUS LARGE HAIL AND WIND. AN ISOLATED
TORNADO CANNOT BE RULED OUT BUT THE WIND ENVIRONMENT DOESNT LOOK
OVERLY FAVORABLE.
THE LOW CONTINUES TO SHIFT SLOWLY EAST AND PROVIDE RAIN THREATS
THAT ARE DIFFICULT TO TARGET THROUGH THURSDAY. SOME DRIER AIR BEGINS TO
SHIFT INTO THE AREA ON SOUTHWEST FLOW OFF THE ROCKIES ON
TUESDAY...AND SOMEWHAT COOLER AIR. THIS WILL END THE SEVERE
WEATHER THREAT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 646 AM CDT SUN MAY 19 2013
A WEAKENING LINE OF SHOWERS AND A FEW THUNDERSTORMS WILL MOVE INTO
WESTERN WISCONSIN AROUND 19.12Z. THIS LINE IS NOT CAUSING ANY
VISIBILITY RESTRICTIONS OR A WIND SHIFT. IN ADDITION...THE
CEILINGS WILL REMAIN VFR. MESO MODELS SUGGEST THAT SEVERAL LINES
OF SHOWERS AND THUNDERSTORMS WILL MOVE THROUGH THE TAF SITES THIS
AFTERNOON AND TONIGHT. THE ONLY TIME PERIOD THAT SEEMS TO BE
CONSISTENT IN TIMING IS THE ONE THAT MOVES THROUGH BETWEEN 19.18Z
AND 19.21Z...SO INCLUDED SOME THUNDERSTORMS DURING THIS TIME
PERIOD. A FEW OF THESE STORMS MAY EVEN BECOME SEVERE WITH LARGE
HAIL AND DAMAGING WINDS BEING THE PRIMARY CONCERN. BEYOND THIS
TIME PERIOD...THE TIMING IS VERY INCONSISTENT...SO JUST WENT WITH
SHOWERS FOR NOW.
&&
.HYDROLOGY...
ISSUED AT 318 AM CDT SUN MAY 19 2013
HYDROLOGY...THE PROBABILITIES HAVE TIPPED TOWARD A FLASH FLOOD WATCH
FOR 3 PM TODAY THROUGH MONDAY. THERE ARE TOO MANY VARIABLES IN
PLAY THAT SUGGEST HEAVY RAINFALL AND FLOODING POTENTIAL INCLUDING
SOIL MOISTURE CENTERED OVER SERN MN ABNORMALLY HIGH...FRIDAYS
RAINFALL HAVING HIGHER END FLOODING OUTCOMES IN SERN
MN...PRECIPITABLE WATER VALUES OVER 150 PERCENT NORMAL MOVING
IN...SBCAPE BUILDING DURING THE DAY TO NEAR 3K /ML NEAR 1800/
BASED ON 67F DEW POINT...AND FORCING INCREASING DURING THE EVENING
WITH STRONGER MOISTURE TRANSPORT CONVERGENCE AND SHEAR MOVING INTO
THE AREA.
THIS FLASH FLOOD WATCH MAY BE EXPANDED AND POSSIBLY EXTENDED INTO
MONDAY NIGHT SHOULD DETAILS SUGGEST THE FLOODING THREAT COULD
REMAIN. THERE IS SOME SUGGESTION THAT THE VERY HIGH PRECIPITABLE
WATER MOIST CONVEYOR BELT WOULD SHIFT INTO WI AS A DRIER ROCKIES AIR
MASS ADVECTS IN ON SWRLY FLOW.
RIVERS IN THE WATCH AREA WOULD ALSO SEE RAPID RISES ASIDE FROM THE
FLASH FLOODING EFFECTS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH FROM 3 PM CDT THIS AFTERNOON THROUGH MONDAY
EVENING FOR MNZ079-086-087-094-095.
IA...FLASH FLOOD WATCH FROM 3 PM CDT THIS AFTERNOON THROUGH MONDAY
EVENING FOR IAZ008.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...BOYNE
HYDROLOGY...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
318 AM CDT SUN MAY 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 318 AM CDT SUN MAY 19 2013
IT STILL APPEARS AMPLE INSTABILITY WILL BE AROUND BY AFTERNOON
OVER THE FORECAST AREA....HOWEVER A CLEAR TRIGGER AND FOCUS FOR
THUNDERSTORMS AND SEVERE WEATHER IS STILL NOT CLEAR.
AT 08Z THE HIGH PLAINS CONVECTION CONTINUES TO SHIFT EAST ACROSS
IA...BEING FUELED BY A MARITIME TROPICAL AIR MASS SURGE AS
PRESSURES FALL IN RESPONSE TO THE INITIAL SHORTWAVE TROUGH
EJECTING NORTH FROM THE LONG WAVE TROUGH OVER THE INTERMOUNTAIN.
CURRENTLY THE TROUGH IS OVER NERN CO PER GOES WATER VAPOR IMAGERY.
ANOTHER PIECE OF ENERGY IS OVER THE WRN TX PANHANDLE AND WILL
ARRIVE THIS EVENING. 00Z RAOB DATA INDICATES THAT MARITIME
TROPICAL AIR MASS WELL...WITH AN AXIS OF 1.25 TO 1.50 INCH
PRECIPITABLE WATER VALUES FROM OMAHA TO SPRINGFIELD /170 PERCENT
NORMAL/. THIS IS COMPARED TO 1.00 TO 1.25 INCHES MSP-DVN. THIS AIR
MASS ARRIVES OVER THE FORECAST AREA TODAY WITH SURFACE DEWPOINTS
THE HIGHEST OF THE YEAR...IN THE MIDDLE TO UPPER 60S. 88D WIND
PROFILERS SHOWING AN INCREASING LOW- LEVEL JET ACROSS
IA...CONVERGING INTO MN. THIS TRAJECTORY IS NOT LIFTING
ADIABATICALLY HOWEVER...WITH LITTLE TEMPERATURE GRADIENT THROUGH
THAT AREA. THE CONVERGENCE AND INSTABILITY IS FUELING THE STORMS.
A FEW WARNINGS HAVE BEEN ISSUED RECENTLY FOR HAIL. WIND SHEAR IS
WEAKER SO ISOLATED LARGE HAIL IS REALLY ALL WE WOULD EXPECT.
HAVE BEEN MONITORING THE HRRR RUNS ALL EVENING AND UNTIL THE
19.03Z RUN...A VERY CONSISTENT SIGNAL WAS PRESENT OF BRINGING THE
CONVECTION INTO THE WRN FORECAST AREA AROUND 12Z. HAVE SLOWLY
STEPPED UP THE RAIN CHANCES BASED ON THE LOW-LEVEL JET AND
MOISTURE TRANSPORT CONVERGENCE IN CONCERT WITH INCREASING CAPE AS
THAT MOIST AIR MASS BEGINS ITS INFLUENCE. CURRENTLY MUCAPES OF
AROUND 1000 J/KG ARE WEST OF THE MISS RIVER...BUT THIS IS LIKELY
TO INCREASE OVERNIGHT AND PROBABLY BE IN THE 1300 J/KG RANGE BY
DAWN.
THE MOISTURE SURGE AND TRANSPORT SHIFT NORTHWARD AND BEGIN WHAT
APPEARS TO BE A LONGER TERM FOCUS OF CONVERGENCE NORTHWEST OF THE
FORECAST AREA. THIS AFTERNOON IT APPEARS THE MODEL GUIDANCE IS
CONSISTENT IN A FAIRLY UNIFORM SOUTHEAST FLOW OVER THE FORECAST
AREA...WITH CONVERGENCE ACROSS NRN WI TO CENTRAL MN...ALONG THE
STATIONARY BOUNDARY. WITH VERY HIGH MOISTURE IN PLACE AND SOME
HEATING...WE WILL BUILD SOME HIGHER MLCAPES AROUND 1800 J/KG
QUICKLY /MAYBE 3000 J/KG SBCAPE/. THIS USING A 67F DEWPOINT.
THE WIND SHEAR OVER THE AREA HAS BEEN CONSISTENTLY FORECAST BELOW
SUPERCELL THRESHOLDS THIS AFTERNOON WITH MOST OF THE SHEAR A
MODERATE 30-35KTS FROM 0-3KM AND LITTLE INCREASE ABOVE. THIS WOULD
FAVOR COLD POOL SYSTEMS AND BOWING WIND SEGMENTS. THE 19.00Z NAM
IS A BIT OF AN OUTLIER SUGGESTING STRONGER WINDS ALOFT FURTHER
NORTH...IN THE SUPERCELL RANGE. HAVE STAYED THE COURSE WITH A
WEAKER GRADIENT ALOFT WITH THE LOW CENTER STILL FAR WEST. SO THE
THREATS CONTINUE TO BE DAMAGING WIND AND LARGE HAIL. FLASH
FLOODING COULD ALSO BE A PROBLEM...SEE HYDROLOGY SECTION. AN
ISOLATED TORNADO IS POSSIBLE TOO.
THE MAIN PROBLEM RIGHT NOW SEEMS TO BE THE LACK OF A GOOD TRIGGER
THIS AFTERNOON. THE BOUNDARY LAYER FLOW IS A UNIFORM SOUTHEAST AND
LITTLE CONVERGENCE IS SEEN IN THE AREA. THUS...ANY BOUNDARY THAT
DOES PRESENT ITSELF COULD TRIGGER INITIATION AS THERE WILL BE NO
CAP IN PLACE. WITH SUCH VIGOROUS CONVECTION IN KS/OK...UPSTREAM OF
THE AREA...WE COULD SEE A CONVECTIVE VORTICITY MAX APPEAR IN THE
FLOW AND POSSIBLY BECOME AN INITIATOR. THE HRRR AND HI RES NMM SEEM
TO BE HINTING AT THIS SOLUTION LATER AFTERNOON.
THIS EVENING...AS STRONG ENERGY ROTATES NORTHEAST...CURRENTLY IN
WEST TX...THE LOW-LEVEL JET IN THE 19.00Z NAM EXCITES AND A NICE
CONVERGENT LOW-LEVEL JET DEVELOPS CONVECTION OVER IOWA AND MOVES
IT NORTHWARD. THE 19.00Z GFS DOES NOT AGREE ON THIS WITH ITS FOCUS
NORTH AGAIN ON THE NWRN WI-CENTRAL MN BOUNDARY. BUT THE HI RES 00Z
RUNS...USING THE NAM AS INITIALIZATION AND BOUNDARY
CONDITIONS...BRING WIDESPREAD CONVECTION IN FROM IA. THERE IS
BETTER JET DYNAMICS AND TRANSPORT IN THE NAM..AND THIS SEEMS
REASONABLE...THUS..HAVE CONTINUED TO HIT THE EVENING
HARD...EVOLVING THE WEATHER NORTH BY MORNING. THE 19.00Z GEM AND ECMWF
AGREE WELL WITH THIS SCENARIO. SO...LOOKING FOR A WET OVERNIGHT.
THERE IS STILL INSTABILITY OVERNIGHT...2K MUCAPE...AND A BIT
BETTER SHEAR.
BOTTOM LINE IS THAT THE DAYTIME HOURS MAY BE PRETTY CLEAN BECAUSE
OF LACK OF A THUNDERSTORM TRIGGER. IF AN MCV FROM OK/KS CAN
DEVELOP TSRA AND THE TSRA CAN ROOT ITSELF IN THE BOUNDARY LAYER
OVER IA...OR SOME BOUNDARY EXISTS...CHANCES INCREASE FOR AFTERNOON
SEVERE WEATHER...AS THE AIR MASS WILL BE WEAKLY CAPPED. THIS
EVENING SEEMS TO PROMOTE INCREASING RAIN AND THUNDERSTORMS WITH
STILL SOME SEVERE POTENTIAL UNTIL THE CAPE IS USED UP...BUT NOT
QUITE AS WIDESPREAD AS AN AFTERNOON EVENT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 318 AM CDT SUN MAY 19 2013
AS THE LOW DRAWS CLOSER MONDAY...SHEAR INCREASES TO SUPERCELL
STRENGTH...BUT AGAIN IT MAY BE DIFFICULT TO IDENTIFY A TRIGGER
WITH LITTLE SURFACE BOUNDARY ACTION IN THE AREA. THE STATIONARY
BOUNDARY REMAINS TO THE NW WITH THE BEST CONVERGENCE. HOWEVER...WITH
THE SURFACE LOW EXPECTED TO BE NEAR KFSD...AND AMPLE MLCAPE AGAIN
NEAR 2000 J/KG...STORMS LOOK TO FORM TO THE WEST AND MOVE INTO THE
AREA TUESDAY EVENING. HOWEVER...THIS PATTERN IS SO UNCAPPED AND
UNSTABLE...WE FOUND IT HARD TO GET DETAILED ON TIMING ANYWHERE.
MONDAY STILL HAS THE POTENTIAL FOR SEVERE WEATHER...AND IT LOOKS
LIKE THE EVENING HOURS. WITH INCREASED WIND SHEAR...ROTATING
STORMS ARE POSSIBLE AND THUS LARGE HAIL AND WIND. AN ISOLATED
TORNADO CANNOT BE RULED OUT BUT THE WIND ENVIRONMENT DOESNT LOOK
OVERLY FAVORABLE.
THE LOW CONTINUES TO SHIFT SLOWLY EAST AND PROVIDE RAIN THREATS
THAT ARE DIFFICULT TO TARGET THROUGH THURSDAY. SOME DRIER AIR BEGINS TO
SHIFT INTO THE AREA ON SOUTHWEST FLOW OFF THE ROCKIES ON
TUESDAY...AND SOMEWHAT COOLER AIR. THIS WILL END THE SEVERE
WEATHER THREAT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1245 AM CDT SUN MAY 19 2013
CONFIDENCE IS INCREASING THAT WEATHER WILL BE AROUND THE TAF SITES
IN THE MORNING HOURS AROUND 12Z. EXACTLY HOW THAT WILL AFFECT THE
AIRFIELDS IS STILL OF LOWER CONFIDENCE. WITH INCREASING
INSTABILITY MOVING IN AND SOME WEAK LIFT...THE CURRENT TSRA OVER
WRN IA WILL SHIFT INTO THE AREA AND WEAKEN AS IT MOVES TOWARD KLSE.
THUS...KRST HAS A BETTER CHANCE OF SEEING TSRA AT THE AIRFIELD
THAN KLSE.
THIS WILL BE A QUICK PERIOD OF WEATHER AND THEN A BREAK IS GOING
TO OCCUR UNTIL PROBABLY THE LATER AFTERNOON HOWEVER...THE TIMING
AND EXTENT OF THE WEATHER THIS AFTERNOON IS STILL VERY MUCH A
CHANGING FORECAST. IT APPEARS THE EVENING WILL BE OF GREATER
COVERAGE OF TSRA AND SHRA BUT THIS COULD BEGIN IN THE AFTERNOON.
PLENTY OF INSTABILITY IS IN PLACE....HIGHEST OF THE SEASON...BUT
THE EXACT TRIGGER FOR TSRA DEVELOPMENT IS IN QUESTION. SEVERE
WEATHER IS POSSIBLE WITH THE INSTABILITY IN PLACE AND LIFT
INCREASING THIS EVENING.
&&
.HYDROLOGY...
ISSUED AT 318 AM CDT SUN MAY 19 2013
HYDROLOGY...THE PROBABILITIES HAVE TIPPED TOWARD A FLASH FLOOD WATCH
FOR 3 PM TOPDAY THROUGH MONDAY. THERE ARE TOO MANY VARIABLES IN
PLAY THAT SUGGEST HEAVY RAINFALL AND FLOODING POTENTIAL INCLUDING
SOIL MOISTURE CENTERED OVER SERN MN ABNORMALLY HIGH...FRIDAYS
RAINFALL HAVING HIGHER END FLOODING OUTCOMES IN SERN
MN...PRECIPITABLE WATER VALUES OVER 150 PERCENT NORMAL MOVING
IN...SBCAPE BUILDING DURING THE DAY TO NEAR 3K /ML NEAR 1800/
BASED ON 67F DEW POINT...AND FORCING INCREASING DURING THE EVENING WITH
STRONGER MOISTURE TRANSPORT CONVERGENCE AND SHEAR MOVING INTO THE
AREA.
THIS FLASH FLOOD WATCH MAY BE EXPANDED AND POSSIBLY EXTENDED INTO
MONDAY NIGHT SHOULD DETAILS SUGGEST THE FLOODING THREAT COULD
REMAIN. THERE IS SOME SUGGESTION THAT THE VERY HIGH PRECIPITABLE
WATER MOIST CONVEYOR BELT WOULD SHIFT INTO WI AS A DRIER ROCKIES AIR
MASS ADVECTS IN ON SWRLY FLOW.
RIVERS IN THE WATCH AREA WOULD ALSO SEE RAPID RISES ASIDE FROM THE
FLASH FLOODING EFFECTS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH FROM 3 PM CDT THIS AFTERNOON THROUGH MONDAY
EVENING FOR MNZ079-086-087-094-095.
IA...FLASH FLOOD WATCH FROM 3 PM CDT THIS AFTERNOON THROUGH MONDAY
EVENING FOR IAZ008.
&&&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...BAUMGARDT
HYDROLOGY...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1245 AM CDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 724 PM CDT SAT MAY 18 2013
HAVE BEEN WORKING TO GET A BETTER HANDLE ON THE THUNDERSTORM
CHANCES AROUND DAYBREAK MOVING IN FROM THE SOUTHWEST. THE
THUNDERSTORM CHANCES ARE CLOSELY TIED TO THE SHORTWAVE TROUGH
SHIFTING OUT OF KS/OK AND THE FOCUS OF CURRENT DEEP CONVECTION
THERE. THE STORMS/SHRAS WOULD BE ON THE LEADING EDGE OF A MOISTURE
SURGE OF 12G/KG MIXING RATIO ABOVE THE SURFACE ON THE 305K SURFACE
/850MB/...THUS CAPE WILL INCREASE TOO...PER 18.23Z RAP. SHOULD SEE
THE LINE OF CONVECTION ADVECT ACROSS IA ON THE NOSE OF THIS
MOISTURE AND LOW-LEVEL JET CONVERGENCE. HOWEVER...THE BEST
LOW-LEVEL JET CONVERGENCE IS FURTHER INTO IA AND IS WEAKER IN THE
LOCAL AREA PER THE RAP. PROBABLY WHY THE RAP HAS THE AREA DRY.
THE SPC SSEO HAS A PROBABILITY OF 70+ PERCENT CHANCE OF 40DBZ OR
HIGHER FROM THE 7 CONVECTION ALLOWING MODELS BY 12Z ALONG I-35.
THIS IS PROBABILITY IS DECREASING HOWEVER. 3 OF THE LATEST 4 HRRR
RUNS ALSO HAVE A TSRA/SHRA ALONG I-35 BY 09Z IN MN-IA. THE LATEST
RUN 18.21Z BRINGS THIS CONVECTIVE SYSTEM TO JUST WEST OF THE MISS
RIVER BY 12Z SUN. THERE ARE CONVECTIVE ELEMENTS OVER 50 DBZ WITH
ABOUT 1200 J/KG OF MUCAPE WHICH IS ELEVATED. THE WIND SHEAR IS
FAIRLY WEAK WITH ONLY 20-30 KTS OF FLOW AT 6 KM.
HAVE UPDATED THE FORECAST TO INCLUDE A HIGHER CHANCE OF TSRA WEST
OF THE MISS RIVER SUNDAY AROUND DAYBREAK. THE FORCING IS WEAKER
THAN FURTHER TO THE SOUTHWEST /IA/...BUT THIS MOISTURE SURGE
ISENTROPICALLY LIFTING IN THE OVERNIGHT HOURS USUALLY PRODUCES
SOME ELEVATED STORMS. WILL CONTINUE TO MONITOR...RAIN CHANCES MAY
NEED TO BE INCREASED FURTHER. WITH LIMITED WIND SHEAR...WOULD
THINK POSSIBLY AN ISOLATED SEVERE HAILER MAY BE ABOUT ALL THAT COULD
OCCUR. THE RAINFALL SHOULD BE PROGRESSIVE...BUT ANY RAIN ON THE
SERN MN AREA HAS TO BE FOLLOWED CLOSELY...SOILS JUST CANNOT TAKE
IT. A FLASH FLOOD WATCH MAY BE NEEDED THERE. SEE FACEBOOK POST FOR
30 DAY WATER EQUIVALENT THAT HAS FALLEN THERE...5-8 INCHES ABOVE
NORMAL.
&&
.SHORT TERM...(TONIGHT AND SUNDAY)
ISSUED AT 250 PM CDT SUN MAY 18 2013
MORNING MCS QUICKLY DIED OUT FOR THE AFTERNOON...WHILE A SFC
WARM FRONT HANGS ACROSS CENTRAL MN INTO NORTHERN WI. THE 850 MB JET
KICKS IN ACROSS SOUTHERN/CENTRAL PLAINS...AND EXPECT SOME CONVECTION
TO INITIATE. STEERING WINDS WOULD FAVOR A NORTH/NORTHEAST
MOVEMENT...LIKELY KEEPING IT JUST WEST OF THE FORECAST AREA THROUGH
12Z. THAT SAID...MESO ARW/HRRR SUGGEST IT COULD WORK INTO NORTHEAST
IA/SOUTHEAST MN BY 12Z. THINK THE POSITIONING OF THE VARIOUS WEATHER
ELEMENTS GIVES THIS SOLUTION SOME MERIT...AND WILL TREND SOME POPS
TOWARD THIS. ELSEWHERE...SOME INSTABILITY A LOFT PER BUFKIT
SOUNDINGS...BUT WITHOUT A KICKER TO TAP INTO IT...SHOULD BE A DRY
NIGHT.
FOR SUNDAY...UPPER LEVEL TROUGH HANGS WELL WEST WHILE ITS SFC LOW
WOBBLES OVER THE PLAIN STATES. THE SFC WARM FRONT STAYS NORTH WITH
THE COLD FRONT SOUTH OF THE SFC LOW...BUT SOME HINTS THAT ANOTHER
SFC BOUNDARY COULD EXTEND FROM THE LOW ACROSS EASTERN IOWA. THE LOW
LEVEL JET AND MOISTURE TRANSPORT FOCUS INTO EASTERN IA/EASTERN
MN/WESTERN WI BY 00Z MONDAY...PERSISTING THROUGH THE EVENING HOURS.
GFS/NAM SFC TDS PUSH UPPER 60S TO LOW 70S INTO THE FORECAST AREA BY
00Z MON...WHICH IS PROBABLY OVERDONE...ESP THE GFS. MID 60S SEEM
MORE REASONABLE...SO ASSOCIATED MODELED SBCAPE VALUES WILL ALSO BE
LESS AS A RESULT. MLCAPES AROUND 1200 J/KG LOOK GOOD. 0-6 KM SHEAR
IS NOT THAT IMPRESSIVE...MOSTLY 30 KTS. LOW LEVEL SHEAR IS MUCH
BETTER...30+ KTS IN THE 0-3 KM LAYER...WITH 15-25 KTS OF 0-1KM SHEAR
FROM 00-06Z SUNDAY EVENING. THE ATMOSPHERE WOULD BE SUPPORTIVE OF
SEVERE WEATHER...WITH A BETTER CHANCE FOR SUPERCELL DEVELOPMENT
SOUTHWEST...WHICH COULD MIGRATE INTO THE FORECAST AREA.
OVERALL...THINK THE THREATS WOULD FOCUS ON LARGE HAIL...DAMAGING
WINDS...AND FLASH FLOODING. CAN/T RULE OUT AN ISOLATED TORNADO WITH
THE STRONG NEAR SFC SHEAR AND POTENTIAL FOR ANY SMALLER SFC BOUNDARY
PROVIDING ENHANCED VORTICITY.
TIMING...LOCATION...AND INITIATION ARE ALL RATHER NEBULOUS
THOUGH...AND CONFIDENCE IS LOW IN THE WHERES AND WHENS OF THE
CONVECTION. IT IS HIGHER THAT THE BEST PCPN CHANCES WILL BE SUNDAY
NIGHT...WITH THE MAIN SEVERE THREAT IN THE EVENING.
SCENARIO COULD PLAY OUT LIKE THIS...MCSS OVER THE PLAINS TONIGHT
MAKE THEIR WAY TOWARD THE FORECAST AREA SUNDAY MORNING. THEY MAY OR
MAY NOT BRING RAIN TO WESTERN PORTIONS OF THE AREA...BUT WILL AT
LEAST BRING SOME CLOUDS FOR THE EARLY PART OF THE DAY. ATMOSPHERE
WILL NEED SOME TIME TO CLEAR/THIN CLOUDS...SO INSTABILITY WILL BE
BUILD LATER IN THE DAY. THIS WILL THEN INTERACT WITH SFC BOUNDARY
HANGING SOUTHEAST FROM THE SFC LOW AND AN UPPER LEVEL SHORTWAVE
TROUGH ROTATING OUT OF THE MEAN TROUGH TO SPARK SHOWERS/STORMS OVER
IOWA. SUPERCELL DEVELOPMENT IS PROBABLE...WITH SHEAR SUGGESTING A
TRANSITION TO LINE/BOWING SEGMENTS AS THE STORMS MOVE INTO THE
AREA...DAMAGING WINDS POSSIBLE AS THE STORMS ORIENT TO THE 0-3KM
SHEAR VECTOR. AGAIN THOUGH...CAN/T RULE OUT ISOLATED TORNADOES AS
LOW LEVEL SHEAR AND VARIOUS/POSSIBLE SFC BOUNDARIES WOULD SUPPORT
THIS. OF COURSE...THESE SEVERE THREATS ARE CONDITIONAL ON HOW
QUICKLY THE ATMOSPHERE CAN RELOAD...AND WHERE THE VARIOUS BOUNDARIES
WILL LIE.
FORECAST NEEDS MORE CLARITY...WHICH HOPEFULLY COMES WHEN WE GET A
BETTER HANDLE ON WHAT THE OVERNIGHT CONVECTION WILL DO.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 250 PM CDT SAT MAY 18 2013
A WET START TO THE WORK WEEK AS THE UPPER LEVEL LOW WOBBLES VERY
SLOWLY EASTWARD...WITH VARIOUS BITS OF ENERGY ROTATING AROUND IT.
THE SFC LOW TAKE AN EASTWARD TRACK ACROSS NORTHERN IA. PERSISTENT
INFLUX OF LOW LEVEL MOISTURE AHEAD OF AND WRAPPED AROUND THE LOW.
THIS MIX WILL KEEP THE AREA UNDER PERIODS OF SHOWERS AND
THUNDERSTORM.
WITH INSTABILTY RE-ESTABLISHING ITSELF MONDAY
AFTERNOON/EVENING...AND DECENT WIND SHEAR...ANOTHER SHOT FOR SEVERE
WEATHER WILL BE POSSIBLE. MUCH WILL DEPEND ON WHERE VARIOUS MESO
FEATURES RESIDE...ALA SURFACES BOUNDARIES...AND WHERE THE GREATER
INSTABILITY BUILDS.
SOME HOPE THAT THE SLOW MOVING SYSTEM FINALLY EXITS EAST THU NIGHT
WITH THE EC MERGING THE UPPER LEVEL LOW WITH A DEEPER/STRONGER LOW
OVER THE NEW ENGLAND STATES. THE GFS...HOWEVER...LINGERS THE LOW
LONGER...AND WOULD FIRE A FEW MORE SHOWERS/STORMS AROUND THE LOW/SFC
BOUNDARY THU NIGHT INTO EARLY FRI. HIGH PRESSURE TAKES OVER FOR
FRI/FRI NIGHT...PROMISING A DRY PERIOD. THAT SAID...THE EC IS
ALREADY BRINGING IN SOME QPF TO THE WEST SAT WITH WARM AIR
ADVECTION/SHORTWAVE INTERACTION ON THE BACKSIDE OF THE HIGH.
NOT MUCH CONFIDENCE WITH WHEN THE LOW WILL FINALLY EXIT EAST...AND
MODEL DIFFERENCES AREN/T HELPING WITH THE CLARITY. WILL HOLD WITH
THE CONSENSUS SOLUTION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1245 AM CDT SUN MAY 19 2013
CONFIDENCE IS INCREASING THAT WEATHER WILL BE AROUND THE TAF SITES
IN THE MORNING HOURS AROUND 12Z. EXACTLY HOW THAT WILL AFFECT THE
AIRFIELDS IS STILL OF LOWER CONFIDENCE. WITH INCREASING
INSTABILITY MOVING IN AND SOME WEAK LIFT...THE CURRENT TSRA OVER
WRN IA WILL SHIFT INTO THE AREA AND WEAKEN AS IT MOVES TOWARD KLSE.
THUS...KRST HAS A BETTER CHANCE OF SEEING TSRA AT THE AIRFIELD
THAN KLSE.
THIS WILL BE A QUICK PERIOD OF WEATHER AND THEN A BREAK IS GOING
TO OCCUR UNTIL PROBABLY THE LATER AFTERNOON HOWEVER...THE TIMING
AND EXTENT OF THE WEATHER THIS AFTERNOON IS STILL VERY MUCH A
CHANGING FORECAST. IT APPEARS THE EVENING WILL BE OF GREATER
COVERAGE OF TSRA AND SHRA BUT THIS COULD BEGIN IN THE AFTERNOON.
PLENTY OF INSTABILITY IS IN PLACE....HIGHEST OF THE SEASON...BUT
THE EXACT TRIGGER FOR TSRA DEVELOPMENT IS IN QUESTION. SEVERE
WEATHER IS POSSIBLE WITH THE INSTABILITY IN PLACE AND LIFT
INCREASING THIS EVENING.
&&
.HYDROLOGY...SUNDAY AND INTO NEXT WEEK
ISSUED AT 250 PM CDT SAT MAY 18 2013
WITH CONSIDERABLE RAINFALL ACROSS PORTIONS OF SOUTHEAST MN AND
NORTHEAST IA YESTERDAY...SOILS ARE MOIST. 1 HR FFG IS FROM 1 1/2 TO
2 INCHES TO NEAR 2 INCHES FOR 3 HOURS. WHILE TODAY BROUGHT A PERIOD
OF DRYING...SHOWERS AND THUNDERSTORMS RETURN FOR SUNDAY INTO
WEDNESDAY. THERE IS THE POTENTIAL FOR 1 TO 3 INCHES OVER THIS
PERIOD. IF THIS FALLS IN A SHORT PERIOD...LOCALIZED FLASH FLOODING
WOULD OCCUR. A FLASH FLOOD WATCH MAY BE NECESSARY FOR PORTIONS OF
THE AREA. STREAMS...CREEKS...AND RIVERS HAVE RESPONDED TO THE RECENT
RAINFALL...MOSTLY WITHIN BANK RISES. HOWEVER...REPEATED ROUNDS OF
HEAVY RAIN COULD PUSH SOME OF THE MORE FLASHY BASINS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA TO NEAR FLOOD STAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
UPDATE...BAUMGARDT
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...BAUMGARDT
HYDROLOGY....RIECK
AREA FORECAST DISCUSSION
NWS ALBANY NY
425 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS. THE HUMID AND UNSETTLED WEATHER CONTINUES TOMORROW AND
THURSDAY WITH MORE CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A
COLD FRONT RETURNS DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE
HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 424 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM
SECTOR...WITH A VERY SLOW MOVING BOUNDARY SITUATED ACROSS THE
NORTHERN PORTION OF OUR AREA.
MOVING ALONG THIS SFC BOUNDARY AND AIDED BY A STRONG SW LOW LEVEL
JET...A BROKEN LINE OF CONVECTION CONTINUES TO MOVE ACROSS THE
ADIRONDACKS AND MOHAWK VALLEY. THIS LINE HAS WEAKENED FROM EARLIER
IN THE OVERNIGHT HOURS WHEN IT PRODUCED WIND DAMAGE AND HAIL
ACROSS CNY AND THE LAKE ONTARIO REGION. STILL...A QUICK DOWNPOUR
AND SOME GUSTY WINDS WILL SWEEP FROM WEST TO EAST FROM THE
SOUTHEASTERN ADKS AND CENTRAL MOHAWK VALLEY INTO THE LAKE GEORGE
SARATOGA REGION FOR THE NEXT FEW HOURS THROUGH SUNRISE. MOST AREAS
FROM THE CAPITAL REGION ON SOUTH WILL STAY DRY. BY SHORTLY AFTER
SUNRISE...THIS BATCH OF CONVECTION SHOULD BE DONE AND MOST AREAS
ACROSS THE CWA WILL BE DRY.
HOWEVER...ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING
THE HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS OR
STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE TO THE W-SW.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. SPC HAS PLACED OUR REGION IN A
/SEE TEXT/ AREA FOR TODAY...AND WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
MOSTLY CLEAR SKY ACROSS THE REGION EARLY THIS MORNING...WITH A WEAK
WARM FRONT ACROSS NORTHERN NY. SOME FOG HAS FORMED AT KPSF AND
ACKNOWLEDGING IFR FOG TEMPORARILY MVFR THROUGH ABOUT 14Z AT KPSF. A
BAND OF SHOWERS AND THUNDERSTORMS OVER LAKE ONTARIO IS MOVING
EAST...AND THE SOUTHERN EDGE OF THE CONVECTION IS NEAR KSYR. THERE
IS A GUST FRONT AHEAD OF THE CONVECTION THAT IS MOVING AT AROUND 35
KT...BUT BASED ON THE STEERING FLOW SEEN ON RADARS ACROSS THE
REGION...THIS CONVECTION SHOULD MAINLY TRACK DUE EAST.
AREA 00Z SOUNDINGS ALSO SHOW ENOUGH INSTABILITY ACROSS THE REGION TO
SUSTAIN THE CONVECTION AS IT TRACKS THROUGH EASTERN NY AND INTO
WESTERN NEW ENGLAND. HOWEVER...IT IS TIMED TO REACH THE HUDSON
VALLEY AROUND 09Z...AND WITH CONTINUED STABILIZING OF THE ATMOSPHERE
THROUGH THE EARLY MORNING HOURS...AND WEAKENING OF THE
CONVECTION...JUST INDICATING VCSH AT KGFL...KALB AND KPSF...ALTHOUGH
THE BEST CHANCE OF A SHOWER OR THUNDERSTORM WOULD BE KGFL BASED ON
RADAR TRENDS. WILL AMEND TAFS AN HOUR OR TWO PRIOR TO A SHOWER OR
THUNDERSTORM IF RADAR SUGGESTS STRENGTH OF CONVECTION AND MOVEMENT
CONTINUES.
OUTSIDE OF THESE SHOWERS AND THUNDERSTORMS...SOME PATCHY MVFR FOG
AND SOME SCATTERED VARIABLE BROKEN CLOUDS AROUND 1500 FEET ARE
POSSIBLE THROUGH ABOUT 14Z. ONCE WHATEVER RAIN TRACKS EAST OF THE
REGION...BROKEN CLOUDS ABOVE 3000 FEET TEMPORARILY SCATTERED THROUGH
THE AFTERNOON. SOME SCATTERED SHOWERS OR THUNDERSTORMS COULD
DEVELOP LATE IN THE AFTERNOON AND INTO THE EVENING...BUT NO REAL
ORGANIZED FOCUS SO LEAVING OUT ANY VCSH FOR NOW...BUT MAY BE ADDED
IN LATER TAF ISSUANCES TODAY ONCE THE CHARACTER OF CONVECTION IS
KNOWN WHEN IT FORMS.
WINDS SHOULD BE NEARLY CAL THROUGH ABOUT 14Z. WINDS SHOULD BECOME
LIGHT SOUTH TO SOUTHWEST AT LESS THAN 10 KT LATER THIS MORNING AND
CONTINUE THIS AFTERNOON AND EVENING.
OUTLOOK...
TUE NIGHT...VFR/MVFR. AT KALB AND KGFL -SHRA LIKELY WITH CHC TSRA.
AT KPSF AND KPOU CHC -SHRA/-TSRA.
WED...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -SHRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
402 AM EDT TUE MAY 21 2013
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH THURSDAY. A COLD FRONT
WILL DROP THROUGH THE AREA ON FRIDAY WITH DRY HIGH PRESSURE BUILDING
IN NEXT WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PRE-DAWN...ANOTHER MILD MORNING ACROSS THE REGION AS A MOIST
ATMOSPHERE PERSISTS OVER THE FORECAST AREA. WATER VAPOR SATELLITE
IMAGERY INDICATES A WEAK MID LOW LEVEL LOW PRESSURE NOT FAR FROM
JACKSONVILLE FLORIDA...EMBEDDED IN A 500 MB TROUGH AXIS THAT RUNS
N THROUGH CHARLESTON TO GREENSBORO NC. AREAS OF LAYERED CLOUDS
EARLY THIS MORNING WITH POCKETS OF STRATUS EXPECTED TO DEVELOP
OVER INLAND AREAS. WE MAINTAINED PATCHY FOG MENTIONS IN OUR
FORECAST WHERE SKIES CLEARED OVERNIGHT. WEAK UPPER DIFLUENCE AND
MOIST COASTAL CONVERGENCE NOTED ON LATEST MESOANALYSIS OVER EASTERN
SOUTH CAROLINA AND WE MAINTAINED 20/30 POPS ACROSS THE CHARLESTON
TRI-COUNTY AREA AS DAYBREAK NEARS...ELSEWHERE MAINLY DRY EARLY ON.
TODAY...THE UPPER TROUGH DOES NOT MOVE MUCH AND EMBEDDED FEATURES
TEND TO WEAKEN WITH TIME. THE DEEPEST MOISTURE CONTINUES TO RESIDE
OVER SE SOUTH CAROLINA ALONG AND E OF INTERSTATE 95 INCLUDING THE
CHARLESTON AND CENTRAL SOUTH CAROLINA COASTAL AREAS. THROUGH MIDDAY
CONVECTIVE RAINS WILL BEGIN TO DEVELOP AS THE LAND MASS QUICKLY
WARMS WITH THE STEEP SUN ANGLE THIS TIME OF YEAR. THERE COULD BE A
FEW HEAVY DOWNPOURS ALONG THE COAST N OF BEAUFORT IF RECENT TRENDS
FROM THE RAP MODEL PAN OUT. CONVECTIVE TEMPS ARE PRETTY LOW TODAY
AND WE THINK SCATTERED CONVECTIVE RAINS WILL DEVELOP SOUTH ALONG
THE GEORGIA SEA BREEZE AND PROPAGATE W AND SW THIS AFTERNOON. 00Z
MODELS PROGS DIFFER ON THE AMOUNT OF INSTABILITY THIS AFTERNOON
BUT THE OPERATIONAL 13K RUC SHOWS DECENT POTENTIAL FOR SHORT-LIVED
BUT STRONG UPDRAFT POTENTIAL. OUR THINKING FOR SIGNIFICANT WEATHER
TODAY IS SIMILAR TO YESTERDAY/S REASONING...LOCALIZED DOWNPOURS
MORE LIKELY AND ONLY AN ISOLATED SEVERE WEATHER POTENTIAL AS BEST
MID LEVEL INSTABILITY AND LOW AND MID LEVEL LAPSE RATES LINGER W
OF THE AREA.
A COUPLE OF CHANGES WE MADE TO OUR FORECAST TODAY. WE RAISED POPS
TO 40-50 PERCENT IN THE CHARLESTON QUAD-COUNTY REGION AND RAISING
HIGH TEMPS OVER INLAND SE GEORGIA ZONES FURTHER INTO THE UPPER
80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
INLAND CONVECTIVE RAINS WILL BE ENDING EARLY IN THE EVENING AS
THE SEA BREEZE GETS WELL INLAND AND CONVERGENCE DIMINISHES. NO
CHANGES TO THE FORECAST TONIGHT WITH CLOUDS GRADUALLY THINNING
AND LOWS 65-70 DEGREES. WE MAY NEED TO EVENTUALLY ADD SOME PATCHY
FOG IN AGAIN TONIGHT...DEPENDENT ON TRENDS WITH CLOUD DISSIPATION.
A FAIRLY SIMILAR PATTERN WILL PERSIST WEDNESDAY INTO THURSDAY WITH
BROAD UPPER TROUGHING AND ATLANTIC HIGH PRESSURE. SOUTHERLY
LOW-LEVEL FLOW WILL MAINTAIN A FAIRLY MOIST ATMOSPHERE AND HELP PUSH
A SEABREEZE INLAND EACH DAY. THE UPPER TROUGHING WILL CREATE A
SOMEWHAT MORE FAVORABLE ENVIRONMENT FOR CONVECTION TO DEVELOP...
PRIMARILY DRIVEN BY THE SEABREEZE AND BOUNDARY INTERACTIONS. WE KEPT
POPS IN THE 20-30 PERCENT RANGE BOTH DAYS.
THE MODELS ARE NOW QUITE A BIT FASTER AND IN BETTER AGREEMENT
REGARDING A COLD FRONT PUSHING THROUGH FRIDAY MORNING. WE REMOVED
POPS ON FRIDAY AND SHOW DEWPOINTS DROPPING INTO THE UPPER 50S TO
AROUND 60 DURING THE AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THERE IS GOOD MODEL AGREEMENT THAT DRY CANADIAN HIGH PRESSURE WILL
EXPAND SOUTHEAST INTO THE FORECAST AREA OVER THE WEEKEND THEN SHIFT
OFFSHORE. DEWPOINTS LOOK TO DROP INTO THE LOWER 50S SATURDAY AND
SUNDAY...WHICH COMBINED WITH HIGHS IN THE LOWER 80S WILL RESULT IN
PLEASANT SPRING WEATHER. OVERNIGHT LOWS WILL PROBABLY DROP INTO THE
UPPER 50S IN SPOTS. LOW-LEVEL MOISTURE INCREASES EARLY NEXT WEEK AS
THE SURFACE HIGH SHIFTS OFFSHORE...BUT WE DID NOT SEE ANY STRONG
SYNOPTIC SCALE FEATURES TO WARRANT ADDING PRECIP.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
KCHS...ISOLATED SHOWERS AND BRIEF MVFR CIGS POSSIBLE OVERNIGHT...
OTHERWISE VFR UNTIL DAYBREAK. A RICH TROPICAL-LIKE FEED OF
MOISTURE AND COASTAL CONVERGENCE WILL INTERACT WITH THE SEA BREEZE
DURING THE LATE MORNING AND AFTERNOON HOURS TODAY...PRODUCING
SCATTERED SHRA AND POSSIBLE TSRA. FOR NOW WE MAINTAINED A PROB30
GROUP FOR SHRA AND MVFR CONDITIONS FROM 15-21Z UNTIL TRENDS CAN BE
BETTER DEFINED.
KSAV...WE ANTICIPATE A FEW HOURS OF MVFR CONDITIONS IN LIGHT
LOW STRATUS/STRATOCUMULUS OVERNIGHT AND CONTINUE TO INDICATE THAT
TREND. ISOLATED TO SCATTERED CONVECTION WILL FORM ALONG THE SEA
BREEZE BOUNDARY DURING LATE MORNING THROUGH MID AFTERNOON...THUS
A PROB30 GROUP FROM 16-21Z WAS MAINTAINED.
EXTENDED AVIATION...SPORADIC REDUCTIONS IN CEILINGS/VSBYS MAINLY IN
AFTERNOON/EVENING SHOWERS OR STORMS THROUGH THURSDAY.
&&
.MARINE...
THROUGH TONIGHT...THE STEADY STATE SYNOPTIC PATTERN CONTINUES UNABATED.
OFFSHORE RIDGE OF HIGH PRESSURE EXTENDS W ACROSS THE COASTAL WATERS...
GENERATING SE AND S WINDS LESS THAN 15 KT AND SEAS IN THE 2-4 FOOT
RANGE...HIGHEST OVER OUTER GEORGIA WATERS BEYOND 20 NM.
HIGH PRESSURE WILL SIT OVER THE WESTERN ATLANTIC UNTIL FRIDAY WHEN A
CANADIAN HIGH DROPS SOUTHEAST. WE MAY SEE A BRIEF PERIOD OF SMALL
CRAFT ADVISORY CONDITIONS FRIDAY NIGHT INTO SATURDAY AS THE GRADIENT
TIGHTENS AND COLD ADVECTION MIXES SOME DECENT WINDS TO THE SURFACE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
229 AM EDT TUE MAY 21 2013
.AVIATION...(FOR THE 06Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED
AT 225 AM EDT TUE MAY 21 2013
MADE SOME ADJUSTMENTS TO TAFS TO ACCOMMODATE ACCELERATING LINE OF
STORMS MOVING OUT OF NE IL INTO NW INDIANA. SPC MESO ANALYSIS
SHOWS 3 HOUR SFC BASED CAPES CHANGES 200 TO 800 J/KG LOWER...SO
EXPECT STORMS TO GRADUALLY WEAKEN THE REST OF THE NIGHT. ALSO...
SOME SUPPORT FROM THE RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET
WILL WANE AS THE JET AXIS TRANSLATES BACK TO THE WEST GIVEN THE
RESPONSE TO AN UPSTREAM TROF MOVING INTO THE CENTRAL PLAINS. SO
KEPT THUNDER OUT AFTER 12Z. A FAIRLY TIGHT PRESSURE GRADIENT WILL
PERSIST TODAY...WITH DAYTIME MIXING OF HIGHER MOMENTUM AIR CAUSING
SOUTHWEST GUSTS TO AROUND 25 KNOTS.
&&
.SYNOPSIS...
ISSUED AT 532 PM EDT MON MAY 20 2013
SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE TO INCREASE TONIGHT
THROUGH WEDNESDAY...WITH A FEW SHOWERS POSSIBLY LINGERING INTO
THURSDAY. THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS
EVENING THROUGH TUESDAY NIGHT. DRIER AND COOLER WEATHER IS
ANTICIPATED LATE THIS WEEK INTO NEXT WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
REMNANT GRAVITY WAVE FROM OVERNIGHT CONVECTION AND
ASSOCIATED WITH A ~10F DEGREE DEWPOINT DROP IN ITS WAKE HAS WASHED
OUT AS IT MOVED INTO OUR FORECAST AREA. THIS HAS KEPT MODERATELY
UNSTABLE AIRMASS ACROSS THE EASTERN TWO-THIRDS OF OUR FORECAST AREA.
ADDED SLIGHT CHANCE POPS FOR THE EAST THIS EVENING AS CONVECTION
COULD FIRE ALONG OR IN FRONT OF THIS BOUNDARY WHERE THE AIRMASS IS
CHARACTERIZED BY SBCAPE VALUES IN EXCESS OF 3000 J/KG. THE GREATEST
LIMITING FACTOR IS THE LACK OF SIGNIFICANT FORCING...ALTHOUGH
CONVECTION ACROSS MICHIGAN AND ADDITIONAL CONVECTION FIRING ALONG
THE BOUNDARY ACROSS EASTERN ILLINOIS AT 1830Z INDICATES THIS
BOUNDARY MAY PROVIDE JUST ENOUGH FORCED ASCENT FOR ISOLATED STORM
DEVELOPMENT.
