Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/19/13
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
900 AM MST FRI MAY 17 2013
.SYNOPSIS...
A DRY PACIFIC COLD FRONT WILL MOVE ACROSS THE AREA
TODAY...ACCOMPANIED BY BRIEF CLOUDINESS...GUSTY AFTERNOON
WINDS...AND COOLER TEMPERATURES. A SLIGHTLY COOLER AIRMASS WILL
SETTLE INTO THE REGION SATURDAY PROVIDING CLEAR SKIES WITH BELOW
NORMAL TEMPERATURES. A WARMING TREND IS EXPECTED SUNDAY...WITH
AFTERNOON TEMPERATURES WARMING BACK INTO 100 TO 103 DEGREE RANGE ON
THE DESERTS NEXT MONDAY THROUGH THURSDAY.
&&
.DISCUSSION...
MID MORNING WATER VAPOR IMAGERY DEPICTS A TROUGH STRETCHING FROM
BRITISH COLUMBIA TO BAJA CALIFORNIA...WITH QUITE A BIT OF MID LEVEL
MOISTURE MOVING INTO SOUTHERN CALIFORNIA...ARIZONA...AND UTAH. CLOUD
COVER HAS REALLY EXPANDED OVER THE PAST SEVERAL HOURS AS A 70KT
UPPER JET HAS MOVED ONSHORE...LIKEWISE...PRECIPITABLE WATER PER
BLENDED TPW IMAGERY HAS INCREASED AND IS NOW CLOSE TO 0.8 INCHES
ALONG THE LOWER COLORADO RIVER VALLEY /APPROX 150 PERCENT OF
NORMAL/. NOT SURPRISINGLY...RADAR BEGINNING TO SHOW SOME RETURNS
ACROSS SOUTHEAST CALIFORNIA INTO WESTERN ARIZONA...HOWEVER SURFACE
DEWPOINTS REMAIN IN THE LOW TO MID 40S.
WITH DEWPOINTS FORECAST TO DROP SEVERAL MORE DEGREES LATER THIS
AFTERNOON...HARD TO ENVISION MUCH /IF ANY/ MEASURABLE PRECIP WITH
THIS TROUGH. 12Z NAM MODEL SOUNDINGS AND 14Z RAP DATA...ALONG WITH
LATEST HRRR RUN AND HI-RES LOCAL MODEL SUITE INDICATE A CONSIDERABLE
T/TD SPREAD BELOW 700MB ACROSS THE LOWER DESERTS ALL THE WAY THROUGH
THIS EVENING. I INTRODUCED A CHANCE OF SPRINKLES INTO THE FORECAST
FOR THE HIGHER ELEVATIONS OF SOUTHEAST CALIFORNIA AND SOUTH-CENTRAL
ARIZONA THROUGH LATE AFTERNOON...BUT POPS WILL REMAIN AT 0. EVEN THE
NORMALLY PESSIMISTIC SREF ADVERTISES 0 POPS ACROSS THE FORECAST AREA
TODAY. WILL BE DIFFICULT TO OVERCOME THE VERY DRY BL. SOME
BREEZINESS IS EXPECTED WITH THE TROUGH LATER THIS AFTERNOON COURTESY
OF MODEST DRY ADVECTION. THE STRONGEST WINDS /30 MPH GUSTS/ WILL BE
CONFINED TO THE NORMALLY WINDIER LOCATIONS OF SOUTHEAST CALIFORNIA
AND THE LOWER COLORADO RIVER VALLEY ALTHOUGH CRITICAL FIRE WX/WIND
ADVISORY THRESHOLDS SHOULD NOT BE REALIZED.
TEMPS TODAY LOOKING ON TRACK SO FAR. BEST PERFORMING BIAS CORRECTED
GUIDANCE SQUARELY POINTING AT 96 FOR A HIGH IN PHOENIX WITH SLIGHTLY
COOLER VALUES TO THE WEST. SHOULD BE THE FIRST DAY SINCE SUNDAY
BELOW THE CENTURY MARK. ONLY MINOR ADJUSTMENTS MADE TO THE INHERITED
TEMPERATURE FORECAST.
&&
.PREVIOUS DISCUSSION...
SATURDAY THROUGH MONDAY...
DRY NORTHWEST FLOW ALOFT WITH NEARLY CLOUDLESS SKIES ARE EXPECTED
THIS PERIOD. ADDITIONAL COOLING IS FORECAST FOR SATURDAY...WARMING
SUNDAY...THEN BACK INTO THE 100 TO 103 DEGREE RANGE ON THE DESERTS
MONDAY.
TUESDAY THROUGH THURSDAY...
DRY WESTERLY FLOW ALOFT WITH ABOVE NORMAL TEMPERATURES ARE EXPECTED.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...KSDL...SOUTHEAST
CALIFORNIA/SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH...
A LOW PRESSURE TROUGH WILL SKIRT BY TO THE NORTH TODAY WITH
INCREASED MID AND HIGH CLOUDS THROUGH THE EVENING. SOME LATE
AFTERNOON BREEZINESS CAN BE EXPECTED WITH GUSTS AROUND 20-25KTS
/POSSIBLY AROUND 30KTS AT BLH AND IPL/...OTHERWISE WINDS WILL BE
LIGHT AND WILL FAVOR TYPICAL DIURNAL PATTERNS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
PRETTY QUIET WEATHER EXPECTED NEXT WEEK. SOME LOCALIZED BREEZINESS
IS POSSIBLE MONDAY AND TUESDAY AFTERNOONS AS A TROUGH MOVES THROUGH
UTAH AND ARIZONA...BUT WINDS SHOULD REMAIN AT OR BELOW 20MPH. WINDS
ARE LIKELY TO REMAIN ON THE LIGHT SIDE THEREAFTER AS HIGH PRESSURE
SETTLES OVERHEAD. HUMIDITIES WILL REMAIN LOW THROUGH THE
PERIOD...WITH MINIMUM RELATIVE HUMIDITIES DROPPING INTO THE SINGLE
DIGITS EACH DAY WITH FAIR OVERNIGHT RECOVERY EXPECTED.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...LEINS/VASQUEZ
AVIATION...KUHLMAN
FIRE WEATHER...LEINS/KUHLMAN
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
335 PM PDT FRI MAY 17 2013
.SHORT TERM DISCUSSION...
UPPER LEVEL TROUGH IS MOVING EAST INTO THE GREAT BASIN THIS
AFTERNOON. CONVECTION HAS NOT MATERIALIZED THUS FAR THIS AFTERNOON
MUCH AS THE HRRR HAS PREDICTED. THE MAIN SUPPRESSOR SEEMS TO BE
WARMING ABOVE 8000 FEET WHICH HAS CAPPED THE ATMOSPHERE. DELTA
BREEZE HAS DEVELOPED WITH WINDS GUSTING TO 30 MPH OVER THE DELTA.
TROUGH WILL CONTINUE EAST TONIGHT WITH DRIER AIR FILTERING INTO
NORCAL PROVIDING CLEAR SKIES.
UPPER RIDGE WILL BUILD INTO NORCAL TOMORROW WITH A DRY NORTHWEST
FLOW DEVELOPING. TEMPERATURES WILL WARM INTO THE LOW TO MID 80`S
FOR VALLEYS. WEAK DISTURBANCE PASSING THROUGH OREGON AND
WASHINGTON WILL BRUSH THE NORTHERN MOUNTAINS LATE IN THE AFTERNOON
WITH SOME INCREASED CLOUD COVER. ALSO ADDED SLIGHT SHOWER CHANCES
OVER THE NRN SIERRA NEAR LASSEN.
UPPER TROUGH WILL DEEPEN OVER THE ROCKIES ON SUNDAY WITH GUSTY
NORTH WINDS DEVELOPING ON THE BACKSIDE OF THIS FEATURE OVER THE
SAC VALLEY. GUSTS UP TO 35 MPH WILL BE POSSIBLE AND WIND ADVISORY
MAY BE NEEDED IF WIND FORECAST CONFIDENCE INCREASES. TEMPERATURES
WILL WARM INTO THE MID-UPPER 80`S FOR VALLEY LOCATIONS. RIDGE WILL
STRENGTHEN ON MONDAY WITH TEMPS WARMING INTO THE LOW 90`S AT MOST
VALLEY LOCATIONS.
.EXTENDED DISCUSSION (TUESDAY THROUGH FRIDAY)
A CLOSED UPPER-LEVEL LOW WITH REACH THE PACIFIC NW BY THE MIDDLE
OF NEXT WEEK. BASED ON PREDICTABILITY AND ENSEMBLE PLOTS...MODELS
ARE SHOWING A HIGH DEGREE OF CERTAINTY IN THIS FEATURE. THE MAIN
EFFECT FOR OUR AREA WILL BE COOLER TEMPERATURES...WITH PERHAPS
SOME SHOWERS FROM SHASTA COUNTY NORTHWARD. FIRST CHANCE WOULD BE
TUESDAY NIGHT AS THE INITIAL WAVE AT THE BASE OF THE LOW BRUSHES
OUR NORTHERN REACHES. SLIGHT CHANCES LINGER THROUGH
THURSDAY...BEFORE A SECONDARY WAVE TAKES AIM AT NORCAL. THIS IS
WHERE MODELS DIVERGE. THE 12Z ECMWF CHANGED SIGNIFICANTLY FROM THE
00Z SOLUTION...NOW TRENDING TOWARDS A PROGRESSIVE LOW AFFECTING
OUR AREA NORTH OF I80 THURSDAY NIGHT THEN QUICKLY LIFTING EASTWARD
(THE 00Z HAD AN SLOWER CLOSED LOW CENTERED RIGHT OVER SAC BY
FRIDAY). THE GFS MEANWHILE IS LESS PROGRESSIVE...AND DIGS A DEEPER
TROUGH ALONG THE WEST COAST FROM FRIDAY INTO THE WEEKEND. OVERALL
MESSAGE IS COOLER TEMPERATURES WITH A CHANCE OF RAIN SHOWERS OVER
THE MOUNTAINS. -DVC
&&
.AVIATION...
VFR CONDITIONS CONTINUE OVER INTERIOR NORCAL TAF SITES NEXT 24
HOURS. A WEAK LOW PRESSURE SYSTEM WILL BRUSH TO THE NORTH OF THE
AREA TOMORROW AFTERNOON...WITH THE ONLY EFFECT BEING A FEW MID-
LEVEL CLOUDS FROM AROUND KRBL NORTH. GENERALLY LIGHT WINDS EXPECTED
THROUGH THE PERIOD. -DVC
&&
.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PUEBLO CO
811 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 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 502 PM MDT SAT MAY 18 2013
UPPER LEVEL TROF WILL MOVE ACROSS SOUTHERN COLORADO OVER THE NEXT
24 HOURS. AT THE SURFACE...GUSTY WESTERLY WINDS WILL CONTINUE
THRU 03Z OVER THE SOUTHEAST PLAINS OF COLORADO AS SURFACE LOW
MOVES INTO WESTERN KS OVERNIGHT. A COLD FRONT WILL MOVE SOUTH
ACROSS THE SOUTHEAST PLAINS TONIGHT WITH WINDS SHIFTING TO THE
NORTH. VFR CONDITIONS SHOULD CONTINUE DURING THE NEXT 24
HOURS...HOWEVER SHOWERS AND THUNDERSTORMS WILL BE WIDELY SCATTERED
AFT 15Z. 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 DENVER/BOULDER CO
1049 AM MDT FRI MAY 17 2013
.UPDATE...
&&
.SHORT TERM...DRY AND VERY WARM AIR HAS SPREAD OVER THE FORECAST
AREA TODAY IN ADVANCE OF AN ABNORMALLY STRONG UPPER LEVEL TROUGH
CURRENTLY MOVING VERY SLOWLY EASTWARD OVER THE GREAT BASIN.
HOWEVER...LATER THIS AFTERNOON AND EVENING...A WARM AND MOIST
SOUTHEAST WIND ON THE PLAINS MAY CREATE CONDITIONS SUFFICIENTLY
UNSTABLE TO PRODUCE A FEW STRONG AND POSSIBLY SEVERE
THUNDERSTORMS IN THE NORTHEAST CORNER OF THE STATE. HAIL AROUND
ONE INCH IN DIAMETER AND WIND GUSTS TO AROUND 60 MPH WILL BE THE
PRINCIPLE THREAT. RAINFALL FROM THESE RELATIVELY FAST MOVING
STORMS IS NOT EXPECTED TO RESULT IN FLOODING. THIS LIMITED
THUNDERSTORM ACTIVITY SHOULD EXIT THE STATE BY AROUND MID-
EVENING. OTHERWISE...TEMPERATURES ALREADY RUNNING QUITE WARM.
TEMPERATURE READINGS AS OF 16Z WERE RUNNING 3 TO 9 DEG F ABOVE
THOSE OBSERVED 24 HOURS AGO. AT THIS PACE UNDER GENERALLY CLEAR
SKIES...COULD SEE MAX TEMPERATURES IN MANY AREAS NEARING IF NOT
EXCEEDING RECORDS FOR THIS DATE. IT`S ALREADY 83 AT DIA. RECORD
HIGH FOR DENVER IS 91 DEGS. COULD COME REAL CLOSE.
.AVIATION...VFR CONDITIONS ANTICIPATED NEXT 24 HOURS. WEST-
SOUTHWEST WINDS OF 7-14 KTS AT DENVER AREA AIRPORTS THROUGH MID-
AFTERNOON. THEN WEST-NORTHWEST WINDS AT SIMILAR SPEEDS THROUGH
EARLY THIS EVENING. THEN OVERNIGHT LOOK FOR A RETURN TO TYPICAL
DRAINAGE WINDS OF 5-11 KTS.
&&
.HYDROLOGY...ABNORMALLY WARM TEMPERATURES TODAY WILL ACCELERATE
SNOWMELT IN THE HIGH COUNTRY. THE RESULTING INCREASED RUNOFF MAY
CAUSE MINOR RISES ON SMALL CREEKS AND STREAMS. HOWEVER...WATER
LEVELS SHOULD REMAIN WELL BELOW FLOOD STAGE.
&&
.PREV DISCUSSION... /ISSUED 407 AM MDT FRI MAY 17 2013/
SHORT TERM...DRIER AIR IN INCREASING SOUTHWEST FLOW ALOFT WILL
SPREAD ACROSS THE AREA TODAY. AT THE SFC LOW PRESSURE WILL EXTEND
FM SERN WY INTO ERN CO WITH INCREASING SLY WINDS BY AFTN OVER THE
NERN PLAINS. LATE AFTN CAPES WILL RANGE FM 1500-2000 J/KG OVER THE
FAR NERN CORNER EAST OF A STERLING TO LIMON LINE. SOUNDINGS SHOW
CAP ERODING AFTER 22Z SO COULD SEE SOME ISOLD STORMS THRU 03Z.
WITH FAVORABLE SHEAR PROFILE IF A FEW STORMS DO DVLP THEY COULD
BECOME SVR. OTHERWISE IT WILL BE DRY OVER THE REST OF THE AREA
WITH AFTN HIGHS WELL ABV NORMAL. CURRENT 850-700 MB TEMPS WOULD
SUPPORT HIGHS IN THE UPPER 80S TO LOWER 90S ACROSS MOST OF NERN
CO. RECORD HIGH AT DENVER IS 91 SO IT COULD GET CLOSE THIS AFTN.
LONG TERM...NO CHANGES TO THE FORECAST THINKING THROUGH THE
WEEKEND AND INTO NEXT WEEK. MODELS CONTINUE TO SHOW A SLOWLY
EVOLVING UPPER AIR PATTERN THAT FEATURES A BROAD UPPER TROUGH
SETTLING OVER THE STATE SATURDAY AFTERNOON AND THEN TAKING TIL
TUESDAY TO MOVE ON TO THE NORTHERN PLAINS. WHILE THE UPPER TROUGH
LAGS OVER THE STATE...COOLER AND SOMEWHAT UNSETTLED WEATHER WILL
PREVAIL WITH PERIODS OF SHOWERS AND POSSIBLY SOME EMBEDDED
THUNDERSTORMS ACROSS THE FORECAST AREA. DYNAMIC FORCING WITH THE
UPPER TROUGH WILL NOT BE ALL THAT STRONG...SO PRECIPITATION
AMOUNTS LOOK LIKE THEY WILL ONLY BE LIGHT TO MODERATE. THE COOLEST
DAY OF THE SET APPEARS TO BE MONDAY...WITH A GRADUAL WARMING TREND
EXPECTED THROUGH THE REMAINDER OF NEXT WEEK. THE COOLER THAN
NORMAL TEMPERATURES ALONG WITH PERIODS OF LIGHT RAIN SHOULD HELP
THE SPRING VEGETATION STAY GREEN FOR A LITTLE LONGER.
AVIATION...VFR THRU TONIGHT. SLY WIND EARLY THIS MORNING MAY
BECOME MORE SWLY BY 14Z. BY 18Z THE RAP HAS THE WINDS STAYING SSW
WHILE THE NAM IS MORE WLY. BY 21Z BOTH MODELS SHOW THE WNDS SSW.
FOR NOW WILL KEEP THEM SSW THRU THE AFTN. FOR TONIGHT WILL KEEP
THE WINDS DRAINAGE OVERNIGHT.
HYDROLOGY...NO ISSUES.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BAKER/RPK
LONG TERM....DANKERS
AVIATION...BAKER/RPK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
407 AM MDT FRI MAY 17 2013
.SHORT TERM...DRIER AIR IN INCREASING SOUTHWEST FLOW ALOFT WILL
SPREAD ACROSS THE AREA TODAY. AT THE SFC LOW PRESSURE WILL EXTEND
FM SERN WY INTO ERN CO WITH INCREASING SLY WINDS BY AFTN OVER THE
NERN PLAINS. LATE AFTN CAPES WILL RANGE FM 1500-2000 J/KG OVER THE
FAR NERN CORNER EAST OF A STERLING TO LIMON LINE. SOUNDINGS SHOW
CAP ERODING AFTER 22Z SO COULD SEE SOME ISOLD STORMS THRU 03Z.
WITH FAVORABLE SHEAR PROFILE IF A FEW STORMS DO DVLP THEY COULD
BECOME SVR. OTHERWISE IT WILL BE DRY OVER THE REST OF THE AREA
WITH AFTN HIGHS WELL ABV NORMAL. CURRENT 850-700 MB TEMPS WOULD
SUPPORT HIGHS IN THE UPPER 80S TO LOWER 90S ACROSS MOST OF NERN
CO. RECORD HIGH AT DENVER IS 91 SO IT COULD GET CLOSE THIS AFTN.
.LONG TERM...NO CHANGES TO THE FORECAST THINKING THROUGH THE
WEEKEND AND INTO NEXT WEEK. MODELS CONTINUE TO SHOW A SLOWLY
EVOLVING UPPER AIR PATTERN THAT FEATURES A BROAD UPPER TROUGH
SETTLING OVER THE STATE SATURDAY AFTERNOON AND THEN TAKING TIL
TUESDAY TO MOVE ON TO THE NORTHERN PLAINS. WHILE THE UPPER TROUGH
LAGS OVER THE STATE...COOLER AND SOMEWHAT UNSETTLED WEATHER WILL
PREVAIL WITH PERIODS OF SHOWERS AND POSSIBLY SOME EMBEDDED
THUNDERSTORMS ACROSS THE FORECAST AREA. DYNAMIC FORCING WITH THE
UPPER TROUGH WILL NOT BE ALL THAT STRONG...SO PRECIPITATION
AMOUNTS LOOK LIKE THEY WILL ONLY BE LIGHT TO MODERATE. THE COOLEST
DAY OF THE SET APPEARS TO BE MONDAY...WITH A GRADUAL WARMING TREND
EXPECTED THROUGH THE REMAINDER OF NEXT WEEK. THE COOLER THAN
NORMAL TEMPERATURES ALONG WITH PERIODS OF LIGHT RAIN SHOULD HELP
THE SPRING VEGETATION STAY GREEN FOR A LITTLE LONGER.
&&
.AVIATION...VFR THRU TONIGHT. SLY WIND EARLY THIS MORNING MAY
BECOME MORE SWLY BY 14Z. BY 18Z THE RAP HAS THE WINDS STAYING SSW
WHILE THE NAM IS MORE WLY. BY 21Z BOTH MODELS SHOW THE WNDS SSW.
FOR NOW WILL KEEP THEM SSW THRU THE AFTN. FOR TONIGHT WILL KEEP
THE WINDS DRAINAGE OVERNIGHT.
&&
.HYDROLOGY...NO ISSUES.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS MIAMI FL
229 PM EDT FRI MAY 17 2013
.DISCUSSION...
A WEAK AREA OF LOW PRESSURE REMAINS OVER SOUTH FLORIDA EARLY THIS
AFTERNOON...AND THIS FEATURE WILL DRIFT TO THE WEST AND PUSH OUT
INTO THE GULF OF MEXICO LATER TONIGHT. THIS WILL BRING SOME
SUBSIDENCE TO THE WESTERN HALF OF THE REGION...SO REMOVED THE POPS
FOR THE NAPLES AREA THIS AFTERNOON. SHOWERS THAT HAVE FORMED HAVE
HAD HIGH BASES...WHICH INDICATES THERE IS STILL DRY AIR IN THE LOW
LEVELS. WATER VAPOR IMAGERY INDICATES DRIER MID LEVEL AIR IS MOVING
IN FROM THE NORTHWEST...AND THE DRIER AIR IN THE LOW AND MID LEVELS
SHOULD PREVENT MANY...IF ANY THUNDERSTORMS THIS AFTERNOON. THE GFS
HAS BACKED OFF ON ANY SHOWERS THIS AFTERNOON...EXCEPT FOR PALM BEACH
COUNTY WHERE THEY WERE OCCURRING. THE HRRR STILL SHOWED ISOLATED TO
SCATTERED SHOWERS ALONG THE EAST COAST SEA BREEZE AFTER 20-21Z. SO
LEFT THE ISOLATED TO SCATTERED SHOWERS AND SLIGHT CHANCE OF THUNDER
WORDING. ANY SHOWERS OR STORMS THAT DEVELOP MAY CONTINUE INTO THE
EARLY EVENING BEFORE DISSIPATING.
AN UPPER RIDGE STRETCHING FROM TEXAS THROUGH THE NORTHERN PLAINS
WILL SLOWLY SHIFT EAST THROUGH THE WEEKEND. A WEAK SHORTWAVE WILL
DIVE SOUTHEAST SATURDAY AFTERNOON ACROSS FLORIDA IN THE
NORTHWESTERLY FLOW ALOFT. TEMPERATURES ALOFT ARE EXPECTED TO COOL TO
-10 TO -11C WITH 25-30 KNOTS OF 0-6KM BULK SHEAR. LAPSE RATES ALOFT
ARE NOT THAT IMPRESSIVE AND THERE IS STILL DRY AIR IN THE LOW/MID
LEVELS. HOWEVER...A COUPLE STRONG STORMS CANNOT BE RULED OUT ALONG
THE SEA BREEZE BOUNDARIES...MAINLY ACROSS THE INTERIOR. STORM MOTION
WILL BE DEPENDENT ON THE SEA BREEZE AND OUTFLOW BOUNDARIES. HIGHS ON
SATURDAY WILL BE NEAR NORMAL IN THE MID 80S TO LOWER 90S.
TEMPS WILL WARM ALOFT A BIT ON SUNDAY...AND SLIGHTLY DRIER AIR WILL
MOVE IN FROM THE EAST. SO THE EAST COAST SHOULD REMAIN MAINLY DRY
EXCEPT FOR POSSIBLY A FEW MORNING SHOWERS...WITH ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE INTERIOR AND GULF
COAST.
AN UPPER TROUGH WILL PUSH INTO THE INTERMOUNTAIN WEST ON SUNDAY AND
INTO THE NORTHERN PLAINS ON MONDAY...AND HIGH PRESSURE WILL SHIFT TO
THE EAST. THE LOW LEVEL FLOW WILL BEGIN TO SHIFT TO THE
SOUTHEAST...WITH SLIGHTLY DEEPER MOISTURE BEGINNING TO MOVE INTO THE
REGION. THE HIGHEST POPS WILL REMAIN OVER THE INTERIOR AND GULF
COAST. A WEAK UPPER TROUGH/LOW WILL PUSH SOUTHEAST INTO THE WESTERN
ATLANTIC BY SUNDAY AS IT GETS TRAPPED BENEATH A RIDGE OF HIGH
PRESSURE. THIS FEATURE IS EXPECTED TO THEN RETROGRADE SLOWLY TO THE
WEST SOUTHWEST THROUGH THE MIDDLE OF THE WEEK. IF THIS TROUGH MOVES
AS THE GFS INDICATES...DEEP SOUTHEASTERLY FLOW WOULD PREVAIL ON
TUESDAY...WITH TROPICAL MOISTURE MOVING INTO SOUTH FLORIDA. THE
ECMWF IS SLIGHTLY SLOWER AND PUSHES THE WEAK UPPER TROUGH/LOW OVER
DEEP SOUTH FLORIDA OR THE WESTERN GULF ON WEDNESDAY...DELAYING THE
DEEP MOISTURE UNTIL THAT TIME. EITHER WAY...IT APPEARS THAT DEEP
MOISTURE WILL MOVE OVER SOUTH FLORIDA BY THE MIDDLE OF THE WEEK AND
REMAIN THROUGH THE END OF THE FORECAST PERIOD.
&&
.AVIATION...
WEAK LOW PRESSURE NORTH OF KPBI FOCUSED SHOWERS THIS MORNING IN THAT
AREA, BUT WITH THE LOW MOVING TO THE NORTH THIS AFTERNOON, EXPECT
SHOWERS/ISOLATED TSTMS TO BE CONCENTRATED OVER THE INTERIOR WITH VFR
CONDITIONS AND VCSH FOR THE EAST COAST SITES. KAPF SHOULD SEE NO
MORE THAN A FEW CLOUDS WITH GULF SEA BREEZE THIS AFTERNOON. QUIET
NIGHT EXPECTED WITH ISOLATED SHOWERS AT WORST ALONG THE E COAST AND
PATCHY INLAND FOG. SE FLOW ON SATURDAY CONTINUING TO BRING IN A FEW
SHOWERS MAINLY E COAST WITH VFR PREVAILING.
&&
.MARINE...
THE WINDS WILL BE EASTERLY AROUND 10 KNOTS TONIGHT INTO THIS
WEEKEND. THIS WILL KEEP THE ATLANTIC AND GULF WATER SEAS AROUND 2
FEET THROUGH THE WEEKEND. SO BOATING CONDITIONS SHOULD BE GOOD
THROUGH THIS WEEKEND OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS THAT
DO DEVELOP OVER SOUTH FLORIDA WATERS.
&&
.FIRE WEATHER...
THE RELATIVE HUMIDITY OVER SOUTH FLORIDA WILL REMAIN ABOVE THE 35
PERCENT CRITICAL VALUE THROUGH THIS WEEKEND. DEEP MOISTURE WILL
RETURN TO THE REGION EARLY TO THE MIDDLE PART OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 85 75 85 / 20 30 20 20
FORT LAUDERDALE 76 86 77 86 / 20 20 20 20
MIAMI 75 87 76 86 / 20 20 20 20
NAPLES 71 88 71 89 / 10 20 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...59/RM
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
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...
00Z UPDATE...
/ISSUED 756 PM EDT SAT MAY 18 2013/
ISOLATED SHOWERS ACROSS NORTH AND CENTRAL GEORGIA THIS
EVENING...BUT NOT ENOUGH TO MENTION IN THE TAFS FOR THE MOST PART.
IN A LULL IN TERMS OF PRECIP...BUT EXPECT COVERAGE TO INCREASE BY
SUNRISE...WITH THE BETTER CHANCES OF TSRA IN THE AFTERNOON SUNDAY.
MODELS DIFFER GREATLY THOUGH IN PRECIP FORECAST FOR TOMORROW...SO
CONFIDENCE IS LOW. COULD SEE SOME BR DEVELOP BY
MORNING...PARTICULARLY AT CSG...MCN AND AHN. MOSTLY MVFR CIGS THIS
EVENING...BUT WILL DETERIORATE TO IFR BY MORNING. CANNOT RULE OUT
SOME LIFR CIGS.
//ATL CONFIDENCE...00Z UPDATE...
HIGH CONFIDENCE ON WINDS. LOW CONFIDENCE ON CIGS...VSBYS AND
TIMING OF SHRA/TSRA.
11
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 63 77 65 84 / 50 60 60 40
ATLANTA 65 81 66 86 / 50 60 30 20
BLAIRSVILLE 62 76 60 82 / 60 70 70 40
CARTERSVILLE 64 81 65 88 / 60 60 30 20
COLUMBUS 67 86 67 89 / 30 40 30 10
GAINESVILLE 63 77 63 84 / 60 70 70 40
MACON 64 83 66 87 / 30 60 30 30
ROME 66 82 65 89 / 60 60 30 10
PEACHTREE CITY 64 82 65 87 / 50 60 30 20
VIDALIA 68 86 68 84 / 30 60 50 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...11
LONG TERM....DEESE
AVIATION...11
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1000 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL APPROACH FROM THE WEST THROUGH SUNDAY
BRINGING AN INCREASE IN MOISTURE AS WELL AS CHANCES OF SHOWERS AND
THUNDERSTORMS. THIS TROUGH WILL LINGER ACROSS THE EASTERN US WITH
UNSETTLED WEATHER THROUGH MUCH OF THE COMING WORK WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
ANOTHER WEAK SHORT WAVE IN NORTHEAST GEORGIA TRIGGERING SHOWERS IN
THE CSRA. ANOTHER SHORT WAVE FURTHER UPSTREAM IN TENNESSEE. INSTABILITY
AND LOW LEVEL CONVERGENCE HAVE WEAKENED ACROSS THE AREA BUT MODELS
INDICATE CONTINUED LIFT OVERNIGHT AND MOIST AIR MASS. WILL KEEP
CHANCE SHOWERS OVERNIGHT WITH ISOLATED THUNDERSTORMS. TEMPERATURES
TONIGHT FALLING INTO THE MID 60S.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
SOMEWHAT UNSETTLED WEATHER PATTERN THE NEXT SEVERAL DAYS. SURFACE
FRONT WILL REMAIN OFF TO THE NORTH OF THE AREA THROUGH THE PERIOD.
ALOFT...THE MAIN UPPER TROUGH WILL STILL BE JUST OFF TO THE WEST
OF THE REGION SUNDAY MORNING...THEN IT IS PROGGED TO VERY SLOWLY
TRACK EASTWARD INTO TUESDAY. RIDGING BEHIND THE TROUGH MAY BE ABLE
TO TAKE HOLD ENOUGH BY TUESDAY TO BRING LOWER RAIN CHANCES. UNTIL
THAT TIME...EXPECTING HIGH CHANCE TO LIKELY POPS THROUGHOUT THE
SHORT TERM PERIOD. RAIN AND THUNDERSTORM CHANCES WILL PROBABLY
COME IN WAVES...BUT DID NOT TRY TO PIN DOWN EXACT TIMING THIS FAR
OUT. NOT EXPECTING ANYTHING SEVERE WITH THE STORMS...JUST
OCCASIONAL LIGHTNING AND SOME HEAVIER RAINFALL. TEMPERATURES
SUNDAY AND MONDAY WILL BE DE PENDANT UPON CLOUD COVER AND RAINFALL.
FOR NOW IT APPEARS AS IF MOST AREAS SHOULD BE ABLE TO AT LEAST
CLIMB INTO THE LOWER 80S...BUT WOULD NOT BE SURPRISED IF SOME
AREAS THAT ARE IN THE HEAVIER RAINFALL REGIONS REMAIN IN THE 70S
THROUGH THE DAYTIME HOURS BOTH SUNDAY AND MONDAY. TUESDAY SHOULD
SEE A LITTLE MORE SUNSHINE...SO HIGHS EXPECTED TO BE ABLE TO CLIMB
INTO THE MID AND UPPER 80S ONCE AGAIN. AS FOR OVERNIGHT
LOWS...READINGS MAINLY IN THE 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
MOVING INTO THE LONG TERM...THE REGION WILL BE UNDER THE INFLUENCE
OF AN UPPER RIDGE BRIEFLY ON WEDNESDAY...THEN THE RIDGE SLIDES
OFFSHORE AS A DEEPENING TROUGH TAKES HOLE ACROSS THE MISSISSIPPI
VALLEY REGION OF THE COUNTRY. RAIN CHANCES LOW ON WEDNESDAY...THEN
INCREASE SLIGHTLY INTO SATURDAY AS THE MAIN UPPER TROUGH MOVES
EASTWARD TOWARDS THE FORECAST AREA. EXPECT MAINLY DIURNAL
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD THOUGH. EXPECT
TEMPERATURES CLOSE TO OR JUST ABOVE CLIMATOLOGY THROUGH THE
PERIOD.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
SHOWERS ASSOCIATED WITH A WEAK SHORTWAVE CONTINUE ACROSS THE AREA
LATE THIS EVENING AND COULD IMPACT TERMINALS WITH MVFR/IFR VSBYS IF
MOVING DIRECTLY OVERHEAD. WILL CONTINUE PREVAILING VFR AND HANDLE
WITH AMENDMENTS. CONVECTION SHOULD DIMINISH OVERNIGHT WITH LOSS OF
DIURNAL HEATING AND PASSING SHORTWAVE.
ALL GUIDANCE EXCEPT THE HRRR SUGGESTING IFR CEILINGS WILL DEVELOP
DURING THE PREDAWN HOURS SUNDAY. AM A LITTLE SKEPTICAL THAT IFR
CONDITIONS WILL DEVELOP BUT GIVEN MANY OF THE TERMINALS RECEIVED
RAINFALL TODAY AND THE OVERWHELMING AGREEMENT AMONG GUIDANCE WITH
SUPPORT FROM SREF WHICH ALSO SHOWS IFR CEILINGS...THEREFORE
INCLUDED A PERIOD OF IFR CEILINGS EARLY SUNDAY MORNING. LOW CLOUDS
SHOULD LIFT MID MORNING WITH VFR CONDITIONS RETURNING BY 16Z. WINDS
WILL GENERALLY BE FROM THE SOUTH LESS THAN 10 MPH.
UPPER SHORTWAVE WILL APPROACH FROM THE WEST AND SCATTERED
CONVECTION IS ONCE AGAIN EXPECTED ACROSS THE AREA. TIMING AND
LOCATION NOT CERTAIN ENOUGH TO INCLUDE IN THIS FORECAST.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND
THUNDERSTORMS...MAINLY AFTERNOON AND EVENING...POSSIBLE THROUGH
WEDNESDAY. DEPENDING ON CLOUD COVER AND RAINFALL...LATE NIGHT/EARLY
MORNING FOG/STRATUS MAY BE POSSIBLE AS WELL.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
812 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL APPROACH FROM THE WEST THROUGH SUNDAY
BRINGING AN INCREASE IN MOISTURE AS WELL AS CHANCES OF SHOWERS AND
THUNDERSTORMS. THIS TROUGH WILL LINGER ACROSS THE EASTERN US WITH
UNSETTLED WEATHER THROUGH MUCH OF THE COMING WORK WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SHOWERS AND THUNDERSTORMS CONTINUE ACROSS THE EASTERN MIDLANDS AND
PEE DEE BUT RADAR TRENDS SUGGEST DECREASING TREND. DECREASED POPS
ACROSS THE CENTRAL AND WESTERN MIDLANDS SIGNIFICANTLY WILL
SUBSIDENCE OCCURRING IN THE WAKE OF MID LEVEL SHORT WAVE TROUGH.
MODELS SUGGEST SHOWER AND THUNDERSTORM DEVELOPMENT THIS EVENING
ACROSS THE WESTERN MIDLANDS/CSRA HOWEVER THIS APPEARS OVERDONE.
LOWERED POPS FOR THE EVENING AND OVERNIGHT PERIOD...CONVECTION
LIKELY DIURNALLY DRIVEN AND MOS POPS OVERDONE. TEMPERATURES TONIGHT
FALLING INTO THE MID 60S.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
SOMEWHAT UNSETTLED WEATHER PATTERN THE NEXT SEVERAL DAYS. SURFACE
FRONT WILL REMAIN OFF TO THE NORTH OF THE AREA THROUGH THE PERIOD.
ALOFT...THE MAIN UPPER TROUGH WILL STILL BE JUST OFF TO THE WEST
OF THE REGION SUNDAY MORNING...THEN IT IS PROGGED TO VERY SLOWLY
TRACK EASTWARD INTO TUESDAY. RIDGING BEHIND THE TROUGH MAY BE ABLE
TO TAKE HOLD ENOUGH BY TUESDAY TO BRING LOWER RAIN CHANCES. UNTIL
THAT TIME...EXPECTING HIGH CHANCE TO LIKELY POPS THROUGHOUT THE
SHORT TERM PERIOD. RAIN AND THUNDERSTORM CHANCES WILL PROBABLY
COME IN WAVES...BUT DID NOT TRY TO PIN DOWN EXACT TIMING THIS FAR
OUT. NOT EXPECTING ANYTHING SEVERE WITH THE STORMS...JUST
OCCASIONAL LIGHTNING AND SOME HEAVIER RAINFALL. TEMPERATURES
SUNDAY AND MONDAY WILL BE DE PENDANT UPON CLOUD COVER AND RAINFALL.
FOR NOW IT APPEARS AS IF MOST AREAS SHOULD BE ABLE TO AT LEAST
CLIMB INTO THE LOWER 80S...BUT WOULD NOT BE SURPRISED IF SOME
AREAS THAT ARE IN THE HEAVIER RAINFALL REGIONS REMAIN IN THE 70S
THROUGH THE DAYTIME HOURS BOTH SUNDAY AND MONDAY. TUESDAY SHOULD
SEE A LITTLE MORE SUNSHINE...SO HIGHS EXPECTED TO BE ABLE TO CLIMB
INTO THE MID AND UPPER 80S ONCE AGAIN. AS FOR OVERNIGHT
LOWS...READINGS MAINLY IN THE 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
MOVING INTO THE LONG TERM...THE REGION WILL BE UNDER THE INFLUENCE
OF AN UPPER RIDGE BRIEFLY ON WEDNESDAY...THEN THE RIDGE SLIDES
OFFSHORE AS A DEEPENING TROUGH TAKES HOLE ACROSS THE MISSISSIPPI
VALLEY REGION OF THE COUNTRY. RAIN CHANCES LOW ON WEDNESDAY...THEN
INCREASE SLIGHTLY INTO SATURDAY AS THE MAIN UPPER TROUGH MOVES
EASTWARD TOWARDS THE FORECAST AREA. EXPECT MAINLY DIURNAL
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD THOUGH. EXPECT
TEMPERATURES CLOSE TO OR JUST ABOVE CLIMATOLOGY THROUGH THE
PERIOD.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS CONTINUE THIS EVENING
AROUND THE TERMINALS AND WILL INCLUDE VICINITY SHOWERS 00Z-02Z.
CONVECTION SHOULD DIMINISH DURING THE LATE EVENING HOURS WITH LOSS
OF DIURNAL HEATING WITH VFR CONDITIONS PREVAILING INTO THE
OVERNIGHT HOURS. ALL GUIDANCE EXCEPT THE HRRR SUGGESTING IFR
CEILINGS WILL DEVELOP DURING THE PREDAWN HOURS SUNDAY. AM A LITTLE
SKEPTICAL THAT IFR CONDITIONS WILL DEVELOP BUT GIVEN MANY OF THE
TERMINALS RECEIVED RAINFALL TODAY AND THE OVERWHELMING AGREEMENT
AMONG GUIDANCE WITH SUPPORT FROM SREF WHICH ALSO SHOWS IFR
CEILINGS...RELUCTANTLY INCLUDED A PERIOD OF IFR CEILINGS EARLY
SUNDAY MORNING. LOW CLOUDS SHOULD LIFT MID MORNING WITH VFR
CONDITIONS RETURNING BY 16Z. WINDS WILL GENERALLY BE FROM THE
SOUTH LESS THAN 10 MPH.
UPPER SHORTWAVE WILL APPROACH FROM THE WEST AND SCATTERED
CONVECTION IS ONCE AGAIN EXPECTED ACROSS THE AREA. TIMING AND
LOCATION NOT CERTAIN ENOUGH TO INCLUDE IN THIS FORECAST.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND
THUNDERSTORMS...MAINLY AFTERNOON AND EVENING...POSSIBLE THROUGH
WEDNESDAY. DEPENDING ON CLOUD COVER AND RAINFALL...LATE
NIGHT/EARLY MORNING FOG/STRATUS MAY BE POSSIBLE AS WELL.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1257 AM CDT FRI MAY 17 2013
.DISCUSSION...
930 PM CDT
THE FORECAST FOR TONIGHT HAS BEEN TWEAKED SLIGHTLY...TO CONTINUE
THE EVENING CHANCE OF THUNDER ACROSS THE SOUTHERN FORECAST AREA
THROUGH THE NIGHT...AND TO NUDGE IT NORTH SOME.
THE EVE WATER VAPOR LOOP DEPICTS THE CLOSED UPPER LOW ACROSS
NORTHERN AR EASING ITS WAY NORTHEAST. AT THE SURFACE...THE
PRIMARILY SYNOPTIC FRONT IS NEAR THE LOT/ILX CWA BORDER WITH A
LAKE BREEZE HAVING PUSHED WELL INLAND. BETWEEN THESE TWO A FEW
STORMS GENERATED...IT LOOKED LIKE ON A SLIGHTLY ELEVATED BOUNDARY
JUST NORTH OF THE SURFACE BOUNDARY PER ILX RADAR. THESE MAY FESTER
NORTHEAST ON THE AFOREMENTIONED MULTIPLE AREAS OF LOW-LEVEL
CONVERGENCE FOR SEVERAL MORE HOURS...BUT ANY CG LIGHTNING HAS BEEN
SPORADIC AT BEST AND WOULD EXPECT THAT TREND TO CONTINUE OR
DIMINISH ALTOGETHER. THE HRRR DOES INDICATE THESE SHOWERS TO SORT
OF OSCILLATE ALL THE WAY UP TO FAR NORTHEAST IL THROUGH EARLY
OVERNIGHT.
THE ILX VAD PROFILER INDICATES INCREASING SOUTHERLY FLOW BELOW 3K
FT...NOW UP TO 30 KT. THE LOW-LEVEL JET IS NOT EXPECTED TO
INCREASE MUCH FROM THAT MAGNITUDE AND POINT MORE INTO WESTERN IL.
MOISTURE TRANSPORT IS MORE LIMITED TONIGHT SO NOT EXPECTING AS
MUCH IF ANY ELEVATED CONVECTION...BUT COULD SEE SOME IN WESTERN IL
WHERE A LITTLE MORE THETA-E ADVECTION AND CONVERGENCE AROUND 850MB
IS FORECAST.
THE LAKE BREEZE MADE IMPRESSIVE PROGRESS WSW THROUGH EARLY EVE
AFTER SORT OF A SLOW START. A 30 DEGREE SPREAD AS OF 930 PM EXISTS
ACROSS THE CWA SIMPLY FROM JUST THIS MESOSCALE BOUNDARY. HAVE
ADJUSTED THE HOURLY TEMPERATURE FORECAST TO MEET TRENDS. THE LAV
GUIDANCE HAS VERY LITTLE TEMPERATURE DROP FOR MANY POINTS THROUGH
THE REST OF THE NIGHT...LIKELY DUE TO INCREASING CLOUD COVER.
WHILE CAA OFF THE LAKE LIKELY WILL CREATE A LITTLE MORE DROP THAN
IT ADVERTISES...THIS IS IN LINE WITH THE GOING MINIMUM TEMPERATURE
FORECASTS.
MTF
//PREV DISCUSSION...
259 PM CDT
TODAY`S FORECAST CHALLENGES CONTINUE TO BE DEALING WITH FRONTAL
BOUNDARY CURRENTLY JUST SOUTH OF THE CWA...AND PERIODIC CONVECTIVE
CHANCES THROUGH MID NEXT WEEK.
TODAY AND TONIGHT...
THIS AFTERNOON THE FRONT IS LOCATED JUST NORTH OF QUINCY IL EAST TO
NEAR TERRE HAUTE INDIANA...AND HAS BEEN SLOWLY PUSHING NORTH THIS
AFTERNOON. MODERATE INSTABILITY EXISTS SOUTH OF THE FRONT AND MAY
LIFT INTO FAR SOUTHERN PORTIONS OF THE CWA LATE THIS EVENING BEFORE
FADING NOCTURNALLY. MAINTAINED SLT CHC POPS FOR A FEW HOURS THIS
EVENING WHEN THIS OCCURS...BUT OTHERWISE SHOULD BE FAIRLY QUIET
PERIOD THROUGH TONIGHT.
FRIDAY THROUGH SATURDAY...
COMPACT SHORTWAVE NOTED ON WV IMAGERY THIS AFTERNOON OVER WESTERN
NE/KS WILL CONTINUE ENE INTO WEST CENTRAL WISCONSIN BY FRIDAY
AFTERNOON. AS THIS HAPPENS...SOUTHERLY FLOW INCREASE AT THE SURFACE
AND SHOULD HELP PUSH THE BOUNDARY NORTH ACROSS THE AREA. DEWPOINTS
RISE INTO THE MID 60S AND MODEST INSTABILITY DEVELOPS OUTSIDE OF FAR
NE ILLINOIS WHERE ONSHORE WINDS WILL KEEP CONDITIONS COOLER/MORE
STABLE. THIS INSTABILITY IS UNCAPPED...AND GIVEN THERE IS NO WELL
DEFINED FOCUS FOR THUNDERSTORMS...EXPECT UNORGANIZED/SCATTERED
CONVECTION TO DEVELOP WITHIN THE WARM SECTOR. MID LEVEL LAPSE RATES
ARE PRETTY POOR...SO CONVECTION MAY STRUGGLE AT TIMES AND MAY LIMIT
THE THUNDER CHANCES TO SOME DEGREE. MUCH OF THE SAME IS EXPECTED
SATURDAY SO WILL MAINTAIN THE LOW POPS FOR DIURNALLY DRIVEN TSTORMS.
SUNDAY THROUGH TUESDAY...
THIS PERIOD CONTINUES TO LOOK ACTIVE AS THE OVERALL PATTERN
AMPLIFIES WITH DEEP TROUGHING DEVELOPING ACROSS THE WESTERN
CONUS...AND STRONG RIDGING EAST. THE H85 THERMAL RIDGE BEGINS TO
WORK INTO THE AREA SUNDAY...AS WELL AS DRY AIR ALOFT AND THE EML
LATER IN THE DAY HELPING TO STEEPEN LAPSE RATES ALOFT. NEGATIVELY
TILTED TROUGH IS EXPECTED TO ROUND THE BASE OF THE LONGWAVE TROUGH
SUNDAY LIFTING INTO THE MID MISSOURI VALLEY SUNDAY NIGHT. MODELS ARE
MIXED ON WHETHER OR NOT THE CIN ERODES DURING THE DAYTIME...BUT IF
IT DOES CHANCES WILL BE BEST OVER WESTERN PORTIONS OF THE CWA...SO
HAVE MAINTAINED LOWER POPS. THERE MAY BE A BETTER CHANCE FOR
CONVECTION OVERNIGHT AS A LOW LEVEL JET DEVELOPS JUST TO OUR WEST
WITH LARGE SCALE ASCENT ASSOCIATED WITH AFOREMENTIONED TROUGH.
ON MONDAY...THE GFS INDICATES ANOTHER LOWER AMPLITUDE DISTURBANCE
WILL ROUND THE BASE OF THE LONGWAVE TROUGH AND LIFT INTO THE MID
MISSISSIPPI VALLEY. THIS CONTINUES TO BE A DAY TO KEEP AN EYE ON FOR
SEVERE WEATHER POTENTIAL. MODELS CONTINUE TO ADVERTISE MODERATE TO
STRONG INSTABILITY IN PLACE OVERHEAD WITH MARGINAL SHEAR CONDITIONS
TO SUPPORT SEVERE WEATHER. AS PREVIOUSLY MENTIONED...CONVECTION FROM
THE PREVIOUS NIGHT...CLOUD COVER...AND OTHER SMALL SCALE FEATURES
CANNOT BE RESOLVED THIS FAR OUT AND ADD A CONSIDERABLE AMOUNT OF
UNCERTAINTY. WE SHOULD BEGIN TO GET A BETTER PICTURE THIS WEEKEND SO
STAY TUNED FOR FORECAST UPDATES. DEPENDING ON THE SPEED OF THE
SYSTEM...TUESDAY WILL ALSO HAVE TO BE MONITORED...PERHAPS WITH THE
THREAT MORE FOCUSED ON THE EASTERN PORTIONS OF THE CWA.
IN ADDITION TO THE SEVERE THREAT...MULTIPLE ROUNDS OF THUNDERSTORMS
MOVING ALONG THE SLOW MOVING BOUNDARY SUNDAY NIGHT THROUGH TUESDAY
WILL LEAD TO A INCREASED HEAVY RAIN AND FLOODING THREAT.
FOR TEMPERATURES SUNDAY AND MONDAY...CONTINUE TO LEAN ON THE WARMER
BIAS CORRECTED GEM WHICH HAPPENED TO VERIFY BEST WITH THE
UNSEASONABLY HEAT TUESDAY. DEPENDING ON THE SPEED OF THE
SYSTEM...CURRENT FORECAST TEMPS MAY BE A BIT ON THE COOL SIDE
TUESDAY...PARTICULARLY THE EASTERN CWA. H85 TEMPS OF 16-18C AND H92
TEMPS OF 19-22C SHOULD SUPPORT TEMPERATURES WELL INTO THE 80S AND
WOULDN`T BE SURPRISED TO SEE PLACES HIT 90S THOSE DAYS...BUT WILL
REMAIN A BIT CONSERVATIVE GIVEN THE PRECIP CHANCES AND CLOUD COVER.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* ISOLATED SHOWER REMAIN SOUTHWEST OF TERMINALS THRU MID-MORNING.
* PRECIP COVERAGE INCREASES BY MIDDAY...POSSIBLE THUNDERSTORM ARND
19-22Z.
* WINDS REMAIN EASTERLY WITH SPEEDS GENERALLY ARND 10KT OR
LESS...TURNING SOUTHEASTERLY AFT 05Z SAT.
* CIGS REMAIN VFR...POSSIBLE MVFR CIGS IN OR AROUND TSRA/SHRA.
BEACHLER
//DISCUSSION...UPDATED 06Z...
IR IMAGERY EARLY THIS MORNING SHOWS AN AREA OF CLOUDS ACROSS THE
WESTERN GREAT LAKES INTO THE UPPER MIDWEST. SCT SHOWERS/THUNDERSTORMS
ACROSS NORTHCENTRAL IOWA/SOUTHCENTRAL MINNESOTA. THIS PRECIPITATION WAS LOCATED
ALONG A STALLED FRONTAL BOUNDARY THAT STRETCHES EAST/SOUTHEAST
INTO CENTRAL IL/IN. AIRFIELDS ACROSS NORTHERN IL/NORTHWEST IN
REMAIN VFR...WITH SOME CLOUDS OBSERVED AT 8KFT AGL OR HIGHER.
GUIDANCE CONTINUE TO SUGGEST VFR CONDS WILL CONTINUE THROUGH
DAYBREAK...WITH A CONTINUED LIGHT EAST WIND ARND 8KT OR LESS. THE
DIRECTION WILL GENERALLY REMAIN BETWEEN A 060-090 DEG
RANGE...HOWEVER SOME VRB DIRECTIONS MAY OCCUR THRU DAYBREAK AS
SPEEDS WILL BE LESS THAN 5 KT.
THEN IT APPEARS THE BEST CHC FOR PRECIP WILL OCCUR SOUTHWEST OF
THE TAF SITES THRU MUCH OF THE MORNING...WITH MINIMAL COVERAGE. BY
MIDDAY COVERAGE SHUD BEGIN TO INCREASE IN
SHOWERS/THUNDERSTORMS...AND GUIDANCE IS BEGINNING TO SHOW A HIGHER
CONFIDENCE IN TIMING OF 18-22Z. HAVE OPTED TO PLACE A VCSH TO
HANDLE THE BEGINNING COVERAGE AT 16Z...WITH A TEMPO IN A 19-22Z
TIMEFRAME. THIS APPEARS TO BE THE BEST TIME THAT A THUNDERSTORM
WOULD OCCUR. THEN IT APPEARS ANY PRECIP WILL PUSH BACK TO THE
WEST/SOUTHWEST OF THE AIRFIELDS...WITH A SMALL CHC OF PRECIP
CONTINUEING THROUGH THE EVENING HOURS. WINDS WILL EVENTUALLY BEGIN
TO TURN SOUTHEASTERLY ONCE THE BOUNDARY LIFTS OVERHEAD AND TO THE
NORTH OF THE TAF SITES...HOWEVER THIS DOES NOT APPEAR TO OCCUR
UNTIL AFT 05Z SAT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* MEDIUM CONFIDENCE IN CIGS FORECAST.
* LOW CONFIDENCE IN PRECIP TIMING/COVERAGE.
* MEDIUM CONFIDENCE IN THUNDERSTORMS.
* MEDIUM/HIGH CONFIDENCE IN WIND DIRECTION BECOMING SOUTHEAST
TIMING.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY THROUGH WEDNESDAY...PERIODIC CHANCES FOR SHRA/TSRA...
OTHERWISE...VFR.
KREIN
&&
.MARINE...
228 PM CDT
RIDGING FROM HIGH PRESSURE CENTERED OVER WESTERN ONTARIO EXTENDS
ACROSS LAKE MICHIGAN THIS AFTERNOON. WEAK LOW PRESSURE WILL DEVELOP
AND MOVE UP THE OHIO RIVER VALLEY FRIDAY WITH ADDITIONAL LOW
PRESSURE DEVELOPING ACROSS THE CENTRAL HIGH PLAINS. EAST TO
NORTHEAST FLOW OVERALL WILL CONTINUE ACROSS THE LAKE...WITH ONSHORE
FLOW IN AREAS WHERE THE PRESSURE GRADIENT IS WEAKER CAUSING SOME
ERRATIC DIRECTIONS AT TIMES. STEADIER AND MORE UNIFORM WINDS WILL
DEVELOP WITH TIME THROUGH TOMORROW WITH MORE OF AN EAST TO SOUTHEAST
TREND. THE STRONGEST WINDS WILL OCCUR FRIDAY EVENING/NIGHT
COINCIDENT WITH THE STRONGEST PRESSURE GRADIENT THANKS TO THE LOW
PASSING TO THE SOUTHEAST. THE GRADIENT WEAKENS DURING THE DAY
SATURDAY AS THE LOW DEPARTS TO THE EAST. LOW PRESSURE STRENGTHENS
ACROSS THE CENTRAL/NORTHERN HIGH PLAINS INTO SUNDAY WHICH WILL
GRADUALLY TIGHTEN THE PRESSURE GRADIENT ACROSS THE LAKE. THIS WILL
ALLOW A STEADY SOUTH TO SOUTHEAST WIND TO DEVELOP ACROSS MOST OF THE
LAKE...WITH A MORE EASTERLY DIRECTION ACROSS THE FAR NORTH WHERE A
WARM FRONTAL BOUNDARY IS EXPECTED TO SET UP. THE MAIN LOW WILL
MEANDER NORTHWARD BEFORE BEING PUSHED EASTWARD ACROSS MINNESOTA/IOWA
SOMETIME TUESDAY OR WEDNESDAY WHICH WILL LIKELY PUSH THE FRONTAL
BOUNDARY FURTHER SOUTH ACROSS THE LAKE LEADING TO EAST TO NORTHEAST
WINDS NORTH AND SOUTH TO SOUTHWEST WINDS SOUTH BY MID WEEK. THE MAIN
CONCERN WILL BE THE POTENTIAL FOR INCREASED GUSTINESS ACROSS THE
NORTH AS COLDER AIR SETTLES IN ALLOWING SLIGHTLY INCREASED MIXING.
OTHERWISE...GENERALLY STABLE LOW LEVEL AIR ACROSS THE LAKE WILL KEEP
GUSTS TO A MINIMUM FROM TONIGHT THROUGH THE WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1154 PM CDT THU MAY 16 2013
.DISCUSSION...
ISSUED 743 PM CDT THU MAY 16 2013
SYNOPTIC FRONTAL BOUNDARY HAS LIFTED NORTHWARD TO NEAR THE I-74
CORRIDOR EARLY THIS EVENING. DEWPOINTS TO THE SOUTH OF THE
BOUNDARY ARE IN THE UPPER 50S AND LOWER 60S ACROSS MUCH OF THE
KILX CWA...WHILE DEWPOINTS NORTH OF THE FRONT ARE ONLY IN THE 40S
ACROSS NORTHERN ILLINOIS. MESOSCALE OUTFLOW BOUNDARY FROM CONVECTION
EARLIER TODAY FROM NEAR SPRINGFIELD S/SE TO LAWRENCEVILLE HAS
LIFTED NORTHWARD AS WELL...RESULTING IN A RELATIVELY STABLE
AIRMASS ACROSS THE AREA. BEST INSTABILITY AND LIFT IS CURRENTLY
FOCUSED ALONG/NORTH OF THE FRONTAL BOUNDARY ACROSS THE FAR
NORTHERN CWA. A FEW SHOWERS HAVE DEVELOPED ACROSS WOODFORD AND
NORTHERN MCLEAN COUNTIES OVER THE PAST HOUR...AND THIS AREA WILL
HAVE TO BE MONITORED FOR ADDITIONAL DEVELOPMENT AS THE EVENING
PROGRESSES. WILL MAINTAIN SLIGHT CHANCE POPS EVERYWHERE DURING THE
EVENING...THEN WILL LIMIT POPS TO ONLY THE NORTHERN CWA IN CLOSER
PROXIMITY TO THE FRONT OVERNIGHT. ZONE UPDATE HAS ALREADY BEEN
SENT.
&&
.AVIATION...
ISSUED 1154 PM CDT THU MAY 16 2013
04Z/11PM RADAR IMAGERY SHOWS DRY CONDITIONS ACROSS MUCH OF CENTRAL
ILLINOIS...WITH ONE CLUSTER OF PERSISTENT SHOWERS/THUNDER BETWEEN
KVYS AND KPNT. STATIONARY FRONTAL BOUNDARY JUST NORTH OF THE I-74
CORRIDOR WILL CONTINUE TO TRIGGER ISOLATED CONVECTION
OVERNIGHT...HOWEVER IT IS EXPECTED TO REMAIN NORTH OF THE KILX
TERMINALS. UPPER LOW CURRENTLY SPINNING OVER THE OZARKS WILL LIFT
NORTHEASTWARD INTO THE OHIO RIVER VALLEY ON FRIDAY. DEEPER
MOISTURE ARRIVING WITH THIS FEATURE WILL LEAD TO SCATTERED SHOWERS
AND THUNDERSTORMS THROUGHOUT THE DAY INTO THE EARLY EVENING. BASED
ON NAM TIMING...HAVE INTRODUCED VCTS AT KSPI AND KDEC BY
13Z...THEN FURTHER NORTH TO KPIA BY 16Z. AS LOW SHIFTS FURTHER
EAST AND DAYTIME INSTABILITY IS LOST...CONVECTION WILL DISSIPATE
AFTER 02Z. WINDS WILL BE LIGHT AND SOUTHERLY OVERNIGHT...THEN WILL
BACK TO E/SE ON FRIDAY.
BARNES
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT THU MAY 16 2013
A STATIONARY FRONT WILL OSCILLATE NORTH AND SOUTH ACROSS ILLINOIS
OVER THE NEXT DAY AND A HALF...THEN THE FRONT SHOULD LIFT NORTH AS
A WARM FRONT FOR THE WEEKEND...PUSHING HIGHS INTO THE MID TO UPPER
80S BY SUNDAY. BANDS OF THUNDERSTORMS THAT DEVELOP THROUGH
TOMORROW WILL LIKELY BE SLOW MOVING, HEAVY RAIN PRODUCERS LIKE
TODAY`S STORMS. LOCALIZED AREAS COULD SEE SIGNIFICANT RAINFALL OF
2-3 INCHES IN A COUPLE HOURS WHILE NEARBY AREAS SEE LITTLE RAIN.
PINPOINTING THAT ACTIVITY WILL BE DIFFICULT...BUT DIURNAL TRENDS
SHOULD PUT MOST OF THE CONVECTION DURING THE AFTERNOON
TOMORROW...ESPECIALLY NEAR ANY OUTFLOW BOUNDARIES SET DOWN BY
TODAY`S STORMS.
A SLIGHT LULL IN STORMS SHOULD OCCUR THIS WEEKEND AS RIDGING IN
THE PLAINS BUILDS INTO IL. A STRONGER COLD FRONT IS EXPECTED TO
PUSH ACROSS IL ON MONDAY AND MONDAY NIGHT...BRINGING OUR BETTER
CHANCES OF THUNDERSTORMS. WE ARE IN THE SPC DAY 5 OUTLOOK FOR
STRONG TO SEVERE STORMS MON-MON NIGHT. A COOL DOWN IS PROJECTED
FOR TUES THROUGH THURSDAY BEHIND THE COLD FRONT...PULLING HIGHS
BACK INTO THE 70S...BUT STILL AT OR ABOVE NORMAL.
SHORT TERM...TONIGHT THROUGH SUNDAY.