STILL SOME UNCERTAINTY REGARDING CONVECTIVE EVOLUTION AND IMPACTS
ACROSS OUR AREA TONIGHT. DECAYING STORM CLUSTER ACROSS WESTERN
ILLINOIS SHOULD CONTINUE ITS WEAKENING TREND AS IT MOVES INTO A
MOISTURE VOID AREA ACROSS ILLINOIS WITH SURFACE DEWPOINTS IN THE
UPPER 50S. WITH THAT BEING SAID...SOME SHORT TERM MODEL GUIDANCE IS
INDICATING A QUICK RECOVERY OF THE MOISTURE PROFILE IN THAT AREA AS
850 MOISTURE TRANSPORT INCREASES THIS AFTERNOON. IF THE AIRMASS
AHEAD OF THESE STORMS CAN DESTABILIZE OVER THE NEXT FEW HOURS...AS
THE HRRR SUGGESTS...UPSCALE GROWTH OF THAT CLUSTER AS WELL AS
ADDITIONAL STORM DEVELOPMENT MAY TRACK ACROSS THE NORTHWEST PORTION
OF OUR FORECAST AREA DURING THE LATE EVENING. IF STORMS CAN
DEVELOP...SEVERE POTENTIAL DOES EXIST AS 0-6 KM SHEAR OF 35-45 KNOTS
OVERSPREADS THE NORTHWEST PORTION OF OUR FORECAST AREA WITH THE MAIN
THREATS BEING SEVERE HAIL AND WIND.
REMAIN MORE CONFIDENT IN PRECIPITATION CHANCES AFTER 06Z WHEN
REMNANT CONVECTION FROM MISSOURI TRACKS TOWARDS THE AREA. SEVERE
THREAT WILL BE MINIMAL WITH THIS CONVECTION DUE TO ITS TIMING DURING
THE EARLY MORNING HOURS.
TUESDAY LOOKS TO BE COOLER THAN TODAY AS LITTLE SUN WILL BE SEEN
ACROSS OUR FORECAST AREA DUE TO CLOUD DEBRIS FROM FROM OVERNIGHT
CONVECTION AS WELL AS ADDITIONAL DYNAMIC LIFT FROM 40-50 KT LLJ.
SEVERE THREAT DOES EXIST IF A FEW BREAKS IN THE CLOUDS CAN PROVIDE
SIGNIFICANT SURFACE HEATING FOR EVEN MARGINAL SURFACE BASED
INSTABILITY. THE MAIN THREAT WILL BE LARGE HAIL AND DAMAGING WINDS
AS UNIDIRECTIONAL 35-40 KNOT SHEAR OVERSPREADS THE AREA.
&&
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
ONE OR TWO MORE ROUNDS OF CONVECTION TO BEGIN THE FORECAST PERIOD.
MODELS IN PRETTY GOOD AGREEMENT IN SHORT WAVE COMING OUT OF BASE OF
CLOSED LOW AND IMPACTING THE AREA TUE NIGHT. GOOD SUPPORT WILL
ACCOMPANY THIS FEATURE AND 50-60KT MID LEVEL SPEED MAX WILL COMBINE
WITH INFLUX OF LOW LEVEL MOISTURE WITH AT LEAST SUFFICIENT
INSTABILITY TO INITIATE OR MAINTAIN CONVECTION. UNIDIRECTIONAL WIND
PROFILE WITH AROUND 30KT OF SPEED SHEAR WILL HAVE DAMAGING WINDS AS
THE MAIN SEVERE THREAT. CLOSED LOW FINALLY OPENS UP AND WILL MOVE
EASTWARD INTO THE GREAT LAKES REGION WEDNESDAY NIGHT...BRINGING SFC
LOW AND MAIN COLD FRONT WITH IT. MODELS OFFERING VARYING
TIMING/PLACEMENT OF THESE FEATURES BUT ONE MORE ROUND OF CONVECTION
POSSIBLE WEDNESDAY...MAINLY FOR THE EASTERN HALF OF THE CWA. UPPER
TROF AXIS ROTATES THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY
KEEPING CHANCE FOR A FEW SHOWERS BEFORE COOLER DRIER CANADIAN HIGH
PRESSURE BEGINS TO BUILD INTO THE GREAT LAKES REGION ON FRIDAY. THIS
WILL PROVIDE A NICE START TO THE HOLIDAY WEEKEND...QUESTIONS REMAIN
AS TO WHETHER IT WILL LAST THROUGH MONDAY. SFC RIDGE AXIS WILL
PROGRESS EASTWARD SUNDAY AND MONDAY...PLACING OUR AREA ON THE
WESTERN PERIPHERY OF THE HIGH WHILE MEDIUM RANGE MODELS ATTEMPTING
TO BRING SHORT WAVE ENERGY DOWN IN NW FLOW. GETTING BETTER MODEL
AGREEMENT WITH THIS SOLN BUT LOTS OF VARIATION IN TIMING AND
PLACEMENT. ENSEMBLE GUIDANCE NEAR OR MOSTLY BELOW CLIMO FOR POPS AS
WELL SO WILL STILL HOLD OUT FOR DRY FORECAST FOR AT LEAST ONE MORE
ISSUANCE. TEMPS TRENDING SEASONABLY COOLER WITH AOB NORMAL FOR MOST
&&
.UPDATE...
ISSUED AT 857 PM EDT MON MAY 20 2013
DIFFICULT FORECAST WITH RESPECT TO CONVECTIVE PROBABILITIES THROUGH
THE FORECAST PERIOD AND DISMAL EARLY FAILURE. AMID A STRONGLY
DIVERGENT BOUNDARY LAYER AXIS PER VIS SAT IMAGERY LYING ACROSS
NERN IL/NWRN IN PAST FEW HOURS...HAS PROVEN TO BE STRONGLY
DETRIMENTAL. THIS DESPITE MODERATE SURFACE BASED INSTABILITY POOL
SITUATED ACROSS NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN THIS
EVENING. A WELL SCOURED/DEEPLY MIXED ENVIRONMENT EXISTS ACROSS
NORTHERN/CENTRAL ILLINOIS WITH PUTRID MID/UPR 50S DPS THIS
EVENING...REMOVES ANY IMMEDIATE CONCERN FOR INITIATION NEXT FEW
HOURS. THIS IMMEDIATE UPSTREAM ENVIRON WAS WITHIN WAKE OF EARLY
AFTERNOON SHORTWAVE...THAT INITIATED STRONG/SEVERE CONVECTION
MIDDAY ACROSS YOOP/NORTHERN LOWER MICHIGAN. EASTERN FRINGE OF DRY
SLOTTED ENVIRONMENT WITH 7.5-8.25 C/KM MID LEVEL LAPSE RATES TO
LIKELY KEEP UPDRAFTS IN CHECK/ISOLATED REMAINDER OF THE EVENING.
WILL MAINTAIN THAT ANY SIG CHANCE FOR CONVECTION TO BE ASSOCIATED
WITH WELL UPSTREAM CONVECTION PRESENTLY ACROSS EAST CENTRAL
MO...WITH SEVERAL HOUR WAIT UNTIL A MORE VIGORED UPSTREAM 925-8H
WIND FIELD WITH PRESENT FOCUS INTO THE OZARKS/NORTHERN ARKANSAS
SHIFTS NORTHEASTWARD OVERNIGHT INTO SRN/CENTRAL ILLINOIS WHILE
JETLET VEERS/RAMPS TO 45-55KTS...FINALLY NOSING INTO KLAF VCNTY
AROUND 09-12 UTC PER RAP/ARW...AND A SIGNIFICANTLY POOR/LAGGARD
HRRR3KM THAT RECENTLY CAME IN LINE TO REALITY. SUFFICIENT
PREPARATORY CONDITIONING/RECOVERY OF ENVIRONMENT VIA MOISTURE
FLUX CONVERGENCE SFC-900MB ALONG/NORTH OF STRONG ISODROSOTHERMAL
GRADIENT WITH UPPER 60S/NEAR 70 DPS SOURCE TAPPED WITH
TIME....PUSHING NORTH OF I70 TO MAINTAIN MUCAPE POOL OF 1200-2000
J/KG ACROSS FORECAST AREA. THIS SHOULD ALLOW DECENT MAINTENANCE OF
CONVECTIVE COMPLEX WITH ACROSS MISSOURI TO REACH NORTHERN INDIANA
WELL AFTER MIDNIGHT INTO KSBN AND NEAR DAYBREAK AT KFWA.
DISFAVORED TIMING/PARCEL ASCENT BECOMING LESS SURFACE BASED WITH
TIME AND MODEST DEEP LAYER SHEAR TO LARGELY PRECLUDE SEVERE
POTENTIAL...THOUGH HAVE CONTD TO ACK THAT STRONGEST CELLS MAY
APPROACH LOW END SEVERE LIMITS IN HWO.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...STEINWEDEL/KG
AVIATION...SKIPPER
SHORT TERM...BENTLEY
LONG TERM...JAL
UPDATE...MURPHY
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
415 AM EDT TUE MAY 21 2013
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OWB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PREFIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 205 AM EDT TUE MAY 21 2013
MOSTLY CLEAR SKIES AND DEWPOINTS IN THE 60S HAVE ALREADY LED TO FOG
DEVELOPMENT IN THE VALLEYS AND PER OBS THIS MAY BE DENSE IS SOME
LOCATIONS IN THE BIG SANDY/TUG VALLEY REGION ATTM. KI35...K22 AND
KPBX SHOULD EXPERIENCE SOME OF THE LOWER VIS THROUGH 13Z.
HOWEVER...GUIDANCE ONLY TAKES LOZ AND SME DOWN TO MVFR AROUND 9Z.
EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP 16Z AND AFTER...POSSIBLY
SOONER AS SOME MODEL GUIDANCE BRINGS AND OUTFLOW BOUNDARY INTO THE
AREA BEFORE 16Z. WE HAVE CONTINUED WITH SOME VCTS AND CB FOR THIS IN
THE TAFS. WINDS THROUGH THE NIGHT WILL BE LIGHT AND VARIABLE...PICKING
UP FROM THE SOUTHWEST WITH SPEEDS UP TO 10 KTS POSSIBLE AFTER 13Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
THE EXTENDED FORECAST DISCUSSION WILL BE ISSUED SHORTLY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 205 AM EDT TUE MAY 21 2013
MOSTLY CLEAR SKIES AND DEWPOINTS IN THE 60S HAVE ALREADY LED TO FOG
DEVELOPMENT IN THE VALLEYS AND PER OBS THIS MAY BE DENSE IS SOME
LOCATIONS IN THE BIG SANDY/TUG VALLEY REGION ATTM. KI35...K22 AND
KPBX SHOULD EXPERIENCE SOME OF THE LOWER VIS THROUGH 13Z.
HOWEVER...GUIDANCE ONLY TAKES LOZ AND SME DOWN TO MVFR AROUND 9Z.
EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP 16Z AND AFTER...POSSIBLY
SOONER AS SOME MODEL GUIDANCE BRINGS AND OUTFLOW BOUNDARY INTO THE
AREA BEFORE 16Z. WE HAVE CONTINUED WITH SOME VCTS AND CB FOR THIS IN
THE TAFS. WINDS THROUGH THE NIGHT WILL BE LIGHT AND VARIABLE...PICKING
UP FROM THE SOUTHWEST WITH SPEEDS UP TO 10 KTS POSSIBLE AFTER 13Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
342 AM EDT TUE MAY 21 2013
.SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
&&
.LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
&&
.MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.AVIATION...ISSUED 1151 PM EDT MON MAY 20 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS ACROSS ILLINOIS WILL LIFT N-NE DURING
THE EARLY MORNING HOURS. ADDITIONAL CONVECTIVE DEVELOPMENT IS
POSSIBLE OUT AHEAD OF THIS CLUSTER WITHIN A SECONDARY SURGE IN
MOISTURE...TRAVERSING SE MI IN THE 09Z TO 15Z TIME FRAME. THIS WILL
SUPPORT THE INCLUSION OF SOME THUNDERSTORMS IN THE TAFS AROUND
DAYBREAK. THE COVERAGE OF MORNING CONVECTIVE ACTIVITY AND EXTENT OF
CLOUD COVER WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE DAY TUESDAY.
FOR DTW...GIVEN THE EASTWARD EXTENT OF CONVECTION ONGOING ACROSS
ILLINOIS...CHANCES OF SOME THUNDERSTORM ACTIVITY IN AND AROUND METRO
APPEAR HIGH ENOUGH TO ADD THEIR INCLUSION IN THE TAFS DURING THE 11
TO 14Z TIME FRAME. ALTHOUGH TIMING OF ADDITIONAL THUNDERSTORMS LATER
IN THE DAY TUESDAY REMAINS HIGHLY UNCERTAIN...THERE IS THE POTENTIAL
FOR SEVERAL ROUNDS OF THUNDERSTORMS TO IMPACT METRO ON TUESDAY.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS TUESDAY MORNING AND AFTERNOON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
AVIATION.....SC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS BILLINGS MT
357 AM MDT TUE MAY 21 2013
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SHOWERS WILL LINGER OVER THE EAST THIS MORNING AND TAPER OFF
THROUGH THE AFTERNOON. THE PRECIPITATION SHOULD STAY MAINLY EAST
OF KMLS AND IMPACT KBHK. FLYING CONDITIONS ARE EXPECTED TO REMAIN
VFR WITH ONLY ISOLATED MVFR CONDITIONS DEVELOPING IN HEAVIER
SHOWERS. THE REST OF THE AREA WILL HAVE A PARTLY CLOUDY SKY WITH
ONLY ISOLATED SHOWERS AND THUNDERSTORMS NEAREST THE MOUNTAINS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/B 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
358 AM CDT TUE MAY 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1223 AM CDT TUE MAY 21 2013
FOR THE KLBF TERMINAL...EXPECT VFR CIGS OVER THE NEXT 24 HOURS.
SCATTERED CLOUDINESS AON 4000 FT AGL WILL BECOME BROKEN AT 3500 FT
AGL TUESDAY MORNING AND WILL PERSIST THROUGH TUESDAY EVENING.
NORTHWESTERLY WINDS AROUND 12 KTS TONIGHT WILL INCREASE TO 15 TO 30
KTS ON TUESDAY...BEFORE DIMINISHING TO AROUND 10 KTS TUESDAY
EVENING.
FOR THE KVTN TERMINAL...MVFR CIGS OF 1500 TO 2000 FT AGL ARE
EXPECTED TO DEVELOP OVERNIGHT AND PERSIST THROUGH TUESDAY EVENING.
CIGS ARE EXPECTED TO LIFT TO 3000 FT AGL LATE TUESDAY EVENING.
NORTHWESTERLY WINDS OF 15 TO 30 KTS WILL PERSIST INTO THE OVERNIGHT
AND WILL CONTINUE THROUGH MID EVENING TUESDAY. WINDS WILL DIMINISH
TO AROUND 12 KTS BY LATE TUESDAY EVENING. SCATTERED RAIN SHOWERS ARE
POSSIBLE TUESDAY AFTERNOON IN NORTHERN NEBRASKA. GIVEN SCATTERED
COVERAGE...WILL HANDLE MENTION WITH A PROB30 GROUP.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
104 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A SOUTHWESTERLY FLOW OF WARM AND MORE HUMID AIR WILL CONTINUE ACROSS
THE REGION FOR MUCH OF THIS WEEK...WHILE A FRONTAL BOUNDARY ALSO
STALLS OUT ACROSS NEW YORK STATE AND SETS THE STAGE FOR INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS. THE MORE UNSETTLED CONDITIONS
WILL LAST THROUGH THURSDAY...BEFORE A COLD FRONT CROSSES THE AREA
AND USHERS IN COOLER AND DRIER WEATHER FOR THE END OF THE WEEK AND
THE MEMORIAL DAY WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
BAND OF SHOWERS AND THUNDERSTORMS IS HOLDING TOGETHER ACROSS
SOUTHERN ONTARIO AND NOW WORKING TOWARD THE NIAGARA FRONTIER SO
HAVE INCREASED POPS FROM BUFFALO NORTH AND EASTWARD THIS EVENING
FOLLOWING ALONG THE LINES OF A MIX OF LATEST HRRR RUNS AND RADAR
EXTRAPOLATION. TIMING CONTINUES TO PLACE THUNDERSTORMS INTO THE
NIAGARA FRONTIER AROUND MIDNIGHT THEN SHIFTING THEM EASTWARD THROUGH
THE EARLY MORNING. 00Z BUF RAOB SHOWS AREA OF ELEVATED INSTABILITY
OVER 1000 J/KG ABOVE 700MB WHICH THE CURRENT STORMS CAN FEED OFF OF.
KBUF RADAR VELOCITY SHOWING NO WINDS HIGHER THAN 30 KNOTS AND WITH
LOW LEVEL INVERSION NOT EXPECTING ANY SEVERE IMPACTS FROM
CONVECTION. OTHERWISE BEFOREHAND THERE IS A SLIGHT CHANCE OF A POP
UP SHOWER AHEAD OF THE MAIN LINE AS THE HRRR SUGGESTS BUT KEEP
FORECAST GRIDS IN LINE WITH MAIN BAND OF PRECIP WHERE HIGHEST
CONFIDENCE LIES. TEMPS WILL REMAIN WARM AND HUMID. 850MB TEMPS IN
THE MID TEENS AND A RETURN OF BLANKETING CLOUD COVER WILL KEEP
OVERNIGHT LOW TEMPS UP IN THE LOWER TO MID 60S ACROSS THE ENTIRE
FORECAST AREA.
THE UPPER RIDGE AXIS WILL BE OVER OR TO THE EAST OF THE FORECAST
AREA ON TUESDAY AND WILL ALLOW AN INFLUX OF WARMTH AND MOISTURE WITH
DEWPOINTS SURGING TO THE UPPER 60S ACROSS WESTERN NY DURING TUESDAY
AFTERNOON. THE SUPPRESSIVE SUBSIDENCE WILL BE NEARLY ABSENT ON
TUESDAY SO CAN EXPECT CONVECTION TO DEVELOP DURING THE AFTERNOON
ALONG THE LAKE BREEZE BOUNDARIES AND THE INLAND TERRAIN. LAKE COOLED
AIR WILL PROVIDE LAKE SHADOWS WITHIN ABOUT HALF A COUNTY`S WIDTH OF
THE LAKE ERIE AND ONTARIO SHORES. WILL HAVE POPS INCREASING TO THE
LIKELY CATEGORY BY THE END OF THE DAY ON TUESDAY WITH THE CONTINUED
INFLUX OF HIGH THETA-E AIR. HIGH TEMPS ON TUESDAY SHOULD BE IN THE
LOWER TO MID 80S FOR MOST AREAS...LOWER TO MID 70S EXPECTED ACROSS
THE CLOUDIER AND POSSIBLY RAINIER TUG HILL PLATEAU AND EASTERN LAKE
ONTARIO COUNTIES.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
SUMMERY CONDITIONS WILL CONTINUE ACROSS OUR REGION ON WEDNESDAY...
AS A DEEP SOUTHERLY FLOW WILL REMAIN IN PLACE IN ADVANCE OF A
BROAD SFC LOW FOUND OVER LOWER MICHIGAN. WHILE IT WILL BE WARM AND
HUMID WITH TEMPERATURES RESEMBLING THOSE OF JULY...THERE WILL BE
SOME UNSETTLED WEATHER TO DEAL WITH AS WELL. OUR UNSTABLE AIRMASS
WILL CERTAINLY SUPPORT SOME SHOWERS AND THUNDERSTORMS...ALTHOUGH
THE BULK OF THE DAY MAY END UP BEING RAINFREE. LETS LOOK AT THE
PROS AND CONS TO THIS CONVECTION.
WORKING AGAINST WIDESPREAD CONVECTION WILL BE A SHORTWAVE RIDGE THAT
WILL LIFT UP ACROSS OUR REGION. THIS COULD BE A DOUBLE EDGED SWORD
THOUGH...AS THE RIDGE COULD HELP TO THIN SOME OF THE EXPECTED CLOUD
COVER. THAT WOULD LEAD TO GREATER DIURNALLY INDUCED INSTABILITY THAN
IS BEING FORECAST...WHICH IN TURN WOULD LIKELY LEAD TO MORE
AFTERNOON CONVECTION. ON THE OTHER HAND...THE SUBSIDENCE FROM THE
PASSING RIDGE IN TANDEM WITH MOSTLY CLOUDY SKIES COULD MINIMIZE THE
THREAT OF STORMS (AS WAS ALSO EXPRESSED IN A PREVIOUS STORM
PREDICTION CENTER DISCUSSION)...OR AT LEAST HOLD THEM OFF UNTIL MID
TO LATE AFTERNOON.
EITHER WAY YOU SLICE IT...THERE SHOULD BE AT LEAST 500-1000 J/KG OF
SBCAPE BY WEDNESDAY AFTERNOON SO THERE SHOULD BE SHOWERS OR
THUNDERSTORMS TO DEAL WITH AS WE MOVE THROUGH THE DAY. THIS ACTIVITY
WILL LIKELY FOCUS ON TWO AREAS. THE FIRST BEING A NEARLY STALLED
FRONTAL BOUNDARY THAT WILL BE FOUND FROM THE NORTH SHORE OF LAKE
ONTARIO TO THE NORTH COUNTRY...AND THE SECOND BEING A LAKE BREEZE
BOUNDARY THAT SHOULD PUSH EAST OF LK ERIE. THE LATTER WOULD BE OF
MORE CONCERN BECAUSE THIS WOULD BE THE TRIGGER TO RELEASE THE
GREATER INSTABILITY OVER THE WRN COUNTIES. THIS LEADS US TO THE
POTENTIAL FOR SEVERE WEATHER.
LETS STATE RIGHT UP FRONT THAT SPC HAS OUR FORECAST AREA OUTLINED IN
A SLIGHT RISK FOR SEVERE STORMS ON WEDNESDAY. THAT BEING SAID AND
AS WAS THE CASE IN YESTERDAYS MORNING DISCUSSION...AM NOT OVERLY
IMPRESSED WITH THE OVERALL SET UP FOR SEVERE WEATHER. WE COULD HAVE
SUPPRESSED INSTABILITY FROM CLOUD COVER AND ONGOING SHOWER
ACTIVITY...BUT I AM JUST AS UNIMPRESSED WITH 0-3KM BULK SHEAR
(GENERALLY <25 M/S) AND LACKLUSTER MID LEVE LAPSE RATES OF 6 DEG
C/KM. ONE HAS TO LOOK AT A DEEPER LAYER (0-6 KM) TO FIND IMPRESSIVE
BULK SHEAR VALUES OF 35-40 M/S. A TELLING SIGN WILL LIKELY BE HOW
MUCH SUN WE GET DURING THE MORNING AND MIDDAY. THE MAIN THREAT FROM
ANY STRONG TO SEVERE STORMS WOULD BE STRAIGHT LINE WINDS...AND IF WE
CAN GET OUR CAPES UP OVER 1500 J/KG...SOME LARGE HAIL. PWAT VALUES
>1.5 INCHES WILL ALSO LIKELY LEAD TO SOME TORRENTIAL DOWNPOURS...
BUT THERE SHOULD BE ENOUGH WINDS TO MOVE THE STORMS ALONG AND
MINIMIZE THE POTENTIAL FOR HYDRO ISSUES. BOILING THIS ALL DOWN...
WILL MAINTAIN HIGH LIKELY TO CAT POPS BUT WILL REFRAIN FROM ADDING
ANY ENHANCED TSRA WORDING. WILL DEFER THIS TO LATER SHIFTS FOR
FURTHER REVIEW.
ON WEDNESDAY NIGHT...THE AFOREMENTIONED SFC LOW WILL TRACK BY TO OUR
NORTH WHILE THE CONVECTION FROM THE EVENING HOURS WILL GRADUALLY
SUBSIDE WITH THE LOSS OF DAYTIME HEATING AND SUBSEQUENT
STABILIZATION OF THE LOWEST LEVELS. THIS WILL LEAVE A WARM AND DAMP
NIGHT WITH NOCTURNAL TEMPERATURES ONCE AGAIN NOT FALLING OUT OF THE
60S.
THE VARIOUS GUIDANCE PACKAGES THEN START TO DIVERGE ON THE HANDLING
OF THE WAVY FRONTAL BOUNDARY THAT WILL OOZE ACROSS OUR FORECAST AREA
ON THURSDAY. IN PREVIOUS MODEL RUNS...THE ECMWF HAS BEEN THE FASTER
PACKAGE IN BRINGING THE FRONT THROUGH. IT NOW TRAILS THE GFS...AND
FOR WHAT ITS WORTH...THE NAM. THE SECONDARY WAVE ALONG THE TRAILING
FRONT IS WHAT IS OBVIOUSLY THROWING A MONKEY WRENCH INTO THE
MODELS...BUT IN ANY CASE...THE MODELS ARE IN GENERAL AGREEMENT THAT
THERE WILL BE A WEALTH OF LOW LEVEL MOISTURE THAT WILL BE LIFTED IN
FAIRLY WIDESPREAD SHOWERS. JUST DO NOT SEE ENOUGH INSTABILITY TO
HOLD ONTO THE SLGT CHC THAT WE HAVE FOR THUNDER...AS LAPSE RATES ARE
GENERALLY BELOW 6 DEG C/KM BY MID MORNING. WILL COMPROMISE AND LEAVE
THE MENTION FOR THE MORNING ONLY. OTHERWISE...IT WILL BE A WET AND
NOTICEABLY COOLER DAY WITH TEMPERATURES AVERAGING SOME 10 DEG F
LOWER THAN PREVIOUS DAYS. HIGHS SHOULD GENERALLY BE IN THE UPPER 60S
TO LOWER 70S.
WHILE THE WAVY FRONT WILL BE WELL TO OUR EAST THURSDAY NIGHT...THE
SUPPORTING H5 TROUGH WILL BE JUST CROSSING THE LOWER LAKES. THIS
SHOULD KEEP SOME LEFTOVER SHOWERS OVER THE REGION...ESPECIALLY
DURING THE FIRST HALF OF THE NIGHT. MEANWHILE...TEMPERATURES ARE
EXPECTED TO TUMBLE INTO THE 40S...WHICH WILL BE QUITE REFRESHING
AFTER SEVERAL DAYS OF MID JULY-LIKE WEATHER.
FRIDAY WILL FEATURE SEASONABLY COOL CONDITIONS AS H85 TEMPS IN THE
VCNTY OF 4C WILL ONLY SUPPORT AFTERNOON HIGHS AROUND 60 F. WHAT IS
MUCH LESS CERTAIN IS WHETHER ALL OF THE SHOWER ACTIVITY WILL BE
DONE. THE 00Z GFS IS NOW BEING STUBBORN WITH CLEARING OUT THE
SHOWERS AND LEFTOVER CLOUDS...SO WILL HAVE TO KEEP AT LEAST SLGT CHC
POPS OVER THE REGION DURING THE MORNING AND INCREASE OUR CLOUD COVER
A BIT. WILL STILL LEAN MORE ON THE ECMWF SOLUTION THOUGYH...WHICH AT
THIS POINT FAVORS A MORE OPTIMISTIC SCENARIO.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
PLENTY OF SUNSHINE AND SEASONABLY COOL TEMPERATURES WILL BE THE NAME
OF THE GAME THIS WEEKEND AS HIGH PRESSURE WILL SETTLE ACROSS THE
GREAT LAKES. 850MB TEMPS DROPPING TO AROUND 0C SHOULD ONLY YIELD
HIGHS TOPPING OUT IN THE LOWER 60S FOR MOST AREAS ON SATURDAY...
NEARLY 10 DEGREES BELOW NORMAL. LIKEWISE OVERNIGHT LOWS WILL RUN ON
THE CHILLY SIDE WITH READINGS IN THE LOWER 40S ALONG THE LAKE PLAINS
WHILE AREAS FARTHER INLAND ACROSS THE SOUTHERN TIER AND NORTH
COUNTRY COULD DROP INTO MID 30S...POTENTIALLY SETTING THE STAGE FOR
A FROST...PARTICULARLY SATURDAY NIGHT WHEN THE SURFACE HIGH IS
FORECAST TO BE OVERHEAD.
A GRADUAL REBOUND IN TEMPERATURES IS EXPECTED FOR THE LATTER HALF OF
THE WEEKEND AS THE COLDEST AIR ASSOCIATED WITH THE UPPER LEVEL
TROUGH DEPARTS THE REGION AND WARMER AIR BEGINS TO CREEP NORTH FROM
THE OHIO VALLEY ONCE AGAIN. OTHERWISE...EXPECT DRY WEATHER TO
CONTINUE THROUGH THE END OF THE WEEKEND.
&&
.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
EXPECT VFR CONDITIONS TO BRIEFLY DETERIORATE WITHIN TS AROUND
MIDNIGHT FOR KBUF/KIAG AND CLOSER TO 05Z/06Z FOR KROC AND 07Z/08Z
FOR KART. LEFT KJHW OUT OF TS BECAUSE SOUTHERN FLANK OF STORMS WILL
REMAIN TO THE NORTH OF THE AIRFIELD. SOME MVFR STRATUS IS POSSIBLE
HERE THOUGH SIMILAR TO WHAT HAPPENED LAST NIGHT.
THE UPPER AND MID LEVEL RIDGE AXES TO PASS ACROSS THE REGION AND TO
THE EAST ON TUESDAY. WILL HAVE A SLIGHTLY BETTER CHANCE OF AFTERNOON
AND EVENING CONVECTION...ALONG THE LAKE BREEZE BOUNDARIES AND OVER
THE INTERIOR OF THE FORECAST AREA.
OUTLOOK...
TUESDAY THROUGH THURSDAY...NUMEROUS SHOWERS AND THUNDERSTORMS WITH
ASSOCIATED BRIEF MVFR/IFR...OTHERWISE VFR.
FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.
SATURDAY...VFR.
&&
.MARINE...
A LINE OF SHOWERS AND THUNDERSTORMS MOVING ACROSS EASTERN MICHIGAN
AND LAKE HURON WILL SHIFT EAST THIS EVENING AND MAY PUSH ACROSS THE
LAKES ARRIVING NEAR MIDNIGHT AND SHIFTING EAST THROUGH THE EARLY
MORNING HOURS.
OTHERWISE...FOR MUCH OF THIS WEEK WINDS WILL REMAIN RELATIVELY LIGHT
AND VARIABLE IN DIRECTION DUE TO A NEARLY STATIONARY FRONTAL
BOUNDARY THAT WILL REMAIN DRAPED ACROSS THE REGION...AS WELL AS THE
DAILY DEVELOPMENT OF LAKE BREEZES. AS A RESULT...WAVE HEIGHTS SHOULD
ALSO REMAIN MINIMAL. OTHERWISE...SHOWER AND THUNDERSTORM
CHANCES WILL INCREASE MARKEDLY FOR THE TUESDAY THROUGH THURSDAY TIME
FRAME. A COLD FRONTAL PASSAGE WILL TURN WINDS TO A NORTHERLY
DIRECTION WITH AN INCREASE IN WAVE HEIGHTS... ESPECIALLY ALONG THE
SOUTH SHORE OF LAKE ONTARIO ON FRIDAY MORNING.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JJR
NEAR TERM...SMITH/WCH
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...SMITH
MARINE...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
322 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH...AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER
WEATHER WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN
THIS RECENT WET PERIOD SEVERAL DAYS AGO HAS DEGENERATED INTO A
500-TO-700 MB SHEAR AXIS. WIND SPEEDS SURROUNDING THE UPPER FEATURE
ARE TOO WEAK AT THIS POINT TO SUPPORT DYNAMIC LIFT...BUT RICH LOW
AND MID LEVEL MOISTURE REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS
WITH PRECIPITABLE WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY
CONVECTIVE CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY
STEEPER THAN THE MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S
SEABREEZE BOUNDARY SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED
SHOWERS AND THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION
(NEARLY 10000 FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE
PROCESSES WILL DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS
THIS AFTERNOON SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM
THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...PLENTIFUL LOW-LEVEL MOISTURE HAS LED TO DEVELOPMENT OF
IFR STRATUS CEILINGS INLAND WHICH MAY CONTINUE THROUGH DAYBREAK. THE
ONLY POTENTIAL TO SCOUR OUT THESE LOW CIGS EARLIER WILL BE IF
CONVECTIVE SHOWERS OR T-STORMS CAN DEVELOP ACROSS THE SC PEE DEE
REGION AS SHOWN ON THE LATEST SEVERAL RUNS OF THE HRRR MODEL. THIS
COULD LEAD TO ENOUGH DISTURBANCE OF THE STABLE LOW-LEVEL INVERSION
TO LIFT CEILINGS AT KFLO TEMPORARILY INTO THE VFR RANGE SHORTLY
BEFORE DAYBREAK. ALONG THE COAST VFR CONDITIONS SHOULD PREVAIL
THROUGH DAYBREAK WITH THE POSSIBLE EXCEPTION OF SCATTERED SHOWERS
ADVECTING ONSHORE OFF THE ATLANTIC OCEAN...MAINLY AFTER 09Z...WITH
ACCOMPANYING MVFR CIGS.
AFTER DAYBREAK A TYPICAL SUMMER AIRMASS WILL YIELD SCATTERED SHOWERS
AND THUNDERSTORMS DURING THE HEAT OF THE DAY. PREVAILING SOUTH WINDS
SHOULD SWEEP MOST OF THE ACTIVITY AWAY FROM THE COAST BY
MID-AFTERNOON WITH FLO/LBT SEEING THE BEST POTENTIAL OF VSBY
RESTRICTIONS IN SHOWERS OR STORMS.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE
OVERALL SYNOPTIC WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH
PRESSURE HAS DROPPED SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE
NORTHERN PLAINS IS STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS
WILL ENSURE A SOUTH WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH
TONIGHT. SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE
MOST NUMEROUS THIS MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE
CLEARING OUT MOST OF THIS ACTIVITY FROM THE COASTAL WATERS THIS
AFTERNOON. SEAS CURRENTLY RANGE FROM 3-4 FT ON BUOYS IN THE CAPE
FEAR VICINITY...IN A COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6
SECOND SOUTHERLY WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...TRA
MARINE...TRA/JDW
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A TROUGH OVER THE REGION WILL GRADUALLY WEAKEN THROUGH WEDNESDAY. A
STRONG COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST LATE
THURSDAY... THEN PUSH THROUGH TO THE COAST BY FRIDAY MORNING. COOL
HIGH PRESSURE WILL FOLLOW THE FRONT LATE FRIDAY INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 315 AM TUESDAY...
DELAYED A BIT WITH DISCUSSION TO SEE THE LATEST EC MODEL SINCE
MODELS WERE AT ODDS ON TIMING/LOCATION OF CONVECTION CHANCES TODAY.
WATER VAPOR SATELLITE DATA INDICATED THE WEAKENING MID/UPPER TROUGH
STILL LINGERING OVER THE REGION. PRECIPITABLE WATER VALUES REMAIN
VERY HIGH (GENERALLY 1.5 TO 1.75 INCHES). AT THE SURFACE... A WEAK
TROUGH WAS LOCATED OVER THE EASTERN PIEDMONT WITH DEW POINT VALUES
IN THE UPPER 60S TO NEAR 70. ONLY SCATTERED SHOWERS WERE NOTED OVER
THE COASTAL PLAIN AT 06Z/21 MAY.
THE LATEST HI-RES MODELS... IN PARTICULAR THE HRRR (WHICH PREFORMED
WELL WITH THE CONVECTION ON MONDAY)... BUT INCLUDING THE NMM EAST
AND ARW EAST INDICATE SOME DEVELOPMENT OF CONVECTION WESTWARD
BETWEEN 09Z AND 12Z OVER THE SOUTHERN PIEDMONT AND SANDHILLS
REGION.... SPREADING NE ACROSS THE FAYETTEVILLE AND RALEIGH AREAS
AROUND RUSH HOUR THIS MORNING. INTERESTINGLY ENOUGH... THESE HI-RES
MODELS ALSO INDICATE THE TROUGH AND ASSOCIATED CONVECTION SETTLING
SOUTH INTO THE LOWER COASTAL PLAIN BY THIS AFTERNOON. THIS IS IN
STARK CONTRAST TO THE OPERATIONAL NAM/GFS WHICH BOTH DEPICT AN
UPTICK IN CONVECTION WITH AFTERNOON HEATING... AND LITTLE THIS
MORNING.
IN ADDITION... THE HI-RES MODELS ALSO SHOW THE CURRENT LINE OF
STORMS OVER WESTERN KY/TN SURGING TOWARD THE APPALACHIANS LATER
TODAY... THEN POSSIBLY CROSSING THE MOUNTAINS INTO THE PIEDMONT
BETWEEN 00Z-06Z/WED (TONIGHT).
NEEDLESS TO SAY... CONVECTION LOCATION AND TIMING IS DIFFICULT AT
BEST TO FORECAST BEYOND 6 HOURS... THEREFORE WE WILL USE THE LATEST
SATELLITE/RADAR TRENDS... ALONG WITH CURRENT DATA TO TRY TO PIN DOWN
THE FAVORED TIMING/LOCATION OF CONVECTION TODAY AND TONIGHT.
FOR NOW... SINCE THE HRRR PREFORMED WELL MONDAY WITH THIS TROUGH
OVERHEAD... WE WILL LEAN TOWARD SCATTERED CONVECTION THIS MORNING...
WITH ADDITIONAL SCATTERED CONVECTION MAINLY SOUTH AND EAST THIS
AFTERNOON. MORE ISOLATED STORMS EXPECTED TO THE NORTH AND WEST.
HIGHS WILL RETURN TO NORMAL WITH ADDITIONAL HEATING TODAY... LOWER
TO MID 80S.
TONIGHT... AT LEAST SOME CHANCE OF A LINE OF STORMS COMING OUT OF
THE BLUE RIDGE APPROACHING OR AROUND SUNSET. THE AIR MASS SHOULD
BECOME MORE UNSTABLE ESPECIALLY OVER THE WESTERN PIEDMONT DURING
THIS TIME. HOWEVER... MLCAPES OF LESS THAN 1500 J/KG SHOULD YIELD
SUB SEVERE CONVECTION ALONG AND EAST OF THE BLUE RIDGE TODAY OR
TONIGHT. LOW END CHANCE OF SHOWERS/STORMS INTO THE MIDNIGHT HOUR IN
THE WEST... OTHERWISE PARTLY CLOUDY. LOWS IN THE MID TO UPPER 60S.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 310 AM TUESDAY...
WEAK SHORTWAVE RIDGING OVER THE REGION WILL YIELD MOSTLY DRY AND
WARM WEATHER FOR ONE DAY (WED). HOWEVER...SUFFICIENT MOISTURE WILL
STILL BE IN PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR
1.5 INCHES OR SO. WIDELY SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS CAN BE EXPECTED. HIGHS SHOULD BE IN THE MID/UPPER
80S... WITH OVERNIGHT LOWS IN THE MID/UPPER 60S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...
UPPER LEVEL TROUGH WILL MOVE EASTWARD FROM THE MIDWEST ON
THURSDAY...WHICH WILL PUT THE AREA IN DEEP SOUTH TO SOUTHWESTERLY
FLOW DURING THE DAY. WITH MOISTURE IN PLACE AND SUFFICIENT
INSTABILITY... WITH MLCAPE VALUES OF 500 TO 1000 J/KG...
THUNDERSTORMS WILL DEVELOP DURING THE DAY. BULK SHEAR VALUES NEAR 25
KTS WILL SUPPORT THE DEVELOPMENT OF SOME MULTICELL CLUSTERS... AND
FEW STRONGER STORMS WITH GUSTY WINDS ARE POSSIBLE. NO WIDESPREAD
SEVERE WEATHER IS EXPECTED... AS THE BEST UPPER LEVEL FORCING
REMAINS NORTH OF THE AREA. HIGHS IN THE LOW TO MID 80S... LOWS IN
THE MID 60S.
THE ASSOCIATED COLD FRONT WILL PROGRESS INTO WESTERN NORTH CAROLINA
THURSDAY EVENING... REACHING THE COAST BY ABOUT 12Z FRIDAY. MIDLEVEL
DRYING WILL SPREAD ACROSS THE AREA FRIDAY... ENDING PRECIPITATION
AND DECREASING CLOUD COVER THROUGH THE DAY FROM WEST TO EAST. COLD
ADVECTION WILL TEMPER HIGHS... WHICH WILL BE IN THE MID 70S TO LOW
80S. COOLER LOWS IN THE MID 50S.
THE TROUGH MOVES OFF THE COAST EARLY SATURDAY... WITH AN UPPER LEVEL
RIDGE ACROSS THE MIDDLE OF THE COUNTRY AND THE SURFACE HIGH
POSITIONED WEST OF THE AREA... PUTTING THE REGION IN A NORTHWEST
FLOW REGIME THROUGH THE WEEKEND... AND KEEPING TEMPERATURES
SEVERAL DEGREES BELOW NORMAL THROUGH MONDAY... WITH HIGHS IN THE
UPPER 70S TO NEAR 80.. AND LOWS IN THE MID TO UPPER 50S.
&&
.AVIATION /00Z TUESDAY THROUGH FRIDAY/...
AS OF 140 AM TUESDAY...
24 HOUR TAF PERIOD:
LIFR TO IFR CIGS AND MVFR VSBYS EXPECTED THROUGH 13Z-15Z TODAY...
THEN VFR CONDITIONS THIS AFTERNOON. ISOLATED TO SCATTERED
THUNDERSTORMS POSSIBLE THIS AFTERNOON. MVFR TO IFR CIGS AND VSBYS
MAY REDEVELOP LATER TONIGHT 09Z-12Z... FOLLOWED BY VFR CONDITIONS
WEDNESDAY.
LONG TERM:
AREAS OF STRATUS (LIFR TO IFR CIGS) AND VSBYS ARE EXPECTED AGAIN
THURSDAY MORNING. OTHERWISE... MOSTLY VFR CONDITIONS THU-FRI WITH A
CHANCE OF SHOWERS AND THUNDERSTORMS WITH MVFR CIGS/VSBYS BOTH DAYS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...PWB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
140 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A TROUGH OVER THE REGION WILL GRADUALLY WEAKEN THROUGH WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 PM MONDAY...
THROUGH TONIGHT: THE MAJORITY OF THE SHOWERS HAVE DISSIPATED OR
MOVED OUT OF THE AREA THIS EVENING. A FEW ISOLATED SHOWERS HAVE
DEVELOPED DURING THE PAST COUPLE HOURS...BUT HAVE NOT BEEN HEAVY OR
LONG LASTING. THE 00Z UPPER AIR ANALYSES SHOW THE WAVE OVER CENTRAL
NC FROM 850-500 MB...WITH A SHORTWAVE TROUGH TO THE SOUTHWEST AT 250
MB. AS A PAIR OF VORTICITY MAXIMA EMBEDDED IN THE MID LEVEL TROUGH
PIVOTS OVER EASTERN NC OVERNIGHT...ADDITIONAL SHOWERS COULD DEVELOP
ACROSS THE SOUTHEAST. THE 00Z SOUNDING AT KGSO STILL YIELDS MLCAPE
AROUND 1000-1500 J/KG WITH A MOIST BOUNDARY LAYER AND RELATIVELY
DRIER AIR IN THE MID LEVELS. THE LATEST HRRR SHOWS ADDITIONAL SHOWER
ACTIVITY DEVELOPING ACROSS THE SOUTHEAST AROUND MIDNIGHT AS A MID
LEVEL DISTURBANCE MOVES OVER THE AREA. HAVE INCREASED RAIN CHANCES
IN THE EAST OVERNIGHT TO REFLECT THE POTENTIAL DEVELOPMENT.
TEMPERATURES ACROSS THE AREA ARE IN THE UPPER 60S TO LOW 70S...WITH
OVERNIGHT LOWS IN THE MID 60S EXPECTED.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...
TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.
MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.
TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 240 PM MONDAY...
FOR WEDNESDAY...WEAK SHORTWAVE RIDGING WILL BUILD OVER THE AREA...
WHILE AT THE SURFACE...THE BERMUDA HIGH WILL RIDGE WESTWARD INTO THE
CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN EVEN FURTHER DECREASE IN
PRECIP COVERAGE. HOWEVER...SUFFICIENT MOISTURE WILL STILL BE IN
PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR 1.5 INCHES OR
SO. THEREFORE...AM STILL EXPECTING TO SEE WIDELY SCATTERED TO
SCATTERED DIURNALLY DRIVEN CONVECTION...WITH THE HIGHEST CHANCES
BEING ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HIGHS ONCE
AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS IN THE
MID/UPPER 60S.
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WORK WEEK AS THE MID/UPPER LEVEL RIDGE SHIFTS
OFFSHORE AHEAD OF OUR NEXT MID/UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT. MODELS REMAIN IN GENERAL AGREEMENT WITH BRINGING THE
FRONT THROUGH THE FORECAST AREA LATE THURSDAY NIGHT/EARLY FRIDAY.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. BULK SHEAR VALUES WILL INCREASE TO
AROUND 25 KNOTS OR SO...THEREFORE BETTER STORM ORGANIZATION IS
EXPECTED...HOWEVER THE BEST UPPER LEVEL FORCING WILL PASS WELL TO
OUR NORTH. THEREFORE...EVEN THOUGH AN ISOLATED SEVERE STORM CANNOT
BE COMPLETELY RULED OUT...THE OVERALL THREAT REMAINS LOW AT THIS
TIME. WITH THE INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND
FRIDAY...TEMPS WILL MOSTLY BE IN THE LOW/MID 80S.
IT STILL APPEARS THE WEEKEND AND INTO EARLY NEXT WEEK WILL BE DRY AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT. SLIGHTLY COOLER
TEMPS ARE EXPECTED DURING THIS TIME FRAME...GENERALLY THE UPPER 70S
TO LOWER 80S...WITH OVERNIGHT LOWS IN THE 50S.
&&
.AVIATION /00Z TUESDAY THROUGH FRIDAY/...
AS OF 140 AM TUESDAY...
24 HOUR TAF PERIOD:
LIFR TO IFR CIGS AND MVFR VSBYS EXPECTED THROUGH 13Z-15Z TODAY...
THEN VFR CONDITIONS THIS AFTERNOON. ISOLATED TO SCATTERED
THUNDERSTORMS POSSIBLE THIS AFTERNOON. MVFR TO IFR CIGS AND VSBYS
MAY REDEVELOP LATER TONIGHT 09Z-12Z... FOLLOWED BY VFR CONDITIONS
WEDNESDAY.