SHOWERS AND STORMS WILL GENERALLY BE DIMINISHING AS WE HEAD INTO
THE EVENING. THE LINE OF CONVECTION MAINLY CENTERED ON A LINE
FROM RUSHVILLE TO TAYLORVILLE TO EFFINGHAM TO LAWRENCEVILLE...IS
EXPECTED TO LIFT NORTH THIS EVENING. THE RAP MODEL IS SHOWING THE
INSTABILITY AXIS FOLLOWING THE SAME PROGRESSION...WITH SOME SHOWER
ACTIVITY DEVELOPING DURING THAT TIME. IN THE LAST HOUR...PRECIP
COVERAGE AND UPDRAFT INTENSITY HAVE ALREADY BEGUN DIMINISHING OR
WEAKENING RESPECTIVELY. RADAR LOOPS SHOW VARIOUS OUTFLOW
BOUNDARIES MOVING NORTH ACROSS OUR COUNTIES...AND MAY END UP BEING
A FOCUS FOR EVENING SHOWERS ALONG AND NORTH OF I-72.
STILL...COVERAGE WILL BE ISOLATED IN GENERAL.
FRIDAY MORNING...THE LOCATION OF THE BEST INSTABILITY WILL BE
ALONG AND NORTH OF I-74...SO ANY MORNING CONVECTION ON FRIDAY MAY
BE FOCUSED IN THAT AREA. DURING THE AFTERNOON...AN UPPER LOW
PRESSURE WAVE IS FORECAST TO LIFT NORTHEAST ACROSS IL...IN CONCERT
WITH INCREASING MOISTURE AND INSTABILITY AS THE STATIONARY FRONT
OSCILLATES NORTHWARD WITH THE WAVE. COVERAGE OF STORMS SHOULD BE
MORE THAN TODAY...BASED ON THE SUPPORT OF THE UPPER WAVE AND JET
DYNAMICS. ANY SUNSHINE THAT HEATS UP THE BOUNDARY LAYER WILL HELP
TO CREATE A FEW STRONG UPDRAFTS WITH SMALL HAIL, GUSTY WINDS, AND
VERY HEAVY RAINFALL.
THE STORMS MAY LINGER INTO THE EVENING EAST OF I-57...BUT SHOULD
DIMINISH BY MIDNIGHT. BY 12Z SAT MORNING...THE UPPER LOW IS
FORECAST TO BE CENTERED IN SOUTHERN INDIANA...WHICH WILL HELP PUT
PRECIP CHANCES MAINLY IN OUR SOUTHEAST COUNTIES ALONG AND SOUTHEAST
OF A LINE FROM SHELBYVILLE TO PARIS. THE SLOW DEPARTURE OF THE LOW
WILL KEEP CHANCES OF SHOWERS AND STORMS THROUGH SATURDAY AFTERNOON
IN THE SOUTHEAST.
THE WARM FRONT DEPARTING INTO NORTHERN IL FOLLOWED BY RIDGING AT
THE SURFACE AND ALOFT SATURDAY NIGHT AND SUNDAY SHOULD HELP MAKE
MOST AREAS DRY FOR THE LAST HALF OF THE WEEKEND. THE ADDITIONAL
SUNSHINE ON SUNDAY ALONG WITH DEEPER WARM AIR WILL HELP PUSH HIGH
TEMPS INTO THE MID TO UPPER 80S...WITH MUGGY DEWPOINTS IN THE
UPPER 60S TO NEAR 70. HEAT INDEX READINGS SUNDAY AFTERNOON WILL
CLIMB INTO THE 90S.
LONG TERM...MONDAY THROUGH THURSDAY.
ON MONDAY...AN OCCLUDING LOW PRESSURE PRESSURE SYSTEM IN THE
EASTERN DAKOTAS WILL CREATE SOME WARM FRONTOGENESIS TO THE
SOUTHEAST OF THE LOW ACROSS OUR NORTHERN COUNTIES. THAT WILL
CREATE A FOCUS FOR CONVECTION BY MONDAY AFTERNOON. MONDAY
NIGHT...A COLD FRONT WILL MOVE ACROSS IL PRODUCING STRONG TO
SEVERE STORMS AS ML-CAPE VALUES CLIMB TO NEAR 2K J/KG. BULK SHEAR
IS EXPECTED TO REACH OVER 40KT AS WELL...SO EMBEDDED SUPERCELLS
WILL BE POSSIBLE IN THE LINE OF STORMS THAT MOVES THROUGH.
STORMS ARE EXPECTED TO LINGER INTO TUESDAY AS THE UPPER COLD POOL
SLOWLY MAKES PROGRESS INTO ILLINOIS. WE KEPT LIKELY POPS SOUTHEAST
OF I-72...AND CHANCE ELSEWHERE. TUESDAY NIGHT PRECIP COVERAGE
SHOULD DIMINISH...WITH CHANCE POPS STILL IN PLACE ACROSS THE
BOARD. AN ELONGATED SURFACE TROUGH IS PROJECTED TO LINGER ACROSS
NORTHERN ILLINOIS INTO WED AS THE OCCLUDED UPPER LOW BECOMES MORE
OF AN OPEN WAVE AND SEND A SURFACE LOW EASTWARD ACROSS WISCONSIN.
THAT PROGRESSION WILL KEEP SCATTERED SHOWERS POSSIBLE AS FAR
SOUTH AS CENTRAL ILLINOIS THROUGH THURSDAY...ESPECIALLY EAST OF
I-55. PRECIP AMOUNTS MID WEEK SHOULD REMAIN LIGHT...BUT STILL
CLOUDS AND COOLER AIR WILL KEEP HIGH TEMPS BACK IN THE
70S...CLOSER TO NORMAL.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
224 AM EDT FRI MAY 17 2013
.SYNOPSIS...
ISSUED AT 205 AM EDT FRI MAY 17 2013
A STATIONARY FRONT WILL REMAIN OVER THE AREA WITH A CHANCE FOR
SHOWERS AND THUNDERSTORMS IN THE VICINITY OF THE FRONT AND SOUTH
OF THE FRONT. SHOWER AND THUNDERSTORM CHANCES WILL PERSIST
THROUGH THE WEEKEND AS THE FRONT REMAINS ACROSS THE AREA. ABOVE
NORMAL TEMPERATURES ARE EXPECTED THIS WEEKEND. CHANCES FOR SHOWERS
AND THUNDERSTORMS INCREASE EARLY NEXT WEEK AS A STORM SYSTEM
APPROACHES FROM THE WEST.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
HIGH PRESSURE HAS KEPT BULK OF MSTR JUST FAR ENOUGH SOUTH OF THE
AREA TODAY TO ALLOW FOR GENERALLY DRY CONDITIONS AND TEMPS MOVING
WELL THROUGH THE 70S IN MOST SPOTS. A FEW LIGHT SHOWERS/SPRINKLES
WERE NOTED ALONG FIRST OF 2 SFC THETA E GRADIENTS ACROSS FAR
SOUTHERN COUNTIES. THIS AREA IS EXPECTED TO SHIFT SOUTH OVER THE
NEXT SEVERAL HOURS AND REMOVE ANY CHANCE FOR PRECIP FOR THE
REMAINDER OF THE NIGHT. SECONDARY GRADIENT WAS LOCATED FURTHER
SOUTH ACROSS SOUTHERN INDIANA WHERE CONVECTION HAS BEEN ONGOING
MUCH OF THE DAY. MODELS TEND TO SUGGEST THAT THIS SECONDARY AREA
OF MSTR/GREATER LIFT SUPPORT WITH MAIN SFC BOUNDARY WILL BRING
INCREASING CHANCES FOR SHOWERS AND STORMS ON FRIDAY. IT WOULD
APPEAR THAT MOST FAVORABLE TIMING WOULD BE MID TO LATE AFTERNOON
FRIDAY IN FAR SW SECTIONS WITH PROGRESSION NE HAMPERED SOMEWHAT BY
DRY AIR/SEMI DRY GROUND CONDITIONS. IF NEW RUN OF SPC 4KM WRF IS
FOLLOWED...CONVECTION WOULD NOT ARRIVE UNTIL AFTER 00Z SAT. HAVE
ADJUSTED GRIDS TO REFLECT THIS WITH SLGT CHC TO CHC POPS CONFINED
TO AFTERNOON.
CLOUD COVER WILL BE ON THE INCREASE...WHICH WILL BUT A DAMPER ON
POTENTIAL CLIMB IN HIGHS. THAT BEING SAID...HIGHS SHOULD STILL END
UP ABOVE NORMAL CLIMBING INTO THE MID AND UPPER 70S.
&&
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
WATER VAPOR IMAGERY AND LATEST RAP ANALYSIS THAT IS DEPICTING MID
LEVEL CIRCULATION MOVING EASTWARD ACROSS THE SOUTHERN PLAINS THIS
AFTERNOON WILL HAVE AN IMPACT ON THE BEGINNING OF THE EXTENDED
FCST PERIOD AS IT MOVES ACROSS THE TN VALLEY. THIS WILL ACT ON
STATIONARY SFC BOUNDARY IN ADVECTING MOISTURE IN AN OVERRUNNING
FASHION BACK NORTH OF THE BOUNDARY AND LEND SUPPORT TO WIDELY
SCATTERED CONVECTION OVER THE SW HALF OF THE CWA. FOCUS WILL THEN
SHIFT TO AMPLIFICATION OF THE UPPER LEVEL PATTERN AS STRONG JET
DYNAMICS CURRENTLY WELL OUT IN THE PACIFIC ARE PROGGED BY MEDIUM
RANGE MODELS TO COME ONSHORE AND DEVELOP DEEP UPPER TROF OVER THE
WESTERN US. THIS WILL INDUCE DOWNSTREAM RIDGING THAT WILL BUILD
INTO THE REGION SUN/MON BRINGING WARMER AND MAINLY DRY CONDITIONS
TO THE AREA. WESTERN CONUS UPPER TROF THEN EXPECTED TO BECOME
VERTICALLY STACKED CLOSED SYSTEM IN THE NORTHERN PLAINS WHICH
MODELS ARE STRUGGLING WITH TIMING OF THE EVENTUAL EJECTION OF THIS
SYSTEM INTO OUR AREA. AS EXPECTED OVERALL TREND CONTINUES TO BE
SLOWER WITH ARRIVAL OF MAIN SYSTEM NOW DELAYED TO TUE/WED
TIMEFRAME AND BRINGING WITH IT THE BEST CHANCES FOR PRECIP. PRIOR
TO ITS ARRIVAL...BECOMING MORE AND MORE DIFFICULT TO PICK OUT
MODELS HANDLING OF INCREASINGLY DIFFUSE SFC BOUNDARY BUT
INDICATIONS ARE BOUNDARY WILL LIFT NORTH OF THE AREA IN
CONJUNCTION WITH UPPER RIDGE MOVING OVER THE AREA WHICH SHOULD
LEAVE MUCH OF THE FORECAST AREA IN A CAPPED WARM SECTOR SUN/MON.
LOW CONFIDENCE IN ANY ONE PARTICULAR SCENARIO WITH THIS SETUP BUT
WILL STILL INJECT A PERIOD OR TWO OF DRY WEATHER TO REFLECT THIS.
ANTICIPATE TEMPS WELL INTO THE 80S ON MONDAY DEPENDING ON AMOUNT
OF SUN...BUMPED ALLBLEND UP A DEGREE TO START UPWARD TREND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 205 AM EDT FRI MAY 17 2013
A WELL DEFINED FRONT WAS JUST SOUTHWEST OF THE TERMINALS EARLY
THIS MORNING. THE FRONT SHOULD BE NEARLY STATIONARY TODAY...BUT MAY
DRIFT NORTH AS A WARM FRONT LATER TODAY. ADDED A VICINITY SHOWER
AT BOTH TERMINALS LATE IN THE DAY WITH THE FRONT IN THE VICINITY
AND DURING MAXIMUM DAYTIME INSTABILITY. THERE IS ALSO AN OUTSIDE
CHANCE FOR THUNDER...MAINLY LATE AFTERNOON INTO EARLY
EVENING...BUT FOR NOW...LEFT THUNDER OUT GIVEN THE MORE ISOLATED
NATURE OF COVERAGE EXPECTED. KEPT TAFS VFR.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...BENTLEY
SHORT TERM...FISHER
LONG TERM...JAL
AVIATION...SKIPPER
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
646 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...19/00Z
ISSUED AT 646 PM CDT SAT MAY 18 2013
POTENT UPPER LEVEL FEATURE LIFTING THROUGH CENTRAL KS WILL CONTINUE
TO SHIFT TO THE NE THROUGH 12Z. THUNDERSTORMS ASSOCIATED WITH THIS
FEATURE MAY ENTER SW IA BY 08Z BUT WILL MORE LIKELY SHIFT INTO MO
WHILE A SECONDARY BAND OF STORMS DEVELOPS ALONG A WEAK BOUNDARY IN
ABOUT THE SAME LOCATION. THE STORMS WILL SHIFT NE THROUGH 12Z
ACROSS TAF LOCATIONS. SOME THREAT OF LARGE HAIL WITH THESE STORMS
BUT THE BIGGER CONCERN WILL BE HEAVY RAINFALL. FROM 12Z THROUGH
20/00Z MORNING CONVECTION WILL SHIFT OUT OF TAF LOCATIONS WITH A BIT
OF A BREAK IN THE EARLY AFTERNOON HOURS. AFTER 20Z WE WILL
DESTABILIZE AS ANOTHER UPPER LEVEL FEATURE APPROACHES.
STRONG/SEVERE STORMS POSSIBLE DURING THIS PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...FAB
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1230 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 649 AM CDT FRI MAY 17 2013
THE NOCTURNAL MCS WILL CONTINUE MOVING EAST FROM MN INTO WI THIS
MORNING BEFORE SLOWLY DISSIPATING. BOUNDARIES LEFT OVER FROM THAT
CONVECTION WILL BE THE PRIMARY FOCUS FOR DIURNAL CONVECTION TODAY.
MCS AND LIFT TOOLS PER RAP TRENDS SHOW THE THETA E GRADIENT AND
ASSOCIATED CONVERGENCE/LIFT IS JUST NORTH OF THE AREA. THUS DRY
CONDITIONS ARE EXPECTED THROUGH MID DAY ACROSS THE AREA. THE
CURRENT FCST HAS CONVECTION DEVELOPING IN THE AFTERNOON BUT IT IS
DEPENDENT ON WHEN CONVECTIVE TEMPERATURE IS ACHIEVED. IF THE RAP IS
CORRECT WE WOULD REMAIN BELOW CONVECTIVE TEMPERATURE. HOWEVER...
THE RAP TRENDS DO SHOW AREAS OF CONVERGENCE DEVELOPING DURING THE
AFTERNOON ALONG WITH WEAK THETA E GRADIENTS.
SO...ISOLATED TO SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON
WITH THE NORTH THIRD MORE FAVORED DUE TO THE PROXIMITY OF THE
FRONTAL BOUNDARY. STORMS WILL BE SLOW MOVING DUE TO THE UPPER
RIDGE SO ANY THUNDERSTORM THAT DEVELOPS WILL HAVE THE POTENTIAL TO
PRODUCE VERY LOCALIZED HEAVY RAINFALL OF AN INCH OR MORE. ..08..
&&
.SYNOPSIS...
ISSUED AT 229 AM CDT FRI MAY 17 2013
06Z SFC ANALYSIS HAS A WEAK LOW IN WESTERN IOWA JUST EAST OF KSUX
AND ANOTHER IN SOUTHERN SOUTH DAKOTA. AN EAST/WEST FRONTAL BOUNDARY
RAN FROM NORTHERN OHIO...THROUGH CENTRAL INDIANA...AND TO THE LOW
NEAR KSUX. FLOW OFF LAKE MICHIGAN HAD DEW POINTS RANGING FROM THE
UPPER 30S NORTH OF THE FRONT TO 50S AND LOW 60S SOUTH OF THE FRONT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 229 AM CDT FRI MAY 17 2013
THE CURRENT CONVECTION ON RADAR IS OCCURRING ALONG A THETA E
GRADIENT AND MOISTURE/TEMPERATURE GRADIENTS FROM THE 850MB FRONT.
MOST OF THE AREA WILL REMAIN DRY THROUGH SUNRISE EXCEPT FOR VERY
ISOLATED CONVECTION IN THE HWY 20 CORRIDOR.
THE MORNING HOURS ARE EXPECTED TO BE MAINLY DRY WITH PASSING CLOUDS
AS THE THETA E GRADIENT MOVES NORTH INTO WISCONSIN. DIFFERENTIAL
HEATING COMBINED WITH AN APPROACHING VORT MAX SHOULD RESULT IN
ISOLATED TO SCATTERED CONVECTION DEVELOPING BY LATE MORNING IN THE
EASTERN CWFA.
DURING THE AFTERNOON HOURS...ISOLATED TO SCATTERED CONVECTION WILL
EXPAND TO MOST OF THE CWFA AS CONVECTIVE TEMPERATURES ARE REACHED.
THE PROXIMITY OF THE UPPER RIDGE MEANS THAT STEERING CURRENTS FOR
THE CONVECTION ARE VERY WEAK. THUS THOSE AREAS THAT DO SEE RAIN THIS
AFTERNOON WILL HAVE THE POTENTIAL TO SEE LOCALLY HEAVY RAINFALL.
CONVECTION WILL SLOWLY DIMINISH WITH SUNSET BUT ISOLATED TO
SCATTERED CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING OVER
ROUGHLY THE NORTHEAST HALF OF THE CWFA. BY LATE EVENING MAINLY DRY
CONDITIONS ARE EXPECTED WITH LITTLE IF ANY CONVECTION AFTER
MIDNIGHT.
08
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 229 AM CDT FRI MAY 17 2013
MAIN CHALLENGE IS THE PROBABLE SEVERE WEATHER RISKS SUN/MON.
OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH ALL SOLUTIONS
HAVING DIFFICULTY WITH ONGOING CENTRAL IOWA MCS EVENT. COUPLED
WITH BL DEWPOINT ISSUES SUGGEST AGAIN USE OF CONCEPTUAL
PRECIPITATION EVOLUTION TOOLS DERIVED FROM THE FORCING OF A BLEND
OF GEM-NH /HI-RES ECMWF/GFS. THIS SUPPORTS A DECENT RISK OF SEVERE
STORMS SUN/MON WITH PHASING AND CONVECTIVE ISSUES THAT SHOULD
BETTER CLARIFIED IN THE NEXT 24 HOURS. HIGHER END SEVERE STORM
EVENTS FOR REGION APPEAR MARGINAL ATTM FOR THE AREA WITH LOW/MODERATE
SEVERE EVENTS SUGGESTED ATTM.
SATURDAY...MINOR CHANGES WITH AREA LIKELY PARTLY SUNNY AND DRY AHEAD
OF SEASONABLY STRONG UPPER LEVEL SYSTEM MOVING INTO WEST CENTRAL
PLAINS. WARM AND A BIT HUMID WITH HIGHS IN THE LOWER 80S AND LOWS
MOSTLY IN THE LOWER 60S WITH DEWPOINTS 60-64F. SOME PATCHY FOG
POSSIBLE WITH ANY CLEARING FOR LATER SHIFTS TO CONSIDER.
SUNDAY AND MONDAY. GOOD SHEAR AND AT LEAST MODERATE INSTABILITY
SUPPORT ONE OR MORE CONVECTIVE EVENTS SUGGESTED WITH ENVIRONMENT
MOSTLY FAVORABLE FOR CONVECTIVE BOWING SEGMENTS ATTM. SEVERE
WEATHER AREAL TOOL AND BLEP/HELP ALGORITHMS SUGGEST WITH T/TDS
AOA 83/63 OF 60-70 MPH STRAIGHT LINE WINDS AND SOME HAIL THAT
COULD APPROACH 1.75 INCHES WITH WBZ OF ~11K AGL AND SBCAPE OF
2000-3000 J/KG. IF ANY WAVE FORMS IN LATE PM/EVENING THERE IS A
RISK OF ISOLATED TORNADOES BUT THIS APPEARS MARGINAL DUE TO
CURRENT JET STRUCTURE AND TIMING. HIGHS SUGGESTED BASED ON PARTLY
SUNNY SKIES SHOULD BE IN THE LOWER/MIDDLE 80S AND MINS MOSTLY IN
THE MIDDLE 60S. PW/S OF 1.25+ INCHES DO SUPPORT LOCALLY HEAVY
RAINFALL WITH ANY TRAINING OF STORMS. POPS IN THE LIKELY CATEGORY TO THE
MID/HIGH CHANCE WITH TIMING MAIN ISSUE. LOCAL FORCING AND HEAVY
RAIN TECHNIQUES DO SUPPORT MOST AREAS TO PICK UP AN INCH OR MORE
OF RAIN WITH PASSAGE OF UPPER LEVEL SYSTEM OVER NEXT 96+ HOURS.
TUESDAY...A CHALLENGE WITH WAVE BASED ON CONVECTION FIRING OVER
SOUTHERN PLAINS THE KEY ISSUE. JET STRUCTURE SUPPORTS DECENT RAIN
EVENT WITH LOTS OF CLOUDS AND THIS WOULD IMPACT HIGH TEMPERATURES
FOR LATER SHIFTS THAT MAY NEED LOWERING OVER CENTRAL AND SE SECTIONS.
POPS MAY NEED RAISING AS WELL BY 10-20 PERCENT WITH MODERATE TO
LOW END HEAVY AMOUNTS SUGGESTED. CONVECTIVE FEEDBACK QUESTION
SHOULD BE CLARIFIED MORE IN THE NEXT 24-36 HOURS. TUESDAY
NIGHT...UPPER LOW MOVES INTO AREA WITH CHANCE OF LOW TOP CONVECTION
OF SHOWERS AND BRIEF THUNDERSTORMS. MINS OF 55-60F WITH TEMPS
POSSIBLY A BIT TOO COOL IN FAR SE SECTIONS WITH CLOUDS.
WEDNESDAY AND THURSDAY...UPPER LOW TO SLIDE SLOWLY EAST WITH CHANCE
SHOWERS AND POSSIBLY ISOLATED THUNDER WITH PARTLY TO MOSTLY CLOUDY
SKIES. HIGH TEMPERATURES 67-77F SUGGESTED. LOWS IN THE 50S WED AM
AND MID/UPPER 40S TO LOWER 50S SE SECTIONS THU AM. SEASONABLY STRONG
CANADIAN HIGH PRESSURE TO THEN DOMINATE AND KEEP AREA COOL WITH LOW
DEWPOINTS AND BELOW NORMAL INTO NEXT WEEKEND.
NICHOLS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1214 PM CDT FRI MAY 17 2013
SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON...
PRODUCING ISOLATED HEAVY RAINFALL AND LOCAL MVFR CIGS AND VSBYS.
OUTSIDE OF THUNDERSTORMS...VFR CONDITIONS WILL CONTINUE THROUGH THE
EVENING. OVERNIGHT AREAS OF FOG AND IFR CIGS ARE EXPECTED TO SETTLE
ACROSS THE REGION...IMPROVING ONCE AGAIN TO VFR AFTER 14Z/18.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...DMD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
701 AM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 649 AM CDT FRI MAY 17 2013
THE NOCTURNAL MCS WILL CONTINUE MOVING EAST FROM MN INTO WI THIS
MORNING BEFORE SLOWLY DISSIPATING. BOUNDARIES LEFT OVER FROM THAT
CONVECTION WILL BE THE PRIMARY FOCUS FOR DIURNAL CONVECTION TODAY.
MCS AND LIFT TOOLS PER RAP TRENDS SHOW THE THETA E GRADIENT AND
ASSOCIATED CONVERGENCE/LIFT IS JUST NORTH OF THE AREA. THUS DRY
CONDITIONS ARE EXPECTED THROUGH MID DAY ACROSS THE AREA. THE
CURRENT FCST HAS CONVECTION DEVELOPING IN THE AFTERNOON BUT IT IS
DEPENDENT ON WHEN CONVECTIVE TEMPERATURE IS ACHIEVED. IF THE RAP IS
CORRECT WE WOULD REMAIN BELOW CONVECTIVE TEMPERATURE. HOWEVER...
THE RAP TRENDS DO SHOW AREAS OF CONVERGENCE DEVELOPING DURING THE
AFTERNOON ALONG WITH WEAK THETA E GRADIENTS.
SO...ISOLATED TO SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON
WITH THE NORTH THIRD MORE FAVORED DUE TO THE PROXIMITY OF THE
FRONTAL BOUNDARY. STORMS WILL BE SLOW MOVING DUE TO THE UPPER
RIDGE SO ANY THUNDERSTORM THAT DEVELOPS WILL HAVE THE POTENTIAL TO
PRODUCE VERY LOCALIZED HEAVY RAINFALL OF AN INCH OR MORE. ..08..
&&
.SYNOPSIS...
ISSUED AT 229 AM CDT FRI MAY 17 2013
06Z SFC ANALYSIS HAS A WEAK LOW IN WESTERN IOWA JUST EAST OF KSUX
AND ANOTHER IN SOUTHERN SOUTH DAKOTA. AN EAST/WEST FRONTAL BOUNDARY
RAN FROM NORTHERN OHIO...THROUGH CENTRAL INDIANA...AND TO THE LOW
NEAR KSUX. FLOW OFF LAKE MICHIGAN HAD DEW POINTS RANGING FROM THE
UPPER 30S NORTH OF THE FRONT TO 50S AND LOW 60S SOUTH OF THE FRONT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 229 AM CDT FRI MAY 17 2013
THE CURRENT CONVECTION ON RADAR IS OCCURRING ALONG A THETA E
GRADIENT AND MOISTURE/TEMPERATURE GRADIENTS FROM THE 850MB FRONT.
MOST OF THE AREA WILL REMAIN DRY THROUGH SUNRISE EXCEPT FOR VERY
ISOLATED CONVECTION IN THE HWY 20 CORRIDOR.
THE MORNING HOURS ARE EXPECTED TO BE MAINLY DRY WITH PASSING CLOUDS
AS THE THETA E GRADIENT MOVES NORTH INTO WISCONSIN. DIFFERENTIAL
HEATING COMBINED WITH AN APPROACHING VORT MAX SHOULD RESULT IN
ISOLATED TO SCATTERED CONVECTION DEVELOPING BY LATE MORNING IN THE
EASTERN CWFA.
DURING THE AFTERNOON HOURS...ISOLATED TO SCATTERED CONVECTION WILL
EXPAND TO MOST OF THE CWFA AS CONVECTIVE TEMPERATURES ARE REACHED.
THE PROXIMITY OF THE UPPER RIDGE MEANS THAT STEERING CURRENTS FOR
THE CONVECTION ARE VERY WEAK. THUS THOSE AREAS THAT DO SEE RAIN THIS
AFTERNOON WILL HAVE THE POTENTIAL TO SEE LOCALLY HEAVY RAINFALL.
CONVECTION WILL SLOWLY DIMINISH WITH SUNSET BUT ISOLATED TO
SCATTERED CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING OVER
ROUGHLY THE NORTHEAST HALF OF THE CWFA. BY LATE EVENING MAINLY DRY
CONDITIONS ARE EXPECTED WITH LITTLE IF ANY CONVECTION AFTER
MIDNIGHT.
08
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 229 AM CDT FRI MAY 17 2013
MAIN CHALLENGE IS THE PROBABLE SEVERE WEATHER RISKS SUN/MON.
OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH ALL SOLUTIONS
HAVING DIFFICULTY WITH ONGOING CENTRAL IOWA MCS EVENT. COUPLED
WITH BL DEWPOINT ISSUES SUGGEST AGAIN USE OF CONCEPTUAL
PRECIPITATION EVOLUTION TOOLS DERIVED FROM THE FORCING OF A BLEND
OF GEM-NH /HI-RES ECMWF/GFS. THIS SUPPORTS A DECENT RISK OF SEVERE
STORMS SUN/MON WITH PHASING AND CONVECTIVE ISSUES THAT SHOULD
BETTER CLARIFIED IN THE NEXT 24 HOURS. HIGHER END SEVERE STORM
EVENTS FOR REGION APPEAR MARGINAL ATTM FOR THE AREA WITH LOW/MODERATE
SEVERE EVENTS SUGGESTED ATTM.
SATURDAY...MINOR CHANGES WITH AREA LIKELY PARTLY SUNNY AND DRY AHEAD
OF SEASONABLY STRONG UPPER LEVEL SYSTEM MOVING INTO WEST CENTRAL
PLAINS. WARM AND A BIT HUMID WITH HIGHS IN THE LOWER 80S AND LOWS
MOSTLY IN THE LOWER 60S WITH DEWPOINTS 60-64F. SOME PATCHY FOG
POSSIBLE WITH ANY CLEARING FOR LATER SHIFTS TO CONSIDER.
SUNDAY AND MONDAY. GOOD SHEAR AND AT LEAST MODERATE INSTABILITY
SUPPORT ONE OR MORE CONVECTIVE EVENTS SUGGESTED WITH ENVIRONMENT
MOSTLY FAVORABLE FOR CONVECTIVE BOWING SEGMENTS ATTM. SEVERE
WEATHER AREAL TOOL AND BLEP/HELP ALGORITHMS SUGGEST WITH T/TDS
AOA 83/63 OF 60-70 MPH STRAIGHT LINE WINDS AND SOME HAIL THAT
COULD APPROACH 1.75 INCHES WITH WBZ OF ~11K AGL AND SBCAPE OF
2000-3000 J/KG. IF ANY WAVE FORMS IN LATE PM/EVENING THERE IS A
RISK OF ISOLATED TORNADOES BUT THIS APPEARS MARGINAL DUE TO
CURRENT JET STRUCTURE AND TIMING. HIGHS SUGGESTED BASED ON PARTLY
SUNNY SKIES SHOULD BE IN THE LOWER/MIDDLE 80S AND MINS MOSTLY IN
THE MIDDLE 60S. PW/S OF 1.25+ INCHES DO SUPPORT LOCALLY HEAVY
RAINFALL WITH ANY TRAINING OF STORMS. POPS IN THE LIKELY CATEGORY TO THE
MID/HIGH CHANCE WITH TIMING MAIN ISSUE. LOCAL FORCING AND HEAVY
RAIN TECHNIQUES DO SUPPORT MOST AREAS TO PICK UP AN INCH OR MORE
OF RAIN WITH PASSAGE OF UPPER LEVEL SYSTEM OVER NEXT 96+ HOURS.
TUESDAY...A CHALLENGE WITH WAVE BASED ON CONVECTION FIRING OVER
SOUTHERN PLAINS THE KEY ISSUE. JET STRUCTURE SUPPORTS DECENT RAIN
EVENT WITH LOTS OF CLOUDS AND THIS WOULD IMPACT HIGH TEMPERATURES
FOR LATER SHIFTS THAT MAY NEED LOWERING OVER CENTRAL AND SE SECTIONS.
POPS MAY NEED RAISING AS WELL BY 10-20 PERCENT WITH MODERATE TO
LOW END HEAVY AMOUNTS SUGGESTED. CONVECTIVE FEEDBACK QUESTION
SHOULD BE CLARIFIED MORE IN THE NEXT 24-36 HOURS. TUESDAY
NIGHT...UPPER LOW MOVES INTO AREA WITH CHANCE OF LOW TOP CONVECTION
OF SHOWERS AND BRIEF THUNDERSTORMS. MINS OF 55-60F WITH TEMPS
POSSIBLY A BIT TOO COOL IN FAR SE SECTIONS WITH CLOUDS.
WEDNESDAY AND THURSDAY...UPPER LOW TO SLIDE SLOWLY EAST WITH CHANCE
SHOWERS AND POSSIBLY ISOLATED THUNDER WITH PARTLY TO MOSTLY CLOUDY
SKIES. HIGH TEMPERATURES 67-77F SUGGESTED. LOWS IN THE 50S WED AM
AND MID/UPPER 40S TO LOWER 50S SE SECTIONS THU AM. SEASONABLY STRONG
CANADIAN HIGH PRESSURE TO THEN DOMINATE AND KEEP AREA COOL WITH LOW
DEWPOINTS AND BELOW NORMAL INTO NEXT WEEKEND.
NICHOLS
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 649 AM CDT FRI MAY 17 2013
VFR WX WILL BE SEEN THROUGH 12Z/18. NEW CONVECTION WILL DVLP AFT
18Z/17 BUT THE PROBABILITY OF A SHRA OR TSRA AFFECTING A TAF SITE
IS 15 PERCENT. VCTS OR VCSH WAS INCLUDED IN THE 12Z TAFS TO
REFLECT THE POTENTIAL FOR NEARBY CONVECTION FROM 20Z/17 TO 03Z/18.
IF A SHRA/TSRA AFFECTS A TAF SITE CIGS SHOULD REMAIN VFR. VSBYS
MAY DROP TO MVFR OR IFR FROM HEAVY RAIN. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
341 AM EDT FRI MAY 17 2013
.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL OUT TO THE SOUTH THROUGH THIS
WEEKEND...AS HIGH PRESSURE ANCHORS ITSELF ACROSS THE NORTH
ATLANTIC. THE FRONTAL BOUNDARY WILL RETURN TO THE NORTH AS A WARM
FRONT EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK PSEUDO-STATIONARY FRONTAL BOUNDARY HAS FINALLY DRIFTED SOUTH
OF THE MASON-DIXON LINE AND IS HELPING TO CLEAR OUT THE AREA
OVERNIGHT. THIS BOUNDARY CONTINUES TO STRETCH FROM THE ATLC
COAST...DIRECTLY WEST TO THE PLAINS. NOW W/ THE BOUNDARY SET-UP OVER
THE REGION AND NO DISCERNIBLE SYSTEMS COMING DOWN THE PIKE IN THE
NEXT COUPLE OF DAYS...IT WILL RESIDE JUST SOUTH OF THE AREA AND BE
THE FOCUS FOR DAILY WEAKLY-FORCED CONVECTION DEPENDING ON WHERE IT
IS LOCATED.
PRECIP ALONG THIS BOUNDARY AS ALL BUT ENDED OVER THE PAST FEW HRS
AND CONDITIONS WILL BE STABLE UNTIL DAWN. LOCALIZED HRRR CONTINUES
TO DEVELOP TERRAIN CONVECTION LATER TODAY. ISOLATED SHOWERS AND
TSTMS WILL LIKELY DEVELOP THIS AFTN/EVE FROM A LIGHT ESE FLOW
BANKING INTO THE ERN SIDES OF THE HIGHEST TERRAIN OF THE CENTRAL
APPALACHIANS...TAPERING OFF TOWARD THE SHEN VLY. STEERING FLOW WILL
BE INCREDIBLY LIGHT...A MEAN 10-15KT FLOW ALL THE WAY UP TO THE
UPPER LEVELS...WON`T TAKE MUCH OF THIS ACTIVITY EWD. WEAK OUTFLOW
BOUNDARIES WILL HAVE TO DO THAT IN ORDER TO SPREAD POPS MUCH FURTHER
EAST.
CUT BACK ON POPS OVERNIGHT FOR THE ERN HALF OF THE REGION.
DEPICTIONS FROM THE NAM/GFS FOR A LOCALIZED BATCH OF PRECIP
STREAMING ACROSS A BULK OF THE CWA DURING THE PREDAWN HRS SAT STILL
A BIT SUSPECT. PLACEMENT OF SUCH A SMALL-SCALE UPPER WAVE CAUGHT IN
THE FLOW STILL A BIT TOO FAR OUT TO PLACE IN THE CURRENT FORECAST.
TEMPS TODAY WILL BE EVEN MORE MODERATED TODAY FROM YESTERDAY W/
DRIER AIR AND A LIGHT BUT STEADY NE BREEZE COMING DOWN THE I-95
CORRIDOR FOR MUCH OF THE DAY. MOST AREAS WILL PEAK IN THE U70S...W/
A FEW LOCALES HITTING 80 LATE THIS AFTN. OVERNIGHT LOWS WILL BE
SIMILAR TO THE CURRENT OVERNIGHT PERIOD...TEMPS DROPPING INTO THE
U50S/L60S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
FRONTAL BOUNDARY WILL REMAIN STALLED OUT TO THE SOUTH THIS
WEEKEND...AS HIGH PRESSURE ANCHORS ITSELF OFF THE NORTHEAST
COAST AND NORTH ATLANTIC.
RESULT WILL BE AN EAST OR SOUTHEAST FLOW IN THE LOW LEVELS WHICH
WILL PROMOTE CLOUDY SKIES MUCH OF THE TIME AND ALSO TEMPER WARMING.
THE DEGREE TO WHICH WARMING IS TEMPERED DIFFERS BETWEEN THE NAM AND
GFS DERIVED MOS GUIDANCE...WITH THE GFS BEING LOWER BY 10 DEGREES
IN SOME CASES FOR MAXIMA. DIFFERENCES ARE LIKELY EXPLAINED BY THE
PRESENCE OF PRECIPITATION OR LACK THEREOF.
THE GFS IS MUCH MORE AGGRESSIVE BRINGING MEASURABLE RAINFALL ACROSS
THE CWA WHILE THE NAM IS MORE CONSERVATIVE. SREFS FORMS A NICE
COMPROMISE...FOCUSING SHOWERS /AND PERHAPS A FEW THUNDERSTORMS/
ACROSS THE SOUTHWEST PORTION OF THE CWA SATURDAY AND THEN
SPREADING CHANCES /OR LIKELIHOODS/ FOR RAINFALL NORTHEAST INTO
SUNDAY. MOISTURE IS CERTAINLY THERE...WHETHER ISENTROPIC LIFT
WORKS THIS FAR NORTH AND WHETHER THERE ARE SHORTWAVES IN 500 MB
FLOW IS SOMEWHAT IN QUESTION.
FOR TEMPERATURES...HAVE TAKEN A BLEND OF BIAS CORRECTED MAV/MET AND
ALSO ECMWF WHICH FAVORS LOWER 70S ACROSS MUCH OF THE AREA FOR
MAXIMA. NO MATTER HOW ONE SLICES IT...MAXIMA OVER THE WEEKEND WILL
LIKELY BE BELOW NORMAL WITH NEAR TO SLIGHTLY ABOVE NORMAL MINIMA.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
FRONTAL BOUNDARY WILL LIFT BACK TO THE NORTH AS WARM FRONT EARLY
NEXT WEEK...MOST LIKELY LATE MONDAY INTO EARLY TUESDAY AND PLACING
THE CWA IN A WARM SECTOR DURING THE MIDDLE OF THE WEEK. THIS SHOULD
BRING LOW LEVEL SOUTH-SOUTHWEST FLOW WHICH WILL KEEP MOISTURE ACROSS
THE AREA AND SOME SURFACE-BASED INSTABILITY. THEREFORE FORECAST
REFLECTS A CHANCE OF MAINLY DIURNAL CONVECTION EACH DAY. FRONTAL
BOUNDARY MAY APPROACH ON THURSDAY.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
A WEAK FRONTAL BOUNDARY SINKING SWD THRU THE AREA THIS MORNING.
THIS FEATURE WILL STABILIZE MUCH OF THE AREA...W/ DRIER AIR
SPREADING ACROSS THE REGION AND CLOUDS DISSIPATING ACROSS THE
AREA. THE SWRN QUADRANT OF THE CWA...AREAS TO THE SOUTH AND WEST
OF KCHO WILL REMAIN THE TARGET FOR ISOLATED SHOWERS...ANY FOG AND
MID CLOUDS TODAY. OUTSIDE OF THIS AREA...ONLY A FEW BATCHES OF
MID/UPPER CLOUD DECKS TODAY...SO SOLID VFR CONDITIONS THRU THE TAF
PERIOD. A LIGHT NELY FLOW THIS MRNG WILL EVENTUALLY SWITCH SELY
LATER TONIGHT.
EAST-SOUTHEAST FLOW DEVELOPS THIS WEEKEND. IT IS BECOMING MORE
LIKELY THAT A PERIOD OF MVFR/IFR CIGS WILL DEVELOP SATURDAY NIGHT
INTO EARLY SUNDAY AND AGAIN SUNDAY NIGHT INTO EARLY MONDAY BEFORE A
STALLED FRONTAL BOUNDARY WORKS BACK TO THE NORTH AS A WARM FRONT
EARLY NEXT WEEK. PRECIPITATION WOULD LIKELY BE SHOWERS OVER THE
WEEKEND...THEN THUNDERSTORMS WILL BE POSSIBLE EARLY TO MID NEXT WEEK
IN THE WARM SECTOR.
&&
.MARINE...
LIGHT WINDS TODAY AND TONIGHT...AS A WEAK FRONTAL BOUNDARY SLIDES
SOUTHWARD. BEHIND THE FRONT...WINDS WILL COME DOWN FROM THE NE FOR
THE MRNG HAS AND EVENTUALLY TURN SELY LATER TODAY AS THE BOUNDARY
DROPS SOUTH OF THE TP/CHES BAY CONFLUENCE REGION.
FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE WATERS THROUGH THE WEEKEND
BEFORE LIFTING BACK TO THE NORTH EARLY NEXT WEEK. EAST-SOUTHEAST
FLOW IS EXPECTED BUT WITH A RELATIVELY WEAK GRADIENT WINDS ARE
GENERALLY EXPECT TO REMAIN BELOW SCA CRITERIA. WINDS TURN TO THE
SOUTH EARLY NEXT WEEK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GMS/BPP
NEAR TERM...GMS
SHORT TERM...BPP
LONG TERM...BPP
AVIATION...GMS/BPP
MARINE...GMS/BPP
AREA FORECAST DISCUSSION
NWS GAYLORD MI
125 PM EDT FRI MAY 17 2013
.SYNOPSIS...
ISSUED AT 352 AM EDT FRI MAY 17 2013
HIGH PRESSURE WILL REMAIN IN CONTROL OF NORTHERN MICHIGANS WEATHER
THROUGH TODAY...RESULTING IN DRY WEATHER UNDER PARTLY SUNNY SKIES
AND SEASONABLE TEMPERATURES. WARM AND MOIST AIR PRESSING INTO THE
MIDWEST AND GREAT LAKES WILL BRING A CHANCE FOR SHOWERS TO THE
NORTH WOODS OVER THE WEEKEND...MAINLY ON SATURDAY.
&&
.UPDATE...
ISSUED AT 116 PM EDT FRI MAY 17 2013
WELL...HIGH RES RUNS HAVE SHOWN THEIR USEFULNESS...PEGGING
DECAYING MCS REMNANTS OVERSPREADING AREAS ALONG AND SOUTH OF M-72
THIS AFTERNOON. RADAR AND SURFACE TRENDS NO DOUBT BEAR THIS
OUT...WITH LIGHT RAIN REPORTED AT FKS...MBL...AND CAD WITHIN THE
LAST HOUR. THIS LIGHT RAIN SHOULD CONTINUE TO SPREAD EAST...AND
HAVE SIGNIFICANTLY ADJUSTED FORECAST TO SHOW THESE TRENDS. COOL
EAST FLOW AND EXTENSIVE CLOUDS ACROSS NORTHERN LOWER ALSO PLAYING
HAVOC WITH TEMPERATURE TRENDS. READINGS ALREADY WELL SHORT OF WHAT
WAS EARLIER ANTICIPATED. HAVE ADJUSTED THESE DOWNWARD...ALTHOUGH
WHERE RAIN PERSISTS...MAY NOT YET BE COOL ENOUGH.
UPDATE ISSUED AT 936 AM EDT FRI MAY 17 2013
INCREASINGLY CHALLENGING FORECAST DEVELOPING FOR TODAY. UPSTREAM
REMNANT MCS ON LEADING EDGE OF THETA-E ADVECTION/NOSE OF LOW LEVEL
JET CONTINUES TO DRIVE EAST ACROSS SOUTHERN WISCONSIN...WITH SOME
LEADING EDGE RETURNS SPILLING INTO SOUTHWEST SECTIONS OF OUR AREA
(EVEN SOME EVIDENCE OF MID LEVEL FGEN HELPING MAINTAIN/EXPAND THESE
LEADING EDGE SHOWERS). LOW LEVELS REMAIN DRY...AND JUST HAD FIRST
REPORTS OF RAIN REACHING THE SURFACE AT CADILLAC. HAVE ADJUSTED
FORECAST A TOUCH MORE PESSIMISTICALLY SOUTH OF TRAVERSE
CITY...ALTHOUGH TRENDS SUGGEST PERHAPS NOT PESSIMISTICALLY ENOUGH.
LATEST HIGH RES HRRR SOMEWHAT DISCONCERTING...DRIVING DECAYING MCS
ACROSS THE SOUTH HALF OF THE AREA THIS AFTERNOON...PRODUCING RATHER
WIDESPREAD LIGHT SHOWERS. PERUSAL OF OTHER GUIDANCE AND MODEL
DERIVED SOUNDINGS SUGGEST OTHERWISE...WITH DEEP LOW LEVEL DRY LAYER
AND LOSS OF DYNAMICS ESSENTIALLY FULLY DECAYING THIS ACTIVITY BEFORE
IT REACHES OUR AREA. THAT SAID...RADAR RETURNS MORE THAN
OMINOUS...AND DEFINITE FUTURE CHANGES MORE THAN EXPECTED. MORE
CLOUDS/RAIN WOULD ALSO MEAN SIGNIFICANTLY COOLER TEMPERATURES ACROSS
THE SOUTH. WILL CONTINUE TO MONITOR.
UPDATE ISSUED AT 606 AM EDT FRI MAY 17 2013
FORECAST APPEARS ON TRACK FOR THE MOMENT. SUBSTANTIAL HIGH CLOUDS
FROM UPSTREAM CONVECTION HAVE OVERSPREAD MUCH OF THE CWA...
ESPECIALLY NRN LOWER MICHIGAN. SATELLITE TRENDS REVEAL ABUNDANT
HIGHER CLOUD COVER UPSTREAM THAT WILL CONTINUE TO STREAM THROUGH
THE REGION TODAY. THUS PARTLY SUNNY TO OCCASIONALLY MOSTLY CLOUDY
SKIES SHOULD WORK OUT.
OTHERWISE...QUITE A FEW LOCATIONS ARE IN THE UPPER 30S WITH A FEW
SPOTS COLDER (PLN IS 32F). WARMEST LOCATIONS ARE IN THE SW
COUNTIES (TVC/FKS/MBL...ETC). CAN PROBABLY SAFELY TRIM THOSE
COUNTIES OUT OF THE FREEZE ADVISORY EARLY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 352 AM EDT FRI MAY 17 2013
OVERVIEW: FAIRLY PROGRESSIVE FLOW PATTERN ACROSS THE CONUS CURRENTLY
BUT STARTING TO BECOME MORE AMPLIFIED AS TROUGHINESS DEEPENS ALONG
THE WEST COAST...AND DOWNSTREAM RIDGING BUILDS THROUGH THE PLAINS
AND INTO THE GREAT LAKES. RIDGING GRADUALLY BUILDS INTO THE GREAT
LAKES HEADING THROUGH THE WEEKEND SIGNALING WARMER DAYS AHEAD.
MEANWHILE...HIGH PRESSURE HAS NUDGED IT/S WAY DOWN OUT OF ONTARIO
AND INTO THE WESTERN GREAT LAKES. ONGOING MCS ACTIVITY TO OUR
SOUTHWEST ACROSS IOWA...BUT WILL STAY WELL AWAY FROM US AS
MOISTURE/INSTABILITY REMAINS DISPLACED WELL OFF TO OUR WEST AND SOUTH.
TODAY...HIGH PRESSURE AND ANTECEDENT DRY AIRMASS WILL CONTINUE TO
DOMINATE THE REGION WITH NO PRECIP ANTICIPATED. HOWEVER...THERE IS
QUITE A BIT OF MID AND HIGH CLOUD COVER UPSTREAM FROM ONGOING
CONVECTION AS WELL AS INCREASING WARM ADVECTION ACROSS THE PLAINS.
THUS...WILL SEE VARIOUS ROUNDS OF MID AND HIGH CLOUD SLIDING THROUGH
THE REGION...LEADING TO PARTLY CLOUDY TO OCCASIONALLY MOSTLY CLOUDY
SKIES. TEMPERATURES...A LITTLE WARMER AS COMPARED TO THURSDAY WITH
HIGHS RANGING FROM THE MID 60S TO LOWER 70S.
FIRE WEATHER CONCERNS...DRY ANTECEDENT CONDITIONS PERSIST AND EXPECT
INLAND SFC DEWPOINTS WILL DIP INTO THE LOWER 30S DURING THE
AFTERNOON LIKE THURSDAY WITH MINIMUM RH VALUES GOING BELOW 25
PERCENT. HOWEVER...TEMPS WILL LARGELY REMAIN BELOW 75 FOR MOST AREAS
AND WINDS WILL BE FAIRLY LIGHT (UNDER 10 MPH). YES IT WILL BE DRY
BUT WITHOUT DECENT WIND...WILL NOT HAVE ELEVATED FIRE DANGER
MENTIONED IN THE HWO FOR TODAY.
TONIGHT...WARM AND MOIST AIR (HIGH THETA-E) BUILDS THROUGH THE
PLAINS AND THE UPPER MIDWEST THROUGH THE COURSE OF THE NIGHT WITH
THE STRONGEST SURGE/FORCING OCCURRING ACROSS THE NRN PLAINS AND UPPER
MIDWEST WHERE ONE OR MORE CONVECTIVE SYSTEMS WILL LIKELY BE ONGOING
OR DEVELOP. HERE AT HOME...NOT SO IMPRESSED. NW-SE ORIENTED THETA-E
GRADIENT WILL BE INCHING UP THROUGH STATE THROUGH THE COURSE OF THE
NIGHT. BUT AGAIN...MUCH STRONGER LOW LEVEL FLOW AND RESULTING
FORCING (MOIST CONVERGENCE) WILL REMAIN WELL WEST-NORTHWEST OF THE
CWA WHERE MOST CONVECTIVE ACTIVITY WILL BE CONFINED. SUPPOSE ITS
PLAUSIBLE WE GET A FEW ELEVATED SHOWERS TO DEVELOP ALONG THE
ADVANCING THETA-E GRADIENT ALTHOUGH LAPSE RATES ALOFT ARE JUST NOT
THAT SUPPORTIVE OF CONVECTION. IN THE END...FOR CONTINUITY AND
COLLABORATION WITH SURROUNDING OFFICES...DECIDED TO MAINTAIN CHANCE
POPS FOR SHOWERS OVER NW LOWER MICHIGAN OVERNIGHT BUT HAVE TRIMMED
POPS BACK TO 30 PERCENT OR LESS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 352 AM EDT FRI MAY 17 2013
A WARMER AND PROGRESSIVELY MORE MOIST SOUTHEASTERLY FLOW WILL LEAD
TO CHANCES FOR SHOWERS THIS WEEKEND. THERE WILL BE CHANCES FOR
SHOWERS AND EVEN THUNDERSTORMS EARLY NEXT WEEK WHICH WILL BECOME
LIKELY BY THE MIDDLE OF NEXT WEEK...AS A CUTOFF UPPER TROUGH
APPROACHES FROM OUR SOUTHWEST. FINALLY...CONDITIONS MOST LIKELY DRY
OUT BY THURSDAY AS THIS SYSTEM RETREATS TO THE SOUTHEAST. THE MAIN
LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND HOW MUCH IT WILL
WARM UP THIS WEEKEND INTO EARLY NEXT WEEK.
SATURDAY AND SUNDAY...MODELS ARE ONLY IN FAIR AGREEMENT ON THE
TIMING AND AMOUNT OF MOISTURE ADVECTION INTO THE REGION AS THETA-E
RIDGING APPROACHES THE FORECAST AREA BUT WEAKENS AS IT DOES SO. THIS
IS IN RESPONSE TO A DECAYING AREA OF LOW PRESSURE MOVING BY TO THE
NORTHWEST. IT IS STILL UNCERTAIN IF IT WILL MOISTEN UP ENOUGH ACROSS
NORTHERN MICHIGAN TO ACTUALLY RAIN...AS THE MAIN ACTION LOOKS TO
REMAIN TO OUR WEST. SO WILL BACK OFF ON POPS TO SLIGHT AND LOW
CHANCES FOR SHOWERS. HIGHS SATURDAY RANGING FROM THE MIDDLE 60S TO
MIDDLE 70S...WITH THE WARMER 70S TO LOWER 80S ON SUNDAY EXPECTED.
LOWS SATURDAY NIGHT IN THE MIDDLE 40S TO LOWER 50S.
MONDAY THROUGH THURSDAY...SHOWERS AND THUNDERSTORM CHANCES INCREASE
MONDAY THEN BECOME LIKELY MONDAY NIGHT INTO WEDNESDAY AS A CUTOFF
UPPER LEVEL TROUGH AND WARM FRONT APPROACH FROM THE SOUTHWEST.
EXTENDED MODELS THEN VARY ON THE TIMING OF DRYING FROM THE
NORTH...BUT WILL PENCIL THURSDAY IN AS A DRY DAY AS THIS SYSTEM IS
SHOWN TO SLOWLY RETREAT TO OUR SOUTHEAST. REMAINING WARM WITH HIGHS
IN THE 70S TO LOWER 80S MONDAY...FOLLOWED BY A SLOW COOLING TREND
WITH TEMPERATURES ENDING UP IN THE UPPER 50S TO LOWER 60S FOR HIGHS
BY THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 116 PM EDT FRI MAY 17 2013
VFR CONDITIONS EXPECTED. EXTENSIVE DECK OF HIGH AND MID LEVEL
CLOUDS WILL CONTINUE TO AFFECT ALL TAF SITES RIGHT INTO SATURDAY
MORNING. LIGHT RAINS ALREADY OCCURRING AT KMBL...AND SHOULD
CONTINUE TO DO SO FOR THE NEXT FEW HOURS. RAINS MAY EDGE NORTH TO
TVC LATER THIS AFTERNOON...ALTHOUGH WITH NO IMPACT TO VIS. LIGHT
WINDS WILL REMAIN ACROSS THE AREA.
&&
.MARINE...
ISSUED AT 352 AM EDT FRI MAY 17 2013
LIGHT WINDS/LOW WAVES WILL PREVAIL ON THE LAKES TODAY AND TONIGHT
WITH NO MARINE HEADLINES NEEDED. SOUTH-SOUTHEAST FLOW INCREASES
SATURDAY AND SATURDAY NIGHT AND A HANDFUL OF SMALL CRAFT ADVISORIES
MAY BE NEEDED. AT THAT TIME.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...AS
SHORT TERM...BA
LONG TERM...AS
AVIATION...MB
MARINE...BA
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
104 PM EDT FRI MAY 17 2013
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 334 AM EDT FRI MAY 17 2013
MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST
TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO
FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND
EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE
AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND
SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL
WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK.
&&
.UPDATE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013
PRECIPITATION MOVING OFF THE WI SHORELINE HAS BEEN SLOW TO
DIMINISH. GFS 06Z RUN SEEMED TO HAVE A BETTER HANDLE ON THE
PRECIPITATION THAN THE NEW NAM. HRRR 12Z RUN AND OLD GFS PAINT
PRECIPITATION ACROSS MUCH OF NRN ZONES...NORTH OF MKG TO GRR WITH
PRECIPITAITON THIS AFTERNOON. WILL BUMP UP POPS AND LOWER
TEMPERATURES FOR THIS REGION.
UPDATE ISSUED AT 949 AM EDT FRI MAY 17 2013
ADDED A FEW RAIN SHOWERS TO THE FORECAST FOR LUDINGTON TO NEAR
CADILLAC. RADAR TRENDS SHOW INCREASING RETURNS AND THE OBSERVATION
OUT OF CADILLAC INDICATED THAT THE PRECIPITATION WAS REACHING THE
GROUND. AM MONITORING THE WEAKENING THUNDERSTORMS OVER IN ERN
WISCONSIN. MAY NEED TO ADD SOME PRECIPITATION TO THE MUSKEGON
FORECAST AS WELL IF THEY DO NOT WEAKEN QUICKLY ENOUGH. I DID
ADJUST TEMPERATURES DOWNWARD SLIGHTLY FOR NORTHERN ZONES DUE TO
THE CLOUDS AND PRECIPITATION.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013
THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS
THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS
DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS
TO BE ADDRESSED.
WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH
CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL
THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL
AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E
ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS
OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS
CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS
SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE
OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION.
THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD
FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE
ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID
LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF
THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST
ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO
REACH THE GROUND THROUGH THE DRIER LOWER LEVELS.
BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND
RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE
CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO
THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND
12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE
VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS
WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE
AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A
LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG
ANY BOUNDARIES.
WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS
TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN
MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE
AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST
SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD
TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM.
THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS
TIME TO JUSTIFY ADDING IN THE CHC.
.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013
LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER
LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND
EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF
THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES
ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND
ECMWF PAINT THIS SCENARIO.
AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES
STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS
APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY
FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL
BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT
AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE
PERIODS.
THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN
EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE
REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY
FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 104 PM EDT FRI MAY 17 2013
A STATIONARY FRONT OVER LOWER MICHIGAN WILL CONTINUE TO BE A FOCUS
FOR A MID CLOUD DECK THROUGH THE PERIOD. SHOWERS SEEN ON CURRENT
RADAR WILL MOSTLY STAY NORTH OF THE TAF SITES. HOWEVER A SPRINKLE
OR TWO CAN/T BE RULED OUT A KMKG BUT THE PROBABILITY WAS LOW
ENOUGH TO LEAVE OUT OF THE TAFS.
&&
.MARINE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013
EXPANDED THE MENTION OF RAIN IN THE FORECAST FOR NORTHERN MARINE
ZONES.
&&
.FIRE WEATHER...
ISSUED AT 334 AM EDT FRI MAY 17 2013
CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO
FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE
CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF
DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA...
HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG
CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO
NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES.
WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON.
DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES
A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS
SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED.
&&
.HYDROLOGY...
ISSUED AT 334 AM EDT FRI MAY 17 2013
WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY
NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT
WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER.
THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND
RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS
ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED.
THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP
PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT
ANY NOTABLE ISSUES AT THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...93
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1124 AM EDT FRI MAY 17 2013
LATEST UPDATE...
UPDATE/MARINE
.SYNOPSIS...
ISSUED AT 334 AM EDT FRI MAY 17 2013
MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST
TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO
FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND
EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE
AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND
SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL
WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK.
&&
.UPDATE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013
PRECIPITATION MOVING OFF THE WI SHORELINE HAS BEEN SLOW TO
DIMINISH. GFS 06Z RUN SEEMED TO HAVE A BETTER HANDLE ON THE
PRECIPITATION THAN THE NEW NAM. HRRR 12Z RUN AND OLD GFS PAINT
PRECIPITATION ACROSS MUCH OF NRN ZONES...NORTH OF MKG TO GRR WITH
PRECIPITAITON THIS AFTERNOON. WILL BUMP UP POPS AND LOWER
TEMPERATURES FOR THIS REGION.
UPDATE ISSUED AT 949 AM EDT FRI MAY 17 2013
ADDED A FEW RAIN SHOWERS TO THE FORECAST FOR LUDINGTON TO NEAR
CADILLAC. RADAR TRENDS SHOW INCREASING RETURNS AND THE OBSERVATION
OUT OF CADILLAC INDICATED THAT THE PRECIPITATION WAS REACHING THE
GROUND. AM MONITORING THE WEAKENING THUNDERSTORMS OVER IN ERN
WISCONSIN. MAY NEED TO ADD SOME PRECIPITATION TO THE MUSKEGON
FORECAST AS WELL IF THEY DO NOT WEAKEN QUICKLY ENOUGH. I DID
ADJUST TEMPERATURES DOWNWARD SLIGHTLY FOR NORTHERN ZONES DUE TO
THE CLOUDS AND PRECIPITATION.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013
THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS
THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS
DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS
TO BE ADDRESSED.
WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH
CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL
THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL
AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E
ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS
OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS
CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS
SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE
OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION.
THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD
FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE
ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID
LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF
THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST
ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO
REACH THE GROUND THROUGH THE DRIER LOWER LEVELS.
BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND
RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE
CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO
THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND
12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE
VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS
WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE
AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A
LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG
ANY BOUNDARIES.
WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS
TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN
MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE
AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST
SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD
TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM.
THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS
TIME TO JUSTIFY ADDING IN THE CHC.
.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013
LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER
LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND
EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF
THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES
ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND
ECMWF PAINT THIS SCENARIO.
AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES
STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS
APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY
FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL
BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT
AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE
PERIODS.
THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN
EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE
REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY
FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 749 AM EDT FRI MAY 17 2013
VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS...AS MID AND HIGH
CLOUDS DOMINATE THE DAYTIME HOURS. BASES SHOULD BE AT OR ABOVE
9000FT. CEILINGS MAY LOWER SOME TONIGHT...BUT 5000-6000FT BASES WILL
KEEP CONDITIONS AT VFR. WINDS WILL BE STEADY FROM THE EAST AT 8-12
KNOTS TODAY AND TONIGHT.
&&
.MARINE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013
EXPANDED THE MENTION OF RAIN IN THE FORECAST FOR NORTHERN MARINE
ZONES.
&&
.FIRE WEATHER...
ISSUED AT 334 AM EDT FRI MAY 17 2013
CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO
FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE
CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF
DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA...
HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG
CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO
NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES.
WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON.
DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES
A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS
SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED.
&&
.HYDROLOGY...
ISSUED AT 334 AM EDT FRI MAY 17 2013
WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY
NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT
WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER.
THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND
RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS
ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED.
THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP
PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT
ANY NOTABLE ISSUES AT THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...DUKE
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
937 AM EDT FRI MAY 17 2013
.SYNOPSIS...
ISSUED AT 352 AM EDT FRI MAY 17 2013
HIGH PRESSURE WILL REMAIN IN CONTROL OF NORTHERN MICHIGANS WEATHER
THROUGH TODAY...RESULTING IN DRY WEATHER UNDER PARTLY SUNNY SKIES
AND SEASONABLE TEMPERATURES. WARM AND MOIST AIR PRESSING INTO THE
MIDWEST AND GREAT LAKES WILL BRING A CHANCE FOR SHOWERS TO THE
NORTH WOODS OVER THE WEEKEND...MAINLY ON SATURDAY.
&&
.UPDATE...
ISSUED AT 936 AM EDT FRI MAY 17 2013
INCREASINGLY CHALLENGING FORECAST DEVELOPING FOR TODAY. UPSTREAM
REMNANT MCS ON LEADING EDGE OF THETA-E ADVECTION/NOSE OF LOW LEVEL
JET CONTINUES TO DRIVE EAST ACROSS SOUTHERN WISCONSIN...WITH SOME
LEADING EDGE RETURNS SPILLING INTO SOUTHWEST SECTIONS OF OUR AREA
(EVEN SOME EVIDENCE OF MID LEVEL FGEN HELPING MAINTAIN/EXPAND THESE
LEADING EDGE SHOWERS). LOW LEVELS REMAIN DRY...AND JUST HAD FIRST
REPORTS OF RAIN REACHING THE SURFACE AT CADILLAC. HAVE ADJUSTED
FORECAST A TOUCH MORE PESSIMISTICALLY SOUTH OF TRAVERSE
CITY...ALTHOUGH TRENDS SUGGEST PERHAPS NOT PESSIMISTICALLY ENOUGH.
LATEST HIGH RES HRRR SOMEWHAT DISCONCERTING...DRIVING DECAYING MCS
ACROSS THE SOUTH HALF OF THE AREA THIS AFTERNOON...PRODUCING RATHER
WIDESPREAD LIGHT SHOWERS. PERUSAL OF OTHER GUIDANCE AND MODEL
DERIVED SOUNDINGS SUGGEST OTHERWISE...WITH DEEP LOW LEVEL DRY LAYER
AND LOSS OF DYNAMICS ESSENTIALLY FULLY DECAYING THIS ACTIVITY BEFORE
IT REACHES OUR AREA. THAT SAID...RADAR RETURNS MORE THAN
OMINOUS...AND DEFINITE FUTURE CHANGES MORE THAN EXPECTED. MORE
CLOUDS/RAIN WOULD ALSO MEAN SIGNIFICANTLY COOLER TEMPERATURES ACROSS
THE SOUTH. WILL CONTINUE TO MONITOR.
UPDATE ISSUED AT 606 AM EDT FRI MAY 17 2013
FORECAST APPEARS ON TRACK FOR THE MOMENT. SUBSTANTIAL HIGH CLOUDS
FROM UPSTREAM CONVECTION HAVE OVERSPREAD MUCH OF THE CWA...
ESPECIALLY NRN LOWER MICHIGAN. SATELLITE TRENDS REVEAL ABUNDANT
HIGHER CLOUD COVER UPSTREAM THAT WILL CONTINUE TO STREAM THROUGH
THE REGION TODAY. THUS PARTLY SUNNY TO OCCASIONALLY MOSTLY CLOUDY
SKIES SHOULD WORK OUT.
OTHERWISE...QUITE A FEW LOCATIONS ARE IN THE UPPER 30S WITH A FEW
SPOTS COLDER (PLN IS 32F). WARMEST LOCATIONS ARE IN THE SW
COUNTIES (TVC/FKS/MBL...ETC). CAN PROBABLY SAFELY TRIM THOSE
COUNTIES OUT OF THE FREEZE ADVISORY EARLY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 352 AM EDT FRI MAY 17 2013
OVERVIEW: FAIRLY PROGRESSIVE FLOW PATTERN ACROSS THE CONUS CURRENTLY
BUT STARTING TO BECOME MORE AMPLIFIED AS TROUGHINESS DEEPENS ALONG
THE WEST COAST...AND DOWNSTREAM RIDGING BUILDS THROUGH THE PLAINS
AND INTO THE GREAT LAKES. RIDGING GRADUALLY BUILDS INTO THE GREAT
LAKES HEADING THROUGH THE WEEKEND SIGNALING WARMER DAYS AHEAD.
MEANWHILE...HIGH PRESSURE HAS NUDGED IT/S WAY DOWN OUT OF ONTARIO
AND INTO THE WESTERN GREAT LAKES. ONGOING MCS ACTIVITY TO OUR
SOUTHWEST ACROSS IOWA...BUT WILL STAY WELL AWAY FROM US AS
MOISTURE/INSTABILITY REMAINS DISPLACED WELL OFF TO OUR WEST AND SOUTH.
TODAY...HIGH PRESSURE AND ANTECEDENT DRY AIRMASS WILL CONTINUE TO
DOMINATE THE REGION WITH NO PRECIP ANTICIPATED. HOWEVER...THERE IS
QUITE A BIT OF MID AND HIGH CLOUD COVER UPSTREAM FROM ONGOING
CONVECTION AS WELL AS INCREASING WARM ADVECTION ACROSS THE PLAINS.
THUS...WILL SEE VARIOUS ROUNDS OF MID AND HIGH CLOUD SLIDING THROUGH
THE REGION...LEADING TO PARTLY CLOUDY TO OCCASIONALLY MOSTLY CLOUDY
SKIES. TEMPERATURES...A LITTLE WARMER AS COMPARED TO THURSDAY WITH
HIGHS RANGING FROM THE MID 60S TO LOWER 70S.
FIRE WEATHER CONCERNS...DRY ANTECEDENT CONDITIONS PERSIST AND EXPECT
INLAND SFC DEWPOINTS WILL DIP INTO THE LOWER 30S DURING THE
AFTERNOON LIKE THURSDAY WITH MINIMUM RH VALUES GOING BELOW 25
PERCENT. HOWEVER...TEMPS WILL LARGELY REMAIN BELOW 75 FOR MOST AREAS
AND WINDS WILL BE FAIRLY LIGHT (UNDER 10 MPH). YES IT WILL BE DRY
BUT WITHOUT DECENT WIND...WILL NOT HAVE ELEVATED FIRE DANGER
MENTIONED IN THE HWO FOR TODAY.
TONIGHT...WARM AND MOIST AIR (HIGH THETA-E) BUILDS THROUGH THE
PLAINS AND THE UPPER MIDWEST THROUGH THE COURSE OF THE NIGHT WITH
THE STRONGEST SURGE/FORCING OCCURRING ACROSS THE NRN PLAINS AND UPPER
MIDWEST WHERE ONE OR MORE CONVECTIVE SYSTEMS WILL LIKELY BE ONGOING
OR DEVELOP. HERE AT HOME...NOT SO IMPRESSED. NW-SE ORIENTED THETA-E
GRADIENT WILL BE INCHING UP THROUGH STATE THROUGH THE COURSE OF THE
NIGHT. BUT AGAIN...MUCH STRONGER LOW LEVEL FLOW AND RESULTING
FORCING (MOIST CONVERGENCE) WILL REMAIN WELL WEST-NORTHWEST OF THE
CWA WHERE MOST CONVECTIVE ACTIVITY WILL BE CONFINED. SUPPOSE ITS
PLAUSIBLE WE GET A FEW ELEVATED SHOWERS TO DEVELOP ALONG THE
ADVANCING THETA-E GRADIENT ALTHOUGH LAPSE RATES ALOFT ARE JUST NOT
THAT SUPPORTIVE OF CONVECTION. IN THE END...FOR CONTINUITY AND
COLLABORATION WITH SURROUNDING OFFICES...DECIDED TO MAINTAIN CHANCE
POPS FOR SHOWERS OVER NW LOWER MICHIGAN OVERNIGHT BUT HAVE TRIMMED
POPS BACK TO 30 PERCENT OR LESS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 352 AM EDT FRI MAY 17 2013
A WARMER AND PROGRESSIVELY MORE MOIST SOUTHEASTERLY FLOW WILL LEAD
TO CHANCES FOR SHOWERS THIS WEEKEND. THERE WILL BE CHANCES FOR
SHOWERS AND EVEN THUNDERSTORMS EARLY NEXT WEEK WHICH WILL BECOME
LIKELY BY THE MIDDLE OF NEXT WEEK...AS A CUTOFF UPPER TROUGH
APPROACHES FROM OUR SOUTHWEST. FINALLY...CONDITIONS MOST LIKELY DRY
OUT BY THURSDAY AS THIS SYSTEM RETREATS TO THE SOUTHEAST. THE MAIN
LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND HOW MUCH IT WILL
WARM UP THIS WEEKEND INTO EARLY NEXT WEEK.
SATURDAY AND SUNDAY...MODELS ARE ONLY IN FAIR AGREEMENT ON THE
TIMING AND AMOUNT OF MOISTURE ADVECTION INTO THE REGION AS THETA-E
RIDGING APPROACHES THE FORECAST AREA BUT WEAKENS AS IT DOES SO. THIS
IS IN RESPONSE TO A DECAYING AREA OF LOW PRESSURE MOVING BY TO THE
NORTHWEST. IT IS STILL UNCERTAIN IF IT WILL MOISTEN UP ENOUGH ACROSS
NORTHERN MICHIGAN TO ACTUALLY RAIN...AS THE MAIN ACTION LOOKS TO
REMAIN TO OUR WEST. SO WILL BACK OFF ON POPS TO SLIGHT AND LOW
CHANCES FOR SHOWERS. HIGHS SATURDAY RANGING FROM THE MIDDLE 60S TO
MIDDLE 70S...WITH THE WARMER 70S TO LOWER 80S ON SUNDAY EXPECTED.
LOWS SATURDAY NIGHT IN THE MIDDLE 40S TO LOWER 50S.
MONDAY THROUGH THURSDAY...SHOWERS AND THUNDERSTORM CHANCES INCREASE
MONDAY THEN BECOME LIKELY MONDAY NIGHT INTO WEDNESDAY AS A CUTOFF
UPPER LEVEL TROUGH AND WARM FRONT APPROACH FROM THE SOUTHWEST.
EXTENDED MODELS THEN VARY ON THE TIMING OF DRYING FROM THE
NORTH...BUT WILL PENCIL THURSDAY IN AS A DRY DAY AS THIS SYSTEM IS
SHOWN TO SLOWLY RETREAT TO OUR SOUTHEAST. REMAINING WARM WITH HIGHS
IN THE 70S TO LOWER 80S MONDAY...FOLLOWED BY A SLOW COOLING TREND
WITH TEMPERATURES ENDING UP IN THE UPPER 50S TO LOWER 60S FOR HIGHS
BY THURSDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 606 AM EDT FRI MAY 17 2013
SOLID VFR CONDITIONS THROUGH THE UPCOMING TAF FORECAST PERIOD...
BUT WITH GRADUALLY LOWERING CIGS THIS AFTERNOON AND TONIGHT. LIGHT
WINDS (UNDER 10 KNOTS) WITH WIND DIRECTIONS LAKE DOMINATED AT THE
TAF SITES.
&&
.MARINE...
ISSUED AT 352 AM EDT FRI MAY 17 2013
LIGHT WINDS/LOW WAVES WILL PREVAIL ON THE LAKES TODAY AND TONIGHT
WITH NO MARINE HEADLINES NEEDED. SOUTH-SOUTHEAST FLOW INCREASES
SATURDAY AND SATURDAY NIGHT AND A HANDFUL OF SMALL CRAFT ADVISORIES
MAY BE NEEDED. AT THAT TIME.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...AS
SHORT TERM...BA
LONG TERM...AS
AVIATION...BA
MARINE...BA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
143 AM EDT FRI MAY 17 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 421 PM EDT THU MAY 16 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW TROFFING ALONG THE W COAST
OF THE CONUS...BROAD RIDGING OVER THE CNTRL CONUS...AND A TROF
EXTENDING S INTO NEW ENGLAND. AHEAD OF THE RIDGE...IT`S BEEN A
GENERALLY SUNNY DAY ACROSS THE FCST AREA. WITH THE DRY AIR NOTED ON
THE 12Z KGRB SOUNDING...DWPTS HAVE FALLEN INTO THE 20S OVER PORTIONS
OF THE INTERIOR W HALF OF UPPER MI...RESULTING IN RH DOWN AROUND
20PCT. SFC HIGH PRES ASSOCIATED WITH APPROACHING MID LEVEL RIDGE IS
SETTLING S OVER THE UPPER GREAT LAKES AND WILL LEAD TO A QUIET NIGHT
TONIGHT. TO THE W...A COUPLE OF SHORTWAVES EMERGING OVER THE WRN
HIGH PLAINS ARE GENERATING SHRA/TSRA FROM ND TO NEBRASKA. THE SRN
WAVE OVER WRN NEBRASKA IS THE STRONGER ONE. HEADING INTO LATER
FRI...FCST WILL REVOLVE AROUND WHAT AFFECTS THESE WAVES WILL HAVE
FOR UPPER MI.
AS ALLUDED TO ABOVE...SFC HIGH PRES WILL LEAD TO A TRANQUIL NIGHT
ACROSS THE FCST AREA. MAINLY CLEAR SKIES WITH PRECIPITABLE WATER
AROUND 50PCT OF NORMAL WILL LEAD TO A QUICK TEMP DROP AFTER SUNSET.
COLUMN MOISTURE BEGINS TO INCREASE OVER THE W OVERNIGHT...AND SOME
OF THAT WILL MANIFEST ITSELF AS HIGH AND MID CLOUDS SPREADING E FROM
THE SHRA AREA CURRENTLY OVER THE DAKOTAS. IN THE END...THIS SHOULD
LEAD TO LOWEST MINS OVER THE E...THOUGH SOME OF THE TRADITIONAL COLD
SPOTS OVER THE W MAY BE EQUALLY AS LOW GIVEN THE GOOD RADIATIONAL
COOLING CONDITIONS EARLY IN THE NIGHT. GENERALLY FAVORED THE LOWER
END OF GUIDANCE ACROSS THE BOARD IN THE INTERIOR. A FEW OF THE
TYPICAL COLD SPOTS MAY SLIP JUST BLO 30F.
WHETHER ANY PCPN MAKES INTO THE FCST AREA FRI IS THE BIG QUESTION.
THE NAM IS VERY AGRESSIVE WITH PCPN...BRINGING OVER AN INCH OF RAIN
TO KIWD BY 00Z SAT WITH PCPN SPREADING AS FAR E AS SENEY. THE GFS
FOLLOWS CLOSE BEHIND THE NAM...THOUGH ITS PCPN FIELD IS DISPLACED A
LITTLE FARTHER S. THE GEM HAS NO PCPN THRU 00Z SAT...THE UKMET ONLY
BRINGS A FEW HUNDREDTHS TO SCNTRL UPPER MI...AND THE 12Z ECMWF IS
SIMILAR WITH A FEW HUNDREDTHS ALONG THE WI BORDER WHICH IS FARTHER S
AND W THAN ITS 00Z RUN. SUSPECT THE STRONGER MORE WELL-DEFINED SRN
WAVE OVER THE WRN PLAINS WILL BE THE BIGGER PLAYER...RESULTING IN
PCPN WITH THE NRN WAVE OVER ND GRADUALLY DRYING UP AS IT WILL HAVE
LIMITED/NO MOISTURE INFLOW AND IT WILL BE ENCOUNTERING DRIER AIR TO
THE E. EVEN PCPN WITH THE SRN WAVE WILL PROBABLY TEND TO DIMINISH OR
AT LEAST BE SLOWER TO ARRIVE DUE TO THE DRIER AIR OVER GREAT
LAKES...ESPECIALLY SINCE LOW-LEVEL TRAJECTORIES HAVE A GOOD EASTERLY
COMPONENT FRI THAT WILL HELP TO MAINTAIN DRY AIR OVER THE AREA. SO
PLAN WILL BE TO FAVOR THE DRIER NON NCEP MODELS FOR FRI. WHILE
RELUCTANT TO ADD PCPN CHC...WILL INCLUDE A SCHC MENTION ALONG THE WI
BORDER SINCE THE THERE WAS ONLY ONE MODEL (GEM) THAT HAD A
COMPLETELY DRY FCST. FOLLOWING THE DRIER SCENARIO...ALSO UTILIZED
LOWER DWPTS FOR FRI BY COMBINING SOME OF THE BIAS CORRECTED GUIDANCE
(GEM IN PARTICULAR) WITH DWPTS CALCULATED BASED ON MIXING HEIGHT.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 421 PM EDT THU MAY 16 2013
CONFIDENCE IS STILL RATHER LOW ON QPF POTENTIAL FRIDAY NIGHT INTO
SATURDAY ASSOCIATED WITH THE DEVELOPING BAROCLINIC ZONE. AS THE
850MB LOW OVER THE CENTRAL AND NORTHERN ROCKIES MOVES EAST...STRONG
WARM ADVECTION AND ISENTROPIC LIFT WILL SPREAD ACROSS THE UPPER
MIDWEST. THE NAM IS VERY AGGRESSIVE IN DEVELOPING SIGNIFICANT
ELEVATED CONVECTION CLOSE TO THE MI/WI BORDER LATE FRI AFTN INTO
FRIDAY NIGHT...WITH OVER 2 INCHES OF QPF FORECAST AT IMT AND IWD BY
SAT AFTN. THE 12Z GFS HAS SHIFTED THE BAROCLINIC AXIS
NORTHWARD...BUT IT IS NOT AS STRONG AS THE NAM. THE 00Z ECMWF IS
OVERALL THE WEAKEST WITH THE FRONTAL BOUNDARY BUT NONETHELESS IS
SIMILAR IN POSITION BUT A LITTLE SLOWER (SIMILAR TO WHAT THE 18Z NAM
SHOWS). THE GEM IS MUCH FURTHER SOUTH. WITH ALL THAT SAID...THE
CONSENSUS OF DETERMINISTIC AND ENSEMBLE NWP SUGGEST THAT POPS WILL
NEED TO BE RAISED ACROSS THE ENTIRE AREA (EXCEPT EAST 1/3) FRIDAY
NIGHT INTO SATURDAY. WITH THE STRONGLY CONFLUENT FLOW AND DRY AIR IN
PLACE...DO NOT EXPECT THE HEAVY PCPN PER THE NAM FORECAST...HOWEVER
SOME SHOWER ACTIVITY FRIDAY NIGHT INTO SATURDAY IS EXPECTED
ESPECIALLY CLOSER TO THE WI BORDER WHERE THE BETTER MOISTURE AND
BETTER LIFT ASSOCIATED WITH THE FRONTAL ZONE IS LOCATED.
BY SATURDAY AFTERNOON...THE BAROCLINIC ZONE SHIFTS NORTH OF THE AREA
WITH THE BEST MOISTURE TRANSPORT CLOSER TO THE LOW TO THE WEST OF
THE AREA. IN FACT...WILL LIKELY SEE SOME CLEARING LATE SAT AFTN AS
THE WARM SECTOR MOVES OVER THE AREA AND DRIER AIR ADVECTS INTO THE
AREA. WILL MAINTAIN LOW CHANCE POPS WEST SAT AFTN/NIGHT...BUT
GENERALLY DRY ELSEWHERE.
SUNDAY SHOULD END UP BEING GENERALLY DRY WITH THE BEST MOISTURE AND
LOW LVL JET TO THE WEST OF THE AREA. NAM AND GFS ARE VERY AGGRESSIVE
IN WARMING 850MB TEMPS TO +18C ACROSS THE SOUTH...BUT AM THINKING
THE MORE CONSERVATIVE ECMWF WITH 850MB TEMPS AROUND +14 SEEMS MORE
REASONABLE. REGARDLESS...SHOULD BE A NICE DAY WITH PERHAPS A CHANCE
OF SHOWERS AND THUNDERSTORMS LATE IN THE DAY SUNDAY ACROSS THE WEST.
RATHER UNSETTLED WEATHER WILL CONTINUE THROUGH THE EARLY PART OF
NEXT WEEK WITH THE UPPER LOW OVER THE NORTHERN PLAINS BEING RATHER
STUBBORN TO MOVE OUT. THIS WILL KEEP THE BAROCLINIC ZONE NEARBY
THROUGH WEDNESDAY BEFORE AN UPPER TROUGH OVER HUDSON BAY DIVES SOUTH
AND ALLOWS THE FRONT TO MOVE SOUTH OF THE AREA BY THURSDAY. WITH
THAT SAID...MON-WED LOOKS QUITE WET AT TIMES WITH SOME HEAVY RAIN
CERTAINLY POSSIBLE. ALTHOUGH 850MB TEMPS WILL BE AROUND +10C THROUGH
WED...EASTERLY FLOW DUE TO THE LOW STAYING SOUTH OF THE AREA AS WELL
AS PLENTIFUL CLOUDS WILL KEEP TEMPS COOL NEAR LAKE SUPERIOR. INLAND
TEMPS WILL LIKELY STAY NEAR NORMAL...BUT TEMPS CLOSER TO LAKE
SUPERIOR WILL BE IN THE UPPER 50S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 142 AM EDT FRI MAY 17 2013
ALTHOUGH HI CLDS WL BE ON THE INCREASE THRU TODAY...EXPECT VFR
CONDITIONS TO PREVAIL THRU THIS FCST PERIOD WITH DRY E WIND OUT OF
HUDSON BAY HI PRES. IF THIS HI RETREATS...SOME -SHRA MAY IMPACT IWD
THIS EVNG. BUT MENTIONED ONLY VCSH ATTM GIVEN LIKELY PERSISTENCE OF
DRY AIR ASSOCIATED WITH STUBBORN HUDSON BAY HI PRES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EDT THU MAY 16 2013
LIGHT WINDS WILL BE THE RULE ACROSS LAKE SUPERIOR TONIGHT WITH HIGH
PRES OVER THE UPPER LAKES. WHILE THE HIGH WILL BE SHIFTING E FRI...A
MESO HIGH MAY LINGER OVER ERN LAKE SUPERIOR THRU THE DAY. THIS WILL
KEEP WINDS LIGHT OVER THE E...BUT E TO NE WINDS WILL BEGIN TO
INCREASE OVER THE W. HEADING THRU THE WEEKEND INTO EARLY NEXT
WEEK...PRES GRADIENT OVER THE UPPER LAKES WILL SLOWLY TIGHTEN BTWN
LOW PRES SLOWLY MOVING FROM THE WRN PLAINS TOWARD THE UPPER
MISSISSIPPI VALLEY AND HIGH PRES BUILDING IN THE VCNTY OF WRN HUDSON
BAY. THIS WILL LEAD TO EASTERLY WINDS GRADUALLY INCREASING INTO
GENERALLY THE 15-25KT RANGE. COULD BE SOME PERIODS OF HIGHER WINDS
AT TIMES EARLY NEXT WEEK...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...MRD
AVIATION...KC
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
900 PM CDT SAT MAY 18 2013
.UPDATE...
00Z AVIATION DISCUSSION ADDED BELOW.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
THE HYDROLOGIC ISSUES FOR TONIGHT AND SUNDAY ARE DISCUSSED IN A
SEPARATE SECTION BELOW. CONVECTION IS EXPECTED TO DEVELOP LATE
THIS AFTERNOON ACROSS WEST CENTRAL MN AND PROPAGATE SLOWLY ENE
THROUGH THE EVENING. MORE CONVECTION IS FORECAST TO EXPLODE OVER
NE/KS AND RACE NE...PERHAPS REACHING SW MN AFTER MIDNIGHT AND INTO
CENTRAL...EAST CENTRAL AND SOUTHEAST MN DURING THE LATE NIGHT
HOURS. DEEP LAYER SHEAR IS BEST TONIGHT ACROSS WEST CENTRAL INTO
CENTRAL MN ALONG WITH ML CAPE NEAR 1500 J/KG. DOWNDRAFT CAPE IS
ALREADY NEAR A 1000 J/KG NEAR OUR WESTERN BORDER ATTM. HENCE...A
FEW SEVERE STORMS WITH HAIL AND WIND ARE POSSIBLE.
SUNDAY SHOULD BEGIN WITH CONVECTION ACROSS CENTRAL AND EASTERN MN
WHICH WILL WEAKEN/DISSIPATE WHILE MOVING NE THROUGH THE LATE
MORNING HOURS. THERE MAY BE A FEW HOURS DURING THE LATE MORNING
AND EARLY AFTERNOON WITH SOME SUNSHINE AND LITTLE CONVECTION
OCCURRING. THAT IS LIKELY TO CHANGE DURING THE MID TO LATE
AFTERNOON HOURS WITH CLUSTERS OF STRONG TO SEVERE STORMS
DEVELOPING ACROSS CENTRAL AND SOUTHERN MN AND BY EVENING ACROSS
WEST CENTRAL WI. MODEL CONSENSUS IS FOR 1500-2000 J/KG OF CAPE
WITH NEARLY 500 J/KG BEING HAIL CAPE. DEEP LAYER SHEAR IS BEST
(30-40 KNOTS) ACROSS SOUTHERN MN INTO WEST CENTRAL WI DURING THE
LATE AFTERNOON AND EVENING. HOWEVER...0-1KM SHEAR INCREASES TO
NEAR 25 KNOTS ACROSS CENTRAL MN WITH SFC-3KM CAPE OVER 150 J/KG
ALONG AND SOUTH OF THE AFOREMENTIONED BOUNDARY. THIS WILL NEED TO
BE WATCHED FOR POSSIBLE TORNADIC DEVELOPMENT.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
THE LONG TERM FORECAST REMAINS QUITE WET INTO THURSDAY AS A
VERTICALLY STACKED LOW PRESSURE SYSTEM OVER THE NORTHERN AND
CENTRAL PLAINS BEGINS A SLOW EASTWARD DRIFT. THUNDERSTORMS WILL
WANE SUNDAY NIGHT WHILE MOVING NE. HOWEVER...MONDAY REMAINS A DAY
OF INTEREST FOR MORE SEVERE WEATHER OVER OUR EASTERN FA. AN
OCCLUDED FRONT WILL LIFT NORTHEAST ACROSS EASTERN MN AND WEST
CENTRAL WI DURING THE DAY. CAPE AND SHEAR VALUES ARE RESPECTABLE
BY AFTERNOON FROM THE TWIN CITIES ON EAST AND SOUTH AND A FEW MORE
SEVERE STORMS ARE POSSIBLE. THERE REMAINS A SMALL CHANCE FOR
THUNDER TUESDAY AND WEDNESDAY...DEPENDING ON HOW FAST THE
VERTICALLY STACKED LOW PRESSURE SYSTEM MOVES. RIGHT NOW...THERE
CONTINUES TO BE A SLOWING TREND. HENCE...WE WILL BE DEALING WITH
RATHER HIGH POPS THROUGH MID WEEK.
THE GFS AND EC SHOW THIS LOW PRESSURE SYSTEM BREAKING DOWN ACROSS
THE REGION ON THURSDAY WITH HIGH PRESSURE FOR FRIDAY AND PERHAPS
SATURDAY BEFORE YET ANOTHER LARGE UPPER TROUGH MOVES INTO THE
WESTERN THIRD OF THE NATION...SPREADING MORE SHOWERS BACK. THE
WARMEST DAY IN THE EXTENDED RANGE IS ON MONDAY WITH HIGHS IN THE
50S AND 60S FOR TUESDAY AND WEDNESDAY WITH 60S TO LOWER 70S FOR
FRIDAY AND SATURDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 859 CDT SAT MAY 18 2013
UNCERTAINTY RULES THE DAY IN THESE TAFS AS A FEW ROUNDS OF SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE. THIS EVENING...STORMS HAVE
INITIATED IN WRN MN ALONG A STATIONARY FRONT THAT STRETCHES EAST
ACROSS CENTRAL MN INTO NW WI. BASED ON MEMBERS 1 AND 3 OF THE
HOPWRF...EXPECT THESE CELLS TO REMAIN CONFINED TO NEAR THEIR
CURRENT LOCATION DUE TO WEAK STEERING FLOW AND SLOWLY DISSIPATE
AFTER SUNSET. ATTENTION THEN TURNS TO LINE OF BKN STORMS FROM
SODAK ALL THE WAY DOWN TO KS AS IT PUSHES EAST OVERNIGHT. TIMED
THIS NEXT BATCH OF SHRA/TSRA IN OFF THE HRRR...THOUGH IT IS
RUNNING A FEW HOURS FASTER THAN THE HOPWRF. NOTICED THE 22Z
VERSION OF THE HRRR SLOWED THE LINE DOWN SOME AS WELL...SO THE
RETURN OF SHRA/TSRA LATE TONIGHT INTO SUN MORNING MAY NEED TO BE
SLOWED DOWN. SUNDAY MORNING MAY VERY WELL BE SIMILAR TO WHAT WAS
SEEN THIS MORNING WITH CONVECTION THAT MOVED ACROSS THE AREA.
EXPECT MAINLY VFR CIGS THROUGH THE NIGHT...THOUGH WITH RECENT RAIN
AND HIGH DEWPS...MVFR VSBYS IN BR/HZ WILL LIKELY DEVELOP. EXPECT
ANOTHER LULL IN ACTIVITY IN THE LATE MORNING/EARLY AFTERNOON
SUNDAY...BEFORE MORE STORMS DEVELOP MAINLY AFTER 20Z ON SUNDAY.
SOUNDINGS AT ALL TERMINALS ARE MOIST/UNSTABLE AND WEAKLY CAPPED...
SO WILL NOT TAKE MUCH FORCING TO KICK OFF STORMS. GIVEN HIGH
CONFIDENCE IN THUNDERSTORMS OCCURRING TOMORROW...BUT LOW
CONFIDENCE IN TIMING/LOCATION THIS FAR OUT...WENT WITH PROB30
GROUPS FOR TSRA AT ALL TERMINALS SUNDAY AFTERNOON.
KMSP...EXPECT ANY TSRA ACTIVITY THIS EVENING TO REMAIN NEAR OR
NORTH OF THE BOUNDARY SITUATED ACROSS CENTRAL MN. CONFIDENCE IS
HIGH IN ANOTHER ROUND OF MORNING STORMS FOR MSP...THOUGH THERE ARE
TIMING ISSUES WITH IT. 21Z RUN OF THE HRRR HAS STORMS APPROACHING
THE FIELD AT 11Z...WHILE ALL MEMBERS OF THE HOPWRF HAVE THE LINE
WELL WEST OF THE FIELD AT 12Z SUNDAY. HAVE A SOMEWHAT LARGE 10Z TO
16Z WINDOW FOR CONVECTION...BUT DOES LOOK LIKE FOR 2 OR 3 OF THOSE
HOURS...THERE WILL BE TSRA ACTIVITY. FOR SUNDAY AFTERNOON/EVENING...
GIVEN UNSTABLE AND WEAKLY CAPPED ENVIRONMENT...EXPECT WIDESPREAD
TSRA TO DEVELOP AGAIN IN THE AFTERNOON AND LAST INTO SUNDAY
EVENING. STILL PLENTY OF UNCERTAINTY WITH TIMING/PLACEMENT OF
STORMS SUNDAY AFTERNOON...SO HAVE A PROB30 GROUP FOR MOST LIKELY
WINDOW FOR SEEING STORMS AT THIS POINT.
/OUTLOOK FOR KMSP/
MON...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S 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 312 PM CDT SAT MAY 18 2013
A SIGNIFICANT RAINFALL EVENT IS POSSIBLE TONIGHT AND SUNDAY
MORNING ACROSS CENTRAL MN. PW VALUES ARE PROJECTED TO INCREASE TO
OVER 1.50 INCHES TONIGHT ACROSS THE MN FA IN CONCERT WITH A
DEVELOPING LOW LEVEL JET. THE PW VALUES FORECAST ARE BETTER THAN
2 STANDARD DEVIATIONS ABOVE NORMAL AND ARE NEAR RECORD VALUES FOR
THE MONTH OF MAY (1.67). A SPECIAL 16Z KMPX RAOB THIS MORNING ALREADY
HAD PW VALUES AT 1.38 INCHES. WITH THE INCREASE IN MOISTURE
TONIGHT... THERE IS STRONG (925-850MB) FRONTOGENESIS THAT DEVELOPS
ACROSS CENTRAL MN AND REMAINS IN PLACE THROUGH MIDDAY SUNDAY. IN
ADDITION...AN INVERTED SURFACE TROUGH ACROSS CENTRAL SD AND
EASTERN ND IS FORECAST TO DROP SE INTO CENTRAL AND NORTHERN MN
BY SUNDAY MORNING WITH PRETTY STRONG LOW LEVEL CONVERGENCE SHOWN.
VARIOUS WRF MODELS SHOW CONVECTION SPREADING/DEVELOPING ACROSS
CENTRAL MN THIS EVENING WITH TRAINING NOTED. ANOTHER ROUND OF
CONVECTION MAY MOVE IN LATE IN THE NIGHT FROM EASTERN SD AND SW
MN. THE STORMS COULD EASILY PRODUCE 1 TO 2 INCHES OF RAIN PER HOUR
AS THEY MOVE THROUGH...MUCH LIKE THE STORMS LAST NIGHT AND THIS
MORNING OVER PARTS OF THE MN FA. IN FACT...WIDESPREAD 1 TO 3 INCH
RAINS FELL ACROSS CENTRAL MN EARLY THIS MORNING...WHICH HAS
CERTAINLY SOAKED THE GROUND. HENCE...IN COLLABORATION WITH
KDLH...WE ISSUED A FLASH FLOOD WATCH FROM 9 PM THIS EVENING UNTIL
1 PM ON SUNDAY FOR AREAS ALONG AND NORTH OF A LINE FROM MORRIS
THROUGH ST. CLOUD TO CAMBRIDGE.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR MNZ041>045-
047>052.
WI...NONE.
&&
$$
SHORT TERM...RAH
LONG TERM...RAH
AVIATION...MPG
HYDROLOGY...RAH
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
927 PM CDT SAT MAY 18 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 CORFEDI 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 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 615 PM CDT SAT MAY 18 2013
EXPECT VFR CONDITIONS WITH OCCASIONAL PERIODS OF MVFR DUE TO
CEILINGS TO DOMINATE SOUTHWESTERN MISSOURI AIRFIELDS FOR THE
DURATION OF THE TAF FORECAST PERIOD. A WARM MOIST SOUTHERLY FLOW
OF AIR STREAMING NORTHWARD FROM THE GULF OF MEXICO WILL KEEP THE
MISSOURI OZARKS UNDER VERY HUMID AND VARIABLY CLOUDY CONDITIONS
INTO SUNDAY AFTERNOON. AN UPPER LEVEL HIGH PRESSURE SYSTEM
CURRENTLY OVER MISSOURI WILL CONTINUE TO SHIFT EASTWARD THROUGH
SUNDAY. THIS WILL BE FOLLOWED BY A SEASONABLY STRONG STORM SYSTEM
THAT WILL BRING STRONG TO SEVERE THUNDERSTORMS TO THE AREA ALONG
WITH PERIODS OF HEAVY RAIN...SHORTLY AFTER THE END OF THIS TAF
FORECAST PERIOD. INCLUDED TWO PERIODS OF LOW LEVEL WIND SHEAR AT
JLN LATER TONIGHT AND EARLY TOMORROW MORNING AS A LOW LEVEL
SOUTHWESTERLY JET BEGINS TO SET UP.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
UPDATE...COLUCCI
SHORT TERM...WISE
LONG TERM...FOSTER
AVIATION...COLUCCI
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
650 PM CDT SAT MAY 18 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 312 PM CDT SAT MAY 18 2013
(TONIGHT)
THE PRIMARY CONCERN TONIGHT IS POTENTIAL THUNDERSTORM DEVELOPMENT
NORTH OF A NW-SE ORIENTED WARM FRONT THAT WILL LIFT ACROSS THE CWA
OVERNIGHT. GIVEN THE UNSTABLE AIRMASS IN PLACE OVER THE REGION
/MUCAPES ON THE ORDER OF 2500-3000J/KG AS PER THE RUC...GFS...AND
LOCAL WRF MODELS FOR TONIGHT/ ADDITIONAL WAA AND A VEERING LLJ COULD
CERTAINLY PROVIDE ENOUGH LIFT TO FIRE SOME STORMS DURING THE LATE
OVERNIGHT AND EARLY MORNING HOURS. THE 4KM WRF-NNM AND HRRR DEVELOP
SCATTERED STORMS TONIGHT NORTH OF THE FRONT...PARTICULARLY THROUGH
THE 09Z-12Z TIME FRAME. THUS...HAVE MAINTAINED TRENDS IN TONIGHT`S
FORECAST...INTRODUCING SCHC POPS AFTER MIDNIGHT WITH A FOCUSED AREA
OF CHC POPS MARCHING NORTHWARD THROUGH THE LATE OVERNIGHT HOURS AND
TOWARD DAYBREAK.
OTHERWISE...ANOTHER WARM NIGHT IS AHEAD FOR THE AREA...WITH LOW
TEMPERATURES EXPECTED TO DROP INTO THE MIDDLE 60S FOR SOUTHWEST
ILLINOIS TO UPPER 60S OVER MID MISSOURI AND FOR THE STL METRO AREA.
JP
.LONG TERM...(SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
ON SUNDAY...WARM FRONT TO LIFT NORTH OF FORECAST AREA BY
MIDDAY...SO JUST HAVE SLIGHT CHANCE POPS DURING THE MORNING
HOURS...THEN BEST CHANCES OF STORMS IN CENTRAL/NORTHEAST MO...WEST
CENTRAL IL DURING THE AFTERNOON HOURS CLOSER TO THE MAIN WEATHER
SYSTEM. THE ACTIVITY RAMPS UP DURING SUNDAY EVENING AND THE
OVERNIGHT HOURS AS A SHORTWAVE ROTATES AROUND THE UPPER SYSTEM
THROUGH THE FORECAST AREA...THOUGH BEST CHANCES REMAIN OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL ON NOSE OF LOW LEVEL JET.
WITH DECENT SHEAR AND INSTABILITY...AS WELL AS LOW LEVEL
MOISTURE...SEVERE STORMS ARE POSSIBLE OVER THIS AREA...WITH THE
MAIN THREAT BEING LARGE HAIL. OTHERWISE...WITH WARM FRONT LIFTING
NORTH OF FORECAST AREA AND 850 TEMPS APPROACHING 20C...WILL SEE
TEMPS WARM UP INTO THE MID TO UPPER 80S. LOWS SUNDAY NIGHT TO
REMAIN MILD...IN THE MID TO UPPER 60S.
ON MONDAY...ACTIVITY TO TAPER OFF A BIT...BEFORE RAMPING BACK UP
LATE MONDAY AFTERNOON AND THROUGH THE OVERNIGHT HOURS WITH NEXT
SIGNIFICANT SHORTWAVE AND ANOTHER ROUND OF SEVERE WEATHER POSSIBLE.
WITH MODELS CONTINUING TO SLOW DOWN THIS SYSTEM...WILL SEE THE
STORMS PERSIST THROUGH WEDNESDAY BEFORE TAPERING OFF AS FRONTAL
BOUNDARY FINALLY MOVES THROUGH. TEMPERATURES TO REMAIN ABOVE NORMAL
THROUGH THE FIRST PART OF THE WORK WEEK...BEFORE COOLING OFF TO NEAR
NORMAL TEMPS IN THE 70S FOR THE LAST HALF OF THE WORK WEEK.
WITH SLOW EXIT OF SYSTEM AND FRONTAL BOUNDARY STALLED OUT JUST SOUTH
OF FORECAST AREA ON THURSDAY...CHANCE POPS OVER SOUTHEAST HALF OF
FORECAST AREA STILL LOOKS GOOD. OTHERWISE...DRY WEATHER EXPECTED
FRIDAY AND SATURDAY.
BYRD
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 639 PM CDT SAT MAY 18 2013
VFR CONDITIONS ARE EXPECTED FOR AT LEAST THE NEXT FEW HOURS WITH
INCREASING UNCERTAINTY AFTER 06Z. AN AREA OF SHOWERS AND
THUNDERSTORMS IS EXPECTED TO DEVELOP OVER PARTS OF MO/IL OVERNIGHT
DUE TO A WARM FRONT LIFTING THROUGH THE AREA IN THE PRESENCE OF AN
UNSTABLE AIR MASS. VCSH LOOKS REASONABLE ATTM DUE TO UNCERTAINTY
REGARDING COVERAGE AND TIMING. SOUTHEASTERLY WINDS WILL BECOME
SOUTHERLY TOMORROW AND GUST TO AROUND 20-25 KTS ON THE WARM SIDE
OF THE FRONT. SCT SHOWERS AND THUNDERSTORMS ARE POSSIBLE NEAR PEAK
HEATING TOMORROW AFTN /ESPECIALLY ALONG ANY OUTFLOW BOUNDARIES
LEFT OVER FROM EARLIER CONVECTION/.
SPECIFICS FOR KSTL...VFR CONDITIONS ARE EXPECTED FOR AT LEAST THE
NEXT FEW HOURS FOLLOWED BY INCREASING UNCERTAINTY AFTER 06Z. AN
AREA OF SHOWERS AND THUNDERSTORMS IS EXPECTED TO DEVELOP OVER
PARTS OF MISSOURI OVERNIGHT DUE TO A WARM FRONT LIFTING THROUGH
THE AREA IN THE PRESENCE OF AN UNSTABLE AIR MASS. THE COVERAGE AND
SOUTHERN EXTENT OF THE OVERNIGHT CONVECTION ARE UNCERTAIN AT THIS
TIME HOWEVER THE VCSH TIMING IN THE PREVIOUS TAF LOOKS REASONABLE.
SOUTHEASTERLY WINDS WILL BECOME SOUTHERLY AND GUST TO AROUND 20
KTS TOMORROW ON THE WARM SIDE OF THE FRONT. SCT SHOWERS AND
THUNDERSTORMS ARE POSSIBLE NEAR PEAK HEATING TOMORROW
AFTERNOON /ESPECIALLY ALONG ANY OUTFLOW BOUNDARIES LEFT OVER FROM
EARLIER CONVECTION/ BUT THE BEST CHC FOR PCPN WILL BE AFTER THE
END OF THE VALID TAF PD.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1252 PM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 313 AM CDT FRI MAY 17 2013
THE MAIN FEATURE OF INTEREST TODAY IS THE UPPER LOW WHICH PROFILER
AND WATER VAPOR SUGGEST IS CURRENTLY LOCATED ACROSS EXTREME SRN MO
NEAR WEST PLAINS. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT
TRACKING THE LOW E/NEWD TODAY WITH THE MORE SRN POSITION OF THE
LOCAL WRF AND RUC PREFERRED. THIS TRACK WOULD TAKE THE LOW ACROSS
THE EASTERN OZARKS THIS MORNING AND INTO SRN IL THIS AFTENOON. THE
BIGGEST UNCERTAINTY WITH THIS SYSTEM IS THE N/NW EXTENT OF
PRECIPITATION AND COVERAGE. CLOUD TOPS HAVE BEEN COOLING THE LAST
FEW HOURS IS ASSOCIATION WITH AN INCREASING AMOUNT OF SHOWERS. THE
EXPLICIT GUIDANCE GENERALLY DEPICTS SCATTERED COVERAGE
DIMINISHING WITH NORTHWARD EXTENT. THIS SEEMS REASONABLE AND HAS
BEEN GENERALLY ACCEPTED WITH THE HIGHEST POPS ACROSS SE MO INTO
SRN IL. THE THREAT OF CONVECTION SHOULD INCREASE LATER THIS
MORNING IS ASSOCIATION WITH HEATING AND DESTABILIZATION. THE UPPER
LOW SHOULD BE IN SRN IL BY EARLY EVENING...DEPARTING TO THE EAST
NORTHEAST. ANY PRECIPITATION IN THE WAKE OF THE LOW SHOULD BE
STRONGLY TIED TO HEATING...DISSIPATING DURING THE EVENING.
GLASS
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 313 AM CDT FRI MAY 17 2013
SATURDAY LOOKS LARGELY DRY AS A RIDGE ALOFT BUILDS INTO THE AREA
IN ASSOCIATION WITH OVERALL UPSTREAM AMPLIFICATION. LOW LEVEL WAA
WILL INCREASE AND THIS COMBINED WITH LESS CLOUD COVER WILL RESULT
IN WARMER TEMPERATURES. THE CHANCE OF SHOWERS AND THUNDERSTORMS
WILL RE-ENTER THE PICTURE ON SAT NIGHT IN RESPONSE TO LOW LEVEL
WAA/MCON VIA A SWLY LLJ...BRINGING THE POTENTIAL FOR ELEVATED
ACTIVITY TO THE NORTH OF A SLOWLY LIFTING WARM FRONT. THE HIGHEST
PROBABILIT AT THIS TIME APPEARS TO BE ACROSS NRN MO INT CENTRAL
IL. THERE COULD BE ONGOING/RESIDUAL ELEVATED ACTIVITY NORTH OF THE
WARM FRONT ACROSS NE MO/WEST CENTRAL IL ON SUNDAY MORNING.
OTHERWISE INCREASING SOUTHERLY FLOW AND WAA SHOULD RESULT IN
CONTINUED WARMER TEMPERATURES WITH SOME LOCATIONS PUSHING 90
DEGREES.
A VERY ACTIVE PERIOD WILL BEGIN TO UNFOLD LATE SUNDAY AFTERNOON
AND CONTINUE THROUGH AT LEAST TUESDAY NIGHT AS RATHER DEEP AND
BROAD UPPER TROF/UPPER LOW MOVES SLOWLY EAST AND A SERIES OF SHORT
WAVES EJECT E/NEWD. A MOIST AND VERY UNSTABLE AIR MASS WILL BE IN
PLACE AND THIS COMBINED WITH FAVORABLE DEEP LAYER SHEAR WILL
SUPPORT MULTIPLE SEVERE WEATHER EPISODES OVER A 3 DAY PERIOD
MIGRATING WEST TO EAST ACROSS THE CWA WITH THE MOST ACTIVE PERIOD
FROM MONDAY THROUGH TUESDAY NIGHT.
GLASS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1233 PM CDT FRI MAY 17 2013
A LOW PRESSURE SYSTEM CONTINUES TO SLOWLY SPIN EASTWARD ACROSS
SOUTHERN MO AND INTO THE OHIO VALLEY...WITH ASSOCIATED
PRECIPITATION CONTINUING TO PERCOLATE NORTHWARD OVER EASTERN MO
AND SOUTHERN AND SOUTHWEST IL. HAVE GONE WITH MENTION OF VCSH FOR
METRO TAF SITES THROUGH THIS EVENING...AS IT APPEARS THAT THE MAIN
FOCUS FOR TSRA SHOULD REMAIN WELL SOUTHEAST OF THE TERMINALS. LOSS
OF HEATING AFTER SUNSET SHOULD ACT TO STYMIE ANY ADDITIONAL
DEVELOPMENT IN OUR AREA. CONDITIONS ARE EXPECTED TO REMAIN LOW-END
VFR...THOUGH MVFR CONDITIONS COULD ACCOMPANY SOME OF THE SHOWERS.
FOR TONIGHT THROUGH SATURDAY MORNING...HAVE MAINTAINED TAF TRENDS
FROM THE PREVIOUS ISSUANCE FOR THE DEVELOPMENT OF FOG ACROSS MUCH
OF THE REGION. GIVEN AMPLE MOISTURE AND LIGHT/VAR WINDS EXPECTED
OVERNIGHT...EXPECT MVFR DECREASING TO IFR FOG TO IMPACT KSTL AND
KSUS...WITH VLIFR POSSIBLE FOR KCOU. THERE MAY ALSO BE SOME FOG
DEVELOPMENT FOR A FEW HOURS PRIOR TO DAYBREAK AT KUIN...THOUGH DO
NOT EXPECT CONDITIONS TO DROP BELOW MVFR AT THIS TIME. GRADUAL
IMPROVEMENT WILL OCCUR SATURDAY MORNING...WITH CIGS BECOMING SCT
VFR AS A RIDGE BUILDS INTO EASTERN MO.
SPECIFICS FOR KSTL...
SHOWERS CONTINUE TO PERCOLATE ACROSS EASTERN MO THIS AFTERNOON DUE
TO A SLOW MOVING LOW PRESSURE SYSTEM...THROUGH ARE EXPECTED TO
TAPER OFF AFTER SUNSET WITH A LOSS OF DAYTIME HEATING. WHILE A
RUMBLE OF THUNDER CANNOT BE RULED OUT...FEEL THAT THE FOCUS FOR
THUNDERSTORM ACTIVITY REMAINS WELL SOUTHEAST OF THE TERMINAL...AND
THUS HAVE CONTINUED MENTION OF VCSH. LOW-END VFR CONDITIONS WILL
PREVAIL TODAY...POSSIBLY MVFR AS SHOWERS MOVE THROUGH THE
AREA...THOUGH WILL GENERALLY BE ON THE CUSP BETWEEN MVFR AND VFR
UNTIL LATE TONIGHT. AMPLE MOISTURE AND LIGHT/VAR WINDS OVERNIGHT
WILL RESULT IN MVFR FOG DEVELOPMENT AOA 04Z...DECREASING TO IFR
AFTER 07Z...WITH LITTLE IMPROVEMENT EXPECTED UNTIL AFTER SUNRISE
SATURDAY MORNING. OTHERWISE...SATURDAY IS EXPECTED TO BE
DRY...WITH CIGS BECOMING SCT VFR BY LATE MORNING/EARLY AFTERNOON.
JP
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1229 PM CDT Fri May 17 2013
.SHORT TERM...(Today through Saturday night)
Issued at 403 AM CDT FRI MAY 17 2013
Closed upper low over extreme north central AR will continue an
eastward track and move away from the CWA today. Could see an
isolated shower or storm over the far eastern counties later this
morning and early afternoon as any remaining vorticity lobes rotate
cyclonically westward. Stratus has formed over the southern CWA.
These clouds on the northwest side of the upper low an increasingly
moist boundary layer. 06z RAP has best handle on the current low
cloud trends and followed. Airmass over the CWA is very similar to
yesterday. However, except for the far northwest corner of MO believe
max temperatures today may be a few degrees cooler than yesterday due
to increased cloud cover.
The earlier upstream convection over KS and NE was tied to a couple
of weak vorticity lobes. Convection has all but dissipated and dont`
expect it to reform today.
Shortwave ridging aloft is progged to amplify as it moves east
across the Central and Southern Plains this afternoon through
Saturday. This should yield dry and warmer conditions on Saturday.
Expect max temperatures in the middle to upper 80s.
Saturday night is looking a tad more interesting as it no longer
looks dry. NAM/GFS/ECMWF/GEM have been giving signals for the past
couple of runs that elevated convection will form Saturday evening
over eastern KS/western MO and quickly advance northeast Saturday
night. With a stout elevated mixed layer providing an impediment to
surface based convection, any activity will need to rely on
isentropic ascent and a ramping up of the h8 low level jet.....and
we have that. So, have no qualms in adding at least slight chance
PoPs for Saturday night to most of the CWA. Even went with chance
PoPs over the northeastern CWA as the initial activity will have had
time to increase in coverage as it moves quickly northeast.
.LONG TERM...(Sunday through Thursday)
Issued at 403 AM CDT FRI MAY 17 2013
For Sunday, there remains a good chance for severe weather from the
afternoon into the overnight hours. A trough is expected to move
into the Plains by Sunday afternoon leading to a surface low that
will move to our north. This will result in the entire area being in
a broad warm sector with dewpoints likely in the mid to upper 60s.
Model soundings show a strong CAP over the region but also with the
potential for elevated showers/storms earlier in the day. This
possible area of precipitation should move east into the Mississippi
Valley by the afternoon leaving eastern Kansas and western Missouri
to see better destabilization during the afternoon. CAPE values in
the 2500 to 3500 J/kg range look likely given forecast dewpoints so
we will see moderate to strong instability build across our western
zones. The finer scale details of what impact the convection earlier
in day will have will only be able to be resolved during the nowcast
period. But strong instability and 0-6KM shear in the 40 to 50 kt
range, oriented more normal to any initiating boundary, indicates
supercells would be the most likely convective mode initially.
Hodographs show a good amount of curvature by the afternoon and this
is increased during the evening as the low level jet restrengthens
overhead. Storms will likely initiate over eastern Kansas during the
afternoon hours and become supercells. As winds veer into the
evening and overnight hours storms should organize into more of a
line/ convective complex. Large hail, damaging winds and a few
tornadoes are possible with the initial storms before the convective
mode changes and damaging winds becomes the primary concern.
Monday will be greatly dependent upon what happens Sunday night, and
as such confidence is quite a bit lower. Latest guidance suggest
that the front will be nearly east of us by the evening hours with
winds across the area veered southwesterly. Shear and instability
are still supportive of severe weather, but the chances should be
either across our eastern to southern zones or even east of the
forecast area. We will really need to see how the weather pans out
Sunday before a saying anything with any level of certainty.
For the remainder of the extended forecast, the upper trough that
affected the area Sunday and Monday should have cutoff over the
Upper Midwest. Another segment of the upper trough will move through
Wednesday and as a result there may be a few showers or storms
across northern Missouri into central and eastern Missouri. A few
showers and storm will remain a possibility into Thursday as
northern portions of the forecast are still under the influence of
the Upper Midwest upper low. The effects of the upper low will
diminish by Friday as upper ridging spreads into the Plains. This
will result in a warm up with drier conditions more likely for the
weekend. The severe potential looks rather low for this stretch of
time.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1228 PM CDT FRI MAY 17 2013
Widespread MVFR cigs are gradually lifting and scattering, and expect
cumulus field to lift into VFR across the entire region by late
afternoon. Most guidance is suggesting the possibility of IFR
cigs/vsbys redeveloping a bit further north and east late tonight,
possibly affecting the KC terminals and parts of ern KS/wrn MO.
Confidence on this is not high, and increased SE flow should prevent
widespread vsby restrictions, but probabilities for IFR cigs are high
enough for now to introduce this into the TAFs right around sunrise.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...MJ
LONG TERM...CDB
AVIATION...Hawblitzel
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
641 AM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 313 AM CDT FRI MAY 17 2013
THE MAIN FEATURE OF INTEREST TODAY IS THE UPPER LOW WHICH PROFILER
AND WATER VAPOR SUGGEST IS CURRENTLY LOCATED ACROSS EXTREME SRN MO
NEAR WEST PLAINS. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT
TRACKING THE LOW E/NEWD TODAY WITH THE MORE SRN POSITION OF THE
LOCAL WRF AND RUC PREFERRED. THIS TRACK WOULD TAKE THE LOW ACROSS
THE EASTERN OZARKS THIS MORNING AND INTO SRN IL THIS AFTENOON. THE
BIGGEST UNCERTAINTY WITH THIS SYSTEM IS THE N/NW EXTENT OF
PRECIPITATION AND COVERAGE. CLOUD TOPS HAVE BEEN COOLING THE LAST
FEW HOURS IS ASSOCIATION WITH AN INCREASING AMOUNT OF SHOWERS. THE
EXPLICIT GUIDANCE GENERALLY DEPICTS SCATTERED COVERAGE
DIMINISHING WITH NORTHWARD EXTENT. THIS SEEMS REASONABLE AND HAS
BEEN GENERALLY ACCEPTED WITH THE HIGHEST POPS ACROSS SE MO INTO
SRN IL. THE THREAT OF CONVECTION SHOULD INCREASE LATER THIS
MORNING IS ASSOCIATION WITH HEATING AND DESTABILIZATION. THE UPPER
LOW SHOULD BE IN SRN IL BY EARLY EVENING...DEPARTING TO THE EAST
NORTHEAST. ANY PRECIPITATION IN THE WAKE OF THE LOW SHOULD BE
STRONGLY TIED TO HEATING...DISSIPATING DURING THE EVENING.
GLASS
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 313 AM CDT FRI MAY 17 2013
SATURDAY LOOKS LARGELY DRY AS A RIDGE ALOFT BUILDS INTO THE AREA
IN ASSOCIATION WITH OVERALL UPSTREAM AMPLIFICATION. LOW LEVEL WAA
WILL INCREASE AND THIS COMBINED WITH LESS CLOUD COVER WILL RESULT
IN WARMER TEMPERATURES. THE CHANCE OF SHOWERS AND THUNDERSTORMS
WILL RE-ENTER THE PICTURE ON SAT NIGHT IN RESPONSE TO LOW LEVEL
WAA/MCON VIA A SWLY LLJ...BRINGING THE POTENTIAL FOR ELEVATED
ACTIVITY TO THE NORTH OF A SLOWLY LIFTING WARM FRONT. THE HIGHEST
PROBABILIT AT THIS TIME APPEARS TO BE ACROSS NRN MO INT CENTRAL
IL. THERE COULD BE ONGOING/RESIDUAL ELEVATED ACTIVITY NORTH OF THE
WARM FRONT ACROSS NE MO/WEST CENTRAL IL ON SUNDAY MORNING.
OTHERWISE INCREASING SOUTHERLY FLOW AND WAA SHOULD RESULT IN
CONTINUED WARMER TEMPERATURES WITH SOME LOCATIONS PUSHING 90
DEGREES.
A VERY ACTIVE PERIOD WILL BEGIN TO UNFOLD LATE SUNDAY AFTERNOON
AND CONTINUE THROUGH AT LEAST TUESDAY NIGHT AS RATHER DEEP AND
BROAD UPPER TROF/UPPER LOW MOVES SLOWLY EAST AND A SERIES OF SHORT
WAVES EJECT E/NEWD. A MOIST AND VERY UNSTABLE AIR MASS WILL BE IN
PLACE AND THIS COMBINED WITH FAVORABLE DEEP LAYER SHEAR WILL
SUPPORT MULTIPLE SEVERE WEATHER EPISODES OVER A 3 DAY PERIOD
MIGRATING WEST TO EAST ACROSS THE CWA WITH THE MOST ACTIVE PERIOD
FROM MONDAY THROUGH TUESDAY NIGHT.
GLASS
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 621 AM CDT FRI MAY 17 2013
FEW CHANGES WERE MADE TO PREV FORECAST WHICH APPEARS TO BE ON
TRACK. EXPECT CHANCE OF PRECIP TO INCREASE LATE THIS MORNING AND
INTO MID AFTERNOON...MAINLY FOR SUS/CPS. WINDS WILL BE SELY AND
AOB 6 KTS. EXPECT FG/ST TO DEVELOP TONIGHT WITH AMPLE MOISTURE
AND WEAK FLOW. ATTM...EXPECT WORST CONDITIONS AT COU AND
SUS/CPS.
SPECIFICS FOR KSTL...EXPECT MVFR CLOUDS TO AFFECT TERMINAL LATER
THIS MORNING AND INTO THE AFTERNOON. PRECIP CHANCES WILL INCREASE
THRU THE MORNING WITH BEST CHANCES EARLY THIS AFTERNOON. WINDS ARE
EXPECTED TO REMAIN SELY AOB 6 KTS.
TILLY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
632 AM CDT Fri May 17 2013
.SHORT TERM...(Today through Saturday night)
Issued at 403 AM CDT FRI MAY 17 2013
Closed upper low over extreme north central AR will continue an
eastward track and move away from the CWA today. Could see an
isolated shower or storm over the far eastern counties later this
morning and early afternoon as any remaining vorticity lobes rotate
cyclonically westward. Stratus has formed over the southern CWA.
These clouds on the northwest side of the upper low an increasingly
moist boundary layer. 06z RAP has best handle on the current low
cloud trends and followed. Airmass over the CWA is very similar to
yesterday. However, except for the far northwest corner of MO believe
max temperatures today may be a few degrees cooler than yesterday due
to increased cloud cover.
The earlier upstream convection over KS and NE was tied to a couple
of weak vorticity lobes. Convection has all but dissipated and dont`
expect it to reform today.
Shortwave ridging aloft is progged to amplify as it moves east
across the Central and Southern Plains this afternoon through
Saturday. This should yield dry and warmer conditions on Saturday.
Expect max temperatures in the middle to upper 80s.
Saturday night is looking a tad more interesting as it no longer
looks dry. NAM/GFS/ECMWF/GEM have been giving signals for the past
couple of runs that elevated convection will form Saturday evening
over eastern KS/western MO and quickly advance northeast Saturday
night. With a stout elevated mixed layer providing an impediment to
surface based convection, any activity will need to rely on
isentropic ascent and a ramping up of the h8 low level jet.....and
we have that. So, have no qualms in adding at least slight chance
PoPs for Saturday night to most of the CWA. Even went with chance
PoPs over the northeastern CWA as the initial activity will have had
time to increase in coverage as it moves quickly northeast.
.LONG TERM...(Sunday through Thursday)
Issued at 403 AM CDT FRI MAY 17 2013
For Sunday, there remains a good chance for severe weather from the
afternoon into the overnight hours. A trough is expected to move
into the Plains by Sunday afternoon leading to a surface low that
will move to our north. This will result in the entire area being in
a broad warm sector with dewpoints likely in the mid to upper 60s.
Model soundings show a strong CAP over the region but also with the
potential for elevated showers/storms earlier in the day. This
possible area of precipitation should move east into the Mississippi
Valley by the afternoon leaving eastern Kansas and western Missouri
to see better destabilization during the afternoon. CAPE values in
the 2500 to 3500 J/kg range look likely given forecast dewpoints so
we will see moderate to strong instability build across our western
zones. The finer scale details of what impact the convection earlier
in day will have will only be able to be resolved during the nowcast
period. But strong instability and 0-6KM shear in the 40 to 50 kt
range, oriented more normal to any initiating boundary, indicates
supercells would be the most likely convective mode initially.