LONG TERM:
AREAS OF STRATUS (LIFR TO IFR CIGS) AND VSBYS ARE EXPECTED AGAIN
THURSDAY MORNING. OTHERWISE... MOSTLY VFR CONDITIONS THU-FRI WITH A
CHANCE OF SHOWERS AND THUNDERSTORMS WITH MVFR CIGS/VSBYS BOTH DAYS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...KC
SHORT TERM...ELLIS
LONG TERM...KRR
AVIATION...PWB
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
132 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A DISTURBANCE ALOFT MOVING ACROSS THE AREA WILL MAINTAIN SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER IS EXPECTED
MID WEEK. A COLD FRONT IS EXPECTED TO APPROACH AND CROSS THE REGION
ON FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER INTO THE NEXT
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 130 AM TUESDAY...LATEST SEVERAL HRRR RUNS SHOW INCREASING
POTENTIAL FOR NOCTURNAL CONVECTION LATE TONIGHT...PARTICULARLY IN
THE SC PEE DEE REGION FROM FLORENCE WESTWARD...AND ALSO ACROSS
COASTAL SE NORTH CAROLINA. THAT IS ESSENTIALLY THE ONLY CHANGE TO
THE FORECAST. PREVIOUS DISCUSSION FROM 1100 PM FOLLOWS...
CONVECTIVE ACTIVITY HAS WANED ACROSS THE FA THIS EVENING...NEARLY
IDENTICAL TO WHAT TRANSPIRED SUNDAY EVENING. THE ATM ACROSS THE FA
HAS BEEN ONCE AGAIN TAXED AND BECOME SOMEWHAT STABLE...AND WILL NEED
SOME TIME TO DE-STABILIZE. LIKE LAST EVENING AND OVERNIGHT...THE
DAYS INSOLATION WILL NOT BE AVAILABLE TO AID THIS DESTABILIZATION
PROCESS. WILL HAVE TO RELY...AGAIN LIKE LAST NIGHT...DYNAMICS FROM
WEAK PVA ALOFT AND IN ADDITION...THE SLIGHTLY COLDER TEMPS ALOFT TO
REACH THE FA FROM THE SW-W DIRECTION. LATEST CHS 00Z RAOB INDICATES
SUB -10 C AT 500MB. PWS ACROSS THE FA REMAIN IN THE 1.5 TO 1.7
INCHES...VIA LATEST 00Z RAOB DATA FROM MHX AND CHS. FORECAST STORM
MOTIONS REMAIN SLOW...10 KT OR LESS...WHICH HAS RESULTED IN
SUFFIXING THE CONVECTION WITH HEAVY RAIN POSSIBLE. THE COASTAL
PORTIONS OF THE ILM CWA WILL HAVE THE HIGHEST POPS
ILLUSTRATED...MAINLY OCCURRING DURING THE PRE-DAWN HRS INTO DAYLIGHT
TUESDAY. MIN TEMP FORECAST TWEAKED ACROSS THE FA BUT WILL REMAIN IN
THE MID TO UPPER 60S RANGE PREVIOUSLY FORECAST.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...FORECAST MODELS ARE CONSISTENT IN SHOWING
THE MID LEVEL PATTERN TRANSITIONING FROM WHAT SEEMS LIKE A NEVER
ENDING TROUGH/WEAKNESS TO MORE OF A SOUTHWESTERLY FLOW. THIS IN
RESPONSE TO THE MASSIVE MID LEVEL LOW FINALLY OPENING UP ACROSS
THE NORTHERN PLAINS AND GETTING KICKED OUT.
AT THE SURFACE...BERMUDA HIGH PRESSURE WILL REMAIN THE MAIN PLAYER
ALTHOUGH THIS HAS LITTLE IMPACT OR CHANGE ON PREVAILING CONDITIONS
AS THIS HAS BEEN SECONDARY THE PAST FEW DAYS. POPS REMAIN ON A
DIURNAL CYCLE ALTHOUGH LOWER THROUGH THE PERIOD AS THE MID LEVEL
CATALYST IS ALL BUT REMOVED. HAVE OPTED FOR THE WARMER MAV NUMBERS
FOR TEMPERATURES THROUGH THE PERIOD.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 PM MONDAY...ONE LAST DAY OF WARM AND HUMID CONDITIONS ON
THURSDAY AS UPPER TROUGH AND SURFACE COLD FRONT BEAR DOWN ON THE
REGION FROM THE NW. SOMEWHAT SURPRISINGLY MODELS ARE GRAVITATING
TOWARDS A QUICKER SOLUTION AND THE FRONT MAY PUSH THROUGH TUESDAY
NIGHT. AHEAD OF IT SW FLOW AND HEIGHT FALLS SHOULD YIELD BETTER THAN
AVERAGE COVERAGE OF CONVECTION AND WITH A LARGELY PINNED SEABREEZE
THERE MAY BE NO PREFERRED LOCATION FOR MEASURABLE RAINFALL ESP THIS
FAR OUT IN TIME. SYSTEM WILL MOVE A LITTLE BIT SLOWLY OWING TO THE
STRENGTH OF THE DOWNSTREAM RIDGING AND RAIN CHANCES MAY LINGER INTO
FRIDAY ESPECIALLY ALONG THE COAST. MODEST COOLING AND STRONG DRYING
WILL THEN FOLLOW FOR THE WEEKEND AND SOME VERY COMFORTABLE AND
PLEASANT WEATHER APPEARS TO BE ON TAP. DAYTIME DEVIATIONS FROM CLIMO
TEMPS SHOULD BE RATHER SMALL BUT THE NIGHTS MAY TURN COOLISH DUE TO
THE DRYING. THE POST-FRONTAL HIGH MAY MOVE OFF THE COAST ON MONDAY
ALLOWING FOR AN UPTICK IN THE DEWPOINTS.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...PLENTIFUL LOW-LEVEL MOISTURE HAS LED TO DEVELOPMENT OF
IFR STRATUS CEILINGS INLAND WHICH MAY CONTINUE THROUGH DAYBREAK. THE
ONLY POTENTIAL TO SCOUR OUT THESE LOW CIGS EARLIER WILL BE IF
CONVECTIVE SHOWERS OR T-STORMS CAN DEVELOP ACROSS THE SC PEE DEE
REGION AS SHOWN ON THE LATEST SEVERAL RUNS OF THE HRRR MODEL. THIS
COULD LEAD TO ENOUGH DISTURBANCE OF THE STABLE LOW-LEVEL INVERSION
TO LIFT CEILINGS AT KFLO TEMPORARILY INTO THE VFR RANGE SHORTLY
BEFORE DAYBREAK. ALONG THE COAST VFR CONDITIONS SHOULD PREVAIL
THROUGH DAYBREAK WITH THE POSSIBLE EXCEPTION OF SCATTERED SHOWERS
ADVECTING ONSHORE OFF THE ATLANTIC OCEAN...MAINLY AFTER 09Z...WITH
ACCOMPANYING MVFR CIGS.
AFTER DAYBREAK A TYPICAL SUMMER AIRMASS WILL YIELD SCATTERED SHOWERS
AND THUNDERSTORMS DURING THE HEAT OF THE DAY. PREVAILING SOUTH WINDS
SHOULD SWEEP MOST OF THE ACTIVITY AWAY FROM THE COAST BY
MID-AFTERNOON WITH FLO/LBT SEEING THE BEST POTENTIAL OF VSBY
RESTRICTIONS IN SHOWERS OR STORMS.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 130 AM TUESDAY...NO SIGNIFICANT CHANGES TO THE FORECAST NEEDED
EARLY THIS MORNING. PREVIOUS DISCUSSION FROM 1100 PM FOLLOWS...
SSE-SSW WINDS TO REMAIN 10 TO OCCASIONALLY 15 KT OVERNIGHT. THIS IN
RESPONSE TO RIDGING FROM THE WESTERN ATLANTIC HIGH. SOUTH OF THE SFC
RIDGING...AN ESE-SSE FLOW EXTENDS FROM WELL OFFSHORE AND ACROSS A
DECENT FETCH LEADING UP TO THE SE U.S. COAST. THIS HAS RESULTED IN
AN EVOLVING AND BUILDING SE GROUND SWELL AT 2 TO 4 FT EXHIBITING 7
TO 8 SECOND PERIODS...JUST PRIOR TO ENTERING THE ILM COASTAL WATERS.
SEE LATEST 41013 BUOY DATA. COMBINED WITH 3 TO 5 SECOND PERIOD
LOCALLY PRODUCED WIND DRIVEN WAVES...SIGNIFICANT SEAS ACROSS THE
COASTAL WATERS WILL RUN A SOLID 3 TO 4 FT...WITH 5 FOOTERS POSSIBLE
ACROSS THE OUTER WATERS OFF CAPE FEAR. OVERALL...THE WIND AND
SIGNIFICANT SEAS FORECAST REMAINS ON TRACK. ONLY UPDATE WAS TO
RESTRUCTURE POPS ACROSS THE COASTAL WATERS TO ACCOUNT FOR THE
DIMINISHED CONVECTION THIS EVENING...FOLLOWED BY AN INCREASING
COVERAGE TOWARD DAYBREAK TUE.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...BERMUDA HIGH PRESSURE REMAINS THE MAIN FEATURE
FOR THE COASTAL WATERS WITH A SOUTHERLY FLOW EXPECTED TO CONTINUE
THROUGH THE PERIOD. SPEEDS WILL CONTINUE IN A 10-15 KNOT RANGE
WITH A SLIGHT INCREASE CLOSER TO THE COAST EACH LATE MORNING AND
AFTERNOON WITH THE SEA BREEZE. THE LATEST RUN OF SWAN REMAINS
CONSISTENT WITH 2-4 FOOT SEAS.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 300 PM MONDAY...COAST WILL LIE BETWEEN STRONG HIGH PRESSURE
ACROSS THE WEST-CENTRAL ATLANTIC AND APPROACHING COLD FRONT TO THE
NW. THE LATTER WILL BE DISPLACED EASTWARD OF THE MORE TYPICAL
BERMUDA HIGH POSITION WHICH WILL ACT TO EASE THE GRADIENT OTHERWISE
EXPECTED GIVEN SUCH A LARGE ANTICYCLONE. THE RESULTING SWELL ENERGY
COULD BRING SOME SCEC-WORTHY 5 FT SEAS TO PART OF THE AREA MAINLY
NORTHERN ZONES. COLD FRONT NOW APPEARS FASTER THAN PREVIOUSLY
THOUGHT AND SHOULD YIELD VEERING WINDS BY FRIDAY MORNING WITH A TURN
TO OFFSHORE. THE OFFSHORE FETCH AND SWELL DISRUPTION WILL LEAD TO
LOWER SEAS ON FRIDAY BUT THEN THE ENSUING PUSH OF DRY HIGH PRESSURE
COULD TIGHTEN THE GRADIENT AGAIN TO WHERE HEADLINES TOUGH TO RULE
OUT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...DCH/TRA
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...SGL/TRA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
109 AM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 109 AM CDT TUE MAY 21 2013
MAIN UPDATE EARLY THIS MORNING WAS TO TRIM THE WESTERN EDGE OF THE
WIND ADVISORY WITH WINDS DECREASING ALONG TO WEST OF HIGHWAY 83.
OTHERWISE THE INHERITED FORECAST LOOKS GOOD WITH RAIN CONTINUING
MOST AREAS.
UPDATE ISSUED AT 1008 PM CDT MON MAY 20 2013
MAIN UPDATE THIS EVENING WAS TO ADJUST THE WIND ADVISORY. WINDS
ARE DIMINISHING QUICKLY IN THE NORTHWEST AND EXPECT WINDS
SOUTHWEST TO DROP SOON. THEREFORE WILL CANCEL THE ADVISORY IN THE
WEST. WILL KEEP IT GOING IN THE CENTRAL THROUGH 1 AM CDT. DID
EXTEND THE ADVISORY OVER EASTERN PORTIONS OF CENTRAL NORTH DAKOTA
THROUGH 7 AM BASED MAINLY ON RAP ANALYSIS KEEPING 40-45 KNOT WINDS
AT 925MB INTO THE EARLY MORNING HOURS.
UPDATE ISSUED AT 734 PM CDT MON MAY 20 2013
QUICK UPDATE JUST TO FRESHEN UP GRIDS NOT UPDATED WITH THE
EXPANSION OF THE WIND ADVISORY. NO CHANGES TO THE ADVISORY AT THIS
TIME. WITH NEXT UPDATE MAY NEED TO LOOK INTO EXTENDING EASTERN
COUNTIES THROUGH THE NIGHT. MADE SOME MINOR ADJUSTMENTS TO POPS
THROUGH THE EVENING.
UPDATE ISSUED AT 540 PM CDT MON MAY 20 2013
UPDATE LATE THIS AFTERNOON DUE TO STRONG WINDS. WILL EXTEND THE
WIND ADVISORY FARTHER SOUTH TO INCLUDE AREAS ALONG AND NORTH OF
INTERSTATE 94.
VERY STRONG WINDS ACROSS FAR NORTH CENTRAL NORTH DAKOTA LATE THIS
AFTERNOON WITH WIND GUST TO 48KTS RECORDED AT ROLLA. CURRENT GUSTS
HAVE SUBSIDED BACK TO AROUND 40-42 KNOTS. WILL CONTINUE TO MONITOR
FOR POSSIBLE HIGH WIND WARNING THIS EVENING.
LATEST RAP ANALYSIS SHOWS AROUND 40-45 KNOTS OF WIND AT 925 MB
THROUGH MID EVENING...MAINLY ALONG AND EAST OF THE HIGHWAY 83
CORRIDOR AND ALONG AND NORTH OF INTERSTATE 94. ALSO 850 KNOT WINDS
INCREASE EARLY THIS EVENING ACROSS MUCH OF CENTRAL NORTH DAKOTA.
AFTER COORDINATION WITH FGF...WILL EXTEND THE CURRENT WIND
ADVISORY FARTHER SOUTH TO ALONG AND NORTH OF INTERSTATE 94...AND
KEEP AN EYE ON WINDS ACROSS THE FAR NORTH CENTRAL...HOLDING OFF ON
A HIGH WIND WARNING AT THIS TIME.
OTHERWISE NO SIGNIFICANT CHANGES TO THE FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE HIGHLIGHT OF THE SHORT TERM CONTINUES TO BE THE IMPACTS OF THE
ONGOING RAINFALL EVENT.
OVERALL THE GUIDANCE IS IN GOOD AGREEMENT...AND FOLLOWED A BLEND
OF THE 12 UTC GFS/GEM/ECMWF AND 15 UTC SREF FOR ALL FIELDS.
CURRENTLY THE STACKED LOW ACROSS FAR NORTHEAST SOUTH DAKOTA IS
EXPECTED TO SLOWLY PROPAGATE INTO CENTRAL MINNESOTA THROUGH
TUESDAY. WRAP AROUND RAINFALL IS EXPECTED TO SLOWLY DOWNTREND
THROUGH THE NIGHT AND INTO TUESDAY WITH AN ADDITIONAL ONE HALF TO
THREE QUARTERS OF AN INCH OF RAINFALL EXPECTED. SEE THE HYDROLOGY
DISCUSSION BELOW FOR DETAILS.
FOR THIS EVENING AND TONIGHT...DID MAINTAIN THE WIND ADVISORY FOR
THE WEST AND NORTH. THE WIND FIELD ACROSS THESE AREAS CONTINUES TO
STRENGTHEN WITH 40-45 KTS AT THE TOP OF A SHALLOW MIXED LAYER AS
DEPICTED BY THE 12 UTC NAM/GFS BUFR SOUNDINGS. THE STRONGEST WINDS
ARE EXPECTED ACROSS THE TURTLE MOUNTAINS WHERE GUSTS TO NEAR 50
MPH ARE POSSIBLE THROUGH EARLY EVENING.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE MAIN FORECAST ISSUE THROUGH THE LONG TERM PERIOD WILL BE ONGOING
RIVER AND OVERLAND FLOODING CONCERNS. SEE HYDROLOGY DISCUSSION BELOW
FOR DETAILS. THEN ATTENTION TURNS TO THE UPCOMING WEEKEND AND THE
POSSIBILITY FOR SCATTERED THUNDERSTORMS AND POSSIBLE SEVERE WEATHER.
THERE IS FAIRLY GOOD MODEL AGREEMENT REGARDING THE POSITION AND
MOVEMENT OF THE CLOSED UPPER LEVEL LOW...ASSOCIATED WITH THE
PERSISTENT RAINS FOR THE PAST SEVERAL DAYS. THE UPPER LOW IS
FORECAST TO BE OVER THE SD/MN BORDER TUESDAY EVENING...THEN BECOME
MORE OF AN OPEN WAVE BY WEDNESDAY EVENING OVER IA/WI/IL AND THE
WESTERN GREAT LAKES. THIS SCENARIO WILL MEAN THE VERY HIGH/LIKELY
CHANCES OF RAIN TUESDAY NIGHT IN THE JAMES RIVER BASIN WILL LESSEN
TO SCATTERED IN NATURE BY WEDNESDAY. THE REST OF WESTERN AND CENTRAL
NORTH DAKOTA SHOULD SEE A DECREASE IN COVERAGE OF THE SHOWERS
TUESDAY NIGHT. SLIGHT CHANCES TO SCATTERED SHOWERS WEDNESDAY AS THE
SYSTEM MOVES EAST OF THE REGION.
BY WEDNESDAY EVENING AS THE UPPER LEVEL LOW/TROUGH MOVES EAST...A
WEAK UPPER LEVEL RIDGE WILL BUILD ACROSS THE NORTHERN PLAINS. THIS
WILL BE SHORT-LIVED AS ANOTHER LARGE UPPER LEVEL LOW/TROUGH SYSTEM
MOVES INTO THE PACIFIC NORTHWEST AND ROCKIES. THUS NO PRECIPITATION
MENTION FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
FRIDAY THROUGH THE WEEKEND AND INTO MONDAY...THE UPPER LEVEL LOW
OVER THE ROCKIES IS FORECAST TO REMAIN IN PLACE...SETTING UP A
PROLONGED PERIOD OF SOUTHWESTERLY FLOW ALOFT FOR NORTH DAKOTA. THIS
WILL MEAN PERIODIC UPPER LEVEL SHORTWAVE ENERGY MOVING NORTHEASTWARD
THROUGH THE MEAN FLOW. AT THE SURFACE...THIS WILL RESULT IN BROAD
LOW PRESSURE ACROSS THE PLAINS...ALLOWING PLENTY OF GULF OF MEXICO
MOISTURE TO STREAM NORTHWARD. A PROLONGED LOW LEVEL JET AT H925-H850
WILL HELP TRANSPORT MOISTURE AND ENERGY NORTHWARD UP THE PLAINS.
THUS PERIODIC EPISODES OF SCATTERED THUNDERSTORMS WILL BE IN THE
FORECAST FRIDAY THROUGH THE MEMORIAL DAY WEEKEND.
WHILE TOO FAR OUT FOR MUCH CERTAINTY IN NARROWING DOWN SPECIFIC
AREAS OF CONCERN...SURFACE DEWPOINTS RISING INTO THE 50S BY FRIDAY
AND FORECAST CAPE DEVELOPING FROM THE SOUTHERN...CENTRAL...TO THE
NORTHERN PLAINS WOULD SUGGEST SOME SEVERE THUNDERSTORM ACTIVITY OVER
A BROAD AREA OF THE PLAINS FRIDAY AND SATURDAY. STAY TUNED FOR LATER
FORECASTS AND STORM PREDICTION CENTER OUTLOOKS FOR THE POTENTIAL FOR
SEVERE THUNDERSTORMS THIS COMING WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 109 AM CDT TUE MAY 21 2013
LIGHT TO SOMETIMES MODERATE RAINFALL WILL CONTINUE OVER ALL
TERMINALS THROUGH THE TAF PERIOD WITH MVFR/IFR CIGS/VSBYS. WIND
GUSTS OF 30-40 KTS ARE POSSIBLE AT EASTERN TAF
SITES...KJMS...THROUGH THIS TUESDAY MORNING.
&&
.HYDROLOGY...
ISSUED AT 330 PM CDT MON MAY 20 2013
DID MAINTAIN THE FLOOD WATCH FOR ALL OF WESTERN AND CENTRAL NORTH
DAKOTA THROUGH TONIGHT. CALLS TO AREA EMERGENCY MANAGERS REVEAL THAT
FOR THE MOST PART...COUNTY AND TOWNSHIP ROAD IMPACTS ARE LIMITED.
HOWEVER...AS SOILS CONTINUE TO SATURATE...OVERLAND FLOOD CONCERNS
COULD INCREASE THROUGH THE NIGHT. FURTHERMORE...REPORTS HAVE BEEN
COMING IN OF WATER ENTERING BASEMENTS ACROSS THE AREA WITH THE
SATURATED GROUND. ADDITIONAL RIVER AND STREAM RISES ARE EXPECTED
OVER THE COMING DAYS. FOR THE MOST PART WITHIN BANK RISES ARE
ANTICIPATED. HOWEVER...THE SOURIS RIVER AT TOWNER IS EXPECTED TO
RISE ABOVE FLOOD STAGE AGAIN...THE PIPESTEM CREEK NEAR PINGREE IS
FORECAST TO RISE ABOVE MINOR FLOOD STAGE TOMORROW AFTERNOON WITH
THE WILLOW CREEK NEAR WILLOW CITY POSSIBLY APPROACHING FLOOD STAGE
BY WEDNESDAY EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 7 AM CDT /6 AM MDT/ THIS MORNING FOR
NDZ001>005-009>013-017>023-025-031>037-040>048-050-051.
WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR NDZ004-005-012-013-
022-023-025-036-037.
&&
$$
UPDATE...NH
SHORT TERM...AYD
LONG TERM...JV
AVIATION...NH
HYDROLOGY...AYD
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
605 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN IN PLACE THROUGH WEDNESDAY.
OCCASIONAL PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE.
A COLD FRONT WILL MOVE THROUGH THE REGION ON THURSDAY...BEFORE
COOLER AIR SETTLES IN ON FRIDAY AND INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SIGNIFICANT CHANGES WERE MADE TO THE FORECAST IN THE NEAR
TERM...AS A RAGGED MCS CURRENTLY MOVING ACROSS CENTRAL INDIANA
WILL CONTINUE ITS WAY INTO THE ILN FORECAST AREA THIS MORNING. ALL
MODELS...INCLUDING CONVECTIVE ALLOWING MODELS...FORECAST A GRADUAL
WEAKENING OF THIS FEATURE AS IT CONTINUES MOVING TO THE EAST.
MESOSCALE ANALYSIS SHOWS THE NEAR-SURFACE ENVIRONMENT IS VERY
UNFAVORABLE FOR THIS LINE TO MAINTAIN ITS STRENGTH...WITH MUCH MORE
INHIBITION (UP TO 100-150 J/KG) THAN WHEN IT WAS IN CENTRAL
INDIANA...AND A NEAR-SURFACE INVERSION OVER THE ILN CWA.
HOWEVER...AS SOME ELEVATED INSTABILITY WILL REMAIN IN PLACE...THE
CONVECTION IS NOT EXPECTED TO DISSIPATE ENTIRELY. THERE IS SOME
SHEAR IN PLACE IN THE LOW LEVELS (30-40 KNOTS FROM 0-1KM...WHICH
IS SOMEWHAT IMPRESSIVE). WINDS AHEAD OF THE LINE ARE GENERALLY OUT
OF THE SOUTH...AND WINDS AT 925MB ARE OUT OF THE SOUTHWEST AND UP
TO 40 KNOTS. THIS HAS LED TO SOME ISOLATED POCKETS OF STRONGER
WINDS ON THE LINE. HOWEVER...IT IS UNLIKELY THAT THIS SHEAR WILL
BE REALIZED OVER THE ILN CWA...GIVEN THE MORE HOSTILE
THERMODYNAMIC ENVIRONMENT. THUS...THE SEVERE THREAT THIS MORNING
APPEARS LOW...THOUGH SOME GUSTY WINDS WILL CERTAINLY BE POSSIBLE.
THE FOCUS FOR THE REST OF THE DAY IS ON THE POTENTIAL FOR
ADDITIONAL STORMS THIS AFTERNOON AND EVENING. THE FIRST CHALLENGE
IS A NEAR COMPLETE LACK OF PROPER MODELING OF THE CURRENT
CONVECTIVE COMPLEX. THE HRRR APPEARS TO BE THE CLOSEST...THOUGH IT
IS A COUPLE HOURS BEHIND. THE NAM SOLUTION...WHICH
FEATURES PRECIPITATION MOVING THROUGH INDIANA AND OHIO DURING THE
LATE MORNING AND EARLY AFTERNOON (3-6 HOURS BEHIND THE CURRENT
ACTIVITY) DOES NOT APPEAR RELIABLE. WITH A LACK OF SYNOPTIC SCALE
FORCING...MESOSCALE FEATURES WILL PLAY A BIG ROLE IN THE POTENTIAL
FOR STORMS...AND THESE FEATURES WILL BE HIGHLY DEPENDENT ON THE
EVOLUTION OF THE MORNING CONVECTION (PLACEMENT OF OUTFLOW / CLOUD
DEBRIS LIMITING DESTABILIZATION).
IN GENERAL...THE PATTERN WILL FAVOR THE GREATEST INSTABILITY IN
THE SOUTHERN PORTIONS OF THE FORECAST AREA...PERHAPS AS HIGH AS
1500-2500 J/KG OF MIXED LAYER CAPE. STILL A WAYS REMOVED FROM THE
BRUNT OF THE JET...THE ILN CWA WILL NOT GET INTO A GREAT DEAL OF
WIND SHEAR TODAY...PERHAPS UP TO 30 KNOTS IN THE DEEP LAYER AND
NOT MUCH AT ALL IN THE LOWEST LEVELS. THE INSTABILITY SHOULD BE
SURFACE BASED AND UNCAPPED (RAP13 FORECASTS SHOW A 3 DEG C DROP IN
700MB TEMPS BY AFTERNOON)...AND THIS APPEARS TO BE ENOUGH TO
SUPPORT SOME SEVERE THREAT. THE LACK OF STRONGER SHEAR AND
ORGANIZED FORCING SHOULD BE A LIMITING FACTOR. IT IS POSSIBLE THAT
THE MORNING CONVECTION MAY END UP LEAVING A BOUNDARY THAT COULD
ACT AS THE FOCUS FOR CONVECTIVE DEVELOPMENT IN THE AFTERNOON
HOURS.
THE TEMPERATURE FORECAST IS ALSO SIGNIFICANTLY DEPENDENT ON THE
ABOVE FACTORS...THOUGH THE AIR MASS IS CERTAINLY CAPABLE OF
SUPPORTING TEMPS AS HIGH AS THE MID TO UPPER 80S. RAW MODEL TEMPS
ARE IN WIDE VARIANCE FROM MODEL TO MODEL...WITH INTENSE HEATING
BEFORE PRECIPITATION FORCES DROPS IN THE SURFACE TEMP FIELDS (AND
AT DIFFERENT TIMES AND PLACES). WHILE A GENERAL CONSENSUS WAS
USED...IN THE INTEREST OF BEING A BIT CONSERVATIVE GIVEN THE
UNCERTAIN CONVECTIVE FORECAST...THE MAX TEMPS WERE KNOCKED DOWN A
COUPLE DEGREES FROM THERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
CONVECTION WILL LIKELY BE ONGOING FOR AT LEAST PART OF THE
FORECAST AREA DURING THE TUESDAY EVENING HOURS...WITH A DIURNAL
MIN LEADING TO MORE TRANQUIL CONDITIONS OVERNIGHT. HOWEVER...BY
WEDNESDAY MORNING...THIS MAY BEGIN TO CHANGE AGAIN. A SHORTWAVE
MOVING OUT OF THE SOUTHERN PLAINS WILL EVENTUALLY MAKE ITS WAY
JUST EAST OF THE ILN CWA BY MORNING...WITH MODEL AGREEMENT ON AN
ASSOCIATED CONVECTIVE COMPLEX SPREADING INTO INDIANA BY THEN.
MEANWHILE...SURFACE LOW PRESSURE WILL STRENGTHEN AS IT MOVES
THROUGH ILLINOIS AND INTO MICHIGAN...WITH GENERAL SURFACE
TROUGHING AND HEIGHT FALLS ALOFT SPREADING INTO THE ILN CWA. THIS
IS A FAVORABLE ENVIRONMENT FOR LIFT...AND SHOULD SUPPORT A LIKELY POP
FORECAST THROUGH MOST OF THE DAY WEDNESDAY. ALTHOUGH GENERALLY
UNIDIRECTIONAL...THE INCREASING PRESSURE GRADIENT AND
JUXTAPOSITION WITH THE RIGHT ENTRANCE REGION OF THE UPPER JET WILL
ALSO SUPPORT AN INCREASED BIT OF SHEAR AND FORCING (RESPECTIVELY).
THE LIMITING FACTOR FOR SEVERE POTENTIAL WILL BE
INSTABILITY...WHICH DOES NOT APPEAR TO BE PARTICULARLY STRONG (AND
THIS IS NOT SURPRISING GIVEN THE LACK OF EXPECTED SURFACE
HEATING). TEMPS ALOFT WILL CONTINUE TO DROP...WHICH SHOULD HELP
GENERATE 500-1000 J/KG IF SOME SUN CAN BE REALIZED. AN ALTERNATE
POSSIBILITY WOULD KEEP PRECIPITATION OVER THE CWA THROUGH THE
MORNING AND EARLY AFTERNOON...ESSENTIALLY LIMITING DESTABILIZATION
TO NEAR-ZERO. THE SOUNDINGS LOOK RATHER MOIST...LEADING TO THIN
CAPE AND LOW LCLS.
IT IS AN INTERESTING CONTRAST IN SEVERE POTENTIAL FROM TODAY
(TUESDAY)...WITH DIFFERENT ELEMENTS OF THE MESOSCALE ANALYSIS
APPEARING FAVORABLE ON EITHER DAY.
THE LARGE NORTHERN PLAINS UPPER LOW WILL FINALLY BE ON THE MOVE BY
LATE WEDNESDAY...CROSSING THE ILN CWA ON THURSDAY. THIS WILL BRING
ANOTHER HIGH CHANCE OF POPS ON THURSDAY...MAINLY IN THE NORTH AND
GENERALLY WITH DIURNAL TIMING. BEHIND THE AXIS OF THIS
TROUGH...RAPID DRYING IS EXPECTED.
TEMPERATURES WILL BEGIN A DOWNWARD TREND AFTER THE POORLY-DEFINED
COLD FRONT (ASSOCIATED WITH THE WEDNESDAY SURFACE LOW) MOVES
THROUGH THE REGION. A STRONGER CHANGE IN NEAR-SURFACE AIR MASS IS
EXPECTED BEHIND THE TROUGH ON THURSDAY NIGHT...WITH NORTHERLY
WINDS ADVECTING COLDER AND DRIER AIR INTO THE REGION.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL BUILD DOWN FROM THE NORTH AND INTO OUR
AREA FRIDAY INTO SATURDAY...KEEPING A SEASONABLY COOL AIRMASS IN
PLACE THROUGH THE START OF THE WEEKEND. HIGHS ON FRIDAY WILL BE IN
THE MID TO UPPER 60S AND WITH THE SURFACE HIGH OVERHEAD...LOWS
SATURDAY MORNING WILL DIP INTO THE LOW TO MID 40S. THE SURFACE
HIGH WILL BEGIN TO SHIFT OFF TO THE EAST THROUGH THE REMAINDER OF
THE WEEKEND AS MID LEVEL RIDGING BEGINS TO ESTABLISH ITSELF ALOFT.
THIS WILL RESULT IN A GRADUAL RETURN TO WARMER TEMPERATURES
THROUGH THE REST OF THE HOLIDAY WEEKEND. MODELS ARE STILL TRYING
TO SUGGEST THE POSSIBILITY OF SOME ENERGY DROPPING DOWN FROM THE
NORTHWEST LATE IN THE WEEKEND. HOWEVER...TIMING AND PLACEMENT ARE
HIGHLY VARIABLE SO WILL MAINTAIN A DRY FORECAST AT THIS POINT.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
LARGE SCALE UPPER LEVEL LOW CENTERED OVER THE NORTHERN PLAINS WILL
MAKE LITTLE EASTWARD PROGRESSION OVER THE NEXT 24 HOURS. REGION
WILL BE LOCATED IN A WARM...MOIST SOUTH/SOUTHWEST FLOW AT THE SFC
AND ALOFT.
FIRST ITEM OF CONCERN WILL BE A CLUSTER OF CONVECTION ONGOING
ACROSS SOUTHWEST INDIANA AND WESTERN KENTUCKY. IT IS UNCLEAR HOW
MUCH OF THIS WILL HOLD IN TACT AS IT PUSHES TOWARD THE KCVG AND KLUK
TERMINALS BETWEEN 12Z AND 15Z SO HAVE INCLUDED A VCTS/CB AT
THESES TAF SITES BUT WILL MAKE A LAST MINUTE DECISION BASED ON
RADAR TRENDS IF A TEMPO GROUP IS NEEDED. AS OUR AREA IS IN A MOIST
SOUTHWEST FLOW ALOFT...ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY
WILL BE DEPENDENT ON ANY LINGER OUTFLOW BOUNDARIES FROM EARLY
MORNING CONVECTION...EMBEDDED DISTURBANCES ALOFT AND HOW MUCH
SUNSHINE THE AREA RECEIVES FOR INSTABILITY. MODELS ARE NOT
OFFERING MUCH IN TERMS OF SPECIFIC TIMING EXCEPT TO FAVOR THE
DIURNAL CYCLE AND HAVE INCLUDE ONLY VCTS/CB AT THE TAF SITES AS
SUCH. THIS MAY SIGNIFICANTLY CHANGE DEPENDING ON PREVIOUS
MENTIONED FACTORS IF THUNDERSTORMS GET GOING ON ANY MESOSCALE
FEATURE.
FOR TONIGHT...MODELS SUGGEST A LULL IN THE CONVECTIVE ACTIVITY IN
TERMS OF COVERAGE. COVERAGE SHOULD INCREASE ON WEDNESDAY AS A MORE
SIGNIFICANT DISTURBANCE ROTATES FROM SOUTHWEST TO NORTHEAST ACROSS
THE REGION OUT AHEAD OF A COLD FRONT. SHOWERS AND THUNDERSTORMS
LOOK LIKE A GOOD BET FOR WEDNESDAY INTO WEDNESDAY EVENING.
OUTLOOK...THUNDERSTORMS LIKELY WEDNESDAY INTO WEDNESDAY EVENING.
MVFR CONDITIONS POSSIBLE THURSDAY INTO THURSDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
428 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN IN PLACE THROUGH WEDNESDAY.
OCCASIONAL PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE.
A COLD FRONT WILL MOVE THROUGH THE REGION ON THURSDAY...BEFORE
COOLER AIR SETTLES IN ON FRIDAY AND INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SIGNIFICANT CHANGES WERE MADE TO THE FORECAST IN THE NEAR
TERM...AS A RAGGED MCS CURRENTLY MOVING ACROSS CENTRAL INDIANA
WILL CONTINUE ITS WAY INTO THE ILN FORECAST AREA THIS MORNING. ALL
MODELS...INCLUDING CONVECTIVE ALLOWING MODELS...FORECAST A GRADUAL
WEAKENING OF THIS FEATURE AS IT CONTINUES MOVING TO THE EAST.
MESOSCALE ANALYSIS SHOWS THE NEAR-SURFACE ENVIRONMENT IS VERY
UNFAVORABLE FOR THIS LINE TO MAINTAIN ITS STRENGTH...WITH MUCH MORE
INHIBITION (UP TO 100-150 J/KG) THAN WHEN IT WAS IN CENTRAL
INDIANA...AND A NEAR-SURFACE INVERSION OVER THE ILN CWA.
HOWEVER...AS SOME ELEVATED INSTABILITY WILL REMAIN IN PLACE...THE
CONVECTION IS NOT EXPECTED TO DISSIPATE ENTIRELY. THERE IS SOME
SHEAR IN PLACE IN THE LOW LEVELS (30-40 KNOTS FROM 0-1KM...WHICH
IS SOMEWHAT IMPRESSIVE). WINDS AHEAD OF THE LINE ARE GENERALLY OUT
OF THE SOUTH...AND WINDS AT 925MB ARE OUT OF THE SOUTHWEST AND UP
TO 40 KNOTS. THIS HAS LED TO SOME ISOLATED POCKETS OF STRONGER
WINDS ON THE LINE. HOWEVER...IT IS UNLIKELY THAT THIS SHEAR WILL
BE REALIZED OVER THE ILN CWA...GIVEN THE MORE HOSTILE
THERMODYNAMIC ENVIRONMENT. THUS...THE SEVERE THREAT THIS MORNING
APPEARS LOW...THOUGH SOME GUSTY WINDS WILL CERTAINLY BE POSSIBLE.
THE FOCUS FOR THE REST OF THE DAY IS ON THE POTENTIAL FOR
ADDITIONAL STORMS THIS AFTERNOON AND EVENING. THE FIRST CHALLENGE
IS A NEAR COMPLETE LACK OF PROPER MODELING OF THE CURRENT
CONVECTIVE COMPLEX. THE HRRR APPEARS TO BE THE CLOSEST...THOUGH IT
IS A COUPLE HOURS BEHIND. THE NAM SOLUTION...WHICH
FEATURES PRECIPITATION MOVING THROUGH INDIANA AND OHIO DURING THE
LATE MORNING AND EARLY AFTERNOON (3-6 HOURS BEHIND THE CURRENT
ACTIVITY) DOES NOT APPEAR RELIABLE. WITH A LACK OF SYNOPTIC SCALE
FORCING...MESOSCALE FEATURES WILL PLAY A BIG ROLE IN THE POTENTIAL
FOR STORMS...AND THESE FEATURES WILL BE HIGHLY DEPENDENT ON THE
EVOLUTION OF THE MORNING CONVECTION (PLACEMENT OF OUTFLOW / CLOUD
DEBRIS LIMITING DESTABILIZATION).
IN GENERAL...THE PATTERN WILL FAVOR THE GREATEST INSTABILITY IN
THE SOUTHERN PORTIONS OF THE FORECAST AREA...PERHAPS AS HIGH AS
1500-2500 J/KG OF MIXED LAYER CAPE. STILL A WAYS REMOVED FROM THE
BRUNT OF THE JET...THE ILN CWA WILL NOT GET INTO A GREAT DEAL OF
WIND SHEAR TODAY...PERHAPS UP TO 30 KNOTS IN THE DEEP LAYER AND
NOT MUCH AT ALL IN THE LOWEST LEVELS. THE INSTABILITY SHOULD BE
SURFACE BASED AND UNCAPPED (RAP13 FORECASTS SHOW A 3 DEG C DROP IN
700MB TEMPS BY AFTERNOON)...AND THIS APPEARS TO BE ENOUGH TO
SUPPORT SOME SEVERE THREAT. THE LACK OF STRONGER SHEAR AND
ORGANIZED FORCING SHOULD BE A LIMITING FACTOR. IT IS POSSIBLE THAT
THE MORNING CONVECTION MAY END UP LEAVING A BOUNDARY THAT COULD
ACT AS THE FOCUS FOR CONVECTIVE DEVELOPMENT IN THE AFTERNOON
HOURS.
THE TEMPERATURE FORECAST IS ALSO SIGNIFICANTLY DEPENDENT ON THE
ABOVE FACTORS...THOUGH THE AIR MASS IS CERTAINLY CAPABLE OF
SUPPORTING TEMPS AS HIGH AS THE MID TO UPPER 80S. RAW MODEL TEMPS
ARE IN WIDE VARIANCE FROM MODEL TO MODEL...WITH INTENSE HEATING
BEFORE PRECIPITATION FORCES DROPS IN THE SURFACE TEMP FIELDS (AND
AT DIFFERENT TIMES AND PLACES). WHILE A GENERAL CONSENSUS WAS
USED...IN THE INTEREST OF BEING A BIT CONSERVATIVE GIVEN THE
UNCERTAIN CONVECTIVE FORECAST...THE MAX TEMPS WERE KNOCKED DOWN A
COUPLE DEGREES FROM THERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
CONVECTION WILL LIKELY BE ONGOING FOR AT LEAST PART OF THE
FORECAST AREA DURING THE TUESDAY EVENING HOURS...WITH A DIURNAL
MIN LEADING TO MORE TRANQUIL CONDITIONS OVERNIGHT. HOWEVER...BY
WEDNESDAY MORNING...THIS MAY BEGIN TO CHANGE AGAIN. A SHORTWAVE
MOVING OUT OF THE SOUTHERN PLAINS WILL EVENTUALLY MAKE ITS WAY
JUST EAST OF THE ILN CWA BY MORNING...WITH MODEL AGREEMENT ON AN
ASSOCIATED CONVECTIVE COMPLEX SPREADING INTO INDIANA BY THEN.
MEANWHILE...SURFACE LOW PRESSURE WILL STRENGTHEN AS IT MOVES
THROUGH ILLINOIS AND INTO MICHIGAN...WITH GENERAL SURFACE
TROUGHING AND HEIGHT FALLS ALOFT SPREADING INTO THE ILN CWA. THIS
IS A FAVORABLE ENVIRONMENT FOR LIFT...AND SHOULD SUPPORT A LIKELY POP
FORECAST THROUGH MOST OF THE DAY WEDNESDAY. ALTHOUGH GENERALLY
UNIDIRECTIONAL...THE INCREASING PRESSURE GRADIENT AND
JUXTAPOSITION WITH THE RIGHT ENTRANCE REGION OF THE UPPER JET WILL
ALSO SUPPORT AN INCREASED BIT OF SHEAR AND FORCING (RESPECTIVELY).
THE LIMITING FACTOR FOR SEVERE POTENTIAL WILL BE
INSTABILITY...WHICH DOES NOT APPEAR TO BE PARTICULARLY STRONG (AND
THIS IS NOT SURPRISING GIVEN THE LACK OF EXPECTED SURFACE
HEATING). TEMPS ALOFT WILL CONTINUE TO DROP...WHICH SHOULD HELP
GENERATE 500-1000 J/KG IF SOME SUN CAN BE REALIZED. AN ALTERNATE
POSSIBILITY WOULD KEEP PRECIPITATION OVER THE CWA THROUGH THE
MORNING AND EARLY AFTERNOON...ESSENTIALLY LIMITING DESTABILIZATION
TO NEAR-ZERO. THE SOUNDINGS LOOK RATHER MOIST...LEADING TO THIN
CAPE AND LOW LCLS.
IT IS AN INTERESTING CONTRAST IN SEVERE POTENTIAL FROM TODAY
(TUESDAY)...WITH DIFFERENT ELEMENTS OF THE MESOSCALE ANALYSIS
APPEARING FAVORABLE ON EITHER DAY.
THE LARGE NORTHERN PLAINS UPPER LOW WILL FINALLY BE ON THE MOVE BY
LATE WEDNESDAY...CROSSING THE ILN CWA ON THURSDAY. THIS WILL BRING
ANOTHER HIGH CHANCE OF POPS ON THURSDAY...MAINLY IN THE NORTH AND
GENERALLY WITH DIURNAL TIMING. BEHIND THE AXIS OF THIS
TROUGH...RAPID DRYING IS EXPECTED.
TEMPERATURES WILL BEGIN A DOWNWARD TREND AFTER THE POORLY-DEFINED
COLD FRONT (ASSOCIATED WITH THE WEDNESDAY SURFACE LOW) MOVES
THROUGH THE REGION. A STRONGER CHANGE IN NEAR-SURFACE AIR MASS IS
EXPECTED BEHIND THE TROUGH ON THURSDAY NIGHT...WITH NORTHERLY
WINDS ADVECTING COLDER AND DRIER AIR INTO THE REGION.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL BUILD DOWN FROM THE NORTH AND INTO OUR
AREA FRIDAY INTO SATURDAY...KEEPING A SEASONABLY COOL AIRMASS IN
PLACE THROUGH THE START OF THE WEEKEND. HIGHS ON FRIDAY WILL BE IN
THE MID TO UPPER 60S AND WITH THE SURFACE HIGH OVERHEAD...LOWS
SATURDAY MORNING WILL DIP INTO THE LOW TO MID 40S. THE SURFACE
HIGH WILL BEGIN TO SHIFT OFF TO THE EAST THROUGH THE REMAINDER OF
THE WEEKEND AS MID LEVEL RIDGING BEGINS TO ESTABLISH ITSELF ALOFT.
THIS WILL RESULT IN A GRADUAL RETURN TO WARMER TEMPERATURES
THROUGH THE REST OF THE HOLIDAY WEEKEND. MODELS ARE STILL TRYING
TO SUGGEST THE POSSIBILITY OF SOME ENERGY DROPPING DOWN FROM THE
NORTHWEST LATE IN THE WEEKEND. HOWEVER...TIMING AND PLACEMENT ARE
HIGHLY VARIABLE SO WILL MAINTAIN A DRY FORECAST AT THIS POINT.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
LARGE SCALE UPPER LEVEL LOW CENTERED OVER THE NORTHERN PLAINS WILL
MAKE LITTLE EASTWARD PROGRESSION OVER THE NEXT 24 HOURS. REGION
WILL BE LOCATED IN A WARM...MOIST SOUTH/SOUTHWEST FLOW AT THE SFC
AND ALOFT.
FIRST ITEM OF CONCERN WILL BE THE QLCS TO OUR WEST ACROSS WESTERN
INDIANA AND EASTERN ILLINOIS. SOME MODELS WEAKEN THIS FEATURE TO
THE POINT THAT IT IS GONE BY THE TIME IT GETS NEAR OUR WESTERN TAF
SITES BETWEEN 09Z AND 12Z. OTHER MODELS TRY TO HOLD IT TOGETHER
INTO OUR WESTERN TAF SITES BEFORE COMPLETELY WEAKENING IT. AT THIS
TIME...HAVE NOT PLACED ANY CONVECTION IN THE TAFS AND WILL MONITOR
LINE/TRENDS AND UPDATE/AMEND ACCORDINGLY IF NECESSARY.
OTHERWISE...THE TIMING OF CONVECTION FOR TODAY IS FAIRLY MURKY AS
MODELS ARE NOT HANDLING MESOSCALE FEATURES AT THE SURFACE AND
ALOFT WELL. KEPT PREVIOUS FORECAST TREND TO ALLOW FOR SHOWERS AND
THUNDERSTORMS DURING THE PEAK HEATING OF THE DAY FOLLOWED BY A
LULL IN ACTIVITY THIS EVENING. FOR LATE TONIGHT INTO WEDNESDAY...A
MORE BONAFIDE DISTURBANCE AND DEVELOPING LOW LEVEL JET WILL LIKELY
BRING WIDESPREAD PRECIPITATION TO OUR AREA...BUT EXACT TIMING IS
STILL IN QUESTION AT THIS POINT. WINDS TODAY WILL BE LOCALLY GUSTY
FROM THE SOUTHWEST TO 25 KNOTS WITH GUSTINESS SUBSIDING TOWARD
SUNSET.
OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM TUESDAY NIGHT THROUGH
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
125 AM EDT TUE MAY 21 2013
.SYNOPSIS...
HIGH PRESSURE OVERNIGHT. AFTERNOON CONVECTION TUESDAY AND
WEDNESDAY. COLD FRONT APPROACHES WEDNESDAY AND MOVES ACROSS
THURSDAY. COOLER HIGH PRESSURE FRIDAY AND THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
INTRODUCE AREAS OF FOG MAINLY OVER AREAS THAT RECEIVED RAIN DURING
THE AFTERNOON HOURS...AND OVER TYGART RIVER AND KANAWHA RIVER
VALLEYS...AND THE SOUTHERN COAL FIELDS OF WEST VIRGINIA DURING THE
PREDAWN HOURS. ADJUSTED HOURLY TEMPS CURVE. REMOVED ALL PCPN
THROUGH 12Z TUESDAY. MODELS SHOWING NO DISTURBANCES AT H5 WITHIN UPPER
RIDGE ACROSS NORTHEAST KY...OH...WV...AND PA. FOR
TUESDAY...AFTERNOON SHOWERS AND STORMS ARE POSSIBLE.
PREVIOUS DISCUSSION BELOW...
RADAR IMAGERY AT 18Z SHOWING SHOWERS WITH A FEW EMBEDDED
THUNDERSTORMS MAINLY CONFINED TO THE EASTERN HIGHER TERRAIN AT
THIS POINT. EXPECT THIS PRECIP TO CONTINUE EASTWARD AS THE S/W
TROUGH AND ASSOC VORT MAX RESPONSIBLE FOR TODAY/S PRECIP CONTINUES
EAST AS WELL. LATEST SFC OBS AND RUC13 CONTINUE TO DEPICT SOME SFC
CONVERGENCE WITH WEAK TROUGH ACROSS THE FAR WESTERN ZONES THIS
AFTERNOON. BEST LLVL MOISTURE HAS PUSHED EASTWARD AND NEAR-TERM
CONVECTIVE MODELS DO NOT SHOW ANY REDEVELOPMENT ACROSS THE WEST.
WILL HOWEVER GO AHEAD AND CONTINUE A SLIGHT CHANCE FOR CONVECTION
OUT HERE WITH JUST A PINCH OF LLVL MOISTURE STILL NOTED ON POINT
SOUNDINGS AND PWATS UP AROUND 1.2-1.4 INCHES.
DURING THE OVERNIGHT HOURS TODAY/S S/W TROUGH AND VORT MAX CONTINUE
EASTWARD. PRECIP WILL HAVE ENDED FOR MOST IF NOT ALL LOCATIONS BTWN
00Z-03Z TUE. MOST LOCATIONS WILL REMAIN PRECIP-FREE OVERNIGHT BUT
LATEST NWP GUIDANCE DEPICTING A 2-3KFT LAYER OF CONVECTIVE MOISTURE
PUSHING INTO THE NORTHERN ZONES CENTERED AROUND 850MB AND AROUND 12Z
TUE. SIMULTANEOUSLY 850MB CONVERGENCE NOTED ACROSS THE I-79 CORRIDOR
AS WELL AND THUS WILL BRING IN SLIGHT CHANCE POPS WITH THUNDER WITH
THIS FEATURE. INHERITED MINS IN THE LOW/MID 60S MOST LOWLAND
LOCATIONS LOOK GOOD. WILL CONTINUE TO CARRY AT LEAST A SLIGHT CHANCE
OF SHOWERS/THUNDER MOST LOCATION DURING THE DAY...BUT THE BETTER
CHANCE OF THUNDERSTORMS ARRIVES SE OHIO ZONES BY AND AFTER 21Z AS
BETTER LLVL MOISTURE ARRIVES WITH DECENT SFC CONVERGENCE NOTED SAME
AREA. SHEAR IS WEAK AND THUS ORGANIZATION WILL BE AS WELL WITH
REGARD TO SEVERE POTENTIAL. BUT HEAVY DOWNPOURS WILL BE POSSIBLE AND
WITH SOME STRONG WINDS.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
MAIN WEATHER MAKER THROUGH THE SHORT TERM WILL BE THE SURFACE COLD
FRONT PASSING WEDNESDAY...AND THEN THE LINGER UPPER LEVEL TROUGH.
FOR TUESDAY NIGHT...MAIN FOCUS IS TO THE WEST...SO DECREASED POPS
SOME...HOWEVER WITH LOTS OF MOISTURE STILL HANGING AROUND COULD NOT
GO DRY SO HAVE SLIGHT CHANCE TO CHANCE POPS FOR MUCH OF THE AREA
OVERNIGHT. COLD FRONT APPROACHES FROM THE WEST WEDNESDAY...WILL
LIKELY BE ONGOING CONVECTION/OUTFLOW BOUNDARIES TO OUR WEST
WEDNESDAY MORNING. WE SHOULD HAVE PLENTY OF INSTABILITY IN THE
WARM SECTOR AHEAD OF THE FRONT...NAM IS SHOWING 2000+ J/KG CAPE
ALONG THE OHIO RIVER AROUND NOON...WITH 30-40KTS BULK SHEER AND
PWATS AROUND 1.5 INCHES. SHOULD SEE A ROUND OF ORGANIZED
CONVECTION OUT AHEAD OF THE COLD FRONT MOVING FROM WEST TO EAST
ACROSS THE CWA. THE MOST LIKELY AREA OF CONCERN FOR STRONG TO
SEVERE STORMS CONTINUES TO BE ALONG AND EITHER SIDE OF THE OHIO
RIVER FROM SE OHIO INTO NORTH CENTRAL WEST VIRGINIA. WILL CONTINUE
HWO MENTION FOR DAMAGING WINDS AND HAIL POTENTIAL. THE ACTUAL COLD
FRONT WILL NOT PASS UNTIL THURSDAY...SO POPS CONTINUE THROUGH THE
SHORT TERM PERIOD.
WEDNESDAY WILL BE A WARM DAY...BUT WITH PLENTY OF CLOUDS SHOULD NOT
BE AS WARM AS TUESDAY. THURSDAY WILL BE ABOUT 10 DEGREES COOLER.
OVERNIGHT LOWS WILL BE MILD WITH LOTS OF CLOUDS AND MOISTURE.
BASED ON RECENT VERIFICATION STATS...BLENDED IN BIAS- CORRECTED
CONSENSUS GUIDANCE FOR BOTH HIGHS AND LOWS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HAVE GENERALLY FOLLOWED WPC THINKING FOR THIS PORTION OF THE FORECAST.
COLD FRONT SHOULD BE LOCATED SOUTHEAST OF THE REGION AT THE
BEGINNING OF THE PERIOD...WITH HIGH PRESSURE BUILDING IN. CHANCE
OF SHOWERS AND STORMS WILL END FROM THE NORTHWEST THURSDAY NIGHT
INTO FRIDAY. HOWEVER...A MID-LEVEL DISTURBANCE MOVING SOUTHEAST
WILL INCREASE THE CHANCES FOR PRECIPITATION ON FRIDAY....MAINLY IN
THE MOUNTAINS AND ADJACENT COUNTIES.
HIGH PRESSURE WILL THEN BE IN CONTROL OF THE AREA INTO MONDAY.
HOWEVER...A WEAK MID-LEVEL DISTURBANCE WILL SLIDE SOUTHEAST SATURDAY
NIGHT INTO SUNDAY.
A WARM FRONT WILL DEVELOP AND APPROACH THE REGION ON MONDAY. ECMWF
SUGGESTS THERE WILL BE A CHANCE OF SHOWERS AND STORMS MONDAY
AFTERNOON...ESPECIALLY ACROSS THE SOUTH. BECAUSE OF UNCERTAINTY...HAVE
LEFT THESE CHANCES OUT OF THE FORECAST FOR NOW.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
PATCHY DENSE FOG CAN BE EXPECTED IN VALLEYS IN AND JUST WEST OF THE
MOUNTAINS THAT RECEIVED RAIN TODAY. FURTHER WEST AND ON
HILLTOPS...WINDS SHOULD PREVENT THE DENSE FOG. CUMULUS CAN BE
EXPECTED TODAY...WITH AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE...MODERATE WITH FOG EARLY THIS MORNING...THEN
HIGH.
ALTERNATE SCENARIOS: SOME UNCERTAINTY ON FOG DENSITY AND COVERAGE
OVERNIGHT. TIMING OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON COULD
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 05/21/13
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H M H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L L L L L L L L H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 06Z WEDNESDAY...
IFR CONDITIONS POSSIBLE WEDNESDAY WITH SHOWERS AND THUNDERSTORMS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/ARJ/50
NEAR TERM...ARJ/50
SHORT TERM...MZ
LONG TERM...JSH
AVIATION...RPY
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1228 AM CDT TUE MAY 21 2013
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY
AXIS OF SHOWERS HAS SHIFTED INTO THE EASTERN CWA THIS
AFTERNOON...WITH A BREAK FOR COUNTIES WEST OF ABERDEEN. THIS BREAK
WILL BE SHORT LIVED AS RADARS UPSTREAM IN NORTH DAKOTA ARE QUITE
ACTIVE...WITH WIDESPREAD LIGHT/MODERATE RAINFALL. HRRR AND RUC
GUIDANCE PIVOTS THIS MOISTURE BACK OVER THE CWA THIS EVENING AND
PERSISTS WELL INTO TUESDAY. MOST OF THE AREA HAS BEEN ABLE TO
HANDLE THE MOISTURE THUS FAR...WITH A FEW SPOTS REPORTING RISING
WATER IN DITCHES/CREEKS BUT NOT MUCH IMPACT OTHERWISE. SREF
PROBABILITIES FOR GREATER THEN A QUARTER INCH ARE HIGHEST ACROSS
OUR NORTHERN MISSOURI RIVER COUNTIES...AN AREA THAT HAS NOT
RECEIVED MUCH DROUGHT RELIEF THIS SPRING...AND THUS THINK THAT AREA
CAN HANDLE THE ADDITIONAL 1/2 INCH OF RAIN. SOILS FARTHER SOUTH
AND EAST MAY BE LESS FORGIVING AND WILL NEED TO BE MONITORED THIS
EVENING/OVERNIGHT FOR WATER ISSUES.
AS THE STACKED LOW CONTINUES TO DRIFT EAST TUESDAY...LIFT WEAKENS
WITH SOME DRIER AIR ENTRAINMENT RESULTING IN LOWER PROBABILITY FOR
PRECIPITATION AND QPF. TEMPERATURES THIS PERIOD WILL REMAIN BELOW
NORMAL AND CHANGE LITTLE THANKS TO CLOUD COVER.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
AS THE PERIOD OPENS...A DECAYING UPPER LOW CIRCULATION OVER THE
REGION WILL BE SLOWLY DRIFTING SOUTHEAST OUT OF THE AREA.
CONTINUED WRAP-AROUND MOISTURE COMBINED WITH SOME WEAK TROWALESQUE
FORCING/LIFT WILL KEEP POPS/RAIN SHOWERS MENTION GOING TUESDAY
NIGHT INTO WEDNESDAY AS THIS LOW PULLS AWAY FROM THE REGION.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT SHOULD BE DRY FORECAST
PERIODS WHILE A TRANSIENT HIGH-AMPLITUDE LONGWAVE HIGH PRESSURE
RIDGE WORKS THROUGH THE REGION.
BY FRIDAY...LOW LEVEL RETURN FLOW IS IN FULL SWING AND POPS FOR
SHOWERS AND THUNDERSTORMS MAKE THEIR RETURN TO THE FORECAST AS MID
AND UPPER LEVEL FLOW TAKES ON A RATHER PROLONGED PERIOD OF SWRLY
FLOW...THAT IS CURRENTLY PROGGED BY THE GFS AND ECMWF TO LAST
RIGHT INTO MONDAY.
THE COOLEST TEMPS DURING THE PERIOD LOOK TO BE TUESDAY NIGHT AND
WEDNESDAY BEFORE THE WARMING TREND ENSUES. BY THE
WEEKEND...TEMPERATURES SHOULD BE MUCH CLOSER TO CLIMO NORMAL.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
AN AREA OF RAIN WILL CONTINUE TO SPIN OVER MUCH OF CENTRAL AND
NORTHEASTERN SOUTH DAKOTA OVERNIGHT AND THROUGH THE DAY TUESDAY.
CIGS AND VSBYS WILL VARY BETWEEN VFR AND MVFR LEVELS WITH THE
RAINFALL. BREEZY NORTHERLY WINDS OF 20 TO 30 MPH WILL AFFECT KPIR
AND KMBG.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...WISE
SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...WISE
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1202 AM CDT TUE MAY 21 2013
.UPDATE...
&&
.AVIATION...
06Z TAFS...SOME MVFR BR OR PERHAPS PATCHY STRATUS IS POSSIBLE
OVERNIGHT. STORMS OVER AR/MO WILL APPROACH FROM THE WEST...BUT
THINK THEY WILL MOSTLY DIMINISH BEFORE REACHING MID TN. S WINDS
WILL BECOME SOMEWHAT GUSTY ON TUESDAY...TO 20KT AT
TIMES...ESPECIALLY FOR CKV. THE CHANCE FOR TSRA WILL INCREASE LATE
IN THE TAF PERIOD WITH AN APPROACHING DISTURBANCE. SCT
COVERAGE...SO JUST INCLUDING A VCTS FOR CKV/BNA.
13
&&
.PREV DISCUSSION... /ISSUED 854 PM CDT MON MAY 20 2013/
UPDATE...
HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO REFLECT CLEAR SKIES
ACROSS THE MID STATE THRU THE EVENING HRS...WITH A GENERAL INCREASE
OF CLOUDINESS WEST TO EAST ACROSS THE MID STATE AFTER MIDNIGHT. HAVE
ALSO MENTIONED PATCHY FOG AFTER MIDNIGHT PLATEAU PER CONTINUED LOW
LEVEL MOISTURE POOLING POTENTIAL. WITH SOME UNCERTAINTIES CONCERNING
ACTUAL CLOUD COVERAGE LATE...WILL CONTINUE TO GO CLOSE TO CURRENT
FORECAST REASONING ON OVERNIGHT LOWS.
PREV DISCUSSION... /ISSUED 324 PM CDT MON MAY 20 2013/
AFTERNOON CU DEVELOPMENT IS WIDESPREAD ACROSS THE MID STATE THIS
AFTERNOON AS DEWPOINTS HAVE CONTINUED TO RISE. MID LEVEL CAP IS
RATHER STRONG ACCORDING TO THE 12Z SOUNDING FROM THIS MORNING. THE
HIGHER DEWPOINTS HAVE ACTED TO LOWER CONVECTIVE TEMPS BUT CURRENT
TEMPS ARE STRUGGLING TO RISE GIVEN THE EXTRA CLOUD COVER.
FOR TONIGHT`S FORECAST...WILL INCLUDE A 20 POP BUT ONLY FOR THE
NW. THIS IS IN LINE WITH THE HRRR REFLECTIVITY FCST WHICH SHOWS
LITTLE IF ANY DEVELOPMENT. OVERALL...IT JUST APPEARS THAT THERE IS
TOO MUCH VERTICAL DRYNESS IN PLACE.
A SLIGHT CHANCE OF SHOWERS AND TSTMS WILL BE IN THE FCST AGAIN FOR
TUESDAY. MOISTURE LEVELS SHOULD BE HIGHER AND WE DO SEE MORE 18Z CAP
EROSION WITH THE GFS MODEL. THE INCREASE IN MOISTURE WILL BE AIDED
BY AN APPROACHING FRONTAL BOUNDARY WHICH WILL IMPACT THE AREA LATE
TUESDAY NIGHT AND INTO WEDNESDAY. AT THAT TIME...A SLIGHT RISK OF
SEVERE WEATHER IS IN THE FCST FOR OUR NW COUNTIES. BEST OMEGA
FORCING APPEARS TO BE AROUND 06Z WEDNESDAY ACROSS WESTERN TN.
BUT...THERE COULD BE A FEW STRONGER CELLS OVER THAT SAME AREA
EARLIER ON TUES AFTERNOON. STORM MOTION SHOULD RUN FROM SW TO NE.
SHOWERS AND TSTMS TO PERSIST INTO WEDNESDAY. ITS IMPORTANT TO NOTE
HOWEVER THAT OVERALL POPS WITH THIS SYSTEM ARE NOT DRASTICALLY HIGH.
IN FACT...MODELS NOT LEANING TOWARD DEEP MOISTURE WITH A WIDESPREAD
AREA OF RAIN OCCURRING. NEVERTHELESS...POPS IN THE 40-60 PERCENT
RANGE WILL BE INCLUDED FOR TUESDAY NT INTO WEDNESDAY. AFTER A FEW
LINGERING SHOWERS ON THURSDAY ACROSS THE PLATEAU...CLEARING WILL
OCCUR WITH DRIER AIR MOVING IN.
FOR THE NEAR TERM TEMPS...WILL AGAIN UNDERCUT THE HIGH TEMPS FOR
TUESDAY AND WEDNESDAY. OVERNIGHT LOWS FROM THE GUIDANCE APPEARS
REASONABLE.
IN THE EXT FCST...NICE LATE MAY CONDITIONS ARE ON TAP FOLLOWING THE
FROPA WHICH WAS MENTIONED IN THE SHORT TERM TIME FRAME.
THUS...SUNSHINE TO RETURN IN EARNEST FOR FRIDAY AND INTO THE
WEEKEND. THERMAL TROUGHING WILL BE SLOW TO GIVE WAY AND
THUS...MOSTLY SUNNY SKIES WITH BELOW NORMAL TEMPS AND LOWER
HUMIDITY LEVELS WILL PREVAIL THU THROUGH SAT. SUNDAY AND MONDAY...UPPER
RIDGING AND HEIGHT RISES WILL BE ON TAP. THIS WILL EQUATE TO HIGH
TEMPS BACK UP INTO THE 80S. BUT...STILL NOT SEEING ANY APPRECIABLE
PRECIP CHANCES THROUGH MONDAY.
21
&&
.OHX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
459 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
AS OF 145 AM EDT MONDAY...
MANY OBSERVATIONS HAVE NOT BEEN TRANSMITTED SINCE 04Z/MIDNIGHT DUE
TO AN OUTAGE IN NATIONAL COMMUNICATIONS CENTER. UNTIL DATA FLOW IS
RESUMED...HAVE ADDED...AMD NOT SKED...TO THE END OF THE TAFS.
EXPECT AREAS OF FOG AND STRATUS OVERNIGHT. IFR TO LIFR CEILINGS
ARE LIKELY BY 09Z/4AM. LOCATIONS THAT HAD RAIN ON MONDAY WILL HAVE
FOG...INCLUDING ROA AND DAN.
A SHORT WAVE OVER THE AREA TONIGHT MOVES INTO EASTERN VIRGINIA
TODAY. ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP AGAIN THIS
AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS TOO LOW TON INCLUDE
IN THE TAF AT THIS TIME.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
PATCHY FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ009-
012>020-022>024.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ001-002-
018.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
422 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT TUESDAY...
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
AS OF 145 AM EDT MONDAY...
MANY OBSERVATIONS HAVE NOT BEEN TRANSMITTED SINCE 04Z/MIDNIGHT DUE
TO AN OUTAGE IN NATIONAL COMMUNICATIONS CENTER. UNTIL DATA FLOW IS
RESUMED...HAVE ADDED...AMD NOT SKED...TO THE END OF THE TAFS.
EXPECT AREAS OF FOG AND STRATUS OVERNIGHT. IFR TO LIFR CEILINGS
ARE LIKELY BY 09Z/4AM. LOCATIONS THAT HAD RAIN ON MONDAY WILL HAVE
FOG...INCLUDING ROA AND DAN.
A SHORT WAVE OVER THE AREA TONIGHT MOVES INTO EASTERN VIRGINIA
TODAY. ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP AGAIN THIS
AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS TOO LOW TON INCLUDE
IN THE TAF AT THIS TIME.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
PATCHY FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
400 AM CDT TUE MAY 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CDT TUE MAY 21 2013
AT 345 AM...SHOWERS AND ISOLATED THUNDERSTORMS WERE FOUND ALONG AND
NORTH OF THE INTERSTATE 94 CORRIDOR. THIS PRECIPITATION WAS
CONTINUING TO DEVELOP IN THE RIGHT ENTRANCE REGION OF A 110 KNOT
250 MB JET. THE 21.00Z MESO MODELS ARE IN VERY GOOD AGREEMENT THAT
THE PRECIPITATION WILL CONTINUE TO MOVE NORTHEAST AWAY FROM NORTH
CENTRAL WISCONSIN EARLY THIS MORNING. FURTHER TO THE WEST...A
CLOSED UPPER LEVEL LOW REMAINED OVER THE EASTERN DAKOTAS.
FOR TODAY...THE MESO MODELS ARE IN GOOD AGREEMENT THAT WEAK TO
MODERATE 900-700 MB FRONTOGENESIS WILL REMAIN ACROSS NORTHERN
WISCONSIN AND CENTRAL MINNESOTA. IN ADDITION...THE ML CAPE WILL BE
CLIMBING UP TO 500 J/KG FOR LATE THIS MORNING AND AFTERNOON. THIS
WILL RESULT IN THE DEVELOPMENT OF SHOWERS AND ISOLATED
THUNDERSTORMS ALONG AND NORTH OF THE INTERSTATE 94 CORRIDOR. WITH
0-3 KM AND 0-6 KM SHEAR GENERALLY LESS 25 KNOTS...NO SEVERE
WEATHER IS EXPECTED.
FOR TONIGHT...THE 900-700 MB FRONTOGENESIS WILL PROVIDE A CHANCE
OF SHOWERS AND ISOLATED THUNDERSTORMS CONTINUING NORTH OF THE
INTERSTATE 94 CORRIDOR. MEANWHILE WITH THE CLOSED LOW WILL
APPROACHING THE AREA FROM THE DAKOTAS...AND A SHORT WAVE
TROUGH...CURRENTLY OVER NEW MEXICO...MOVING NORTHEAST ACROSS
NORTHERN ILLINOIS AND SOUTHWEST WISCONSIN WILL RESULT IN ISOLATED
TO SCATTERED SHOWERS MOVING INTO THE REMAINDER OF THE FORECAST
AREA AFTER MIDNIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 358 AM CDT TUE MAY 21 2013
FROM WEDNESDAY INTO WEDNESDAY NIGHT...THE CLOSED LOW WILL OPEN UP
INTO AN OPEN WAVE AND MOVE EAST THROUGH THE FORECAST AREA. THIS
EVENTUALLY EVOLVED INTO A DEFORMATION BAND OF PRECIPITATION MOVING
EAST THROUGH THE FORECAST AREA. THE HIGHEST PRECIPITATION CHANCES
WILL LIKELY RUN FROM THE LATE MORNING INTO THE EARLY EVENING. WITH
BOTH THE 0-3 KM AND 0-6 KM SHEAR LESS THAN 25 KNOTS...NONE OF THE
THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE.
ON THURSDAY NIGHT...A CANADIAN HIGH PRESSURE SYSTEM WILL USHER IN
DEW POINTS OF AROUND 30 DEGREES INTO CENTRAL AND NORTH CENTRAL
WISCONSIN. IN ADDITION...THE CLEAR SKIES AND LIGHT WINDS WILL
ALLOW FOR VERY GOOD RADIATIVE COOLING. LOW TEMPERATURES ON FRIDAY
MORNING WILL LIKELY FALL INTO THE MID 30S ACROSS THIS REGION.
THERE EVEN COULD BE SOME LOWER 30S IN THE CRANBERRY BOGS OF
CENTRAL WISCONSIN. DUE TO THIS ADDED SOME PATCHY FROST INTO THE
FORECAST FOR THESE AREAS.
ON FRIDAY NIGHT AND SATURDAY MORNING...MODERATE WARM AIR ADVECTION
AND ISENTROPIC LIFT WILL DEVELOP ACROSS SOUTHEAST MINNESOTA...
NORTHEAST IOWA...AND WESTERN WISCONSIN. THIS IS IN RESPONSE TO THE
UPPER LEVEL RIDGE BUILDING TOWARD THE AREA. IN ADDITION...WEAK TO
MODERATE 850 MB MOISTURE TRANSPORT WILL LIKELY RESULT IN THE
DEVELOPMENT OF A MESOSCALE CONVECTIVE COMPLEX ACROSS NORTHWEST
MINNESOTA DURING THE EVENING AND THEN THE SYSTEM WILL MOVE
SOUTHEAST THROUGH OUR AREA FROM THE LATE EVENING INTO SATURDAY
MORNING. WITH PRECIPITABLE WATER VALUES RUNNING AROUND 1.2
INCHES...THERE COULD POTENTIALLY BE SOME BRIEF PERIODS OF HEAVY
RAIN WITH THIS COMPLEX. WHILE THE 0-6KM SHEAR REMAIN LESS THAN
30 KNOTS...THE 0-3KM SHEAR WILL BECOME FAVORABLE ACROSS SOUTHEAST
MINNESOTA AND NORTHEAST IOWA THAT THERE COULD POTENTIALLY BE A
WIND THREAT WITH THESE STORMS.
FROM SATURDAY THROUGH MEMORIAL DAY...THE MODELS CONTINUE TO DIFFER
ON THE LOCATION OF THE CANADIAN HIGH. THE ECMWF CONTINUES TO
SUGGEST THAT THE HIGH WILL KEEP THE AREA DRY THROUGHOUT THIS TIME
PERIOD. MEANWHILE THE GFS...CONTINUES TO KEEP THE HIGH MORE OVER
THE GREAT LAKES AND THIS KEEPS US IN THE ACTIVE AREA ON THE EAST
SIDE OF THE UPPER LEVEL RIDGE. SINCE BOTH MODELS HAVE CHANGED
LITTLE...DECIDED TO JUST STAY WITH THE ALL BLEND FOR NOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1202 AM CDT TUE MAY 21 2013
THUNDERSTORM ACTIVITY CONTINUES TO MOVE OFF THE NORTHEAST AHEAD OF
THE SHORT WAVE TROUGH MOVING ACROSS WESTERN IOWA. THE 21.00Z NAM
SHOWS THIS WAVE LIFTING NORTHEAST PAST THE AREA OVERNIGHT AND THE
GENERAL CONSENSUS FROM THE NAM...21.03Z RAP AND HRRR IS THAT THIS
ACTIVITY WILL LIFT NORTHEAST OF THE TAF SITES BY 09Z. PLAN TO
HAVE A TEMPO GROUP FOR THUNDER IN AT KLSE THROUGH 08Z FOLLOWED BY
VCTS FOR A SHORT PERIOD AND JUST CARRY A VCTS AT KRST THROUGH 08Z
AS RADAR SHOWS JUST SCATTERED ACTIVITY BACK ACROSS NORTHERN IOWA.
THE SURFACE LOW ACROSS NORTHEAST SOUTH DAKOTA IS EXPECTED TO MOVE
INTO EASTERN WISCONSIN BY TUESDAY AFTERNOON. THIS WILL ALLOW THE
COLD FRONT TO SWING THROUGH WITH A WIND SWITCH TO THE SOUTHWEST
DURING THE MID TO LATE MORNING. SATELLITE AND SURFACE OBS SHOW
LOTS OF VFR CEILINGS IN PLACE AROUND THE SURFACE LOW SO WILL SHOW
A CEILING AROUND 4K FEET FOR BOTH SITES FOR FROM MID MORNING
THROUGH THE REMAINDER OF THE PERIOD.
&&
.HYDROLOGY...
ISSUED AT 358 AM CDT TUE MAY 21 2013
RAINFALL ON WEDNESDAY AND WEDNESDAY EVENING WILL LIKELY BE LESS
THAN A QUARTER OF AN INCH ACROSS NORTHEAST IOWA AND SOUTHEAST
MINNESOTA. THIS RAINFALL WILL LIKELY JUST SLOW THE FALLS ON AREA
RIVERS AND STREAMS.
ON FRIDAY NIGHT AND SATURDAY...ANOTHER QUARTER TO HALF INCH OF
RAIN WILL LIKELY FALL ACROSS SOUTHEAST MINNESOTA AND NORTHEAST
IOWA. LIKE WEDNESDAY...THIS RAIN WILL LIKELY ONLY SLOW THE FALL ON
AREA RIVERS AND STREAMS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...04
HYDROLOGY...BOYNE
AREA FORECAST DISCUSSION
NWS ALBANY NY
1045 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS ESPECIALLY NORTH OF THE IMMEDIATE CAPITAL REGION. THE HUMID
AND UNSETTLED WEATHER CONTINUES TOMORROW AND THURSDAY WITH MORE
CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A COLD FRONT RETURNS
DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1030 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM SECTOR WITH
SKY COVERAGE BEGINNING TO CLEAR OUT SOUTH OF THE IMMEDIATE CAPITAL
REGION. A STATIONARY BOUNDARY IS SITTING JUST NORTH OF THE
IMMEDIATE CAPITAL REGION WHERE IT IS GENERATING A FEW SHOWERS OVER
THE NY/VT BORDER.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS
OR STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE IN A GENERA-LY WEST TO EAST MANNER.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
SOME TYPICAL EARLY MORNING LOW CLOUDS AND FOG AFFECTING ALL SITES
AND SHOULD LIFT BY 14Z WHEN CONDITIONS SHOULD BECOME VFR...EXCEPT
BY 16Z AT KPSF. THERE IS ANOTHER SMALL CLUSTER OF SHOWERS AND
THUNDERSTORMS OVER LAKE ONTARIO THAT COULD APPROACH KGFL LATE THIS
MORNING OR EARLY THIS AFTERNOON...BUT TOO EARLY AND TOO ISOLATED
TO MENTION IN TAF AT THIS TIME OTHER THAN PUTTING A VCSH.
MORE SHOWERS AND THUNDERSTORMS IN THE OH VALLEY AND CENTRAL GREAT
LAKES THIS MORNING COULD AFFECT OUR REGION LATE THIS AFTERNOON AND
EVENING...IF THEY HOLD TOGETHER TO TRACK THIS FAR EAST. AGAIN...DUE
TO UNCERTAINTIES...JUST PUTTING VCSH AT ALL SITES THIS AFTERNOON AND
EVENING. LATER IN THE EVENING...SOME FOG AND LOW CEILINGS COULD
POTENTIALLY FORM WITH MVFR CONDITIONS.
LIGHT WINDS SHOULD BECOME SOUTH TO SOUTHWEST AT 10 KT OR LESS
TODAY...THEN DIMINISH BACK TO LIGHT THIS EVENING AND TONIGHT.
OUTLOOK...
WED...VFR/MVFR CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -TSRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS/LFM
NEAR TERM...FRUGIS/LFM
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1019 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A BACKDOOR COLD FRONT WILL DROP SOUTH ACROSS THE REGION LATE
TONIGHT AND TUESDAY RESULTING IN BRIEFLY COOLER WEATHER ACROSS
EASTERN NEW ENGLAND AND CHANCE OF THUNDERSTORMS IN WESTERN NEW
ENGLAND. WARM AND HUMID CONDITIONS CONTINUE INTO THURSDAY AND
FRIDAY WITH SCATTERED SHOWERS AND STRONG THUNDERSTORMS POSSIBLE. A
COOLER AND LESS HUMID AIR MASS IS EXPECTED FOR THE COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
10 AM UPDATE...
CLOUDS HAVE CLEARED ACROSS MUCH OF THE REGION...EXCEPT LOW CLOUDS
AND FOG CONTINUED ACROSS PORTIONS OF E COASTAL MA. MODELS SUGGEST
CLOUDS AND FOG WILL BRIEFLY ERODE THROUGH ABOUT 18Z...THEN LOW
CLOUDS FROM THE N AND NE WILL EXPAND SW ACROSS THE REGION 18-00Z
AS THE BACKDOOR FRONT PUSHES SW. THIS FRONT WILL REMAIN ACROSS
FAR NE ZONES INTO THE AFTERNOON WHICH WILL ALLOW TEMPS TO REACH
INTO THE 80S ACROSS A GOOD PORTION OF THE AREA...WITH UPPER 80S
LOWER CT VALLEY. COOLER READINGS WILL BE FOUND ALONG THE S COAST
AND ESPECIALLY NE MA AND SE NH AND THIS COOLER AIR WILL MOVE SW
AFT 18Z WITH TEMPS FALLING SHARPLY THROUGH THE 70S AND INTO THE
60S BY EVENING ACROSS MUCH OF EASTERN HALF OF NEW ENG...WITH 50S
NE MA.
NEXT CONCERN IS POTENTIAL FOR CONVECTION. SPC MESOANALYSIS
ALREADY SHOWING MLCAPES INCREASING TO 1000 J/KG IN THE CT VALLEY
AND EXPECT MLCAPES 1000-2000 J/KG ACROSS CENTRAL AND WESTERN NEW
ENG THIS AFTERNOON WITH HIGHER CAPES BECOMING MORE FOCUSED IN THE
CT VALLEY LATE AFTERNOON AS THE FRONT PUSHES SW. MID LEVEL LAPSE
RATES ARE FAVORABLE AROUND 6.5-7 C/KM. DEEP LAYER SHEAR IS
MARGINAL BUT VALUES 20-30 KT ARE CERTAINLY ENOUGH TO SUPPORT
SOME ORGANIZATION OF ANY STORMS THAT DEVELOP. SO WE ARE EXPECTING
SCT TSTMS TO DEVELOP IN THE INTERIOR WITH POTENTIAL FOR A FEW
STRONG TO SEVERE STORMS. HRRR IS TARGETING MASS PIKE REGION EARLY
THIS AFTERNOON WITH ACTIVITY SHIFTING FURTHER WEST TO THE CT
VALLEY MID/LATE AFTERNOON.
&&
.SHORT TERM /WEDNESDAY/...
BACK-DOOR COLD FRONT SHOULD MOVE FARTHER NORTH LATE TONIGHT INTO
WEDNESDAY AS A WARM FRONT. THIS SHOULD ALLOW FOR A WARMER DAY
ACROSS EASTERN MA. STILL NOT CONVINCED SYNOPTIC FLOW WILL BE
STRONG ENOUGH TO PREVENT LOCAL SEABREEZES FROM DEVELOPING...SO
TEMPERATURES WILL BE TRICKY ALONG THE IMMEDIATE COASTLINES.
AM CURRENTLY EXPECTING A BRIEF DIMINISHMENT OF ANY CONVECTION
LATE TONIGHT INTO WEDNESDAY MORNING...AS SUGGESTED BY CLIMATOLOGY.
INSTABILITY REGENERATES WEDNESDAY AFTERNOON...SO KEPT AT LEAST A
CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST. THE LOWEST
RISK FOR SHOWERS AND THUNDERSTORMS WILL BE ACROSS THE CAPE AND
ISLANDS...WHERE ANOTHER ROUND OF LOW CLOUDS AND FOG WILL KEEP
TEMPERATURES LOWER.
USED A BLEND OF MOS GUIDANCE ONCE AGAIN FOR TEMPERATURES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
HIGHLIGHTS...
* SCATTERED SHOWERS AND THUNDERSTORMS THURS INTO FRIDAY
* COOLER AND LESS HUMID FOR THE WEEKEND
CONFIDENCE LEVEL/MODEL GUIDANCE...MODERATE CONFIDENCE IN THE
OVERALL FORECAST...YET LOW CONFIDENCE ON MODEL PERFORMANCE. THE
00Z GFS/NAM SIGNIFICANTLY SLOWED DOWN THE DIGGING TROUGH FOR THE
NORTHEAST. THE REST OF THE MODEL GUIDANCE FOLLOWED SUIT BUT NOT AS
DRASTICALLY. LEANED FORECAST TOWARDS EC/UKMET WHICH WHERE IN
BETWEEN THE 12Z AND 00Z GUIDANCE AS WELL AS PREV FORECAST. OVERALL
HAVE HIGH CONFIDENCE THAT PRECIP WILL OCCUR THURS AND MODERATE
CONFIDENCE FOR FRIDAY. HIGH CONFIDENCE IN A COOL DOWN FOR THE WEEK
WITH MOD CONFIDENCE FOR SEASONAL TEMPS AND DRY FORECAST FOR
BEGINNING OF THE WORK WEEK.
DETAILS...
THURSDAY INTO FRIDAY...
APPROACHING UPPER LEVEL TROUGH WILL BRING A ROUND OF PRECIP AND
THUNDER TO THE REGION. STILL SOME TIMING ISSUES AS MODELS STILL
DIFFER ON EXACT LOCATION AND MESOSCALE PARAMETERS.
REGARDLESS...SOUTHERN NEW ENGLAND WILL BE LOCATED IN THE WARM SECTOR
OF THE SYSTEM ALLOWING HIGHER DEWPOINTS AND THEREFORE MUGGY
CONDITIONS. TEMPS WILL WARM INTO THE 80S. BELIEVE DIURNAL PRECIP
WILL BE THE MAIN TREAT FOR THIS DAY...WITH STRONG STORMS POSSIBLE.
MAIN THREAT OF THESE STORMS WILL BE HAIL...STRONG WINDS AND HEAVY
DOWNPOURS. A COLD FRONT WILL BEGIN TO APPROACH THE REGION THURSDAY
NIGHT AND MOVE THROUGH THE AREA ON FRIDAY. THIS WILL CHANGE THE
CONVECTIVE MODE TO MORE OF A POSSIBLE SQUALL LINE ON FRIDAY.
CONVECTIVE PARAMETERS APPEAR TO BE MORE IN LINE DUE TO THE SLOW DOWN
OF THE OVERALL SYSTEM. ONLY THING TRULY LACKING IS THE AMOUNT OF
INSTABILITY AS CLOUD DEBRIS WILL BE AROUND FROM THE PREV NIGHTS
SHOWERS/THUNDER. IF STORMS DO DEVELOP THEN BELIEVE THE MAIN THREAT
WILL BE STRONG WINDS AND HEAVY DOWNPOURS AS PWATS REACH CLOSE TO 1.5
IN.
THIS WEEKEND...
UPPER LEVEL TROUGH WILL PUSH THROUGH OVER THE WEEK...CAA WILL
BRING A THERMAL TROUGH INTO THE REGION. THIS WILL DROP TEMPS WELL
BELOW SEASONAL AVG. AM NOT ANTICIPATED ANY FROST/FREEZE HEADLINES
AT THIS TIME BUT MAY NEED TO MONITOR IN THE FUTURE AS THE ENTIRE
AREA IS NOW IN THE GROWING SEASON. EXPECT MAINLY DRY WEATHER FOR
THE WEEKEND AND TEMPS IN THE MID TO UPPER 60S.
MONDAY AND BEYOND...SURFACE HIGH PRESSURE WILL BE IN CONTROL FOR
THE FIRST HALF OF NEXT WEEK. THIS WILL HELP TEMPS REACH SEASONAL
CONDITIONS. APPEARS THAT THERE IS LIMITED MOISTURE...HOWEVER
CANNOT RULE OUT A SPOT SHOWER OR TWO...ESP IF SEA BREEZE DEVELOPS.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...MODERATE CONFIDENCE IN TIMING AND AREAL COVERAGE OF
STRATUS AND FOG BOTH THIS MORNING AND WEDNESDAY MORNING.
PATCHY IFR CONDITIONS PORTIONS OF E COASTAL MA AND CAPE/ISLANDS
MAY BRIEFLY IMPROVE TO VFR FOR A TIME EARLY THIS
AFTERNOON...EXCEPT IFR FOG PERSISTING AT ACK. SHOWERS AND
THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON...ESPECIALLY ACROSS THE
INTERIOR.
TONIGHT...WIDESPREAD IFR/LIFR IN STRATUS AND FOG REDEVELOP.
WEDNESDAY...PRETTY MUCH A REPEAT OF TUESDAY. GRADUAL IMPROVEMENT
TO VFR/MVFR FROM WEST TO EAST.
KBOS TERMINAL...MODERATE CONFIDENCE. CONDITIONS SHOULD
TEMPORARILY IMPROVE TO VFR AROUND MIDDAY BUT FALL BACK TO IFR BY
MID TO LATE AFTERNOON. TIMING UNCERTAIN.
KBDL TERMINAL...MODERATE CONFIDENCE.
OUTLOOK...THURSDAY THROUGH SATURDAY...
THURSDAY INTO FRIDAY...LOW TO MODERATE CONFIDENCE.
MODERATE CONFIDENCE ON SEA BREEZE DEVELOPMENTS. VERY UNSETTLED
PATTERN WITH VARIABILITY BETWEEN VFR CONDITIONS AND MVFR/IFR
CONDITIONS IN SHRA/TSRA/FOG. IMPROVING CONDITIONS LATE FRIDAY
NIGHT INTO SATURDAY MORNING.
SATURDAY...HIGH CONFIDENCE. VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH WEDNESDAY.
WINDS AND SEAS EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA MOST OF TODAY. LEANED MORE HEAVILY UPON THE SWAN WAVE
GUIDANCE AS THE WNA WAVE GUIDANCE APPEARS TO BE TOO HIGH. STILL
EXPECTING AREAS OF FOG TO PERSIST THROUGH TODAY BEFORE EXPANDING
ONCE AGAIN TONIGHT.
INCREASING SOUTHWEST WINDS WEDNESDAY MAY LEAD TO DEVELOPMENT OF
MARGINAL 5 FT SEAS ACROSS THE SOUTHERN OUTER COASTAL WATERS OF MA
AND RI. WILL HOLD OFF ON ISSUING ANOTHER SMALL CRAFT ADVISORY
RIGHT NOW TO AVOID CONFUSION WITH EXISTING ADVISORY.
OUTLOOK...THURSDAY THROUGH SATURDAY...
THURSDAY INTO FRIDAY...HIGH CONFIDENCE. APPROACHING STORM SYSTEM
WILL INCREASE SEAS ABOVE 5FT DURING THIS TIME PERIOD...SCA WILL BE
NEEDED. EXPECT LOW VSBYS IN HEAVY SHOWERS AND SOME THUNDER AS WELL.
BELIEVE FRIDAY IS THE BETTER DAY FOR TSTORMS ACROSS THE WATERS AS
COLD FRONT WILL PUSH THROUGH NEW ENGLAND ON FRIDAY.
THIS WEEKEND...MODERATE CONFIDENCE. SEAS WILL REMAIN ABOVE SCA
FOR MOST OF THE WEEKEND ESP FOR THE OUTER WATERS. GUSTY NW BEHIND
THE FRONT WILL BRING GUSTS CLOSE TO GALE FORCE SAT INTO SAT NIGHT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR MAZ006-007-
015-016-019>024.
NH...NONE.
RI...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR RIZ006>008.
MARINE...NONE.
&&
$$
SYNOPSIS...BELK/DUNTEN
NEAR TERM...BELK/KJC/DUNTEN
SHORT TERM...BELK
LONG TERM...DUNTEN
AVIATION...BELK/KJC/DUNTEN
MARINE...BELK/DUNTEN
AREA FORECAST DISCUSSION
NWS ALBANY NY
729 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS. THE HUMID AND UNSETTLED WEATHER CONTINUES TOMORROW AND
THURSDAY WITH MORE CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A
COLD FRONT RETURNS DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE
HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 630 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM
SECTOR...WITH A VERY SLOW MOVING BOUNDARY SITUATED ACROSS THE
NORTHERN PORTION OF OUR AREA.
A LINE OF CONVECTIVE SHOWERS/THUNDERSTORMS SWEPT THROUGH THE
ADIRONDACKS EARLY THIS MORNING AND IS ALREADY WELL EAST OF THE
REGION ACROSS CENTRAL AND EASTERN NEW ENGLAND. ADDITIONAL SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ALONG THE STALLED BOUNDARY ACROSS
LAKE ONTARIO. SOME OF THESE SHOWERS/STORMS MAY MAKE IT INTO THE
ADIRONDACKS BY THE MID MORNING HOURS. OTHERWISE...THE REMAINDER OF
THE REGION WILL START THE DRY RAIN FREE...ALTHOUGH IT WILL WARM
AND MUGGY. SOME VALLEY AREAS ARE SEEING PATCHY FOG TO START THE
DAY...BUT THE STRONG MAY SUN SHOULD HELP DISSIPATE THIS FOG BY
ABOUT 8 AM.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS
OR STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE IN A GENERA-LY WEST TO EAST MANNER.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. SPC HAS PLACED OUR REGION IN A
/SEE TEXT/ AREA FOR TODAY...AND WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
SOME TYPICAL EARLY MORNING LOW CLOUDS AND FOG AFFECTING ALL SITES
AND SHOULD LIFT BY 14Z WHEN CONDITIONS SHOULD BECOME VFR...EXCEPT
BY 16Z AT KPSF. THERE IS ANOTHER SMALL CLUSTER OF SHOWERS AND
THUNDERSTORMS OVER LAKE ONTARIO THAT COULD APPROACH KGFL LATE THIS
MORNING OR EARLY THIS AFTERNOON...BUT TOO EARLY AND TOO ISOLATED
TO MENTION IN TAF AT THIS TIME OTHER THAN PUTTING A VCSH.
MORE SHOWERS AND THUNDERSTORMS IN THE OH VALLEY AND CENTRAL GREAT
LAKES THIS MORNING COULD AFFECT OUR REGION LATE THIS AFTERNOON AND
EVENING...IF THEY HOLD TOGETHER TO TRACK THIS FAR EAST. AGAIN...DUE
TO UNCERTAINTIES...JUST PUTTING VCSH AT ALL SITES THIS AFTERNOON AND
EVENING. LATER IN THE EVENING...SOME FOG AND LOW CEILINGS COULD
POTENTIALLY FORM WITH MVFR CONDITIONS.
LIGHT WINDS SHOULD BECOME SOUTH TO SOUTHWEST AT 10 KT OR LESS
TODAY...THEN DIMINISH BACK TO LIGHT THIS EVENING AND TONIGHT.
OUTLOOK...
WED...VFR/MVFR CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -TSRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
630 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS. THE HUMID AND UNSETTLED WEATHER CONTINUES TOMORROW AND
THURSDAY WITH MORE CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A
COLD FRONT RETURNS DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE
HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 630 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM
SECTOR...WITH A VERY SLOW MOVING BOUNDARY SITUATED ACROSS THE
NORTHERN PORTION OF OUR AREA.