Hodographs show a good amount of curvature by the afternoon and this
is increased during the evening as the low level jet restrengthens
overhead. Storms will likely initiate over eastern Kansas during the
afternoon hours and become supercells. As winds veer into the
evening and overnight hours storms should organize into more of a
line/ convective complex. Large hail, damaging winds and a few
tornadoes are possible with the initial storms before the convective
mode changes and damaging winds becomes the primary concern.
Monday will be greatly dependent upon what happens Sunday night, and
as such confidence is quite a bit lower. Latest guidance suggest
that the front will be nearly east of us by the evening hours with
winds across the area veered southwesterly. Shear and instability
are still supportive of severe weather, but the chances should be
either across our eastern to southern zones or even east of the
forecast area. We will really need to see how the weather pans out
Sunday before a saying anything with any level of certainty.
For the remainder of the extended forecast, the upper trough that
affected the area Sunday and Monday should have cutoff over the
Upper Midwest. Another segment of the upper trough will move through
Wednesday and as a result there may be a few showers or storms
across northern Missouri into central and eastern Missouri. A few
showers and storm will remain a possibility into Thursday as
northern portions of the forecast are still under the influence of
the Upper Midwest upper low. The effects of the upper low will
diminish by Friday as upper ridging spreads into the Plains. This
will result in a warm up with drier conditions more likely for the
weekend. The severe potential looks rather low for this stretch of
time.
&&
.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 625 AM CDT FRI MAY 17 2013
Latest satellite imagery shows IFR/MVFR stratus is advecting rapidly north
into west central MO/east central KS. Latest 09z RAP output has best
handle on the low clouds and suggests low clouds will be around
into late morning. A light southeast wind maintaining moisture within the
boundary layer and minimal mixing until late this morning supports
this forecast. Areas of MVFR fog will also accompany this cloudiness
for the first few hours of the forecast. Should see clouds scatter
out no later than noon with VFR conditions until the pre-dawn hours
of Saturday morning when conditions favor MVFR fog developing.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...MJ
LONG TERM...CDB
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
404 AM CDT Fri May 17 2013
.SHORT TERM...(Today through Saturday night)
Issued at 403 AM CDT FRI MAY 17 2013
Closed upper low over south central MO will continue an eastward
track and move away from the CWA today. Could see an isolated shower
or storm over the far eastern counties later this morning and early
afternoon as any remaining vorticity lobes rotate cyclonically
westward. Stratus has formed over the southern CWA. These clouds on
the northwest side of the upper low an increasingly moist boundary
layer. 06z RAP has best handle on the current low cloud trends and
followed. Airmass over the CWA is very similar to yesterday. However,
except for the far northwest corner of MO believe max temperatures
today may be a few degrees cooler than yesterday due to increased
cloud cover.
The earlier upstream convection over KS and NE was tied to a couple
of weak vorticity lobes. Convection has all but dissipated and dont`
expect it to reform today.
Shortwave ridging aloft is progged to amplify as it moves east
across the Central and Southern Plains this afternoon through
Saturday. This should yield dry and warmer conditions on Saturday.
Expect max temperatures in the middle to upper 80s.
Saturday night is looking a tad more interesting as it no longer
looks dry. NAM/GFS/ECMWF/GEM have been giving signals for the past
couple of runs that elevated convection will form Saturday evening
over eastern KS/western MO and quickly advance northeast Saturday
night. With a stout elevated mixed layer providing an impediment to
surface based convection, any activity will need to rely on
isentropic ascent and a ramping up of the h8 low level jet.....and
we have that. So, have no qualms in adding at least slight chance
PoPs for Saturday night to most of the CWA. Even went with chance
PoPs over the northeastern CWA as the initial activity will have had
time to increase in coverage as it moves quickly northeast.
.LONG TERM...(Sunday through Thursday)
Issued at 403 AM CDT FRI MAY 17 2013
For Sunday, there remains a good chance for severe weather from the
afternoon into the overnight hours. A trough is expected to move
into the Plains by Sunday afternoon leading to a surface low that
will move to our north. This will result in the entire area being in
a broad warm sector with dewpoints likely in the mid to upper 60s.
Model soundings show a strong CAP over the region but also with the
potential for elevated showers/storms earlier in the day. This
possible area of precipitation should move east into the Mississippi
Valley by the afternoon leaving eastern Kansas and western Missouri
to see better destabilization during the afternoon. CAPE values in
the 2500 to 3500 J/kg range look likely given forecast dewpoints so
we will see moderate to strong instability build across our western
zones. The finer scale details of what impact the convection earlier
in day will have will only be able to be resolved during the nowcast
period. But strong instability and 0-6KM shear in the 40 to 50 kt
range, oriented more normal to any initiating boundary, indicates
supercells would be the most likely convective mode initially.
Hodographs show a good amount of curvature by the afternoon and this
is increased during the evening as the low level jet restrengthens
overhead. Storms will likely initiate over eastern Kansas during the
afternoon hours and become supercells. As winds veer into the
evening and overnight hours storms should organize into more of a
line/ convective complex. Large hail, damaging winds and a few
tornadoes are possible with the initial storms before the convective
mode changes and damaging winds becomes the primary concern.
Monday will be greatly dependent upon what happens Sunday night, and
as such confidence is quite a bit lower. Latest guidance suggest
that the front will be nearly east of us by the evening hours with
winds across the area veered southwesterly. Shear and instability
are still supportive of severe weather, but the chances should be
either across our eastern to southern zones or even east of the
forecast area. We will really need to see how the weather pans out
Sunday before a saying anything with any level of certainty.
For the remainder of the extended forecast, the upper trough that
affected the area Sunday and Monday should have cutoff over the
Upper Midwest. Another segment of the upper trough will move through
Wednesday and as a result there may be a few showers or storms
across northern Missouri into central and eastern Missouri. A few
showers and storm will remain a possibility into Thursday as
northern portions of the forecast are still under the influence of
the Upper Midwest upper low. The effects of the upper low will
diminish by Friday as upper ridging spreads into the Plains. This
will result in a warm up with drier conditions more likely for the
weekend. The severe potential looks rather low for this stretch of
time.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1048 PM CDT THU MAY 16 2013
Only issues for the terminals over the next 24 hours will be this
morning as nearly clear skies might allow for the development of
light fog in the morning. However, confidence is low owing to the
amount of dry air in place across the region.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...MJ
LONG TERM...CDB
AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
345 AM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 313 AM CDT FRI MAY 17 2013
THE MAIN FEATURE OF INTEREST TODAY IS THE UPPER LOW WHICH PROFILER
AND WATER VAPOR SUGGEST IS CURRENTLY LOCATED ACROSS EXTREME SRN MO
NEAR WEST PLAINS. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT
TRACKING THE LOW E/NEWD TODAY WITH THE MORE SRN POSITION OF THE
LOCAL WRF AND RUC PREFERRED. THIS TRACK WOULD TAKE THE LOW ACROSS
THE EASTERN OZARKS THIS MORNING AND INTO SRN IL THIS AFTENOON. THE
BIGGEST UNCERTAINTY WITH THIS SYSTEM IS THE N/NW EXTENT OF
PRECIPITATION AND COVERAGE. CLOUD TOPS HAVE BEEN COOLING THE LAST
FEW HOURS IS ASSOCIATION WITH AN INCREASING AMOUNT OF SHOWERS. THE
EXPLICIT GUIDANCE GENERALLY DEPICTS SCATTERED COVERAGE
DIMINISHING WITH NORTHWARD EXTENT. THIS SEEMS REASONABLE AND HAS
BEEN GENERALLY ACCEPTED WITH THE HIGHEST POPS ACROSS SE MO INTO
SRN IL. THE THREAT OF CONVECTION SHOULD INCREASE LATER THIS
MORNING IS ASSOCIATION WITH HEATING AND DESTABILIZATION. THE UPPER
LOW SHOULD BE IN SRN IL BY EARLY EVENING...DEPARTING TO THE EAST
NORTHEAST. ANY PRECIPITATION IN THE WAKE OF THE LOW SHOULD BE
STRONGLY TIED TO HEATING...DISSIPATING DURING THE EVENING.
GLASS
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 313 AM CDT FRI MAY 17 2013
SATURDAY LOOKS LARGELY DRY AS A RIDGE ALOFT BUILDS INTO THE AREA
IN ASSOCIATION WITH OVERALL UPSTREAM AMPLIFICATION. LOW LEVEL WAA
WILL INCREASE AND THIS COMBINED WITH LESS CLOUD COVER WILL RESULT
IN WARMER TEMPERATURES. THE CHANCE OF SHOWERS AND THUNDERSTORMS
WILL RE-ENTER THE PICTURE ON SAT NIGHT IN RESPONSE TO LOW LEVEL
WAA/MCON VIA A SWLY LLJ...BRINGING THE POTENTIAL FOR ELEVATED
ACTIVITY TO THE NORTH OF A SLOWLY LIFTING WARM FRONT. THE HIGHEST
PROBABILIT AT THIS TIME APPEARS TO BE ACROSS NRN MO INT CENTRAL
IL. THERE COULD BE ONGOING/RESIDUAL ELEVATED ACTIVITY NORTH OF THE
WARM FRONT ACROSS NE MO/WEST CENTRAL IL ON SUNDAY MORNING.
OTHERWISE INCREASING SOUTHERLY FLOW AND WAA SHOULD RESULT IN
CONTINUED WARMER TEMPERATURES WITH SOME LOCATIONS PUSHING 90
DEGREES.
A VERY ACTIVE PERIOD WILL BEGIN TO UNFOLD LATE SUNDAY AFTERNOON
AND CONTINUE THROUGH AT LEAST TUESDAY NIGHT AS RATHER DEEP AND
BROAD UPPER TROF/UPPER LOW MOVES SLOWLY EAST AND A SERIES OF SHORT
WAVES EJECT E/NEWD. A MOIST AND VERY UNSTABLE AIR MASS WILL BE IN
PLACE AND THIS COMBINED WITH FAVORABLE DEEP LAYER SHEAR WILL
SUPPORT MULTIPLE SEVERE WEATHER EPISODES OVER A 3 DAY PERIOD
MIGRATING WEST TO EAST ACROSS THE CWA WITH THE MOST ACTIVE PERIOD
FROM MONDAY THROUGH TUESDAY NIGHT.
GLASS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1158 PM CDT THU MAY 16 2013
LO CIGS ASSOCIATED WITH MORE OF THE CORE OF THE UPPER LEVEL
SYSTEM TO OUR SW WILL EDGE CLOSER TO CNTRL MO AND STL METRO LATE
TONIGHT AND THEN GET SHUNTED OFF TO THE E...AUGMENTED ON FRIDAY BY
DIURNAL INFLUENCES...WITH CLEARING EXPECTED HEADING INTO FRIDAY
EVENING...FOR A TIME. MAY TRIP IFR CIGS AT KCOU AND STL METRO
SITES LATE TONIGHT AND EARLY FRIDAY MORNING BUT STILL THINK IFR
SHOULD STAY TO THE S. A BETTER LO STRATUS AND FOG SETUP APPEARS
TO EXIST ON FRIDAY NIGHT...ESPECIALLY FOR STL METRO SITES...AS
MOISTURE NEVER REALLY GETS SCOURED OUT BEHIND SYSTEM AND WITH SOME
CLEARING EXPECTED AND LIGHT WINDS. ANOTHER ROUND OF SCT TSRA
APPEARS IN THE OFFING FRIDAY AFTERNOON AS UPPER LEVEL SYSTEM WILL
STILL BE CLOSE ENOUGH.
SPECIFICS FOR KSTL...DETERIORATING CONDITIONS EXPECTED LATE
TONIGHT AND EARLY FRIDAY MORNING WITH IFR POSSIBLE BUT FOR NOW
HAVE FAVORED THE LO-END MVFR OF THE PREVIOUS TAF...IMPROVEMENT TO
CIGS ABOVE 2KFT EXPECTED ON FRIDAY WITH PARTIAL CLEARING AND
PERHAPS ANOTHER ROUND OF LO STRATUS AND FOG FRIDAY NIGHT. BEST
PCPN CHCS AFTER EARLY THIS EVENING WILL BE FRIDAY AFTERNOON WITH
TSRA DEVELOPING WITH THE HEATING OF THE DAY.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
855 PM MDT Sat May 18 2013
.DISCUSSION...
Update forthcoming. Showers and isolated weak thunderstorms continue
across the area. No reports of severe criteria with only very small
hail reorted 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 00Z.
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 will be possible until sunset...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 BILLINGS MT
923 AM MDT FRI MAY 17 2013
.UPDATE...
FORECAST IS IN GOOD SHAPE TODAY AND ONLY MADE SOME MINOR CHANGES.
PATCHY FOG STILL ON GOING FROM BAKER SOUTHWARD TO NEAR EKALAKA THIS
MORNING. THE PATCHY FOG IS EXPECTED TO PERSIST THROUGH LATE
MORNING.
SEVERE WEATHER THREAT FOR LATE THIS AFTERNOON INTO EARLY EVENING
STILL LOOKS GOOD FROM BROADUS TO EKALAKA. 12Z NAM SURFACE BASED
CAPE NEAR 1000 J/KG IN THE ABOVE MENTION AREAS AND THE THREAT OF
LARGE HAIL WILL BE POSSIBLE ALONG WITH HEAVY RAIN. FLASH FLOOD
WATCH ALSO LOOKS GOOD AS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
TRACK OVER THE BURN SCARS OF LAST YEARS FIRES IN SOUTHEAST
MONTANA. MODELS ALL INDICATING OVER A HALF INCH OF PRECIPITATION
IN THESE AREAS FROM LATE THIS AFTERNOON INTO THIS EVENING. WPC
ALSO PROGGING NEARLY A HALF INCH OF QPF TODAY IN THESE AREAS AS
WELL AS FROM LIVINGSTON TO BILLINGS. WILL KEEP FLASH FLOOD WATCH
IN PLACE FOR PORTIONS OS SOUTHEAST MONTANA AS STRONG FORCING FROM
UPPER TROUGH OF LOW PRESSURE MOVES IN OVER THE AREA. THERE MAY BE
A NEED TO EXTEND THE FLASH FLOOD WATCH THROUGH SUNDAY MORNING BUT
WILL EVALUATE THIS WITH THE AFTERNOON FORECAST PACKAGE. RICHMOND
&&
.SHORT TERM...VALID FOR TDY AND SAT...
BENEFICIAL MOISTURE IS ON THE WAY THE NEXT SEVERAL DAYS THANKS
TO A 500-HPA TROUGH. UP TO AN INCH OF RAINFALL IS VERY POSSIBLE
OVER MANY AREAS WHEN ALL IS SAID AND DONE...SO FORECAST POPS HAVE
ONCE AGAIN BEEN LEVERAGED UPWARD WITH THIS FORECAST SO THAT 80
PERCENT PROBABILITIES OF MOISTURE ARE ADVERTISED IN AT LEAST SOME
PERIODS OF THE FORECAST. HIGHS HAVE ALSO BEEN LOWERED TODAY AND
SAT BASED ON EXPECTED CLOUD COVER AND PRECIPITATION.
TODAY...DIFFLUENCE ASSOCIATED WITH A MODEST 300-HPA JET STREAK ON
THE ORDER OF 60 TO 70 KT SHOULD HELP SHOWERS BLOSSOM ACROSS SOUTH
CENTRAL MT THIS MORNING. BILLINGS MAY BE ON THE EAST EDGE OF THIS
MOISTURE BASED ON RECENT RAP AND HRRR RUNS. THEN...BY AFTERNOON A
DESTABILIZING BOUNDARY LAYER AND EASTWARD MOVEMENT OF THE DYNAMIC
FORCING TIED TO THE UPPER-LEVEL JET SHOULD FOSTER CONVECTION EAST
OF THE MORNING PRECIPITATION. THE 00 UTC GFS...ECMWF...AND RECENT
RAP AND HRRR RUNS ALL AGREE WELL ON THIS NOTION. BOTH THE ARW AND
NMM CORES OF THE HIGH-RESOLUTION...CONVECTION-ALLOWING WRF MODELS
MAKING UP THE SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY ALSO KEY IN
ON THIS CONVECTION...WHICH SHOULD FORM SOMEWHERE ALONG A BILLINGS
TO GREYBULL LINE IN THE 18 TO 21 UTC TIME FRAME. INSTABILITY WILL
BE SUFFICIENT FOR AT LEAST EMBEDDED THUNDER...AND AS THE ACTIVITY
GETS INTO SOUTHEASTERN MT...IT WILL HAVE ACCESS TO MUCAPE UPWARDS
OF 1000 J/KG. GIVEN STEEPENING MID-LEVEL LAPSE RATES AND 50 KT OF
0-6 KM BULK SHEAR...THERE IS ENOUGH OF A RISK OF SEVERE STORMS IN
THE BROADUS AND EKALAKA CORRIDOR IN PARTICULAR FOR US TO MAINTAIN
A MENTION OF IT IN THE FORECAST. LARGE HAIL SHOULD BE THE PRIMARY
THREAT. HOWEVER...QUESTIONS ABOUT DESTABILIZATION EXIST /WITH THE
00 UTC NAM SUGGESTING LOWER MUCAPE/ OWING TO CLOUD COVER...AND IT
IS STILL POSSIBLE SHEAR WILL BE TOO STRONG FOR LONG-LIVED OR DEEP
UPDRAFTS TO SUSTAIN THEMSELVES. NOTE THAT THERE IS A RISK OF SOME
ISOLATED STORMS FORMING IN SOUTHEASTERN MT DURING PEAK HEATING IN
ADVANCE OF THE ACTIVITY WE EXPECT TO MOVE INTO THAT AREA BY LATER
IN THE AFTERNOON OR EVENING...THOUGH CONFIDENCE IN THAT IS LOW.
TONIGHT...WE KEPT A MENTION OF SEVERE WEATHER IN THE FORECAST FOR
FAR SOUTHEASTERN MT AND PARTS OF SHERIDAN COUNTY WY UNTIL 06 UTC.
SREF-BASED SEVERE THUNDERSTORM PROBABILITIES SUGGEST THE RISK MAY
CONTINUE /AT LEAST ON A MARGINAL BASIS/ FOR A WHILE AFTER SUNSET.
OTHERWISE...OUR POP FORECAST IS BASED ON THE IDEA THAT A RELATIVE
BREAK IN MORE WIDESPREAD PRECIPITATION COULD OCCUR AFTER ABOUT 06
UTC AS CONVECTION SHIFTS INTO THE DAKOTAS AND AS THE FORCING FROM
THE 300-HPA JET SHIFTS INTO NORTHERN MT. THE 03 UTC SREF ARGUES A
DIFFERENT STORY THOUGH SINCE IT BRINGS ANOTHER MORE DEFINED BATCH
OF FORCING AND SHOWERS INTO SOUTH CENTRAL MT AFTER MIDNIGHT. THAT
IS A GOOD EXAMPLE OF THE SUBTLE DETAILS THAT ARE STILL NOT WORKED
OUT WITH THIS EVENT.
BY SAT...CONFIDENCE IN THE FORECAST STARTS DECREASING A BIT SINCE
GUIDANCE BEGINS SHOWING SOME DIFFERENCES IN HOW IT HANDLES ENERGY
ASSOCIATED WITH THE MID- AND UPPER-LEVEL TROUGH. ADD TO THAT SOME
GRID-SCALE FEEDBACK RELATED TO MODEL CONVECTIVE SCHEMES AND THERE
ARE CERTAINLY UNCERTAINTIES TO CONTEND WITH. THE GFS SOLUTION WAS
LEAST ROBUST WITH QPF OVER SOUTHERN MT...BUT IT ALSO SUFFERS MORE
FROM GRID-SCALE FEEDBACK THAN MOST OTHER SOLUTIONS...AND IT LOOKS
LIKE A RELATIVE OUTLIER. THE REST OF THE GUIDANCE IS WETTER...AND
SO WE CAUTIOUSLY PUSHED POPS UPWARD ANOTHER NOTCH IN MANY PLACES.
MID-LEVEL LAPSE RATES STAY MARGINALLY FAVORABLE FOR THUNDER...AND
SO WE KEPT AT LEAST AN ISOLATED MENTION OF IT IN THE FORECAST FOR
SAT AND SAT NIGHT. SCHULTZ
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
STILL SOME UNCERTAINTY ON WHETHER THE WET SCENARIO WILL HANG ON
SUNDAY AND MONDAY. THE NAM AND ECMWF WERE INDICATING THAT IT WOULD
AS THEY CUT A LOW OFF OVER WESTERN SOUTH DAKOTA AND VERY SLOWLY
DRIFT IT EAST MONDAY. THIS WOULD WRAP SOME DECENT MOISTURE AROUND
THE LOW INTO THE FORECAST AREA WITH STRONG UPSLOPE FLOW. THE
GFS...ON THE OTHER HAND...MOVES THE UPPER LOW FARTHER EAST MUCH
QUICKER. BOTH THE ECMWF AND GFS HAVE BEEN CONSISTENT WITH THEIR
SOLUTIONS. DID RAISE POPS FOR SUNDAY AND MONDAY AS THE GFS WAS THE
ODD MODEL OUT ON THE DRIER SIDE OF THINGS. DID LOWER TEMPERATURES
SUNDAY AND MONDAY GOING WITH A WETTER SCENARIO.
A BIT OF BLOCKING PATTERN SETS UP FOR WEDNESDAY THROUGH NEXT
FRIDAY AS AN UPPER RIDGE PINCHES OFF FROM WYOMING INTO SOUTHERN
CANADA. THE HIGH WILL BE PLACED BETWEEN THE UPPER LOW TO THE EAST
AND ANOTHER MUCH DEEPER LOW MOVING INTO WASHINGTON. THE WESTERN
UPPER LOW DOES NUDGE THINGS EAST WEDNESDAY AND PRODUCES SOUTHERLY
FLOW OVER WYOMING AND MONTANA. ORDINARILY A SOUTH FLOW WOULD MEAN
PRECIPITATION...BUT MODELS WERE PULLING IN DRIER MID LEVEL AIR. A
SERIES OF WEAK SHORTWAVES SPIN OFF THE WESTERN LOW AND TRAVERSE
THROUGH THE AREA THROUGH THE END OF THE EXTENDED FOR ASCENT. WILL
HAVE TO LOOK OUT FOR LOW LEVEL MOISTURE INCREASING HOWEVER AS
SOUTHEAST FLOW DEVELOPS OVER THE EASTERN HALF OF THE FORECAST
AREA. WILL BROAD BRUSH LOW POPS FOR NOW AND WAIT AND SEE HOW THIS
PATTERN PANS OUT. TWH
&&
.AVIATION...
SCATTERED SHOWERS THIS MORNING WILL BECOME MORE WIDESPREAD BY
EARLY AFTERNOON. THERE WILL BE THUNDERSTORMS EMBEDDED WITHIN THE
SHOWERS BUT THE MOST LIKELY LOCATION FOR ORGANIZED THUNDERSTORMS
WILL BE EAST OF KBIL AND INTO SOUTHEAST MONTANA. SOME OF THE
SHOWERS WILL CONTAIN MODERATE TO BRIEFLY HEAVY RAIN AND COULD
LOWER CONDITIONS TO MVFR. SOME THUNDERSTORMS COULD BE QUITE STRONG
FROM LOCATIONS EAST AND SOUTH OF A KSHR TO KMLS LINE WITH SOME
HAIL. MOUNTAINS WILL BE OBSCURED. TWH/FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 065 053/065 049/061 048/062 045/071 047/071 049/071
8/T 88/T 75/T 55/W 31/B 13/T 31/B
LVM 061 043/063 043/057 040/059 037/066 041/071 040/067
8/T 88/T 84/T 55/W 31/B 23/T 33/T
HDN 070 053/067 048/062 047/062 044/071 045/073 049/074
8/T 88/T 75/T 66/W 31/E 13/T 31/B
MLS 072 055/068 049/065 049/062 046/068 046/071 050/071
6/T 88/T 75/T 65/W 53/W 23/T 32/T
4BQ 074 054/068 047/063 047/060 043/063 044/071 048/071
6/T 87/T 65/T 66/W 53/W 22/T 22/T
BHK 071 053/068 047/062 047/060 043/061 043/067 048/067
5/T 77/T 65/T 65/W 53/W 22/W 22/T
SHR 072 048/065 044/059 043/057 040/064 040/073 046/072
6/T 57/T 65/T 66/W 42/W 13/T 31/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES
30-31-36>38-57-58.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
552 AM MDT FRI MAY 17 2013
.UPDATE...
RECENT HIGH-RESOLUTION MODEL GUIDANCE CONTINUES TO SUPPORT STORMS
FIRING OVER NORTH CENTRAL WY AND SOUTH CENTRAL MT THIS AFTERNOON.
THERE IS A GROWING CONSENSUS FOR THE STORMS TO TRACK OVER SEVERAL
OF THE BURN SCARS FROM THE 2012 WILDFIRES...WHICH POSES A RISK OF
FLASH FLOODING AND DEBRIS FLOWS. SEVERAL DIFFERENT FLAVORS OF THE
AVAILABLE HIGH-RESOLUTION GUIDANCE SHOW AN INCH OR MORE OF QPF IN
PARTS OF SOUTH CENTRAL AND SOUTHEASTERN MT BETWEEN 21 AND 06 UTC.
THAT IS A VERY REALISTIC POSSIBILITY EVEN WITH FAST STORM MOTIONS
GIVEN PRECIPITABLE WATER VALUES NEAR AN INCH. THUS...WE DEEMED IT
NECESSARY TO ISSUE A FLASH FLOOD WATCH FROM 18 UTC TODAY THROUGH
12 UTC SAT MORNING OVER THE BURN SCAR AREAS OF SOUTH CENTRAL AND
SOUTHEASTERN MT.
SOME PATCHY FOG IS ALSO OCCURRING AT BAKER AS OF 1145 UTC...SO AS
LONG AS WE WERE UPDATING THE FORECAST...WE ADDED THAT IN UNTIL 15
UTC IN FAR SOUTHEASTERN MT. SCHULTZ
&&
.SHORT TERM...VALID FOR TDY AND SAT...
BENEFICIAL MOISTURE IS ON THE WAY THE NEXT SEVERAL DAYS THANKS TO
A 500-HPA TROUGH. UP TO AN INCH OF RAINFALL IS VERY POSSIBLE OVER
MANY AREAS WHEN ALL IS SAID AND DONE...SO FORECAST POPS HAVE ONCE
AGAIN BEEN LEVERAGED UPWARD WITH THIS FORECAST SO THAT 80 PERCENT
PROBABILITIES OF MOISTURE ARE ADVERTISED IN AT LEAST SOME PERIODS
OF THE FORECAST. HIGHS HAVE ALSO BEEN LOWERED TODAY AND SAT BASED
ON EXPECTED CLOUD COVER AND PRECIPITATION.
TODAY...DIFFLUENCE ASSOCIATED WITH A MODEST 300-HPA JET STREAK ON
THE ORDER OF 60 TO 70 KT SHOULD HELP SHOWERS BLOSSOM ACROSS SOUTH
CENTRAL MT THIS MORNING. BILLINGS MAY BE ON THE EAST EDGE OF THIS
MOISTURE BASED ON RECENT RAP AND HRRR RUNS. THEN...BY AFTERNOON A
DESTABILIZING BOUNDARY LAYER AND EASTWARD MOVEMENT OF THE DYNAMIC
FORCING TIED TO THE UPPER-LEVEL JET SHOULD FOSTER CONVECTION EAST
OF THE MORNING PRECIPITATION. THE 00 UTC GFS...ECMWF...AND RECENT
RAP AND HRRR RUNS ALL AGREE WELL ON THIS NOTION. BOTH THE ARW AND
NMM CORES OF THE HIGH-RESOLUTION...CONVECTION-ALLOWING WRF MODELS
MAKING UP THE SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY ALSO KEY IN
ON THIS CONVECTION...WHICH SHOULD FORM SOMEWHERE ALONG A BILLINGS
TO GREYBULL LINE IN THE 18 TO 21 UTC TIME FRAME. INSTABILITY WILL
BE SUFFICIENT FOR AT LEAST EMBEDDED THUNDER...AND AS THE ACTIVITY
GETS INTO SOUTHEASTERN MT...IT WILL HAVE ACCESS TO MUCAPE UPWARDS
OF 1000 J/KG. GIVEN STEEPENING MID-LEVEL LAPSE RATES AND 50 KT OF
0-6 KM BULK SHEAR...THERE IS ENOUGH OF A RISK OF SEVERE STORMS IN
THE BROADUS AND EKALAKA CORRIDOR IN PARTICULAR FOR US TO MAINTAIN
A MENTION OF IT IN THE FORECAST. LARGE HAIL SHOULD BE THE PRIMARY
THREAT. HOWEVER...QUESTIONS ABOUT DESTABILIZATION EXIST /WITH THE
00 UTC NAM SUGGESTING LOWER MUCAPE/ OWING TO CLOUD COVER...AND IT
IS STILL POSSIBLE SHEAR WILL BE TOO STRONG FOR LONG-LIVED OR DEEP
UPDRAFTS TO SUSTAIN THEMSELVES. NOTE THAT THERE IS A RISK OF SOME
ISOLATED STORMS FORMING IN SOUTHEASTERN MT DURING PEAK HEATING IN
ADVANCE OF THE ACTIVITY WE EXPECT TO MOVE INTO THAT AREA BY LATER
IN THE AFTERNOON OR EVENING...THOUGH CONFIDENCE IN THAT IS LOW.
TONIGHT...WE KEPT A MENTION OF SEVERE WEATHER IN THE FORECAST FOR
FAR SOUTHEASTERN MT AND PARTS OF SHERIDAN COUNTY WY UNTIL 06 UTC.
SREF-BASED SEVERE THUNDERSTORM PROBABILITIES SUGGEST THE RISK MAY
CONTINUE /AT LEAST ON A MARGINAL BASIS/ FOR A WHILE AFTER SUNSET.
OTHERWISE...OUR POP FORECAST IS BASED ON THE IDEA THAT A RELATIVE
BREAK IN MORE WIDESPREAD PRECIPITATION COULD OCCUR AFTER ABOUT 06
UTC AS CONVECTION SHIFTS INTO THE DAKOTAS AND AS THE FORCING FROM
THE 300-HPA JET SHIFTS INTO NORTHERN MT. THE 03 UTC SREF ARGUES A
DIFFERENT STORY THOUGH SINCE IT BRINGS ANOTHER MORE DEFINED BATCH
OF FORCING AND SHOWERS INTO SOUTH CENTRAL MT AFTER MIDNIGHT. THAT
IS A GOOD EXAMPLE OF THE SUBTLE DETAILS THAT ARE STILL NOT WORKED
OUT WITH THIS EVENT.
BY SAT...CONFIDENCE IN THE FORECAST STARTS DECREASING A BIT SINCE
GUIDANCE BEGINS SHOWING SOME DIFFERENCES IN HOW IT HANDLES ENERGY
ASSOCIATED WITH THE MID- AND UPPER-LEVEL TROUGH. ADD TO THAT SOME
GRID-SCALE FEEDBACK RELATED TO MODEL CONVECTIVE SCHEMES AND THERE
ARE CERTAINLY UNCERTAINTIES TO CONTEND WITH. THE GFS SOLUTION WAS
LEAST ROBUST WITH QPF OVER SOUTHERN MT...BUT IT ALSO SUFFERS MORE
FROM GRID-SCALE FEEDBACK THAN MOST OTHER SOLUTIONS...AND IT LOOKS
LIKE A RELATIVE OUTLIER. THE REST OF THE GUIDANCE IS WETTER...AND
SO WE CAUTIOUSLY PUSHED POPS UPWARD ANOTHER NOTCH IN MANY PLACES.
MID-LEVEL LAPSE RATES STAY MARGINALLY FAVORABLE FOR THUNDER...AND
SO WE KEPT AT LEAST AN ISOLATED MENTION OF IT IN THE FORECAST FOR
SAT AND SAT NIGHT. SCHULTZ
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
STILL SOME UNCERTAINTY ON WHETHER THE WET SCENARIO WILL HANG ON
SUNDAY AND MONDAY. THE NAM AND ECMWF WERE INDICATING THAT IT WOULD
AS THEY CUT A LOW OFF OVER WESTERN SOUTH DAKOTA AND VERY SLOWLY
DRIFT IT EAST MONDAY. THIS WOULD WRAP SOME DECENT MOISTURE AROUND
THE LOW INTO THE FORECAST AREA WITH STRONG UPSLOPE FLOW. THE
GFS...ON THE OTHER HAND...MOVES THE UPPER LOW FARTHER EAST MUCH
QUICKER. BOTH THE ECMWF AND GFS HAVE BEEN CONSISTENT WITH THEIR
SOLUTIONS. DID RAISE POPS FOR SUNDAY AND MONDAY AS THE GFS WAS THE
ODD MODEL OUT ON THE DRIER SIDE OF THINGS. DID LOWER TEMPERATURES
SUNDAY AND MONDAY GOING WITH A WETTER SCENARIO.
A BIT OF BLOCKING PATTERN SETS UP FOR WEDNESDAY THROUGH NEXT
FRIDAY AS AN UPPER RIDGE PINCHES OFF FROM WYOMING INTO SOUTHERN
CANADA. THE HIGH WILL BE PLACED BETWEEN THE UPPER LOW TO THE EAST
AND ANOTHER MUCH DEEPER LOW MOVING INTO WASHINGTON. THE WESTERN
UPPER LOW DOES NUDGE THINGS EAST WEDNESDAY AND PRODUCES SOUTHERLY
FLOW OVER WYOMING AND MONTANA. ORDINARILY A SOUTH FLOW WOULD MEAN
PRECIPITATION...BUT MODELS WERE PULLING IN DRIER MID LEVEL AIR. A
SERIES OF WEAK SHORTWAVES SPIN OFF THE WESTERN LOW AND TRAVERSE
THROUGH THE AREA THROUGH THE END OF THE EXTENDED FOR ASCENT. WILL
HAVE TO LOOK OUT FOR LOW LEVEL MOISTURE INCREASING HOWEVER AS
SOUTHEAST FLOW DEVELOPS OVER THE EASTERN HALF OF THE FORECAST
AREA. WILL BROAD BRUSH LOW POPS FOR NOW AND WAIT AND SEE HOW THIS
PATTERN PANS OUT. TWH
&&
.AVIATION...
SCATTERED SHOWERS THIS MORNING WILL BECOME MORE WIDESPREAD BY
EARLY AFTERNOON. THERE WILL BE THUNDERSTORMS EMBEDDED WITHIN THE
SHOWERS BUT THE MOST LIKELY LOCATION FOR ORGANIZED THUNDERSTORMS
WILL BE EAST OF KBIL. SOME OF THE SHOWERS WILL CONTAIN MODERATE TO
BRIEFLY HEAVY RAIN AND COULD LOWER CONDITIONS TO MVFR. SOME
THUNDERSTORMS COULD BE QUITE STRONG FROM LOCATIONS EAST AND SOUTH
OF A KSHR TO KMLS LINE. MOUNTAINS WILL BE OBSCURED. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 065 053/065 049/061 048/062 045/071 047/071 049/071
8/T 88/T 75/T 55/W 31/B 13/T 31/B
LVM 061 043/063 043/057 040/059 037/066 041/071 040/067
8/T 88/T 84/T 55/W 31/B 23/T 33/T
HDN 070 053/067 048/062 047/062 044/071 045/073 049/074
8/T 88/T 75/T 66/W 31/E 13/T 31/B
MLS 072 055/068 049/065 049/062 046/068 046/071 050/071
6/T 88/T 75/T 65/W 53/W 23/T 32/T
4BQ 074 054/068 047/063 047/060 043/063 044/071 048/071
6/T 87/T 65/T 66/W 53/W 22/T 22/T
BHK 071 053/068 047/062 047/060 043/061 043/067 048/067
5/T 77/T 65/T 65/W 53/W 22/W 22/T
SHR 072 048/065 044/059 043/057 040/064 040/073 046/072
6/T 57/T 65/T 66/W 42/W 13/T 31/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT FROM NOON MDT TODAY THROUGH LATE
TONIGHT FOR ZONES 30-31-36>38-57-58.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
346 AM MDT FRI MAY 17 2013
.SHORT TERM...VALID FOR TDY AND SAT...
BENEFICIAL MOISTURE IS ON THE WAY THE NEXT SEVERAL DAYS THANKS TO
A 500-HPA TROUGH. UP TO AN INCH OF RAINFALL IS VERY POSSIBLE OVER
MANY AREAS WHEN ALL IS SAID AND DONE...SO FORECAST POPS HAVE ONCE
AGAIN BEEN LEVERAGED UPWARD WITH THIS FORECAST SO THAT 80 PERCENT
PROBABILITIES OF MOISTURE ARE ADVERTISED IN AT LEAST SOME PERIODS
OF THE FORECAST. HIGHS HAVE ALSO BEEN LOWERED TODAY AND SAT BASED
ON EXPECTED CLOUD COVER AND PRECIPITATION.
TODAY...DIFFLUENCE ASSOCIATED WITH A MODEST 300-HPA JET STREAK ON
THE ORDER OF 60 TO 70 KT SHOULD HELP SHOWERS BLOSSOM ACROSS SOUTH
CENTRAL MT THIS MORNING. BILLINGS MAY BE ON THE EAST EDGE OF THIS
MOISTURE BASED ON RECENT RAP AND HRRR RUNS. THEN...BY AFTERNOON A
DESTABILIZING BOUNDARY LAYER AND EASTWARD MOVEMENT OF THE DYNAMIC
FORCING TIED TO THE UPPER-LEVEL JET SHOULD FOSTER CONVECTION EAST
OF THE MORNING PRECIPITATION. THE 00 UTC GFS...ECMWF...AND RECENT
RAP AND HRRR RUNS ALL AGREE WELL ON THIS NOTION. BOTH THE ARW AND
NMM CORES OF THE HIGH-RESOLUTION...CONVECTION-ALLOWING WRF MODELS
MAKING UP THE SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY ALSO KEY IN
ON THIS CONVECTION...WHICH SHOULD FROM SOMEWHERE ALONG A BILLINGS
TO GREYBULL LINE IN THE 18 TO 21 UTC TIME FRAME. INSTABILITY WILL
BE SUFFICIENT FOR AT LEAST EMBEDDED THUNDER...AND AS THE ACTIVITY
GETS INTO SOUTHEASTERN MT...IT WILL HAVE ACCESS TO MUCAPE UPWARDS
OF 1000 J/KG. GIVEN STEEPENING MID-LEVEL LAPSE RATES AND 50 KT OF
0-6 KM BULK SHEAR...THERE IS ENOUGH OF A RISK OF SEVERE STORMS IN
THE BROADUS AND EKALAKA CORRIDOR IN PARTICULAR FOR US TO MAINTAIN
A MENTION OF IT IN THE FORECAST. LARGE HAIL SHOULD BE THE PRIMARY
THREAT. HOWEVER...QUESTIONS ABOUT DESTABILIZATION EXIST /WITH THE
00 UTC NAM SUGGESTING LOWER MUCAPE/ OWING TO CLOUD COVER...AND IT
IS STILL POSSIBLE SHEAR WILL BE TOO STRONG FOR LONG-LIVED OR DEEP
UPDRAFTS TO SUSTAIN THEMSELVES. NOTE THAT THERE IS A RISK OF SOME
ISOLATED STORMS FORMING IN SOUTHEASTERN MT DURING PEAK HEATING IN
ADVANCE OF THE ACTIVITY WE EXPECT TO MOVE INTO THAT AREA BY LATER
IN THE AFTERNOON OR EVENING...THOUGH CONFIDENCE IN THAT IS LOW.
TONIGHT...WE KEPT A MENTION OF SEVERE WEATHER IN THE FORECAST FOR
FAR SOUTHEASTERN MT AND PARTS OF SHERIDAN COUNTY WY UNTIL 06 UTC.
SREF-BASED SEVERE THUNDERSTORM PROBABILITIES SUGGEST THE RISK MAY
CONTINUE /AT LEAST ON A MARGINAL BASIS/ FOR A WHILE AFTER SUNSET.
OTHERWISE...OUR POP FORECAST IS BASED ON THE IDEA THAT A RELATIVE
BREAK IN MORE WIDESPREAD PRECIPITATION COULD OCCUR AFTER ABOUT 06
UTC AS CONVECTION SHIFTS INTO THE DAKOTAS AND AS THE FORCING FROM
THE 300-HPA JET SHIFTS INTO NORTHERN MT. THE 03 UTC SREF ARGUES A
DIFFERENT STORY THOUGH SINCE IT BRINGS ANOTHER MORE DEFINED BATCH
OF FORCING AND SHOWERS INTO SOUTH CENTRAL MT AFTER MIDNIGHT. THAT
IS A GOOD EXAMPLE OF THE SUBTLE DETAILS THAT ARE STILL NOT WORKED
OUT WITH THIS EVENT.
BY SAT...CONFIDENCE IN THE FORECAST STARTS DECREASING A BIT SINCE
GUIDANCE BEGINS SHOWING SOME DIFFERENCES IN HOW IT HANDLES ENERGY
ASSOCIATED WITH THE MID- AND UPPER-LEVEL TROUGH. ADD TO THAT SOME
GRID-SCALE FEEDBACK RELATED TO MODEL CONVECTIVE SCHEMES AND THERE
ARE CERTAINLY UNCERTAINTIES TO CONTEND WITH. THE GFS SOLUTION WAS
LEAST ROBUST WITH QPF OVER SOUTHERN MT...BUT IT ALSO SUFFERS MORE
FROM GRID-SCALE FEEDBACK THAN MOST OTHER SOLUTIONS...AND IT LOOKS
LIKE A RELATIVE OUTLIER. THE REST OF THE GUIDANCE IS WETTER...AND
SO WE CAUTIOUSLY PUSHED POPS UPWARD ANOTHER NOTCH IN MANY PLACES.
MID-LEVEL LAPSE RATES STAY MARGINALLY FAVORABLE FOR THUNDER...AND
SO WE KEPT AT LEAST AN ISOLATED MENTION OF IT IN THE FORECAST FOR
SAT AND SAT NIGHT. SCHULTZ
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
STILL SOME UNCERTAINTY ON WHETHER THE WET SCENARIO WILL HANG ON
SUNDAY AND MONDAY. THE NAM AND ECMWF WERE INDICATING THAT IT WOULD
AS THEY CUT A LOW OFF OVER WESTERN SOUTH DAKOTA AND VERY SLOWLY
DRIFT IT EAST MONDAY. THIS WOULD WRAP SOME DECENT MOISTURE AROUND
THE LOW INTO THE FORECAST AREA WITH STRONG UPSLOPE FLOW. THE
GFS...ON THE OTHER HAND...MOVES THE UPPER LOW FARTHER EAST MUCH
QUICKER. BOTH THE ECMWF AND GFS HAVE BEEN CONSISTENT WITH THEIR
SOLUTIONS. DID RAISE POPS FOR SUNDAY AND MONDAY AS THE GFS WAS THE
ODD MODEL OUT ON THE DRIER SIDE OF THINGS. DID LOWER TEMPERATURES
SUNDAY AND MONDAY GOING WITH A WETTER SCENARIO.
A BIT OF BLOCKING PATTERN SETS UP FOR WEDNESDAY THROUGH NEXT
FRIDAY AS AN UPPER RIDGE PINCHES OFF FROM WYOMING INTO SOUTHERN
CANADA. THE HIGH WILL BE PLACED BETWEEN THE UPPER LOW TO THE EAST
AND ANOTHER MUCH DEEPER LOW MOVING INTO WASHINGTON. THE WESTERN
UPPER LOW DOES NUDGE THINGS EAST WEDNESDAY AND PRODUCES SOUTHERLY
FLOW OVER WYOMING AND MONTANA. ORDINARILY A SOUTH FLOW WOULD MEAN
PRECIPITATION...BUT MODELS WERE PULLING IN DRIER MID LEVEL AIR. A
SERIES OF WEAK SHORTWAVES SPIN OFF THE WESTERN LOW AND TRAVERSE
THROUGH THE AREA THROUGH THE END OF THE EXTENDED FOR ASCENT. WILL
HAVE TO LOOK OUT FOR LOW LEVEL MOISTURE INCREASING HOWEVER AS
SOUTHEAST FLOW DEVELOPS OVER THE EASTERN HALF OF THE FORECAST
AREA. WILL BROAD BRUSH LOW POPS FOR NOW AND WAIT AND SEE HOW THIS
PATTERN PANS OUT. TWH
&&
.AVIATION...
SCATTERED SHOWERS THIS MORNING WILL BECOME MORE WIDESPREAD BY
EARLY AFTERNOON. THERE WILL BE THUNDERSTORMS EMBEDDED WITHIN THE
SHOWERS BUT THE MOST LIKELY LOCATION FOR ORGANIZED THUNDERSTORMS
WILL BE EAST OF KBIL. SOME OF THE SHOWERS WILL CONTAIN MODERATE TO
BRIEFLY HEAVY RAIN AND COULD LOWER CONDITIONS TO MVFR. SOME
THUNDERSTORMS COULD BE QUITE STRONG FROM LOCATIONS EAST AND SOUTH
OF A KSHR TO KMLS LINE. MOUNTAINS WILL BE OBSCURED. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 065 053/065 049/061 048/062 045/071 047/071 049/071
8/T 88/T 75/T 55/W 31/B 13/T 31/B
LVM 061 043/063 043/057 040/059 037/066 041/071 040/067
8/T 88/T 84/T 55/W 31/B 23/T 33/T
HDN 070 053/067 048/062 047/062 044/071 045/073 049/074
8/T 88/T 75/T 66/W 31/E 13/T 31/B
MLS 072 055/068 049/065 049/062 046/068 046/071 050/071
6/T 88/T 75/T 65/W 53/W 23/T 32/T
4BQ 074 054/068 047/063 047/060 043/063 044/071 048/071
6/T 87/T 65/T 66/W 53/W 22/T 22/T
BHK 071 053/068 047/062 047/060 043/061 043/067 048/067
5/T 77/T 65/T 65/W 53/W 22/W 22/T
SHR 072 048/065 044/059 043/057 040/064 040/073 046/072
6/T 57/T 65/T 66/W 42/W 13/T 31/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1100 PM MDT Thu May 16 2013
.DISCUSSION...
Update forthcoming. Have made adjustments to the pop and weather
grids. Moist and unstable flow aloft continues ahead of an upper
trof approaching from the west. Latest RUC analysis keeps overnight
precipitation mainly over the southwest so have lowered pops across
central and northern portions of the county warning area into Friday
morning. Remainder of forecast looks on track. Emanuel
&&
.AVIATION...
UPDATED 0500Z.
Moist and unstable flow will continue as an upper level trough moves
slowly east over the region. Disturbances will bring scattered to
numerous showers to the southern half of Central Montana through 00z
Friday. In the north VFR conditions should prevail tonight with
areas of MVFR in and around isolated showers before 12z. Central
Montana will see more widespread stratiform rain and mountain snow
develop after 12z spreading to North Central Montana after 18z.
Widespread MVFR/IFR conditions and mountain obscuration is expected.
&&
.PREV DISCUSSION...Issued 257 PM MDT Thu May 16 2013
Thursday through Saturday...Moist flow aloft and multiple weak
upper level disturbances will move across the area ahead of a low
pressure trough that will move across the area throughout the
weekend. Showers and afternoon thunderstorms will increase in
coverage through the weekend. No severe thunderstorms are expected
at this time however isolated strong gusty winds and hail will be
possible. The area with the largest chance of widespread
precipitation will continue to be Southwest Montana where low
level moisture will be the most abundant throughout the period.
Less chance of wide spread precipitation to the north as the Moist
flow at mid level dramatically decreases north of the Little Belt
Mountains. Suk
SATURDAY NIGHT THROUGH THURSDAY...FAIRLY GOOD MODEL AGREEMENT
THROUGH THE PERIOD. EXPECT AN UNSETTLED WEATHER PATTERN AS THE BROAD
UPPER TROUGH...ALREADY IN PLACE...MOVES EASTWARD. ON TUESDAY WEAK
RIDGING BUILDS INTO THE AREA. THE ECMWF HAS THE RIDGE BUILDING A
LITTLE STRONGER NORTH INTO MONTANA...BUT THE RIDGING IS SHORT LIVED.
BY TUESDAY NIGHT THE AREA HAS DIFFLUENT FLOW WHILE BETWEEN SYSTEMS.
BY WEDNESDAY MORNING THE CWA WILL START TO FEEL THE EFFECTS OF THE
LOW IN THE PAC NW. AS FAR AS PRECIPITATION GOES...MODEL SOUNDINGS
CONTINUE TO SHOW DEEP MOISTURE THROUGH MONDAY MORNING...BUT NOT AS
MUCH INSTABILITY. MOST OF PRECIPITATION WILL FALL AS RAIN WITH THE
EXCEPTION OF THE HIGHEST OF ELEVATIONS. THIS WEEKEND`S SYSTEM WILL
BRING MUCH NEEDED RAINFALL OVER MUCH OF THE STATE...WITH ADDITIONAL
CHANCES BY THE END OF NEXT WEEK. MERCER
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 64 45 61 44 / 50 50 70 50
CTB 64 42 63 41 / 50 40 50 40
HLN 65 46 63 45 / 50 60 80 60
BZN 66 42 62 41 / 50 70 80 70
WEY 61 43 56 39 / 60 60 70 60
DLN 63 43 59 41 / 70 70 80 80
HVR 71 47 68 46 / 50 60 60 50
LWT 64 46 59 43 / 50 80 70 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1221 PM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT FRI MAY 17 2013
ANOTHER SEASONABLY WARM AFTERNOON IS EXPECTED ACROSS THE REGION AS
WEAK UPPER LEVEL RIDING WORKS ITS WAY IN FROM THE WEST. EARLY THIS
MORNING...SOME SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED TO THE
WEST OF THE LOCAL AREA...LIKELY A FACTOR OF THE LOW LEVEL JET
PROVIDING JUST ENOUGH FORCING ACROSS WESTERN KANSAS EARLY THIS
MORNING TO SPARK SOME CONVECTION. HOWEVER WITH THIS ACTIVITY SHOWING
SIGNS OF DIMINISHING AND LITTLE INSTABILITY TO KEEP IT GOING AS IT
APPROACHES THE LOCAL AREA...DECIDED TO JUST ADD A SLIGHT CHANCE OF
SPRINKLES ACROSS THE WESTERN FRINGES OF OUR FORECAST AREA THROUGH 8
AM TO ACCOUNT FOR ANY REMNANTS OF THIS CONVECTION AS IT WORKS EAST.
OTHERWISE...HAVE SEEN SOME PATCHY FOG DEVELOP ACROSS AROUND LXN AND
ODX EARLY THIS MORNING AS TEMPERATURES HAVE FALLEN TO REACH THE
DEWPOINTS AT THESE LOCATIONS THE PAST COUPLE OF HOURS...AND THINK
SOME FURTHER DEVELOPMENT WILL BE POSSIBLE OVER THE NEXT FEW
HOURS...GENERALLY WEST OF HIGHWAY 281. HRRR AND SREF HAVE BOTH
BACKED OFF ON POTENTIAL FOG DEVELOPMENT FOR THIS MORNING...AND
EXPECT ANY FOG THAT DOES MANAGE TO DEVELOP TO BE FAIRLY PATCHY AND
SHORT LIVED...AND CORRESPONDINGLY TRIMMED BACK COVERAGE FROM PREVIOUS
FORECAST.
FOR THIS AFTERNOON...EXPECT TEMPERATURES TO CLIMB BACK INTO THE MID
AND UPPER 80S ACROSS THE ENTIRE FORECAST AREA AS PARTLY CLOUDY TO
MOSTLY SUNNY SKIES WILL WORK THEIR WAY IN ACROSS THE REGION AS THE
RIDGE TRANSITIONS EASTWARD. ADDITIONALLY...WITH THE RIDGE AXIS
MOVING OVERHEAD...850MB TEMPS WILL CLIMB A COUPLE OF DEGREES FROM
YESTERDAYS VALUES...FURTHER AIDING IN A SEASONABLY WARM AFTERNOON.
AT THE SURFACE...EXPECT A SURFACE TROUGH TO DEVELOP ON THE LEE SIDE
OF THE ROCKIES BY EARLY AFTERNOON...AND THIS SHOULD HELP INCREASE
THE PRESSURE GRADIENT JUST ENOUGH TO RESULT IN BREEZY SOUTHERLY
WINDS...GENERALLY 15 TO 25 MPH IN MOST SPOTS.
FOR TONIGHT...SOME OF THE GUIDANCE IS ATTEMPTING TO DEVELOP SOME
CONVECTION ACROSS THE HIGH PLAINS AND TRANSITION IT EASTWARD AROUND
SUNSET. WHILE THERE WILL BE PLENTY OF INSTABILITY TO JUSTIFY
CONVECTION TO OUR WEST...A DECENT CAP IS FORECAST AROUND 800 MB
WITH LITTLE IN THE WAY OF FORCING TO JUSTIFY MUCH CONVECTION
ACROSS THE LOCAL AREA. EVEN SO...WITH 00Z WRF BEING THE MOST
AGGRESSIVE TRANSLATING SOME OF THE REMNANTS OF THE HIGH PLAINS
CONVECTION ACROSS THE LOCAL AREA DURING THE EVENING HOURS...FELT
JUSTIFIED ADDING A FEW SPRINKLES TO THE NORTHWESTERN QUADRANT OF THE
LOCAL AREA JUST IN CASE A FEW SHOWERS ARE ABLE TO MAINTAIN
THEMSELVES AS THEY TRACK EAST.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 408 AM CDT FRI MAY 17 2013
THUNDERSTORM CHANCES THIS WEEKEND WILL BE THE PRIMARY FOCUS OF
LONG TERM. IT SHOULD BE NOTED THAT THERE ARE CHANCES FOR
PRECIPITATION NEARLY EVERYDAY OVER THE LONG TERM...BUT THE CHANCE
FOR SEVERE THUNDERSTORMS APPEARS TO BE BEST ON SATURDAY AT THE MOMENT.
AN UPPER LEVEL TROUGH WILL BEGIN TRANSITIONING OVER THE WEST COAST
TODAY AND WILL EVENTUALLY MOVE EASTWARD INTO THE INTERMOUNTAIN WEST
ON SATURDAY. AT THE SURFACE ON SATURDAY...A LEE LOW WILL FORM AHEAD
OF THE UPPER LEVEL TROUGH...AND A COLD FRONT WILL DRAPE INTO
NEBRASKA WHICH SHOULD HELP TO INITIATE THUNDERSTORMS ACROSS THE
OUTLOOK AREA LATER IN THE AFTERNOON. THERE WILL BE A STRONG
CAPPING INVERSION IN PLACE AT THE MID-LEVELS...SO THIS WILL NEED
TO ERODE/BREAK BEFORE ANY CONVECTION CAN INITIALIZE. A FEW THINGS
SHOULD HELP TO GET STORMS INITIATED LATER IN THE AFTERNOON THOUGH.
FOR ONE...THE ADVECTION OF STEEPER LAPSE RATES IN THE MID-LEVELS
WILL HELP WEAKEN THIS CAP. SECONDLY...THE COLD FRONT PROGGED TO
SLIDE OVER THE REGION SHOULD SERVE AS A GOOD LIFTING MECHANISM TO
HELP GET CONVECTION STARTED IN THE AFTERNOON. LASTLY...MODERATE TO
STRONG INSTABILITY ON THE ORDER OF 3000-4000 J/KG OF MLCAPE IS
FORECAST BY 00Z SUNDAY...SO ANY STORMS THAT DO FORM WILL HAVE THE
ABILITY TO BECOME STRONG TO SEVERE. AS THE EVENT UNFOLDS LATER
INTO THE EVENING...THE FORMATION ON AN MCS IS DEFINITELY POSSIBLY
AND SHOULD POSE A PRIMARY THREAT OF DAMAGING WINDS. HAIL WILL BE
THE PRIMARY THREAT EARLY IN THE EVENT...ESPECIALLY THE MORE
ISOLATED/DISCRETE CELLS WITH STRONG UPDRAFTS. ITS ALSO WORTH
NOTING THE NAM...GFS...AND EC ALL SHOW STRONG 0-1 KM BULK SHEAR ON
THE ORDER OF 25 TO 30 KTS. DEEP LAYER SHEAR WAS NOT AS IMPRESSIVE
BUT STILL HAD VALUES AROUND 35 KTS. THE SHEAR ENVIRONMENT COUPLED
WITH STRONG INSTABILITY WOULD SUGGEST SUPERCELLS COULD FORM AND
WITH ANY SUPERCELL...THERE WILL ALSO BE A TORNADO THREAT.
MOVING INTO SUNDAY...THUNDERSTORMS WILL LIKELY CONTINUE MOVING
EASTWARD ACROSS THE OUTLOOK AREA. THE SEVERE THREAT WILL BE OVERALL
LIMITED...BUT OUR EASTERN COUNTIES COULD POTENTIALLY SEE THE SEVERE
THREAT CONTINUE INTO THE AFTERNOON HOURS ON SUNDAY...PRIMARILY EAST
OF HIGHWAY 281. NEXT WEEK WILL HAVE POPS ANYWHERE FROM 10 TO 30
PERCENT NEARLY EVERYDAY. THESE POPS ARE ROOTED IN THE TROUGH
CURRENTLY OVER THE WEST COAST WHICH IS FORECAST TO MEANDER AROUND
THE GREAT PLAINS NEXT WEEK. THE BIGGEST DISADVANTAGE IN THE LONG
TERM IS THE LACK OF CONSISTENCY AND AGREEMENT BETWEEN THE MODELS.
THROUGH THE WEEKEND...TEMPERATURES WILL BE ABOVE NORMAL...WHILE NEXT
WEEK WILL BE CLOSER TO NORMAL FOR THIS TIME OF YEAR. HIGHS ON
TUESDAY APPEAR TO BE THE ONE EXCEPTION...WITH TEMPERATURES MORE
LIKELY TO BE SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1220 PM CDT FRI MAY 17 2013
A FEW CIRRUS ARE MOVING THROUGH THE KGRI TERMINAL AREA THIS
AFTERNOON AND WILL CONTINUE INTO THIS EVENING. LATE TONIGHT LOW
LEVEL MOISTURE WILL PUSH INTO THE AREA. THIS WILL BRING IN LOW
CLOUDS AND SOME FOG. EXPECT THERE TO BE IFR CONDITIONS. THERE IS
AN OFF CHANCE THAT THERE MAY BE SOME LIFR CONDITIONS...BUT WILL
WAIT TO SEE HOW MUCH OF THE LOW LEVEL MOISTURE GETS INTO THE KGRI
TERMINAL AREA.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...SAR
LONG TERM...GUERRERO
AVIATION...JCB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
551 AM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT FRI MAY 17 2013
ANOTHER SEASONABLY WARM AFTERNOON IS EXPECTED ACROSS THE REGION AS
WEAK UPPER LEVEL RIDING WORKS ITS WAY IN FROM THE WEST. EARLY THIS
MORNING...SOME SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED TO THE
WEST OF THE LOCAL AREA...LIKELY A FACTOR OF THE LOW LEVEL JET
PROVIDING JUST ENOUGH FORCING ACROSS WESTERN KANSAS EARLY THIS
MORNING TO SPARK SOME CONVECTION. HOWEVER WITH THIS ACTIVITY SHOWING
SIGNS OF DIMINISHING AND LITTLE INSTABILITY TO KEEP IT GOING AS IT
APPROACHES THE LOCAL AREA...DECIDED TO JUST ADD A SLIGHT CHANCE OF
SPRINKLES ACROSS THE WESTERN FRINGES OF OUR FORECAST AREA THROUGH 8
AM TO ACCOUNT FOR ANY REMNANTS OF THIS CONVECTION AS IT WORKS EAST.
OTHERWISE...HAVE SEEN SOME PATCHY FOG DEVELOP ACROSS AROUND LXN AND
ODX EARLY THIS MORNING AS TEMPERATURES HAVE FALLEN TO REACH THE
DEWPOINTS AT THESE LOCATIONS THE PAST COUPLE OF HOURS...AND THINK
SOME FURTHER DEVELOPMENT WILL BE POSSIBLE OVER THE NEXT FEW
HOURS...GENERALLY WEST OF HIGHWAY 281. HRRR AND SREF HAVE BOTH
BACKED OFF ON POTENTIAL FOG DEVELOPMENT FOR THIS MORNING...AND
EXPECT ANY FOG THAT DOES MANAGE TO DEVELOP TO BE FAIRLY PATCHY AND
SHORT LIVED...AND CORRESPONDINGLY TRIMMED BACK COVERAGE FROM PREVIOUS
FORECAST.
FOR THIS AFTERNOON...EXPECT TEMPERATURES TO CLIMB BACK INTO THE MID
AND UPPER 80S ACROSS THE ENTIRE FORECAST AREA AS PARTLY CLOUDY TO
MOSTLY SUNNY SKIES WILL WORK THEIR WAY IN ACROSS THE REGION AS THE
RIDGE TRANSITIONS EASTWARD. ADDITIONALLY...WITH THE RIDGE AXIS
MOVING OVERHEAD...850MB TEMPS WILL CLIMB A COUPLE OF DEGREES FROM
YESTERDAYS VALUES...FURTHER AIDING IN A SEASONABLY WARM AFTERNOON.
AT THE SURFACE...EXPECT A SURFACE TROUGH TO DEVELOP ON THE LEE SIDE
OF THE ROCKIES BY EARLY AFTERNOON...AND THIS SHOULD HELP INCREASE
THE PRESSURE GRADIENT JUST ENOUGH TO RESULT IN BREEZY SOUTHERLY
WINDS...GENERALLY 15 TO 25 MPH IN MOST SPOTS.
FOR TONIGHT...SOME OF THE GUIDANCE IS ATTEMPTING TO DEVELOP SOME
CONVECTION ACROSS THE HIGH PLAINS AND TRANSITION IT EASTWARD AROUND
SUNSET. WHILE THERE WILL BE PLENTY OF INSTABILITY TO JUSTIFY
CONVECTION TO OUR WEST...A DECENT CAP IS FORECAST AROUND 800 MB
WITH LITTLE IN THE WAY OF FORCING TO JUSTIFY MUCH CONVECTION
ACROSS THE LOCAL AREA. EVEN SO...WITH 00Z WRF BEING THE MOST
AGGRESSIVE TRANSLATING SOME OF THE REMNANTS OF THE HIGH PLAINS
CONVECTION ACROSS THE LOCAL AREA DURING THE EVENING HOURS...FELT
JUSTIFIED ADDING A FEW SPRINKLES TO THE NORTHWESTERN QUADRANT OF THE
LOCAL AREA JUST IN CASE A FEW SHOWERS ARE ABLE TO MAINTAIN
THEMSELVES AS THEY TRACK EAST.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 408 AM CDT FRI MAY 17 2013
THUNDERSTORM CHANCES THIS WEEKEND WILL BE THE PRIMARY FOCUS OF
LONG TERM. IT SHOULD BE NOTED THAT THERE ARE CHANCES FOR
PRECIPITATION NEARLY EVERYDAY OVER THE LONG TERM...BUT THE CHANCE
FOR SEVERE THUNDERSTORMS APPEARS TO BE BEST ON SATURDAY AT THE MOMENT.
AN UPPER LEVEL TROUGH WILL BEGIN TRANSITIONING OVER THE WEST COAST
TODAY AND WILL EVENTUALLY MOVE EASTWARD INTO THE INTERMOUNTAIN WEST
ON SATURDAY. AT THE SURFACE ON SATURDAY...A LEE LOW WILL FORM AHEAD
OF THE UPPER LEVEL TROUGH...AND A COLD FRONT WILL DRAPE INTO
NEBRASKA WHICH SHOULD HELP TO INITIATE THUNDERSTORMS ACROSS THE
OUTLOOK AREA LATER IN THE AFTERNOON. THERE WILL BE A STRONG
CAPPING INVERSION IN PLACE AT THE MID-LEVELS...SO THIS WILL NEED
TO ERODE/BREAK BEFORE ANY CONVECTION CAN INITIALIZE. A FEW THINGS
SHOULD HELP TO GET STORMS INITIATED LATER IN THE AFTERNOON THOUGH.
FOR ONE...THE ADVECTION OF STEEPER LAPSE RATES IN THE MID-LEVELS
WILL HELP WEAKEN THIS CAP. SECONDLY...THE COLD FRONT PROGGED TO
SLIDE OVER THE REGION SHOULD SERVE AS A GOOD LIFTING MECHANISM TO
HELP GET CONVECTION STARTED IN THE AFTERNOON. LASTLY...MODERATE TO
STRONG INSTABILITY ON THE ORDER OF 3000-4000 J/KG OF MLCAPE IS
FORECAST BY 00Z SUNDAY...SO ANY STORMS THAT DO FORM WILL HAVE THE
ABILITY TO BECOME STRONG TO SEVERE. AS THE EVENT UNFOLDS LATER
INTO THE EVENING...THE FORMATION ON AN MCS IS DEFINITELY POSSIBLY
AND SHOULD POSE A PRIMARY THREAT OF DAMAGING WINDS. HAIL WILL BE
THE PRIMARY THREAT EARLY IN THE EVENT...ESPECIALLY THE MORE
ISOLATED/DISCRETE CELLS WITH STRONG UPDRAFTS. ITS ALSO WORTH
NOTING THE NAM...GFS...AND EC ALL SHOW STRONG 0-1 KM BULK SHEAR ON
THE ORDER OF 25 TO 30 KTS. DEEP LAYER SHEAR WAS NOT AS IMPRESSIVE
BUT STILL HAD VALUES AROUND 35 KTS. THE SHEAR ENVIRONMENT COUPLED
WITH STRONG INSTABILITY WOULD SUGGEST SUPERCELLS COULD FORM AND
WITH ANY SUPERCELL...THERE WILL ALSO BE A TORNADO THREAT.
MOVING INTO SUNDAY...THUNDERSTORMS WILL LIKELY CONTINUE MOVING
EASTWARD ACROSS THE OUTLOOK AREA. THE SEVERE THREAT WILL BE OVERALL
LIMITED...BUT OUR EASTERN COUNTIES COULD POTENTIALLY SEE THE SEVERE
THREAT CONTINUE INTO THE AFTERNOON HOURS ON SUNDAY...PRIMARILY EAST
OF HIGHWAY 281. NEXT WEEK WILL HAVE POPS ANYWHERE FROM 10 TO 30
PERCENT NEARLY EVERYDAY. THESE POPS ARE ROOTED IN THE TROUGH
CURRENTLY OVER THE WEST COAST WHICH IS FORECAST TO MEANDER AROUND
THE GREAT PLAINS NEXT WEEK. THE BIGGEST DISADVANTAGE IN THE LONG
TERM IS THE LACK OF CONSISTENCY AND AGREEMENT BETWEEN THE MODELS.
THROUGH THE WEEKEND...TEMPERATURES WILL BE ABOVE NORMAL...WHILE NEXT
WEEK WILL BE CLOSER TO NORMAL FOR THIS TIME OF YEAR. HIGHS ON
TUESDAY APPEAR TO BE THE ONE EXCEPTION...WITH TEMPERATURES MORE
LIKELY TO BE SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z SATURDAY MORNING)
ISSUED AT 550 AM CDT FRI MAY 17 2013
VFR CONDITIONS WILL PREVAIL AT KGRI FOR THE NEXT 24 HOURS. EXPECT
THE MID LEVEL CLOUD DECK COVERING MUCH OF NEBRASKA EARLY THIS
MORNING TO RAPIDLY SCATTER OUT OVER THE NEXT COUPLE OF HOURS AS
SHORT WAVE RIDGING TRANSITIONS ACROSS THE PLAINS.
OTHERWISE...EXPECT WINDS TO BE THE PRIMARY FOCUS...WITH THE
PRESSURE GRADIENT ANTICIPATED TO TIGHTEN UP THE BY EARLY AFTERNOON
AS A TROUGH OF LOW PRESSURE DEVELOPS ON THE LEE SIDE OF THE
ROCKIES...SO WENT AHEAD AND INCLUDED WIND GUSTS TO 24KTS AFT
17/18Z.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...SAR
LONG TERM...GUERRERO
AVIATION...SAR
AREA FORECAST DISCUSSION
NWS HASTINGS NE
435 AM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT FRI MAY 17 2013
ANOTHER SEASONABLY WARM AFTERNOON IS EXPECTED ACROSS THE REGION AS
WEAK UPPER LEVEL RIDING WORKS ITS WAY IN FROM THE WEST. EARLY THIS
MORNING...SOME SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED TO THE
WEST OF THE LOCAL AREA...LIKELY A FACTOR OF THE LOW LEVEL JET
PROVIDING JUST ENOUGH FORCING ACROSS WESTERN KANSAS EARLY THIS
MORNING TO SPARK SOME CONVECTION. HOWEVER WITH THIS ACTIVITY SHOWING
SIGNS OF DIMINISHING AND LITTLE INSTABILITY TO KEEP IT GOING AS IT
APPROACHES THE LOCAL AREA...DECIDED TO JUST ADD A SLIGHT CHANCE OF
SPRINKLES ACROSS THE WESTERN FRINGES OF OUR FORECAST AREA THROUGH 8
AM TO ACCOUNT FOR ANY REMNANTS OF THIS CONVECTION AS IT WORKS EAST.
OTHERWISE...HAVE SEEN SOME PATCHY FOG DEVELOP ACROSS AROUND LXN AND
ODX EARLY THIS MORNING AS TEMPERATURES HAVE FALLEN TO REACH THE
DEWPOINTS AT THESE LOCATIONS THE PAST COUPLE OF HOURS...AND THINK
SOME FURTHER DEVELOPMENT WILL BE POSSIBLE OVER THE NEXT FEW
HOURS...GENERALLY WEST OF HIGHWAY 281. HRRR AND SREF HAVE BOTH
BACKED OFF ON POTENTIAL FOG DEVELOPMENT FOR THIS MORNING...AND
EXPECT ANY FOG THAT DOES MANAGE TO DEVELOP TO BE FAIRLY PATCHY AND
SHORT LIVED...AND CORRESPONDINGLY TRIMMED BACK COVERAGE FROM PREVIOUS
FORECAST.
FOR THIS AFTERNOON...EXPECT TEMPERATURES TO CLIMB BACK INTO THE MID
AND UPPER 80S ACROSS THE ENTIRE FORECAST AREA AS PARTLY CLOUDY TO
MOSTLY SUNNY SKIES WILL WORK THEIR WAY IN ACROSS THE REGION AS THE
RIDGE TRANSITIONS EASTWARD. ADDITIONALLY...WITH THE RIDGE AXIS
MOVING OVERHEAD...850MB TEMPS WILL CLIMB A COUPLE OF DEGREES FROM
YESTERDAYS VALUES...FURTHER AIDING IN A SEASONABLY WARM AFTERNOON.
AT THE SURFACE...EXPECT A SURFACE TROUGH TO DEVELOP ON THE LEE SIDE
OF THE ROCKIES BY EARLY AFTERNOON...AND THIS SHOULD HELP INCREASE
THE PRESSURE GRADIENT JUST ENOUGH TO RESULT IN BREEZY SOUTHERLY
WINDS...GENERALLY 15 TO 25 MPH IN MOST SPOTS.
FOR TONIGHT...SOME OF THE GUIDANCE IS ATTEMPTING TO DEVELOP SOME
CONVECTION ACROSS THE HIGH PLAINS AND TRANSITION IT EASTWARD AROUND
SUNSET. WHILE THERE WILL BE PLENTY OF INSTABILITY TO JUSTIFY
CONVECTION TO OUR WEST...A DECENT CAP IS FORECAST AROUND 800 MB
WITH LITTLE IN THE WAY OF FORCING TO JUSTIFY MUCH CONVECTION
ACROSS THE LOCAL AREA. EVEN SO...WITH 00Z WRF BEING THE MOST
AGGRESSIVE TRANSLATING SOME OF THE REMNANTS OF THE HIGH PLAINS
CONVECTION ACROSS THE LOCAL AREA DURING THE EVENING HOURS...FELT
JUSTIFIED ADDING A FEW SPRINKLES TO THE NORTHWESTERN QUADRANT OF THE
LOCAL AREA JUST IN CASE A FEW SHOWERS ARE ABLE TO MAINTAIN
THEMSELVES AS THEY TRACK EAST.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 408 AM CDT FRI MAY 17 2013
THUNDERSTORM CHANCES THIS WEEKEND WILL BE THE PRIMARY FOCUS OF
LONG TERM. IT SHOULD BE NOTED THAT THERE ARE CHANCES FOR
PRECIPITATION NEARLY EVERYDAY OVER THE LONG TERM...BUT THE CHANCE
FOR SEVERE THUNDERSTORMS APPEARS TO BE BEST ON SATURDAY AT THE MOMENT.
AN UPPER LEVEL TROUGH WILL BEGIN TRANSITIONING OVER THE WEST COAST
TODAY AND WILL EVENTUALLY MOVE EASTWARD INTO THE INTERMOUNTAIN WEST
ON SATURDAY. AT THE SURFACE ON SATURDAY...A LEE LOW WILL FORM AHEAD
OF THE UPPER LEVEL TROUGH...AND A COLD FRONT WILL DRAPE INTO
NEBRASKA WHICH SHOULD HELP TO INITIATE THUNDERSTORMS ACROSS THE
OUTLOOK AREA LATER IN THE AFTERNOON. THERE WILL BE A STRONG
CAPPING INVERSION IN PLACE AT THE MID-LEVELS...SO THIS WILL NEED
TO ERODE/BREAK BEFORE ANY CONVECTION CAN INITIALIZE. A FEW THINGS
SHOULD HELP TO GET STORMS INITIATED LATER IN THE AFTERNOON THOUGH.
FOR ONE...THE ADVECTION OF STEEPER LAPSE RATES IN THE MID-LEVELS
WILL HELP WEAKEN THIS CAP. SECONDLY...THE COLD FRONT PROGGED TO
SLIDE OVER THE REGION SHOULD SERVE AS A GOOD LIFTING MECHANISM TO
HELP GET CONVECTION STARTED IN THE AFTERNOON. LASTLY...MODERATE TO
STRONG INSTABILITY ON THE ORDER OF 3000-4000 J/KG OF MLCAPE IS
FORECAST BY 00Z SUNDAY...SO ANY STORMS THAT DO FORM WILL HAVE THE
ABILITY TO BECOME STRONG TO SEVERE. AS THE EVENT UNFOLDS LATER
INTO THE EVENING...THE FORMATION ON AN MCS IS DEFINITELY POSSIBLY
AND SHOULD POSE A PRIMARY THREAT OF DAMAGING WINDS. HAIL WILL BE
THE PRIMARY THREAT EARLY IN THE EVENT...ESPECIALLY THE MORE
ISOLATED/DISCRETE CELLS WITH STRONG UPDRAFTS. ITS ALSO WORTH
NOTING THE NAM...GFS...AND EC ALL SHOW STRONG 0-1 KM BULK SHEAR ON
THE ORDER OF 25 TO 30 KTS. DEEP LAYER SHEAR WAS NOT AS IMPRESSIVE
BUT STILL HAD VALUES AROUND 35 KTS. THE SHEAR ENVIRONMENT COUPLED
WITH STRONG INSTABILITY WOULD SUGGEST SUPERCELLS COULD FORM AND
WITH ANY SUPERCELL...THERE WILL ALSO BE A TORNADO THREAT.
MOVING INTO SUNDAY...THUNDERSTORMS WILL LIKELY CONTINUE MOVING
EASTWARD ACROSS THE OUTLOOK AREA. THE SEVERE THREAT WILL BE OVERALL
LIMITED...BUT OUR EASTERN COUNTIES COULD POTENTIALLY SEE THE SEVERE
THREAT CONTINUE INTO THE AFTERNOON HOURS ON SUNDAY...PRIMARILY EAST
OF HIGHWAY 281. NEXT WEEK WILL HAVE POPS ANYWHERE FROM 10 TO 30
PERCENT NEARLY EVERYDAY. THESE POPS ARE ROOTED IN THE TROUGH
CURRENTLY OVER THE WEST COAST WHICH IS FORECAST TO MEANDER AROUND
THE GREAT PLAINS NEXT WEEK. THE BIGGEST DISADVANTAGE IN THE LONG
TERM IS THE LACK OF CONSISTENCY AND AGREEMENT BETWEEN THE MODELS.
THROUGH THE WEEKEND...TEMPERATURES WILL BE ABOVE NORMAL...WHILE NEXT
WEEK WILL BE CLOSER TO NORMAL FOR THIS TIME OF YEAR. HIGHS ON
TUESDAY APPEAR TO BE THE ONE EXCEPTION...WITH TEMPERATURES MORE
LIKELY TO BE SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1220 AM CDT FRI MAY 17 2013
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KGRI FOR THE NEXT 24
HOURS. EXPECT THE MID LEVEL CLOUD DECK COVERING MUCH OF NEBRASKA
THIS EVENING...TO GRADUALLY CLEAR OVERNIGHT AS A SHORT WAVE RIDE
TRANSITIONS ACROSS THE PLAINS. THIS SHOULD PUT AN END TO ANY
REMAINING SHOWER ACTIVITY AS WELL. WHILE WINDS WILL HAVE A SLIGHT
SOUTHEASTERLY COMPONENT AND DEWPOINTS WILL REMAIN ELEVATED
OVERNIGHT...MAY SEE SOME PATCHY FOG DEVELOPMENT AS INDICATED BY
SOME OF GUIDANCE...BUT CONFIDENCE OF THIS IS LOW...AND DID NOT
INCLUDE IN TAF. OTHERWISE...EXPECT A SURFACE TROUGH OF LOW
PRESSURE TO DEVELOP TO THE WEST TOMORROW AFTERNOON...AND THIS
SHOULD HELP TO TIGHTEN UP THE PRESSURE GRADIENT...SO WENT AHEAD
AND INCLUDED WIND GUSTS INTO THE LOWER 20S TOMORROW AFTERNOON.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...SAR
LONG TERM...GUERRERO
AVIATION...SAR
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
258 AM EDT FRI MAY 17 2013
.SYNOPSIS...
FAIR WEATHER WILL PERSIST INTO SATURDAY, WITH SEASONABLE DAYTIME
TEMPERATURES AND COOL OVERNIGHTS. A WEAK FRONT MAY BRING ISOLATED
SHOWERS TO THE REGION ON SUNDAY, THOUGH MOST AREAS WILL REMAIN
DRY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1015 PM UPDATE...
WEAK SECONDARY FRONT CONTINUES TO SINK SOUTH ACROSS THE REGION
THIS EVENING WITH UPSTREAM OBSERVATIONS AT ART AND GTB CLEARLY
SHOWING A WINDSHIFT TO THE NORTH. IR SATELLITE IMAGERY A FAIRLY
RAPID DECREASE IN CLOUDS ALONG THIS FEATURE WITH LOSS OF DAYTIME
HEATING AND SKY GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. SOME CONCERN
STILL LINGERS FOR PATCHY FROST ACROSS THE CHEMUNG BASIN AFTER 06Z
BUT OVERALL CONFIDENCE REMAINS MARGINAL AS TEMPS HAVE BEEN SLOW TO
COOL THIS EVENING WITH FRONT STILL TO THE NORTH THIS HR. SINCE WE
CANNOT RULE IT OUT HOWEVER...A PATCHY FROST MENTION HAS BEEN
MAINTAINED FOR NOW. NO OTHER ADJUSTMENTS NEEDED AT THIS TIME.
715 PM UPDATE...
FCST IN GREAT SHAPE THIS EVENING...NO SIGNIFICANT CHANGES NEEDED
AT THE PRESENT TIME. VIS SATELLITE SHOTS STILL SHOWING A FAIRLY
WELL DEFINED AND NARROW CU FIELD ALONG A SOUTHWARD SAGGING SECONDARY
COLD FRONT WHICH NOW STRETCHES FROM NEAR WATERTOWN/FT. DRUM...WEST
THROUGH KINGSTON ONTARIO. FEATURE WILL CONTINUE DIVING SOUTH
THROUGH THE FCST AREA THIS EVENING BEFORE CLEARING THE CWA SHORTLY
AFTER 06Z. ATTENTION THROUGH THE OVERNIGHT WILL REMAIN FOCUSED ON
POSSIBLE FROST POTENTIAL ACROSS THE CHEMUNG RVR VLY. WILL CONTINUE
TO MONITOR TRENDS HOWEVER LATEST MODEL GUIDANCE CONTINUES TO
SUGGEST FAIRLY DRY LOW-LEVEL CONDITIONS WHICH SHOULD KEEP FROST
DEVELOPMENT RATHER ISOLATED AT BEST.
3 PM UPDATE...
JUST A FEW FAIR WEATHER CUMULUS AT 8-10 KFT AGL THIS AFTERNOON
WHICH WILL QUICKLY DISSIPATE. AS EXPECTED...INVERTED-V PROFILE HAS
MIXED DOWN FAIRLY GUSTY WINDS ALONG WITH VERY DRY AIR AND THUS
A MAXIMIZED DIURNAL RANGE. WIDESPREAD 70S WITH SOME LOCATIONS SUCH
AS ELMIRA EVEN TOUCHING 80 DEGREES FOR TEMPERATURES...AND HUMIDITY
VALUES AREAWIDE HAVE MANAGED MAINLY 20S PERCENT RANGE.
SECONDARY COLD FRONT WILL DIP ACROSS THE AREA TONIGHT...AND WITH
SUCH LIMITED MOISTURE...NO PRECIPITATION EXPECTED WHATSOEVER.
LOSS OF DIURNAL HEATING WILL ERODE MUCH OF THE CLOUD COVER
CURRENTLY BEHIND THE FRONT IN CENTRAL ONTARIO AND QUEBEC.
HOWEVER...WRFARW AND RUC SOUNDINGS SHOW THAT BAND OF MOISTURE 4-5
KFT AGL WILL ADVECT IN IMMEDIATELY ALONG THE FRONT ITSELF. SKY
GRIDS THUS REFLECT SOME CLOUDS DROPPING ACROSS THE NORTHERN TO
CENTRAL PART OF THE AREA OVERNIGHT...BEFORE MIXING OUT IN DRY AIR
FRIDAY MORNING.
EXPECTING MAINLY 40S FOR LOWS TONIGHT...BUT FAIR AMOUNT OF
RADIATIONAL COOLING WILL LEAD THE TYPICAL COLDER DRAINAGE-PRONE
SPOTS GETTING INTO THE 30S. PATCHY FROST HAS BEEN ADDED TO A
COUPLE SPOTS IN THE WEATHER GRIDS IN CENTRAL SOUTHERN TIER OF NY
TO BRADFORD COUNTY PA...BUT NOT EXPECTING ENOUGH TO WARRANT FROST
ADVISORY. THE EVENING SHIFT WILL MONITOR THIS CLOSELY IN CASE
EXPECTATIONS SHOULD CHANGE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
315 PM UPDATE...
HIGH PRESSURE IN CHARGE FRIDAY INTO FRIDAY NIGHT WITH DRY WEATHER
AND TEMPERATURES RIGHT AROUND CLIMATOLOGY. BAROCLINIC ZONE SETS UP
JUST SOUTH AND SOUTHWEST OF OUR VICINITY OVER THE WEEKEND. WHAT
HAS BECOME CLEARER IS THAT CLOUDS WILL DEVELOP AND THICKEN
COURTESY OF MOISTENING BAROCLINIC LIFT...ESPECIALLY CENTRAL TO
SOUTHERN ZONES. HOWEVER...WITH DRY AIR IN THE LOW LEVELS AND FAIRLY
WEAK WAVES ALOFT...PRECIPITATION CHANCES ARE MUCH MORE IFFY.
ALSO...AS HIGH PRESSURE SITUATES OFFSHORE INTO
SUNDAY...STABILIZING COOL ONSHORE SOUTHEAST FLOW WILL DIP
TEMPERATURES ESPECIALLY FROM TWIN TIERS SOUTHWARD. EVER SLOW
SLIGHT YET VERY ELEVATED INSTABILITY ALSO IS SUGGESTED BY THE
SOUNDINGS AT LEAST FOR LATE SATURDAY INTO SATURDAY NIGHT.
OVERALL NOT VERY BULLISH ON RAIN CHANCES BUT HAVE TO RESPECT
PRESENCE OF BAROCLINIC ZONE AND MOISTURE...WHICH SOMETIMES YIELDS
SURPRISES THAT MODELS CAN STRUGGLE WITH. FOR NOW...WENT WITH
SLIGHT TO LOW CHANCE POPS MAINLY WESTERN/SOUTHERN ZONES LATE
SATURDAY...THEN SPREADING OVER REMAINDER OF THE AREA SATURDAY
NIGHT INTO SUNDAY.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD
INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST
INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS.
TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER
LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE
NORTHEAST.
AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW
ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL
PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT
CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA.
FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS
FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE
WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH
TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED
NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL
AS UPPER LEVEL TROF RESIDES OVER REGION.
TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A
RETURN TO MORE SEASONAL TEMPS BY THURSDAY.
&&
.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
NW FLOW OF DRY AIR WILL CONT THRU THE TAF PD KEEPING VFR CONDS FOR
ALL SITES. LGT WINDS THIS MRNG WILL BECOME NW ARND 10 KTS
TODAY...BUT WILL NOT BE AS GUSTY AS THU. THE WILL BECOME LGT ONCE
AGAIN AFTN DARK FRI AS WE LOSE MIXING.
OUTLOOK...
SATURDAY THROUGH TUESDAY...PRIMARILY VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP
SHORT TERM...DJP
LONG TERM...RRM
AVIATION...DGM/JAB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
159 AM EDT FRI MAY 17 2013
.SYNOPSIS...
DRY CONDITIONS WILL PERSIST THROUGH AT LEAST SATURDAY MORNING.
CLOUDS WILL DEVELOP OVER THE WEEKEND AS A FRONTAL ZONE SETS UP
NEAR OUR VICINITY. SOME AREAS MAY GET A FEW LIGHT SHOWERS LATE
SATURDAY INTO SUNDAY...WITH BEST CHANCES IN NORTHEAST
PENNSYLVANIA.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1015 PM UPDATE...
WEAK SECONDARY FRONT CONTINUES TO SINK SOUTH ACROSS THE REGION
THIS EVENING WITH UPSTREAM OBSERVATIONS AT ART AND GTB CLEARLY
SHOWING A WINDSHIFT TO THE NORTH. IR SATELLITE IMAGERY A FAIRLY
RAPID DECREASE IN CLOUDS ALONG THIS FEATURE WITH LOSS OF DAYTIME
HEATING AND SKY GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. SOME CONCERN
STILL LINGERS FOR PATCHY FROST ACROSS THE CHEMUNG BASIN AFTER 06Z
BUT OVERALL CONFIDENCE REMAINS MARGINAL AS TEMPS HAVE BEEN SLOW TO
COOL THIS EVENING WITH FRONT STILL TO THE NORTH THIS HR. SINCE WE
CANNOT RULE IT OUT HOWEVER...A PATCHY FROST MENTION HAS BEEN
MAINTAINED FOR NOW. NO OTHER ADJUSTMENTS NEEDED AT THIS TIME.
715 PM UPDATE...
FCST IN GREAT SHAPE THIS EVENING...NO SIGNIFICANT CHANGES NEEDED
AT THE PRESENT TIME. VIS SATELLITE SHOTS STILL SHOWING A FAIRLY
WELL DEFINED AND NARROW CU FIELD ALONG A SOUTHWARD SAGGING SECONDARY
COLD FRONT WHICH NOW STRETCHES FROM NEAR WATERTOWN/FT. DRUM...WEST
THROUGH KINGSTON ONTARIO. FEATURE WILL CONTINUE DIVING SOUTH
THROUGH THE FCST AREA THIS EVENING BEFORE CLEARING THE CWA SHORTLY
AFTER 06Z. ATTENTION THROUGH THE OVERNIGHT WILL REMAIN FOCUSED ON
POSSIBLE FROST POTENTIAL ACROSS THE CHEMUNG RVR VLY. WILL CONTINUE
TO MONITOR TRENDS HOWEVER LATEST MODEL GUIDANCE CONTINUES TO
SUGGEST FAIRLY DRY LOW-LEVEL CONDITIONS WHICH SHOULD KEEP FROST
DEVELOPMENT RATHER ISOLATED AT BEST.
3 PM UPDATE...
JUST A FEW FAIR WEATHER CUMULUS AT 8-10 KFT AGL THIS AFTERNOON
WHICH WILL QUICKLY DISSIPATE. AS EXPECTED...INVERTED-V PROFILE HAS
MIXED DOWN FAIRLY GUSTY WINDS ALONG WITH VERY DRY AIR AND THUS
A MAXIMIZED DIURNAL RANGE. WIDESPREAD 70S WITH SOME LOCATIONS SUCH
AS ELMIRA EVEN TOUCHING 80 DEGREES FOR TEMPERATURES...AND HUMIDITY
VALUES AREAWIDE HAVE MANAGED MAINLY 20S PERCENT RANGE.
SECONDARY COLD FRONT WILL DIP ACROSS THE AREA TONIGHT...AND WITH
SUCH LIMITED MOISTURE...NO PRECIPITATION EXPECTED WHATSOEVER.
LOSS OF DIURNAL HEATING WILL ERODE MUCH OF THE CLOUD COVER
CURRENTLY BEHIND THE FRONT IN CENTRAL ONTARIO AND QUEBEC.
HOWEVER...WRFARW AND RUC SOUNDINGS SHOW THAT BAND OF MOISTURE 4-5
KFT AGL WILL ADVECT IN IMMEDIATELY ALONG THE FRONT ITSELF. SKY
GRIDS THUS REFLECT SOME CLOUDS DROPPING ACROSS THE NORTHERN TO
CENTRAL PART OF THE AREA OVERNIGHT...BEFORE MIXING OUT IN DRY AIR
FRIDAY MORNING.
EXPECTING MAINLY 40S FOR LOWS TONIGHT...BUT FAIR AMOUNT OF
RADIATIONAL COOLING WILL LEAD THE TYPICAL COLDER DRAINAGE-PRONE
SPOTS GETTING INTO THE 30S. PATCHY FROST HAS BEEN ADDED TO A
COUPLE SPOTS IN THE WEATHER GRIDS IN CENTRAL SOUTHERN TIER OF NY
TO BRADFORD COUNTY PA...BUT NOT EXPECTING ENOUGH TO WARRANT FROST
ADVISORY. THE EVENING SHIFT WILL MONITOR THIS CLOSELY IN CASE
EXPECTATIONS SHOULD CHANGE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/...
315 PM UPDATE...
HIGH PRESSURE IN CHARGE FRIDAY INTO FRIDAY NIGHT WITH DRY WEATHER
AND TEMPERATURES RIGHT AROUND CLIMATOLOGY. BAROCLINIC ZONE SETS UP
JUST SOUTH AND SOUTHWEST OF OUR VICINITY OVER THE WEEKEND. WHAT
HAS BECOME CLEARER IS THAT CLOUDS WILL DEVELOP AND THICKEN
COURTESY OF MOISTENING BAROCLINIC LIFT...ESPECIALLY CENTRAL TO
SOUTHERN ZONES. HOWEVER...WITH DRY AIR IN THE LOW LEVELS AND FAIRLY
WEAK WAVES ALOFT...PRECIPITATION CHANCES ARE MUCH MORE IFFY.
ALSO...AS HIGH PRESSURE SITUATES OFFSHORE INTO
SUNDAY...STABILIZING COOL ONSHORE SOUTHEAST FLOW WILL DIP
TEMPERATURES ESPECIALLY FROM TWIN TIERS SOUTHWARD. EVER SLOW
SLIGHT YET VERY ELEVATED INSTABILITY ALSO IS SUGGESTED BY THE
SOUNDINGS AT LEAST FOR LATE SATURDAY INTO SATURDAY NIGHT.
OVERALL NOT VERY BULLISH ON RAIN CHANCES BUT HAVE TO RESPECT
PRESENCE OF BAROCLINIC ZONE AND MOISTURE...WHICH SOMETIMES YIELDS
SURPRISES THAT MODELS CAN STRUGGLE WITH. FOR NOW...WENT WITH
SLIGHT TO LOW CHANCE POPS MAINLY WESTERN/SOUTHERN ZONES LATE
SATURDAY...THEN SPREADING OVER REMAINDER OF THE AREA SATURDAY
NIGHT INTO SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD
INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST
INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS.
TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER
LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE
NORTHEAST.
AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW
ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL
PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT
CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA.
FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS
FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE
WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH
TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED
NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL
AS UPPER LEVEL TROF RESIDES OVER REGION.
TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A
RETURN TO MORE SEASONAL TEMPS BY THURSDAY.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
NW FLOW OF DRY AIR WILL CONT THRU THE TAF PD KEEPING VFR CONDS FOR
ALL SITES. LGT WINDS THIS MRNG WILL BECOME NW ARND 10 KTS
TODAY...BUT WILL NOT BE AS GUSTY AS THU. THE WILL BECOME LGT ONCE
AGAIN AFTN DARK FRI AS WE LOSE MIXING.
OUTLOOK...
SATURDAY THROUGH TUESDAY...PRIMARILY VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MDP
NEAR TERM...CMG/MDP
SHORT TERM...MDP
LONG TERM...RRM
AVIATION...DGM/JAB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 PM EDT FRI MAY 17 2013
.SYNOPSIS...
A COLD FRONT OVER CENTRAL VIRGINIA WILL SAG SOUTH AND BE LOCATED
NEAR THE NORTH CAROLINA BORDER BY LATE TONIGHT. UPPER LEVEL LOW
PRESSURE WILL CONTINUE TO MOVE EAST AND HAVE A MAJOR INFLUENCE ON
THE WEATHER OF THE REGION OVER THE WEEKEND. ATLANTIC HIGH PRESSURE
GRADUALLY BUILDS INTO THE CAROLINAS EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 255 PM FRIDAY...
THE LATEST SURFACE ANALYSIS SHOWED A SURFACE FRONT ACROSS NORTHERN
INDIANA AND OHIO...THEN BENDING SOUTHEAST ACROSS SOUTHWEST
PENNSYLVANIA TOWARD FAR NORTHEAST NORTH CAROLINA. ALONG AND JUST
AHEAD OF THE FRONT OVER NORTHEAST NORTH CAROLINA...INCLUDING THE
COASTAL PLAIN...INSTABILITY WAS HIGHEST WITH MIXED-LAYER CAPE ON THE
ORDER OF 500J/KG ON THE LATEST SPC MESOANALYSIS. GIVEN THE LIGHT
WIND FIELD CONVERGENCE WAS MEAGER...AND WHILE SURFACE DEW POINTS HAD
YET TO FALL AS FAR AS THE RAP FORECAST...THEY STILL HAVE FALLEN
SOLIDLY INTO THE 50S OVER MOST PARTS OF CENTRAL NORTH CAROLINA. THIS
HAS MADE IT DIFFICULT FOR ANY DEEP CONVECTION TO DEVELOP.
GIVEN THE DIFFERENCES IN THE MOISTURE GUIDANCE AS WELL AS THE OUTPUT
OF THE CONVECTION-ALLOWING MODELS...AND CONSIDERING THE NAM APPEARS
SO OUT OF TOLERANCE WITH ITS FORECAST SURFACE DEW POINTS...HAVE
LEANED TOWARD A CONSENSUS OF THE RAP AND GFS OVERNIGHT. THIS WOULD
SUPPORT THE BETTER CHANCES OF ANY SHOWERS OR THUNDERSTORMS OVERNIGHT
ALONG AND AHEAD OF THE SURFACE FRONT...MAINLY ALONG AND NORTH OF A
LINE FROM ABOUT KTDF TO KRWI. THIS IS WHERE THE RAP SHOWS LOW-LEVEL
MOISTURE POOLING AROUND AND AFTER 00Z...SUPPORTED MOST BY THE LOCAL
RALIEGH WRF REFLECTIVITY FORECAST. IN THE RELATIVELY MORE STABLE AIR
OVER THE SOUTHWEST PIEDMONT IN PARTICULAR...WILL KEEP CONDITIONS DRY
UNTIL THE OVERNIGHT HOURS...AND THEN ONLY NOTE A SLIGHT CHANCE OF A
SHOWER THERE AND ELSEWHERE ACROSS CENTRAL NORTH CAROLINA. IT SHOULD
BE NOTED THAT SOME OF THE GUIDANCE POPS...PARTICULARLY FROM THE
NAM...ARE QUITE HIGH OVERNIGHT...BUT THE NAM ALSO FORECASTS SURFACE
DEW POINTS GETTING NEAR 70 OVER PARTS OF THE NORTHWEST PIEDMONT BY
21Z...WHICH CURRENTLY SEEMS UNLIKELY. UNDER A CONTINUING MID-LEVEL
RIDGE AHEAD OF THE TROUGH MOVING EAST...WILL ANTICIPATE A DIURNAL
REDUCTION IN CHANCES FOR PRECIPITATION FOR ONE MORE NIGHT. OVERNIGHT
LOWS IN THE LOWER TO MID 60S.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 255 PM FRIDAY...
THE TROUGH ALOFT GRADUALLY MOVES INTO CENTRAL NORTH CAROLINA
SATURDAY AND SATURDAY NIGHT. WHILE DIFFERENCES CONTINUE WITH THE
DETAILS IN THE GUIDANCE...INCLUDING VARIOUS WRF OUTPUT...ON A LARGE
SCALE...MEAN RH INCREASES TO A MAXIMUM DURING THE PERIOD LATE
SATURDAY AFTERNOON IN THE NORTHWEST PIEDMONT...AND TO ABOUT U.S. 1
OR SO SATURDAY NIGHT. THE BEST LIFT IS NORTHWEST CLOSER TO THE UPPER
TROUGH...850MB THETA-E IS GREATEST IN CONJUNCTION WITH THE MEAN
RELATIVE HUMIDITY...AND BY LATE SATURDAY AFTERNOON AND SATURDAY
NIGHT...THE 850MB FLOW FROM THE SOUTHWEST INCREASES TO AROUND 25KT
FOCUSED OVER AND NEAR THE WESTERN PIEDMONT. BUFR SOUNDINGS
ESPECIALLY FROM THE GFS SHOW GREATER MOISTURE AND INSTABILITY WEST
COMPARED TO EAST IN CENTRAL NORTH CAROLINA. AS A RESULT...INSTEAD OF
TRYING TO INTERPRET THE VARIETY OF WRF TRENDS...HAVE FOLLOWED A
PRECIPITATION FORECAST LEANING MORE TOWARD LARGE-SCALE FEATURES.
THIS RESULTS IN MOSTLY CHANCE POPS FOR SATURDAY...BECOMING LIKELY IN
THE IMMEDIATE TRIAD BY LATE IN THE DAY AND SPREADING LIKELY POPS TO
AROUND U.S. 1 BY OVERNIGHT SATURDAY CLOSER TO 850MB LOW PRESSURE.
THE LEAST CHANCES WILL BE TOWARD KGSB AND KCTZ...WHERE OVERALL
MOISTURE AND LIFT ARE LEAST...CLOSER ALSO TO THE 850MB RIDGE JUST
OFFSHORE. THE GFS HAS FAIRLY ROBUST PRECIPITATION AMOUNTS IN THE
TRIAD OVERNIGHT SATURDAY AND THIS WILL HAVE TO BE WATCHED...BUT FOR
NOW WILL FORECAST AVERAGE PRECIPITATION AMOUNTS THERE AROUND 0.75
INCH FROM LATE SATURDAY AFTERNOON THROUGH SATURDAY NIGHT. HIGHS
SATURDAY NEAR 80 NORTHWEST TO THE UPPER 80S SOUTHEAST...WITH
OVERNIGHT LOWS SATURDAY NIGHT IN THE MID 60S.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 255 PM FRIDAY...
SUNDAY THROUGH MONDAY NIGHT: CONFIDENCE IN AN UNSETTLED WEATHER
PATTERN IS HIGH THROUGH MONDAY NIGHT...HOWEVER THE TIMING...COVERAGE
AND INTENSITY OF PRECIPITATION IS STILL AN ISSUE. AN UPPER LEVEL
SHORTWAVE DISTURBANCE ALONG THE RIDGE AXIS MOVING OVER CENTRAL NC ON
SUNDAY AND MONDAY WILL AID IN THE DEVELOPMENT OF SHOWERS AND STORMS
THROUGH THE PERIOD. AT H850 A TROUGH WILL EXTEND EAST FROM THE
PARENT LOW OVER THE MIDWEST AND INTO TN AND THE CAROLINAS THROUGH
MONDAY...WITH RIDGING TO THE NORTH FROM AN OFFSHORE HIGH. ALTHOUGH
THERE ARE STILL SOME DIFFERENCES BETWEEN THE MODELS AND FROM RUN TO
RUN...THE GFS AND ECMWF HAVE COME INTO BETTER AGREEMENT WITH RESPECT
TO THE STRENGTH AND CHARACTER OF THE SHORTWAVE LOW...THUS WILL
CONTINUE A BLEND OF THE TWO. AT THE SURFACE...THE GFS CONTINUES TO
SHOW A LOW DEVELOPING IN THE LEE OF THE ROCKIES THIS WEEKEND AND
DEEPENING AS IT MIGRATES SLOWLY EAST INTO EASTERN SD...EXTENDING SSE
THROUGH CENTRAL OK/TX...AND A TROUGH AXIS EXTENDING EAST INTO THE
MID ATLANTIC STATES. WARM MOIST SW FLOW OFF THE GULF WILL KEEP PWAT
VALUES IN THE 1.5 TO 2.0 INCH RANGE THROUGH MONDAY NIGHT FUELING THE
POTENTIAL FOR SOME SIGNIFICANT STORM TOTAL RAINFALL AMOUNTS GIVEN
THE WEAK STEERING FLOW EXPECTED. MODEL GENERATED MLCAPE IS OF THE
TALL AND SKINNY VARIETY...WITH VALUES OF 1000-1500 J/KG SUNDAY AND
MONDAY. COMBINED WITH 0-6 KM BULK SHEAR VALUES OF MAINLY 10-20
KTS...EXPECT CONVECTIVE MODE TO BE MAINLY DISORGANIZED PULSE TYPE
STORMS...ALTHOUGH AN ISOLATED STRONG STORM CANNOT BE RULED OUT. THE
BIGGER THREAT CONTINUES TO BE FROM POTENTIALLY HEAVY RAINFALL...
ESPECIALLY SUNDAY NIGHT AND MONDAY. GIVEN THE UNCERTAINTY REGARDING
PRECIP AMOUNTS...HAVE DECREASED STORM TOTAL RAINFALL TOTALS FROM THE
PREVIOUS FORECAST...HOWEVER WIDESPREAD 1-2 INCHES IS STILL LIKELY
THROUGH MONDAY NIGHT. HIGH TEMPERATURES THROUGH THIS PERIOD CONTINUE
TO BE DEPENDENT ON CLOUD COVER AND PRECIPITATION. FOR NOW...EXPECT
HIGHS IN THE UPPER 70S NORTH AND LOW TO MID 80S ACROSS THE EAST AND
SOUTH. OVERNIGHT LOWS WILL STAY MAINLY IN THE MID 60S.
TUESDAY THROUGH FRIDAY: AS THE SHORTWAVE MOVES NORTHEAST AWAY FROM
THE AREA ON TUESDAY...HIGH PRESSURE WILL BUILD INTO THE CAROLINAS
FROM THE ESE...WITH RETURN FLOW OFF THE ATLANTIC AND A SLIGHT
DECREASE IN FORECAST PWAT VALUES. DRY AIR ADVECTING IN AT THE MID
LEVELS SHOULD DECREASE RAINFALL CHANCES THROUGH WEDNESDAY ALTHOUGH
THE POSSIBILITY OF AN AFTERNOON SHOWER EXISTS. A MIDWEST LOW WILL
MOVE EAST TOWARD THE MID ATLANTIC DURING THIS TIME AND THE TROUGH
BECOMES ORIENTED MORE SW TO NE...WITH INCREASING PRECIPITATION
CHANCES ON THURSDAY AND FRIDAY. GIVEN THE DIFFERENCES BETWEEN THE
MODELS...THERE IS A GOOD DEAL OF UNCERTAINTY WITH RESPECT TO
PRECIPITATION MOVING AHEAD OF THE SYSTEM. FOR NOW WILL CARRY SLIGHT
CHANCES FOR SHOWERS AND STORMS DURING THE AFTERNOON HOURS THURSDAY
AND FRIDAY...WITH A DRY FORECAST FOR THE OVERNIGHT HOURS. HIGH TEMPS
TUESDAY AND WEDNESDAY IN THE MID TO UPPER 80S...DECREASING AGAIN
THROUGH FRIDAY...UPPER 70S TO LOW 80S. OVERNIGHT LOWS REMAIN STEADY
IN THE MID TO UPPER 60S.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 255 PM FRIDAY...
MAINLY VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE 18Z VALID
TAF PERIOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS. THE BEST CHANCE
OF A SHOWER OR THUNDERSTORM OVERNIGHT APPEARS TO BE TOWARD THE TRIAD
AND KRWI...POSSIBLY AS FAR SOUTH AS KRDU...WITH LESSER POTENTIAL
TOWARD KFAY. A PERIOD OF MVFR FOG IS POSSIBLE AT ALL TAF SITES LATE
TONIGHT INTO EARLY SATURDAY IN AN AIR MASS THAT GRADUALLY MOISTENS
AGAIN OVERNIGHT. SOME OF THE GUIDANCE SUGGESTS A SMALL POTENTIAL FOR
LOW CLOUDS AT KINT...KGSO...AND KRWI...BUT THE SREF MODEL
PROBABILITIES OF CLOUDS BELOW 1000FT ARE HIGHEST JUST NORTHEAST OF
KRWI TOWARD KIXA...KASJ...AND KEDE AND WERE ONLY NOTED WITH FEW IN
THE TAFS LATE TONIGHT INTO EARLY SATURDAY IN CENTRAL NORTH CAROLINA.
BEYOND THE 18Z VALID TAF PERIOD...CHANCES FOR SHOWERS AND
THUNDERSTORMS GRADUALLY INCREASE...BECOMING LIKELY IN THE TRIAD BY
LATE SATURDAY AFTERNOON AND EXTENDING AT LEAST TO KRDU BY SATURDAY
NIGHT AS AN UPPER-LEVEL TROUGH MOVES EAST. ALONG WITH THE SUB-VFR
CONDITIONS THAT THE SHOWERS AND STORMS WOULD BRING...THERE IS A GOOD
CHANCE OF IFR CONDITIONS IN LOW CLOUDS AT LEAST TOWARD KINT AND KGSO
LATE SATURDAY NIGHT INTO SUNDAY MORNING...WITH SOME CHANCE OF THOSE
CLOUDS EXTENDING ACROSS THE REST OF CENTRAL NORTH CAROLINA. PERIODS
OF MVFR AND IFR CONDITIONS IN LOW CLOUDS...OR SHOWERS OR
THUNDERSTORMS...CONTINUE INTO EARLY NEXT WEEK...WITH THE BEST
POTENTIAL FOR SUSTAINED VFR CONDITIONS TUESDAY AFTERNOON INTO THE
OVERNIGHT HOURS OF TUESDAY...AND AGAIN AFTER MIXING DURING THE DAY
WEDNESDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DJF
NEAR TERM...DJF
SHORT TERM...DJF
LONG TERM...KMC
AVIATION...DJF
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
123 PM EDT FRI MAY 17 2013
.SYNOPSIS...
WARM TEMPERATURES WILL CONTINUE INTO EARLY NEXT WEEK AS BERMUDA
HIGH PRESSURE REMAINS ANCHORED OFFSHORE. A MID LEVEL DISTURBANCE
WILL BRING INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS OVER
THE WEEKEND INTO EARLY NEXT WEEK. DRIER WEATHER IS EXPECTED
THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1:30 PM FRIDAY...CONVECTIVE DEVELOPMENT HAS BEEN MEASURED AS EXPECTED
THIS AFTERNOON AS CUMULUS CLOUDS ARE JUST NOW BEGINNING TO
DEVELOP. THE LATEST GUIDANCE INCLUDING THE HIGH RESOLUTION RAP AND
GLOBAL GFS SHOW SOME ACTIVITY TO THE NORTH LATER THIS AFTERNOON. I
HAVE TWEAKED THE POPS TO REPRESENT THIS TREND OF WHICH THE FORCING
INCLUDES THE SEA BREEZE FRONT...POSSIBLY A RESIDUAL OUTFLOW FROM
ACTIVITY YESTERDAY AND A BACKDOOR FRONT. FOR THE OVERNIGHT
HOURS...I HAVE REMOVED POPS AFTER 0300 UTC. ENOUGH DEBRIS
CLOUDINESS SHOULD REMAIN TO PREVENT ANY SIGNIFICANT FOG
DEVELOPMENT. FOR THE OVERNIGHT LOWS...NUMERICAL GUIDANCE IS IN
EXCELLENT AGREEMENT WITH MIDDLE 60S ACROSS THE BOARD.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...WEAK PATTERN ALOFT COUPLED WITH BERMUDA HIGH AND
PIEDMONT TROUGH WILL RESULT IN AFTERNOON SHOWERS AND THUNDERSTORMS
SAT AND SUN. FOR SAT FLOW ALOFT REMAINS ZONAL AND FORECAST SOUNDINGS
SHOW SOME DRY AIR THROUGH THE COLUMN. STILL ANTICIPATE SOME STORM
DEVELOPMENT ALONG PIEDMONT TROUGH AND SEABREEZE BUT COVERAGE AND
STRENGTH WILL BE LIMITED.
COVERAGE SHOULD INCREASE SUN AS DEEPER MOISTURE ARRIVES AND WEAK 5H
SHORTWAVE TROUGH SLOWLY MOVES INTO BUILDING MID LEVEL RIDGE. MID
LEVEL LAPSE RATES REMAIN WEAK BUT FORECAST SOUNDINGS SHOW A
SIGNIFICANT INCREASE IN MOISTURE WITH PRECIPITABLE WATER VALUES
AROUND 1.9 INCH BY AFTERNOON. STEEP LOW LEVEL LAPSE RATES AND
PRESENCE OF PIEDMONT TROUGH AND SEABREEZE HELP GENERATE CONVECTION.
DEEPER MOISTURE AND ENHANCEMENT ALOFT WILL HELP SUSTAIN DEEPER
CONVECTION RESULTING IN WIDESPREAD AFTERNOON SHOWERS AND
THUNDERSTORMS. WEAK MID LEVEL LAPSE RATES...LIMITED DRY LOW LEVEL
AIR AND LACK OF STRONG JETTING SUGGEST STORMS WILL NOT BECOME SEVERE.
HIGHS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO WITH WARM ADVECTION BEING
OFFSET SOMEWHAT BY CLOUD COVER...ESPECIALLY ON SUN. LOWS WILL REMAIN
SEVERAL DEGREES ABOVE CLIMO EACH NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...DEEP MOISTURE AND WEAKNESS IN BUILDING MID LEVEL
RIDGE LINGERS OVER THE ARE MON...ONCE AGAIN CREATING AN ENVIRONMENT
SUPPORTIVE OF WIDESPREAD SHOWERS AND THUNDERSTORMS. AS IS THE CASE
ON SUN SEVERE PARAMETERS ARE LACKING SO STORMS ARE EXPECTED TO
REMAIN SUB-SEVERE.
PRECIP CHANCES START TO DECREASE TUE AS 5H RIDGE CONTINUES TO BUILD
IN FROM THE EAST AND THE WEAKNESS IN THE RIDGE FILLS IN. REMAINDER
OF THE PERIOD WILL BE DOMINATED BY THE 5H RIDGE AND THE BERMUDA
HIGH. FORECAST SOUNDINGS SHOW DRY AIR BELOW 12FT TUE EXPANDING
THROUGH THU AS SUBSIDENCE INVERSION STRENGTHENS. ABUNDANT MOISTURE
ABOVE 15K FT MAY KEEP CIRRUS AROUND THROUGH THE PERIOD BUT PRECIP
CHANCES WILL BE DIMINISHED. LATE IN THE PERIOD A COLD FRONT
APPROACHES FROM THE NORTHWEST BUT ITS ARRIVAL WILL BE WELL BEYOND
THE END OF THE PERIOD SO IT IS NOT A FACTOR AT THIS POINT.
HIGHS WILL BE WITHIN A FEW DEGREES OF CLIMO MON AND TUE BUT CLIMB
WELL ABOVE CLIMO BY THE END OF THE PERIOD. LOWS WILL REMAIN WELL
ABOVE CLIMO THROUGH THE PERIOD.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 18Z...EXPECT VFR THROUGH THE VALID PERIOD...WITH THE EXCEPTION
OF POSSIBLE AREAS OF FOG SATURDAY MORNING.
FOR THE REST OF THE DAY EXPECT SCT/BKN MID TO HIGH LEVEL CLOUDS WITH
SOUTHWEST WINDS AOB 10 KTS...BECOMING MORE SOUTH ALONG THE COAST
WITH THE AFTERNOON SEABREEZE. WOULD NOT COMPLETELY RULE OUT AN
ISOLATED SHOWER THIS AFTERNOON...BUT CONFIDENCE IS LOW. INTO THE
OVERNIGHT HOURS...CLOUD COVERAGE WILL CONTINUE...AND LIKELY
INCREASE...WITH WINDS BECOMING LIGHT. TOWARDS THE EARLY MORNING
HOURS ON SATURDAY...CANNOT RULE OUT PATCHY FOG...ESPECIALLY INLAND.
TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS SUGGEST POSSIBILITY OF
FEW/SCT LOW CLOUDS IN THE MORNING AS WELL. AFTER DAYBREAK...CLOUDS
WILL GRADUALLY BEGIN TO SCATTER OUT WITH SOUTHWEST WINDS AOB 8 KTS.
EXTENDED OUTLOOK...CHANCE OF AFTN SHOWERS/TSTMS SATURDAY THROUGH
MONDAY...OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1:30 PM FRIDAY...PERSISTENCE WILL BE THE THEME FOR THE COASTAL
WATERS THROUGH TONIGHT AS A SOUTHWEST FLOW OF 10-15 KNOTS PREVAILS.
WAVEWATCH SEAS WILL CONTINUE IN A 2-4 FOOT RANGE. THE BACKDOOR FRONT
SHOULD STAY WELL TO THE NORTH PRECLUDING ANY WIND SHIFT.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...SOUTHWEST FLOW WILL CONTINUE THROUGH THE PERIOD
AS BERMUDA HIGH REMAINS IN CONTROL. GRADIENT WILL PRODUCE SPEEDS IN
THE 10 TO 15 KT RANGE WITH SPEEDS EACH AFTERNOON ON THE HIGHER END
OF THE RANGE. SEAS WILL RUN 2 TO 4 FT WITH SOUTHEAST SWELL BECOMING
A LITTLE MORE APPARENT.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...SUMMER PATTERN CONTINUES WITH BERMUDA HIGH
KEEPING SOUTH TO SOUTHWEST FLOW BETWEEN 10 AND 15 KT. HIGHEST SPEEDS
WILL OCCUR IN THE AFTERNOON. SEAS 2 TO 4 FT THROUGH THE PERIOD WILL
BE A MIX OF WIND WAVE AND SOUTHEAST SWELL.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...SHK
SHORT TERM...III
LONG TERM...III
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1036 AM EDT FRI MAY 17 2013
.SYNOPSIS...
WARM TEMPERATURES WILL CONTINUE INTO EARLY NEXT WEEK AS BERMUDA
HIGH PRESSURE REMAINS ANCHORED OFFSHORE. A MID LEVEL DISTURBANCE
WILL BRING INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS OVER
THE WEEKEND INTO EARLY NEXT WEEK. DRIER WEATHER IS EXPECTED
THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10:30 AM FRIDAY...ONLY FORECAST CHALLENGE IS POPS FOR THE LATE
AFTERNOON/EVENING HOURS. 0600 GFS STILL SHOWS SOME LIMITED/SHALLOW
ACTIVITY ACROSS THE PIEDMONT WHICH IS SEA BREEZE DRIVEN. FURTHER
NORTH ACTIVITY APPEARS TO BE A LITTLE MORE ORGANIZED BUT FOR THE
MOST PART IS NORTH OF OUR AREA. 0900 RAP GUIDANCE ONLY SHOWS THE
ACTIVITY TO THE NORTH. OVERALL THERE IS NO REASON TO REMOVE SLIGHT
CHANCE POPS BUT WITH THE 1200 UTC MHX SOUNDING SHOWING A CONVECTIVE
TEMPERATURE OF 90 DEGREES F...IT WILL BE LATE. NO CHANGES TO
TEMPERATURE FORECAST.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...WEAK PATTERN ALOFT COUPLED WITH BERMUDA HIGH AND
PIEDMONT TROUGH WILL RESULT IN AFTERNOON SHOWERS AND THUNDERSTORMS
SAT AND SUN. FOR SAT FLOW ALOFT REMAINS ZONAL AND FORECAST SOUNDINGS
SHOW SOME DRY AIR THROUGH THE COLUMN. STILL ANTICIPATE SOME STORM
DEVELOPMENT ALONG PIEDMONT TROUGH AND SEABREEZE BUT COVERAGE AND
STRENGTH WILL BE LIMITED.
COVERAGE SHOULD INCREASE SUN AS DEEPER MOISTURE ARRIVES AND WEAK 5H
SHORTWAVE TROUGH SLOWLY MOVES INTO BUILDING MID LEVEL RIDGE. MID
LEVEL LAPSE RATES REMAIN WEAK BUT FORECAST SOUNDINGS SHOW A
SIGNIFICANT INCREASE IN MOISTURE WITH PRECIPITABLE WATER VALUES
AROUND 1.9 INCH BY AFTERNOON. STEEP LOW LEVEL LAPSE RATES AND
PRESENCE OF PIEDMONT TROUGH AND SEABREEZE HELP GENERATE CONVECTION.
DEEPER MOISTURE AND ENHANCEMENT ALOFT WILL HELP SUSTAIN DEEPER
CONVECTION RESULTING IN WIDESPREAD AFTERNOON SHOWERS AND
THUNDERSTORMS. WEAK MID LEVEL LAPSE RATES...LIMITED DRY LOW LEVEL
AIR AND LACK OF STRONG JETTING SUGGEST STORMS WILL NOT BECOME SEVERE.
HIGHS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO WITH WARM ADVECTION BEING
OFFSET SOMEWHAT BY CLOUD COVER...ESPECIALLY ON SUN. LOWS WILL REMAIN
SEVERAL DEGREES ABOVE CLIMO EACH NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...DEEP MOISTURE AND WEAKNESS IN BUILDING MID LEVEL
RIDGE LINGERS OVER THE ARE MON...ONCE AGAIN CREATING AN ENVIRONMENT
SUPPORTIVE OF WIDESPREAD SHOWERS AND THUNDERSTORMS. AS IS THE CASE
ON SUN SEVERE PARAMETERS ARE LACKING SO STORMS ARE EXPECTED TO
REMAIN SUB-SEVERE.
PRECIP CHANCES START TO DECREASE TUE AS 5H RIDGE CONTINUES TO BUILD
IN FROM THE EAST AND THE WEAKNESS IN THE RIDGE FILLS IN. REMAINDER
OF THE PERIOD WILL BE DOMINATED BY THE 5H RIDGE AND THE BERMUDA
HIGH. FORECAST SOUNDINGS SHOW DRY AIR BELOW 12FT TUE EXPANDING
THROUGH THU AS SUBSIDENCE INVERSION STRENGTHENS. ABUNDANT MOISTURE
ABOVE 15K FT MAY KEEP CIRRUS AROUND THROUGH THE PERIOD BUT PRECIP
CHANCES WILL BE DIMINISHED. LATE IN THE PERIOD A COLD FRONT
APPROACHES FROM THE NORTHWEST BUT ITS ARRIVAL WILL BE WELL BEYOND
THE END OF THE PERIOD SO IT IS NOT A FACTOR AT THIS POINT.
HIGHS WILL BE WITHIN A FEW DEGREES OF CLIMO MON AND TUE BUT CLIMB
WELL ABOVE CLIMO BY THE END OF THE PERIOD. LOWS WILL REMAIN WELL
ABOVE CLIMO THROUGH THE PERIOD.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...ANOTHER HOUR OR TWO OF PATCHY FOG THIS MORNING
INLAND...WITH THE POTENTIAL FOR FOG AGAIN SATURDAY MORNING.
OTHERWISE EXPECT VFR.
MID TO HIGH CLOUDS LINGERING ACROSS THE AREA THIS MORNING...WITH
TEETERING MVFR/IFR FOG AT KLBT. EXPECT FOG TO DISSIPATE WITHIN THE
NEXT HOUR OR TWO...GIVING WAY TO VFR AREA-WIDE FOR THE REST OF THE
DAY WITH SCT/BKN MID TO HIGH LEVEL CLOUDS. SOUTHWEST WINDS AOB 10
KTS EXPECTED TODAY...BECOMING SOUTH ALONG THE COAST WITH THE
AFTERNOON SEABREEZE. WOULD NOT COMPLETELY RULE OUT AN ISOLATED
SHOWER OR THUNDERSTORM THIS AFTERNOON...BUT CONFIDENCE IS LOW.
INTO THE OVERNIGHT HOURS...CLOUD COVERAGE WILL CONTINUE...AND
LIKELY INCREASE...WITH WINDS BECOMING LIGHT. TOWARDS THE EARLY
MORNING HOURS ON SATURDAY...CANNOT RULE OUT PATCHY
FOG...ESPECIALLY INLAND.
EXTENDED OUTLOOK...CHANCE OF AFTN SHOWERS/TSTMS SATURDAY THROUGH
MONDAY...OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10:30 AM FRIDAY...LATEST BUOY OBSERVATIONS SHOW FORECAST IS ON
TRACK. NO CHANGES WARRANTED. SUMMERTIME PATTERN REMAINS IN FULL
FORCE WITH A SOUTHWEST FLOW OF 10-15 KNOTS AND SEAS OF 2-4 FEET.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...SOUTHWEST FLOW WILL CONTINUE THROUGH THE PERIOD
AS BERMUDA HIGH REMAINS IN CONTROL. GRADIENT WILL PRODUCE SPEEDS IN
THE 10 TO 15 KT RANGE WITH SPEEDS EACH AFTERNOON ON THE HIGHER END
OF THE RANGE. SEAS WILL RUN 2 TO 4 FT WITH SOUTHEAST SWELL BECOMING
A LITTLE MORE APPARENT.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...SUMMER PATTERN CONTINUES WITH BERMUDA HIGH
KEEPING SOUTH TO SOUTHWEST FLOW BETWEEN 10 AND 15 KT. HIGHEST SPEEDS
WILL OCCUR IN THE AFTERNOON. SEAS 2 TO 4 FT THROUGH THE PERIOD WILL
BE A MIX OF WIND WAVE AND SOUTHEAST SWELL.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...SHK
SHORT TERM...III
LONG TERM...III
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1006 AM EDT FRI MAY 17 2013
.SYNOPSIS...