A LINE OF CONVECTIVE SHOWERS/THUNDERSTORMS SWEPT THROUGH THE
ADIRONDACKS EARLY THIS MORNING AND IS ALREADY WELL EAST OF THE
REGION ACROSS CENTRAL AND EASTERN NEW ENGLAND. ADDITIONAL SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ALONG THE STALLED BOUNDARY ACROSS
LAKE ONTARIO. SOME OF THESE SHOWERS/STORMS MAY MAKE IT INTO THE
ADIRONDACKS BY THE MID MORNING HOURS. OTHERWISE...THE REMAINDER OF
THE REGION WILL START THE DRY RAIN FREE...ALTHOUGH IT WILL WARM
AND MUGGY. SOME VALLEY AREAS ARE SEEING PATCHY FOG TO START THE
DAY...BUT THE STRONG MAY SUN SHOULD HELP DISSIPATE THIS FOG BY
ABOUT 8 AM.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS
OR STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE IN A GENERA-LY WEST TO EAST MANNER.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. SPC HAS PLACED OUR REGION IN A
/SEE TEXT/ AREA FOR TODAY...AND WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
MOSTLY CLEAR SKY ACROSS THE REGION EARLY THIS MORNING...WITH A WEAK
WARM FRONT ACROSS NORTHERN NY. SOME FOG HAS FORMED AT KPSF AND
ACKNOWLEDGING IFR FOG TEMPORARILY MVFR THROUGH ABOUT 14Z AT KPSF. A
BAND OF SHOWERS AND THUNDERSTORMS OVER LAKE ONTARIO IS MOVING
EAST...AND THE SOUTHERN EDGE OF THE CONVECTION IS NEAR KSYR. THERE
IS A GUST FRONT AHEAD OF THE CONVECTION THAT IS MOVING AT AROUND 35
KT...BUT BASED ON THE STEERING FLOW SEEN ON RADARS ACROSS THE
REGION...THIS CONVECTION SHOULD MAINLY TRACK DUE EAST.
AREA 00Z SOUNDINGS ALSO SHOW ENOUGH INSTABILITY ACROSS THE REGION TO
SUSTAIN THE CONVECTION AS IT TRACKS THROUGH EASTERN NY AND INTO
WESTERN NEW ENGLAND. HOWEVER...IT IS TIMED TO REACH THE HUDSON
VALLEY AROUND 09Z...AND WITH CONTINUED STABILIZING OF THE ATMOSPHERE
THROUGH THE EARLY MORNING HOURS...AND WEAKENING OF THE
CONVECTION...JUST INDICATING VCSH AT KGFL...KALB AND KPSF...ALTHOUGH
THE BEST CHANCE OF A SHOWER OR THUNDERSTORM WOULD BE KGFL BASED ON
RADAR TRENDS. WILL AMEND TAFS AN HOUR OR TWO PRIOR TO A SHOWER OR
THUNDERSTORM IF RADAR SUGGESTS STRENGTH OF CONVECTION AND MOVEMENT
CONTINUES.
OUTSIDE OF THESE SHOWERS AND THUNDERSTORMS...SOME PATCHY MVFR FOG
AND SOME SCATTERED VARIABLE BROKEN CLOUDS AROUND 1500 FEET ARE
POSSIBLE THROUGH ABOUT 14Z. ONCE WHATEVER RAIN TRACKS EAST OF THE
REGION...BROKEN CLOUDS ABOVE 3000 FEET TEMPORARILY SCATTERED THROUGH
THE AFTERNOON. SOME SCATTERED SHOWERS OR THUNDERSTORMS COULD
DEVELOP LATE IN THE AFTERNOON AND INTO THE EVENING...BUT NO REAL
ORGANIZED FOCUS SO LEAVING OUT ANY VCSH FOR NOW...BUT MAY BE ADDED
IN LATER TAF ISSUANCES TODAY ONCE THE CHARACTER OF CONVECTION IS
KNOWN WHEN IT FORMS.
WINDS SHOULD BE NEARLY CAL THROUGH ABOUT 14Z. WINDS SHOULD BECOME
LIGHT SOUTH TO SOUTHWEST AT LESS THAN 10 KT LATER THIS MORNING AND
CONTINUE THIS AFTERNOON AND EVENING.
OUTLOOK...
TUE NIGHT...VFR/MVFR. AT KALB AND KGFL -SHRA LIKELY WITH CHC TSRA.
AT KPSF AND KPOU CHC -SHRA/-TSRA.
WED...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -SHRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
745 AM EDT TUE MAY 21 2013
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH THURSDAY. A COLD FRONT
WILL DROP THROUGH THE AREA ON FRIDAY WITH DRY HIGH PRESSURE BUILDING
IN NEXT WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NEAR DAWN...ANOTHER MILD MORNING ACROSS THE REGION AS A MOIST
ATMOSPHERE PERSISTS OVER THE FORECAST AREA. WATER VAPOR SATELLITE
IMAGERY INDICATES A WEAK MID LOW LEVEL LOW PRESSURE NOT FAR FROM
JACKSONVILLE FLORIDA...EMBEDDED IN A 500 MB TROUGH AXIS THAT RUNS
N THROUGH CHARLESTON TO GREENSBORO NC. AREAS OF LAYERED CLOUDS
EARLY THIS MORNING WITH POCKETS OF STRATUS AND FOG OVER INLAND
AREAS. WEAK UPPER DIFLUENCE AND MOIST COASTAL CONVERGENCE NOTED
ON LATEST MESOANALYSIS OVER EASTERN SOUTH CAROLINA AND AN AREA OF
HEAVY RAINFALL WAS EASING INTO NE CHARLESTON COUNTY AND WEAKENING
AFTER DUMPING PLENTY OF RAIN OVER SOUTHERN BERKELEY COUNTY. RADAR
ESTIMATED RAINFALL OVER 4 INCHES OF RAIN SE OF CYPRESS GARDENS.
TODAY...THE UPPER TROUGH DOES NOT MOVE MUCH AND EMBEDDED FEATURES
TEND TO WEAKEN WITH TIME. THE DEEPEST MOISTURE CONTINUES TO RESIDE
OVER SE SOUTH CAROLINA ALONG AND E OF INTERSTATE 95 INCLUDING THE
CHARLESTON AND CENTRAL SOUTH CAROLINA COASTAL AREAS. THROUGH MIDDAY
CONVECTIVE RAINS WILL BEGIN TO DEVELOP AS THE LAND MASS QUICKLY
WARMS WITH THE STEEP SUN ANGLE THIS TIME OF YEAR. THERE COULD BE A
FEW HEAVY DOWNPOURS ALONG THE COAST N OF BEAUFORT IF RECENT TRENDS
FROM THE RAP MODEL PAN OUT. CONVECTIVE TEMPS ARE PRETTY LOW TODAY
AND WE THINK SCATTERED CONVECTIVE RAINS WILL DEVELOP SOUTH ALONG
THE GEORGIA SEA BREEZE AND PROPAGATE W AND SW THIS AFTERNOON. 00Z
MODELS PROGS DIFFER ON THE AMOUNT OF INSTABILITY THIS AFTERNOON
BUT THE OPERATIONAL 13K RUC SHOWS DECENT POTENTIAL FOR SHORT-LIVED
BUT STRONG UPDRAFT POTENTIAL. OUR THINKING FOR SIGNIFICANT WEATHER
TODAY IS SIMILAR TO YESTERDAY/S REASONING...LOCALIZED DOWNPOURS
MORE LIKELY AND ONLY AN ISOLATED SEVERE WEATHER POTENTIAL AS BEST
MID LEVEL INSTABILITY AND LOW AND MID LEVEL LAPSE RATES LINGER W
OF THE AREA.
A COUPLE OF CHANGES WE MADE TO OUR FORECAST TODAY. WE RAISED POPS
TO 40-50 PERCENT IN THE CHARLESTON QUAD-COUNTY REGION AND RAISING
HIGH TEMPS OVER INLAND SE GEORGIA ZONES FURTHER INTO THE UPPER
80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
INLAND CONVECTIVE RAINS WILL BE ENDING EARLY IN THE EVENING AS
THE SEA BREEZE GETS WELL INLAND AND CONVERGENCE DIMINISHES. NO
CHANGES TO THE FORECAST TONIGHT WITH CLOUDS GRADUALLY THINNING
AND LOWS 65-70 DEGREES. WE MAY NEED TO EVENTUALLY ADD SOME PATCHY
FOG IN AGAIN TONIGHT...DEPENDENT ON TRENDS WITH CLOUD DISSIPATION.
A FAIRLY SIMILAR PATTERN WILL PERSIST WEDNESDAY INTO THURSDAY WITH
BROAD UPPER TROUGHING AND ATLANTIC HIGH PRESSURE. SOUTHERLY
LOW-LEVEL FLOW WILL MAINTAIN A FAIRLY MOIST ATMOSPHERE AND HELP PUSH
A SEABREEZE INLAND EACH DAY. THE UPPER TROUGHING WILL CREATE A
SOMEWHAT MORE FAVORABLE ENVIRONMENT FOR CONVECTION TO DEVELOP...
PRIMARILY DRIVEN BY THE SEABREEZE AND BOUNDARY INTERACTIONS. WE KEPT
POPS IN THE 20-30 PERCENT RANGE BOTH DAYS.
THE MODELS ARE NOW QUITE A BIT FASTER AND IN BETTER AGREEMENT
REGARDING A COLD FRONT PUSHING THROUGH FRIDAY MORNING. WE REMOVED
POPS ON FRIDAY AND SHOW DEWPOINTS DROPPING INTO THE UPPER 50S TO
AROUND 60 DURING THE AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THERE IS GOOD MODEL AGREEMENT THAT DRY CANADIAN HIGH PRESSURE WILL
EXPAND SOUTHEAST INTO THE FORECAST AREA OVER THE WEEKEND THEN SHIFT
OFFSHORE. DEWPOINTS LOOK TO DROP INTO THE LOWER 50S SATURDAY AND
SUNDAY...WHICH COMBINED WITH HIGHS IN THE LOWER 80S WILL RESULT IN
PLEASANT SPRING WEATHER. OVERNIGHT LOWS WILL PROBABLY DROP INTO THE
UPPER 50S IN SPOTS. LOW-LEVEL MOISTURE INCREASES EARLY NEXT WEEK AS
THE SURFACE HIGH SHIFTS OFFSHORE...BUT WE DID NOT SEE ANY STRONG
SYNOPTIC SCALE FEATURES TO WARRANT ADDING PRECIP.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
KCHS...THE MORNING IS LOOKING WETTER AND WETTER WITH EACH PASSING
HOUR THIS MORNING. PATCHY MVFR/IFR CIGS WILL LINGER THROUGH MID MORNING
OR UNTIL RAINS DIMINISH. ADDITIONAL RAINS ARE LIKELY WITH THE SEA
BREEZE THIS AFTERNOON BUT SHOULD EVENTUALLY DEVELOP W OF THE
TERMINAL BY LATER IN THE DAY. TONIGHT...MAINLY VFR BUT WILL WATCH
FOR LATE NIGHT LOW CLOUDS AND PATCHY FOG WITH WET SOILS AND LIGHT
WINDS.
KSAV...A FEW SHOWERS MAY DEVELOP WITH THE INITIATION OF THE SEA
BREEZE LATE MORNING OR EARLY AFTERNOON ALONG WITH BRIEF MORNING
MVFR CIGS POSSIBLE. BEST CHANCES FOR SHOWERS/TSTMS WILL BE WITH
AFTERNOON CONVECTION WHICH COULD BE MOVING SW ALONG OR JUST W OF
INTERSTATE 95. MAINLY VFR TONIGHT BUT THERE ARE CHANCES OF LATE
NIGHT MVFR/IFR CIGS AND POSSIBLY LIGHT FOG...ESPECIALLY IF SKIES
CLEAR.
EXTENDED AVIATION...SPORADIC REDUCTIONS IN CEILINGS/VSBYS MAINLY IN
AFTERNOON/EVENING SHOWERS OR STORMS THROUGH THURSDAY.
&&
.MARINE...
THROUGH TONIGHT...THE STEADY STATE SYNOPTIC PATTERN CONTINUES UNABATED.
OFFSHORE RIDGE OF HIGH PRESSURE EXTENDS W ACROSS THE COASTAL WATERS...
GENERATING SE AND S WINDS LESS THAN 15 KT AND SEAS IN THE 2-4 FOOT
RANGE...HIGHEST OVER OUTER GEORGIA WATERS BEYOND 20 NM.
HIGH PRESSURE WILL SIT OVER THE WESTERN ATLANTIC UNTIL FRIDAY WHEN A
CANADIAN HIGH DROPS SOUTHEAST. WE MAY SEE A BRIEF PERIOD OF SMALL
CRAFT ADVISORY CONDITIONS FRIDAY NIGHT INTO SATURDAY AS THE GRADIENT
TIGHTENS AND COLD ADVECTION MIXES SOME DECENT WINDS TO THE SURFACE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
AREA FORECAST DISCUSSION
NWS JACKSON KY
1026 AM EDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 1026 AM EDT TUE MAY 21 2013
THE FORECAST SOUNDINGS ARE FORECASTING EXTREME INSTABILITY TODAY. THE
NAM BUFFER SOUNDING FOR 4 PM AT JACKSON IS CALLING FOR TOTAL TOTALS
OF 51 AND A LIFTED INDEX OF -7.6. THE CAPE IS FORECAST TO BE 3479
JOULES. THE WIND IS NOT FAVORABLE FOR SEVERE THUNDERSTORMS AS THERE
IS VERY LITTLE SHEAR. THERE IS ALSO VERY LITTLE DRY AIR ALOFT. THE
MAIN ISSUE TODAY WILL BE A TRIGGER TO GET THE STORMS GOING. THERE IS
AN OLD OUTFLOW BOUNDARY CURRENTLY BISECTING EASTERN KENTUCKY FROM
NORTH TO SOUTH. BECAUSE IT IS SO EARLY IN THE DAY...THE LOW LEVEL
INSTABILITY IS CURRENTLY NOT FAVORABLE AND MOST LIKELY WILL NOT BE
FAVORABLE UNTIL THIS OUTFLOW BOUNDARY MOVES INTO WEST VIRGINIA. IT
MAY FIRE UP NEAR THE WEST VIRGINIA BORDER AROUND 11 AM. WILL HAVE TO
WAIT AND SEE. CURRENTLY DO NOT HAVE A GOOD FEEL ON EXACTLY WHERE AND
WHEN THE THUNDERSTORMS ARE GOING TO INITIATE. USED THE OUTPUT OF THE
HIGH RESOLUTION MODEL TO TRY AND TIME SOME IMPULSES THROUGH THE
AREA...HOWEVER CONFIDENCE IS FAIRLY LOW UNTIL CONVECTIVE INITIATION
ACTUALLY OCCURS. WITH ALL THE CONVECTION THAT HAS OCCURRED OUT TO THE
WEST...THERE ARE BOUND TO BE SOME OLD BOUNDARIES THAT MOVE THROUGH
THIS AFTERNOON. ALSO...WITH THE VALLEY FOG THAT OCCURRED THIS
MORNING...SOME DIFFERENTIAL HEATING BOUNDARIES MAY BE ABLE TO
GENERATE A STORM. ONCE THE STORMS ARE GENERATED...ANY OUTFLOWS THEY
PRODUCE SHOULD PROPAGATE ACROSS THE ENTIRE AREA. USUALLY WITH THIS
TYPE OF SOUNDING OVER THE AREA...THE THUNDERSTORMS PRODUCED WILL BE
PULSE TYPE STORMS. A FEW OF THESE STORMS MAY BECOME SEVERE AND
PRODUCE WIND GUSTS UP TO 60 MPH AND 1 INCH HAIL. DUE TO THE LACK OF
WIND SHEAR AND LACK OF ANY STRONG BOUNDARIES...TORNADOES ARE VERY
UNLIKELY TODAY AND WOULD PROBABLY NEED SOME INTERSECTING OUTFLOW
BOUNDARIES TO EVEN HAVE A PRAYER OF FORMING.
UPDATE ISSUED AT 759 AM EDT TUE MAY 21 2013
GRIDS WERE FRESHENED BASED ON RECENT OBS AND TO ACCOUNT FOR THE
OUTFLOW BOUNDARY AND CONVECTION WORKING EAST ACROSS CENTRAL KY THAT
LIKELY WILL NOT COMPLETELY DISSIPATE BEFORE REACHING EASTERN KY. THIS
LED TO SOME CHANGES IN POPS...GENERALLY TO RAISE THEM IN THE WEST
DURING THE AM...AND SLIGHTLY IN THE AFTERNOON ACROSS THE REMAINDER
OF THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PRE FIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 759 AM EDT TUE MAY 21 2013
ANY LINGERING VALLEY FOG WILL DISSIPATE THROUGH 1330Z. AN OUTFLOW
BOUNDARY WILL WORK INTO EASTERN KY DURING THE FIRST TWO HOURS OF THE
PERIOD...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO
AFFECT LOZ AND SME BY 15Z...AND POSSIBLY FURTHER EAST AT JKL AROUND
16Z. CONFIDENCE IN CONVECTIVE EVOLUTION THROUGH THE PERIOD IS NOT
EXTREMELY HIGH...BUT CONVECTION CANNOT BE RULED OUT DURING MUCH OF
THE PERIOD AND THUS VCTS AND CB WAS USED FOR MOST OF THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
804 AM EDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 759 AM EDT TUE MAY 21 2013
GRIDS WERE FRESHENED BASED ON RECENT OBS AND TO ACCOUNT FOR THE
OUTFLOW BOUNDARY AND CONVECTION WORKING EAST ACROSS CENTRAL KY THAT
LIKELY WILL NOT COMPLETELY DISSIPATE BEFORE REACHING EASTERN KY. THIS
LED TO SOME CHANGES IN POPS...GENERALLY TO RAISE THEM IN THE WEST
DURING THE AM...AND SLIGHTLY IN THE AFTERNOON ACROSS THE REMAINDER
OF THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OWB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PREFIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 759 AM EDT TUE MAY 21 2013
ANY LINGERING VALLEY FOG WILL DISSIAPTE THROUGH 1330Z. AN OUTFLOW
BOUNDARY WILL WORK INTO EASTERN KY DURING THE FIRST TWO HOURS OF THE
PERIOD...WITH ISOALTED TO SCATTERED SHOWERS AND THUNDERSTORMS TO
AFFECT LOZ AND SME BY 15Z...AND POSSIBLY FURTHER EAST AT JKL AROUND
16Z. CONFIDENCE IN CONVECTIVE EVOLUTION THROUGH THE PERIOD IS NOT
EXTREMELY HIGH...BUT CONVECTION CANNOT BE RULED OUT DURING MUCH OF
THE PERIOD AND THUS VCTS AND CB WAS USED FOR MOST OF THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1013 AM EDT TUE MAY 21 2013
.UPDATE...
SE MICHIGAN REMAINS LODGED WITHIN A DEEP/MOIST AND PROGRESSIVELY
DESTABILIZING SOUTHWEST FLOW LATE THIS MORNING. SEVERAL HOUR WINDOW
OF NEARLY FULL INSOLATION CERTAINLY HELPING THIS PROCESS...ALTHOUGH
THE NORTHERN EXTENSION OF THE REMNANT CLOUD DEBRIS ATTACHED TO THE
LEFTOVER WEAK PV FILAMENT STREAMING INTO WEST-CENTRAL OHIO WILL
BEGIN TO FILTERING THE HEATING COMPONENT SLIGHTLY HEADING INTO
MIDDAY. HOWEVER GIVEN CURRENT TRENDS...HIGH TEMPERATURES OF LOWER
TO MIDDLE 80S CERTAINLY ARE ATTAINABLE. THIS PROJECTS TO ROUGHLY
1500 J/KG OF MLCAPE FOR THIS AFTERNOON.
DESPITE THIS EMERGING LOW LEVEL INSTABILITY GRADIENT...DELINEATING
BOTH THE LOCATION AND SCALE OF CONVECTIVE DEVELOPMENT...BOTH
UPSTREAM AND LOCALLY...REMAINS A CHALLENGE FOR THE AFTERNOON AND
EVENING PERIOD. 12Z DTX SOUNDING AND RECENT MODEL GUIDANCE SUGGEST
SOME DEGREE OF CAPPING REMAINS IN PLACE...ALBEIT NOT NEARLY AS
STRONG AS NOTED YESTERDAY. CONVECTIVE INITIATION MAY BECOME TIED TO
ADDITIONAL WEAK SHORTWAVE ENERGY AND ON THE LEAD EDGE OF AN
EXPANDING DIFFERENTIAL HEATING ZONE WORKING ACROSS MISSOURI AND INTO
SOUTHERN ILLINOIS. RECENT HI RES MODEL GUIDANCE PROVIDE FEW
CLUES...SUGGESTING A WINDOW FOR ISOLATED/SCATTERED DISCRETE CELL
DEVELOPMENT IN THAT FAVORED 19-22Z PERIOD. GIVEN A SOLID BACKGROUND
THERMODYNAMIC ENVIRONMENT TO MAINTAIN UPDRAFT STRENGTH...THE
PRESENCE OF A SUPPORTIVELY DEEP LAYER WIND FIELD WILL MAINTAIN A
RISK OF DAMAGING WINDS AND HAIL WITH ANY CELLS THAT CAN ORGANIZE
THROUGH THE PEAK HEATING CYCLE.
MINOR UPDATE ISSUED ALREADY TO READJUST POPS THROUGH THE EVENING AND
TWEAK TEMPERATURES BASED ON RECENT TRENDS.
&&
.AVIATION...ISSUED 727 AM EDT TUE MAY 21 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 738 AM EDT TUE MAY 21 2013
UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......MR
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
738 AM EDT TUE MAY 21 2013
.UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
&&
.AVIATION...ISSUED 727 AM EDT TUE MAY 21 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......KURIMSKI
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
727 AM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
912 AM MDT TUE MAY 21 2013
.UPDATE...
LARGE UPPER LOW OVER THE EASTERN DAKOTAS WILL CONTINUE TO ROTATE
CLOUDS WESTWARD ACROSS EASTERN MONTANA TODAY. RAIN SHOWERS WILL
CONTINUE TO BE POSSIBLE MAINLY EAST OF A MILES CITY TO BROADUS
LINE TODAY BUT THESE WILL BE SHIFTING EAST BY LATE AFTERNOON.
EXPECT A MOSTLY SUNNY AND MILDER DAY TODAY FOR THE REMAINDER OF
THE FORECAST AREA. PATCHY FOG WILL CONTINUE FOR THIS MORNING FOR
THE LIVINGSTON AREA BUT THIS HAS BEEN BREAKING UP DURING THE PAST
HOUR. CURRENT FORECAST IN GOOD SHAPE WITH NO UPDATES PLANNED THIS
MORNING. HOOLEY
&&
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SOME LINGERING SHOWERS OVER KBHK SHOULD DISSIPATE BY THE EARLY
AFTERNOON. FOG IS SLOWLY LIFTING NEAR KLVM...BUT STILL MAY CAUSE
SOME IMPACTS...SO UPDATED THE KLVM TAF TO INCLUDE ONE MORE HOUR OF
LOWERED VISIBILITIES DUE TO FOG. THE REST OF THE AREA SHOULD
REMAIN UNDER VFR CONDITIONS TODAY...HOWEVER THERE IS A CHANCE FOR
AN ISOLATED SHOWER OR THUNDERSTORM...MOSTLY NEAR THE HIGHER
TERRAIN. SINGER
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/F 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
613 AM MDT TUE MAY 21 2013
.UPDATE...
WE HAVE UPDATED THE FORECAST TO INCLUDE PATCHY DENSE FOG FOR PARTS
OF SOUTH CENTRAL MT THIS MORNING. LIGHT WINDS AND A MOIST BOUNDARY
LAYER ARE CONTRIBUTING TO FOG AS OF 12 UTC...ESPECIALLY AROUND THE
LIVINGSTON AREA WHERE VISIBILITY HAS FALLEN TO LESS THAN A QUARTER
MILE. THE FOG SHOULD BURN OFF BY MID TO LATE MORNING ONCE THE LOW-
LEVELS WARM WITH SUNSHINE. SCHULTZ
&&
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SHOWERS WILL LINGER OVER THE EAST THIS MORNING AND TAPER OFF
THROUGH THE AFTERNOON. THE PRECIPITATION SHOULD STAY MAINLY EAST
OF KMLS AND IMPACT KBHK. FLYING CONDITIONS ARE EXPECTED TO REMAIN
VFR WITH ONLY ISOLATED MVFR CONDITIONS DEVELOPING IN HEAVIER
SHOWERS. THE REST OF THE AREA WILL HAVE A PARTLY CLOUDY SKY WITH
ONLY ISOLATED SHOWERS AND THUNDERSTORMS NEAREST THE MOUNTAINS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/F 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1020 AM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 1019 AM CDT TUE MAY 21 2013
FORECAST HAS BEEN UPDATED FOR WINDS THROUGH THE DAY. SURFACE LOW
CENTERED OVER EAST CENTRAL SOUTH DAKOTA THIS MORNING HAS ENHANCED
THE PRESSURE GRADIENT OVER NEBRASKA...WITH WINDS NOW BLOWING AT 20
TO 30 MPH WITH GUSTS UP TOWARDS 40 MPH IN PLACES. MODELS ARE
INDICATING WINDS WILL PEAK FROM NOW THROUGH AROUND 20Z...THEN AS
THE LOW SHIFTS EAST...THE STRONGER WINDS WILL SHIFT EASTWARD AS
WELL. AFTERNOON MIXING...WITH STRONG WINDS JUST ABOVE THE SURFACE
WILL KEEP THE WINDS UP THROUGH THE AFTERNOON...WITH A DECREASING
TREND THIS EVENING. THERE ARE A FEW SPOTS THAT HAVE BRIEFLY
REACHED WIND ADVISORY CRITERIA...BUT THINKING THIS WILL NOT BE
WIDESPREAD ENOUGH...OR WITH LONG ENOUGH DURATION AND WILL BE RIGHT
AT THE LOWER THRESHOLD FOR A WIND ADVISORY IF LOCATIONS DO HIT
ADVISORY CRITERIA WITH SUSTAINED AT 30 MPH AND GUSTS OVER 40 MPH.
OTHERWISE...TEMPERATURES ARE ON TREND...WITH HIGHS ONLY EXPECTED
IN THE UPPER 50S AND LOW 60S AS QUITE A BIT OF CLOUD COVER WILL BE
IN PLACE THROUGH THE DAY. ISOLATED TO SCATTERED LIGHT SHOWERS IN
THE FORECAST ARE ALSO ON TRACK AS THEY ROTATE AROUND THE LOW
PRESSURE SYSTEM. SO NO CHANGES IN THE PRECIPITATION FORECAST FOR
THE DAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 626 AM CDT TUE MAY 21 2013
MVFR CIGS SHOULD CONTINUE ALONG AND NORTH OF NEBRASKA HIGHWAY 2 TODAY
AND TONIGHT IN PERIODS OF LIGHT RAIN OR DRIZZLE. SOUTH OF HIGHWAY
2...GENERALLY VFR IS EXPECTED TODAY THROUGH TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BROOKS
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
628 AM CDT TUE MAY 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 626 AM CDT TUE MAY 21 2013
MVFR CIGS SHOULD CONTINUE ALONG AND NORTH OF NEBRASKA HIGHWAY 2 TODAY
AND TONIGHT IN PERIODS OF LIGHT RAIN OR DRIZZLE. SOUTH OF HIGHWAY
2...GENERALLY VFR IS EXPECTED TODAY THROUGH TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
739 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER
WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...A LARGE CLUSTER OF THUNDERSTORMS PRODUCING
HEAVY RAIN HAS DEVELOPED ACROSS THE SANDHILLS AND SOUTHERN PIEDMONT
OF NC. THIS CONVECTION IS DRIFTING SOUTHEASTWARD...PIVOTING AROUND
THE INLAND SIDE OF THE UPPER SHEAR AXIS THAT IS LINED UP ALONG THE
INTERSTATE 95 CORRIDOR. THE LATEST SEVERAL HRRR MODEL RUNS TAKE THIS
CONVECTION SOUTHEASTWARD INTO THE BENNETTSVILLE AND DARLINGTON AREA
OVER THE NEXT COUPLE OF HOURS...BUT DIVERGE FROM RUN TO RUN AS TO
WHAT HAPPENS LATER THIS MORNING. PRIOR RUNS SHOWED THE CONVECTION
CONTINUING TO RUN SOUTH/SOUTHEASTWARD THROUGH NOON...WHILE THE
LATEST RUN (08Z) DISSIPATES THE CURRENT CLUSTER WHILE DEVELOPING NEW
CONVECTION JUST INLAND FROM THE COAST BY LATE MORNING AHEAD OF THE
DEVELOPING SEABREEZE BOUNDARY.
THE TAKE-HOME MESSAGE FROM ALL THIS IS THAT WE HAVE AN AIRMASS THAT
REALLY WANTS TO PRODUCE CONVECTION GIVEN ANY POSSIBLE REASON.
CONVECTIVE OUTFLOW BOUNDARIES FROM THE CURRENT ACTIVITY PLUS THE
DEVELOPMENT OF A SEABREEZE THIS AFTERNOON SHOULD ENSURE THERE ARE
PLENTY OF REASONS FOR NEW CONVECTIVE DEVELOPMENT...THEREFORE I HAVE
RAISED POPS INTO THE LIKELY CATEGORY FOR MOST AREAS MORE THAN 20
MILES INLAND FROM THE COAST TODAY. WEST OF INTERSTATE 95 I HAVE
RAISED POPS INTO THE 70-90 PERCENT RANGE...ANTICIPATING THE CURRENT
SANDHILLS CONVECTION WILL SOAK THIS AREA IN THE NEXT FEW HOURS.
RAINFALL OVER THE PAST THREE DAYS HAS AVERAGED 2 TO 5 INCHES WEST OF
INTERSTATE 95 EXCEPT FOR THE WESTERN THIRD OF DARLINGTON COUNTY
WHERE BARELY ONE INCH HAS FALLEN. GIVEN SOME OF THE RADAR-ESTIMATED
TOTALS FROM ROCKINGHAM TO WEST OF CHERAW THIS MORNING IT IS POSSIBLE
FLOOD ADVISORIES OR WARNINGS MAY BE NEEDED IN MY PEE DEE COUNTIES IN
THE NEXT SEVERAL HOURS.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN THIS RECENT WET PERIOD
SEVERAL DAYS AGO HAS DEGENERATED INTO A 500-TO-700 MB SHEAR AXIS.
WIND SPEEDS SURROUNDING THE UPPER FEATURE ARE TOO WEAK AT THIS POINT
TO SUPPORT DYNAMIC LIFT...BUT RICH LOW AND MID LEVEL MOISTURE
REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS WITH PRECIPITABLE
WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY CONVECTIVE
CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY STEEPER THAN THE
MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S SEABREEZE BOUNDARY
SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION (NEARLY 10000
FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE PROCESSES WILL
DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS THIS AFTERNOON
SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...CURRENT RADAR IMAGERY SHOWS SCT SHOWERS/T-STORMS NEAR
AND WEST OF KFLO WITH MORE SHOWERS OFFSHORE. THERE ARE POCKETS OF
IFR CIGS WITHIN THE CWA...AND KFLO COULD DEVELOP IFR SHORTLY WITH
STORMS MOVING OVERHEAD. HAVE INCLUDED TEMPO -SHRA IN THE NEAR TERM
TO ACCOUNT FOR CURRENT ACTIVITY BASED ON RADAR TRENDS AND LATEST
HRRR RUNS. MORE SHOWERS/T-STORMS WILL DEVELOP TODAY WITH DAYTIME
HEATING. EXPECT VFR/MVFR TO PREVAIL WITH BRIEF PERIODS OF IFR IN
HEAVIER PCPN. BETTER PCPN CHCS WILL BE INLAND THIS AFTN...BUT SOME
SEA BREEZE STORMS COULD DRIFT BACK TOWARDS THE COAST AS WELL. S-SW
WINDS AOB 10 KTS THIS MORNING WILL BECOME SOUTH AROUND 10 KTS THIS
AFTN. MVFR/IFR CIGS/VSBYS ARE CERTAINLY POSSIBLE OVERNIGHT WITH THE
ABUNDANT LOW-LEVEL MOISTURE IN PLACE.
EXTENDED OUTLOOK...SLIGHT CHC OF SHOWERS WEDNESDAY. SHOWERS/T-STORMS
POSSIBLE THURSDAY THROUGH EARLY FRIDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE OVERALL SYNOPTIC
WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH PRESSURE HAS DROPPED
SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE NORTHERN PLAINS IS
STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS WILL ENSURE A SOUTH
WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH TONIGHT. SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE MOST NUMEROUS THIS
MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE CLEARING OUT MOST OF
THIS ACTIVITY FROM THE COASTAL WATERS THIS AFTERNOON. SEAS CURRENTLY
RANGE FROM 3-4 FT ON BUOYS IN THE CAPE FEAR VICINITY...IN A
COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6 SECOND SOUTHERLY
WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
720 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A TROUGH OVER THE REGION WILL GRADUALLY WEAKEN THROUGH WEDNESDAY. A
STRONG COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST LATE
THURSDAY... THEN PUSH THROUGH TO THE COAST BY FRIDAY MORNING. COOL
HIGH PRESSURE WILL FOLLOW THE FRONT LATE FRIDAY INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 315 AM TUESDAY...
DELAYED A BIT WITH DISCUSSION TO SEE THE LATEST EC MODEL SINCE
MODELS WERE AT ODDS ON TIMING/LOCATION OF CONVECTION CHANCES TODAY.
WATER VAPOR SATELLITE DATA INDICATED THE WEAKENING MID/UPPER TROUGH
STILL LINGERING OVER THE REGION. PRECIPITABLE WATER VALUES REMAIN
VERY HIGH (GENERALLY 1.5 TO 1.75 INCHES). AT THE SURFACE... A WEAK
TROUGH WAS LOCATED OVER THE EASTERN PIEDMONT WITH DEW POINT VALUES
IN THE UPPER 60S TO NEAR 70. ONLY SCATTERED SHOWERS WERE NOTED OVER
THE COASTAL PLAIN AT 06Z/21 MAY.
THE LATEST HI-RES MODELS... IN PARTICULAR THE HRRR (WHICH PREFORMED
WELL WITH THE CONVECTION ON MONDAY)... BUT INCLUDING THE NMM EAST
AND ARW EAST INDICATE SOME DEVELOPMENT OF CONVECTION WESTWARD
BETWEEN 09Z AND 12Z OVER THE SOUTHERN PIEDMONT AND SANDHILLS
REGION.... SPREADING NE ACROSS THE FAYETTEVILLE AND RALEIGH AREAS
AROUND RUSH HOUR THIS MORNING. INTERESTINGLY ENOUGH... THESE HI-RES
MODELS ALSO INDICATE THE TROUGH AND ASSOCIATED CONVECTION SETTLING
SOUTH INTO THE LOWER COASTAL PLAIN BY THIS AFTERNOON. THIS IS IN
STARK CONTRAST TO THE OPERATIONAL NAM/GFS WHICH BOTH DEPICT AN
UPTICK IN CONVECTION WITH AFTERNOON HEATING... AND LITTLE THIS
MORNING.
IN ADDITION... THE HI-RES MODELS ALSO SHOW THE CURRENT LINE OF
STORMS OVER WESTERN KY/TN SURGING TOWARD THE APPALACHIANS LATER
TODAY... THEN POSSIBLY CROSSING THE MOUNTAINS INTO THE PIEDMONT
BETWEEN 00Z-06Z/WED (TONIGHT).
NEEDLESS TO SAY... CONVECTION LOCATION AND TIMING IS DIFFICULT AT
BEST TO FORECAST BEYOND 6 HOURS... THEREFORE WE WILL USE THE LATEST
SATELLITE/RADAR TRENDS... ALONG WITH CURRENT DATA TO TRY TO PIN DOWN
THE FAVORED TIMING/LOCATION OF CONVECTION TODAY AND TONIGHT.
FOR NOW... SINCE THE HRRR PREFORMED WELL MONDAY WITH THIS TROUGH
OVERHEAD... WE WILL LEAN TOWARD SCATTERED CONVECTION THIS MORNING...
WITH ADDITIONAL SCATTERED CONVECTION MAINLY SOUTH AND EAST THIS
AFTERNOON. MORE ISOLATED STORMS EXPECTED TO THE NORTH AND WEST.
HIGHS WILL RETURN TO NORMAL WITH ADDITIONAL HEATING TODAY... LOWER
TO MID 80S.
TONIGHT... AT LEAST SOME CHANCE OF A LINE OF STORMS COMING OUT OF
THE BLUE RIDGE APPROACHING OR AROUND SUNSET. THE AIR MASS SHOULD
BECOME MORE UNSTABLE ESPECIALLY OVER THE WESTERN PIEDMONT DURING
THIS TIME. HOWEVER... MLCAPES OF LESS THAN 1500 J/KG SHOULD YIELD
SUB SEVERE CONVECTION ALONG AND EAST OF THE BLUE RIDGE TODAY OR
TONIGHT. LOW END CHANCE OF SHOWERS/STORMS INTO THE MIDNIGHT HOUR IN
THE WEST... OTHERWISE PARTLY CLOUDY. LOWS IN THE MID TO UPPER 60S.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 310 AM TUESDAY...
WEAK SHORTWAVE RIDGING OVER THE REGION WILL YIELD MOSTLY DRY AND
WARM WEATHER FOR ONE DAY (WED). HOWEVER...SUFFICIENT MOISTURE WILL
STILL BE IN PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR
1.5 INCHES OR SO. WIDELY SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS CAN BE EXPECTED. HIGHS SHOULD BE IN THE MID/UPPER
80S... WITH OVERNIGHT LOWS IN THE MID/UPPER 60S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...
UPPER LEVEL TROUGH WILL MOVE EASTWARD FROM THE MIDWEST ON
THURSDAY...WHICH WILL PUT THE AREA IN DEEP SOUTH TO SOUTHWESTERLY
FLOW DURING THE DAY. WITH MOISTURE IN PLACE AND SUFFICIENT
INSTABILITY... WITH MLCAPE VALUES OF 500 TO 1000 J/KG...
THUNDERSTORMS WILL DEVELOP DURING THE DAY. BULK SHEAR VALUES NEAR 25
KTS WILL SUPPORT THE DEVELOPMENT OF SOME MULTICELL CLUSTERS... AND
FEW STRONGER STORMS WITH GUSTY WINDS ARE POSSIBLE. NO WIDESPREAD
SEVERE WEATHER IS EXPECTED... AS THE BEST UPPER LEVEL FORCING
REMAINS NORTH OF THE AREA. HIGHS IN THE LOW TO MID 80S... LOWS IN
THE MID 60S.
THE ASSOCIATED COLD FRONT WILL PROGRESS INTO WESTERN NORTH CAROLINA
THURSDAY EVENING... REACHING THE COAST BY ABOUT 12Z FRIDAY. MIDLEVEL
DRYING WILL SPREAD ACROSS THE AREA FRIDAY... ENDING PRECIPITATION
AND DECREASING CLOUD COVER THROUGH THE DAY FROM WEST TO EAST. COLD
ADVECTION WILL TEMPER HIGHS... WHICH WILL BE IN THE MID 70S TO LOW
80S. COOLER LOWS IN THE MID 50S.
THE TROUGH MOVES OFF THE COAST EARLY SATURDAY... WITH AN UPPER LEVEL
RIDGE ACROSS THE MIDDLE OF THE COUNTRY AND THE SURFACE HIGH
POSITIONED WEST OF THE AREA... PUTTING THE REGION IN A NORTHWEST
FLOW REGIME THROUGH THE WEEKEND... AND KEEPING TEMPERATURES
SEVERAL DEGREES BELOW NORMAL THROUGH MONDAY... WITH HIGHS IN THE
UPPER 70S TO NEAR 80.. AND LOWS IN THE MID TO UPPER 50S.
&&
.AVIATION /12Z TUESDAY THROUGH FRIDAY/...
AS OF 715 AM TUESDAY...
24 HOUR TAF PERIOD:
LIFR AND IFR CEILINGS CONTINUE TO PREVAIL WITH MVFR TO VFR
VISIBILITIES AT ALL TERMINALS. CEILINGS SHOULD CONTINUE TO PREVAIL
FOR A FEW HOURS THIS MORNING BEFORE CONDITIONS GRADUALLY IMPROVE
LATE MORNING INTO EARLY AFTERNOON. VFR CONDITIONS EXPECTED THIS
AFTERNOON OUTSIDE OF SOME SCATTERED SHOWERS AND THUNDERSTORMS THAT
WILL BE POSSIBLE ONCE AGAIN. WINDS WILL CONTINUE TO BE LIGHT AND OUT
OF THE SOUTHWEST TODAY. LOWER CEILINGS AND VISIBILITIES ARE PROBABLE
AGAIN TONIGHT BETWEEN GENERALLY BETWEEN 9-13Z OR SO.
LONG TERM: SUB VFR CONDITIONS ARE POSSIBLE AGAIN WEDNESDAY AND
THURSDAY AS SHOWERS AND THUNDERSTORMS WILL CONTINUE OUT AHEAD OF AN
APPROACHING FRONTAL SYSTEM THAT WILL MOVE THROUGH THE AREA LATE
THURSDAY INTO EARLY FRIDAY. VFR CONDITIONS SHOULD RETURN FOR FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
653 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER
WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...A LARGE CLUSTER OF THUNDERSTORMS PRODUCING
HEAVY RAIN HAS DEVELOPED ACROSS THE SANDHILLS AND SOUTHERN PIEDMONT
OF NC. THIS CONVECTION IS DRIFTING SOUTHEASTWARD...PIVOTING AROUND
THE INLAND SIDE OF THE UPPER SHEAR AXIS THAT IS LINED UP ALONG THE
INTERSTATE 95 CORRIDOR. THE LATEST SEVERAL HRRR MODEL RUNS TAKE THIS
CONVECTION SOUTHEASTWARD INTO THE BENNETTSVILLE AND DARLINGTON AREA
OVER THE NEXT COUPLE OF HOURS...BUT DIVERGE FROM RUN TO RUN AS TO
WHAT HAPPENS LATER THIS MORNING. PRIOR RUNS SHOWED THE CONVECTION
CONTINUING TO RUN SOUTH/SOUTHEASTWARD THROUGH NOON...WHILE THE
LATEST RUN (08Z) DISSIPATES THE CURRENT CLUSTER WHILE DEVELOPING NEW
CONVECTION JUST INLAND FROM THE COAST BY LATE MORNING AHEAD OF THE
DEVELOPING SEABREEZE BOUNDARY.
THE TAKE-HOME MESSAGE FROM ALL THIS IS THAT WE HAVE AN AIRMASS THAT
REALLY WANTS TO PRODUCE CONVECTION GIVEN ANY POSSIBLE REASON.
CONVECTIVE OUTFLOW BOUNDARIES FROM THE CURRENT ACTIVITY PLUS THE
DEVELOPMENT OF A SEABREEZE THIS AFTERNOON SHOULD ENSURE THERE ARE
PLENTY OF REASONS FOR NEW CONVECTIVE DEVELOPMENT...THEREFORE I HAVE
RAISED POPS INTO THE LIKELY CATEGORY FOR MOST AREAS MORE THAN 20
MILES INLAND FROM THE COAST TODAY. WEST OF INTERSTATE 95 I HAVE
RAISED POPS INTO THE 70-90 PERCENT RANGE...ANTICIPATING THE CURRENT
SANDHILLS CONVECTION WILL SOAK THIS AREA IN THE NEXT FEW HOURS.
RAINFALL OVER THE PAST THREE DAYS HAS AVERAGED 2 TO 5 INCHES WEST OF
INTERSTATE 95 EXCEPT FOR THE WESTERN THIRD OF DARLINGTON COUNTY
WHERE BARELY ONE INCH HAS FALLEN. GIVEN SOME OF THE RADAR-ESTIMATED
TOTALS FROM ROCKINGHAM TO WEST OF CHERAW THIS MORNING IT IS POSSIBLE
FLOOD ADVISORIES OR WARNINGS MAY BE NEEDED IN MY PEE DEE COUNTIES IN
THE NEXT SEVERAL HOURS.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN THIS RECENT WET PERIOD
SEVERAL DAYS AGO HAS DEGENERATED INTO A 500-TO-700 MB SHEAR AXIS.
WIND SPEEDS SURROUNDING THE UPPER FEATURE ARE TOO WEAK AT THIS POINT
TO SUPPORT DYNAMIC LIFT...BUT RICH LOW AND MID LEVEL MOISTURE
REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS WITH PRECIPITABLE
WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY CONVECTIVE
CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY STEEPER THAN THE
MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S SEABREEZE BOUNDARY
SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION (NEARLY 10000
FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE PROCESSES WILL
DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS THIS AFTERNOON
SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...PLENTIFUL LOW-LEVEL MOISTURE HAS LED TO DEVELOPMENT OF
IFR STRATUS CEILINGS INLAND WHICH MAY CONTINUE THROUGH DAYBREAK. THE
ONLY POTENTIAL TO SCOUR OUT THESE LOW CIGS EARLIER WILL BE IF
CONVECTIVE SHOWERS OR T-STORMS CAN DEVELOP ACROSS THE SC PEE DEE
REGION AS SHOWN ON THE LATEST SEVERAL RUNS OF THE HRRR MODEL. THIS
COULD LEAD TO ENOUGH DISTURBANCE OF THE STABLE LOW-LEVEL INVERSION
TO LIFT CEILINGS AT KFLO TEMPORARILY INTO THE VFR RANGE SHORTLY
BEFORE DAYBREAK. ALONG THE COAST VFR CONDITIONS SHOULD PREVAIL
THROUGH DAYBREAK WITH THE POSSIBLE EXCEPTION OF SCATTERED SHOWERS
ADVECTING ONSHORE OFF THE ATLANTIC OCEAN...MAINLY AFTER 09Z...WITH
ACCOMPANYING MVFR CIGS.
AFTER DAYBREAK A TYPICAL SUMMER AIRMASS WILL YIELD SCATTERED SHOWERS
AND THUNDERSTORMS DURING THE HEAT OF THE DAY. PREVAILING SOUTH WINDS
SHOULD SWEEP MOST OF THE ACTIVITY AWAY FROM THE COAST BY
MID-AFTERNOON WITH FLO/LBT SEEING THE BEST POTENTIAL OF VSBY
RESTRICTIONS IN SHOWERS OR STORMS.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE OVERALL SYNOPTIC
WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH PRESSURE HAS DROPPED
SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE NORTHERN PLAINS IS
STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS WILL ENSURE A SOUTH
WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH TONIGHT. SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE MOST NUMEROUS THIS
MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE CLEARING OUT MOST OF
THIS ACTIVITY FROM THE COASTAL WATERS THIS AFTERNOON. SEAS CURRENTLY
RANGE FROM 3-4 FT ON BUOYS IN THE CAPE FEAR VICINITY...IN A
COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6 SECOND SOUTHERLY
WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...TRA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
922 AM EDT TUE MAY 21 2013
.SYNOPSIS...