A COLD FRONT OVER THE OHIO VALLEY AND MID ATLANTIC WILL GRADUALLY
MOVE SOUTH INTO OUR REGION WHILE AN UPPER LEVEL LOW PRESSURE SYSTEM
MOVES IN FROM THE WEST. BOTH THE FRONT AND THE UPPER LEVEL LOW WILL
LINGER AROUND OUR AREA THROUGH THE WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 1005 AM FRIDAY...
REST OF TODAY:
THE LATEST SURFACE ANALYSIS SHOWED A NEARLY STATIONARY FRONT OVER
THE OHIO VALLEY INTO THE MID ATLANTIC...WITH THE EASTERN PART OF THE
FRONT OFFSHORE SAGGING SOUTH EAST OF NORFOLK BENEATH HIGH PRESSURE.
A SURFACE TROUGH WAS LOCATED OVER THE FOOTHILLS AND WESTERN
PIEDMONT...WHILE A WEAKENING OUTFLOW BOUNDARY WHICH TURNED MANY
WINDS TO THE NORTH AND NORTHEAST NORTH OF ABOUT U.S. 64 WAS PRETTY
DIFFUSE. SKIES HAD CLEARED ACROSS MUCH OF CENTRAL NORTH CAROLINA
BEHIND A MID-LEVEL SHORTWAVE MOVING THROUGH THE AREA...WITH THE
SHORT-TERM GUIDANCE CONTINUING TO FORECASDT MID-LEVEL RIDGING IN
PLACE COINCIDENT WITH THE 12Z UPPER-AIR ANALYSIS.
FOR THE AFTERNOON...IT WILL BE INTERESTING TO SEE HOW SURFACE DEW
POINTS REACT TO MIXING...AS THE RAP IS VERY AGGRESSIVE DRYING
SURFACE DEW POINTS OVER THE WESTERN PIEDMONT ALMOST INTO THE 40S...
WHILE THE NAM AND GFS MAINTAIN MUCH HIGHER DEW POINTS...AT LEAST
WELL INTO THE 50S. A COUPLE OF THINGS ARE IN FAVOR OF THE RAP...
WITH A RELATIVE MINIMUM OF DEW POINTS ALREADY OVER THE FOOTHILLS AND
WESTERN PIEDMONT...AND THE RECENT TRACK RECORD OF GUIDANCE OVER THE
LAST 24 HOURS BEING MUCH TOO AGGRESSIVE WITH THE MOISTURE INCREASE
IN THE AIR MASS OVER CENTRAL NORTH CAROLINA. IN FACT...PRECIPITABLE
WATER VALUES WERE ONLY AROUND AN INCH AT BOTH KGSO AND KRNK...
COMPARED TO THE NEARLY 1.5 INCHES FORECAST BY THIS TIME BY THE
GUIDANCE DURING THE DAY THURSDAY. EVEN ON THE MORE MOIST BUFR
SOUNDINGS OF THE NAM AND GFS...MODEST CAPPING EXISTS AROUND 750MB...
PARTICULARLY ON THE GFS. WITH LIMITED FORCING ALOFT...THINK ANY DEEP
CONVECTION WILL NEED TO GENERATE OUTSIDE OF CENTRAL NORTH CAROLINA
AND MOVE IN...DELAYING CHANCES AND PUSHING THEM A LITTLE FARTHER
NORTH. THE LATEST HRRR WRF SHOWS ONLY SPOTTY PRECIPITATION NORTH OF
ABOUT U.S. 64 AFTER 20Z...AND THE LOCAL WRF IS VERY SIMILAR. RAISED
MAXES ABOUT A DEGREE IN MOST LOCATIONS GIVEN MORE SUN...TWO TO THREE
DEGREES OVER THE SOUTHWEST PIEDMONT IN EXPECTED DRIER CONDITIONS AND
MORE SUN. -DJF
TONIGHT:
WITH WEAK S/W RIDGING HOLDING ON ACROSS THE AREA TONIGHT... EXPECT
ANY AFTERNOON AND EVENING SHOWERS/STORMS SHOULD DWINDLE WITH
NOCTURNAL COOLING AND RESULTANT STABILIZATION OF THE BOUNDARY LAYER.
THUS... WILL TREND POPS TO A SLIGHT CHANCE AFTER MIDNIGHT. CANNOT
RULE OUT ANY LOCALIZED AREA OF FOG AND LOW CLOUDS DEPENDING ON IF
AND WHERE ANY LOCALIZED HEAVY PRECIP FALLS TODAY. EXPECT LOW TEMPS
TONIGHT WILL AGAIN BE ABOVE NORMAL IN THE MID TO UPPER 60S.
SATURDAY:
THE WEAK MID LEVEL LOW OVER THE OZARKS THIS MORNING WILL CONTINUE
SLOWLY SHIFT EASTWARD ON SATURDAY WHILE OPENING UP AND WEAKENING...
WHILE MOVING INTO THE CENTRAL AND SOUTHERN APPALACHIANS. BOTH THE
GFS AND ECMWF DEPICT THIS DISTURBANCE SHOULD BE CLOSE ENOUGH TO THE
AREA TO SUPPORT HIGHER POPS ON SATURDAY (WITH THE NAM TRYING TO HOLD
IT OFF MORE). THUS... WILL CONTINUE TO GO WITH A WETTER SOLUTION.
MLCAPE VALUES ARE EXPECTED TO TOP OUT IN THE 1500 TO 2000 J/KG RANGE
ACROSS THE PIEDMONT. STILL DEEP LAYER SHEAR WILL REMAIN WEAK (LESS
THAN 20 KTS AGAIN)... RESULTING IN A LOW SEVERE POTENTIAL AGAIN.
HOWEVER... WE MAY HAVE A LOCALIZED FLOODING THREAT WITH THE EXPECTED
SLOW MOTION OF THE SHOWERS/STORMS AND EXPECTED GREATER COVERAGE.
THUS... WILL HIGHLIGHT THIS THREAT FOR LOCALIZED FLOODING/EXCESSIVE
RAINFALL IN THE HWO. HIGHS SATURDAY WILL BE LOWER WITH THE FRONT TO
THE NORTH TRYING TO OOZE DOWN INTO NORTHERN PORTIONS OF OUR AREA AND
GREATER COVERAGE OF SHOWERS AND STORMS. THUS WILL GO WITH UPPER 70S
NORTH TO MID 80S SOUTH. EXPECT THE BEST COVERAGE OF SHOWERS AND
STORMS WILL AGAIN BE ACROSS THE NORTHERN HALF OF THE AREA... CLOSER
TO THE BEST SURFACE CONVERGENCE. THUS.. WILL GO WITH LIKELY POPS
NORTH TO CHANCE SOUTH. -BSD
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 301 AM FRIDAY...
WET AND UNSETTLED PERIOD SETTING UP FOR CENTRAL NC WITH A
POSSIBILITY OF LOCALLY EXCESSIVE RAINFALL.
SATURDAY NIGHT INTO SUNDAY...MODELS IN GOOD CONSENSUS WITH AN UPPER
LEVEL LOW OVER THE LOWER OH VALLEY SATURDAY EVENING DRIFTING SLOWLY
SEWD INTO EASTERN KY BY SUNDAY AFTERNOON. MEANWHILE A STALLED SFC
BOUNDARY WILL STRETCH WEST-TO-EAST IN VICINITY OF THE NC/VA BORDER.
THE APPROACH OF THE UPPER LEVEL LOW WILL INCREASE LOW LEVEL SLY
FLOW...MADE EVIDENT BY 850MB FLOW INCREASING FROM 15 KTS SATURDAY
EVENING TO 25-30KTS BY SUNDAY EVENING. THIS FLOW WILL PUMP MOISTURE
OFF THE ATLANTIC AND EASTERN GULF INTO THE CAROLINAS...INCREASING
PRECIPITABLE WATER VALUES TO AS HIGH AS 1.75 INCHES BY SUNDAY
EVENING. THE UPPER LEVEL LOW WILL ALSO INCREASE MID-UPPER DIVERGENCE
OVER THE REGION. THUS THE COMBINATION OF INCREASING LOW LEVEL
CONVERGENCE...INCREASING DIVERGENCE ALOFT...AND A VERY MOIST AIR
MASS WILL SUSTAIN SCATTERED SHOWERS ACROSS THE REGION SATURDAY
NIGHT...MAINLY NORTH AND WEST...AND LEAD TO THE DEVELOPMENT OF
NUMEROUS SHOWERS AND A FEW T-STORMS SUNDAY AFTERNOON-SUNDAY NIGHT.
WILL MAINTAIN LIKELY POPS ACROSS THE NORTH HALF FOR NORTH WITH SOLID
CHANCE POPS SOUTH-SOUTHEAST. MAX TEMPS SUNDAY WILL BE AFFECTED BY
OVERCAST SKIES AND NUMEROUS SHOWERS. MAX TEMPS LOWER 80S
SOUTH-SOUTHEAST TO THE UPPER 70S NORTH.
SUNDAY NIGHT THROUGH MONDAY NIGHT...UPPER LEVEL LOW SLOWLY OPENS UP
AND DRIFTS EAST ACROSS THE FORECAST AREA DURING THIS TIME.
ASSOCIATED MID LEVEL TROUGH WILL ALSO DRIFT EAST WITH TIME BUT HELP
TO FOCUS MOST OF THE SHOWERS AND SCATTERED T-STORMS ALONG AND EAST
OF HIGHWAY 1 BY MONDAY AFTERNOON. STALLED SFC BOUNDARY IN VICINITY
OF THE VA BORDER WILL CONTINUE TO SERVE AS A FOCUS FOR LOW LEVEL
CONVERGENCE AND MOISTURE POOLING. THUS STILL FAVOR HIGHER POPS
(LIKELY) ACROSS THE NORTH-NORTHEAST THIS PERIOD...TRENDING TO HIGH
CHANCE OR LOW END LIKELY SOUTH. MONDAY MAX TEMPS AGAIN HAMPERED BY
EXTENSIVE CLOUDINESS AND SCATTERED-NUMEROUS SHOWERS. MAX TEMPS UPPER
70S/NEAR 80 NORTH TO LOWER 80S SOUTH. MIN TEMPS MID 60S.
PRESENCE OF THE STALLED SFC BOUNDARY ACROSS THE NORTH WILL AID TO
FOCUS MOST OF THE SHOWER DEVELOPMENT. WITH PRECIP WATER VALUES
AROUND 1.6-1.75 INCHES LATE SATURDAY THROUGH MONDAY NIGHT...SHOWERS
AND STORMS WILL BE EFFICIENT RAIN PRODUCERS. HPC HAS AN AREA OF THE
NC PIEDMONT AND SOUTHERN VA OUTLINED FOR THE POSSIBILITY OF
EXCESSIVE RAINFALL WITH AMOUNTS IN EXCESS OF 3 INCHES (EQUIVALENT TO
A MONTHS WORTH OF RAIN) POSSIBLE NEAR THE VIRGINIA BORDER LATE
SATURDAY THROUGH MONDAY EVENING. CURRENTLY...WENT A BIT MORE
CONSERVATIVE AND HAVE STORM TOTAL PRECIP AMOUNTS 2-2.5 INCHES IN
THIS REGION. HOWEVER THIS SET-UP USUALLY LEAD TO LOCALLY EXCESSIVE
RAINFALL SO COULD SEE HIGHER AMOUNTS IN THIS REGION. PLAN TO MENTION
THREAT FOR LOCALLY EXCESSIVE RAINFALL IN THE HAZARDOUS WEATHER
OUTLOOK.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 301 AM FRIDAY...
TUESDAY THROUGH WEDNESDAY...WEAK SUBSIDENCE BEHIND THE EXITING
MID/UPPER LEVEL TROUGH WILL AID TO DRY OUT THE AIR MASS. A SLIGHTLY
MORE STABLE AND DRIER AIR MASS WILL LEAD TO FEWER SHOWERS AND STORMS
IN THE AFTERNOON. IN ADDITION...THIS WILL LEAD TO WARMER AFTERNOON
TEMPS. WILL MAINTAIN A SLIGHT CHANCE POP EVERYWHERE TO COVER THREAT
OF AFTERNOON CONVECTION WHILE MAX TEMPS WILL BE REFLECTIVE OF THE
EARLY SUMMER PATTERN IN THE LOW-MID 80S.
BY THURSDAY...GFS MUCH MORE AGGRESSIVE WITH ITS EWD MOVEMENT OF A
S/W TROUGH AND ASSOCIATED SFC FRONT INTO THE MID ATLANTIC AND
CAROLINAS. ECMWF MUCH SLOWER WITH BEST UPPER SUPPORT OVER THE GREAT
LAKES AND LOWER OH VALLEY. FAVOR THE SLOWER ECMWF AT THIS TIME.
THUS...WILL LOWER POPS THURSDAY FROM PREVIOUS FORECAST WITH SLIGHT
CHANCE OF AFTERNOON CONVECTION AND HIGHS TEMPS SOLIDLY IN THE MID
80S. MIN TEMPS THROUGH THE PERIOD MAINLY IN THE MID 60S.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AS OF 1005 AM FRIDAY...
MAINLY VFR CONDITIONS WILL PREVAIL THROUGH THE 12Z TAF PERIOD. THE
POSSIBLE EXCEPTION WILL RESULT FROM ISOLATED-TO-SCATTERED SHOWERS
AND STORMS MAINLY FOCUSED LATE THIS AFTERNOON FROM TRIAD TERMINALS
TO KRDU AND KRWI AND POSSIBLY SOME LOW STRATUS AND/OR FOG IN THE
PRE-DAWN HOURS OF SATURDAY. WILL KEEP ONLY VICINITY SHOWERS
MENTIONED IN THE TAFS FROM THIS AFTERNOON INTO THE EVENING...GIVEN
BOTH THE TIMING AND COVERAGE UNCERTAINTY WITH ANY SHOWERS AND
STORMS. WILL GO WITH A LIGHT AND VARIABLE WIND ACROSS THE THE
NORTHERN TAF SITES... WITH MORE OF A SOUTHWESTERLY WIND AT KFAY
THROUGH EARLY AFTERNOON... BEFORE OUTFLOW FROM ANY SHOWERS AND
STORMS TO THE NORTH MAY RESULT IN VARIABLE WINDS FOR KFAY AS WELL.
EXPECT THE BULK OF THE PRECIP TO DISSIPATE AND DWINDLE IN COVERAGE
LATE THIS EVENING WITH THE LOSS OF DAYTIME HEATING. WE MAY SEE SOME
PATCHY FOG AND/OR LOW STRATUS DEVELOP TONIGHT ACROSS THE AREA.
HOWEVER...WILL NOT MENTION ANY RESTRICTIONS IN THE TAFS AT THIS TIME
GIVEN THE SUB-VFR CONDITIONS WILL BE DRIVEN BY WHERE THE RAIN FALLS
AND THE AMOUNT OF MID AND HIGH LEVEL CLOUD COVER STREAMING INTO THE
AREA FROM THE WEST.
LOOKING AHEAD: AS A COLD FRONT APPROACHES FROM THE NORTH...AND AN
UPPER-LEVEL LOW APPROACHES FROM THE WEST...THE CHANCES FOR UNSETTLED
WEATHER INCREASE. SCATTERED-TO-NUMEROUS SHOWERS AND THUNDERSTORMS
ARE EXPECTED OVER THE WEEKEND. SCATTERED SHOWERS AND THUNDERSTORMS
SHOULD CONTINUE EARLY NEXT WEEK AS WELL. THE CHANCE FOR LATE NIGHT
AND EARLY MORNING LOW CLOUDS AND FOG WILL INCREASE INTO THE WEEKEND
AND EARLY NEXT WEEK IN A MOIST AIR MASS AS WELL.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS/DJF
NEAR TERM...DJF/BSD
SHORT TERM...WSS
LONG TERM...WSS
AVIATION...BSD/MWS/DJF
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1006 PM CDT SAT MAY 18 2013
.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 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 716 PM CDT SAT MAY 18 2013
IFR/LIFR CIGS AFFECTING KBJI AND KDVL...WITH MVFR CIGS AFFECTING
KTVF AND KGFK...AS THESE SITE ARE WITHIN LOW LEVEL NORTHERLY FLOW.
NOT IF THESE CONDITIONS WILL CONTINUE THROUGH THE NIGHT. MOST
GUIDANCE SUGGESTS THAT AN AREA OF THUNDERSTORMS AND/OR SHOWERS
WILL MOVE THROUGH THESE SITES...WHICH SHOULD BRIEFLY RAISE CIGS.
UNTIL THEN...EXPECT THE LOWER CIGS TO CONTINUE. CIGS SHOULD LOWER
THROUGH THE DAY ON SUNDAY WITH SHOWER CHANCES INCREASING. FOR
KFAR...EXPECT THUNDER CHANCES TO INCRASE BY MIDNIGHT...ALONG WITH
LOWERING CIGS.
&&
.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 GRAND FORKS ND
716 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 716 PM CDT SAT MAY 18 2013
THE SITUATION FOR TONIGHT IS BECOMING A LITTLE MORE CLEAR. THERE
IS SUBTLE SHORTWAVE ACROSS THE WESTERN DAKOTAS WHICH HAS INITIATED
A THUNDERSTORM COMPLEX THAT IS HEADING TO THE EAST. THERE IS ALSO
AN ISOLATED SEVERE STORM WITHIN BECKER COUNTY ALONG A WEAK
SURFACE BOUNDARY...AND ANOTHER AREA OF STORMS JUST SOUTH OF THE FA
ALONG ANOTHER WEAK BOUNDARY. THE GENERAL IDEA IS THAT THE COMPLEX
TO THE WEST WILL MOVE THROUGH THE REGION LATER THIS EVENING AND
OVERNIGHT. MEANWHILE...ACTIVITY FROM THE SOUTH WILL GROW IN
COVERAGE AND MOVE INTO THE SOUTHERN FA (GRADUALLY MOVING NORTH
THROUGH THE REGION ON SUNDAY). UPDATED POP GRIDS TO REFLECT THIS
THINKING (ISOLATED THIS EVENING WITH POPS INCREASING).
OVERALL THE SEVERE THREAT APPEARS LIMITED...WITH THE BEST THREAT
ACROSS THE SOUTHERN FA WHERE MLCAPE IS CURRENTLY AROUND 1000 J/KG.
THE ISOLATED ACTIVITY AHEAD OF THE WESTERN COMPLEX HAS THE
POTENTIAL TO PRODUCE LARGE HAIL AND STRONG WIND GUSTS...BUT
COVERAGE WILL BE LIMITED. THE MAIN CONCERN WILL BE THE COMPLEX
APPROACHING FROM THE WEST. LATEST HRRR INDICATES THE POTENTIAL FOR
BOWING AND STRONG WINDS ACROSS SOUTHERN NORTH DAKOTA. NOT SURE IF
THIS WILL HOLD TOGETHER BY THE TIME IT ENTERS SE ND...BUT WILL
MONITOR.
ALSO STILL NOT SURE ABOUT A FLASH FLOOD THREAT. WILL MONITOR
TRENDS AND THE SPEED OF THESE STORM OVER THE NEXT FEW HOURS AND
ATTEMPT TO DETERMINE IF HEAVY RAIN IN A SHORT DURATION IS POSSIBLE
TONIGHT. HEAVY RAIN WILL OCCUR...JUST NOT SURE IF THE STORMS WILL
BE MOVING SLOW ENOUGH TO PRODUCE FLASH FLOODING.
&&
.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 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 716 PM CDT SAT MAY 18 2013
IFR/LIFR CIGS AFFECTING KBJI AND KDVL...WITH MVFR CIGS AFFECTING
KTVF AND KGFK...AS THESE SITE ARE WITHIN LOW LEVEL NORTHERLY FLOW.
NOT IF THESE CONDITIONS WILL CONTINUE THROUGH THE NIGHT. MOST
GUIDANCE SUGGESTS THAT AN AREA OF THUNDERSTORMS AND/OR SHOWERS
WILL MOVE THROUGH THESE SITES...WHICH SHOULD BRIEFLY RAISE CIGS.
UNTIL THEN...EXPECT THE LOWER CIGS TO CONTINUE. CIGS SHOULD LOWER
THROUGH THE DAY ON SUNDAY WITH SHOWER CHANCES INCREASING. FOR
KFAR...EXPECT THUNDER CHANCES TO INCRASE BY MIDNIGHT...ALONG WITH
LOWERING CIGS.
&&
.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 GRAND FORKS ND
345 PM CDT FRI MAY 17 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM CDT FRI MAY 17 2013
THE MAIN CONCERNS WILL BE HEAVY RAIN AND SEVERE POTENTIAL. 12Z
MODELS IN DECENT AGREEMENT WITH SYNOPTIC FEATURES...BUT STILL
ENOUGH DIFFERENCES THAT CONFIDENCE IS LOW WITH DETAILS.
WEST COAST TROUGH WILL GRADUALLY PROPAGATE EAST WITH MULTIPLE
SHORTWAVES EJECTING INTO THE REGION. HARD TO PINPOINT EXACTLY WHEN
AND WHERE THE BEST THUNDER CHANCES WILL BE...BUT THE MODELS DO
OFFER A COUPLE STRONGER SIGNALS. THE FIRST BEST CHANCE IS TONIGHT
INTO SATURDAY MORNING AS MENTIONED IN THE PREVIOUS AFD (1243PM).
18Z HRRR DOES INDICATE A THUNDERSTORM COMPLEX MOVING INTO THE
SOUTHERN FA AFTER 06Z...ALONG WITH WITH ISOLATED STRONGER STORMS.
THIS COMPLEX SHOULD MOVE THROUGH FAIRLY QUICKLY...WITH UP TO 0.5
INCH AREAL QPF POSSIBLE.
THINKING THERE WILL BE A BRIEF BREAK IN ACTIVITY ON SATURDAY.
SEVERE POTENTIAL WILL DEPEND ON HOW FAR NORTH THE SURFACE WARM
FRONT WILL MAKE IT BY SATURDAY AFTERNOON. THE GEM/GFS BRING THIS
FEATURE MUCH FURTHER NORTH THAN OTHER MODELS (LIKELY BECAUSE THEY
ARE STRONGER WITH A SHORTWAVE INTO SOUTHERN CANADA). AT ANY
RATE...GIVEN THIS TIME OF YEAR WITHOUT EVAPOTRANSPIRATION...THE
NAM SEEMS TO HAVE THE CORRECT IDEA INDICATING MLCAPE 1000-1500
J/KG WITHIN THE WARM SECTOR. THIS INSTABILITY ALONG WITH DEEP
LAYER SHEAR 30-35 KNOTS SHOULD BE ENOUGH FOR LIMITED SEVERE
POTENTIAL WITHIN THE WARM SECTOR AS THE COLD FRONT SLOWLY
PROPAGATES EAST INTO THE EVENING HOURS.
THE BEST CHANCE FOR FLASH FLOODING POTENTIAL WOULD BE SATURDAY
EVENING AND OVERNIGHT ALONG THE SLOW MOVING BOUNDARY. THE BIGGEST
QUESTIONS AT THIS POINT WILL BE THE EXACT LOCATION OF THIS
FEATURE...AND HOW QUICKLY IT WILL MOVE TO THE EAST. NOT ENOUGH
CONFIDENCE FOR A FLASH FLOOD WATCH AT THIS POINT...BUT THERE IS A
SLIGHT RISK FOR FLASH FLOODING ALONG AND EAST OF THE VALLEY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 PM CDT FRI MAY 17 2013
SUNDAY-MONDAY...UPPER LOW WILL CLOSE OFF JUST SOUTH OF THE FA AND
BRING PERIODIC SHOWERS AND THUNDERSTORMS TO THE REGION.
INSTABILITY IS MUCH WEAKER BY THIS TIME...BUT GIVEN HIGH PWATS AN
ADDITIONAL 1-2 INCHES OF RAINFALL IS POSSIBLE (ESPECIALLY THE
SOUTHERN HALF OF THE FA). THIS RAINFALL WOULD OVER A COUPLE DAYS
AND ANY FLOOD THREAT IS DEPENDENT ON WHAT OCCURS SATURDAY/SATURDAY
NIGHT.
MONDAY NIGHT-FRIDAY...12Z GFS/12Z ECMWF IN PRETTY GOOD AGREEMENT
IN SHOWING THE 500 MB LOW OVER EASTERN SD/MN REGION TUESDAY THEN
DRIFTING A BIT SOUTH AND EAST WEDNESDAY AND THEN EAST OF THE AREA
THURSDAY. LOOK FOR A CONTINUED HIGH THREAT FOR SHOWERS
TUESDAY...DIMINISHING ON WEDNESDAY. A 500 MB RIDGE WILL BUILD IN
BEHIND THE LOW FOR THE END OF THE WEEK WITH DRY WEATHER RETURNING.
LOOK FOR TEMPS TO BIT A BIT BELOW NORMAL WITH THE CLOUDS/RAIN TUE-
WED THEN RETURN TO CLOSE TO NORMAL LEVELS BY LATE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1243 PM CDT FRI MAY 17 2013
QUESTION FOR THIS PERIOD WILL BE HOW FAR NORTH THE MVFR CLOUDS
SPREAD DURING THE NIGHT INTO SATURDAY MORNING AND PRECIPITATION
(THUNDER) CHANCES. THRU 00Z FORSEE ALL SITES STAYING VFR..BUT
WATCHING AN AREA OF HIGHER DEW POINTS ALONG WITH 25-35K FT CLOUD
DECK MOVING SLOWLY NORTHWEST FROM WCNTRL MN AND ECNTRL SD. TIMING
OF THIS MOVEMENT NORTHWEST INTO FARGO AREA IS SUSPECT...BUT LATEST
RAP MODEL SUGGEST 03Z-06Z PERIOD. THESE CONDITIONS MAY REACH THE
OTHER TAF SITES TOWARD 12Z. PRECIP (THUNDER) CHANCES LATER TONIGHT
INTO SATURDAY MORNING AND WHEN/HOW IT AFFECTS ANY TAF SITE IS QUITE
DIFFICULT TO DETERMINE NOW. FOR NOW JUST INCLUDED A TEMPO GROUP FOR
FARGO AS BEST CHANCE APPEARS THERE OVERNIGHT. WINDS WILL REMAIN
SOUTHEAST MOSTLY 10 TO 20 KTS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
SHORT TERM...TG
LONG TERM...TG/RIDDLE
AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1243 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 1243 PM CDT FRI MAY 17 2013
SCATTERED SHOWERS ACROSS THE NW FA WILL EXIT BY LATER THIS
AFTERNOON AS ASSOCIATED UPPER WAVE PROPAGATES INTO CANADA.
CLEAR SKIES REMAIN ACROSS PORTIONS OF THE SOUTHERN FA...AND
TEMPERATURES WITHIN THIS AREA ARE NOW INTO THE 70S. THE TREND OF
BECOMING CLOUDY STILL LOOKS GOOD...BUT IT WILL TAKE SOME TIME.
INCREASED MAX TEMPS INTO THE MID-UPPER 70S WITHIN THE CLEAR
AREA...AND SLOWED DOWN THE PROGRESSION OF THIS AREA BECOMING
CLOUDY. THE OTHER ISSUE WILL BE THUNDER CHANCES TONIGHT. FOLLOWING
THE LATEST RAP/HRRR GUIDANCE AND 12Z NAM/GFS...THERE WILL BE A
SURGE OF INSTABILITY AS 850MB WINDS AND WARM AIR ADVECTION
INCREASE (ALONG ELEVATED WARM FRONT). THIS WILL HAPPEN CLOSER TO
03Z-06Z ACROSS THE SOUTHERN FA. THE RAP INDICATES 850MB CAPE ABOVE
1000 J/KG ALONG WITH AROUND 35 KNOTS OF DEEP LAYER SHEAR...WHICH
COULD POSSIBLY LEAD TO ISOLATED SEVERE HAIL (SEVERE HAIL POTENTIAL
IS DEPENDENT ON STRENGTH OF INSTABILITY). THIS COMPLEX WILL LIKELY
WEAKEN AS IT MOVES TO THE NORTH...BUT THUNDER/SHOWER CHANCES
SHOULD HOLD TOGETHER AND EXIT THE NORTHERN FA SATURDAY MORNING.
UPDATED THE GRIDS THROUGH TONIGHT FOR THIS THINKING (AND WILL
CONCENTRATE ON SATURDAY THROUGH MONDAY FOR THE NEXT FORECAST
ISSUANCE).
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 325 AM CDT FRI MAY 17 2013
FORECAST CHALLENGE CONCERNS PCPN CHANCES/AMOUNTS AND TEMPERATURES.
MODELS IN GENERAL AGREEMENT WITH MAIN FEATURES HOWEVER ALL DIFFER
ON QPF SCENARIOS THROUGH THE SHORT TERM. AT THIS POINT WILL USE A
GENERAL BLEND.
PERSISTENT BAND OF -SHRA ASSOCIATED WITH ELEVATED ZONE OF
ENHANCED WARM ADVECTION AND H7 CONVERGENCE SHOULD GRADUALLY WEAKEN
THROUGH THE MORNING AS ABOVE FEATURES WEAKEN AND SHIFT NE. WILL GO
WITH HIGH POP/LOW QPF INTO MID MORNING THEN TRIM BACK ON POPS.
ELSEWHERE CONFIDENCE LOW ON ANY PCPN POTENTIAL THROUGH THE BULK OF
THE DAY. SURFACE LOW AND E-W ORIENTED WARM FRONTAL BOUNDARY ALONG
SD/NE BORDER INTO IA LIFTS SLOWLY THROUGH SD DURING THE DAY.
EXPECT MOST PCPN WILL BE ORIENTED CLOSER TO LOW LEVEL BOUNDARY TO
OUR SOUTH. WILL INCREASE POPS SOMEWHAT LATER IN THE AFTERNOON AS
BOUNDARY APPROACHES. TEMPERATURES WILL BE HIGHLY INFLUENCED BY
CLOUDS. RAISED TEMPERATURES SLIGHTLY ACROSS THE SOUTH WHERE SOME
THINNER CLOUD COVER EXISTS OTHERWISE WILL STICK WITH PERSISTENCE.
AS WARM FRONT LIFTS NORTH TONIGHT EXPECT RAIN CHANCES TO INCREASE
AND BY MID EVENING SOUTHERN AND WESTERN FORECAST AREAS LOOK TO BE
FAVORED AREAS FOR SHRA/TSRA. BEST THUNDER POTENTIAL WILL BE ACROSS
THE SOUTH AS NORTHERN AREAS STILL PRETTY STABLE. BAND OF PCPN
SHOULD LIFT NORTHWARD OVERNIGHT NIGHT AND ADJUSTED POPS
ACCORDINGLY.
FRONTAL BOUNDARY WILL BE ORIENTED ACROSS FA SATURDAY SO INCREASED
POPS. SEVERE POTENTIAL LOOKS BEST LATE IN THE AFTERNOON ACROSS THE
SOUTH HALF OF THE FA WITH FAVORABLE CONVECTIVE PARAMETERS.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 AM CDT FRI MAY 17 2013
SEVERE CONVECTIVE THREAT WILL CONTINUE INTO THE EVENING. WITH
PRECIPITABLE H2O VALUES AROUND 1.5 INCHES HEAVY RAIN WILL BE A
POSSIBILITY. INITIALLY FAVORED AREA FOR HEAVY RAIN LOOKS TO BE
ACROSS S HALF OF FA LIFTING NORTHWARD DURING THE OVERNIGHT.
WITH CUT OFF LOW DEVELOPING VCNTY OF FA POTENTIAL FOR SIGNIFICANT
RAIN WILL CONTINUE THROUGH THE WEEKEND AND WILL NEED TO MONITOR
RAIN AMOUNTS CLOSELY. AT THIS POINT LONG DURATION RAIN EVENT FOR
SURE BUT NOT ENOUGH CONFIDENCE ON ANY PARTICULAR LOCATION FOR
FLOOD/FLASH FLOOD WATCH.
0 UTC GFS/ECMWF/GEM IN GOOD OVERALL AGREEMENT NEXT WEEK...SHOWING A
CLOSED 500 HPA LOW ACROSS SOUTHEAST SD MONDAY MORNING CRAWLING
PAINFULLY SLOW TO THE EAST THROUGH WEDNESDAY. THIS FIRMLY ENTRENCHES
THE FORECAST AREA IN WRAP-AROUND RAIN SHOWERS THROUGH TUESDAY...
SLOWLY DRYING OUT WEDNESDAY AND A RETURN TO DRY CONDITIONS ON THURSDAY.
WILL KEEP THUNDER MENTION THROUGH MONDAY...BUT MOST INSTABILITY
SHOULD MOVE TO THE SOUTH BY TUESDAY. WITH CLOUD COVER AND RAIN...
TEMPERATURES WILL BE NEAR OR SLIGHTLY BELOW MID-MAY NORMALS WITH
HIGHS IN THE UPPER 50S AND 60S AND LOWS IN THE 40S/LOWER 50S. WITH
GREATER SUNSHINE AND DRY CONDITIONS...SHOULD SEE SOME AREAS REACHING
70 DEGREES BY THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1243 PM CDT FRI MAY 17 2013
QUESTION FOR THIS PERIOD WILL BE HOW FAR NORTH THE MVFR CLOUDS
SPREAD DURING THE NIGHT INTO SATURDAY MORNING AND PRECIPITATION
(THUNDER) CHANCES. THRU 00Z FORSEE ALL SITES STAYING VFR..BUT
WATCHING AN AREA OF HIGHER DEW POINTS ALONG WITH 25-35K FT CLOUD
DECK MOVING SLOWLY NORTHWEST FROM WCNTRL MN AND ECNTRL SD. TIMING
OF THIS MOVEMENT NORTHWEST INTO FARGO AREA IS SUSPECT...BUT LATEST
RAP MODEL SUGGEST 03Z-06Z PERIOD. THESE CONDITIONS MAY REACH THE
OTHER TAF SITES TOWARD 12Z. PRECIP (THUNDER) CHANCES LATER TONIGHT
INTO SATURDAY MORNING AND WHEN/HOW IT AFFECTS ANY TAF SITE IS QUITE
DIFFICULT TO DETERMINE NOW. FOR NOW JUST INCLUDED A TEMPO GROUP FOR
FARGO AS BEST CHANCE APPEARS THERE OVERNIGHT. WINDS WILL REMAIN
SOUTHEAST MOSTLY 10 TO 20 KTS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...VOELKER
LONG TERM...VOELKER/ROGERS
AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
350 AM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT FRI MAY 17 2013
THE MAIN CONCERN FOR TODAY INTO TONIGHT WILL BE THE CHANCE OF
THUNDERSTORMS AND POTENTIAL SEVERE WEATHER. EARLY MORNING RADAR
MOSAIC SHOWED ISOLATED SHOWERS FROM SOUTHWEST NORTH DAKOTA INTO
NORTHWEST MINNESOTA. MUCH OF THIS ACTIVITY DEVELOPED IN AN AREA OF
H85 WARM AIR ADVECTION THAT HAS BEEN MOVING FROM SOUTH TO NORTH
ACROSS THE REGION. THE STRONGEST WARM AIR ADVECTION SHIFTS NORTH BY
AFTERNOON AS SOUTHWESTERLY FLOW ALOFT BRINGS A SERIES OF WAVES ACROSS
THE STATE. WILL MAINTAIN FAIRLY HIGH POPS TODAY...ESPECIALLY IN
THE NORTH AND WEST WHERE THE MAJORITY OF MODEL SOLUTIONS FAVOR THE
HIGHER PRECIPITATION CHANCES.
THE FOCUS THEN TURNS FARTHER SOUTH AS SURFACE LOW PRESSURE GATHERS
IN EAST CENTRAL WYOMING. A WARM FRONT STRETCHING OUT OF THE LOW
INTO SOUTHERN SOUTH DAKOTA IS EXPECTED TO LIFT NORTH TONIGHT...BRINGING
INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS TO CENTRAL AND
WESTERN NORTH DAKOTA. CAN NOT RULE OUT AN ISOLATED SEVERE STORM
LATE THIS AFTERNOON / EVENING ACROSS THE SOUTHERN PART OF THE
FORECAST AREA WHERE INSTABILITY WILL BE GREATEST. THE SPC DAY 1
SEVERE WEATHER OUTLOOK KEEPS THE SLIGHT RISK SOUTH OF THE FORECAST
AREA...HOWEVER THE 5 PERCENT PROBABILITIES FOR SEVERE HAIL / WIND
ARE DRAWN SOUTH OF I-94 INTO SOUTHERN NORTH DAKOTA WHICH APPEARS
REASONABLE.
TEMPERATURES TODAY WILL BE TRICKY DUE TO THE CLOUDS AND RAIN. WILL
GENERALLY STAY ON THE COOL SIDE OF GUIDANCE WHICH SUGGESTS MID
60S NORTH TO LOWER 70S SOUTH.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 349 AM CDT FRI MAY 17 2013
THE MAIN FORECAST ISSUES THROUGH THE LONG TERM PERIOD ARE CONVECTIVE
TRENDS...AND POTENTIAL FOR PROLONGED MODERATE TO HEAVY RAIN AND
SOME SEVERE WEATHER ON SATURDAY. THE LATEST 17/00Z MODEL RUNS HAVE
SOME SIGNIFICANT DIFFERENCE IN THE PROGRESSION OF A CLOSED UPPER
LOW THROUGH THE REGION THROUGH EARLY NEXT WEEK. THE NAM IS AMONG
THE FARTHEST WEST...WHILE THE GFS FAVORS A FASTER...MORE EASTERLY
PATH. THE ECMWF REPRESENTS A REASONABLE COMPROMISE...AND WOULD
KEEP SHOWERS AROUND INTO TUESDAY BEFORE PUSHING EAST. THE FAVORED
PERIOD FOR SEVERE WEATHER WILL BE SATURDAY...WITH SOUTHWEST FLOW
ALOFT AND A WARM FRONT NOSING INTO THE SOUTHEAST PORTION OF THE
FORECAST AREA. SPC CONTINUES TO HAVE THE SOUTHEAST OUTLOOKED IN
SLIGHT RISK FOR DAY 2. BUFR SOUNDINGS SUGGEST STORMS WILL DEVELOP
RELATIVELY EARLY IN THE DAY. AM EXPECTING SOME STRONG TO SEVERE
STORMS WITH LARGE HAIL/STRONG WIND GUSTS THE PRIMARY THREATS.
STRONG MOISTURE TRANSPORT INTO THE BOUNDARY WILL CONTINUE THROUGH
SATURDAY NIGHT AS A DECENT SHORT WAVE TROUGH MOVES THROUGH EASTERN
NORTH DAKOTA. THE SEVERE WEATHER THREAT DIMINISHES SUNDAY...BUT
MODERATE TO LOCALLY HEAVY RAIN IS EXPECTED TO CONTINUE OVER MUCH
OF WESTERN AND CENTRAL NORTH DAKOTA. THIS SCENARIO WILL LIKELY
CONTINUE MONDAY...BEFORE SHOWERS TAPER OFF IN COVERAGE AND
INTENSITY ON TUESDAY. TOTAL RAINFALL AMOUNTS OF 1 TO 3 ARE
EXPECTED THROUGH THE PERIOD...WITH AMOUNTS AROUND 4 INCHES
POSSIBLE...ESPECIALLY IN THE JAMES RIVER VALLEY. CONDITIONS ARE
SUCH THAT SOILS CAN ABSORB SIGNIFICANT RAINFALL. THUS...SIGNIFICANT
RISES ON MAIN STEM RIVERS SUCH AS THE SOURIS AND JAMES ARE NOT
EXPECTED. HOWEVER...ENHANCED RAINFALL RATES OR SEVERAL ROUNDS OF
STORMS COULD PRODUCE LOCALIZED RUNOFF...LEADING TO RISES ON SMALL
CREEKS AND STREAMS...AND POSSIBLY FLASH FLOODING.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1244 AM CDT FRI MAY 17 2013
MVFR / IFR CEILINGS CONTINUE TO SPREAD INTO PARTS OF CENTRAL AND
WESTERN NORTH DAKOTA EARLY THIS MORNING. THE WESTERN PART OF THE
STATE APPEARS FAVORED FOR THE LOWEST CEILINGS WITH THE 17.00Z NAM
SHOWING THE BEST LOW LEVEL SATURATION IN THAT REGION.
RAIN CHANCES REMAIN DIFFICULT TO PINPOINT WITH ENOUGH SPREAD IN
MODEL SOLUTIONS TO KEEP CONFIDENCE FAIRLY LOW IN SPECIFIC TIMING.
THE 17.03Z RAP STILL FAVORS THE NORTH THIS MORNING IN AN AREA OF
H85 WARM AIR ADVECTION. THIS IS GENERALLY IN LINE WITH CURRENT
RADAR TRENDS...SO WILL CONFINE ANY SHOWERS THIS MORNING TO KMOT
AND KISN.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM/AVIATION...CK
LONG TERM...RP KINNEY
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1246 AM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 1244 AM CDT FRI MAY 17 2013
REGIONAL RADAR MOSAIC SHOWS ISOLATED TO SCATTERED SHOWERS ACROSS
NORTH CENTRAL AND NORTHEAST NORTH DAKOTA. THIS APPEARS TO LINE UP
WITH AN AREA OF H85 WARM AIR ADVECTION SHOWN BY THE 17.03Z RAP.
THE STRONGEST WARM AIR ADVECTION IS FORECAST TO BE ACROSS NORTHERN
PARTS OF THE STATE EARLY THIS MORNING...SO WILL HAVE THE HIGHEST
POPS IN THAT REGION. INSTABILITY REMAINS LIMITED THIS
MORNING...SO ANY THUNDER CHANCES SHOULD BE ISOLATED AT BEST.
UPDATE ISSUED AT 1016 PM CDT THU MAY 16 2013
ADJUSTED EVENING POPS DOWNWARD BASED ON CURRENT RADAR OBS/TRENDS.
OTHERWISE...NOT TOO MANY CHANGES WERE MADE TO THE ONGOING
FORECAST. THE UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 718 PM CDT THU MAY 16 2013
REGIONAL RADAR TRENDS INDICATE NUMEROUS SHOWERS ACROSS THE JAMES
RIVER BASIN CONTINUING TO PUSH EAST OF THE CWA THIS EVENING. WITH
THE ATMOSPHERE PRETTY WELL WORKED OVER...DECREASED POPS WEST AND
CENTRAL THROUGH THE REMAINDER OF THE EVENING HOURS.
HOWEVER...SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG INCREASING PRECIP
CHANCES AFTER MIDNIGHT AS AN UPPER WAVE APPROACHES FROM THE
SOUTHWEST. SHOWALTER INDICES INDICATE THUNDER POTENTIAL DEVELOPING
ACROSS SOUTHWESTERN NORTH DAKOTA AFTER MIDNIGHT. AS A
RESULT...REMOVED THUNDER AREAWIDE TONIGHT AND ONLY INDICATED
ISOLATED THUNDER SOUTHWEST DEVELOPING AFTER MIDNIGHT.
UPDATED THE HOURLY SENSIBLE WEATHER GRIDS BASED ON CURRENT
OBS/TRENDS. THE UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 300 PM CDT THU MAY 16 2013
LATEST WATER VAPOR IMAGERY SHOWS A SOUTHWEST FLOW INTO NORTH DAKOTA
AHEAD OF AN UPPER TROUGH WHICH IS SLIDING INTO THE NORTHWEST COAST.
FOR THE NEAR TERM...THROUGH THURSDAY EVENING...CATEGORICAL POPS
WILL CONTINUE FROM BLAT TO MCCLUSKY INTO BISMARCK AND AREAS TO
THE EAST AS A SHORTWAVE PROPAGATES THROUGH. THERE IS A BREAK IN
THE CLOUDS AND PRECIPITATION IN THE FAR WEST WITH MORE SHORTWAVES
MOVING INTO CENTRAL MONTANA. THESE WILL MOVE THROUGH TONIGHT INTO
FRIDAY GENERATING ISOLATED TO SCATTERED SHOWERS. BEST CHANCE FOR
AN ISOLATED THUNDERSTORM WILL RESIDE IN THE WEST AND SOUTH INTO
TONIGHT. LATEST VISIBLE IMAGERY SHOWS SOME CLEARING IN THE WEST
WITH CLOUDS BEGINNING TO BILLOW UP IN NORTHEAST MONTANA. FOR
FRIDAY...SOME INSTABILITY CONTINUES IN THE SOUTHWEST AND FAR SOUTH
CENTRAL FOR A MENTION OF THUNDERSTORMS...OTHERWISE SCATTERED
SHOWERS WILL GENERALLY BE THE RULE.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 300 PM CDT THU MAY 16 2013
A BROADENING UPPER LEVEL LOW POSITIONED OVER THE WESTERN CONUS EARLY
THE EXTENDED WILL ALLOW FOR MOIST SOUTHWESTERLY FLOW TO CONTINUE
ACROSS THE NORTHERN PLAINS SATURDAY INTO SUNDAY. AS THIS BROAD UPPER
LEVEL TROUGH SLOWLY SHIFTS EAST AND OVER THE REGION LATE SUNDAY AND
EARLY MONDAY THE FLOW WILL BECOME SOUTHERLY AS THE UPPER LEVEL
TROUGH CLOSES OFF OVER THE DAKOTAS. IT WILL REMAIN OVERHEAD MONDAY
AND TUESDAY BEFORE MOVING EAST THEREAFTER. 12Z GFS/GEM/NAM/ECWMF ARE
IN GOOD AGREEMENT REGARDING THIS PATTERN...BEFORE SOLUTIONS DIVERGE
LATE IN THE EXTENDED AS THE UPPER LEVEL LOW MOVES EAST.
THE MAIN ISSUE FOR THE EXTENDED WILL BE THE POTENTIAL FOR HEAVY RAIN
THROUGH EARLY NEXT WEEK. THERE IS DECENT AGREEMENT BETWEEN THE 12Z
MODEL RUNS REGARDING THE PLACEMENT AND AMOUNT OF PRECIPITATION
ACROSS THE AREA...WITH THE HEAVIEST AMOUNTS FOCUSED ON THE JAMES
RIVER VALLEY AND POINTS EAST. A SECOND AREA OF HEAVY PRECIPITATION
MAY BE POSSIBLE ACROSS THE NORTHWEST. HOWEVER...THERE IS A BIT
MORE UNCERTAINTY FOR THE NORTHWEST AREA. IN ADDITION...THE 12Z
GFS AND NAM CONTINUE TO PLACE PRECIPITABLE WATER VALUES OF 1.30 TO
1.50 INCHES ACROSS THE EASTERN TWO THIRDS OF NORTH DAKOTA SATURDAY
THROUGH EARLY SUNDAY MORNING. ACCORDING TO PW CLIMATOLOGY...THESE
FORECAST VALUES WILL BE IN THE 99TH PERCENTILE TO THE HIGHEST EVER
OBSERVED FOR THE MONTH OF MAY. CONFIDENCE IS INCREASING FOR 1 TO 2
INCHES (WITH LOCALLY HIGHER AMOUNTS ACROSS THE JAMES RIVER VALLEY)
OF RAINFALL THROUGH SUNDAY EVENING. ADDITIONAL LIGHT TO MODERATE
RAIN WILL CONTINUE THROUGH TUESDAY AS THE UPPER LEVEL LOW IS
OVERHEAD...BRINGING POTENTIAL RAINFALL TOTALS THROUGH TUESDAY INTO
THE 2 TO 4 INCH RANGE. THIS WILL HAVE TO BE MONITORED CLOSELY OVER
THE NEXT FEW DAYS AS POTENTIAL HYDRO ISSUES FOR THE JAMES RIVER
MAY COME INTO PLAY. ALSO...THIS HEAVY RAIN EVENT WILL POTENTIALLY
ALLEVIATE THE RAINFALL DEFICITS OBSERVED SO FAR FOR MAY.
REGARDING THE POTENTIAL FOR SEVERE WEATHER...THE BEST CHANCES FOR
ANY SEVERE WEATHER WILL COME SATURDAY AFTERNOON THROUGH EARLY SUNDAY
MORNING FOR LOCATIONS EAST OF STATE HIGHWAY 83 AND SOUTH OF
INTERSTATE 94. ISOLATED SEVERE MAY BE POSSIBLE FOR THE SOUTHWEST
LATE SATURDAY AFTERNOON AND EARLY EVENING. SUFFICIENT MOISTURE
WILL BE PRESENT DUE TO PREVIOUS MOISTURE RECEIVED ON THURSDAY AND
FRIDAY. BULK SHEAR VALUES WILL BE IN THE 40 TO 50 KT RANGE DURING
THIS PERIOD...WITH ML CAPE IN THE 1000 TO 2000 J/KG RANGE FOR THE
FAR SOUTH CENTRAL...AND 2000 TO 3000 J/LG VALUES ACROSS THE
SOUTHERN JAMES RIVER VALLEY. MU CAPE VALUES WILL BE IN THE 1200 TO
3000 J/KG RANGE AS WELL. HOWEVER...THE MAIN LIMITING FACTOR WILL
BE THE WARM AIR ALOFT...AS THE NAM/GFS BUFR SOUNDINGS FOR JMS/BIS
DEPICT A DECENT CAP INVERSION. THIS MAY BE OVERCOME BY DAYTIME
HEATING AND LARGE SCALE ASCENT ASSOCIATED WITH THE AFOREMENTIONED
UPPER LEVEL TROUGH.
BEYOND TUESDAY...THE UPPER LEVEL LOW WILL MOVE EAST AND IN ITS
WAKE...UPPER LEVEL RIDING WILL COMMENCE. A PERIOD OF DRIER AND
SEASONABLE TEMPERATURES ARE FORECAST FOR WEDNESDAY AND THURSDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1244 AM CDT FRI MAY 17 2013
MVFR / IFR CEILINGS CONTINUE TO SPREAD INTO PARTS OF CENTRAL AND
WESTERN NORTH DAKOTA EARLY THIS MORNING. THE WESTERN PART OF THE
STATE APPEARS FAVORED FOR THE LOWEST CEILINGS WITH THE 17.00Z NAM
SHOWING THE BEST LOW LEVEL SATURATION IN THAT REGION.
RAIN CHANCES REMAIN DIFFICULT TO PINPOINT WITH ENOUGH SPREAD IN
MODEL SOLUTIONS TO KEEP CONFIDENCE FAIRLY LOW IN SPECIFIC TIMING.
THE 17.03Z RAP STILL FAVORS THE NORTH THIS MORNING IN AN AREA OF
H85 WARM AIR ADVECTION. THIS IS GENERALLY IN LINE WITH CURRENT
RADAR TRENDS...SO WILL CONFINE ANY SHOWERS THIS MORNING TO KMOT
AND KISN.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...KS
LONG TERM...LTH
AVIATION...CK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1150 PM CDT THU MAY 16 2013
.UPDATE...
ISSUED AT 1150 PM CDT THU MAY 16 2013
BAND OF PRECIP ALONG HIGHWAY 2 HAS BEGUN TO DIMINISH AS 700MB
FRONTOGENESIS HAS DECREASED. TRENDED DOWNWARD SLOWLY WITH POPS
OVER THAT AREA FOR THE REST OF THE NIGHT. PRECIP TO OUR SOUTH HAS
STAYED WELL CLEAR OF OUR SOUTHEASTERN BORDERS...SO LOWERED POPS
UNTIL LATER IN THE DAY TOMORROW. MADE A FEW MINOR TWEAKS TO TEMPS
AND WINDS.
UPDATE ISSUED AT 937 PM CDT THU MAY 16 2013
SFC HIGH PRESSURE OVER ONTARIO AND A DEVELOPING LOW OVER CO/WY
CONTINUES TO BRING NORTHEASTERLY WINDS THAT WILL SLOWLY SHIFT
AROUND TO THE EAST LATER TONIGHT. STILL THINK THAT OUR LIGHT RAIN
ALONG THE HIGHWAY 2 CORRIDOR WILL SLOWLY DIMINISH AS CONVECTION
RAMPS UP FURTHER SOUTH. HOWEVER...PRECIP HAS MOVED A BIT FURTHER
EAST THAN EARLIER EXPECTATIONS SO ADJUSTED POPS/WX ACCORDINGLY.
KEPT LIKELIES GOING FOR THE REST OF THE EVENING AND THEN STARTED
TO DROP THEM DOWN LATER TONIGHT.
UPDATE ISSUED AT 646 PM CDT THU MAY 16 2013
BAND OF LIGHT RAIN CONTINUES FROM NEAR DEVILS LAKE TO THE CENTRAL
RED RIVER VALLEY INTO NORTHWESTERN MINNESOTA...WITH SPRINKLES
ELSEWHERE. THE NAM AND RAP ARE IN PRETTY GOOD AGREEMENT ON THIS
ACTIVITY DIMINISHING LATER THIS EVENING AS THE COMPLEX OVER SD/MN
GETS GOING AND ROBS MOISTURE. KEPT HIGH POPS IN THE NORTH THIS
EVENING BEFORE TRANSITIONING TO BETTER PERCENTAGES IN THE SOUTH
LATER ON TONIGHT. LOWERED TEMPS A BIT IN THE NORTHWEST AS READINGS
HAVE ALREADY DROPPED INTO THE LOWER 50S AND THERE COULD BE SOME
BREAKS IN THE CLOUDS LATER TONIGHT TO ALLOW IT TO GET DOWN INTO
THE UPPER 40S.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 120 PM CDT THU MAY 16 2013
THE MAIN CHALLENGE WILL BE UPCOMING PROLONGED WET PATTERN TONIGHT
INTO THE MIDDLE OF NEXT WEEK. MODELS ARE IN GOOD OVERALL AGREEMENT
INITIALLY...WITH SOME DIFFERENCES BY NEXT WEEK. THE NAM/GFS ARE A
GOOD COMPROMISE IN THE NEAR TERM.
FOR TONIGHT...THERE WILL BE AN AREA OF SHOWERS MOVING FROM WEST TO
EAST ACROSS THE AREA. THIS BAND OF SHOWERS IS BEING AIDED BY
STRONG MID LEVEL OMEGA AND UPPER LEVEL DIVERGENCE...AS PWATS
INCREASE TO AROUND 1 INCH. THERE SHOULD BE A BAND OF STRONGER
CONVECTION SOUTH OF THE AREA OVERNIGHT...THAT SHOULD ROB THE
DEEPER MOISTURE FROM OUR AREA. WE WILL INCREASE POPS THIS EVENING
IN THE WEST INTO THE CENTRAL RED RIVER VALLEY WITH STRONGER ECHOES
MOVING INTO THE AREA.
FOR FRIDAY...WE SHOULD GET A BREAK IN THE LARGER SCALE SHOWERS
WITH EASTERLY FLOW NEAR THE SFC INCREASING. WE WILL MAINTAIN A LOW
CHANCE FOR SHOWERS THOUGH WITH PLENTY OF CLOUDS AND POSSIBLY A
SUBTLE SHORTWAVE MOVING THROUGH.
FOR FRIDAY NIGHT...A LLJ WILL DEVELOP IN SD AND MOVE INTO THE
SOUTH OVERNIGHT EXPECT AN AREA OF SHOWERS AND THUNDERSTORMS TO
MOVE INTO THE AREA...WITH THE BEST CHANCE FOR THUNDER IN THE
SOUTH. THERE WILL BE SOME ELEVATED INSTABILITY WITH 850MB CAPE
AROUND 1000 J/KG...SO A STRONG TO LOCALLY SEVERE STORM IS POSSIBLE.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 310 PM CDT THU MAY 16 2013
FOR SATURDAY THROUGH SUNDAY...A VERY ACTIVE WEATHER PATTERN IS
EXPECTED. SHOWERS AND STORMS SHOULD BE ONGOING AT LEAST IN THE
SOUTH SATURDAY MORNING. BY SATURDAY AFTERNOON AND EVENING...DEEP
MOISTURE AND STRONG INSTABILITY SHOULD DEVELOP OVER SE ND...NEAR
THE EDGE OF A STRONG CAPPING INVERSION. MLCAPES ARE PROGGED OVER
4000 J/KG INTO NC SD...AND AROUND 3000 J/KG IN SE ND. EXPECT
STORMS TO DEVELOP QUICKLY IN SD ONCE THE CAP BREAKS...AND MOVE
NORTH AND EAST INTO THE AREA SATURDAY NIGHT AND SUNDAY. SOME
STORMS COULD BE SEVERE SATURDAY NIGHT INTO SUNDAY...BUT LOCALLY
HEAVY RAIN IS POSSIBLE WITH PWATS RISING TO AROUND 1.5 INCHES OR
EVEN A BIT HIGHER. WE HAVE ISSUED AN ESF FOR SOME LOCALIZED
FLOODING POSSIBLE IF TRAINING ECHOES OCCUR WITH A PARALLEL UPPER
BOUNDARY.
SAME SCENARIO IN PLACE FOR EXTENDED...AFTER A WEEKEND OF RAIN AND
THUNDERSTORMS...UPPER LOW LIKELY TO BE LOCATED OVER AN AREA ANYWHERE
FROM SOUTHEAST NORTH DAKOTA TO IOWA. MOISTURE WILL STILL BE
TRANSPORTED CYCLONICALLY AROUND THIS STACKED SYSTEM CONTINUING
SHOWERS WITH THE POSSIBILITY OF SOME THUNDER. ORIENTATION OF
BOUNDARY AND ASSOCIATED CONVECTIVE PARAMETERS MAKE MONDAY THE MORE
LIKELY TIME FOR THUNDER ACTIVITY...LESS SO ON TUESDAY AND BY
WEDNESDAY PRECIPITATION SHOULD BE MORE SHOWERY OR EVEN JUST SOME
STRATIFORM RAIN. GOING POP FREE FINALLY BY THURSDAY AS AN OMEGA
BLOCK DEVELOPS WITH NORTHERN PLAINS UNDER THE RIDGE PART OF THE
BLOCK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1150 PM CDT THU MAY 16 2013
VFR CONDITIONS AND SLOWLY DIMINISHING LIGHT RA OVER
KDVL...KGFK...AND KTVF WILL CONTINUE FOR THE REST OF THE NIGHT.
SOME MVFR CONDITIONS WILL BE POSSIBLE AT KDVL AND POSSIBLY FURTHER
EAST. WINDS WILL STAY EAST AROUND 10 KTS.
&&
.HYDROLOGY...
ISSUED AT 310 PM CDT THU MAY 16 2013
THE NORTHERN PORTION OF THE RED RIVER CONTINUES TO SEE RIVER LEVELS
UNDERGO RECESSION AT DRAYTON AND PEMBINA. THIS IS THE LAST REMNANT
OF THE SNOWMELT WATER SURGE CONTINUING TO MOVE NORTHWARD INTO
CANADA.
A PROLONGED PERIOD OF UNSETTLED WEATHER IS EXPECTED TO BEGIN THIS
EVENING AND CONTINUE THROUGH TUESDAY. CUMULATIVE RAINFALL TOTALS OF
2 TO 4 INCHES ACROSS THE RED RIVER BASIN...WITH LOCALLY HIGHER
AMOUNTS...WILL BE POSSIBLE BY TUESDAY MORNING. LOCALIZED FLASH
FLOODING IS A POSSIBILITY OVER THE WEEKEND DUE TO TRAINING
THUNDERSTORMS. IN ADDITION...DESPITE SOME RAINFALL INFILTRATION
DUE TO PATCHY DRY TOPSOIL...ENOUGH RUNOFF MAY OCCUR TO CAUSE SOME
SMALLER TRIBUTARIES TO RISE BACK ABOVE FLOOD STAGE NEXT WEEK. AS A
RESULT...A HYDROLOGIC OUTLOOK HAS BEEN ISSUED TO HIGHLIGHT THE
SITUATION.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...DK
LONG TERM...WJB/DK
AVIATION...JR
HYDROLOGY...BRAMER
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
953 PM EDT SAT MAY 18 2013
.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND WILL MAINTAIN A RIDGE OVER THE
EASTERN GREAT LAKES INTO SUNDAY BEFORE SHIFTING OFF THE COAST. MEANWHILE
A NEARLY STATIONARY FRONT ACROSS SOUTHERN OHIO WILL LIFT BACK NORTH
LATE SUNDAY. SOUTHERLY FLOW WILL BRING MORE HUMID AIR EARLY IN THE
WEEK AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. THE FRONT
SHOULD ARRIVE LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
ADJUSTED CLOUDS AND HOURLY TEMPS A BIT BUT NO MAJOR CHANGES TO
FORECAST FOR THE UPDATE.