THE AIR MASS WILL BECOME INCREASINGLY MOIST AND UNSTABLE THROUGH MID
WEEK AS AN AREA OF LOW PRESSURE OVER THE UPPER MIDWEST SLOWLY
APPROACHES THE REGION. THIS LOW PRESSURE SYSTEM WILL TRACK THROUGH
THE EASTERN GREAT LAKES LATE WEDNESDAY AND PUSH A COLD FRONT SOUTH
ACROSS THE AREA ON THURSDAY. HIGH PRESSURE WILL RETURN FOR THE END
OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AXIS OF WEAK LIFT MOVING EAST ACROSS THE CENTRAL PART OF THE CWA
ATTM. NEAR TERM MODELS GENERATE CONVECTION FROM THIS FEATURE OVER
THE SNOWBELT AREA BY 17Z WITH THE HRRR BY FAR THE MOST GENEROUS.
SINCE THE HRRR USUALLY TENDS TO BE OVERDONE WITH THIS TYPE OF
CONVECTION WILL ONLY RAMP UP A SLIGHT OR SMALL CHANCE POP FOR THIS.
OTHERWISE WILL GRADUALLY RAMP UP CHANCE POPS FOR SCT CONVECTION TO
DEVELOP DURING THE AFTERNOON BUT NOT SEEING THE COVERAGE AS
WIDESPREAD AS PREVIOUS THINKING. WILL INCREASE TEMPS OVER THE WEST
AND CENTRAL A LITTLE AS MID CLOUDS WILL BE ABSENT OVER THESE AREAS
FOR THE PEAK HEATING HOURS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
SOME LEFT OVER SHOWERS AND THUNDERSTORMS IN THE EVENING AND THEN
THE AREA SHOULD BE IN A LULL FOR MUCH OF TONIGHT AND THEN WAITING
FOR THE NEXT SYSTEM TO AFFECT THE REGION FOR WEDNESDAY INTO
WEDNESDAY NIGHT. THIS WILL BE THE DAY WITH THE BEST CHANCE OF
SEVERE WEATHER. THE COLD FRONT MOVES THROUGH ON THURSDAY. FRIDAY
SHOULD BE DRY AND COOL WITH HIGH PRESSURE BUILDING IN.
THE TEMPERATURE FORECAST IS TOUGH...ESPECIALLY THE HIGHS. IF THE
SHOWERS AND THUNDERSTORMS DEVELOP EARLY OR IF WE HAVE A LOT OF
DEBRIS CLOUDS THAT WILL AFFECT THE HIGHS. USED A BLEND OF GUIDANCE.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
MODELS IN DISAGREEMENT IN THE EXTENDED. GFS CONTINUES WITH CANADIAN
HIGH PRESSURE OVER THE ENTIRE AREA THROUGH THE WEEKEND. THE ECMWF
ON THE OTHER HAND HAS ANOTHER FRONT PUSH THROUGH THE AREA ON
SATURDAY...AND IS THUS WETTER AND COOLER. SINCE THE GFS HAS BEEN
CONSISTENT WITH THIS SOLUTION IGNORED THE ECMWF AND WENT WITH THE
GFS FORECAST. THIS WILL RESULT IN DRY NORTHERLY FLOW FOR THE AREA
FOR THE ENTIRE WEEKEND AND SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
PATCHY MVFR BR WILL END BY MID MORNING. MODELS CONTINUE TO
INDICATE SCATTERED TSRA FOR THIS AFTERNOON AS CAPES REACH 1000-1500
J/KG OVER AREA THIS AFTERNOON. CONFIDENCE IS LOW AS TO PRECISELY
WHERE AND WHEN THE TSRA WILL DEVELOP. MUCH BETTER CHANCE OF
ORGANIZED CONVECTION WEDNESDAY AFTERNOON.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS WEDNESDAY AND
THURSDAY.
&&
.MARINE...
SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON THE LAKE THROUGH MID WEEK.
MODELS HAVE BEEN CONSISTENT WITH THE NEXT SYSTEM MOVING ACROSS THE
LAKE ON THURSDAY. SMALL CRAFT ADVISORY WILL BE NEEDED AS NORTH TO
NORTHWEST WINDS INCREASE TO 15 TO 25 KNOTS IN COLDER AIR. THE 850MB
TEMPS DIP TO 2C BY THE WEEKEND. STRONG TO SEVERE STORMS APPEAR
POSSIBLE BOTH TODAY AND WEDNESDAY. BOATERS WILL NEED TO REMAIN
ALERT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA/ADAMS
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
912 AM EDT TUE MAY 21 2013
.SYNOPSIS...
THE AIR MASS WILL BECOME INCREASINGLY MOIST AND UNSTABLE THROUGH MID
WEEK AS AN AREA OF LOW PRESSURE OVER THE UPPER MIDWEST SLOWLY
APPROACHES THE REGION. THIS LOW PRESSURE SYSTEM WILL TRACK THROUGH
THE EASTERN GREAT LAKES LATE WEDNESDAY AND PUSH A COLD FRONT SOUTH
ACROSS THE AREA ON THURSDAY. HIGH PRESSURE WILL RETURN FOR THE END
OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PREVIOUS DISCUSSION...
AXIS OF WEAK LIFT MOVING EAST ACROSS THE CENTRAL PART OF THE CWA
ATTM. NEAR TERM MODELS GENERATE CONVECTION FROM THIS FEATURE OVER
THE SNOWBELT AREA BY 17Z WITH THE HRRR BY FAR THE MOST GENEROUS.
SINCE THE HRRR USUALLY TENDS TO BE OVERDONE WITH THIS TYPE OF
CONVECTION WILL ONLY RAMP UP A SLIGHT OR SMALL CHANCE POP FOR THIS.
OTHERWISE WILL GRADUALLY RAMP UP CHANCE POPS FOR SCT CONVECTION TO
DEVELOP DURING THE AFTERNOON BUT NOT SEEING THE COVERAGE AS
WIDESPREAD AS PREVIOUS THINKING. WILL INCREASE TEMPS OVER THE WEST
AND CENTRAL A LITTLE AS MID CLOUDS WILL BE ABSENT OVER THESE AREAS
FOR THE PEAK HEATING HOURS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
SOME LEFT OVER SHOWERS AND THUNDERSTORMS IN THE EVENING AND THEN
THE AREA SHOULD BE IN A LULL FOR MUCH OF TONIGHT AND THEN WAITING
FOR THE NEXT SYSTEM TO AFFECT THE REGION FOR WEDNESDAY INTO
WEDNESDAY NIGHT. THIS WILL BE THE DAY WITH THE BEST CHANCE OF
SEVERE WEATHER. THE COLD FRONT MOVES THROUGH ON THURSDAY. FRIDAY
SHOULD BE DRY AND COOL WITH HIGH PRESSURE BUILDING IN.
THE TEMPERATURE FORECAST IS TOUGH...ESPECIALLY THE HIGHS. IF THE
SHOWERS AND THUNDERSTORMS DEVELOP EARLY OR IF WE HAVE A LOT OF
DEBRIS CLOUDS THAT WILL AFFECT THE HIGHS. USED A BLEND OF GUIDANCE.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
MODELS IN DISAGREEMENT IN THE EXTENDED. GFS CONTINUES WITH CANADIAN
HIGH PRESSURE OVER THE ENTIRE AREA THROUGH THE WEEKEND. THE ECMWF
ON THE OTHER HAND HAS ANOTHER FRONT PUSH THROUGH THE AREA ON
SATURDAY...AND IS THUS WETTER AND COOLER. SINCE THE GFS HAS BEEN
CONSISTENT WITH THIS SOLUTION IGNORED THE ECMWF AND WENT WITH THE
GFS FORECAST. THIS WILL RESULT IN DRY NORTHERLY FLOW FOR THE AREA
FOR THE ENTIRE WEEKEND AND SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
PATCHY MVFR BR WILL END BY MID MORNING. MODELS CONTINUE TO
INDICATE SCATTERED TSRA FOR THIS AFTERNOON AS CAPES REACH 1000-1500
J/KG OVER AREA THIS AFTERNOON. CONFIDENCE IS LOW AS TO PRECISELY
WHERE AND WHEN THE TSRA WILL DEVELOP. MUCH BETTER CHANCE OF
ORGANIZED CONVECTION WEDNESDAY AFTERNOON.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS WEDNESDAY AND
THURSDAY.
&&
.MARINE...
SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON THE LAKE THROUGH MID WEEK.
MODELS HAVE BEEN CONSISTENT WITH THE NEXT SYSTEM MOVING ACROSS THE
LAKE ON THURSDAY. SMALL CRAFT ADVISORY WILL BE NEEDED AS NORTH TO
NORTHWEST WINDS INCREASE TO 15 TO 25 KNOTS IN COLDER AIR. THE 850MB
TEMPS DIP TO 2C BY THE WEEKEND. STRONG TO SEVERE STORMS APPEAR
POSSIBLE BOTH TODAY AND WEDNESDAY. BOATERS WILL NEED TO REMAIN
ALERT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA/ADAMS
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
715 AM CDT TUE MAY 21 2013
.MESOSCALE UPDATE...
CURRENT RADAR IMAGERY SHOWS THAT THE HRRR APPEARS TO BE WINNING
WITH ITS DEPICTION OF MULTIPLE ROUNDS OF STORMS MOVING ACROSS THE
MID STATE. INITIAL LINE OF STORMS CONTINUES TO COLLAPSE AS IT
MOVES EAST OF THE I-65 CORRIDOR...BUT A SECOND LINE IS APPROACHING
THE WESTERN CWA BORDER. A THIRD AND MUCH MORE INTENSE LINE OF
STORMS IS MOVING ACROSS EASTERN ARKANSAS TOWARDS THE MID STATE.
THUS APPEARS SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGHOUT
THE DAY AND EVENTUALLY SPREAD ACROSS THE ENTIRE CWA...AND HAVE
BUMPED UP POPS AND LOWERED HIGH TEMPS ACCORDINGLY. 12Z OHX
SOUNDING PRIOR TO THE INITIAL LINE OF STORMS HAD CONSIDERABLE
POTENTIAL INSTABILITY WITH AN LI OF -10 AND VERY STEEP LAPSE
RATES. THUS CANNOT RULE OUT SOME STRONG TO SEVERE STORMS WITH
THESE NEXT TWO LINES OF STORMS LATER THIS MORNING AND
AFTERNOON...WITH THE MAIN THREAT BEING DAMAGING WINDS.
SHAMBURGER
&&
.PREV DISCUSSION... /ISSUED 601 AM CDT TUE MAY 21 2013/
UPDATE...ADDED AVIATION SECTION FOR 12Z TAF`S.
AVIATION...LINE OF OVERNIGHT CONVECTION HAS STAYED TOGETHER AND
MOVED INTO MIDDLE TENNESSEE EARLY THIS MORNING, SO RAIN IS PART OF
THE INITIAL PERIOD OF THE TAF`S, ALONG WITH SOME FOG AT CSV. LOOK
FOR A REPRIEVE FROM THE WEATHER LATER THIS MORNING AND LASTING
THROUGH THE AFTERNOON, WITH A LONG STRETCH OF VFR WX. A COLD FRONT
APPROACHING FROM THE WEST WILL THEN BEGIN SPREADING ANOTHER ROUND
OF ACTIVE WEATHER ACROSS MIDDLE TENNESSEE THIS EVENING AND
OVERNIGHT, WITH THUNDERSTORMS POSSIBLE.
PREV DISCUSSION... /ISSUED 321 AM CDT TUE MAY 21 2013/
SHORT TERM...
RADAR IMAGERY THIS MORNING SHOWS AN EXTENSIVE LINE OF SHOWERS AND
THUNDERSTORMS FROM THE GREAT LAKES SOUTHWARD INTO WESTERN
TENNESSEE...WITH ACTIVITY NOW APPROACHING OUR WESTERN CWA BORDER.
ALTHOUGH MCS HAS SHOWN AN OVERALL WEAKENING TREND...SATELLITE
IMAGERY SHOWS NEW UPDRAFTS DEVELOPING ALONG LEADING EDGE OF COLD
POOL WITH CLOUD TOPS COOLING. LATEST SHORT TERM MODEL GUIDANCE
SUCH AS THE 4 KM WRF...HRRR...AND NSSL WRF ALL BRING ACTIVITY INTO
OUR WESTERN ZONES IN A FEW HOURS BEFORE DIMINISHING LATER THIS
MORNING...AND THUS WILL RAISE POPS SUBSTANTIALLY OVER GUIDANCE FOR
THE PRE-FIRST AND FIRST PERIOD OF THE FORECAST. ALSO BUMPED UP
CLOUD COVER AND WENT SIGNIFICANTLY BELOW MOS GUIDANCE HIGHS FOR
TODAY DUE TO ANTICIPATED CLOUDS/PRECIP. NO SEVERE WEATHER IS
EXPECTED WITH THESE STORMS THIS MORNING ALTHOUGH SOME GUSTY WINDS
MAY OCCUR. CHANGES TO THE FORECAST ARE LIKELY DEPENDING ON HOW
CURRENT ACTIVITY EVOLVES.
MODELS INDICATE A SHARP SHORTWAVE TROUGH CURRENTLY SEEN ON WATER
VAPOR IMAGERY OVER NEW MEXICO WILL SWING THROUGH THE SOUTHERN
PLAINS TODAY...THEN ACROSS THE OHIO VALLEY AND NORTHWEST PART OF
OUR FORECAST AREA TUESDAY NIGHT. EXPECTING NUMEROUS SHOWERS AND
THUNDERSTORMS TO DEVELOP TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON...THEN SPREAD INTO WESTERN TENNESSEE AND THE NORTHWEST
MID STATE TUESDAY EVENING AND ESPECIALLY AFTER MIDNIGHT TUESDAY
NIGHT. SPC HAS THE NORTHWEST PART OF THE FORECAST AREA IN A SLIGHT
RISK FOR SEVERE STORMS TUESDAY NIGHT...GENERALLY ALONG AND WEST OF
A LINE FROM WAYNESBORO TO SPRINGFIELD. APPEARS BEST CHANCE FOR ANY
SEVERE WEATHER IN OUR CWA WILL BE IN THE 03Z-12Z TIMEFRAME AS
SHORTWAVE TROUGH AXIS MOVES ACROSS...BUT NOCTURNAL TIMING MAY
REDUCE THE SEVERE POTENTIAL. FORECAST SOUNDINGS DO SHOW
SUBSTANTIAL MLCAPE AND MODERATE DEEP LAYER SHEAR TUESDAY
NIGHT...WHICH SUGGESTS POTENTIAL FOR A LOWER END THREAT OF SOME
DAMAGING WINDS OR LARGE HAIL. HOWEVER...ANY TORNADO THREAT
APPEARS VERY LOW IN OUR FORECAST AREA. MUCH BETTER CHANCES FOR
SEVERE STORMS WILL EXIST TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON/EVENING. NOTE THAT MUCH OF THE CWA EAST OF I-65 WILL
REMAIN DRY DURING THIS TIME PERIOD.
AS SHORTWAVE EXITS THE REGION ON WEDNESDAY...A COLD FRONT WILL
PUSH EASTWARD ACROSS THE MID STATE WITH ADDITIONAL SHOWERS AND
STORMS ANTICIPATED THROUGH THE DAY. ACTIVITY WILL END FROM WEST TO
EAST WEDNESDAY NIGHT AS MUCH COOLER AND DRIER AIR FILTERS IN.
BELOW NORMAL TEMPERATURES ARE THEN ANTICIPATED OVER THE WEEKEND
AS NORTHWEST FLOW BUILDS IN ALOFT...WITH LOWS IN THE 40S/50S AND
HIGHS IN THE 70S. MID STATE LOOKS TO STAY IN A NORTHWEST FLOW
PATTERN THROUGH THE REMAINDER OF THE FORECAST PERIOD WITH A
GRADUAL WARMING TREND...BUT MAJOR DIFFERENCES EXIST BETWEEN THE
GFS/ECMWF NEXT WEEK REGARDING PRECIP CHANCES WITH GFS COMPLETELY
DRY BUT ECMWF SHOWING DAILY POPS. HAVE TRENDED TOWARDS THE GFS
FOR NOW BUT NOTE THAT EXTENDED FORECAST IS LOW CONFIDENCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
541 AM CDT TUE MAY 21 2013
.MESOSCALE UPDATE...
RADAR INDICATES LINE OF THUNDERSTORMS CURRENTLY STRETCHES FROM
SPRINGFIELD TO LINDEN AND CONTINUES TO WEAKEN AS IT OUTRUNS WHAT
LITTLE INSTABILITY REMAINS. HOWEVER...LINE SHOULD REACH THE I-65
CORRIDOR AND NASHVILLE METRO AREA SOON WITH LIGHT TO MODERATE RAIN
AND A FEW LIGHTNING STRIKES EXPECTED. THE LINE SHOULD COLLAPSE AS
IT CONTINUES FURTHER EAST AND RUNS INTO THE UPPER LEVEL RIDGE IN
PLACE. MEANWHILE...TWO ADDITIONAL LINES OF STORMS ARE CURRENTLY
ONGOING ACROSS ARKANSAS...AND LATEST HRRR RUNS INDICATE THESE
STORMS MAY ALSO REACH THE MID STATE LATER THIS MORNING. VERY
UNCERTAIN ON IF THIS WILL OCCUR...BUT IF IT DOES POPS WOULD NEED
TO BE RAISED AND HIGH TEMPS LOWERED SUBSTANTIALLY DUE TO THE
CLOUD COVER/PRECIP. FOR NOW HAVE BUMPED UP POPS FOR THE WESTERN
TWO- THIRDS OF THE CWA FOR THE MORNING PERIOD...AND WILL TAKE A
WAIT AND SEE APPROACH ON THE ACTIVITY TO OUR WEST BEFORE CHANGING
GRIDS/ZONES FURTHER. SHOULD CONVECTION CONTINUE TO AFFECT THE MID
STATE THROUGHOUT THE DAY AS THE HRRR SUGGESTS...THIS WOULD LIKELY
REDUCE THE SEVERE WEATHER THREAT TUESDAY NIGHT.
SHAMBURGER
&&
.PREV DISCUSSION... /ISSUED 425 AM CDT TUE MAY 21 2013/
MESOSCALE UPDATE...
LINE OF THUNDERSTORMS HAS ENTERED STEWART COUNTY WITH WIND GUSTS
ALONG LEADING EDGE UP TO 50 MPH POSSIBLE PER HPX BASE VELOCITY
RADAR DATA. ALSO CANNOT RULE OUT SOME SMALL HAIL AS UPDRAFTS
REGENERATE ALONG THE FRONT SIDE OF COLD POOL AS LINE RACES
EASTWARD AT UP TO 60 MPH. SPC MESOANALYSIS SHOWS INSTABILITY AXIS
OF UP TO 1000 J/KG ACROSS NORTHWEST ZONES...DECREASING TO 500 J/KG
NEAR I-65 AND TO NEAR ZERO ON THE PLATEAU. THUS EXPECT LINE OF
STORMS TO CONTINUE GRADUALLY WEAKENING AS IT MOVES FURTHER
EASTWARD...BUT WILL CONTINUE TO CLOSELY MONITOR.
SHAMBURGER
PREV DISCUSSION... /ISSUED 321 AM CDT TUE MAY 21 2013/
SHORT TERM...
RADAR IMAGERY THIS MORNING SHOWS AN EXTENSIVE LINE OF SHOWERS AND
THUNDERSTORMS FROM THE GREAT LAKES SOUTHWARD INTO WESTERN
TENNESSEE...WITH ACTIVITY NOW APPROACHING OUR WESTERN CWA BORDER.
ALTHOUGH MCS HAS SHOWN AN OVERALL WEAKENING TREND...SATELLITE
IMAGERY SHOWS NEW UPDRAFTS DEVELOPING ALONG LEADING EDGE OF COLD
POOL WITH CLOUD TOPS COOLING. LATEST SHORT TERM MODEL GUIDANCE
SUCH AS THE 4 KM WRF...HRRR...AND NSSL WRF ALL BRING ACTIVITY INTO
OUR WESTERN ZONES IN A FEW HOURS BEFORE DIMINISHING LATER THIS
MORNING...AND THUS WILL RAISE POPS SUBSTANTIALLY OVER GUIDANCE FOR
THE PRE-FIRST AND FIRST PERIOD OF THE FORECAST. ALSO BUMPED UP
CLOUD COVER AND WENT SIGNIFICANTLY BELOW MOS GUIDANCE HIGHS FOR
TODAY DUE TO ANTICIPATED CLOUDS/PRECIP. NO SEVERE WEATHER IS
EXPECTED WITH THESE STORMS THIS MORNING ALTHOUGH SOME GUSTY WINDS
MAY OCCUR. CHANGES TO THE FORECAST ARE LIKELY DEPENDING ON HOW
CURRENT ACTIVITY EVOLVES.
MODELS INDICATE A SHARP SHORTWAVE TROUGH CURRENTLY SEEN ON WATER
VAPOR IMAGERY OVER NEW MEXICO WILL SWING THROUGH THE SOUTHERN
PLAINS TODAY...THEN ACROSS THE OHIO VALLEY AND NORTHWEST PART OF
OUR FORECAST AREA TUESDAY NIGHT. EXPECTING NUMEROUS SHOWERS AND
THUNDERSTORMS TO DEVELOP TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON...THEN SPREAD INTO WESTERN TENNESSEE AND THE NORTHWEST
MID STATE TUESDAY EVENING AND ESPECIALLY AFTER MIDNIGHT TUESDAY
NIGHT. SPC HAS THE NORTHWEST PART OF THE FORECAST AREA IN A SLIGHT
RISK FOR SEVERE STORMS TUESDAY NIGHT...GENERALLY ALONG AND WEST OF
A LINE FROM WAYNESBORO TO SPRINGFIELD. APPEARS BEST CHANCE FOR ANY
SEVERE WEATHER IN OUR CWA WILL BE IN THE 03Z-12Z TIMEFRAME AS
SHORTWAVE TROUGH AXIS MOVES ACROSS...BUT NOCTURNAL TIMING MAY
REDUCE THE SEVERE POTENTIAL. FORECAST SOUNDINGS DO SHOW
SUBSTANTIAL MLCAPE AND MODERATE DEEP LAYER SHEAR TUESDAY
NIGHT...WHICH SUGGESTS POTENTIAL FOR A LOWER END THREAT OF SOME
DAMAGING WINDS OR LARGE HAIL. HOWEVER...ANY TORNADO THREAT
APPEARS VERY LOW IN OUR FORECAST AREA. MUCH BETTER CHANCES FOR
SEVERE STORMS WILL EXIST TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON/EVENING. NOTE THAT MUCH OF THE CWA EAST OF I-65 WILL
REMAIN DRY DURING THIS TIME PERIOD.
AS SHORTWAVE EXITS THE REGION ON WEDNESDAY...A COLD FRONT WILL
PUSH EASTWARD ACROSS THE MID STATE WITH ADDITIONAL SHOWERS AND
STORMS ANTICIPATED THROUGH THE DAY. ACTIVITY WILL END FROM WEST TO
EAST WEDNESDAY NIGHT AS MUCH COOLER AND DRIER AIR FILTERS IN.
BELOW NORMAL TEMPERATURES ARE THEN ANTICIPATED OVER THE WEEKEND
AS NORTHWEST FLOW BUILDS IN ALOFT...WITH LOWS IN THE 40S/50S AND
HIGHS IN THE 70S. MID STATE LOOKS TO STAY IN A NORTHWEST FLOW
PATTERN THROUGH THE REMAINDER OF THE FORECAST PERIOD WITH A
GRADUAL WARMING TREND...BUT MAJOR DIFFERENCES EXIST BETWEEN THE
GFS/ECMWF NEXT WEEK REGARDING PRECIP CHANCES WITH GFS COMPLETELY
DRY BUT ECMWF SHOWING DAILY POPS. HAVE TRENDED TOWARDS THE GFS
FOR NOW BUT NOTE THAT EXTENDED FORECAST IS LOW CONFIDENCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1025 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM EDT TUESDAY...
NORTHWEST WINDS COMBINED WITH SUNSHINE WILL ALLOW VISIBILITIES TO
IMPROVE THIS MORNING...THUS THE DENSE FOG FOR WIDESPREAD HAS
ENDED. POCKET OF FOG MAY LINGER A HOUR OR SO IN THE DEEPER
SHELTERED LOCATION. SHORTWAVE OVER SOUTHSIDE THIS MORNING WILL
TRAVEL EAST INTO EASTERN VIRGINIA THIS AFTERNOON. RUC AND WRF
INDICATED THAT THE BEST CHANCE FOR THUNDERSTORMS THIS AFTERNOON
WILL BE ALONG THE SOUTHERN BLUE RIDGE. MADE SOME MINOR
ADJUSTMENTS IN TEMPERATURES AND DEW POINTS.
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
AS OF 730 AM EDT TUESDAY...
POCKETS OF FOG WILL CONTINUE TO LIFT THIS MORNING AS WINDS
INCREASE. LOW CLOUDS SHOULD LIFT BY LATE MORNING.
ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP AGAIN THIS
AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS TOO LOW TO INCLUDE IN
THE TAFS AT THIS TIME. FOG FORMATION OVERNIGHT WILL BE DEPENDENT
ON WHICH LOCATIONS GET RAIN THIS AFTERNOON AND WHICH CLEAR OUT
DURING THE EVENING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
736 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 730 AM EDT TUESDAY...
WIDESPREAD FOG COVERED THE REGION THIS MORNING WITH IFR TO LIFR
VISIBILITIES. LOW CONFIDENCE AS TO HOW FAST VISIBILITIES WILL
IMPROVE TO MVFR THEN VFR. ONCE 12Z RNK AND GSO UPPER AIR SOUNDINGS
ARE AVAILABLE...DEPTH OF LOW CLOUDS AND FOG WILL BE DETERMINED AND
EROSION TIME MAY BE EASIER TO JUDGE.
A SHORT WAVE OVER THE AREA TONIGHT MOVES INTO EASTERN
VIRGINIA THIS MORNING. ISOLATED TO SCATTERED THUNDERSTORMS WILL
DEVELOP AGAIN THIS AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS
TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. FOG FORMATION
OVERNIGHT WILL BE DEPENDENT ON WHICH LOCATIONS GET RAIN THIS
AFTERNOON AND WHICH CLEAR OUT DURING THE EVENING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ009-
012>020-022>024.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ001-002-
018.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS JACKSON KY
135 PM EDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 135 AM EDT TUE MAY 21 2013
THE AIR IS EXTREMELY UNSTABLE AND THE STORM PREDICTION CENTER JUST
UPDATED THEIR OUTLOOK AND PUT EASTERN KENTUCKY IN AN AREA OF SLIGHT
RISK FOR SEVERE THUNDERSTORMS. THE MAIN THREAT IS FOR STRONG
WINDS...HOWEVER HAIL CAN NOT BE TOTALLY RULED OUT AND WILL LIKELY SEE
SMALL HAIL IN THE AREA TODAY. WITH THE POTENTIALLY SEVERE STORMS IN
THE AREA...THE POSSIBILITY OF GUST FRONTS WELL OUT AHEAD OF THE
THUNDERSTORMS IS POSSIBLE AND COULD CREATE SOME UNEXPECTED STRONG
WINDS. CONFIDENCE IN THE TIMING OF CONVECTIVE EVOLUTION IS NOT
HIGH...AND WAS BASED ON A COMBINATION OF THE NAM AND HIGH RESOLUTION
RAPID REFRESH MODEL. DEPENDING ON HOW MUCH RAIN OCCURS...THERE MAY BE
A TIME OF POST FRONTAL MIST WHICH WOULD LAST A FEW HOURS AND THEN
IMPROVE. DUE TO LOW CONFIDENCE ON TIMING AND EXTENT OF THE
STORMS...THIS WAS NOT ADDED TO THE TAFS. ALSO EXPECTING TO SEE SOME
MIST AT THE TAF STATIONS AND VALLEY FOG IN THE VALLEYS AND NEAR AREAS
THAT GET A LOT OF PRECIPITATION TODAY.
.UPDATE...
ISSUED AT 1026 AM EDT TUE MAY 21 2013
THE FORECAST SOUNDINGS ARE FORECASTING EXTREME INSTABILITY TODAY. THE
NAM BUFFER SOUNDING FOR 4 PM AT JACKSON IS CALLING FOR TOTAL TOTALS
OF 51 AND A LIFTED INDEX OF -7.6. THE CAPE IS FORECAST TO BE 3479
JOULES. THE WIND IS NOT FAVORABLE FOR SEVERE THUNDERSTORMS AS THERE
IS VERY LITTLE SHEAR. THERE IS ALSO VERY LITTLE DRY AIR ALOFT. THE
MAIN ISSUE TODAY WILL BE A TRIGGER TO GET THE STORMS GOING. THERE IS
AN OLD OUTFLOW BOUNDARY CURRENTLY BISECTING EASTERN KENTUCKY FROM
NORTH TO SOUTH. BECAUSE IT IS SO EARLY IN THE DAY...THE LOW LEVEL
INSTABILITY IS CURRENTLY NOT FAVORABLE AND MOST LIKELY WILL NOT BE
FAVORABLE UNTIL THIS OUTFLOW BOUNDARY MOVES INTO WEST VIRGINIA. IT
MAY FIRE UP NEAR THE WEST VIRGINIA BORDER AROUND 11 AM. WILL HAVE TO
WAIT AND SEE. CURRENTLY DO NOT HAVE A GOOD FEEL ON EXACTLY WHERE AND
WHEN THE THUNDERSTORMS ARE GOING TO INITIATE. USED THE OUTPUT OF THE
HIGH RESOLUTION MODEL TO TRY AND TIME SOME IMPULSES THROUGH THE
AREA...HOWEVER CONFIDENCE IS FAIRLY LOW UNTIL CONVECTIVE INITIATION
ACTUALLY OCCURS. WITH ALL THE CONVECTION THAT HAS OCCURRED OUT TO THE
WEST...THERE ARE BOUND TO BE SOME OLD BOUNDARIES THAT MOVE THROUGH
THIS AFTERNOON. ALSO...WITH THE VALLEY FOG THAT OCCURRED THIS
MORNING...SOME DIFFERENTIAL HEATING BOUNDARIES MAY BE ABLE TO
GENERATE A STORM. ONCE THE STORMS ARE GENERATED...ANY OUTFLOWS THEY
PRODUCE SHOULD PROPAGATE ACROSS THE ENTIRE AREA. USUALLY WITH THIS
TYPE OF SOUNDING OVER THE AREA...THE THUNDERSTORMS PRODUCED WILL BE
PULSE TYPE STORMS. A FEW OF THESE STORMS MAY BECOME SEVERE AND
PRODUCE WIND GUSTS UP TO 60 MPH AND 1 INCH HAIL. DUE TO THE LACK OF
WIND SHEAR AND LACK OF ANY STRONG BOUNDARIES...TORNADOES ARE VERY
UNLIKELY TODAY AND WOULD PROBABLY NEED SOME INTERSECTING OUTFLOW
BOUNDARIES TO EVEN HAVE A PRAYER OF FORMING.
UPDATE ISSUED AT 759 AM EDT TUE MAY 21 2013
GRIDS WERE FRESHENED BASED ON RECENT OBS AND TO ACCOUNT FOR THE
OUTFLOW BOUNDARY AND CONVECTION WORKING EAST ACROSS CENTRAL KY THAT
LIKELY WILL NOT COMPLETELY DISSIPATE BEFORE REACHING EASTERN KY. THIS
LED TO SOME CHANGES IN POPS...GENERALLY TO RAISE THEM IN THE WEST
DURING THE AM...AND SLIGHTLY IN THE AFTERNOON ACROSS THE REMAINDER
OF THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PRE FIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 135 PM EDT TUE MAY 21 2013
THE AIR IS EXTREMELY UNSTABLE AND THE STORM PREDICTION CENTER JUST
UPDATED THEIR OUTLOOK AND PUT EASTERN KENTUCKY IN AN AREA OF SLIGHT
RISK FOR SEVERE THUNDERSTORMS. THE MAIN THREAT IS FOR STRONG
WINDS...HOWEVER HAIL CAN NOT BE TOTALLY RULED OUT AND WILL LIKELY SEE
SMALL HAIL IN THE AREA TODAY. WITH THE POTENTIALLY SEVERE STORMS IN
THE AREA...THE POSSIBILITY OF GUST FRONTS WELL OUT AHEAD OF THE
THUNDERSTORMS IS POSSIBLE AND COULD CREATE SOME STRONG LLWS. CONFIDENCE
IN THE TIMING OF CONVECTIVE EVOLUTION IS NOT HIGH...AND WAS BASED ON
A COMBINATION OF THE NAM AND HIGH RESOLUTION RAPID REFRESH MODEL.
DEPENDING ON HOW MUCH RAIN OCCURS...THERE MAY BE A TIME OF POST
FRONTAL MIST WHICH WOULD LAST A FEW HOURS AND THEN IMPROVE. DUE TO
LOW CONFIDENCE ON TIMING AND EXTENT OF THE STORMS...THIS WAS NOT
ADDED TO THE TAFS. ALSO EXPECTING TO SEE SOME MIST AT THE TAF
STATIONS AND VALLEY FOG IN THE VALLEYS AND NEAR AREAS THAT GET A LOT
OF PRECIPITATION TODAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS CARIBOU ME
645 PM EDT TUE MAY 21 2013
.SYNOPSIS...
A FRONTAL BOUNDARY WILL REMAIN ALONG THE SOUTHERN PART OF OUR
REGION THROUGH MID WEEK. SMALL WAVES OF LOW PRESSURE WILL TRACK
ALONG THIS BOUNDARY TODAY AND WEDNESDAY. A LARGER STORM SYSTEM
FROM THE MIDWEST WILL TRACK TO OUR WEST ON THURSDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
645 PM UPDATE: ADJUSTED THE POPS TO ADVERTISE RAIN COMING INTO THE
WRN AREAS EARLIER THAN PREVIOUSLY FCST USING THE LATEST RADAR AND
HRRR. RAFL AFTER MIDNIGHT IN THE WEST-CENTRAL AREAS COULD BE HEAVY
AT TIMES AS RUC SHOWS NICE 5OKT JETLET AT 700 MBS OVERRUNNING THE
WARM FRONT. DECENT LLVL CONVERGENCE IN PLACE AS WELL. THEREFORE,
QPF WAS ADJUSTED USING THE LATEST NERFC GRIDS WHICH SHOWS UP TO
.75" FROM 06-12Z WEDNESDAY IN THE AFOREMENTIONED AREAS. TWEAKED
TEMPERATURES USING THE LATEST LAMP WHICH POINTS TO TEMPERATURES
WARMER THAN PREVIOUSLY FCST.
THE FA WILL ENJOY A BRIEF BREAK IN THE ACTION ERLY THIS EVE
BEFORE CLDNSS FROM ANOTHER S/WV...OLD CNVCTV COMPLEX MOVE W TO E
INTO THE FA DURG THE OVRNGT HRS AS A SFC WARM FRONT REMAINS
STATIONARY OVR THE GULF OF ME. BLENDED 6 HRLY RNFL AMOUNTS LOOK TO
BE MORE SIG AND WIDESPREAD THAN THE AREA OF SHWRS THAT CROSSED THE
REGION EARLIER TDY. IN ADDITION...THERE MAY BE HEAVIER DOWNPOURS
AS MORE CNVCTV ELEMENTS MOVE INTO E CNTRL AND DOWNEAST PTNS OF THE
FA WITH A WEAK ELEVATED CAPE ENVIRONMENT. THIS IDEA IS SUPPORTED
BY CURRENT LGTNG STRIKES ON THE S SIDE OF THE COMPLEX AS IT MOVES
E THRU ERN ONT TOWARD SW QB...SO WE DID INCLUDE ISOLD TSTMS VERY
LATE TNGT OVR CNTRL AND DOWNEAST AREAS. WITH THIS IN MIND...SOME
LOCATIONS OVR THESE PTNS OF THE FA COULD RECEIVE ARND AN INCH OR
EVEN A LITTLE MORE OF TOTAL QPF...WITH ARND A HLF INCH OR SO OVR
THE N...ENOUGH TO JUSTIFY NEAR 100 PERCENT POPS FOR VIRTUALLY ALL
OF THE FA BY WED MORN. LASTLY...WITH LOW TO MID LVL WARM ADVCN
WHICH WILL INCLUDE A MARINE COMPONENT OF AIRFLOW WILL RESULT IN
PATCHY FOG ACROSS THE N VERY LATE TNGT AND AREAS OF FOG S WHICH
WILL LIKELY CARRY OVER WELL INTO THE MORN HRS.
MOST OF THE STEADY RN SHOULD TAPER OFF TO LIGHTER SHWRS WED AFTN
AS THE S/WV MOVES E OF THE FA. LOW TEMPS WILL BE MILD AGAIN AS
CLDNSS...RNFL AND FOG LATE TNGT KEEP TEMPS FROM FALLING MUCH.
HI TEMPS WED WILL BE MUCH SUPPRESSED DUE TO LLVL DAMMING OF RAIN
COOLED AIR HANGING IN ACROSS THE FA THRU THE DAY.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AN UPPER LEVEL TROF ACROSS THE WESTERN GREAT LAKES AT THE START OF
THE PERIOD WILL SLOWLY MIGRATE EAST WEDNESDAY NIGHT THROUGH
THURSDAY. MEANWHILE AT THE SURFACE...LOW PRESSURE WILL TRACK
NORTHEAST ACROSS THE GREAT LAKES AND THROUGH QUEBEC...PASSING TO
NORTH OF THE STATE LATE THURSDAY. A COLD FRONT ASSOCIATED WITH THIS
SYSTEM WILL SLOWLY APPROACH FROM THE WEST LATER THURSDAY. THE FRONT
WILL SLOW DOWN AS IT BECOMES PARALLEL TO THE UPPER FLOW WITH A BROAD
SOUTHWEST FLOW IN PLACE.
A CHANCE OF SHOWERS WILL EXIST WEDNESDAY NIGHT AS A WARM FRONT LIFTS
NORTH ACROSS THE REGION. THE CHANCE OF SHOWERS WILL INCREASE DURING
THE DAY THURSDAY IN ADVANCE OF THE SLOW MOVING COLD FRONT
APPROACHING FROM THE WEST. THERE WILL ALSO BE THE CHANCE FOR
THUNDERSTORMS DURING THURSDAY AFTERNOON ESPECIALLY ACROSS WESTERN
AREAS WHERE SB CAPES INCREASE TO 500-1000 J/KG PER GFS. THERE IS
SOME 0-6KM SHEAR AS WELL SO POTENTIAL IS THERE FOR SOME ORGANIZED
THUNDERSTORMS TO DEVELOP. OF COURSE...THIS WILL BE DEPENDENT ON JUST
HOW MUCH INSTABILITY DEVELOPS IN ADVANCE OF THE FRONT. THINKING WE
WILL SOME BREAKS OF SUNSHINE ACROSS WESTERN AREAS AWAY FROM THE
COAST AS LOW LEVEL FLOW BECOMES SOMEWHAT MORE SOUTHWEST. FOR
NOW...HAVE CONFINED MENTION OF THUNDER TO WESTERN AND NORTHERN
AREAS THURSDAY WITH MARINE INFLUENCE KEEPING THINGS MORE STABLE
DOWNEAST. WITH THE POTENTIAL FOR BREAKS ON THURSDAY AND 925 MB
TEMPERATURES AROUND +17C HAVE HAVE LEANED WITH WARMER MAV NOS FOR
MAXS THURSDAY.
SHOWERY TYPE WEATHER AND PERHAPS SOME LINGERING THUNDER CAN BE
EXPECTED INTO THURSDAY EVENING BEFORE TRANSITIONING TO A MORE STEADY
RAIN THURSDAY NIGHT IN RESPONSE TO AN AREA OF LOW PRESSURE
DEVELOPING TO OUR SOUTH ALONG THE SLOW MOVING FRONTAL BOUNDARY. A
STEAD RAIN IS EXPECTED TO CONTINUE ON FRIDAY AS LOW PRESSURE MOVES
NORTHEAST ALONG THE NEARLY STATIONARY FRONTAL BOUNDARY ACROSS THE
AREA. LOOK LIKE MOST AREAS WILL SEE ANYWHERE FROM A QUARTER TO HALF
AN INCH OF RAINFALL ON FRIDAY. BLENDED SREF/GFS FOR RAINFALL
AMOUNTS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
DAMP AND UNSETTLED WEATHER PTRN LOOKS TO CONT INTO THE LONGER
TERM... LONG RANGE GUIDANCE IN REASONABLE AGREEMENT W/ THE OPNL 12Z
GFS AND 00Z ECMWF SHOWING A NRLY STALLED FRONTAL BNDRY OVR EXTRA
SERN MAINE AT 00Z SAT. BOTH MODELS ADVERTISE BROAD AREA OF LOW
PRES FROM S OF SRN NEW ENGLAND UP INTO NB. BY 12Z SAT THE GFS HAS
DVLP A FAIRLY SIGNIFICANT CLOSED SFC LOW PRES SYSTEM NR CAPE COD
WHILE THE ECMWF IS FURTHER NEWRD W/ THIS LOW OVR WRN NS... BY 00Z
SUN...THE GFS HAS MOVD THIS DEEPENING SYSTEM NEWRD INTO SERN MAINE
WHILE THE ECMWF HAS THE SYSTEM OVR XTRM NERN NB. THEREAFTER THE
GFS WRAPS THIS LOW INTO NRN MAINE WHILE THE ECMWF LIFTS IT NEWRD
TO THE MOUTH OF THE ST LAWRENCE BY 12Z SUN. DESPITE THE 12
TIMING DIFFS...BOTH MODELS SUGGEST A POTENTIALLY SIGNIFICANT QPF
EVENT FOR THE PD LATER FRI NGT INTO SAT NGT W/ CHILLY AND
UNSETTLED CONDS PERSISTING THRU SUN.
STILL BRISK AND CHILLY INTO MON W/ A CONTG CHC OF SOME SHOWERS
SPCLY N AND W THEN APPEARS SOME DRIER AND MILDER AIR MAY FINALLY
WORK INTO THE FA BY TUE. ATTM...NOT THE BEST LOOKING MEMORIAL DAY
WEEKEND WX WISE FOR OUR REGION...
WILL CARRY LIKELY TO CAT POPS FRI NGT INTO SAT NGT W/ THE HIGHEST
POPS E AND SE. PLAYED TEMPS ON THE COOL SIDE USING A CONS ALL
BLEND...
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: VFR NRN TAF SITES THIS EVENING WHILE DOWNEAST SITES
HOLD IFR OR IMPROVE TO MVFR. ALL SITES THEN LOWERING TO IFR TO
LIFR LATE TNGT INTO ERLY WED MORN WITH ANOTHER ROUND OF LOW CLDNSS
SHWRS AND PATCHY TO AREAS OF FOG. LIFR CONDITIONS WED MORN ONLY
IMPROVE TO IFR WED AFTN AS STEADY MORN RN AND FOG TAPERS TO AFTN
SHWRS.
SHORT TERM: MVFR/IFR CONDITIONS ARE EXPECTED WEDNESDAY NIGHT AND
INTO THURSDAY MORNING IN LOW CLOUDS AND SHOWERS. CONDITIONS
SHOULD IMPROVE TO MVFR/VFR LATER THURSDAY MORNING INTO THURSDAY
AFTERNOON. SHOWERS ARE EXPECTED TO INCREASE ACROSS THE REGION
LATER THURSDAY AFTERNOON AND COULD EVEN SEE SOME SCT TSRA NORTHERN
TERMINALS THURSDAY AFTERNOON. MVFR/IFR CAN BE EXPECTED ON FRIDAY
IN STEADY RAIN.
&&
.MARINE...
NEAR TERM: NO HDLNS XPCTD OVRNGT THRU WED. WV HTS WILL HAVE SOME
SWELL COMPONENT OVR THE OUTER WATERS...REACHING UP TO 4 FT AT TMS.
WE USED A BLEND OF WW3 AND SWAN GFS...SMOOTHED 10 TMS OVR IN THE
VCNTY OF THE COAST TO LOWER WV HTS FOR THE INNER BAY/HARBOR MZ.
SHORT TERM: WINDS/SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS
WEDNESDAY NIGHT. WINDS/SEAS WILL INCREASE THURSDAY AND CONTINUE
TO INCREASE TO SMALL CRAFT ADVISORY LEVELS THURSDAY NIGHT AND
FRIDAY. AREAS OF FOG WILL LIKELY REDUCE VISIBILITY TO 1 TO 3 NM
ESPECIALLY THURSDAY NIGHT AND ON FRIDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT/VJN
SHORT TERM...DUDA
LONG TERM...KHW
AVIATION...HEWITT/VJN/DUDA
MARINE...HEWITT/VJN/DUDA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
358 PM EDT TUE MAY 21 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 357 PM EDT TUE MAY 21 2013
12Z ROABS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SLOW MOVING UPR LO
OVER ERN SDAKOTA BTWN UPR RDG OVER SCENTRAL CANADA AND A RIDGE OFF
THE SE CONUS. BAND OF SHRA/SCT TS THAT IMPACTED THE CWA EARLIER HAS
LIFTED TO THE N ALONG WITH RESPONSIBLE SHRTWV...ALLOWING FOR MAINLY
DRY WX OVER UPR MI EARLY THIS AFTN. BUT SINCE THE CWA IS N OF SFC
WARM FNT IN WI...PLENTY OF LO CLDS LINGER. THERE IS ALSO SOME FOG...
MAINLY NEAR THE COOLER GREAT LKS. ANOTHER DISTURBANCE IS ROTATING N
THRU IOWA ARND THE CLOSED LO. THE APRCH OF THIS DISTURBANCE HAS
RESULTED IN SOME SHRA OVER CENTRAL WI WHERE BREAKS IN THE LO CLDS
ALONG AND S OF WARM FNT HAVE LIFTED SB CAPE 500-1000 J/KG PER SPC
MESOANALYSIS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE SHRA/TS TRENDS ASSOCIATED
WITH SHRTWV IN IOWA AND THEN APRCH OF MAIN UPR LO.
LATE THIS AFTN/TNGT...SHORT RANGE MODELS ARE IN FAIRLY GOOD
AGREEMENT SHOWING SHRA NOW OVER CENTRAL WI DRIFTING ACRS THE WI
BORDER BY 21Z AND THEN CONTINUING TO THE NE. RUC FCST SDNGS MODIFIED
FOR TEMP/DEWPT OF 68/58 YIELDS SBCAPE UP TO 750 J/KG...SO ADDED
MENTION OF TS. RELATIVELY WEAK WINDS SFC-H5 AS WELL AS DEEP
MSTR/SKINNY CAPE WITH PERSISTENT LO CLDS LIMITING DIURNAL HEATING
INDICATE A LO RISK FOR ANY SVR TS...BUT ANY SHRA COULD RESULT IN
SOME HEAVY RA WITH FCST KINX AS HI AS THE UPR 30S. ONCE THE SHRA
MOVE FARTHER TO THE NE AND AWAY FM THE SFC HEATING AREA...ONE MIGHT
EXPECT THESE SHRA TO DIMINISH THRU THE NGT. BUT FCST AREA OF H85-7
FGEN N OF WARM FNT MIGHT ACT TO SUSTAIN THESE SHRA. WL GO WITH HI
CHC-LIKELY POPS THIS EVNG NEAR THE WI BORDER DIMINISHING TO CHCY
POPS TO THE NE. SINCE THE LLVL FLOW IS FCST TO BACK MORE TO THE NE
FOLLOWING THE PASSAGE OF THIS SHRA AREA...EXPECT COOLER LAKE
AIR/SOME FOG TO MOVE BACK INTO THE AREA OVERNGT.
WED...AS CLOSED LO TO THE W BEGINS TO SHIFT FASTER TO THE ESE TO SW
WI BY 00Z THU...AREA OF LARGER SCALE QVECTOR CNVGC WL IMPACT MAINLY
THE AREA NEAR THE WI BORDER BUT WEAKEN WITH TIME AS THE UPR CLO
BEGINS TO OPEN. BAND OF RA ACCOMPANYING AXIS OF SHARPER FGEN OVER
WRN LK SUP/THE WRN ZNS SHOULD THUS SHIFT SLOWLY TO THE SE THRU THE
DAY. ARRIVAL OF DRIER AIR FM THE NW TO THE SE OF EXPANDING HI PRES
OVER SCENTRAL CANADA MIGHT START TO DIMINISH THE PCPN OVER THE FAR W
LATER IN THE DAY. OTRW...LOWERED FCST HI TEMPS TO ACCOUNT FOR STEADY
NE WIND OFF LK SUP AND EXPECTED CLD COVER.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 357 PM EDT TUE MAY 21 2013
AFTER A WET START TO THE WEEK...THE LONG TERM PERIOD LOOKS TO BE
FAIRLY DRY AS CANADIAN HIGH PRESSURE SLIDES THROUGH THE UPPER GREAT
LAKES REGION.
FIRST...THE UPPER TROUGH THAT HAS BEEN INFLUENCING THE WEATHER FOR
THE START OF THE WORK WEEK WILL BE SITUATED OVER WISCONSIN AND IOWA
AND SHIFTING EAST THROUGH THE GREAT LAKES REGION ON WEDNESDAY
NIGHT. MEANWHILE...THE SURFACE LOW WILL BE LOCATED OVER LOWER
MICHIGAN AT 00Z THURSDAY AND BEGIN TO MOVE UP THE ST LAWRENCE
SEAWAY WEDNESDAY NIGHT INTO THURSDAY AS A SHORTWAVE INTENSIFIES THE
LOW. AS THIS OCCURS...HIGH PRESSURE ORIGINATING FROM NORTH CENTRAL
CANADA WILL BE MOVING A RIDGE INTO THE UPPER MISSISSIPPI VALLEY ON
WEDNESDAY NIGHT AND THE UPPER GREAT LAKES ON THURSDAY. WITH THE
UPPER TROUGH AND CLOSE PROXIMITY OF THE LOW...THERE WILL STILL BE
DEEPER MOISTURE AND 850-700MB Q-VECTOR CONVERGENCE OVER THE
SOUTHEAST HALF OF THE CWA. IN ADDITION...WITH THE INCREASING
NORTHERLY 850-700MB FLOW OVER THE AREA MODELS ARE CONSISTENT ON AN
AREA OF FGEN SETUP FROM IRONWOOD THROUGH EASTERN LAKE SUPERIOR AT
00Z THURSDAY. THEN AS THE LOW SHIFTS EAST...THE FGEN WILL SLIDE
SOUTHEAST THROUGH THE NIGHT AND LIKELY EXIT THE MOST IF NOT ALL OF
THE CWA BY 12Z THURSDAY. AT THIS POINT...THINKING THAT THE MOVEMENT
OF THE PRECIPITATION SHOULD KEEP AMOUNTS UNDER A QUARTER OF AN
INCH.
CANADIAN HIGH PRESSURE THEN BECOMES THE DOMINATING FEATURE FOR THE
REST OF THE PERIOD...AS THE AREA IS UNDER NORTHWEST FLOW ALOFT.
THIS DRY CANADIAN AIR AND COOLER NORTHERLY LOW LEVEL WINDS WILL
LEAD TO NICE BUT SLIGHTLY COOLER THAN NORMAL START TO THE MEMORIAL
DAY WEEKEND. THE STRONGEST NORTHERLY FLOW OFF LAKE SUPERIOR WILL BE
ON THURSDAY WITH THE CLOSER PROXIMITY OF THE EXITING LOW. THIS WILL
KEEP TEMPERATURES COOLER THAN MOST OF THE DAYS...WITH HIGHS IN THE
UPPER 40S NEAR LAKE SUPERIOR AND IN THE 50S INLAND. FRIDAY-SUNDAY
WILL BE DOMINATED BY LAKE BREEZES EACH DAY...WITH THE WARMEST
TEMPERATURES OVER THE INTERIOR LOCATIONS /60S/. THERE ARE HINTS OF A
COUPLE WEAK SHORTWAVES MOVING THROUGH THE NORTHWEST FLOW ALOFT
FRI-SUN...BUT WILL THE DRY AIR IN PLACE...WOULDN/T EXPECT MUCH FOR
PRECIPITATION CHANCES. UNDER THE HIGH PRESSURE RIDGE ON THURSDAY
NIGHT...EXPECT TO SEE SOME SUB FREEZING LOWS OVER THE INTERIOR
PORTIONS OF UPPER MICHIGAN. PWAT VALUES AROUND 40 PERCENT OF NORMAL
AND LIGHT WINDS WOULD BE FAVORABLE WELL BELOW NORMAL LOWS. MAV/MET
GUIDANCE PICKING UP ON THIS IDEA WITH LOWS BETWEEN 25-30 OVER THE
WEST AND THAT SEEMS FAIRLY REASONABLE. HAVE TRENDED THAT DIRECTION
AND LOWERED TEMPS OVER THE WEST AROUND 5 DEGREES. FROST/FREEZE
HEADLINES DON/T START UNTIL MEMORIAL DAY...SO THERE WON/T BE ANY
HEADLINES...BUT ANYONE THAT HAS PLANTED EARLY WILL NEED TO PREPARE
FOR A POTENTIAL FROST/FREEZE.
UPPER RIDGING THAT WILL BE NEARLY STATIONARY JUST EAST OF THE
NORTHERN ROCKIES DURING THIS PERIOD WILL BEGIN TO SHIFT EAST ON
SUNDAY NIGHT AS THE UPPER TROUGH OVER THE NEW ENGLAND STATES SHIFTS
EAST INTO THE ATLANTIC. THIS WILL START A GRADUAL WARMING TREND
TOWARDS MEMORIAL DAY AND INTO THE FIRST PART OF NEXT WEEK. IN
ADDITION...IT WILL ALSO BRING BETTER OPPORTUNITIES FOR SHORTWAVES
TO RIDE OVER THE RIDGE AND INTO THE AREA LATER MONDAY AND MORE
LIKELY TOWARDS TUESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 126 PM EDT TUE MAY 21 2013
WITH SHALLOW COOL AIR DOME PERSISTING N OF SFC WARM FNT IN WI...
EXPECT LIFR CONDITIONS TO PREVAIL THIS FCST PERIOD. THE WORST
CONDITIONS WILL OCCUR WHERE/WHEN THE BACKING LLVL FLOW UPSLOPES.
VLIFR WX IS LIKELY TO PERSIST AT CMX INTO THIS EVNG BEFORE THE FLOW
BACKS TO A MORE NE DIRECTION AND WEAKENS THE UPSLOPE WIND COMPONENT
AT THAT SITE.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 PM EDT TUE MAY 21 2013
GIVEN WIDESPREAD AREA OF RA THAT IMPACTED MUCH OF LAKE SUP INTO THIS
MORNING...SOME RECENT SHIP OBS THAT INDICATED LO VISIBILITY...AND
SHALLOW COOL AIRMASS OVER THE LAKE...OPTED TO EXTENDED DENSE FOG
ADVY THRU TONIGHT. ARRIVAL OF DRIER AIR FROM THE NW ON WED WILL
SLOWLY DIMINISH THE FOG. OTHERWISE...NE WINDS UP TO 25 TO 30 KTS...
WITH SOME GALE FORCE GUSTS AT THE HIER PLATFORMS...WILL CONTINUE
STRONGEST OVER WESTERN LAKE SUP WHERE TERRAIN FUNNELING WILL ENHANCE
THE WIND SPEEDS.
GUSTY NORTHERLY WINDS ARE EXPECTED BEHIND THE LOW PRESSURE SYSTEM
ON WEDNESDAY NIGHT INTO THURSDAY...BUT LINGERING WARM AIR ALOFT
SHOULD KEEP WINDS IN 20-25KT RANGE. THEN...A HIGH PRESSURE RIDGE
BUILDING SOUTHEAST OVER THE UPPER GREAT LAKES FOR THURSDAY NIGHT
THROUGH THE WEEKEND WILL BRING LIGHT WINDS TO LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
DENSE FOG ADVISORY UNTIL 6 AM EDT /5 AM CDT/ WEDNESDAY FOR
LSZ162-243>249-263>267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
315 PM EDT TUE MAY 21 2013
LATEST UPDATE...
AFTERNOON PACKAGE
.SYNOPSIS...
ISSUED AT 315 PM EDT TUE MAY 21 2013
AN AREA OF LOW PRESSURE WILL DEVELOP OVER SOUTHEAST MISSOURI THIS
EVENING AND MOVE THROUGH CENTRAL MICHIGAN ON WEDNESDAY. THE
DEVELOPING LOW CENTER WILL BRING SOAKING RAINS AND A FEW STRONG
THUNDERSTORMS TO THE AREA LATE TONIGHT AND WEDNESDAY. MUCH COOLER
AIR AND SHOWERS WILL WRAP IN FROM THE NORTHWEST AS THE LOW DEPARTS
ON THURSDAY. CANADIAN HIGH PRESSURE WILL BUILD OVER THE REGION
THURSDAY NIGHT AND PROVIDE COOL AND DRY WEATHER THROUGH THE HOLIDAY
WEEKEND. THERE WILL ALSO BE A GOOD CHANCE OF A SCATTERED FROST ON
BOTH FRIDAY AND SATURDAY MORNING.
&&
.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 315 PM EDT TUE MAY 21 2013
THREATS ARE THREE FOLD NEXT FEW DAYS WITH ISOLATED STRONG/SEVERE
STORMS THIS EVENING...HEAVY RAIN AND POSSIBLE LOCAL FLOOD POTENTIAL
ON WEDNESDAY... AND THEN MUCH COOLER AIR WITH A LATE SEASON FROST
THREAT BOTH FRI AND SAT MORNING...
LIKE RECENT HRRR GUIDANCE INDICATING ISOL TO SCATTERED TSTORM
COVERAGE SOUTH AND EAST OF KBEH...KY70...KMOP LINE THIS EVENING.
OVERALL COVERAGE AND POTENTIAL FOR ORGANIZATION WILL BE SUPPRESSED
BY MODEST SHORTWAVE RIDGING AND UPPER CONVERGENCE. INITIAL FOCUS IS
AN AXIS OF 1000 J/KG MUCAPE STRETCHING FROM KGRR TOWARDS THE THUMB.
THAT COMBINED WITH 35KTS BULK 0-6KM SHEAR WILL LIKELY GIVE RISE TO
SOME STRONG AND POSSIBLY SEVERE PULSE TYPE STORMS.
HEAVY RAIN THREAT ON WEDNESDAY WITH SFC CYCLOGENESIS AND MID LEVEL
FRONTOGENESIS AS NICE SHORTWAVE MOVES NORTHEASTWARD FROM MO/AR THIS
EVENING CROSSING THE REGION WED. BOTH ECMWF AND GFS AS WELL AS SOME
OF THE SHORTER TERM MESO GUIDANCE ALL INDICATE A 75 WIDE 1-2 INCH
BAND OF RAIN ORIENTED SSW TO NNE ON WEDNESDAY. THE MOISTURE AND
DYNAMICS ARE CERTAINLY IN POSITION TO SUPPORT THE RAINFALL...IT IS
JUST WHERE THE AXIS OF THE HEAVIER RAINFALL WILL BE. AT THIS POINT
FEEL THE BEST BET WOULD BE JUST ABOUT ON A KAZO...KGRR...KMOP LINE
WITH KMKG ABOUT AS FAR WEST AS IT MIGHT BE AND KLAN AS FAR EAST.
WRAP AROUND MOISTURE AND MUCH COOLER AIR MOVE IN BY THURSDAY AS
UPPER LOW OVER MN OPENS AND SWINGS EASTWARD THROUGH THE REGION. H85
TEMPS DROP TO NEAR ZERO BY THU EVENING WITH MUCH DRIER SFC DEWPOINT
DRIVING INTO THE REGION AS UPSTREAM CANADIAN SFC HIGH BUILD
OVERHEAD. FEEL PREETY CONFIDENT ABOUT FROST POTENTIAL FRI AND SAT
MORNING...ESPECIALLY UP NORTH AND IN SHELTERED LOW LYING AREAS
EVERYWHERE. NOT SURE WHICH MORNING WILL BE THE COLDER...FRI HAS THE
COLDER OVERALL AIRMASS BUT BOUNDARY LAYER WINDS WILL INHIBIT
RADIATIONAL COOLING.
&&
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 315 PM EDT TUE MAY 21 2013
THE LONG TERM PORTION OF THE FCST PERIOD LOOKS RATHER QUIET FOR
LOWER MICHIGAN. THE UPPER AIR PATTERN WILL TAKE ON SOME OF THE
CHARACTERISTICS OF AN OMEGA BLOCK. THIS OCCURS AS THE TROUGH/LOW
MOVING THROUGH MID WEEK HELPS TO ESTABLISH AN UPPER LOW ACROSS THE
NE U.S. AND THE CANADIAN MARITIMES. AN UPPER LOW WILL BECOME
ESTABLISHED ACROSS THE WRN U.S. COAST...WITH A RIDGE HOLDING ON IN
THE CENTRAL PORTION OF THE COUNTRY.
LOWER MICHIGAN SHOULD END UP UNDER THE DRY PORTION DOWNSTREAM OF THE
RIDGE AS IT SITS ALMOST STATIONARY. COOL NW FLOW ALOFT WILL KEEP
HIGHS IN THE 60S FROM FRI AND LIKELY THROUGH SUN WITH H850 TEMPS
ROUGHLY FROM 3-5C. WE STILL ARE EXPECTING SOME FROST POTENTIAL UP
NORTH ON FRI NIGHT BEFORE THE AIR MASS MODERATES SOME FOR THE
REMAINDER OF THE WEEKEND.
A WEAK SHORT WAVE WILL PUSH THROUGH THE REGION LATE SUN AND SUN
NIGHT. RIGHT NOW IT SEEMS THAT THIS SHOULD MOVE THROUGH DRY AS THE
LONG WAVE RIDGE SHOULD OVERCOME THIS WEAK SHORT WAVE. ALSO THE AIR
MASS SHOULD BE FAIRLY DRY WITH THE RIDGE SITTING OVER THE AREA FOR A
FEW DAYS AND NO GOOD MOISTURE ADVECTION EXPECTED THROUGH SUN.
SOME SPORADIC MODEL RUNS HAD BEEN SHOWING A WARM FRONT APPROACHING
LATE SUN AND REMAINING THROUGH TUE. THIS WOULD HAVE BROUGHT SOME
RAIN CHCS TO THE AREA. IT APPEARS NOW THAT THE NW FLOW ALOFT SHOULD
KEEP THIS FRONT SW OF THE AREA UNTIL AT LEAST TUE BEFORE SOME LOW
CHCS OF SHOWERS/STORMS WOULD DEVELOP. TEMPS WILL WARM INTO THE 70S
BY TUE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 137 PM EDT TUE MAY 21 2013
THE MAIN FOCUS OF THE 18Z FCSTS IS ONCE AGAIN CONVECTION TRENDS
OVER THE NEXT 24 HOURS.
THE AREA HAS BEEN SLOW TO HEAT UP SIGNIFICANTLY THIS MORNING DUE
TO THE RAIN EARLY THIS MORNING AND THE MID LEVEL CLOUD COVER THAT
HAS BEEN PLAGUING THE AREA. MORE BREAKS ARE OPENING UP...AND
INSTABILITY IS BUILDING. WE EXPECT JUST SPOTTY STORMS TO DEVELOP THIS
AFTERNOON ALONG AND INLAND OF THE LAKE BREEZE/LAKE SHADOW...MAINLY SE
OF A LINE FROM SOUTH HAVEN TO CADILLAC. SPOTTY MVFR CONDITIONS
SHOULD LIFT TO VFR EXCEPT DIRECTLY UNDER ANY STORMS THAT DEVELOP.
WE SHOULD SEE A BREAK IN CONVECTION THIS EVENING AND DURING THE
EARLY OVERNIGHT HOURS. WE WILL SEE THE CHCS OF RAIN INCREASE AFTER
08-10Z WED AS A WAVE OF LOW PRESSURE APPROACHES. THIS SHOULD BE
MAINLY SHOWERS/RAIN WITH ONLY A FEW EMBEDDED STORMS DOWN SOUTH.
THE STORM CHCS ARE LOW ENOUGH AT ANY ONE TERMINAL TO LEAVE OUT OF
THE FCST FOR NOW. WIDESPREAD MVFR CONDITIONS SHOULD ACCOMPANY THIS
PCPN WITH SOME LOCAL IFR NOT OUT OF THE QUESTION. THIS SHOULD HOLD
IN AT MOST LOCATIONS THROUGH 18Z BEFORE IT MOVES OUT AFTER 18Z WED.
&&
.MARINE...
ISSUED AT 315 PM EDT TUE MAY 21 2013
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED ON THURSDAY AS COLDER AIR
WRAPS IN BEHIND DEPARTING LOW PRESSURE SYSTEM. HIGH PRESSURE WILL
BRING QUIET AND COOL CONDITIONS FOR MOST IF NOT ALL OF THE HOLIDAY
WEEKEND.
&&
.FIRE WEATHER...
ISSUED AT 315 PM EDT TUE MAY 21 2013
THE AREA WILL SEE PERIODS OF RAIN THROUGH THURSDAY. OVER AN INCH OF
RAIN IS LIKELY KEEPING THE FIRE RISK LOW.
&&
.HYDROLOGY...
ISSUED AT 315 PM EDT TUE MAY 21 2013
PERIODS OF HEAVIER RAIN IS EXPECTED BY LATE TONIGHT AND SHOULD
LINGER UNTIL THURSDAY. SOME TYPICAL LOCALIZED FLOODING IS POSSIBLE
BY WEDNESDAY AFTERNOON IN LOW LYING URBAN AND RURAL AREAS AND ON
SMALL STREAMS AND RIVERS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...DKC
SHORT TERM...DKC
LONG TERM...NJJ
AVIATION...NJJ
FIRE WEATHER...DKC
HYDROLOGY...DKC
MARINE...DKC
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
117 PM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
A DEEP SOUTHWEST FLOW WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH THE TAF PERIOD. WHILE THIS WILL LEAVE THE LOCAL ENVIRONMENT
RELATIVELY MOIST AND UNSTABLE...PROSPECTS OF THUNDERSTORM
DEVELOPMENT REMAIN QUITE ILL-DEFINED. RECENT OBSERVATIONAL/
SATELLITE TRENDS AND MODEL GUIDANCE WOULD SUGGEST ANY POTENTIAL
DEVELOPMENT LATE THIS AFTERNOON WILL TEND TO REMAIN WIDELY
SCATTERED IN COVERAGE. A DEEPENING MIXED LAYER WILL LEAD TO SOME
SOUTHWESTERLY WIND GUSTS IN THE 20 KNOTS RANGE THROUGH PEAK HEATING.
FOR DTW...A LOW PROBABILITY DOES EXIST FOR THUNDERSTORMS TO IMPACT
THE TERMINAL LATE THIS AFTERNOON AND EVENING. HOWEVER THE POTENTIAL
NOW APPEARS TOO LIMITED GIVEN THE QUESTION OF COVERAGE TO INCLUDE
A SPECIFIC MENTION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM OCCURRANCE FROM MID AFTERNOON INTO
THE EVENING.
&&
.PREV DISCUSSION...ISSUED 1013 AM EDT TUE MAY 21 2013
UPDATE...
SE MICHIGAN REMAINS LODGED WITHIN A DEEP/MOIST AND PROGRESSIVELY
DESTABILIZING SOUTHWEST FLOW LATE THIS MORNING. SEVERAL HOUR WINDOW
OF NEARLY FULL INSOLATION CERTAINLY HELPING THIS PROCESS...ALTHOUGH
THE NORTHERN EXTENSION OF THE REMNANT CLOUD DEBRIS ATTACHED TO THE
LEFTOVER WEAK PV FILAMENT STREAMING INTO WEST-CENTRAL OHIO WILL
BEGIN TO FILTERING THE HEATING COMPONENT SLIGHTLY HEADING INTO
MIDDAY. HOWEVER GIVEN CURRENT TRENDS...HIGH TEMPERATURES OF LOWER
TO MIDDLE 80S CERTAINLY ARE ATTAINABLE. THIS PROJECTS TO ROUGHLY
1500 J/KG OF MLCAPE FOR THIS AFTERNOON.
DESPITE THIS EMERGING LOW LEVEL INSTABILITY GRADIENT...DELINEATING
BOTH THE LOCATION AND SCALE OF CONVECTIVE DEVELOPMENT...BOTH
UPSTREAM AND LOCALLY...REMAINS A CHALLENGE FOR THE AFTERNOON AND
EVENING PERIOD. 12Z DTX SOUNDING AND RECENT MODEL GUIDANCE SUGGEST
SOME DEGREE OF CAPPING REMAINS IN PLACE...ALBEIT NOT NEARLY AS
STRONG AS NOTED YESTERDAY. CONVECTIVE INITIATION MAY BECOME TIED TO
ADDITIONAL WEAK SHORTWAVE ENERGY AND ON THE LEAD EDGE OF AN
EXPANDING DIFFERENTIAL HEATING ZONE WORKING ACROSS MISSOURI AND INTO
SOUTHERN ILLINOIS. RECENT HI RES MODEL GUIDANCE PROVIDE FEW
CLUES...SUGGESTING A WINDOW FOR ISOLATED/SCATTERED DISCRETE CELL
DEVELOPMENT IN THAT FAVORED 19-22Z PERIOD. GIVEN A SOLID BACKGROUND
THERMODYNAMIC ENVIRONMENT TO MAINTAIN UPDRAFT STRENGTH...THE
PRESENCE OF A SUPPORTIVELY DEEP LAYER WIND FIELD WILL MAINTAIN A
RISK OF DAMAGING WINDS AND HAIL WITH ANY CELLS THAT CAN ORGANIZE
THROUGH THE PEAK HEATING CYCLE.
MINOR UPDATE ISSUED ALREADY TO READJUST POPS THROUGH THE EVENING AND
TWEAK TEMPERATURES BASED ON RECENT TRENDS.
PREV DISCUSSION...ISSUED 738 AM EDT TUE MAY 21 2013
UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....MR
UPDATE.......MR
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1235 PM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 1019 AM CDT TUE MAY 21 2013
FORECAST HAS BEEN UPDATED FOR WINDS THROUGH THE DAY. SURFACE LOW
CENTERED OVER EAST CENTRAL SOUTH DAKOTA THIS MORNING HAS ENHANCED
THE PRESSURE GRADIENT OVER NEBRASKA...WITH WINDS NOW BLOWING AT 20
TO 30 MPH WITH GUSTS UP TOWARDS 40 MPH IN PLACES. MODELS ARE
INDICATING WINDS WILL PEAK FROM NOW THROUGH AROUND 20Z...THEN AS
THE LOW SHIFTS EAST...THE STRONGER WINDS WILL SHIFT EASTWARD AS
WELL. AFTERNOON MIXING...WITH STRONG WINDS JUST ABOVE THE SURFACE
WILL KEEP THE WINDS UP THROUGH THE AFTERNOON...WITH A DECREASING
TREND THIS EVENING. THERE ARE A FEW SPOTS THAT HAVE BRIEFLY
REACHED WIND ADVISORY CRITERIA...BUT THINKING THIS WILL NOT BE
WIDESPREAD ENOUGH...OR WITH LONG ENOUGH DURATION AND WILL BE RIGHT
AT THE LOWER THRESHOLD FOR A WIND ADVISORY IF LOCATIONS DO HIT
ADVISORY CRITERIA WITH SUSTAINED AT 30 MPH AND GUSTS OVER 40 MPH.
OTHERWISE...TEMPERATURES ARE ON TREND...WITH HIGHS ONLY EXPECTED
IN THE UPPER 50S AND LOW 60S AS QUITE A BIT OF CLOUD COVER WILL BE
IN PLACE THROUGH THE DAY. ISOLATED TO SCATTERED LIGHT SHOWERS IN
THE FORECAST ARE ALSO ON TRACK AS THEY ROTATE AROUND THE LOW
PRESSURE SYSTEM. SO NO CHANGES IN THE PRECIPITATION FORECAST FOR
THE DAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1234 PM CDT TUE MAY 21 2013
WINDS WILL STAY BREEZY TO STRONG AT TIMES ACROSS MUCH OF WESTERN
AND NORTH CENTRAL NEBRASKA THROUGH EARLY THIS EVENING. WINDS WILL
STAY A BIT HIGHER OVER NORTH CENTRAL NEBRASKA OVERNIGHT AS THE
AREA OF LOW PRESSURE...OVER EASTERN SOUTH DAKOTA THIS AFTERNOON
MOVES EASTWARD THROUGH WEDNESDAY MORNING. THE LIGHT RAIN SHOWERS
ACROSS THE AREA WILL CONTINUE TO ROTATE AROUND THIS LOW PRESSURE
SYSTEM...WHICH WILL KEEP ISOLATED TO SCATTERED SHOWERS TO
LOCATIONS...MAINLY NORTH OF INTERSTATE 80 THROUGH EARLY
EVENING...AND POSSIBLY IN AREAS EAST OF A KVTN TO KBBW LINE
TONIGHT. CLOUDS WILL REMAIN ACROSS MUCH OF THE AREA
OVERNIGHT...WITH HIGH PRESSURE BUILDING INTO THE REGION ON
WEDNESDAY. MVFR CEILINGS LOOK LIKELY OVER WESTERN INTO SOUTHWEST
NEBRASKA THROUGH MID MORNING WEDNESDAY...WHILE IFR CEILINGS AND
MAYBE SOME 4SM VISIBILITIES ARE LOOKING LIKELY OVER NORTH CENTRAL
NEBRASKA THROUGH THE SAME TIME FRAME. AS THE SURFACE HIGH BUILDS
IN ON WEDNESDAY...CONDITIONS WILL IMPROVE FROM WEST TO EAST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BROOKS
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...BROOKS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
323 PM EDT TUE MAY 21 2013
.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON WILL DISSIPATE
THIS EVENING. SHOWER AND THUNDERSTORM ACTIVITY WILL DECREASE ON
WEDNESDAY WITH TEMPERATURES WARMING A LITTLE. SHOWERS AND
THUNDERSTORMS WILL INCREASE ON THURSDAY AHEAD OF A COLD FRONT THAT
WILL CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER WILL
DEVELOP FOR THE WEEKEND. TEMPERATURES WILL RETURN TO NORMAL EARLY
NEXT WEEK AS HIGH PRESSURE MOVES OFF THE EAST COAST.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 3 PM TUESDAY...CONVECTION NOW FOCUSED ALONG WHAT APPEARS TO
BE DIFFERENTIAL HEATING BOUNDARY. HEATING REALLY THE ONLY FORCING
IN THE ABSENCE OF ANY ASCENT ABOVE THE BOUNDARY LAYER BUT LCLS ARE
VERY LOW. LAPSE RATES SO WEAK THROUGH THE COLUMN THAT LIGHTNING
HAS BEEN MINIMAL DESPITE SOME OF THE TALLER CELLS REACHING THE EL
OF ABOUT 40KFT. DESPITE THIS IMPLIED VERY WEAK UPDRAFT SPEED THE
COLUMN IS NEARLY SATURATED AND RAINFALL WILL STILL BE HEAVY UNDER
MOST OF THE SHOWERS BUT THEIR SHORT DURATION IN ANY GIVEN LOCATION
WILL MINIMIZE FLOODING CONCERNS...WHICH ARE LOW BUT STILL NON-
ZERO. BEING BORNE OF NOTHING MORE THAN HEATING THE CONVECTION
SHOULD DWINDLE THROUGH THE EVENING AND A RAIN-FREE NIGHT IS
EXPECTED. HOW MUCH CLOUD COVER LINGERS IS A LITTLE UNCERTAIN AND
IS PROBABLY THE MAIN FORECAST CHALLENGE AT THIS TIME WITH POSSIBLE
MINOR RAMIFICATIONS FOR THE LOW TEMPERATURE FORECAST.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...DEEP SOUTH TO SOUTHWEST FLOW FOR MUCH OF THE
PERIOD WILL CONTINUE TO PUMP PLENTY OF GULF MOISTURE INTO THE
REGION. BERMUDA HIGH AND MID LEVEL RIDING OVER THE WESTERN ATLANTIC
BRIEFLY EXPAND WEST WED. INCREASE IN MID LEVEL SUBSIDENCE WILL
LIMIT COVERAGE OF AFTERNOON SHOWERS AND THUNDERSTORMS. DIURNAL
INSTABILITY ALONG WITH PRECIPITABLE WATER VALUES AROUND 1.7 INCHES
AND CONVERGENCE ALONG THE SEA BREEZE HOWEVER SUGGEST POP WILL NOT
BE ZERO. GIVEN THE LIMITING FACTORS SLIGHT CHANCE TO LOW CHANCE
SEEMS REASONABLE WITH INLAND SC FAVORED. WORTH NOTING THAT THE 12Z
NAM IS NOT AS AGGRESSIVE WITH THE BUILDING RIDGE AND IS SLOWER TO
EXIT THE SHORTWAVE REMNANTS. DISCOUNTING THIS SCENARIO FOR NOW AS
IT IS A SIGNIFICANT CHANGE FROM PREVIOUS SOLUTIONS BUT SHOULD IT
VERIFY POP WOULD NEED TO BE MUCH HIGHER.
MID LEVEL RIDGE QUICKLY WEAKENS THU WITH 5H TROUGH APPROACHING FROM
THE WEST. WHILE THE LOCAL ENVIRONMENT REMAINS RELATIVELY
UNCHANGED...DEEP SOUTHERLY FLOW PUSHES PWATS NEAR 1.8 INCHES...THE
LOSS OF SUBSIDENCE WILL RESULT IN A SIGNIFICANT INCREASE IN STORM
COVERAGE. IN ADDITION ANOTHER STRETCHED SHORTWAVE WILL MOVE INTO THE
AREA FROM THE BAHAMAS EARLY THU. PVA AHEAD OF IT REACHES THE AREA
LATE WED NIGHT OR THU MORNING AND SHOULD ENHANCE CONVECTION. AS HAS
BEEN THE CASE OVER THE PAST FEW DAYS THE ENVIRONMENT IS NOT
SUPPORTIVE OF SEVERE WEATHER. HOWEVER DEEP WARM LAYER AND RELATIVELY
SLOW STORM MOTION WITH POTENTIAL FOR TRAINING STORMS WILL KEEP THE
FLOOD THREAT ELEVATED...ESPECIALLY IN AREAS THAT HAVE ALREADY
RECEIVED SIGNIFICANT RAINFALL THE LAST FEW DAYS.
CONVECTION WILL BE WINDING DOWN THU EVENING AS DRY AIR JUST AHEAD OF
THE 5H TROUGH AXIS AND SURFACE COLD FRONT STARTS TO MOVE IN. COLD
FRONT IS SLOW TO CROSS THE AREA...NOT REACHING THE COAST UNTIL CLOSE
TO THE END OF THE PERIOD...BUT ALOFT WESTERLY FLOW STARTS DEVELOPING
BEFORE 00Z FRI. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO...WITH
NUMBERS TEMPERED BY CLOUDS IN SOME AREAS WHILE LOWS CONTINUE TO RUN
ABOVE CLIMO.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 3 PM TUESDAY...CHANGE IN AIR MASS EXPECTED ON FRIDAY AS
COLD FRONT MAKES ITS WAY OFF SHORE AND COOL CANADIAN HIGH PRESSURE
BUILDS IN. EXPECT COOLER AND DRIER AIR TO MAKE ITS WAY INTO THE
COASTAL CAROLINAS IN DEEP WEST TO NORTHWEST FLOW. PCP WATER VALUES
UP ABOVE 1.5 INCHES OVER THE DAYS LEADING UP TO FRIDAY WILL DROP
OUT TO LESS THAN AN INCH BY FRI AFTN AND BE DOWN TO LESS THAN A
HALF INCH BY SAT MORNING AS ATMOSPHERIC COLUMN DRIES OUT.
THEREFORE DO NOT EXPECT ANY PCP THROUGH THE WEEKEND IN A
RELATIVELY COOLER AND DRIER NORTHERLY FLOW.
AS FOR TEMPS...FRIDAY SHOULD MAKE IT INTO THE 80S IN MOST PLACES BUT
WILL FEEL COOLER AND DRIER BY THE END OF THE DAY. THE 850 TEMPS DROP
FROM CLOSE TO 15C PREVIOUS DAYS DOWN TO 8 TO 10C THROUGH THE
WEEKEND. SATURDAY AND SUNDAY TEMPS WILL REMAIN BETWEEN 75 TO 80 MOST
PLACES WITH MUCH LOWER DEWPOINTS REACHING DOWN INTO THE 40S INLAND
TO AROUND 50 ALONG THE COAST AS COMPARED TO 65 THE PREVIOUS DAYS.
WILL ALSO SEE MUCH GREATER DIURNAL SWINGS DUE TO THE DRY AIR MASS IN
PLACE. OVERNIGHT LOWS WILL REACH DOWN TO THE LOWER END OF THE 50S
BOTH FRI NIGHT AND SAT NIGHT IN COOL ADVECTION AND BETTER
RADIATIONAL COOLING SAT NIGHT AS HIGH PRESSURE SHIFTS OVERHEAD.
BY LATE SUNDAY INTO MONDAY THE HIGH PRESSURE WILL SHIFT OFF SHORE
GIVING WAY TO A WARMER MOISTER RETURN FLOW THROUGH EARLY NEXT WEEK.
THEREFORE WILL SEE A WARMING TREND. THE GFS SHOWS A WEAK COLD FRONT
DROPPING SOUTH INTO NORTH CAROLINA LATE MONDAY INTO TUES. THEREFORE
WILL SHOW CLOUDS AND CHC OF PCP BACK IN THE FORECAST HOLDING TO THE
NORTH ON MONDAY AND OVER LOCAL AREA BY TUES.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AS OF 18Z...MAINLY VFR/MVFR CONDITIONS ARE BEING REPORTED ACROSS THE
CWA THIS AFTN WITH SOUTH WINDS 8-12 KTS. CONVECTION HAS ALREADY
FIRED ALONG THE SEA BREEZE BOUNDARY THIS MORNING...MAINLY NEAR
KMYR/KCRE. MORE SHOWERS/T-STORMS ARE POSSIBLE TODAY WITH CONTINUED
DIURNAL HEATING. HAVE INCLUDED VCSH/VCTS AT ALL TERMS THROUGH
00Z...ALTHOUGH THE LATEST HRRR RUNS SUGGEST PCPN THIS AFTN MAY BE
MORE CONCENTRATED INLAND. VERY BRIEF PERIODS OF IFR ARE POSSIBLE IN
HEAVIER DOWNPOURS. THE ABUNDANT LOW-LEVEL MOISTURE IN PLACE COULD
ALLOW MVFR CIGS/VSBYS TO DEVELOP OVERNIGHT. EXPECT MOSTLY CLOUDY
CONDITIONS AGAIN ON WEDNESDAY WITH SOUTH WINDS AROUND 8-12 KTS.
EXTENDED OUTLOOK...SLIGHT CHC OF SHOWERS WEDNESDAY. SHOWERS/T-STORMS
POSSIBLE THURSDAY THROUGH EARLY FRIDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM TUESDAY...NOT MUCH CHANGING THROUGH THE PERIOD FROM
THE CONDITIONS THAT HAVE BEEN IN PLACE FOR QUITE SOME TIME NOW.
SOUTH TO SOUTHWESTERLY WINDS WILL RUN IN THE 10 TO 15 KT RANGE ON
AVERAGE. SEAS WILL BE IN THE 3 TO 4 FT RANGE AND BE A LITTLE ON
THE CHOPPY SIDE WITH A PERIOD OF 4-6 SECONDS. THERE IS STILL SOME
SWELL ENERGY OUT OF THE ESE AT ABOUT 9 SEC BUT IT IS SHOWING UP AS
A MUCH LESSER WAVE COMPONENT IN SPECTRAL PLOTS.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...BERMUDA HIGH REMAINS IN CONTROL WED BEFORE
RETREATING EAST THU AHEAD OF A COLD FRONT EXPECTED TO CROSS THE
WATERS LATE THU NIGHT. WED BERMUDA HIGH MAINTAINS SOUTHERLY FLOW
WITH SPEEDS OF 10 TO 15 KT RANGE AND SEAS 2 TO 4 FT. WIND SPEEDS
INCREASE SLIGHTLY THEN VEER THU INTO THU NIGHT AS THE COLD FRONT
APPROACHES FROM THE WEST. WINDS WILL GENERALLY BE 10 TO 15 KT WITH
PERIODS OF SUSTAINED 15 KT LIKELY...ESPECIALLY IN THE AFTERNOON.
WINDS EVENTUALLY VEER TO WEST LATE THU NIGHT AS FRONT PASSES. SEAS
BRIEFLY RISE TO 3 TO 5 FT THU THEN DROP BACK TO 2 TO 4 FT AS PERIOD
ENDS.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 PM TUESDAY...COLD FRONT MOVING FARTHER ON FRIDAY AS
COOLER AND DRIER CANADIAN HIGH PRESSURE BUILDS IN BEHIND IT
THROUGH THE WEEKEND. WINDS WILL VEER AROUND FROM WEST AROUND 10
KTS FRIDAY MORNING...TO NORTH TO NORTHEAST AT 15 TO 20 KTS FRIDAY
NIGHT INTO SATURDAY IN COOL SURGE AND TIGHTENED GRADIENT. WINDS
WILL LIGHTEN AND CONTINUE TO VEER AS HIGH PRESSURE SHIFTS OVERHEAD
ON SUNDAY.
SEAS WILL BE ENTIRELY WIND-WAVE DOMINATED BETWEEN 3 AND 5 FT THROUGH
FRI INTO SATURDAY. BY LATE SATURDAY INTO SUNDAY...THE SEAS WILL
SUBSIDE AND WINDS LIGHTEN AS HIGH SHIFTS CLOSER OVERHEAD. EXPECT
SEAS DOWN TO 3 FT OR LESS BY SAT NIGHT INTO SUNDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MBB
SHORT TERM...III
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
130 PM EDT TUE MAY 21 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER
WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM TUESDAY...ITS PRETTY HARD TO ADD MUCH SPECIFICITY TO
THE FORECAST ON A DAY LIKE TODAY. CURRENTLY CONVECTION IS WINDING
DOWN OVER THE WRN ZONES WHILE THE SEABREEZE IS LIGHTING UP NICELY
WITH SHOWERS THAT WHILE HEAVY WILL BE SO SHORT-LIVED THE ACTUAL
RAINFALL AMOUNTS WILL BE QUITE LIGHT OVER A GIVEN LOCATION. HOW MUCH
ACTIVITY REFIRES OVER WESTERN ZONES WILL LARGELY BE A FUNCTION OF
HEATING DUE THE ABSENCE OF ANY MEANINGFUL LARGE SCALE LIFT. THERE
WILL ALSO BE A TENDENCY FOR THE IMMEDIATE COAST TO SEE LESS ACTIVITY
EAST OF THE SEA BREEZE...WHICH WILL NOT MOVE MUCH INLAND AT ALL
TODAY. IN FACT IT MAY NOT MOVE MUCH FROM ITS CURRENT LOCATION WHICH
COULD NECESSITATE RAISING POPS ALONG THE GRAND STRAND. STORM MOTION
ALSO SHOWING CONSIDERABLE VARIABILITY TODAY DUE TO THE LEFTOVER
UPPER SHEAR AXIS OVER THE REGION.
AS OF 700 AM TUESDAY...A LARGE CLUSTER OF THUNDERSTORMS PRODUCING
HEAVY RAIN HAS DEVELOPED ACROSS THE SANDHILLS AND SOUTHERN PIEDMONT
OF NC. THIS CONVECTION IS DRIFTING SOUTHEASTWARD...PIVOTING AROUND
THE INLAND SIDE OF THE UPPER SHEAR AXIS THAT IS LINED UP ALONG THE
INTERSTATE 95 CORRIDOR. THE LATEST SEVERAL HRRR MODEL RUNS TAKE THIS
CONVECTION SOUTHEASTWARD INTO THE BENNETTSVILLE AND DARLINGTON AREA
OVER THE NEXT COUPLE OF HOURS...BUT DIVERGE FROM RUN TO RUN AS TO
WHAT HAPPENS LATER THIS MORNING. PRIOR RUNS SHOWED THE CONVECTION
CONTINUING TO RUN SOUTH/SOUTHEASTWARD THROUGH NOON...WHILE THE
LATEST RUN (08Z) DISSIPATES THE CURRENT CLUSTER WHILE DEVELOPING NEW
CONVECTION JUST INLAND FROM THE COAST BY LATE MORNING AHEAD OF THE
DEVELOPING SEABREEZE BOUNDARY.
THE TAKE-HOME MESSAGE FROM ALL THIS IS THAT WE HAVE AN AIRMASS THAT
REALLY WANTS TO PRODUCE CONVECTION GIVEN ANY POSSIBLE REASON.
CONVECTIVE OUTFLOW BOUNDARIES FROM THE CURRENT ACTIVITY PLUS THE
DEVELOPMENT OF A SEABREEZE THIS AFTERNOON SHOULD ENSURE THERE ARE
PLENTY OF REASONS FOR NEW CONVECTIVE DEVELOPMENT...THEREFORE I HAVE
RAISED POPS INTO THE LIKELY CATEGORY FOR MOST AREAS MORE THAN 20
MILES INLAND FROM THE COAST TODAY. WEST OF INTERSTATE 95 I HAVE
RAISED POPS INTO THE 70-90 PERCENT RANGE...ANTICIPATING THE CURRENT
SANDHILLS CONVECTION WILL SOAK THIS AREA IN THE NEXT FEW HOURS.
RAINFALL OVER THE PAST THREE DAYS HAS AVERAGED 2 TO 5 INCHES WEST OF
INTERSTATE 95 EXCEPT FOR THE WESTERN THIRD OF DARLINGTON COUNTY
WHERE BARELY ONE INCH HAS FALLEN. GIVEN SOME OF THE RADAR-ESTIMATED
TOTALS FROM ROCKINGHAM TO WEST OF CHERAW THIS MORNING IT IS POSSIBLE
FLOOD ADVISORIES OR WARNINGS MAY BE NEEDED IN MY PEE DEE COUNTIES IN
THE NEXT SEVERAL HOURS.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN THIS RECENT WET PERIOD
SEVERAL DAYS AGO HAS DEGENERATED INTO A 500-TO-700 MB SHEAR AXIS.
WIND SPEEDS SURROUNDING THE UPPER FEATURE ARE TOO WEAK AT THIS POINT
TO SUPPORT DYNAMIC LIFT...BUT RICH LOW AND MID LEVEL MOISTURE
REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS WITH PRECIPITABLE
WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY CONVECTIVE
CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY STEEPER THAN THE
MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S SEABREEZE BOUNDARY
SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION (NEARLY 10000
FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE PROCESSES WILL
DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS THIS AFTERNOON
SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /18Z TUESDAY THROUGH SATURDAY/...
AS OF 18Z...MAINLY VFR/MVFR CONDITIONS ARE BEING REPORTED ACROSS THE
CWA THIS AFTN WITH SOUTH WINDS 8-12 KTS. CONVECTION HAS ALREADY
FIRED ALONG THE SEA BREEZE BOUNDARY THIS MORNING...MAINLY NEAR
KMYR/KCRE. MORE SHOWERS/T-STORMS ARE POSSIBLE TODAY WITH CONTINUED
DIURNAL HEATING. HAVE INCLUDED VCSH/VCTS AT ALL TERMS THROUGH
00Z...ALTHOUGH THE LATEST HRRR RUNS SUGGEST PCPN THIS AFTN MAY BE
MORE CONCENTRATED INLAND. VERY BRIEF PERIODS OF IFR ARE POSSIBLE IN
HEAVIER DOWNPOURS. THE ABUNDANT LOW-LEVEL MOISTURE IN PLACE COULD
ALLOW MVFR CIGS/VSBYS TO DEVELOP OVERNIGHT. EXPECT MOSTLY CLOUDY
CONDITIONS AGAIN ON WEDNESDAY WITH SOUTH WINDS AROUND 8-12 KTS.
EXTENDED OUTLOOK...SLIGHT CHC OF SHOWERS WEDNESDAY. SHOWERS/T-STORMS
POSSIBLE THURSDAY THROUGH EARLY FRIDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE OVERALL SYNOPTIC
WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH PRESSURE HAS DROPPED
SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE NORTHERN PLAINS IS
STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS WILL ENSURE A SOUTH
WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH TONIGHT. SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE MOST NUMEROUS THIS
MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE CLEARING OUT MOST OF
THIS ACTIVITY FROM THE COASTAL WATERS THIS AFTERNOON. SEAS CURRENTLY
RANGE FROM 3-4 FT ON BUOYS IN THE CAPE FEAR VICINITY...IN A
COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6 SECOND SOUTHERLY
WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...MBB/TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS BISMARCK ND
326 PM CDT TUE MAY 21 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 327 PM CDT TUE MAY 21 2013
THE HIGHLIGHT OF THE SHORT TERM IS THE END OF THE LONG DURATION
RAINFALL EVENT ACROSS THE AREA.