PREVIOUS...LIGHT SHOWERS CONTINUE TO DIMINISH ACROSS NORTH
CENTRAL OHIO AND SPC RUC ANALYSIS SHOWS INSTABILITY LIMITED TO
SOUTHERN OHIO. SATELLITE AND RADAR IMAGERY SUPPORT THAT WITH
SHOWERS DEVELOPING CLOSER TO THE OHIO RIVER. THE FORECAST THROUGH
THE REMAINDER OF THE EVENING WILL ONLY CARRY A CHANCE OF SPRINKLES
SOUTH OF A FDY-MFD-CAK LINE. OTHERWISE EXPECT CLOUD COVER TO
GRADUALLY DIMINISH THROUGH LATE EVENING...WITH SOME INCREASE
POSSIBLE FROM THE SOUTH LATE TONIGHT. TEMPERATURES WILL BOTTOM OUT
IN THE UPPER 50S TO NEAR 60 DEGREES.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
WEAK UPPER LEVEL DISTURBANCE SLOWLY SHIFTS TO THE EAST COAST THROUGH
SUNDAY NIGHT. MODELS SHOW THE STALLED FRONTAL BOUNDARY OVER THE OHIO
VALLEY SHIFTING BACK NORTH LATE SUNDAY WHICH WILL ALLOW LOW LEVEL
MOISTURE TO INCREASE. STILL NO OBVIOUS FORCING MECHANISM ON SUNDAY
AFTERNOON TO KICK OFF SHOWERS AND THUNDERSTORMS BENEATH THE BUILDING
RIDGE ALOFT SO WILL CONTINUE TO HOLD ONTO FAIRLY LOW POPS...WITH
BEST CHANCES FOCUSED SOUTH OF A FDY-YNG LINE. EXPECTING A LITTLE
LESS CLOUD COVER...ESPECIALLY IN NW OHIO WITH HIGHS RANGING FROM THE
UPPER 70S TO LOW 80S. ALTHOUGH MODELS ARE DRY ON SUNDAY NIGHT...HAVE
ADDED IN A LOW POP TO NW OHIO AS THETA E RIDGE LIFTS NORTH INTO THE
AREA. MODELS OFTEN STRUGGLE WITH DETECTING NOCTURNAL SHOWERS IN THIS
PATTERN AND NAM SOUNDINGS SHOW A FAIR AMOUNT OF ELEVATED INSTABILITY
TO WORK WITH. WILL CONTINUE THIS SLIGHT CHANCE EASTWARD ACROSS THE
AREA THROUGH MONDAY MORNING.
UPPER LEVEL LOW WILL DEVELOP OVER THE PLAINS ON SUNDAY AND SLOWLY
PUSH EASTWARD DURING THE EARLY PART OF NEXT WEEK. DEEP SOUTHERLY
FLOW WILL RESULT IN A MOISTENING AIRMASS WITH INCREASING CHANCES OF
SHOWERS AND THUNDERSTORMS. WITH THE RIDGE OVERHEAD...SLOWLY SHIFTING
EAST OF THE AREA...THE BETTER CHANCES OF SHOWERS AND THUNDERSTORMS
WILL BE ACROSS NORTHERN PORTIONS OF THE FORECAST AREA AS ENERGY
EJECTS OUT OF THE TROUGH AND TRIES TO MOVE AROUND THE RIDGE. MONDAY
WILL LIKELY BE CAPPED FOR MOST AREAS WITH CHANCES INCREASING ON
TUESDAY. TEMPERATURES WARM INTO THE MID 70S ON MONDAY...THEN DROP
BACK INTO THE LOW 80S ON TUESDAY AS CLOUDS AND THUNDERSTORMS
INCREASE. LOWS WILL BE MILD AS DEWPOINTS CREEP UP...DROPPING INTO
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
COMPLEX WEATHER PATTERN CONTINUES FOR THE EXTENDED PERIOD. THE
MODELS CONTINUE TO SHOW A SLOW MOVING STORM SYSTEM JUST TO THE WEST
OF THE FORECAST AREA. IT APPEARS MUCH OF THE FORECAST AREA WILL BE
IN THE WARM SECTOR IN ADVANCE OF THE STORM AS IT MOVES EAST. THE
UPPER LEVEL SHORT WAVE WILL MOVE ACROSS THE REGION WEDNESDAY NIGHT
INTO THURSDAY. THE 12Z RUN OF THE GFS IS SLOWER WITH THE
PROGRESSION OF THIS STORM THAN IT WAS YESTERDAY. THE BEST LIFT FROM
THE SURFACE FRONT AND UPPER LEVEL LOW APPEARED TO BE MORE ON
WEDNESDAY YESTERDAY AND IT LOOKS MORE LIKE WEDNESDAY NIGHT AND
THURSDAY WITH THIS RUN. IN EITHER CASE...THE MIDDLE PART OF NEXT
WEEK WILL BE UNSETTLED WITH SCATTERED STORMS THROUGHOUT. THE SLOWER
PROGRESSION OF THIS MODEL RUN WILL FORCE ME TO PUT SHOWERS IN THE
FORECAST THROUGH THE END OF NEXT WEEK.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
EXPECT VFR CONDITIONS TO CONTINUE FOR THIS EVENING. DEW POINTS
CREEPING UP A BIT COULD SEE MVFR BR TOWARD DAYBREAK FOR A COUPLE
OF HOURS.
APPEARS TO BE A BETTER CHANCE OF SCATTERED AFTERNOON THUNDERSTORMS
SUNDAY AFTERNOON THAN TODAY. BEST CHANCE SHOULD BE SOUTH OF A YNG
TO FDY LINE. THAT SAID ONLY WENT VCTS FOR SOUTHERN TAF SITES
BECAUSE LOW CONFIDENCE AS TO WHERE THE FRONT WILL ACTUALLY SET UP
TOMORROW AFTERNOON. MODELS HAVE NOT HAD A GOOD HANDLE ON THE
MOVEMENT OF THE FRONT STALLED ACROSS SOUTHERN OHIO PAST FEW DAYS.
EVEN THOUGH CAPES TOMORROW AFTERNOON FORECAST TO BE IN 1000-1500
J/KG RANGE WILL STILL HAVE STRONG RIDGE OVER THE AREA.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS MONDAY
EVENING THROUGH WEDNESDAY.
&&
.MARINE...
EAST TO NORTHEAST WINDS CONTINUE OVER THE LAKE THIS AFTERNOON. A
FEW LOCATIONS REPORTING WIND SPEEDS IN THE 15 TO 20 KNOT RANGE.
THESE CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE EARLY EVENING
HOURS. THE 12Z BUFKIT RUN SHOWS A POCKET OF 20 TO 30 KNOT WINDS
WITHIN 1KFT OF THE SURFACE OVER THE WESTERN BASIN THROUGH 00Z. WITH
THE EAST TO NORTHEAST FETCH WAVE HEIGHTS COULD REACH 3 TO 5 FEET
OVER THE WEST. EVEN THOUGH THE CONDITIONS ARE MARGINAL...I WILL
CONTINUE THE SMALL CRAFT ADVISORY THROUGH THE EVENING. WINDS WILL
DECREASE OVERNIGHT TO 10 TO 15 KNOTS. A SIMILAR PATTERN WILL SETUP
ON SUNDAY BUT THE PRESSURE GRADIENT SHOULD BE WEAKER AND THEREFORE
THE WINDS NOT AS STRONG. I DO NOT ANTICIPATE SMALL CRAFT CRITERIA
FOR SUNDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC/TK
SHORT TERM...KEC
LONG TERM...GARNET
AVIATION...DJB
MARINE...GARNET
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
717 PM EDT SAT MAY 18 2013
.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND WILL MAINTAIN A RIDGE OVER THE
EASTERN GREAT LAKES INTO SUNDAY BEFORE SHIFTING OFF THE COAST. MEANWHILE
A NEARLY STATIONARY FRONT ACROSS SOUTHERN OHIO WILL LIFT BACK NORTH
LATE SUNDAY. SOUTHERLY FLOW WILL BRING MORE HUMID AIR EARLY IN THE
WEEK AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. THE FRONT
SHOULD ARRIVE LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
NO SIGNIFICANT CHANGES TO FORECAST FOR THE UPDATE.
PREVIOUS...LIGHT SHOWERS CONTINUE TO DIMINISH ACROSS NORTH
CENTRAL OHIO AND SPC RUC ANALYSIS SHOWS INSTABILITY LIMITED TO
SOUTHERN OHIO. SATELLITE AND RADAR IMAGERY SUPPORT THAT WITH
SHOWERS DEVELOPING CLOSER TO THE OHIO RIVER. THE FORECAST THROUGH
THE REMAINDER OF THE EVENING WILL ONLY CARRY A CHANCE OF SPRINKLES
SOUTH OF A FDY-MFD-CAK LINE. OTHERWISE EXPECT CLOUD COVER TO
GRADUALLY DIMINISH THROUGH LATE EVENING...WITH SOME INCREASE
POSSIBLE FROM THE SOUTH LATE TONIGHT. TEMPERATURES WILL BOTTOM OUT
IN THE UPPER 50S TO NEAR 60 DEGREES.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
WEAK UPPER LEVEL DISTURBANCE SLOWLY SHIFTS TO THE EAST COAST THROUGH
SUNDAY NIGHT. MODELS SHOW THE STALLED FRONTAL BOUNDARY OVER THE OHIO
VALLEY SHIFTING BACK NORTH LATE SUNDAY WHICH WILL ALLOW LOW LEVEL
MOISTURE TO INCREASE. STILL NO OBVIOUS FORCING MECHANISM ON SUNDAY
AFTERNOON TO KICK OFF SHOWERS AND THUNDERSTORMS BENEATH THE BUILDING
RIDGE ALOFT SO WILL CONTINUE TO HOLD ONTO FAIRLY LOW POPS...WITH
BEST CHANCES FOCUSED SOUTH OF A FDY-YNG LINE. EXPECTING A LITTLE
LESS CLOUD COVER...ESPECIALLY IN NW OHIO WITH HIGHS RANGING FROM THE
UPPER 70S TO LOW 80S. ALTHOUGH MODELS ARE DRY ON SUNDAY NIGHT...HAVE
ADDED IN A LOW POP TO NW OHIO AS THETA E RIDGE LIFTS NORTH INTO THE
AREA. MODELS OFTEN STRUGGLE WITH DETECTING NOCTURNAL SHOWERS IN THIS
PATTERN AND NAM SOUNDINGS SHOW A FAIR AMOUNT OF ELEVATED INSTABILITY
TO WORK WITH. WILL CONTINUE THIS SLIGHT CHANCE EASTWARD ACROSS THE
AREA THROUGH MONDAY MORNING.
UPPER LEVEL LOW WILL DEVELOP OVER THE PLAINS ON SUNDAY AND SLOWLY
PUSH EASTWARD DURING THE EARLY PART OF NEXT WEEK. DEEP SOUTHERLY
FLOW WILL RESULT IN A MOISTENING AIRMASS WITH INCREASING CHANCES OF
SHOWERS AND THUNDERSTORMS. WITH THE RIDGE OVERHEAD...SLOWLY SHIFTING
EAST OF THE AREA...THE BETTER CHANCES OF SHOWERS AND THUNDERSTORMS
WILL BE ACROSS NORTHERN PORTIONS OF THE FORECAST AREA AS ENERGY
EJECTS OUT OF THE TROUGH AND TRIES TO MOVE AROUND THE RIDGE. MONDAY
WILL LIKELY BE CAPPED FOR MOST AREAS WITH CHANCES INCREASING ON
TUESDAY. TEMPERATURES WARM INTO THE MID 70S ON MONDAY...THEN DROP
BACK INTO THE LOW 80S ON TUESDAY AS CLOUDS AND THUNDERSTORMS
INCREASE. LOWS WILL BE MILD AS DEWPOINTS CREEP UP...DROPPING INTO
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
COMPLEX WEATHER PATTERN CONTINUES FOR THE EXTENDED PERIOD. THE
MODELS CONTINUE TO SHOW A SLOW MOVING STORM SYSTEM JUST TO THE WEST
OF THE FORECAST AREA. IT APPEARS MUCH OF THE FORECAST AREA WILL BE
IN THE WARM SECTOR IN ADVANCE OF THE STORM AS IT MOVES EAST. THE
UPPER LEVEL SHORT WAVE WILL MOVE ACROSS THE REGION WEDNESDAY NIGHT
INTO THURSDAY. THE 12Z RUN OF THE GFS IS SLOWER WITH THE
PROGRESSION OF THIS STORM THAN IT WAS YESTERDAY. THE BEST LIFT FROM
THE SURFACE FRONT AND UPPER LEVEL LOW APPEARED TO BE MORE ON
WEDNESDAY YESTERDAY AND IT LOOKS MORE LIKE WEDNESDAY NIGHT AND
THURSDAY WITH THIS RUN. IN EITHER CASE...THE MIDDLE PART OF NEXT
WEEK WILL BE UNSETTLED WITH SCATTERED STORMS THROUGHOUT. THE SLOWER
PROGRESSION OF THIS MODEL RUN WILL FORCE ME TO PUT SHOWERS IN THE
FORECAST THROUGH THE END OF NEXT WEEK.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
EXPECT VFR CONDITIONS TO CONTINUE FOR THIS EVENING. DEW POINTS
CREEPING UP A BIT COULD SEE MVFR BR TOWARD DAYBREAK FOR A COUPLE
OF HOURS.
APPEARS TO BE A BETTER CHANCE OF SCATTERED AFTERNOON THUNDERSTORMS
SUNDAY AFTERNOON THAN TODAY. BEST CHANCE SHOULD BE SOUTH OF A YNG
TO FDY LINE. THAT SAID ONLY WENT VCTS FOR SOUTHERN TAF SITES
BECAUSE LOW CONFIDENCE AS TO WHERE THE FRONT WILL ACTUALLY SET UP
TOMORROW AFTERNOON. MODELS HAVE NOT HAD A GOOD HANDLE ON THE
MOVEMENT OF THE FRONT STALLED ACROSS SOUTHERN OHIO PAST FEW DAYS.
EVEN THOUGH CAPES TOMORROW AFTERNOON FORECAST TO BE IN 1000-1500
J/KG RANGE WILL STILL HAVE STRONG RIDGE OVER THE AREA.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS MONDAY
EVENING THROUGH WEDNESDAY.
&&
.MARINE...
EAST TO NORTHEAST WINDS CONTINUE OVER THE LAKE THIS AFTERNOON. A
FEW LOCATIONS REPORTING WIND SPEEDS IN THE 15 TO 20 KNOT RANGE.
THESE CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE EARLY EVENING
HOURS. THE 12Z BUFKIT RUN SHOWS A POCKET OF 20 TO 30 KNOT WINDS
WITHIN 1KFT OF THE SURFACE OVER THE WESTERN BASIN THROUGH 00Z. WITH
THE EAST TO NORTHEAST FETCH WAVE HEIGHTS COULD REACH 3 TO 5 FEET
OVER THE WEST. EVEN THOUGH THE CONDITIONS ARE MARGINAL...I WILL
CONTINUE THE SMALL CRAFT ADVISORY THROUGH THE EVENING. WINDS WILL
DECREASE OVERNIGHT TO 10 TO 15 KNOTS. A SIMILAR PATTERN WILL SETUP
ON SUNDAY BUT THE PRESSURE GRADIENT SHOULD BE WEAKER AND THEREFORE
THE WINDS NOT AS STRONG. I DO NOT ANTICIPATE SMALL CRAFT CRITERIA
FOR SUNDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LEZ142>145.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC/TK
SHORT TERM...KEC
LONG TERM...GARNET
AVIATION...DJB
MARINE...GARNET
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
809 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 809 PM CDT SAT MAY 18 2013
WITH DEVELOPMENT OF CONVECTION ACROSS WESTERN NEBRASKA IN LAST 3
HOURS...HAVE BEEN ABLE TO SHARPEN SOME OF THE DETAILS IN THE
FORECAST OVER THE NEXT 18 TO 24H.
LARGE AREA OF SEVERE CONVECTION HAS DEVELOPED AROUND NORTH PLATTE
NEBRASKA...WITH ISOLATED NON SEVERE STORM TO TEH NORTHEAST. SOME
OF THESE NONE SEVERE STORMS MAY MOVE INTO SOUTH CENTRAL SD BY 9
PM...WITH MLCAPES FROM 1500 TO 2000 J/KG...CANNOT RULE OUT SOME
LARGE HAIL BUT EFFECTIVE SHEAR REMAINS MARGINAL FOR SUPERCELL
DEVELOPMENT SO ANY HAIL LIKELY TO BE LESS THAN GOLF BALL SIZE. AS
CONVECTIVE LINE MOVES IN...THERE IS A FAVORABLE ALIGNMENT OF THE
0 TO 3 KM SHEAR VECTOR AND EXPECTED LINE ORIENTATION AS IT REACHES
SOUTH CENTRAL SD. IN ADDITION...SBCAPES FROM RAP SOUNDSINGS ARE
STILL EXPECTED TO BE 1500 TO 2000 J/KG. EXPECT THAT THE QLCS WILL
BE ABLE TO USE THIS ENERGY TO MAINTAIN STRUCTURE AND WITH
FAVORABLE SHEAR THERE IS THE POTENTAIL FOR DAMAGING
WINDS...ESPECIALLY WEST OF I29 AND SOUTH OF I90 IN SE SD AND NE
NEBRASKA. A FEW OF THE STRONGER UPDRAFTS MAY ALSO CONTAIN 1 TO 1.5
INCH HAIL. AS THE NIGHT PROGRESSES THE DYNAMICS WILL BECOME A
LITTLE LESS FAVORABLE AND THERE WILL BE MORE CIN TO OVERCOME. AS A
RESULT...MOST OF THE CONVECTIVE ALLOWING MODELS...INCLUDING
HRRR...SHOW THAT THIS WILL MEAN A GRADUAL WEAKENING OF CONVECTION
WITH SEVERE RISK LIKELY DECREASING FAIRLY RAPIDLY BY 09Z OR SO.
HOWEVER,,,STILL ENOUGH ENERGY FOR THUNDERSTORMS TO CONTINUE AND AN
ISOLATED SEVERE WIND OR HAIL REPORT IS NOT OUT OF THE QUESTION AS
STORMS MOVE NORTH OF I90 AN EAST OF I29.
ONE OTHER THING LOOKS MORE CERTAIN IS THAT CONVECTION WILL MOVE
NORTHEAST A LITTLE FASTER THAN EARLIER EXPECTED AND MAY BE
NORTHEAST OF MARSHALL AND WINDOM BY 7 OR 8 AM ON SUNDAY. THIS MAY
ALLOW FOR SOME RECOVERY OF THE AIR MASS...ESPECIALLY IN NW IA AND
FAR SOUTHEAST SOUTH DAKOTA SUNDAY MORNING INTO EARLY AFTERNOON.
THEN A MUCH STRONGER WAVE WILL MOVE NORTH. HIGH RES NCAR ENSEMBLE
HAVE ALL MEMBERS SHOWING CONVECTION DEVELOPING IN EASTERN NEBRASKA
IN THE EARLY AFTERNOON AND MOVING NORTHEAST INTO NW IA DURING THE
AFTERNOON. RAP MODEL SOUNDINGS THAT HAVE NOT CONVECTED SHOW
MLCAPES EXCEEDING 3000 J/KG. WHILE THE 0 TO 6 KM SHEAR IS
MARGINAL...25 TO 30 KTS...THE 0 TO 1 KM SHEAR IS 15 TO 20 KTS. SO
WHILE NOT THE BEST SUPERCELL SET UP CANNOT COMPLETELY DISMISS THE
TORNADO THREAT TOMORROW IN NORTHWEST IOWA. BUT CERTAINLY LOOKS
LIKE ANOTHER THREAT FOR DAMAGING WINDS AND HAIL UP TO GOLF BALL
SIZE. SO HAVE INCREASED POPS IN NW IA AND SW MN TOMORROW
AFTERNOON.
UPDATED ZFP AND GRIDS OUT. WILL BE UPDATING HWO WITH LATEST
THINKING FOR BOTH TONIGHT AND SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 320 PM CDT SAT MAY 18 2013
AT THIS TIME...SURFACE TROUGH EXTENDS FROM NORTH CENTRAL SD TO WEST
CENTRAL NE. ALOFT...LARGE TROUGH EXISTS THROUGHOUT THE INTERMOUNTAIN
WEST WITH WATER VAPOR SHOWING A SHORT WAVE NEAR THE FOUR CORNERS
AREA. THE SHORT WAVE WILL LIFT EASTWARD TONIGHT INTO THE
SOUTHWESTERN PLAINS AREA. AT THE SURFACE...THERE ARE SOME
INDICATIONS THAT A SURFACE LOW WILL GENERATE IN SOUTH CENTRAL SOUTH
DAKOTA AS THE NIGHT PROGRESSES. THE LOW LEVEL JET INCREASES MODESTLY
MOSTLY INTO THE 25 TO 30 KNOT RANGE AT 850MB. PERSISTENT LOW LEVEL
THETAE ADVECTION EXISTS. BECAUSE OF ITS PERSISTENCE...IT IS
DIFFICULT TO ASCERTAIN GOOD DETAILS ON EXACTLY WHAT THE CONVECTION
MAY DO AFTER IT FIRES UP THIS EVENING. IN THE NEAR TERM...WOULD NOT
BE SURPRISED TO SEE SOME SCATTERED SHOWERS AND AN ISOLATED
THUNDERSTORM IN OUR SOUTHEASTERN ZONES LATE THIS AFTERNOON AND EARLY
EVENING WHERE CUMULUS HAS DEVELOPED. BUT OVERALL...TRYING TO FIGURE
OUT WHEN THE MORE BONAFIDE CONVECTION WILL DEVELOP AND WHEN IS A
LITTLE MORE CHALLENGING. PER UPPER QG FORCING...THE UPPER WAVE
ACTUALLY STAYS TO THE WEST OF OUR AREA. SO EXAMINING DETAILS LOWER...
700-500MB QG DOES SHOW A SHORT WAVE MOVING ACROSS OUR FORECAST AREA
TONIGHT EXITING TO THE EAST ON SUNDAY MORNING. CONVECTION SHOULD
FIRST FIRE NEAR THE SURFACE TROUGH CLOSE TO THE SHORT WAVE EARLY
THIS EVENING...POSSIBLY IMPACTING SOME OF OUR WESTERN ZONES EARLY
THIS EVENING. IT SHOULD THEN MOVE EAST TO NORTHEAST ALONG THE MID
LEVEL FLOW. A SEVERE POTENTIAL CERTAINLY EXISTS. BUT SEEING THE
AMOUNT OF CLOUD COVER WHICH HELD ON TODAY...ML CAPES ARE LIKELY
OVERDONE A BIT OFF OF THE NAM MODEL. IN ADDITION...NAM SURFACE DEW
POINTS ARE A LITTLE HIGH. WIND WISE...DECENT SHEAR EXISTS IN OUR
WESTERN ZONES THIS EVENING BEFORE WANING IN THAT AREA...WITH THE
SHEAR SHIFTING EASTWARD TOWARD THE I 29 CORRIDOR OVERNIGHT AND LATE
TONIGHT. HAVE SEEN BETTER SHEAR FOR THIS TIME OF YEAR...BUT STRONG
WIND IS CERTAINLY A THREAT WITH ANY QLCS DEVELOPMENT ALONG WITH
BOWING SEGMENTS...AND THE SHEAR IS PERPENDICULAR TO ANTICIPATED
CONVECTIVE MOVEMENT. LARGE HAIL COULD ALSO BE A THREAT IN OUR
WESTERN ZONES THIS EVENING WITH ANY DISCREET CELL DEVELOPMENT. HIGH
POPS ARE CERTAINLY WARRANTED...ESPECIALLY ALONG AND NORTH OF I 90
WITH LESS...SCATTERED TYPE POPS FROM SIOUX CITY IA TO STORM LAKE IA.
BUT THEY COULD SEE SOME DECENT RAIN ALSO...JUST LIKELY NOT AS
WIDESPREAD.
ON SUNDAY...SURFACE WIND FIELDS SHOW THE LIKELIHOOD OF A TROUGH
THROUGH OUR SOUTHWEST ZONES BY AFTERNOON. ACTUALLY PREFER THE
ORIENTATION OF THE GFS AND ECMWF WITH THE PRECIPITATION FIELDS BY
SUNDAY AFTERNOON...WITH A DEVELOPING LINE JUST AHEAD OF THE WIND
SHIFT NEAR THE I 29 CORRIDOR. DEPENDING ON CLOUD COVER DEBRIS...
THIS ACTIVITY COULD ALSO BE SEVERE. FOR MUCH OF THE DAY...AM A BIT
CONCERNED THAT SOME OF OUR POPS COULD BE OVERDONE...ESPECIALLY IN
OUR WESTERN ZONES. BUT WARM AIR ADVECTION DOES PERSIST ALOFT THROUGH
THE DAY.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 320 PM CDT SAT MAY 18 2013
ANY CONVECTION THAT DEVELOPS THROUGH THE CENTRAL PORTIONS OF THE CWA
WILL PUSH OFF TO THE EAST THROUGH THE EVENING...WITH SOME SEVERE
STORMS STILL POSSIBLE DURING THE EVENING BEFORE THE INSTABILITY
WANES LATER IN THE EVENING. THINK THERE WILL BE A GENERAL DECREASE
IN COVERAGE OF CONVECTION LATER AT NIGHT WITH DRYING MIDLEVELS. DO
BEGIN TO SEE THERMAL PROFILES COOL JUST A BIT...WITH LOWS RANGING
FROM THE LOWER 60S EAST TO MID 50S WEST.
MESSY PATTERN CONTINUES THROUGH AT LEAST MIDWEEK AS AN UPPER LEVEL
LOW SPINS OVER THE THE CENTRAL PORTIONS OF THE NATION FOR MONDAY
AND TUESDAY BEFORE PUSHING INTO THE NORTHERN MISSISSIPPI
VALLEY/WESTERN GREAT LAKES REGION ON WEDNESDAY. WITH THIS
FEATURE...WILL HAVE PERIODIC SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE AREA DURING THIS TIME FRAME. OF COURSE HARD TO
PINPOINT CONVECTIVE TIMING/DEVELOPMENT IN THIS KIND OF SET
UP...WITH VARIOUS SHORTWAVES/VORT MAXES ROTATING AROUND THE UPPER
LEVEL LOW THROUGH THE PERIOD. HOWEVER...AT THIS POINT THE BETTER
CHANCE OF PRECIPITATION ON MONDAY LOOKS TO BE OVER THE WEST CLOSER
TO THE PARENT LOW/WIND SHIFT LINE...THEN SHIFTING EASTWARD ON
TUESDAY AND WEDNESDAY AS THE DYNAMICS/BEST LIFT PULLS OFF TO THE
EAST. WOULD NOT REALLY EXPECT MUCH IN THE WAY OF SEVERE STORMS
THROUGH THIS PERIOD WITH AN INCREASINGLY STABLE
ATMOSPHERE...THOUGH AS MENTIONED IN PREVIOUS DISCUSSION CANNOT
RULE BRIEF FUNNEL CLOUDS/SPIN UPS ON MONDAY OR TUESDAY AFTERNOON
WITH THE COLD CORE LOW OVERHEAD...BUT WOULD DEPEND ON
PRECIPITATION TRENDS/BREAKS IN CLOUDS/AND RESULTANT LOW LEVEL
LAPSE RATES ETC. WITH THE LOW OVERHEAD...WILL SEE A GENERAL
COOLING TREND THROUGH MID WEEK...WITH HIGHS TRENDING TOWARD BELOW
NORMAL LEVELS...INTO THE 50S AND 60S FOR TUESDAY AND WEDNESDAY.
FARTHER OUT IN THE EXTENDED...THE UPPER LEVEL LOW CONTINUES TO FILL
AND PULL OFF TO THE EAST FOR THE END OF THE WEEK...WITH UPPER
LEVEL RIDGING INTO THE PLANS STATES FOR THURSDAY THROUGH SATURDAY.
WITH THIS COMES A WARMING TREND...BACK TO NORMAL...AND MOSTLY DRY
CONDITIONS THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 735 PM CDT SAT MAY 18 2013
CONCERN OVER THE THIS TAF PERIOD WILL 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 IS
EXPECTED TO CONTINUE TO EXPAND AND MOVE NORTHEAST INTO OUR AREA.
BASED ON LATEST HIGH RESOLUTION MODELS...WENT AHEAD AND SPED UP
TIMING OF CONVECTION...WITH IT ENTERING GREGORY COUNTY AROUND 03Z-
04Z...AND THE THREE TAF SITES BETWEEN 04Z AND 06Z. 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.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...SCHUMACHER
SHORT TERM...MJF
LONG TERM...JM
AVIATION...CHENARD
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
401 PM CDT FRI MAY 17 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
THE MODELS ALL AGREE WELL AND CONTINUE TO BE VERY CONSISTENT AT
BRINGING THE UPPER LEVEL LOW PRESSURE TROUGH OUT OF THE SOUTHWEST
US THROUGH SUNDAY NIGHT AND CLOSING IT OFF. THUNDERSTORMS ARE
BEGINNING TO DEVELOP IN WESTERN SOUTH DAKOTA LATE THIS AFTERNOON
AND WILL CONTINUE TO DEVELOP AND MOVE EAST INTO CENTRAL AND NORTH
CENTRAL SOUTH DAKOTA THROUGH THE EVENING. THE HRRR MODEL SHOWS
THIS DEVELOPMENT VERY WELL. AS THE LLJ INCREASES INTO THE EVENING
HOURS...EXPECT THIS TREND TO CONTINUE. WITH INSTABILITY INCREASING
ALONG WITH DEEP LAYER SHEAR...SOME SEVERE STORMS ARE POSSIBLE
MAINLY WEST OF THE JAMES VALLEY TONIGHT. THIS FIRST WAVE WILL MOVE
THROUGH WITH MORE DEVELOPMENT EXPECTED SATURDAY AFTERNOON AND
EVENING ACROSS THE CWA. HIGH INSTABILITY WILL BUILD UP AGAIN
SATURDAY AFTERNOON AND EVENING ACROSS THE CWA WHILE ANOTHER SHORT
WAVE TROUGH KICKS OUT OF THE SOUTHWEST UPPER TROUGH. THIS
INTERACTION ALONG A GOOD LOW LEVEL SURFACE BOUNDARY/WARM FRONT ON
SATURDAY AFTERNOON AND EVENING WILL RESULT IN NUMEROUS SHOWERS AND
THUNDERSTORMS AGAIN. SEVERE STORMS LOOK LIKE A GOOD POSSIBILITY
ON SATURDAY AFTERNOON AND EVENING. AS THE MAIN UPPER LEVEL TROUGH
LIFTS INTO THE REGION SUNDAY AND SUNDAY NIGHT AND CLOSES
OFF...SHOWER AND THUNDERSTORM POSSIBILITIES WILL CONTINUE TO BE
VERY GOOD ACROSS ALL OF THE CWA. HEAVY RAIN WILL ALSO BE A THREAT
ACROSS THE CWA AS HIGH PRECIPITABLE WATERS WILL BE AVAILABLE FOR
STORMS.
.LONG TERM...MONDAY THROUGH FRIDAY
DECENT AGREEMENT EXISTS BETWEEN DETERMINISTIC GUIDANCE TO START
THINGS OFF WITH A NEARLY STATIONARY UPPER LOW OVER THE EASTERN
DAKOTAS/MINNESOTA. THIS FEATURE WILL DRIFT SLOWLY TO THE
EAST...WITH WRAP AROUND MOISTURE AND WEAK INSTABILITY LEADING TO
CONSTANT WIDESPREAD SHOWER ACTIVITY...WHICH WILL ALSO RESULT IN
TEMPERATURES BELOW NORMAL FOR MUCH OF THE EXTENDED. ONCE THE UPPER
LOW PUSHES EAST...A COL AREA FORMS OVERHEAD...WITH WEAK
SOUTHEASTERLY LOW LEVEL RETURN FLOW DEVELOPING FOR THE END OF THE
PERIOD...WITH MILDER TEMPERATURES AND LIKELY DRY CONDITIONS.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS FOR KABR/KMBG...WITH KATY/KPIR MIXING OUT MVFR
CIGS BY THE EARLY AFTERNOON. A FEW WEAK SHOWERS COULD
DEVELOPS AT KABR/KATY THIS AFTERNOON WITH NEGLIGIBLE EFFECT. MAIN
THREAT WILL BE STORMS PUSHING INTO THE KPIR/KMBG TERMINALS DURING
THE EVENING. THIS AREA OF CONVECTION WILL THEN POSSIBLY IMPACT
KABR/KATY TERMINALS OVERNIGHT. THERE IS THE POSSIBILITY THAT
CONVECTION WILL LEAVE US WITH MVFR CIGS BY THE MORNING...THOUGH
WITH LOW FORECASTER CONFIDENCE. WINDS WILL BE OUT OF THE
EAST/SOUTHEAST...BUT WILL INCREASE IN INTENSITY SOMEWHAT AS THEY
SHIFT TO DUE SOUTH EARLY SATURDAY.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...MOHR
LONG TERM...CONNELLY
AVIATION...CONNELLY
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1157 PM CDT THU MAY 16 2013
.UPDATE...FOR 06Z AVIATION DISCUSSION.
&&
.AVIATION...06Z AVIATION DISCUSSION.
UNCERTAINTIES...ACTUAL SHWRS/TSTMS LOCATION DEVELOPMENT...TRANSITIONAL TIMING
FROM VFR/MVFR CEILINGS AND ACTUAL COVERAGE OF SHWRS/TSTMS 17/10Z-18/06Z. STILL
EXPECTING OVERALL INCREASING INSTABILITY...MOISTURE...AND LIFTING MECHANISM THRU
18/06Z...ESPECIALLY AFTER 17/10Z...AND WILL CONTINUE WITH A GENERAL TREND OF
VCSH THRU 17/11Z...TRANSITIONING TO CAT SHWRS/TSTMS 17/11Z-18/06Z...AS OPENING
UPPER LEVEL LOW/UPPER LEVEL TROUGH MOVES ACROSS WRN COUNTIES AND THEN ACROSS
REST OF MID STATE. STILL BELIEVE THAT ACTIVITY MAY BE MORE DIURNAL BASED ERN
PORTIONS OF MID STATE AS OF 17/12Z-18/00Z AND THUS WILL CONTINUE WITH VCTS
REMARKS AS LOCATION DEVELOPMENT UNCERTAIN THRU AT LEAST 18/00Z. CAT SHWRS/TSTMS
ALL AREAS EXPECTED BETWEEN 18/00Z-18/06Z.
&&
.PREV DISCUSSION.../ISSUED 658 PM CDT THU MAY 16 2013/
UPDATE...
JUST ISOLATED SHOWER AND TSTM ACTIVITY THUS FAR ACROSS THE MID
STATE THIS EVENING. BETTER COVERAGE OF SHOWERS AND TSTMS EXISTS
BACK TO OUR WEST ACROSS AR. MODELS ARE IN AGREEMENT WITH THIS
DEEPER AREA OF MOISTURE SPREADING EASTWARD AND REACHING WESTERN
PORTIONS OF MIDDLE TN TOWARD SUNRISE. HRRR FURTHER SUPPORTS AN
INCREASE IN OUR POPS OVERNIGHT FOR MAINLY OUR WESTERN AREAS.
THUS...WILL GO AHEAD AND MODIFY THE WEATHER GRIDS AND SEPARATE THE
OVERNIGHT GRIDS INTO TWO...00Z-06Z AND 06Z-12Z. WILL EXPAND THE LIKELY
POPS OVER OUR WEST AND MOVE THE CHC CATEGORY A LITTLE FURTHER EAST
AS WELL.
REMAINDER OF FCST IS IN GOOD SHAPE. SEE NO REASON FOR ANY FURTHER
MODS. UPDATES OUT SHORTLY.
PREV DISCUSSION.../ISSUED 312 PM CDT THU MAY 16 2013/
SHORT TERM...RIDGE OF HIGH PRESSURE SITUATED EAST OF MIDDLE
TENNESSEE THIS AFTERNOON, ALLOWING ADVECTION OF WARM, MOIST AIR TO
TAKE PLACE. LATEST LAPS SOUNDING SHOWS INSTABILITY GRADUALLY
INCREASING WITH AFTERNOON HEATING, BUT ATMOSPHERE BELOW 600 MB IS
STILL LARGELY DRY. LOOK FOR SATURATION TO GRADUALLY TAKE PLACE
LATER TONIGHT AS TOMORROW S A SHORTWAVE APPROACHES MIDDLE
TENNESSEE FROM THE WEST AND BEGINS TO SPREAD CONVECTION ACROSS THE
MID STATE. LOOK FOR MAINLY SCATTERED ACTIVITY WEST OF THE PLATEAU
OVERNIGHT, WITH POP`S INCREASING TOMORROW.
CENTER OF UPPER LOW MOVES INTO SOUTHWESTERN KENTUCKY BY TOMORROW
AFTERNOON ACCOMPANIED BY A GOOD BAND OF LIFT OVER OUR WESTERN
COUNTIES. THUS, HAVE GONE WITH CATEGORICAL POPS FOR THOSE AREAS
TOMORROW, RANGING TO 50% POPS ALONG THE UPPER CUMBERLAND.
SHORTWAVE CONTINUES SLOWLY EASTWARD FRIDAY NIGHT, WITH SHOWERS
AND THUNDERSTORMS LIKELY AREA-WIDE. ATMOSPHERIC MOISTURE REMAINS
DEEP ON SATURDAY, ESPECIALLY NORTH AND EAST, WHERE SHOWERS AND
THUNDERSTORMS WILL REMAIN LIKELY.
WESTERN AREAS SHOULD START TO DRY OUT BY LATE SATURDAY NIGHT, AS
UPPER LOW CENTER MOVES TO NEAR SOUTHWEST VIRGINIA BY 12Z SUNDAY.
RIDGE OF HIGH PRESSURE BUILDS IN OVER THE AREA EARLY NEXT WEEK,
ALLOWING FOR MORE DAYTIME SUNSHINE AND SENDING DAYTIME HIGHS
PUSHING INTO THE MIDDLE AND UPPER 80S BOTH MONDAY AND TUESDAY.
LONG TERM...DURING THE MIDDLE TO LATTER PART OF NEXT WEEK, EXPECT
UPPER RIDGE TO PUSH EAST, ALLOWING FOR A MOIST SOUTHWEST FLOW TO
DEVELOP FROM THE SOUTHERN PLAINS AND LOWER MISSISSIPPI RIVER VALLEY
UP ACROSS THE TENNESSEE AND OHIO RIVER VALLEYS. SHOWERS AND
THUNDERSTORMS WILL PROBABLY BECOME LIKELY AGAIN BY WEDNESDAY, WITH
AT LEAST SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS LINGERING
INTO THURSDAY AS WELL.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1016 PM CDT SAT MAY 18 2013
.UPDATE...
EVENING UPDATE WILL REMOVE MENTION OF ISOLATED THUNDERSTORMS FOR
THE REMAINDER OF THE NIGHT. ENVIRONMENT ACROSS NORTH TEXAS HAS
CONSIDERABLE CONDITIONAL INSTABILITY HOWEVER IT WILL REMAIN CAPPED
TO DEEP CONVECTION. WHAT APPEARED TO BE MORE FAVORABLE EARLIER WAS
THE THREAT FOR DOWNBURST WINDS OR HEATBURSTS FROM CONVECTION TO
THE WEST. WITH ABUNDANT DRY AIR IN THE MID LEVELS AND AMPLE ANVIL
DEBRIS SPREADING EASTWARD...A FAVORABLE SETUP FOR THE PHENOMENON
WAS IN PLACE. LACK OF SUBSTANTIAL DEEP CONVECTION TO THE WEST OF
OUR AREA HOWEVER HAS FOR ALL INTENTS AND PURPOSES SQUASHED THIS
SCENARIO. WARM AND BREEZY CONDITIONS EXPECTED OVERNIGHT WITH MOST
THUNDERSTORM ACTIVITY REMAINING WELL TO THE NORTH OF OUR AREA.
ONLY CHANGE TO CURRENT FORECAST WAS TO REMOVE MENTION OF
THUNDERSTORMS.
DUNN
&&
.AVIATION...
FOR THE 00Z TAFS...TIMING THE ONSET OF STRATUS...AND THE IMPACT OF
ANY ANVIL CLOUD PRECIPITATION OVER METROPLEX AREA TAF SITES ARE
THE PRIMARY FORECAST CONCERNS.
REGARDING STRATUS...KEPT MVFR STRATUS IN THE FORECAST FOR A FEW
HOURS TOMORROW MORNING AS MOST GUIDANCE AGREES THAT A 50 KT LOW
LEVEL JET WILL RAMP UP OVER NORTH TX TONIGHT. THIS STRONG JET WILL
HELP KEEP GULF MOISTURE IN PLACE...BUT THERE IS UNCERTAINTY
REGARDING THE PRESENCE OF STRATUS WITHIN THE LOW LEVEL JET. THE
LOW LEVEL JET IS NOT EXPECTED TO BE ASSOCIATED WITH STRONG WARM
AIR ADVECTION OVERNIGHT...THEREFORE THERE WILL ONLY BE SHALLOW
LIFT WITHIN THE CORE OF THE JET OVER NORTH TX. THIS SHALLOW LIFT
MAY BE SUFFICIENT FOR STRATUS TO FORM...BUT THERE IS NO GUARANTEE
THAT THIS WILL PAN OUT. THE LAMP IS AGGRESSIVE WITH THE STRATUS AS
IT HAS BEEN RECENTLY. THE RAP FORECAST SOUNDINGS DO NOT SUPPORT
THE DEVELOPMENT OF STRATUS WHILE THE NAM DOES. AT THIS POINT JUST
KEPT THE STRATUS IN THE FORECAST BUT BUMPED UP THE CIGS TO 2500 FT
WHICH SHOULD HAVE LITTLE IMPACT ON AIRPORT OPERATIONS EVEN IF IT
IS IN PLACE.
REGARDING ANVIL CLOUD PRECIPITATION TONIGHT...PLACED A MENTION OF
LIGHT RAIN WITH GUSTY WINDS IN THE FORECAST FROM 06 TO 09Z FOR
METROPLEX AREA TAF SITES. THIS WILL ONLY OCCUR IF STORMS BECOME
ESTABLISHED AROUND ABILENE THIS EVENING. AT THE TIME OF THIS
DISCUSSION VISIBLE SATELLITE AND REGIONAL RADAR SHOWED SOME GOOD
CONVECTIVE ATTEMPTS JUST NORTH OF ABILENE...AND THIS TIPPED THE
SCALE TOWARDS INCLUDING THE LIGHT ANVIL PRECIPITATION IN METROPLEX
AREA TAFS. ANY LIGHT RAIN IN THE EXTREMELY UNSTABLE AIR MASS IN
PLACE OVER NORTH TX WILL RESULT IN HEAT BURSTS...OR HEAT BURST LIKE
ACTIVITY. ESSENTIALLY VERY GUSTY WINDS ACCOMPANIED BY A WARMING
AND DRYING OUT OF THE NEAR SURFACE AIR. IF THE ABILENE ACTIVITY
NEVER BECOMES ESTABLISHED...WILL REMOVE THIS GROUP FROM THE TAFS
IN FUTURE AMENDMENTS.
CAVANAUGH
&&
.PREV DISCUSSION... /ISSUED 324 PM CDT SAT MAY 18 2013/
A SLOW MOVING UPPER LEVEL TROUGH OVER THE PLAINS WILL PUT THE
REGION IN AN ACTIVE WEATHER PATTERN THROUGH TUESDAY WITH SEVERE
WEATHER POSSIBLE EACH DAY. PRIMARILY THE NORTHWEST/NORTHERN PARTS
OF THE CWA WILL BE IMPACTED BY CONVECTION TONIGHT THROUGH
MONDAY...BUT THE CENTRAL AND SOUTHERN CWA WILL BE UNDER THE GUN
FOR A WIDESPREAD RAIN EVENT TUESDAY AFTERNOON AND EVENING. THE
MAIN CHANGE WITH THIS FORECAST CONCERNS TONIGHT...AND THE ADDITION
OF POPS FOR AREAS NORTH OF I-20...NOT NECESSARILY FOR SUPERCELL
TYPE CONVECTION...BUT FOR VERY HIGH BASED WEAK CONVECTION THAT
COULD CAUSE STRONG GUSTY WINDS VIA HEATBURSTS LATE THIS EVENING.
THIS AFTERNOON THE DRY LINE REMAINS WELL TO THE WEST OF THE REGION
AND SHORT-TERM GUIDANCE SUGGESTS IT WILL STAY AS FAR WEST AS A
CHILDRESS TO SAN ANGELO LINE. THIS RESULTS IN SOME CONCERNS ABOUT
WHETHER SURFACE BASED CONVECTION WILL INITIATE CLOSE ENOUGH TO
ENTER THE CWA. MID LEVEL WESTERLY FLOW IS STRONGER TODAY...AND
THEREFORE STORM MOTIONS WOULD BE MORE EASTERLY. SURFACE BASED
CONVECTION WOULD HAVE ENOUGH SHEAR AND INSTABILITY TO BECOME
SUPERCELLS AND PRODUCE SIGNIFICANT SEVERE WEATHER. LOCAL OBJECTIVE
ANALYSIS INDICATES THE BEST AXIS OF INSTABILITY AND DIMINISHED CIN
IS TO THE WEST OF THE CWA...WITH THE AIRMASS OVER OUR WESTERN
COUNTIES NOT QUITE AS UNSTABLE WITH CAPE AT 1500-2500 J/KG AND
HIGHER CIN DUE TO DEWPOINTS DROPPING INTO THE LOW 60S. WATER VAPOR
LOOP AND MODEL GUIDANCE DOES INDICATE A SHORTWAVE IS APPROACHING
FROM THE SOUTHWEST AND THE LIFT PROVIDED BY THIS FEATURE SHOULD
ALLOW SURFACE BASED CONVECTION TO INITIATE AND ORGANIZE WEST OF
THE CWA. SOME OF THIS ACTIVITY SHOULD ENTER THE NW ZONES...BUT
BELIEVE THE CELLS MAY WEAKEN A BIT AND BECOME ELEVATED DUE TO THE
SLIGHTLY LESS FAVORABLE ENVIRONMENT. IN SUMMARY...A SEVERE THREAT
EXIST FOR PRIMARILY HAIL/WIND...AND POPS ARE NEAR 20-30 PERCENT IN
THE NW ZONES EARLY THIS EVENING. THE RISK FOR GIANT HAIL OR
TORNADOES DOES NOT LOOK AS HIGH AS IT DID YESTERDAY IN OUR CWA.
CURRENTLY...WEAK ELEVATED CONVECTION BASED AT AROUND 14000FT
CONTINUES TO BUBBLE UP OVER THE WESTERN ZONES. MOST OF THE PRECIP
IS EVAPORATING BEFORE REACHING THE GROUND...BUT THIS ELEVATED
MOISTURE PLUME LOOKS LIKE IT WILL HAVE IMPLICATIONS ON THE FORECAST
OVER THE NORTHERN HALF OF THE AREA TONIGHT. ESSENTIALLY THERE ARE
A FEW MODELS NOW INDICATING A MOISTURE PLUME FROM 500-600MB
ENTERING THE NORTHERN HALF OF THE AREA...LIKELY ASSOCIATED WITH
ANVILS FROM STORMS TO THE WEST. THE ISSUE IS THAT THIS MOISTURE
WILL BE WITHIN AN AREA OF DRY ADIABATIC LAPSE RATES...AND
COINCIDES WITH UPPER LEVEL FORCING FROM THE SHORTWAVE. THE STAGE
IS SET FOR SCATTERED ELEVATED CONVECTION WITH BASES ABOVE 12000FT.
MOST OF THE RAIN WILL EVAPORATE DUE TO VERY DRY AIR BELOW 600MB...
BUT SPORADIC LIGHTNING STRIKES WILL BE POSSIBLE TONIGHT.
MEANWHILE...A 50KT SOUTHERLY LOW LEVEL JET WILL BE DEVELOPING AND
THE ENVIRONMENT WILL BE FAVORABLE FOR THIS HIGH BASED CONVECTION
TO TRANSFER STRONG WINDS TO THE SURFACE IN WHAT IS TECHNICALLY A
TYPE OF HEATBURST. THIS IS TOUGH TO COMMUNICATE TO THE PUBLIC IN
SIMPLE TERMS...BUT THE POPS ARE FOR MEASURABLE RAIN AND THE CHANCE
FOR THAT IS LOW. HOWEVER GUSTY WINDS AND LIGHT RAIN MAY AFFECT A
LARGE PORTION OF THE NORTHERN CWA TONIGHT...AND THEREFORE HAVE
BUMPED UP SOUTH WINDS TO 20-25 MPH AND MENTIONED GUSTS TO 40 MPH
IN THE ZONES. THIS FORECAST IS NOT OF HIGH CONFIDENCE...PARTLY
BECAUSE IT MAY BE THE FIRST NWS FORECAST THAT HAS EVER TRIED TO
INCLUDE A RISK OF HEATBURSTS IN A ZONE FORECAST. HOWEVER LOOKING
AT ALL OF THE DATA...THE SETUP TONIGHT LOOKS VERY FAVORABLE FOR
PERIOD OF GUSTY SOUTH WINDS BENEATH ELEVATED RADAR ECHOES. WE
SHALL SEE.
A STRONG SHORTWAVE TROUGH WILL ROTATE THROUGH THE SOUTHERN PLAINS
TOMORROW AND WILL PUSH THE DRYLINE FARTHER TO THE EAST INTO THE NW
ZONES. WITH DAYTIME HEATING...CIN SHOULD BE LOW ENOUGH OVER THE NW
ZONES FOR ISOLATED SEVERE STORMS TO DEVELOP IN THE AFTERNOON.
WIND FIELDS WILL STRENGTHEN A BIT AND SUPERCELL STORM MOTION WILL
BE EASTERLY. WEST TO EAST STORM TRACKS ON SUNDAY EVENING MEANS
POPS WILL COVER THE AREAS NORTH OF I-20. LOW LEVEL HELICITY RAMPS
UP AROUND SUNSET SUNDAY EVENING AND IF SUPERCELLS CAN OVERCOME THE
WEAK CIN AND TAP INTO SURFACE PARCELS...A TORNADO THREAT WILL
EXIST. MONDAY LOOKS LIKE A CARBON COPY OF SUNDAY/S PATTERN WITH
THE MAIN FEATURES IN THE SAME PLACE...JUST A LITTLE WEAKER CIN SO
POPS ARE SLIGHTLY HIGHER/FARTHER SOUTH. TEMPS WILL REMAIN NEAR
PERSISTENCE AND WINDS WILL BE BREEZY SUNDAY AND MONDAY.
ON TUESDAY THE UPPER TROUGH WILL BEGIN TO FINALLY MOVE EAST AND
THIS WILL PUSH A COLD FRONT INTO THE NW ZONES TUESDAY AFTERNOON.
SCATTERED TO NUMEROUS STORMS SHOULD FIRE ALONG THE COLD FRONT
TUESDAY AFTERNOON AND WORK EAST AND SOUTHEAST ACROSS MUCH OF THE
AREA INTO TUESDAY NIGHT. RAINFALL MAY BE WIDESPREAD AND AVERAGE
1/2 TO 1 INCH. SEVERE WEATHER WILL BE A CONCERN GIVEN HIGH
INSTABILITY AND ADEQUATE DEEP LAYER SHEAR.
THE FRONT WILL PUSH THROUGH THE REGION AND DRIER AIR WILL END RAIN
CHANCES FROM NORTH TO SOUTH WEDNESDAY. LOW TEMPS WILL COOL A BIT
AND INTO THE 60S DUE TO THE LOWER DEWPOINTS...BUT HIGHS WILL
CONTINUE IN THE MID 80S TO NEAR 90 THROUGH THE REMAINDER OF THE
WEEK. WILL KEEP THE FORECAST DRY AS AN UPPER RIDGE SETTLES INTO
THE AREA...BUT WE MAY HAVE TO WATCH FOR NW FLOW MCS ACTIVITY ON
FRIDAY NIGHT IN THE NW ZONES. TOO FAR OUT TO RELY ON THE MODEL
FORECASTS FOR THIS POSSIBILITY AT THIS TIME.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 73 90 72 89 72 / 5 10 20 10 20
WACO, TX 72 90 73 90 73 / 5 5 5 5 10
PARIS, TX 70 88 70 87 70 / 10 10 20 10 40
DENTON, TX 73 90 71 89 70 / 10 10 20 20 30
MCKINNEY, TX 73 89 71 88 71 / 10 10 20 10 30
DALLAS, TX 75 91 74 90 74 / 5 10 20 10 20
TERRELL, TX 72 88 71 89 73 / 5 5 20 10 20
CORSICANA, TX 71 89 72 89 73 / 5 5 5 5 10
TEMPLE, TX 71 89 73 90 73 / 5 5 5 5 10
MINERAL WELLS, TX 71 93 70 92 71 / 5 20 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
705 PM CDT SAT MAY 18 2013
.AVIATION...
FOR THE 00Z TAFS...TIMING THE ONSET OF STRATUS...AND THE IMPACT OF
ANY ANVIL CLOUD PRECIPITATION OVER METROPLEX AREA TAF SITES ARE
THE PRIMARY FORECAST CONCERNS.
REGARDING STRATUS...KEPT MVFR STRATUS IN THE FORECAST FOR A FEW
HOURS TOMORROW MORNING AS MOST GUIDANCE AGREES THAT A 50 KT LOW
LEVEL JET WILL RAMP UP OVER NORTH TX TONIGHT. THIS STRONG JET WILL
HELP KEEP GULF MOISTURE IN PLACE...BUT THERE IS UNCERTAINTY
REGARDING THE PRESENCE OF STRATUS WITHIN THE LOW LEVEL JET. THE
LOW LEVEL JET IS NOT EXPECTED TO BE ASSOCIATED WITH STRONG WARM
AIR ADVECTION OVERNIGHT...THEREFORE THERE WILL ONLY BE SHALLOW
LIFT WITHIN THE CORE OF THE JET OVER NORTH TX. THIS SHALLOW LIFT
MAY BE SUFFICIENT FOR STRATUS TO FORM...BUT THERE IS NO GUARANTEE
THAT THIS WILL PAN OUT. THE LAMP IS AGGRESSIVE WITH THE STRATUS AS
IT HAS BEEN RECENTLY. THE RAP FORECAST SOUNDINGS DO NOT SUPPORT
THE DEVELOPMENT OF STRATUS WHILE THE NAM DOES. AT THIS POINT JUST
KEPT THE STRATUS IN THE FORECAST BUT BUMPED UP THE CIGS TO 2500 FT
WHICH SHOULD HAVE LITTLE IMPACT ON AIRPORT OPERATIONS EVEN IF IT
IS IN PLACE.
REGARDING ANVIL CLOUD PRECIPITATION TONIGHT...PLACED A MENTION OF
LIGHT RAIN WITH GUSTY WINDS IN THE FORECAST FROM 06 TO 09Z FOR
METROPLEX AREA TAF SITES. THIS WILL ONLY OCCUR IF STORMS BECOME
ESTABLISHED AROUND ABILENE THIS EVENING. AT THE TIME OF THIS
DISCUSSION VISIBLE SATELLITE AND REGIONAL RADAR SHOWED SOME GOOD
CONVECTIVE ATTEMPTS JUST NORTH OF ABILENE...AND THIS TIPPED THE
SCALE TOWARDS INCLUDING THE LIGHT ANVIL PRECIPITATION IN METROPLEX
AREA TAFS. ANY LIGHT RAIN IN THE EXTREMELY UNSTABLE AIR MASS IN
PLACE OVER NORTH TX WILL RESULT IN HEAT BURSTS...OR HEAT BURST LIKE
ACTIVITY. ESSENTIALLY VERY GUSTY WINDS ACCOMPANIED BY A WARMING
AND DRYING OUT OF THE NEAR SURFACE AIR. IF THE ABILENE ACTIVITY
NEVER BECOMES ESTABLISHED...WILL REMOVE THIS GROUP FROM THE TAFS
IN FUTURE AMENDMENTS.
CAVANAUGH
&&
.PREV DISCUSSION... /ISSUED 324 PM CDT SAT MAY 18 2013/
A SLOW MOVING UPPER LEVEL TROUGH OVER THE PLAINS WILL PUT THE
REGION IN AN ACTIVE WEATHER PATTERN THROUGH TUESDAY WITH SEVERE
WEATHER POSSIBLE EACH DAY. PRIMARILY THE NORTHWEST/NORTHERN PARTS
OF THE CWA WILL BE IMPACTED BY CONVECTION TONIGHT THROUGH
MONDAY...BUT THE CENTRAL AND SOUTHERN CWA WILL BE UNDER THE GUN
FOR A WIDESPREAD RAIN EVENT TUESDAY AFTERNOON AND EVENING. THE
MAIN CHANGE WITH THIS FORECAST CONCERNS TONIGHT...AND THE ADDITION
OF POPS FOR AREAS NORTH OF I-20...NOT NECESSARILY FOR SUPERCELL
TYPE CONVECTION...BUT FOR VERY HIGH BASED WEAK CONVECTION THAT
COULD CAUSE STRONG GUSTY WINDS VIA HEATBURSTS LATE THIS EVENING.
THIS AFTERNOON THE DRY LINE REMAINS WELL TO THE WEST OF THE REGION
AND SHORT-TERM GUIDANCE SUGGESTS IT WILL STAY AS FAR WEST AS A
CHILDRESS TO SAN ANGELO LINE. THIS RESULTS IN SOME CONCERNS ABOUT
WHETHER SURFACE BASED CONVECTION WILL INITIATE CLOSE ENOUGH TO
ENTER THE CWA. MID LEVEL WESTERLY FLOW IS STRONGER TODAY...AND
THEREFORE STORM MOTIONS WOULD BE MORE EASTERLY. SURFACE BASED
CONVECTION WOULD HAVE ENOUGH SHEAR AND INSTABILITY TO BECOME
SUPERCELLS AND PRODUCE SIGNIFICANT SEVERE WEATHER. LOCAL OBJECTIVE
ANALYSIS INDICATES THE BEST AXIS OF INSTABILITY AND DIMINISHED CIN
IS TO THE WEST OF THE CWA...WITH THE AIRMASS OVER OUR WESTERN
COUNTIES NOT QUITE AS UNSTABLE WITH CAPE AT 1500-2500 J/KG AND
HIGHER CIN DUE TO DEWPOINTS DROPPING INTO THE LOW 60S. WATER VAPOR
LOOP AND MODEL GUIDANCE DOES INDICATE A SHORTWAVE IS APPROACHING
FROM THE SOUTHWEST AND THE LIFT PROVIDED BY THIS FEATURE SHOULD
ALLOW SURFACE BASED CONVECTION TO INITIATE AND ORGANIZE WEST OF
THE CWA. SOME OF THIS ACTIVITY SHOULD ENTER THE NW ZONES...BUT
BELIEVE THE CELLS MAY WEAKEN A BIT AND BECOME ELEVATED DUE TO THE
SLIGHTLY LESS FAVORABLE ENVIRONMENT. IN SUMMARY...A SEVERE THREAT
EXIST FOR PRIMARILY HAIL/WIND...AND POPS ARE NEAR 20-30 PERCENT IN
THE NW ZONES EARLY THIS EVENING. THE RISK FOR GIANT HAIL OR
TORNADOES DOES NOT LOOK AS HIGH AS IT DID YESTERDAY IN OUR CWA.
CURRENTLY...WEAK ELEVATED CONVECTION BASED AT AROUND 14000FT
CONTINUES TO BUBBLE UP OVER THE WESTERN ZONES. MOST OF THE PRECIP
IS EVAPORATING BEFORE REACHING THE GROUND...BUT THIS ELEVATED
MOISTURE PLUME LOOKS LIKE IT WILL HAVE IMPLICATIONS ON THE FORECAST
OVER THE NORTHERN HALF OF THE AREA TONIGHT. ESSENTIALLY THERE ARE
A FEW MODELS NOW INDICATING A MOISTURE PLUME FROM 500-600MB
ENTERING THE NORTHERN HALF OF THE AREA...LIKELY ASSOCIATED WITH
ANVILS FROM STORMS TO THE WEST. THE ISSUE IS THAT THIS MOISTURE
WILL BE WITHIN AN AREA OF DRY ADIABATIC LAPSE RATES...AND
COINCIDES WITH UPPER LEVEL FORCING FROM THE SHORTWAVE. THE STAGE
IS SET FOR SCATTERED ELEVATED CONVECTION WITH BASES ABOVE 12000FT.
MOST OF THE RAIN WILL EVAPORATE DUE TO VERY DRY AIR BELOW 600MB...
BUT SPORADIC LIGHTNING STRIKES WILL BE POSSIBLE TONIGHT.
MEANWHILE...A 50KT SOUTHERLY LOW LEVEL JET WILL BE DEVELOPING AND
THE ENVIRONMENT WILL BE FAVORABLE FOR THIS HIGH BASED CONVECTION
TO TRANSFER STRONG WINDS TO THE SURFACE IN WHAT IS TECHNICALLY A
TYPE OF HEATBURST. THIS IS TOUGH TO COMMUNICATE TO THE PUBLIC IN
SIMPLE TERMS...BUT THE POPS ARE FOR MEASURABLE RAIN AND THE CHANCE
FOR THAT IS LOW. HOWEVER GUSTY WINDS AND LIGHT RAIN MAY AFFECT A
LARGE PORTION OF THE NORTHERN CWA TONIGHT...AND THEREFORE HAVE
BUMPED UP SOUTH WINDS TO 20-25 MPH AND MENTIONED GUSTS TO 40 MPH
IN THE ZONES. THIS FORECAST IS NOT OF HIGH CONFIDENCE...PARTLY
BECAUSE IT MAY BE THE FIRST NWS FORECAST THAT HAS EVER TRIED TO
INCLUDE A RISK OF HEATBURSTS IN A ZONE FORECAST. HOWEVER LOOKING
AT ALL OF THE DATA...THE SETUP TONIGHT LOOKS VERY FAVORABLE FOR
PERIOD OF GUSTY SOUTH WINDS BENEATH ELEVATED RADAR ECHOES. WE
SHALL SEE.
A STRONG SHORTWAVE TROUGH WILL ROTATE THROUGH THE SOUTHERN PLAINS
TOMORROW AND WILL PUSH THE DRYLINE FARTHER TO THE EAST INTO THE NW
ZONES. WITH DAYTIME HEATING...CIN SHOULD BE LOW ENOUGH OVER THE NW
ZONES FOR ISOLATED SEVERE STORMS TO DEVELOP IN THE AFTERNOON.