FOR TONIGHT...THE RAP THROUGHOUT THE DAY HAS HAD A GOOD HANDLE ON
THE STRATUS DECK ACROSS THE AREA..AND FOLLOWED ITS LATEST 19 UTC
RUN FOR CLOUD COVER THROUGH THE NIGHT WHICH ADVECTS DRIER AIR
SOUTHWEST AND SCOURS OUT THE STRATUS. DID ADD A MENTION OF FOG TO
THE NORTHWEST AND NORTH CENTRAL WHERE SKIES FIRST CLEAR TONIGHT
AND WINDS BECOME LIGHT...ALLOWING FOR GOOD RADIATIONAL COOLING
INTO THE UPPER 30S AND SATURATION IN LIGHT OF THE RECENT RAINFALL.
A QUIET WEDNESDAY IS FORECAST WITH A SURFACE RIDGE AXIS ACROSS THE
AREA. GIVEN GOOD MODEL AGREEMENT...USED A BLEND OF THE 12 UTC
GEM/GFS/NAM/ECMWF AND 15 UTC SREF FOR ALL FIELDS...WITH GENERALLY
SUNNY SKIES AND HIGHS IN THE 60S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 327 PM CDT TUE MAY 21 2013
BY WEDNESDAY NIGHT AN UPPER LEVEL SHORTWAVE RIDGE BETWEEN THE
EXITING LOW PRESSURE SYSTEM TO THE EAST...AND THE ESTABLISHED UPPER
LEVEL LOW OVER THE WEST COAST/ROCKIES...WILL BE SITUATED OVER THE
PLAINS OF NORTH AMERICA. AT THE SURFACE...COOL HIGH PRESSURE RIDGE
MOVING SOUTH FROM CANADA NOSES INTO THE DAKOTAS.
BY THURSDAY THE SURFACE PRESSURE GRADIENT INCREASES AS THE
INTENSIFYING SURFACE LOW OVER THE ROCKIES/LEE OF THE ROCKIES SETS UP
A STRONGER SOUTHERLY/SOUTHEASTERLY WIND FLOW ACROSS THE WESTERN
PLAINS. SOUTHEAST WINDS 20 TO 30 MPH CAN BE EXPECTED OVER THE
WESTERN THIRD OF NORTH DAKOTA.
FRIDAY THROUGH THE MEMORIAL DAY WEEKEND...THE LARGE UPPER LEVEL LOW
OVER THE ROCKIES SETS UP A SOUTHWEST FLOW ALOFT OVER NORTH
DAKOTA...AND A SERIES OF UPPER LEVEL IMPULSES WILL TRAVERSE
NORTHEASTWARD ACROSS THE DAKOTAS. THUS A CHANCE OF THUNDERSTORMS
THROUGHOUT THIS PERIOD.
FAIRLY SEASONABLE TEMPERATURES IN THE LONG TERM...WITH HIGHS IN THE
60S AND 70S AND LOWS IN THE 40S AND 50S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 327 PM CDT TUE MAY 21 2013
MVFR STRATUS WITH OCCASIONAL LIGHT RAIN WILL CONTINUE TO IMPACT
KMOT...KBIS...KJMS AND KDIK THIS AFTERNOON AND EVENING...WITH A
CLEARING TREND FROM NORTH TO SOUTH TONIGHT. HOWEVER...WITH
SUNSET...THE STRATUS DECK MAY LOWER TO IFR BEFORE CLEARING. KISN
SHOULD REMAIN OUTSIDE OF THIS DECK FOR THE 18 UTC TAF CYCLE WITH
VFR CONDITIONS EXPECTED. THERE IS A CHANCE OF FOG TONIGHT AT KMOT
AS SKIES CLEAR WITH RECENT RAINFALL...HOWEVER...IMPACTS ARE STILL
UNCERTAIN AT THIS TIME AND WILL CODE AS VCFG FOR NOW.
&&
.HYDROLOGY...
ISSUED AT 327 PM CDT TUE MAY 21 2013
FLOOD WARNINGS CONTINUE FOR THE PIPESTEM CREEK NEAR PINGREE AND
THE FORECAST POINTS OF TOWNER...BANTRY AND WESTHOPE ON THE SOURIS.
CONTINUING TO MONITOR THE WINTERING RIVER NEAR KARLSRUHE AND THE
WILLOW CREEK NEAR WILLOW CITY WHICH MAY APPROACH FLOOD STAGE IN
THE NEXT 24-48 HOURS. HAVE HELD OFF ON A FLOOD WARNING FOR
NOW...AND WILL WATCH HOW THESE WATERWAYS RESPOND TO RUNOFF.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AYD
LONG TERM...JV
AVIATION...AYD
HYDROLOGY...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
115 PM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 115 PM CDT TUE MAY 21 2013
THE MAIN CHANGE WITH THIS FORECAST UPDATE WAS TO DECREASE SKY
COVER ACROSS THE FAR NORTHWEST AND NORTH CENTRAL...FOLLOWING THE
17 UTC RAP FOR CLOUD COVER THROUGH TONIGHT...WHICH HAS HANDLED THE
CLOUD SHIELD WELL SO FAR TODAY. ALSO...REMOVED THE MENTION OF
PRECIPITATION GENERALLY FOR US HIGHWAY 2 AND NORTH...AND REDUCED
POPS TO CHANCE FOR MOST OTHER LOCATIONS OUTSIDE OF THE JAMES RIVER
VALLEY BASED ON RADAR TRENDS.
UPDATE ISSUED AT 953 AM CDT TUE MAY 21 2013
NO SIGNIFICANT CHANGES REQUIRED WITH THIS FORECAST UPDATE AS THE
TREND THROUGH THE REMAINDER OF THE DAY WILL BE A DECREASE IN
PRECIPITATION CHANCES FROM NORTH TO SOUTH AS THE SURFACE LOW
ACROSS EASTERN SOUTH DAKOTA PROPAGATES INTO SOUTHERN MINNESOTA.
ALL MODELS ARE IN GOOD AGREEMENT WITH A BLEND OF THE 00 UTC
GEM/ECMWF...09 UTC SREF...06 UTC GFS AND 12 UTC NAM UTILIZED FOR
TEMPERATURES AND POPS.
UPDATE ISSUED AT 640 AM CDT TUE MAY 21 2013
GRADIENT FLOW HAS DECREASED ACROSS CENTRAL NORTH DAKOTA AS A SURFACE
LOW OVER EASTERN SOUTH DAKOTA WEAKENS AND SHIFTS FARTHER TO THE
SOUTHEAST. AS A RESULT...CANCELLED THE WIND ADVISORY FOR THIS
UPDATE.
OTHERWISE...ONLY MODIFIED HOURLY SENSIBLE WEATHER GRIDS BASED ON
CURRENT OBS/TRENDS. NO MAJOR UPDATES WERE REQUIRED TO THE ONGOING
FORECAST. THE UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 414 AM CDT TUE MAY 21 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE ONGOING
RAIN AND WIND ASSOCIATED WITH THE STORM SYSTEM OVER THE REGION.
CURRENTLY...LARGE STACKED LOW PRESSURE SYSTEM OVER THE NORTHERN
PLAINS...CENTERED OVER WESTERN SOUTH DAKOTA. SEVERAL EMBEDDED
VORTICITY MAXIMUMS/CYCLONIC CIRCULATIONS ROTATING AROUND/WITHIN
THE LARGE LOW. RAIN IS MORE SCATTERED IN NATURE THIS MORNING
COMPARED TO THE PAST FEW DAYS WITH MOST OBS REPORTING LIGHT
RAIN RATHER THAN MODERATE OR HEAVY. PRESSURE GRADIENT SLOWLY
DIMINISHING OVER MY EAST BUT AM STILL SEEING GUSTY WINDS AT ROLLA
AND RUGBY TO OVER 40 MPH. THUS WILL MAINTAIN THE WIND ADVISORY AS
IS EAST OF HIGHWAY 83 AND NORTH IF I94 WITH THIS FORECAST PACKAGE.
100KT JET STREAK SOUTHEAST OF THE LOW FROM EASTERN KANSAS
NORTHEAST INTO THE WESTERN GREAT LAKES REGION...ALONG WITH A
SOUTHERN STREAM S/WV TROUGH MOVING EAST ACROSS NORTHERN
TEXAS TODAY...WILL ALL HELP TO NUDGE THE UPPER LOW SLOWLY
SOUTHEAST BEGINNING THIS AFTERNOON...ALLOWING A RIDGE OF HIGH
PRESSURE OVER SOUTH CENTRAL CANADA TO BUILD SOUTHWARD INTO THE
NORTHERN PLAINS TONIGHT. SEVERAL MORE EMBEDDED WAVES ROTATING
AROUND THE LOW WILL STILL BRING LIGHT RAINFALL TO MOST LOCATIONS
THIS MORNING...BUT WILL SEE CHANCES DECREASE NORTH LATER
TODAY...WITH THIS TREND (DECREASING PRECIPITATION CHANCES FROM
NORTH TO SOUTH) CONTINUING TONIGHT. WITH LESS THAN A QUARTER OF AN
INCH OF ADDITIONAL RAINFALL NOW EXPECTED FROM THIS STORM
SYSTEM...WE OPTED TO CANCEL THE FLOOD WATCH WITH FURTHER
HYDROLOGIC IMPACTS EXPECTED TO BE MINIMAL.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 414 AM CDT TUE MAY 21 2013
LIGHT RAIN WILL CONTINUE TO TAPER OFF FROM NORTHWEST TO SOUTHEAST
WEDNESDAY AS HIGH PRESSURE BUILDS INTO WESTERN NORTH DAKOTA. DRY
CONDITIONS ARE EXPECTED AREA WIDE WEDNESDAY NIGHT AND WILL CONTINUE
THROUGH THURSDAY NIGHT AS A MID-LEVEL RIDGE AXIS CRESTS ACROSS THE
REGION. NEAR NORMAL TEMPERATURES ARE EXPECTED.
THE MEDIUM RANGE MODELS CONTINUE TO PROG AN UNSETTLED WEATHER
PATTERN TO DEVELOP OVER WESTERN AND CENTRAL NORTH DAKOTA FRIDAY
THROUGH THE WEEKEND...AND INTO MONDAY. SOUTHWESTERLY FLOW ALOFT WILL
DEVELOP AS AN UPPER LEVEL LOW SPINS OVER THE PACIFIC NORTHWEST.
PERIODIC ENERGY TRAVERSING THE MEAN FLOW ALOFT WILL GENERATE CHANCES
FOR THUNDERSTORMS. GIVEN THE TIMING UNCERTAINTY...CONTINUED TO BROAD
BRUSH A CHANCE FOR THUNDERSTORMS EACH DAY IN THE LATTER PART OF THE
EXTENDED. IT IS STILL TOO EARLY TO TRY AND TARGET WHICH DAY WILL
HAVE THE HIGHEST POTENTIAL FOR SEVERE WEATHER...IF ANY SEVERE
WEATHER DEVELOPS AT ALL. AS A RESULT...SIDED WITH THE SPC AND THINK
THE POTENTIAL FOR SEVERE WEATHER IS TOO LOW AT THIS TIME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 115 PM CDT TUE MAY 21 2013
MVFR STRATUS WITH SCATTERED LIGHT RAIN WILL CONTINUE TO IMPACT
KMOT...KBIS...KJMS AND KDIK THIS AFTERNOON AND EVENING...WITH A
CLEARING TREND FROM NORTH TO SOUTH TONIGHT. KISN SHOULD REMAIN
OUTSIDE OF THIS DECK FOR THE 18 UTC TAF CYCLE WITH VFR CONDITIONS
EXPECTED. THERE IS A CHANCE OF FOG TONIGHT AT KMOT AS SKIES CLEAR
WITH RECENT RAINFALL...HOWEVER...IMPACTS ARE STILL UNCERTAIN AT
THIS TIME AND WILL CODE AS VCFG FOR NOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...NH
LONG TERM...TM
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
137 PM EDT TUE MAY 21 2013
.SYNOPSIS...
THE AIR MASS WILL BECOME INCREASINGLY MOIST AND UNSTABLE THROUGH MID
WEEK AS AN AREA OF LOW PRESSURE OVER THE UPPER MIDWEST SLOWLY
APPROACHES THE REGION. THIS LOW PRESSURE SYSTEM WILL TRACK THROUGH
THE EASTERN GREAT LAKES LATE WEDNESDAY AND PUSH A COLD FRONT SOUTH
ACROSS THE AREA ON THURSDAY. HIGH PRESSURE WILL RETURN FOR THE END
OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AXIS OF WEAK LIFT MOVING EAST ACROSS THE CENTRAL PART OF THE CWA
ATTM. NEAR TERM MODELS GENERATE CONVECTION FROM THIS FEATURE OVER
THE SNOWBELT AREA BY 17Z WITH THE HRRR BY FAR THE MOST GENEROUS.
SINCE THE HRRR USUALLY TENDS TO BE OVERDONE WITH THIS TYPE OF
CONVECTION WILL ONLY RAMP UP A SLIGHT OR SMALL CHANCE POP FOR THIS.
OTHERWISE WILL GRADUALLY RAMP UP CHANCE POPS FOR SCT CONVECTION TO
DEVELOP DURING THE AFTERNOON BUT NOT SEEING THE COVERAGE AS
WIDESPREAD AS PREVIOUS THINKING. WILL INCREASE TEMPS OVER THE WEST
AND CENTRAL A LITTLE AS MID CLOUDS WILL BE ABSENT OVER THESE AREAS
FOR THE PEAK HEATING HOURS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
SOME LEFT OVER SHOWERS AND THUNDERSTORMS IN THE EVENING AND THEN
THE AREA SHOULD BE IN A LULL FOR MUCH OF TONIGHT AND THEN WAITING
FOR THE NEXT SYSTEM TO AFFECT THE REGION FOR WEDNESDAY INTO
WEDNESDAY NIGHT. THIS WILL BE THE DAY WITH THE BEST CHANCE OF
SEVERE WEATHER. THE COLD FRONT MOVES THROUGH ON THURSDAY. FRIDAY
SHOULD BE DRY AND COOL WITH HIGH PRESSURE BUILDING IN.
THE TEMPERATURE FORECAST IS TOUGH...ESPECIALLY THE HIGHS. IF THE
SHOWERS AND THUNDERSTORMS DEVELOP EARLY OR IF WE HAVE A LOT OF
DEBRIS CLOUDS THAT WILL AFFECT THE HIGHS. USED A BLEND OF GUIDANCE.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
MODELS IN DISAGREEMENT IN THE EXTENDED. GFS CONTINUES WITH CANADIAN
HIGH PRESSURE OVER THE ENTIRE AREA THROUGH THE WEEKEND. THE ECMWF
ON THE OTHER HAND HAS ANOTHER FRONT PUSH THROUGH THE AREA ON
SATURDAY...AND IS THUS WETTER AND COOLER. SINCE THE GFS HAS BEEN
CONSISTENT WITH THIS SOLUTION IGNORED THE ECMWF AND WENT WITH THE
GFS FORECAST. THIS WILL RESULT IN DRY NORTHERLY FLOW FOR THE AREA
FOR THE ENTIRE WEEKEND AND SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
MORE UNCERTAINTY TODAY AS FAR AS PRECIP CHANCES GO. MUCH DRIER AIR
HAS WORKED INTO THE WESTERN HALF OF THE AREA WITH DEWPOINTS DOWN
INTO THE 50S. HAVING A TOUGH TIME EVEN GETTING CU THAT AREA AND
PRECIP CHANCES THROUGH THE EVENING HOURS APPEAR MINIMAL. MODELS
SHOWING AN UPPER TROUGH MOVING INTO LOWER MI LATER TODAY WHICH
COULD KICK OFF SOME TSRA ACTIVITY. THIS ACTIVITY COULD COME CLOSE
TO KTOL. FURTHER EAST THE AIRMASS REMAINS MORE UNSTABLE. GUIDANCE
SUGGESTS SOME POP UP STORMS ARE POSSIBLE LATER THIS AFTERNOON.
WILL USE A COMBINATION OF TEMPOS AND VCTS FOR A FEW HOURS THIS
EVENING. THE OVERNIGHT HOURS SHOULD BE DRY WITH JUST PATCHY MVFR
FOG TOWARD DAYBREAK. WEDNESDAY SHOULD BE A MORE ACTIVE DAY AND
WILL BRING MORE PRECIP INTO THE WEST TOWARD MIDDAY. GUSTY S TO SW
FLOW WILL DIMINISH THIS EVENING.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS WEDNESDAY AND
THURSDAY.
&&
.MARINE...
SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON THE LAKE THROUGH MID WEEK.
MODELS HAVE BEEN CONSISTENT WITH THE NEXT SYSTEM MOVING ACROSS THE
LAKE ON THURSDAY. SMALL CRAFT ADVISORY WILL BE NEEDED AS NORTH TO
NORTHWEST WINDS INCREASE TO 15 TO 25 KNOTS IN COLDER AIR. THE 850MB
TEMPS DIP TO 2C BY THE WEEKEND. STRONG TO SEVERE STORMS APPEAR
POSSIBLE BOTH TODAY AND WEDNESDAY. BOATERS WILL NEED TO REMAIN
ALERT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...KUBINA
MARINE...DJB
AREA FORECAST DISCUSSION
NWS TULSA OK
312 PM CDT TUE MAY 21 2013
.DISCUSSION...
LINEAR MCS THAT HAS FORMED AHEAD OF COMPACT UPPER SYSTEM SURGING
ACROSS OK/TX IS CURRENTLY MOVING ACROSS PORTIONS OF SERN OK. THE
LINE HAS BEEN STRONG/MARGINALLY SEVERE SO FAR...AND STILL COULD SEE
SOME 60+ MPH WIND GUSTS OVER THE NEXT FEW HOURS. HRRR HAS SHOWN A
VERY GOOD HANDLE ON THE COMPLEX...WITH THE LEADING EDGE EXITING OUR
FORECAST AREA AROUND 22Z-23Z. CURRENT FLASH FLOOD WATCH IS SET TO
EXPIRE AT 00Z...ALTHOUGH MAY EXTEND IT A FEW MORE HOURS. WILL TAKE A
LAST LOOK AT RADAR BEFORE FINAL DECISION. OTHERWISE...PARTIALLY
CLEARING SKIES ALONG WITH DRIER LOW-LEVEL AIR WILL ALLOW TEMPS TO
FALL INTO THE 50S FOR MUCH OF THE AREA.
WEAK SURFACE BOUNDARY MAY BE PRESENT ACROSS THE AREA ON
WEDNESDAY...ALTHOUGH ATMOSPHERE SHOULD BE TOO DRY AND WORKED OVER TO
SUPPORT PRECIPITATION.
UPPER PATTERN WILL BECOME INCREASINGLY AMPLIFIED BY MID-TO-LATE
WEEK...WITH RIDGING THROUGH THE PLAINS SANDWICHED BY DEEP UPPER
SYSTEMS ACROSS THE PAC NW AND THE EAST COAST. MODELS SUGGEST THAT
SEVERAL WEAK WAVES WILL MOVE INTO THE MEAN RIDGE POSITION...WITH AT
LEAST SOME LOW POPS WARRANTED ACROSS WRN SECTIONS IN THE VERY
WARM/MOIST AIRMASS.
UPPER RIDGE SHOULD FLATTEN SOME ACROSS THE SRN/CENTRL PLAINS GOING
INTO THE WEEKEND. WITH THE FORECAST AREA ALONG THE SRN EDGE OF THE
STRONGER UPPER FLOW...SHOULD SEE PERIODIC SHOWER/THUNDERSTORM
EPISODES...ESPECIALLY ACROSS NE OK/NW AR. TOUGH TO PINPOINT WHICH
DAY WILL HAVE THE BEST CHANCES...SO HAVE MAINTAINED GENERAL CHANCE
POPS FOR ABOUT THE NRN HALF OF THE AREA FOR THE WEEKEND AND INTO
EARLY NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 55 81 58 78 / 40 0 10 20
FSM 58 83 62 81 / 80 10 10 10
MLC 55 83 61 84 / 40 0 10 20
BVO 52 81 54 77 / 20 0 10 20
FYV 54 79 55 76 / 80 10 10 10
BYV 56 79 55 77 / 80 10 10 10
MKO 55 82 60 79 / 60 10 10 20
MIO 54 78 56 78 / 50 10 10 10
F10 55 82 61 79 / 30 0 10 20
HHW 60 85 64 85 / 50 0 10 20
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...FLASH FLOOD WATCH UNTIL 7 PM TUESDAY FOR OKZ049-OKZ053-OKZ068-
OKZ069-OKZ070-OKZ071-OKZ072-OKZ073-OKZ074-OKZ075-OKZ076.
AR...FLASH FLOOD WATCH UNTIL 7 PM TUESDAY FOR ARZ001-ARZ002-ARZ010-
ARZ011-ARZ019-ARZ020-ARZ029.
&&
$$
SHORT TERM...06
LONG TERM....18
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
701 PM EDT TUE MAY 21 2013
.SYNOPSIS...
AN UPPER LEVEL AREA OF LOW PRESSURE WILL DRIFT EAST AND OFFSHORE
OVERNIGHT. A LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE
CENTRAL PLAINS INTO THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL
PUSH A COLD FRONT THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH
PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 310 PM EDT TUESDAY...
SATELLITE LOOP SHOWED SCATTERED CU DEVELOPING THIS AFTERNOON
ESPECIALLY ACROSS THE HIGHER TERRAIN. REGIONAL WSR-88D LOOP
DISPLAYED ISOLATED CONVECTION FORMING JUST SOUTHEAST OF CWA ACROSS
EASTERN PORTIONS OF VIRGINIA AND NORTH CAROLINA IN THE MOIST AND
UNSTABLE AIR. RNK WRF ARW AND RUC INDICATED THAT THE BEST CHANCE
FOR THUNDERSTORMS THIS AFTERNOON INTO TONIGHT WILL OCCUR ALONG THE
SOUTHERN BLUE RIDGE MOUNTAINS. THE NAM AND GFS FOCUS ON CONVECTION
THIS EVENING INTO TONIGHT IN THE WEST AND NORTHWEST. INCREASED POPS
THIS EVENING IN THE NORTHWEST ALLOWING FOR MENTION OF LIKELY FOR
SOUTHEAST WEST VIRGINIA WITH BEST SFC MOISTURE CONVERGENCE AND MID
LVL OMEGA FIELDS. SOME OF THE STORMS TONIGHT COULD CONTAIN HEAVY
DOWNPOURS...HAIL AND GUSTY WINDS. WITH THE LOSS OF SOLAR
HEATING...CONVECTION WILL WEAKEN AND TAPER OFF AFTER MIDNIGHT. WENT
WITH LOW TEMPERATURES CLOSE TO MILD ADJMAV WITH VALUES FROM THE MID
50S IN THE MOUNTAINS TO THE MID 60S IN THE SOUTHEAST. WARM AND HUMID
CONDITIONS CONTINUE ON WEDNESDAY IN THE SOUTHERLY FLOW OUT AHEAD OF
THE APPROACHING COLD FRONT AND UPPER TROUGH. INCREASED POPS FROM
WEST TO EAST ON WEDNESDAY...WITH HIGHEST POPS ALONG WESTERN
MOUNTAINS. THE SWODY2 (DAY TWO CONVECTIVE OUTLOOK) HAS THE SLIGHT
RISK JUST TO OUR WEST ON WEDNESDAY. PLAYED HIGHS TEMPERATURES COOLER
ON WEDNESDAY WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO
THE MID 80S IN THE SOUTHEAST.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 255 PM EDT TUESDAY...
HAVE A COUPLE DAYS MORE OF HUMID WEATHER BEFORE FRONT SWINGS ACROSS
THURSDAY AND BRINGS A RETURN TO LOWER DEWPOINTS.
UNTIL THEN...NO MAJOR CHANGES TO THE FORECAST. WEDNESDAY NIGHT A
PIECE OF SHORTWAVE ENERGY ARRIVES ACROSS THE CENTRAL APPALACHIANS
WHICH CREATES AN AREA OF SHOWERS AND STORMS...MAINLY AFFECTING THE
WRN EDGE OF THE FORECAST AREA. THE BETTER PUSH OF THE FRONT ON
THURSDAY COMBINED WITH BETTER UPPER SUPPORT SHOULD BRING SOME
ENHANCED THREAT OF SHOWERS AND STORMS. TIMING OF THIS FRONT DOES
VARY SOMEWHAT FROM THE MODELS BUT ENOUGH AGREEMENT TO HAVE HIGH
CHANCE TO LIKLEY IN THE AREA THURSDAY. TIMING ALSO GIVES ISSUES TO
SVR THREAT. ATTM...EXPECT A LINE OF SHRA/TSRA TO BE IN THE MTNS IN
THE MORNING AND MOVING INTO THE PIEDMONT BY EARLY AFTERNOON. NOT
SEEING A LOT OF HEATING AS CLOUDS WILL BE GENEROUSLY SPREAD. ONE
AREA WITH THE BETTER INSOLATION COULD BE SOUTHSIDE VA/NW NC
PIEDMONT. AT THIS TIME...THE STORM PREDICTION CENTER HAS A 5 PERCENT
THREAT OF SVR WX MAINLY OVER THE PIEDMONT AND TIDEWATER AREAS OF
VA/NC.
THE FRONT WILL BE EAST OF THE AREA GOING INTO THURSDAY EVENING WITH
LINGERING SHORTWAVE INDUCED SHOWERS ACROSS THE MTNS OVERNIGHT. THE
MAIN SHORTWAVE SHIFTS EAST BY 12Z FRIDAY WITH DRIER AND COOLER AIR
ARRIVING. HIGHS FRIDAY WILL RANGE FROM THE LOWER TO MID 60S WEST TO
THE LOWER TO MID 70S EAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY
FOR THE LONG RANGE FORECAST...THE MODELS KEEP A TROUGH IN PLACE
EARLY ON AND THEN GO MORE TOWARD A ZONAL TO RIDGE CONFIGURATION BY
THE END OF THE PERIOD.
WE SHOULD BE MAINLY DRY AS SFC HIGH BUILDS ACROSS THIS WEEKEND...SO
WEEKEND HOLIDAY PLANS ARE LOOKING GOOD FOR OUTDOOR ACTIVITIES AT
LEAST SATURDAY...AS THE LATEST ECMWF SHOWS ANOTHER WEAK SHORTWAVE
PUSHING ACROSS BY SUNDAY AND MAY BRING SOME SHOWERS ACROSS THE MTN
EMPIRE OF SW VA/INTO THE NC MTNS SUNDAY MORNING.
THE FLOW SWINGS MORE TOWARD THE SOUTHEAST SUNDAY EVENING INTO EARLY
NEXT WEEK WITH INCREASING HUMIDITY AND TEMPS. MODELS KEEPING MORE
ACTIVE WEATHER ACROSS THE OHIO VALLEY AND WEST...ALTHOUGH A WESTERLY
FLOW ALOFT CAN BRING STORMS WORKING EAST INTO THE MTNS. GIVEN WPC
SOLUTION OF THE ECMWF ENSEMBLE WILL KEEP THE FORECAST MORE ON THE
LOW CHANCE SIDE...BUT IF THE 12Z ECMWF VERIFIES WE COULD BE GETTING
SOAKED AGAIN MONDAY-WEDNESDAY.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 645 PM EDT TUESDAY...
CONVECTION REMAINS QUITE ISOLATED ACROSS THE REGION THIS EVENING
WITH MOST COVERAGE OVER NW NORTH CAROLINA WELL SW OF THE TAF
SITES. MAIN CONCERN WILL BE WITH THE COMPLEX OF SHRA/TSRA
ASSOCIATED WITH AN OLD OUTFLOW HEADING NE OUT OF TN/KY DURING THE
NEXT FEW HOURS. LATEST SHORT RANGE GUIDANCE BRINGS SOME OF THIS AS
FAR EAST AS THE BLUE RIDGE AROUND MIDNIGHT BEFORE IT FADES. THUS
MAY HAVE A STORM OR SHRA AFFECT KBLF/KLWB DURING THE LATE EVENING
...WITH A BAND/CLUSTER OF SHRA/TSRA NEAR KBCB/KROA TOWARD
MIDNIGHT PENDING HOW FAR EAST THE PRECIP MAKES IT AFTER LOSS OF
HEATING AND LITTLE UPPER SUPPORT. GIVEN UNCERTAINTY WILL COVER
MAINLY WITH VCTS/VCSH FOR NOW AND AMEND IF STORMS DO INDEED GET
CLOSER.
OTHER CONCERN AGAIN WITH FOG LATE ESPCLY NEAR WHERE ANY RAINFALL
OCCURS GIVEN SUCH A MUGGY ENVIRONMENT. LATEST FORECAST RAOB
SOUNDINGS SUGGEST QUITE A BIT OF PATCHY FOG BUT LIKELY NOT AS
WIDESPREAD AS THIS MORNING EXCEPT IN SPOTS WHERE A SHRA PASSES.
REGARDLESS OF SHRA COVERAGE...APPEARS KLWB STILL HAS THE BEST
CHANCE TO DROP TO LIFR IN FOG WEDNESDAY MORNING WITH A PERIOD OF
IFR ELSW EXCLUDING KBLF/KROA WHERE ONLY BRIEF MVFR POSSIBLE AT
THIS TIME.
EXPECT A QUICK IMPROVEMENT TO CONDITIONS ON WEDNESDAY WITH THE
ONSET OF HEATING AND DECENT MIXING BY MID OR LATE MORNING. THINK
ALL SITES WILL BE VFR BY 15Z/11AM BUT WITH A BETTER SHOT AT
AFTERNOON CONVECTION DEVELOPING ESPCLY WEST OF THE BLUE RIDGE BY
20Z/4PM. WITH POTENTIAL TO SEE A BAND OF SHRA/TSRA DEVELOP WESTERN
SLOPES...INCLUDED A PREVAILING -TSRA THREAT AT BOTH KBLF/KLWB
WEDNESDAY AFTERNOON WHILE LEAVING ELSW VFR W/OUT CONVECTION UNDER
SCTD/BKN 5-6K FT CU FIELDS.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY AHEAD
OF A COLD FRONT THAT SHOULD PUSH THROUGH LATE IN THE DAY THURSDAY.
THIS WILL BRING THE BEST COVERAGE OF SHOWERS WEDNESDAY NIGHT INTO
THURSDAY ALONG WITH AREAS OF LATE NIGHT/EARLY MORNING FOG.
HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE EXPECTED ON FRIDAY
AND THROUGH MUCH OF THE WEEKEND BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...WP
LONG TERM...WP
AVIATION...AMS/JH/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
317 PM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST INTO THE ATLANTIC THIS
EVENING INTO TONIGHT. A LARGE LOW PRESSURE SYSTEM WILL TRACK FROM
THE CENTRAL PLAINS INTO THE GREAT LAKES BY THURSDAY. THIS SYSTEM
WILL PUSH A COLD FRONT THROUGH THE AREA THURSDAY...FOLLOWED BY
HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 310 PM EDT TUESDAY...
SATELLITE LOOP SHOWED SCATTERED CU DEVELOPING THIS AFTERNOON
ESPECIALLY ACROSS THE HIGHER TERRAIN. REGIONAL WSR-88D LOOP
DISPLAYED ISOLATED CONVECTION FORMING JUST SOUTHEAST OF CWA ACROSS
EASTERN PORTIONS OF VIRGINIA AND NORTH CAROLINA IN THE MOIST AND
UNSTABLE AIR. RNK WRF ARW AND RUC INDICATED THAT THE BEST CHANCE
FOR THUNDERSTORMS THIS AFTERNOON INTO TONIGHT WILL OCCUR ALONG THE
SOUTHERN BLUE RIDGE MOUNTAINS. THE NAM AND GFS FOCUS ON CONVECTION
THIS EVENING INTO TONIGHT IN THE WEST AND NORTHWEST. INCREASED POPS
THIS EVENING IN THE NORTHWEST ALLOWING FOR MENTION OF LIKELY FOR
SOUTHEAST WEST VIRGINIA WITH BEST SFC MOISTURE CONVERGENCE AND MID
LVL OMEGA FIELDS. SOME OF THE STORMS TONIGHT COULD CONTAIN HEAVY
DOWNPOURS...HAIL AND GUSTY WINDS. WITH THE LOSS OF SOLAR
HEATING...CONVECTION WILL WEAKEN AND TAPER OFF AFTER MIDNIGHT. WENT
WITH LOW TEMPERATURES CLOSE TO MILD ADJMAV WITH VALUES FROM THE MID
50S IN THE MOUNTAINS TO THE MID 60S IN THE SOUTHEAST. WARM AND HUMID
CONDITIONS CONTINUE ON WEDNESDAY IN THE SOUTHERLY FLOW OUT AHEAD OF
THE APPROACHING COLD FRONT AND UPPER TROUGH. INCREASED POPS FROM
WEST TO EAST ON WEDNESDAY...WITH HIGHEST POPS ALONG WESTERN
MOUNTAINS. THE SWODY2 (DAY TWO CONVECTIVE OUTLOOK) HAS THE SLIGHT
RISK JUST TO OUR WEST ON WEDNESDAY. PLAYED HIGHS TEMPERATURES COOLER
ON WEDNESDAY WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO
THE MID 80S IN THE SOUTHEAST.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 255 PM EDT TUESDAY...
HAVE A COUPLE DAYS MORE OF HUMID WEATHER BEFORE FRONT SWINGS ACROSS
THURSDAY AND BRINGS A RETURN TO LOWER DEWPOINTS.
UNTIL THEN...NO MAJOR CHANGES TO THE FORECAST. WEDNESDAY NIGHT A
PIECE OF SHORTWAVE ENERGY ARRIVES ACROSS THE CENTRAL APPALACHIANS
WHICH CREATES AN AREA OF SHOWERS AND STORMS...MAINLY AFFECTING THE
WRN EDGE OF THE FORECAST AREA. THE BETTER PUSH OF THE FRONT ON
THURSDAY COMBINED WITH BETTER UPPER SUPPORT SHOULD BRING SOME
ENHANCED THREAT OF SHOWERS AND STORMS. TIMING OF THIS FRONT DOES
VARY SOMEWHAT FROM THE MODELS BUT ENOUGH AGREEMENT TO HAVE HIGH
CHANCE TO LIKLEY IN THE AREA THURSDAY. TIMING ALSO GIVES ISSUES TO
SVR THREAT. ATTM...EXPECT A LINE OF SHRA/TSRA TO BE IN THE MTNS IN
THE MORNING AND MOVING INTO THE PIEDMONT BY EARLY AFTERNOON. NOT
SEEING A LOT OF HEATING AS CLOUDS WILL BE GENEROUSLY SPREAD. ONE
AREA WITH THE BETTER INSOLATION COULD BE SOUTHSIDE VA/NW NC
PIEDMONT. AT THIS TIME...THE STORM PREDICTION CENTER HAS A 5 PERCENT
THREAT OF SVR WX MAINLY OVER THE PIEDMONT AND TIDEWATER AREAS OF
VA/NC.
THE FRONT WILL BE EAST OF THE AREA GOING INTO THURSDAY EVENING WITH
LINGERING SHORTWAVE INDUCED SHOWERS ACROSS THE MTNS OVERNIGHT. THE
MAIN SHORTWAVE SHIFTS EAST BY 12Z FRIDAY WITH DRIER AND COOLER AIR
ARRIVING. HIGHS FRIDAY WILL RANGE FROM THE LOWER TO MID 60S WEST TO
THE LOWER TO MID 70S EAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY
FOR THE LONG RANGE FORECAST...THE MODELS KEEP A TROUGH IN PLACE
EARLY ON AND THEN GO MORE TOWARD A ZONAL TO RIDGE CONFIGURATION BY
THE END OF THE PERIOD.
WE SHOULD BE MAINLY DRY AS SFC HIGH BUILDS ACROSS THIS WEEKEND...SO
WEEKEND HOLIDAY PLANS ARE LOOKING GOOD FOR OUTDOOR ACTIVITIES AT
LEAST SATURDAY...AS THE LATEST ECMWF SHOWS ANOTHER WEAK SHORTWAVE
PUSHING ACROSS BY SUNDAY AND MAY BRING SOME SHOWERS ACROSS THE MTN
EMPIRE OF SW VA/INTO THE NC MTNS SUNDAY MORNING.
THE FLOW SWINGS MORE TOWARD THE SOUTHEAST SUNDAY EVENING INTO EARLY
NEXT WEEK WITH INCREASING HUMIDITY AND TEMPS. MODELS KEEPING MORE
ACTIVE WEATHER ACROSS THE OHIO VALLEY AND WEST...ALTHOUGH A WESTERLY
FLOW ALOFT CAN BRING STORMS WORKING EAST INTO THE MTNS. GIVEN WPC
SOLUTION OF THE ECMWF ENSEMBLE WILL KEEP THE FORECAST MORE ON THE
LOW CHANCE SIDE...BUT IF THE 12Z ECMWF VERIFIES WE COULD BE GETTING
SOAKED AGAIN MONDAY-WEDNESDAY.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AS OF 130 PM EDT TUESDAY...
MORNING LOW CLOUDS AND FOG HAVE LIFTED ACROSS THE REGION.
SCT CU ARE FORMING THIS AFTERNOON ESPECIALLY ACROSS THE HIGHER
TERRAIN.
ONCE AGAIN...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
THIS AFTERNOON. THE BEST CHANCE OF A THUNDERSTORM IS ACROSS
THE WEST. LOCAL WRFARW DISPLAYED HIGHEST POPS ALONG THE SOUTHERN
BLUE RIDGE THIS AFTERNOON INTO TONIGHT. THEN...STORMS AND COVERAGE
TAPPER OFF OVERNIGHT INTO WEDNESDAY MORNING.
PATCHY FOG EXPECTED OVERNIGHT...IN LOCATIONS WHICH RAIN THIS
AFTERNOON AND THEN CLEAR OUT DURING THE EVENING INTO TONIGHT.
LWB HAS THE BEST CHANCE TO DROP TO LIFR IN FOG WEDNESDAY
MORNING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/KK
NEAR TERM...AMS/KK
SHORT TERM...WP
LONG TERM...WP
AVIATION...AMS/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
140 PM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST INTO THE ATLANTIC THIS
AFTERNOON INTO TONIGHT. A LARGE LOW PRESSURE SYSTEM WILL TRACK
FROM THE CENTRAL PLAINS INTO THE GREAT LAKES BY THURSDAY. THIS
SYSTEM WILL PUSH A COLD FRONT THROUGH THE AREA THURSDAY...FOLLOWED
BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM EDT TUESDAY...
NORTHWEST WINDS COMBINED WITH SUNSHINE WILL ALLOW VISIBILITIES TO
IMPROVE THIS MORNING...THUS THE DENSE FOG FOR WIDESPREAD HAS
ENDED. POCKET OF FOG MAY LINGER A HOUR OR SO IN THE DEEPER
SHELTERED LOCATION. SHORTWAVE OVER SOUTHSIDE THIS MORNING WILL
TRAVEL EAST INTO EASTERN VIRGINIA THIS AFTERNOON. RUC AND WRF
INDICATED THAT THE BEST CHANCE FOR THUNDERSTORMS THIS AFTERNOON
WILL BE ALONG THE SOUTHERN BLUE RIDGE. MADE SOME MINOR
ADJUSTMENTS IN TEMPERATURES AND DEW POINTS.
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 130 PM EDT TUESDAY...
MORNING LOW CLOUDS AND FOG HAVE LIFTED ACROSS THE REGION.
SCT CU ARE FORMING THIS AFTERNOON ESPECIALLY ACROSS THE HIGHER
TERRAIN.
ONCE AGAIN...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
THIS AFTERNOON. THE BEST CHANCE OF A THUNDERSTORM IS ACROSS
THE WEST. LOCAL WRFARW DISPLAYED HIGHEST POPS ALONG THE SOUTHERN
BLUE RIDGE THIS AFTERNOON INTO TONIGHT. THEN...STORMS AND COVERAGE
TAPPER OFF OVERNIGHT INTO WEDNESDAY MORNING.
PATCHY FOG EXPECTED OVERNIGHT...IN LOCATIONS WHICH RAIN THIS
AFTERNOON AND THEN CLEAR OUT DURING THE EVENING INTO TONIGHT.
LWB HAS THE BEST CHANCE TO DROP TO LIFR IN FOG WEDNESDAY
MORNING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS/KK
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1151 AM CDT TUE MAY 21 2013
.AVIATION/18Z TAFS/...LIMITED CONVECTIVE POTENTIAL WITH LACK OF
FORCING AND DRY AIR ADVECTION IN LOW LEVELS AS WINDS START TO
SHIFT SW. ISOLATED DEVELOPMENT NORTH OF THE CWA WILL CONTINUE TO
PULL AWAY TO THE NE. THIS WAS IN AGREEMENT WITH LATEST HRRR RUN.
EVERYTHING PRETTY MUCH SHUTS DOWN WITH CU FIELD FILLING IN FROM
IA AND NW IL. SOME CEILINGS ARE MVFR WITHIN THIS CLOUD FIELD. MORE
SHRA AND LOWER CEILINGS ON WEDNESDAY AS LOW DEVELOPS AND MOVES TO
OUR SOUTH AND EAST.
PC
&&
.PREV DISCUSSION... /ISSUED 537 AM CDT TUE MAY 21 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM
AREAS OF STRATUS WILL PREVAIL EARLY THIS MORNING WITH SOME CLEARING
BY MID TO LATE MORNING. THIS WILL AID DAYTIME HEATING AND
INSTABILITY FOR LATE THIS MORNING AND AFTERNOON. VARIOUS MODEL
SOUNDINGS VARY WITH EXPECTED CAPE VALUES FROM VERY LITTLE UP TO 1000
J/KG. THIS HAS TO DO WITH DIFFERENCES IN MID LEVEL LAPSE RATES AND
DEWPOINTS. WILL COUNT ON MARGINAL CAPE PERHAPS UP TO 500 J/KG.
TRIGGERS FOR CONVECTION TODAY ARE WEAK WITH A COUPLE WEAK VORTICITY
MAXIMUMS TO SWING NWD IN THE SLY FLOW ALOFT OF THE UPPER LOW. A WEAK
SFC TROUGH MAY ALSO BECOME PRESENT AS SLY WINDS TURN MORE WLY. WILL
GO WITH CHANCES OF TSTORMS FROM LATE AM THROUGH THE AFTERNOON. LOW
PROBABILITIES OF SEVERE WX WILL BE POSSIBLE GIVEN MDT DEEP LAYER
SHEAR AND MID LEVEL DRY AIR.
THE UPPER LOW WILL FINALLY BEGIN TO MOVE SEWD INTO WRN IA BY 12Z
WED. THE FORWARD TILT UPPER TROUGH WILL BECOME MORE NEGATIVE TILT
WITH SATURATION AND RAIN POSSIBLE IN FAR SE WI BY 12Z.
WEDNESDAY AND WEDNESDAY NIGHT...FORECAST CONFIDENCE MEDIUM.
THE STACKED LOW PRESSURE SYSTEM FINALLY SLIDES INTO THE AREA ON
WEDNESDAY AND PASSES OVERHEAD WEDNESDAY NIGHT. THERE IS IMPRESSIVE
AND RATHER SUSTAINED Q-VECTOR CONVERGENCE THROUGH THE PERIOD WITH
DEEP MOISTURE AVAILABLE. THIS LOOKS LIKE OUR BEST CHANCE FOR A
WIDESPREAD RAINFALL. INSTABILITY IS MARGINAL SO WILL JUST CARRY A
CHANCE FOR STORMS. NO SEVERE WEATHER IS EXPECTED.
WINDS ALSO TURN ONSHORE ACROSS THE SOUTHEAST...SO AREAS CLOSE TO
THE LAKE WILL COOL OFF QUITE A BIT.
THURSDAY AND THURSDAY NIGHT...FORECAST CONFIDENCE IS HIGH.
WILL LINGER A CHANCE FOR RAIN ACROSS THE SOUTHEAST THURSDAY
MORNING AS THE REMNANTS OF THE UPPER LOW PULL AWAY. THEN MUCH
COOLER AND DRIER WEATHER OVERSPREADS THE AREA ON INCREASING
NORTHEAST WINDS AS HIGH PRESSURE BUILDS IN. WE COULD SEE LOWS
THURSDAY NIGHT DIP INTO THE UPPER 30S IN MANY AREAS AS WINDS FALL
OFF WITH THE RIDGE AXIS MOVING OVERHEAD.
FRIDAY AND FRIDAY NIGHT...
COOL AND DRY FOR FRIDAY WITH HIGH PRESSURE HOLDING STRONG.
AS THE RIDGE SLIDES OFF TO THE EAST FRIDAY NIGHT...THE RETURN FLOW
WARM AIR ADVECTION COULD BRING IN SOME LATE NIGHT THUNDERSTORMS.
THIS IS A PRETTY SMALL CHANCE AT THIS POINT.
SATURDAY AND BEYOND...FORCAST CONFIDENCE IS LOW TO MEDIUM.
THE GFS AND THE ECMWF ARE IN DISAGREEMENT WITH THE PATTERN THIS
WEEKEND INTO EARLY NEXT WEEK. THE ECMWF MAINTAINS THE RIDGE OVER
OUR AREA AND THE GREAT LAKES THROUGH NEXT TUESDAY...RESULTING IN
DRY WEATHER. MEANWHILE THE GFS PUSHES A SFC BOUNDARY FARTHER
EAST...ACTING AS A FOCUS FOR SHOWERS AND STORMS THROUGH THE SAME
PERIOD. A BLEND WOULD KEEP ANY RISK FOR STORMS MAINLY OVER OUR FAR
WESTERN CWA...AND THOSE CHANCES LOOK SMALL.
AVIATION/12Z TAFS/...IFR TO MVFR STRATUS HAS FORMED OVER SRN WI AND
SWWD INTO ERN IA. THIS STRATUS WILL LIKELY NOT DISSIPATE UNTIL MID
TO LATE MORNING FOR KMSN. A MUCH LESSER TIME PERIOD OF STRATUS IS
EXPECTED OVER THE SE WI TAF SITES. THE STRATUS SHOULD LIFT INTO
SCT-BKN CUMULUS CONGESTUS OF 4-5 KFT FOR THE AFTERNOON. A WEAK WIND
SHIFT LINE WILL GRADUALLY SHIFT WINDS FROM SLY TO WLY TODAY. THERE
IS A CHANCE OF TSTORMS MAINLY THIS AFTERNOON AS THE WINDS SHIFT.
DRIER AIR WILL ARRIVE ON THE WLY WINDS FOR TNT BUT LOW PRESSURE OVER
IA WILL BRING GOOD CHANCES OF RAIN TO FAR SRN WI INCLUDING KENW
TOWARD SUNRISE WED AM. AREAS OF LIGHT FOG COULD DEVELOP LATE TNT
BEFORE THE CLOUDS AND RAIN CHANCES MOVE BACK INTO THE AREA.
WIDESPREAD RAIN WITH LOW CIGS AND VSBYS IS THEN EXPECTED ON WED.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...GEHRING
WEDNESDAY THROUGH MONDAY...DAVIS