WIND FIELDS WILL STRENGTHEN A BIT AND SUPERCELL STORM MOTION WILL
BE EASTERLY. WEST TO EAST STORM TRACKS ON SUNDAY EVENING MEANS
POPS WILL COVER THE AREAS NORTH OF I-20. LOW LEVEL HELICITY RAMPS
UP AROUND SUNSET SUNDAY EVENING AND IF SUPERCELLS CAN OVERCOME THE
WEAK CIN AND TAP INTO SURFACE PARCELS...A TORNADO THREAT WILL
EXIST. MONDAY LOOKS LIKE A CARBON COPY OF SUNDAY/S PATTERN WITH
THE MAIN FEATURES IN THE SAME PLACE...JUST A LITTLE WEAKER CIN SO
POPS ARE SLIGHTLY HIGHER/FARTHER SOUTH. TEMPS WILL REMAIN NEAR
PERSISTENCE AND WINDS WILL BE BREEZY SUNDAY AND MONDAY.
ON TUESDAY THE UPPER TROUGH WILL BEGIN TO FINALLY MOVE EAST AND
THIS WILL PUSH A COLD FRONT INTO THE NW ZONES TUESDAY AFTERNOON.
SCATTERED TO NUMEROUS STORMS SHOULD FIRE ALONG THE COLD FRONT
TUESDAY AFTERNOON AND WORK EAST AND SOUTHEAST ACROSS MUCH OF THE
AREA INTO TUESDAY NIGHT. RAINFALL MAY BE WIDESPREAD AND AVERAGE
1/2 TO 1 INCH. SEVERE WEATHER WILL BE A CONCERN GIVEN HIGH
INSTABILITY AND ADEQUATE DEEP LAYER SHEAR.
THE FRONT WILL PUSH THROUGH THE REGION AND DRIER AIR WILL END RAIN
CHANCES FROM NORTH TO SOUTH WEDNESDAY. LOW TEMPS WILL COOL A BIT
AND INTO THE 60S DUE TO THE LOWER DEWPOINTS...BUT HIGHS WILL
CONTINUE IN THE MID 80S TO NEAR 90 THROUGH THE REMAINDER OF THE
WEEK. WILL KEEP THE FORECAST DRY AS AN UPPER RIDGE SETTLES INTO
THE AREA...BUT WE MAY HAVE TO WATCH FOR NW FLOW MCS ACTIVITY ON
FRIDAY NIGHT IN THE NW ZONES. TOO FAR OUT TO RELY ON THE MODEL
FORECASTS FOR THIS POSSIBILITY AT THIS TIME.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 73 90 72 89 72 / 20 10 20 10 20
WACO, TX 72 90 73 90 73 / 10 5 5 5 10
PARIS, TX 70 88 70 87 70 / 20 10 20 10 40
DENTON, TX 73 90 71 89 70 / 20 10 20 20 30
MCKINNEY, TX 73 89 71 88 71 / 20 10 20 10 30
DALLAS, TX 75 91 74 90 74 / 20 10 20 10 20
TERRELL, TX 72 88 71 89 73 / 10 5 20 10 20
CORSICANA, TX 71 89 72 89 73 / 10 5 5 5 10
TEMPLE, TX 71 89 73 90 73 / 5 5 5 5 10
MINERAL WELLS, TX 71 93 70 92 71 / 20 20 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1223 PM CDT FRI MAY 17 2013
.AVIATION...
CONCERNS...RETURN OF MVFR CIGS LATE TONIGHT.
CURRENT MVFR CIGS ACROSS THE METROPLEX SHOULD GO SCT030-040 FOR
MOST TAF SITES EARLY THIS AFTERNOON WHILE KFTW/KAFW MAY REMAIN
BKN030 THROUGH 20Z. AFTERWARD...VFR CONDITIONS WITH SOUTHERLY
WINDS 13-20KTS. EXPECT ANOTHER ROUND OF STRATUS LATE TONIGHT
08-10Z THAT WILL PERSIST UNTIL 15Z. VFR SKIES LATE MORNING THROUGH
LATE SATURDAY AFTERNOON. SURFACE WINDS SHOULD BE SEVERAL KNOTS
HIGHER ON SATURDAY AFTERNOON THAN THIS AFTERNOON.
AS FOR CONVECTION...MIDDAY CONVECTION BETWEEN KCRS-KLFK-KUTS WILL
PERSIST SEVERAL MORE HOURS AS THE CELLS PROPAGATE SOUTHEAST.
OTHERWISE...FORECAST SOUNDINGS SHOW ALL FWD TAF SITES REMAINING
STRONGLY CAPPED THROUGH THE FORECAST PERIOD. HOWEVER...FAR TO THE
WEST...A DRYLINE WILL NEAR A KCDS-KABI- KSJT LINE THIS AFTERNOON
AND SHOULD BE ABLE TO PRODUCE SEVERAL SUPERCELL THUNDERSTORMS
BETWEEN 21-23Z. NONE ARE EXPECTED TO AFFECT OUR TAF SITES. 75
&&
.UPDATE...
12Z FWD SOUNDING DEPICTS NEARLY DRY ADIABATIC LAPSE RATES FROM
850MB UP TO 500MB. CURRENTLY A WEAK SHORTWAVE WAS MOVING ACROSS
NORTH TEXAS IN NORTHWEST FLOW ALOFT AND WAS RESPONSIBLE FOR THE
ELEVATED CONVECTION OCCURRING OVER THE SOUTHEAST ZONES THIS
MORNING. THESE STORMS HAVE PRODUCED HAIL UP TO GOLF BALL SIZE AND
ARE A TESTAMENT TO THE STEEP LAPSE RATES ALOFT. THIS SHORTWAVE
WILL CONTINUE TO MOVE SOUTHEAST AND OUT OF THE AREA BY MIDDAY.
STRONG SURFACE HEATING ACROSS THE WESTERN ZONES WILL HELP PUSH
TEMPERATURES TO NEAR THE CENTURY MARK THIS AFTERNOON. A DRY LINE
WILL REACH A LINE FROM GRAHAM TO COMANCHE TO LLANO. SHORT TERM
MODELS DEPICT DEWPOINTS IN THE LOW TO MID 70S AHEAD OF THE DRY
LINE...BUT THIS IS PROBABLY TOO HIGH. BELIEVE DEWPOINTS WILL MIX
OUT INTO THE UPPER 60S. NONETHELESS...THIS WILL CONTRIBUTE TO
EXTREME INSTABILITY WITH SURFACE BASED CAPE VALUES ABOVE 4000
J/KG. UNLIKE THE EVENT ON WEDNESDAY...THE CAP WILL BE MUCH
STRONGER TODAY AND WILL REQUIRE STRONG HEATING AND THE MESOSCALE
FORCING PROVIDED BY A DRY LINE TO BE OVERCOME. GIVEN A REASONABLE
FORECAST TEMP/DEWPOINT COMBINATION OF 99 OVER 68 AHEAD OF THE DRY
LINE...THIS SHOULD BE SUFFICIENT FOR THE CAP TO BREAK.
SEVERAL OF THE HI-RES CONVECTION ALLOWING MODELS AND THE LAST 2
RUNS OF THE NAM ARE SHOWING STORM INITIATION LATE THIS
AFTERNOON...AND ARE FOCUSING IN ON THE AREA NEAR THE LLANO
UPLIFT...WHICH WOULD AFFECT OUR SW ZONES AND ALSO ANOTHER AREA
NEAR GRAHAM AND BRECKENRIDGE. DEEP LAYER SHEAR IS NOT OVERLY
STRONG AND IS ON THE LOW END OF THE ALLOWABLE LEVEL FOR
SUPERCELLS. HOWEVER THE HIGH INSTABILITY WILL LIKELY COMPENSATE
AND ALLOW FOR SUPERCELL MODES. SUPERCELL STORM MOTION TECHNIQUES
BASED ONLY ON WIND PROFILES ARE EAST AT 10KT...BUT IN CASES OF
HIGH INSTABILITY AND WEAK FLOW...THESE SUPERCELLS WILL LIKELY HEAD
SLOWLY SOUTHEAST OR EVEN DUE SOUTH. GIANT HAIL...PERHAPS GREATER
THAN BASEBALLS WILL BE POSSIBLE WITH ANY SUPERCELL STORM.
SURFACE TEMPS WILL LIKELY REACH 105 WEST OF OUR CWA BEHIND THE
DRY LINE...WHICH SHOULD ALLOW A THERMAL SURFACE LOW TO INTENSIFY
TODAY. THIS WILL CAUSE LOW LEVEL WINDS TO BACK OVER THE NORTHERN
PART OF THE CWA...WHICH WILL ENHANCE LOW LEVEL DIRECTION SHEAR
PROFILES ACROSS THE NORTHWEST CWA DESPITE WIND SPEEDS REMAINING
FAIRLY WEAK AND LESS THAN 15KT AT ANY GIVEN LEVEL. STORM RELATIVE
0-3KM HELICITY VALUES BY THE RUC/NAM ARE FORECAST TO BE NEAR
100-150 MS/S2...SIGNIFICANTLY LESS THAN LAST WEDNESDAY...BUT AGAIN
THE HIGHER INSTABILITY CAN OFTEN COMPENSATE TO RAISE THE CONCERN
FOR TORNADOGENESIS. IN ADDITION SHOULD SUPERCELLS IN FACT MOVE
SOUTH...THESE MODEL VALUES OF 0-3 SRH VALUES ARE TOO LOW. HAVE
ADDED A RISK OF ISOLATED TORNADOES TO THE HWO AND GRAPHIC
FORECASTS AS WELL.
I SHOULD STRESS ALL OF THE SEVERE THREAT TODAY IS CONDITIONAL
BASED ON THE CAP BREAKING...WHICH AGAIN IS NOT GUARANTEED BUT IS
PROBABLE. WITH LESS HEATING ACROSS THE I-35 CORRIDOR...THIS SHOULD
KEEP SEVERE CONVECTION CONFINED TO THE WESTERN ZONES WITH THE CAP
TOO STRONG FOR SURFACE BASED CONVECTION IN THE CENTRAL AND EASTERN
ZONES. STILL IT IS POSSIBLE RESIDUAL ELEVATED CONVECTION OR ANVIL
PRECIPITATION MAY ENTER THE CENTRAL ZONES LATE TONIGHT...BUT WILL
KEEP POPS AT 10 PERCENT WITH NO MODEL SUPPORT FOR THIS SCENARIO.
FOR THE UPDATE HAVE LOWERED HIGHS IN THE SOUTHEAST ZONES DUE TO
MORNING RAIN AND CLOUDS. HAVE RAISED POPS IN THE WESTERN ZONES TO
REFLECT THE HIGHER POTENTIAL FOR STORMS THIS AFTERNOON AND EVENING.
TR.92
&&
.PREV DISCUSSION... /ISSUED 354 AM CDT FRI MAY 17 2013/
...A FEW SEVERE STORMS POSSIBLE ACROSS FAR WESTERN NORTH TEXAS BY
EACH EVENING TODAY AND SATURDAY...THEN NORTH OF I-20 LATE SUNDAY...
WEATHER FORECAST REMAINS CHALLENGING TODAY INTO THE WEEKEND. WE
CONTINUED TO SEE A SUBTLE SURFACE BOUNDARY SITUATED ALONG/NORTH OF
HWY 38 THIS MORNING AS EVIDENCED BY THE BACKED/LIGHTER EAST WINDS
AND LOWER SURFACE DEW POINTS THIS MORNING...WHILE STRONGER SSE
WINDS 10 TO 15 MPH WHERE OCCURRING FROM THE I-20 CORRIDOR INTO
CENTRAL TEXAS. SOME PATCHY DENSE FOG WAS OCCURRING ALONG THE RED
RIVER VALLEY...WHILE A SUBTLE DISTURBANCE WAS MOVING ACROSS WITHIN
THE UPPER RIDGE OVER THE TOP OF THE AREA. SOME AC/ACCAS WAS NOTED
ON INFRARED SATELLITE IMAGERY WITH STEEP LAPSE RATES ALOFT ON THE
00Z FWD SOUNDING AND MODELS. ISOLATED...ELEVATED/HIGH-BASED
SHOWERS AND STORMS ARE POSSIBLE THIS MORNING MAINLY ALONG AND
SOUTH OF THE I-20/I-30 CORRIDORS. LIGHTNING WILL BE THE MAIN
THREAT WITH ACTIVITY THIS MORNING WITH VERY LITTLE IN THE WAY OF
MEASURABLE RAINFALL EXPECTED.
THE SURFACE DRYLINE AND ASSOCIATED LOW PRESSURE OVER FAR WEST
TEXAS WILL CONTINUE TO DEEPEN AND SLIDE SLOWLY EAST TOWARD OUR FAR
W/SW COUNTIES LATE THIS AFTERNOON/EVE. STRONG MIXING AND HEATING
ALONG AND JUST AHEAD OF THIS FEATURE WILL HELP HIGHS SOAR WELL
INTO THE 90S WITH A FEW AREAS TOPPING THE CENTURY MARK WEST OF
I-35/I-35W. OUR CAPPING INVERSION WAS ELEVATED AND BASED ABOVE
800MB AND NOT OVERLY STOUT...SO DESPITE THE UPPER RIDGE ARRIVING
OVERHEAD...FEEL THE HOT TEMPS WILL MAKE IT BREAKABLE. HIGH-RES
WRF/ARW/AND HRRR MODELS ALL HINT AT ISOLATED STORM DEVELOPMENT JUST
W/SW OF OUR CWA AT PEAK HEATING AND POTENTIALLY AFFECTING OUR FAR
WSW COUNTIES BETWEEN 4 PM AND SUNSET. INSTABILITY WILL BE VERY HIGH
WITH MODELS SHOWING 3500-5000 J/KG SBCAPE OR POSSIBLY MORE WITH
VERY STEEP MID LEVEL LAPSE RATES OVER 8 DEG C/KM. ANY ISOLATED
STORMS THAT OCCUR WILL LIKELY BE SEVERE WITH VERY LARGE HAIL AND
DAMAGING DOWNBURSTS. DESPITE SURFACE DEW POINTS BEING NEAR 70
DEGREES...THE HOT TEMPERATURES WILL RESULT IN RELATIVELY HIGH
BASES AND A LOWER TORNADO THREAT THAN A FEW DAYS AGO. WITH THE
UPPER RIDGE OVERHEAD...STORMS WILL DIMINISH IN STRENGTH OR
DISSIPATE RAPIDLY AROUND SUNSET WITH LOSS OF HEATING AND THE CAP
INTENSIFYING QUICKLY BY LATE EVENING.
THE UPPER RIDGE SHIFTS EAST OF THE AREA ON SATURDAY WITH LONGWAVE
UPPER TROUGH SNAKING OVER THE ROCKIES INTO THE WESTERN HIGH
PLAINS. THE DRYLINE WILL ACTUALLY MAKE A STRONGER PUSH TOWARD OUR
FAR WESTERN COUNTIES BY EARLY EVENING SATURDAY WITH A LITTLE
BETTER UPPER SUPPORT. INSTABILITY WILL BE VERY STRONG ONCE AGAIN
WITH ISOLATED TO SCATTERED STRONG TO SEVERE STORMS EXPECTED MAINLY
ALONG AND WEST OF HWY 281...THEN DIMINISHING QUICKLY AFTER SUNSET
WITH THE CAP INTENSIFYING ONCE AGAIN. THE UPPER TROUGH DAMPENS
OVER THE CONUS ON SUNDAY WITH STRONG WESTERLY FLOW ALOFT OCCURRING
FROM THE RED RIVER VALLEY NORTH THROUGH THE CENTRAL PLAINS. HAVE
MODIFIED BEST CHANCES TO OCCUR NORTH OF I-20 AND INTO THE RED
RIVER VALLEY...WITH THE CAP BEING MUCH STRONGER OVER THE SOUTH.
DIURNAL SEVERE WEATHER WILL BE POSSIBLE AGAIN...BUT CONFIDENCE IS
LOWER FOR LATE SUNDAY DUE TO UNCERTAINTIES REGARDING CAP STRENGTH
AND SOUTHERN EXTENT OF FORCING. THE BEST SURFACE FOCUS WILL BE
ALONG A COLD FRONT THAT IS EXPECTED TO BE WELL TO THE NORTHWEST OF
THE AREA AS WELL.
OTHERWISE IN THE EXTENDED...STAYED WITH PERSISTENCE WITH THE
PREVIOUS FORECAST WITH LOW POPS RETURNING BY MID WEEK WITH A COLD
FRONT WEAKENING AND STALLING ACROSS THE NORTHWEST COUNTIES. A
SHORTWAVE TROUGH WILL BE MOVING OVER THE CENTRAL AND SOUTHERN
PLAINS AT THIS TIME AS WELL. IT IS TOO EARLY TO ASSESS ANY SEVERE
WEATHER THREAT THIS FAR OUT...BUT WILL CONTINUE TO ASSESS THESE
POSSIBILITIES IN THE COMING DAYS AHEAD. 05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 89 72 93 72 88 / 10 10 5 10 10
WACO, TX 91 71 92 71 90 / 10 10 5 10 10
PARIS, TX 82 68 86 69 86 / 10 10 10 10 10
DENTON, TX 86 70 93 71 89 / 10 10 10 10 20
MCKINNEY, TX 84 69 91 69 88 / 10 10 5 10 10
DALLAS, TX 88 72 93 72 90 / 10 10 5 10 10
TERRELL, TX 87 69 90 70 89 / 10 10 5 10 10
CORSICANA, TX 89 70 91 70 89 / 40 10 5 10 10
TEMPLE, TX 91 70 91 71 89 / 10 20 10 10 10
MINERAL WELLS, TX 94 70 96 70 93 / 10 20 10 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1035 AM CDT FRI MAY 17 2013
.UPDATE...
12Z FWD SOUNDING DEPICTS NEARLY DRY ADIABATIC LAPSE RATES FROM
850MB UP TO 500MB. CURRENTLY A WEAK SHORTWAVE WAS MOVING ACROSS
NORTH TEXAS IN NORTHWEST FLOW ALOFT AND WAS RESPONSIBLE FOR THE
ELEVATED CONVECTION OCCURRING OVER THE SOUTHEAST ZONES THIS
MORNING. THESE STORMS HAVE PRODUCED HAIL UP TO GOLF BALL SIZE AND
ARE A TESTAMENT TO THE STEEP LAPSE RATES ALOFT. THIS SHORTWAVE
WILL CONTINUE TO MOVE SOUTHEAST AND OUT OF THE AREA BY MIDDAY.
STRONG SURFACE HEATING ACROSS THE WESTERN ZONES WILL HELP PUSH
TEMPERATURES TO NEAR THE CENTURY MARK THIS AFTERNOON. A DRY LINE
WILL REACH A LINE FROM GRAHAM TO COMANCHE TO LLANO. SHORT TERM
MODELS DEPICT DEWPOINTS IN THE LOW TO MID 70S AHEAD OF THE DRY
LINE...BUT THIS IS PROBABLY TOO HIGH. BELIEVE DEWPOINTS WILL MIX
OUT INTO THE UPPER 60S. NONETHELESS...THIS WILL CONTRIBUTE TO
EXTREME INSTABILITY WITH SURFACE BASED CAPE VALUES ABOVE 4000
J/KG. UNLIKE THE EVENT ON WEDNESDAY...THE CAP WILL BE MUCH
STRONGER TODAY AND WILL REQUIRE STRONG HEATING AND THE MESOSCALE
FORCING PROVIDED BY A DRY LINE TO BE OVERCOME. GIVEN A REASONABLE
FORECAST TEMP/DEWPOINT COMBINATION OF 99 OVER 68 AHEAD OF THE DRY
LINE...THIS SHOULD BE SUFFICIENT FOR THE CAP TO BREAK.
SEVERAL OF THE HI-RES CONVECTION ALLOWING MODELS AND THE LAST 2
RUNS OF THE NAM ARE SHOWING STORM INITIATION LATE THIS
AFTERNOON...AND ARE FOCUSING IN ON THE AREA NEAR THE LLANO
UPLIFT...WHICH WOULD AFFECT OUR SW ZONES AND ALSO ANOTHER AREA
NEAR GRAHAM AND BRECKENRIDGE. DEEP LAYER SHEAR IS NOT OVERLY
STRONG AND IS ON THE LOW END OF THE ALLOWABLE LEVEL FOR
SUPERCELLS. HOWEVER THE HIGH INSTABILITY WILL LIKELY COMPENSATE
AND ALLOW FOR SUPERCELL MODES. SUPERCELL STORM MOTION TECHNIQUES
BASED ONLY ON WIND PROFILES ARE EAST AT 10KT...BUT IN CASES OF
HIGH INSTABILITY AND WEAK FLOW...THESE SUPERCELLS WILL LIKELY HEAD
SLOWLY SOUTHEAST OR EVEN DUE SOUTH. GIANT HAIL...PERHAPS GREATER
THAN BASEBALLS WILL BE POSSIBLE WITH ANY SUPERCELL STORM.
SURFACE TEMPS WILL LIKELY REACH 105 WEST OF OUR CWA BEHIND THE
DRY LINE...WHICH SHOULD ALLOW A THERMAL SURFACE LOW TO INTENSIFY
TODAY. THIS WILL CAUSE LOW LEVEL WINDS TO BACK OVER THE NORTHERN
PART OF THE CWA...WHICH WILL ENHANCE LOW LEVEL DIRECTION SHEAR
PROFILES ACROSS THE NORTHWEST CWA DESPITE WIND SPEEDS REMAINING
FAIRLY WEAK AND LESS THAN 15KT AT ANY GIVEN LEVEL. STORM RELATIVE
0-3KM HELICITY VALUES BY THE RUC/NAM ARE FORECAST TO BE NEAR
100-150 MS/S2...SIGNIFICANTLY LESS THAN LAST WEDNESDAY...BUT AGAIN
THE HIGHER INSTABILITY CAN OFTEN COMPENSATE TO RAISE THE CONCERN
FOR TORNADOGENESIS. IN ADDITION SHOULD SUPERCELLS IN FACT MOVE
SOUTH...THESE MODEL VALUES OF 0-3 SRH VALUES ARE TOO LOW. HAVE
ADDED A RISK OF ISOLATED TORNADOES TO THE HWO AND GRAPHIC
FORECASTS AS WELL.
I SHOULD STRESS ALL OF THE SEVERE THREAT TODAY IS CONDITIONAL
BASED ON THE CAP BREAKING...WHICH AGAIN IS NOT GARAUNTEED BUT IS
PROBABLE. WITH LESS HEATING ACROSS THE I-35 CORRIDOR...THIS SHOULD
KEEP SEVERE CONVECTION CONFINED TO THE WESTERN ZONES WITH THE CAP
TOO STRONG FOR SURFACE BASED CONVECTION IN THE CENTRAL AND EASTERN
ZONES. STILL IT IS POSSIBLE RESIDUAL ELEVATED CONVECTION OR ANVIL
PRECIPITATION MAY ENTER THE CENTRAL ZONES LATE TONIGHT...BUT WILL
KEEP POPS AT 10 PERCENT WITH NO MODEL SUPPORT FOR THIS SCENARIO.
FOR THE UPDATE HAVE LOWERED HIGHS IN THE SOUTHEAST ZONES DUE TO
MORNING RAIN AND CLOUDS. HAVE RAISED POPS IN THE WESTERN ZONES TO
REFLECT THE HIGHER POTENTIAL FOR STORMS THIS AFTERNOON AND EVENING.
TR.92
&&
.PREV DISCUSSION... /ISSUED 354 AM CDT FRI MAY 17 2013/
...A FEW SEVERE STORMS POSSIBLE ACROSS FAR WESTERN NORTH TEXAS BY
EACH EVENING TODAY AND SATURDAY...THEN NORTH OF I-20 LATE SUNDAY...
WEATHER FORECAST REMAINS CHALLENGING TODAY INTO THE WEEKEND. WE
CONTINUED TO SEE A SUBTLE SURFACE BOUNDARY SITUATED ALONG/NORTH OF
HWY 38 THIS MORNING AS EVIDENCED BY THE BACKED/LIGHTER EAST WINDS
AND LOWER SURFACE DEW POINTS THIS MORNING...WHILE STRONGER SSE
WINDS 10 TO 15 MPH WHERE OCCURRING FROM THE I-20 CORRIDOR INTO
CENTRAL TEXAS. SOME PATCHY DENSE FOG WAS OCCURRING ALONG THE RED
RIVER VALLEY...WHILE A SUBTLE DISTURBANCE WAS MOVING ACROSS WITHIN
THE UPPER RIDGE OVER THE TOP OF THE AREA. SOME AC/ACCAS WAS NOTED
ON INFRARED SATELLITE IMAGERY WITH STEEP LAPSE RATES ALOFT ON THE
00Z FWD SOUNDING AND MODELS. ISOLATED...ELEVATED/HIGH-BASED
SHOWERS AND STORMS ARE POSSIBLE THIS MORNING MAINLY ALONG AND
SOUTH OF THE I-20/I-30 CORRIDORS. LIGHTNING WILL BE THE MAIN
THREAT WITH ACTIVITY THIS MORNING WITH VERY LITTLE IN THE WAY OF
MEASURABLE RAINFALL EXPECTED.
THE SURFACE DRYLINE AND ASSOCIATED LOW PRESSURE OVER FAR WEST
TEXAS WILL CONTINUE TO DEEPEN AND SLIDE SLOWLY EAST TOWARD OUR FAR
W/SW COUNTIES LATE THIS AFTERNOON/EVE. STRONG MIXING AND HEATING
ALONG AND JUST AHEAD OF THIS FEATURE WILL HELP HIGHS SOAR WELL
INTO THE 90S WITH A FEW AREAS TOPPING THE CENTURY MARK WEST OF
I-35/I-35W. OUR CAPPING INVERSION WAS ELEVATED AND BASED ABOVE
800MB AND NOT OVERLY STOUT...SO DESPITE THE UPPER RIDGE ARRIVING
OVERHEAD...FEEL THE HOT TEMPS WILL MAKE IT BREAKABLE. HIGH-RES
WRF/ARW/AND HRRR MODELS ALL HINT AT ISOLATED STORM DEVELOPMENT JUST
W/SW OF OUR CWA AT PEAK HEATING AND POTENTIALLY AFFECTING OUR FAR
WSW COUNTIES BETWEEN 4 PM AND SUNSET. INSTABILITY WILL BE VERY HIGH
WITH MODELS SHOWING 3500-5000 J/KG SBCAPE OR POSSIBLY MORE WITH
VERY STEEP MID LEVEL LAPSE RATES OVER 8 DEG C/KM. ANY ISOLATED
STORMS THAT OCCUR WILL LIKELY BE SEVERE WITH VERY LARGE HAIL AND
DAMAGING DOWNBURSTS. DESPITE SURFACE DEW POINTS BEING NEAR 70
DEGREES...THE HOT TEMPERATURES WILL RESULT IN RELATIVELY HIGH
BASES AND A LOWER TORNADO THREAT THAN A FEW DAYS AGO. WITH THE
UPPER RIDGE OVERHEAD...STORMS WILL DIMINISH IN STRENGTH OR
DISSIPATE RAPIDLY AROUND SUNSET WITH LOSS OF HEATING AND THE CAP
INTENSIFYING QUICKLY BY LATE EVENING.
THE UPPER RIDGE SHIFTS EAST OF THE AREA ON SATURDAY WITH LONGWAVE
UPPER TROUGH SNAKING OVER THE ROCKIES INTO THE WESTERN HIGH
PLAINS. THE DRYLINE WILL ACTUALLY MAKE A STRONGER PUSH TOWARD OUR
FAR WESTERN COUNTIES BY EARLY EVENING SATURDAY WITH A LITTLE
BETTER UPPER SUPPORT. INSTABILITY WILL BE VERY STRONG ONCE AGAIN
WITH ISOLATED TO SCATTERED STRONG TO SEVERE STORMS EXPECTED MAINLY
ALONG AND WEST OF HWY 281...THEN DIMINISHING QUICKLY AFTER SUNSET
WITH THE CAP INTENSIFYING ONCE AGAIN. THE UPPER TROUGH DAMPENS
OVER THE CONUS ON SUNDAY WITH STRONG WESTERLY FLOW ALOFT OCCURRING
FROM THE RED RIVER VALLEY NORTH THROUGH THE CENTRAL PLAINS. HAVE
MODIFIED BEST CHANCES TO OCCUR NORTH OF I-20 AND INTO THE RED
RIVER VALLEY...WITH THE CAP BEING MUCH STRONGER OVER THE SOUTH.
DIURNAL SEVERE WEATHER WILL BE POSSIBLE AGAIN...BUT CONFIDENCE IS
LOWER FOR LATE SUNDAY DUE TO UNCERTAINTIES REGARDING CAP STRENGTH
AND SOUTHERN EXTENT OF FORCING. THE BEST SURFACE FOCUS WILL BE
ALONG A COLD FRONT THAT IS EXPECTED TO BE WELL TO THE NORTHWEST OF
THE AREA AS WELL.
OTHERWISE IN THE EXTENDED...STAYED WITH PERSISTENCE WITH THE
PREVIOUS FORECAST WITH LOW POPS RETURNING BY MID WEEK WITH A COLD
FRONT WEAKENING AND STALLING ACROSS THE NORTHWEST COUNTIES. A
SHORTWAVE TROUGH WILL BE MOVING OVER THE CENTRAL AND SOUTHERN
PLAINS AT THIS TIME AS WELL. IT IS TOO EARLY TO ASSESS ANY SEVERE
WEATHER THREAT THIS FAR OUT...BUT WILL CONTINUE TO ASSESS THESE
POSSIBILITIES IN THE COMING DAYS AHEAD.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 89 72 93 72 88 / 10 10 5 10 10
WACO, TX 91 71 92 71 90 / 10 10 5 10 10
PARIS, TX 82 68 86 69 86 / 10 10 10 10 10
DENTON, TX 86 70 93 71 89 / 10 10 10 10 20
MCKINNEY, TX 84 69 91 69 88 / 10 10 5 10 10
DALLAS, TX 88 72 93 72 90 / 10 10 5 10 10
TERRELL, TX 87 69 90 70 89 / 10 10 5 10 10
CORSICANA, TX 89 70 91 70 89 / 40 10 5 10 10
TEMPLE, TX 91 70 91 71 89 / 10 20 10 10 10
MINERAL WELLS, TX 94 70 96 70 93 / 10 20 10 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
354 AM CDT FRI MAY 17 2013
.DISCUSSION...
...A FEW SEVERE STORMS POSSIBLE ACROSS FAR WESTERN NORTH TEXAS BY
EACH EVENING TODAY AND SATURDAY...THEN NORTH OF I-20 LATE SUNDAY...
WEATHER FORECAST REMAINS CHALLENGING TODAY INTO THE WEEKEND. WE
CONTINUED TO SEE A SUBTLE SURFACE BOUNDARY SITUATED ALONG/NORTH OF
HWY 38 THIS MORNING AS EVIDENCED BY THE BACKED/LIGHTER EAST WINDS
AND LOWER SURFACE DEW POINTS THIS MORNING...WHILE STRONGER SSE
WINDS 10 TO 15 MPH WHERE OCCURRING FROM THE I-20 CORRIDOR INTO
CENTRAL TEXAS. SOME PATCHY DENSE FOG WAS OCCURRING ALONG THE RED
RIVER VALLEY...WHILE A SUBTLE DISTURBANCE WAS MOVING ACROSS WITHIN
THE UPPER RIDGE OVER THE TOP OF THE AREA. SOME AC/ACCAS WAS NOTED
ON INFRARED SATELLITE IMAGERY WITH STEEP LAPSE RATES ALOFT ON THE
00Z FWD SOUNDING AND MODELS. ISOLATED...ELEVATED/HIGH-BASED
SHOWERS AND STORMS ARE POSSIBLE THIS MORNING MAINLY ALONG AND
SOUTH OF THE I-20/I-30 CORRIDORS. LIGHTNING WILL BE THE MAIN
THREAT WITH ACTIVITY THIS MORNING WITH VERY LITTLE IN THE WAY OF
MEASURABLE RAINFALL EXPECTED.
THE SURFACE DRYLINE AND ASSOCIATED LOW PRESSURE OVER FAR WEST
TEXAS WILL CONTINUE TO DEEPEN AND SLIDE SLOWLY EAST TOWARD OUR FAR
W/SW COUNTIES LATE THIS AFTERNOON/EVE. STRONG MIXING AND HEATING
ALONG AND JUST AHEAD OF THIS FEATURE WILL HELP HIGHS SOAR WELL
INTO THE 90S WITH A FEW AREAS TOPPING THE CENTURY MARK WEST OF
I-35/I-35W. OUR CAPPING INVERSION WAS ELEVATED AND BASED ABOVE
800MB AND NOT OVERLY STOUT...SO DESPITE THE UPPER RIDGE ARRIVING
OVERHEAD...FEEL THE HOT TEMPS WILL MAKE IT BREAKABLE. HIGH-RES
WRF/ARW/AND HRRR MODELS ALL HINT AT ISOLATED STORM DEVELOPMENT JUST
W/SW OF OUR CWA AT PEAK HEATING AND POTENTIALLY AFFECTING OUR FAR
WSW COUNTIES BETWEEN 4 PM AND SUNSET. INSTABILITY WILL BE VERY HIGH
WITH MODELS SHOWING 3500-5000 J/KG SBCAPE OR POSSIBLY MORE WITH
VERY STEEP MID LEVEL LAPSE RATES OVER 8 DEG C/KM. ANY ISOLATED
STORMS THAT OCCUR WILL LIKELY BE SEVERE WITH VERY LARGE HAIL AND
DAMAGING DOWNBURSTS. DESPITE SURFACE DEW POINTS BEING NEAR 70
DEGREES...THE HOT TEMPERATURES WILL RESULT IN RELATIVELY HIGH
BASES AND A LOWER TORNADO THREAT THAN A FEW DAYS AGO. WITH THE
UPPER RIDGE OVERHEAD...STORMS WILL DIMINISH IN STRENGTH OR
DISSIPATE RAPIDLY AROUND SUNSET WITH LOSS OF HEATING AND THE CAP
INTENSIFYING QUICKLY BY LATE EVENING.
THE UPPER RIDGE SHIFTS EAST OF THE AREA ON SATURDAY WITH LONGWAVE
UPPER TROUGH SNAKING OVER THE ROCKIES INTO THE WESTERN HIGH
PLAINS. THE DRYLINE WILL ACTUALLY MAKE A STRONGER PUSH TOWARD OUR
FAR WESTERN COUNTIES BY EARLY EVENING SATURDAY WITH A LITTLE
BETTER UPPER SUPPORT. INSTABILITY WILL BE VERY STRONG ONCE AGAIN
WITH ISOLATED TO SCATTERED STRONG TO SEVERE STORMS EXPECTED MAINLY
ALONG AND WEST OF HWY 281...THEN DIMINISHING QUICKLY AFTER SUNSET
WITH THE CAP INTENSIFYING ONCE AGAIN. THE UPPER TROUGH DAMPENS
OVER THE CONUS ON SUNDAY WITH STRONG WESTERLY FLOW ALOFT OCCURRING
FROM THE RED RIVER VALLEY NORTH THROUGH THE CENTRAL PLAINS. HAVE
MODIFIED BEST CHANCES TO OCCUR NORTH OF I-20 AND INTO THE RED
RIVER VALLEY...WITH THE CAP BEING MUCH STRONGER OVER THE SOUTH.
DIURNAL SEVERE WEATHER WILL BE POSSIBLE AGAIN...BUT CONFIDENCE IS
LOWER FOR LATE SUNDAY DUE TO UNCERTAINTIES REGARDING CAP STRENGTH
AND SOUTHERN EXTENT OF FORCING. THE BEST SURFACE FOCUS WILL BE
ALONG A COLD FRONT THAT IS EXPECTED TO BE WELL TO THE NORTHWEST OF
THE AREA AS WELL.
OTHERWISE IN THE EXTENDED...STAYED WITH PERSISTENCE WITH THE
PREVIOUS FORECAST WITH LOW POPS RETURNING BY MID WEEK WITH A COLD
FRONT WEAKENING AND STALLING ACROSS THE NORTHWEST COUNTIES. A
SHORTWAVE TROUGH WILL BE MOVING OVER THE CENTRAL AND SOUTHERN
PLAINS AT THIS TIME AS WELL. IT IS TOO EARLY TO ASSESS ANY SEVERE
WEATHER THREAT THIS FAR OUT...BUT WILL CONTINUE TO ASSESS THESE
POSSIBILITIES IN THE COMING DAYS AHEAD.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 89 72 93 72 88 / 10 10 5 10 10
WACO, TX 92 71 92 71 90 / 20 10 5 10 10
PARIS, TX 82 68 86 69 86 / 10 10 10 10 10
DENTON, TX 86 70 93 71 89 / 10 10 10 10 20
MCKINNEY, TX 84 69 91 69 88 / 10 10 5 10 10
DALLAS, TX 88 72 93 72 90 / 10 10 5 10 10
TERRELL, TX 89 69 90 70 89 / 10 10 5 10 10
CORSICANA, TX 91 70 91 70 89 / 20 10 5 10 10
TEMPLE, TX 91 70 91 71 89 / 10 10 10 10 10
MINERAL WELLS, TX 94 70 96 70 93 / 10 10 10 10 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
724 PM CDT SAT MAY 18 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 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 724 PM CDT SAT MAY 18 2013
VFR CONDITIONS OVERNIGHT UNTIL A POSSIBLE LINE OF TSRA WILL AFFECT
THE TAFS FROM THE SOUTHWEST. SOME CAPE WILL BE AVAILABLE AS THIS
MOISTURE SURGE MOVES IN AND THUS HAVE INTRODUCED A VCTS INTO THE
TAF. THIS IS NOT A HIGH CONFIDENCE FORECAST BUT CONFIDENCE IS
INCREASING ON SOME WEATHER MOVING THROUGH AROUND DAYBREAK. IF THE
TSRA IN THE MORNING CONTINUES ON AN INCREASING TREND...WILL NEED
TO BRING IN SOME MVFR CONDITIONS WITH +RA. THE BETTER C HANCES FOR
TSRA ARE CLOSER TO KRST...THUS HAVE NOT INCLUDED TS AT KLSE IN
THE MORNING FORECAST.
THIS WEATHER WILL MOVE THROUGH IN THE MORNING AND A VFR IS EXPECTED
UNTIL AN AFTERNOON THREAT OF TSRA PRESENTS ITSELF. DETAILS ON
TIMING ARE OF LOW CONFIDENCE...AND MUCH WILL HINGE ON SURFACE
BOUDNARIES TO FORM THUNDERSTORMS. IT APPEARS THE EVENING PERIOD
AFTER THE TAF ENDING TIME WILL BE MORE WIDESPREAD TSRA. SEVERE
WEATHER IS ALSO POSSIBLE WITH DURING THE LATER AFTERNOON AND
EVENING PERIOD.
&&
.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 LA CROSSE WI
341 PM CDT FRI MAY 17 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 341 PM CDT FRI MAY 17 2013
LATEST SURFACE OBSERVATIONS PLACED A WARM FRONT EXTENDING FROM
BOOKINGS SOUTH DAKOTA...EXTENDING SOUTHEAST THROUGH SOUTHERN
MINNESOTA...TO NEAR FAIRMONT MINNESOTA...INTO EAST CENTRAL IOWA. THE
FRONT WAS NEARLY STATIONARY THIS AFTERNOON BUT WILL START TO SLOWLY
ADVANCE NORTHWARD TONIGHT. WATER VAPOR IMAGERY AND 500 MB RAP
ANALYSIS SHOWED AN ACTIVE PATTERN ACROSS THE CONUS. A VIGOROUS TROUGH
WAS DIVING INTO THE CENTRAL ROCKIES...PUSHING EAST. A SHORTWAVE WAS
MOVING ACROSS SOUTHERN MINNESOTA/NORTHERN THROUGH SOUTHERN WISCONSIN
AND WAS GENERATING A PERSISTENT BAND OF SHOWERS AND ISOLATED
THUNDERSTORMS. HEAVY RAIN HAS FALLEN ACROSS PORTIONS OF NORTH
CENTRAL IOWA INTO SOUTHEAST MINNESOTA.
KEEPING A VERY CLOSE WATCH ON THE WARM FRONT LATE THIS AFTERNOON INTO
THIS EVENING WITH ADDITIONAL SHOWER AND THUNDERSTORM DEVELOPMENT
EXPECTED ALONG IT. A CONVERGENT AREA WAS NOTED IN THE SURFACE WINDS
FIELDS OVER SOUTHWEST MINNESOTA...AND SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED ACROSS THESE AREAS. ALL OF THE MESOSCALE MODEL GUIDANCE IS
SUGGESTING THAT THIS AREA OF SHOWERS AND STORMS WILL CONTINUE AND
DRIFT SOUTHEAST ALONG THE FRONT LATE THIS AFTERNOON INTO THIS
EVENING. A VERY UNSTABLE AIRMASS IS FEEDING INTO THE WARM FRONT.
WHERE THERE HAS BEEN SUN THIS AFTERNOON...SURFACE BASES CAPE VALUES
HAVE CLIMBED TO AROUND 2000 J/KG. A RATHER MOIST AIRMASS IN PLACE
OVER THE AREA WITH PRECIPITABLE WATER VALUES OF 1.2 TO 1.3 INCHES.
THE SHOWERS AND THUNDERSTORMS HAVE BEEN VERY EFFICIENT RAIN
PRODUCERS TODAY AND WITH THIS MOIST AIRMASS IN PLACE...ANY
ADDITIONAL SHOWERS AND STORMS WOULD ALSO BE EFFICIENT RAIN
PRODUCERS. 0-6 KM SHEAR IS RATHER WEAK SO THINKING THE MAIN SEVERE
WEATHER THREAT WITH ANY THUNDERSTORMS TONIGHT WOULD BE PERIODS OF
HEAVY RAINFALL. CANNOT RULE OUT AN ISOLATED STORM OR TWO WITH LARGE
HAIL. THE MAIN CONCERN FOR THIS ACTIVITY IS ACROSS PORTIONS OF
SOUTHEAST MINNESOTA INTO NORTHEAST IOWA.
A THUNDERSTORM COMPLEX WILL FIRE OVER WESTERN SOUTH DAKOTA AND RACE
EAST TONIGHT. INSTABILITY REALLY WANES LATE THIS EVENING...WITH 0-3
KM MUCAPE VALUES FALLING TO 300 J/KG ACROSS SOUTHEAST MINNESOTA AND
NORTHEAST IOWA MAINLY AFTER 6Z TONIGHT. THINKING THE THUNDERSTORMS
WILL REALLY START TO DIE OFF WHEN THEY APPROACH THE INTERSTATE 35
CORRIDOR. THE STRONGEST 850 MB MOISTURE TRANSPORT STAYS FOCUSED INTO
EASTERN SOUTH DAKOTA THROUGH THE LATE NIGHT HOURS SO A WEAKENING
TREND SEEMS REASONABLE AND THE MESOSCALE MODELS ARE ALSO IN LINE
WITH THIS.
EARLY SATURDAY MORNING...THE WARM FRONT IS EXPECTED TO SLOWLY LIFT
NORTH OF THE INTERSTATE 90 CORRIDOR. CLOUD COVER OVER CENTRAL AND
NORTHERN WISCONSIN MAY SLOW ITS ADVANCE TO THE NORTH WITH THE COOLER
AIR UNDER CLOUD COVER TO THE NORTH AND SOME SUNSHINE SOUTH OF THE
WARM FRONT. FORECAST MODELS HAVE BEEN GENERATING SOME LIGHT PRECIPITATION
ACROSS AREAS RIGHT ALONG AND EAST OF THE MISSISSIPPI RIVER LATE
SATURDAY MORNING INTO SATURDAY AFTERNOON. THERE REALLY ISN/T ANY
APPRECIABLE FORCING ALOFT TO WORK WITH BUT FORECAST SOUNDINGS SHOW
CAPE VALUES INCREASING TO AROUND 1500 J/KG ACROSS PORTIONS OF
SOUTHEAST MINNESOTA AND TO AROUND 300 J/KG OVER NORTH CENTRAL
WISCONSIN. HAVE EXTENDED SHOWER/THUNDERSTORM CHANCES A BIT FURTHER
SOUTH OVER THE PREVIOUS FORECAST TO ACCOUNT FOR THE INSTABILITY AND
SLOWER MOVEMENT OF THE WARM FRONT. IT WILL BE RATHER WARM ON
SATURDAY IN THE WAKE OF THE WARM FRONT WITH HIGHS CLIMBING INTO THE
LOWER TO MID 80S OVER NORTHEAST IOWA...SOUTHEAST MINNESOTA AND FAR
WESTERN WISCONSIN. IT WILL BE A LITTLE COOLER ACROSS NORTH CENTRAL
WISCONSIN WHERE HIGHS WILL STRUGGLE TO GET OUT OF THE LOWER 70S.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 341 PM CDT FRI MAY 17 2013
A VERY ACTIVE PATTERN IS IN STORE FOR THE REGION SUNDAY THROUGH
MONDAY WITH SEVERE WEATHER POSSIBLE. THUNDERSTORMS FIRING OVER THE
DAKOTAS INTO THE CENTRAL PLAINS AND MOVING EAST INTO THE FORECAST
AREA SUNDAY MORNING WILL HAVE AN IMPACT ON CONVECTION FOR SUNDAY
AFTERNOON.
A POTENT SHORTWAVE EJECTS OUT OF THE CENTRAL PLAINS SUNDAY AFTERNOON
AND LIFTS NORTH INTO THE UPPER MISSISSIPPI RIVER VALLEY...BECOMING
NEGATIVELY TILTED. MEANWHILE...SURFACE LOW PRESSURE DEEPENS OVER
SOUTHEAST SOUTH DAKOTA...AND A SECONDARY WARM FRONT DEVELOPS OVER
NORTHERN IOWA AND LIFTS NORTH INTO SOUTHERN MINNESOTA EARLY SUNDAY
EVENING. 0-3KM MUCAPE VALUES INCREASE TO 1200-1500 J/KG LATE SUNDAY
AFTERNOON ACROSS NORTHERN IOWA/SOUTHERN MINNESOTA AND SOUTHWEST
WISCONSIN. 0-6 KM SHEAR INCREASES AS THE WAVE MOVES INTO THE
AREA...INCREASING TO 30 TO 45 KTS LATE SUNDAY AFTERNOON INTO SUNDAY
EVENING. MOST OF THIS SHEAR IS LOCATED IN THE 0-3 KM LAYER...OVERALL
RATHER IMPRESSIVE LOW LEVEL SHEAR PROFILES. LATEST THINKING IS THAT
THUNDERSTORMS WILL ERUPT OVER PORTIONS OF WESTERN IOWA SUNDAY
AFTERNOON WITH ADDITIONAL DEVELOP POSSIBLE TO THE NORTHEAST ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA....AND POTENTIALLY INTO
SOUTHWEST WISCONSIN. SHEAR PROFILES WOULD FAVOR SUPERCELL
STRUCTURES. SINCE MOST OF THE SHEAR IS LOCATED IN THE 0-3 KM
LAYER...THERE IS GROWING CONCERN FOR DAMAGING WINDS AND BOWING
STRUCTURES WITH THE STORMS. ISOLATED TORNADOES ARE ALSO POSSIBLE.
ALSO...THERE IS THE POTENTIAL FOR HEAVY RAINFALL...ESPECIALLY SUNDAY
EVENING AS 850 MB MOISTURE TRANSPORT INCREASES ACROSS NORTHERN
IOWA/SOUTHERN MINNESOTA AND SOUTHWEST WISCONSIN...FOCUSING INTO THE
WARM FRONT.
A BROAD UPPER TROUGH OVER THE UPPER MIDWEST WILL FINALLY CLOSE INTO
AN UPPER LOW ON MONDAY. SEVERAL PIECES OF ENERGY ROTATING AROUND THE
LOW WILL BRING ADDITIONAL CHANCE FOR SHOWERS AND THUNDERSTORMS TO
THE AREA. THINKING THE BULK OF THE INSTABILITY SHOULD BE SOUTHEAST
OF THE FORECAST AREA SO IT APPEARS THE GREATEST SEVERE THREAT SHOULD
BE SOUTHEAST OF THE AREA...BUT THIS WILL DEPEND ON HOW THE
CONVECTION PLAYS OUT SUNDAY NIGHT. THE UPPER LOW CONTINUES TO SPIN
OVER THE REIGON THROUGH MIDWEEK WITH DAILY CHANCES FOR SHOWERS AND
POSSIBLE THUNDERSTORMS.
&&
.AVIATION...TODAY AND TONIGHT
1130 AM CDT FRI MAY 17 2013
SFC FRONT LAYING WEST-EAST ACROSS SOUTHERN MN/WESTERN WI CONTINUES
TO BE A FOCUS FOR SHRA/ISOLD TS DEVELOPMENT LATE THIS MORNING. NOT
MUCH-IF ANY INSTABILITY OR LOW LEVEL MOISTURE TRANSPORT INTO THE
FRONT THOUGH...PER MESO MODELS. INDICATIONS THAT THE PCPN IS GETTING
SOME ENHANCEMENT ON ITS WESTERN EDGES FROM AN UPPER LEVEL SHORTWAVE
TROUGH...PER LATEST WATER VAPOR SATELLITE IMAGERY. THIS FEATURE IS
MOVING EAST...AND NAM12/HRRR SUGGEST THAT THE PCPN WILL MOVE WITH
IT. WILL TREND THE TAFS THIS WAY. THE HRRR DOES HINT THAT THE FRONT
WON/T MOVE TOO FAR NORTH THIS EVENING...AND COULD SERVE AS A FOCUS
FOR MORE SCT SHRA/TS. ARXLAPS ALSO HAS THIS POTENTIAL...WEST OF THE
MISSISSIPPI RIVER. CONFIDENCE SHAKY ON THIS POSSIBILITY...AND WILL
LIKELY LEAVE OUT OF THE KRST TAF FOR NOW.
WITH THE PROLONGED PERIOD OF RAIN MOISTENING THE BOUNDARY LAYER FOR
KRST/KLSE...FOG/STRATUS BECOMES A CONCERN OVERNIGHT. KLSE LIKELY
DECOUPLES RESULTING IN LIGHT/VRB WINDS. KRST PROBABLY STICKS AROUND
6-8KTS FROM THE ESE. NUMERICAL GUIDANCE AND BUFKIT SOUNDINGS POINT
TO GOOD SATURATION UNDER THE NOCTURNAL INVERSION THAT VSBY
RESTRICTIONS ARE LIKELY...ALONG WITH LOW STRATUS. MVFR/IFR
CONDITIONS ARE FAVORED INTO SATURDAY MORNING.
&&
.HYDROLOGY...THIS EVENING THROUGH MONDAY
ISSUED AT 341 PM CDT FRI MAY 17 2013
PERIODS OF SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF SOUTHEAST
MINNESOTA INTO NORTHEAST IOWA HAVE PRODUCED 2 TO NEARLY 2 1/2
INCHES OF RAINFALL SO FAR TODAY. SCATTERED THUNDERSTORMS ARE
EXPECTED LATE THIS AFTERNOON INTO EARLY THIS EVENING. THE STORMS
ARE SLOW MOVING AND WILL HAVE THE POTENTIAL TO PRODUCE PERIODS OF
HEAVY RAINFALL...WHICH COULD LEAD TO FLOODING...ESPECIALLY ACROSS
THOSE AREAS THAT HAVE ALREADY SEEN HEAVY RAINFALL.
THUNDERSTORMS ARE EXPECTED SUNDAY AFTERNOON THROUGH MONDAY. THE
STORMS COULD PRODUCE PERIODS OF HEAVY RAINFALL WHICH COULD LEAD TO
FLOODING. 1 TO 3 INCHES OF ADDITIOANL RAINFALL IS POSSIBLE FROM
SUNDAY INTO WEDNESDAY. A FLASH FLOOD WATCH MAY BE NEEDED IF
CONFIDENCE INCREASES ON WHERE THE HEAVIEST RAIN WILL FALL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION.....RIECK
HYDROLOGY...WETENKAMP
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1234 PM CDT FRI MAY 17 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 346 AM CDT FRI MAY 17 2013
FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THROUGH THE PERIOD.
WARM FRONT EXTENDS EAST OUT OF NE INTO NORTHERN IL. ONGOING PCPN
OVER IA/MN BORDER...NOW EDGING INTO WESTERN WI. CLOUDS HAVE KEPT
TEMPS UP OVERNIGHT OVER MUCH OF CWA...WITH ONLY THE FAR NORTH
FALLING INTO THE UPPER 30S. EASTERLY WINDS OVER WI...STILL
USHERING IN DRY AIR WITH DEW POINTS IN THE 30S. THIS HAS SLOWED
ADVANCE OF PCPN...THOUGH HIGH BASED...THE RETURNS ARE INCREASING
OVER THE STATE.
HAVE CONTINUED TREND OF EVENING FORECASTER TO SHIFT PCPN SOUTH
INTO CENTRAL AND EAST CENTRAL WI LATER THIS MORNING...THEN SHIFT
NORTH TONIGHT AND SAT AS WARM FRONT LIFTS NORTH/RIDGE BUILDS IN.
HAVE TRENDED TOWARDS MESO MODELS LIKE HRRR FOR DAY 1 PCPN TRENDS.
PCPN FOCUS ASSOCIATED WITH INCREASING ISENTROPIC LIFT/FGEN FORCING
WITH 850 BAROCLINIC ZONE OVER STATE.
HAVE STAYED WITH JUST SHOWER MENTION THROUGH TODAY AS INSTABILITY
MISSING OVER EASTERN WI...BRINGING IN SLIGHT CHANCE LATER TONIGHT
AND SATURDAY AS LOW LEVEL MOISTURE INCREASES AND STEEPER MID
LEVEL LAPSE RATES SHIFT EAST.
TEMPS TODAY TO BE HELD BACK BY CLOUDS AND EAST FLOW THUS STAYED
WITH UPPER 50S AND LOWER 60S THROUGHOUT CWA. MAX TEMPS BACK TO
NORMAL OR ABOVE ON SAT...EXCEPT EAST WITH CONTINUED EASTERLY COMPONENT.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 346 AM CDT FRI MAY 17 2013
THE MAIN CONCERN DURING THE LONG TERM IS TIMING PRECIPITATION INTO
THE AREA. A FRONTAL BOUNDARY IS FORECAST TO PUSH NORTHEAST THROUGH
WISCONSIN EARLY NEXT WEEK. SURFACE FLOW WILL BE OFF LAKE MICHIGAN
BETWEEN HIGH PRESSURE TO THE EAST AND THE FRONT...BUT
PRECIPITATION WILL MOVE IN AS THE FRONT PASSES AND THE SURFACE LOW
TO THE WEST GETS CLOSER TO WISCONSIN. HAVE A DRY FORECAST FOR
SATURDAY NIGHT BUT WENT WITH CHANCE POPS FOR CENTRAL AND NORTH
CENTRAL WISCONSIN SUNDAY.
HAVE AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS GOING THROUGH
THE MIDDLE OF NEXT WEEK AS THE SURFACE LOW AND UPPER LEVEL CYCLONE
PASS TO THE EAST OF THE AREA.
TEMPERATURES SHOULD REMAIN ABOVE NORMAL THROUGH THE EARLY PART OF
NEXT WEEK BEFORE A SURFACE RIDGE MOVES INTO THE REGION BRINGING
COOLER THAN NORMAL TEMPERATURES FOR THE LATTER HALF OF THE WEEK.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1230 PM CDT FRI MAY 17 2013
WARM FRONT TO THE SOUTH OF THE STATE WILL CONTINUE TO TRIGGER
SHOWERS FOR THE REST OF THE AFTERNOON INTO TONIGHT...AND
POSSIBLY SATURDAY MORNING ACROSS THE NORTH. DO NOT SEE THE WARM
FRONT PUSHING NORTH TO FAST TONIGHT...SO LINGERING SHOWERS WILL
GRADUALLY SHIFT TO THE NORTH OR OTHER SHOWERS AND STORMS THAT
DEVELOP ACROSS MINNESOTA MOVE EAST INTO THE AREA. VFR CIGS WILL
GIVE WAY TO MVFR AND POSSIBLY IFR CIGS LATER TONIGHT INTO EARLY
SATURDAY MORNING. ISOLATED THUNDERSTORMS ARE POSSIBLE TONIGHT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......ECKBERG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 AM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT FRI MAY 17 2013
FOCUS IS ON TRENDING CURRENT SHOWERS/STORMS ACROSS IA/MN...AND
CONVECTIVE PROBABILITIES LATER TODAY ALONG WARM FRONT.
LATEST RADAR SHOWS COMPLEX OF SHOWERS/STORMS ACROSS NORTHERN
IA/SOUTHERN MN...WHICH IS FEEDING OFF 850 MB LOW-LEVEL
JET...INTERACTING WITH A WARM FRONTAL BOUNDARY THAT STRETCHES ACROSS
NORTHERN IOWA. THESE STORMS ARE EFFICIENT HEAVY RAIN
PRODUCERS...GIVEN SLOW EASTWARD PROGRESS AND PWATS 1.4 TO 1.6
INCHES...WHICH IS 150 TO 180 PERCENT ABOVE NORMAL. THESE STORMS ARE
EXPECTED TO MOVE EASTWARD ACROSS SOUTHEAST MINNESOTA AND EXTREME
NORTHEAST IOWA...AND PARTS OF WESTERN WISCONSIN THROUGH MID/LATE
MORNING. SOME OF THE STRONGER CELLS COULD PRODUCE SMALL HAIL...BUT
NOT EXPECTING ANYTHING TO REACH SEVERE LIMITS. THE BIGGER IMPACT
WOULD BE LOCALIZED HEAVY RAINFALL...AND IN TOTAL...AMOUNTS BETWEEN 1
AND 2 INCHES ARE POSSIBLE.
THE BIG QUESTION FOR TODAY IS WHERE THE WARM FRONT ENDS UP...AND IF
ANOTHER ROUND OF SHOWERS/STORMS DEVELOPS ALONG IT THIS AFTERNOON.
LATEST RAP HAS A DECENT HANDLE RIGHT NOW...SHOWING THAT THE WARM
FRONT SETTLES ALONG THE IA/MN BORDER...AND INTO SOUTHWEST WISCONSIN
THIS AFTERNOON. ONGOING CONVECTION SHOULD KEEP NORTHWARD PROGRESS OF
THE BOUNDARY LIMITED SO RAP SOLUTION SEEMS REASONABLE. THE REMNANTS
OF THIS MORNING/S STORMS WOULD LIFT TO THE EAST/NORTHEAST...BUT
LEFTOVER OUTFLOW BOUNDARIES COMBINED WITH MODEST DAYTIME HEATING AND
A PASSING UPPER LEVEL SHORTWAVE LOOKS TO BE SUFFICIENT FOR
ADDITIONAL SHOWERS AND STORMS TO DEVELOP. THESE SHOWERS AGAIN
WOULD HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 350 AM CDT FRI MAY 17 2013
...SEVERE WEATHER EVENT POSSIBLE SUNDAY AND AGAIN ON MONDAY...
SATURDAY FEATURES UPPER LEVEL RIDGING ACROSS THE CENTRAL PLAINS AS
THE WEST COAST TROUGH CONTINUES TO MOVE EASTWARD. AT THE
SURFACE...LOW PRESSURE DEVELOPS IN THE LEE OF THE ROCKIES AND PUSHES
THE AFOREMENTIONED WARM FRONT WELL NORTH OF THE FORECAST AREA. THE
ATMOSPHERE BECOMES CAPPED FOR THE DAY...WITH THE WARM NOSE LAYER
EVIDENT IN THE 850 TO 750 MB LAYER. PLENTY OF ELEVATED CAPE NOTED
ACROSS THE AREA...ANYWHERE FROM 2000 TO 3000 J/KG BY SATURDAY
AFTERNOON. THE CAP REMAINS IN PLACE DURING THE DAY...BUT DOES WEAKEN
SOME BY LATE AFTERNOON AND EVENING AS CIN VALUES DROP TO LESS THAN
50 J/KG...MAINLY ALONG AND NORTH OF I-90. THE LACK OF A STRONG
FORCING MECHANISM SHOULD KEEP CONVECTIVE INITIATION PROBABILITIES
LOW...AND THIS IS WELL AGREED AMONG THE VARIOUS DETERMINISTIC
MODELS. THE ONLY EXCEPTION IS IN THE 17.00Z GFS WHERE A WEAK UPPER
LEVEL SHORTWAVE TROUGHS RIDES THE RIDGE ACROSS NORTHERN WISCONSIN.
THIS COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT TO BREAK THE WEAKER
CAP AND ALLOW SHOWERS/STORMS TO INITIATE. HAVE CONTINUED CHANCE POPS
MAINLY NORTH OF I-90 TO HIGHLIGHT THIS IDEA. ANY STORM CAPABLE OF
BREAKING THROUGH THE CAP AND BECOMING SURFACE BASED HAS THE
POTENTIAL TO PRODUCE LARGE HAIL AND POSSIBLY DAMAGING WINDS GIVEN
THE INSTABILITY AND 0-6 KM BULK SHEAR NEAR 30 KTS. OTHERWISE...WARM
DAY ON TAP WITH HIGHS IN THE LOW TO MID 80S.
FOCUS TURNS TO THE POTENTIAL SEVERE WEATHER EVENT FOR SUNDAY AS THE
AFOREMENTIONED UPPER LEVEL TROUGH BECOMES INCREASINGLY NEGATIVE
TILTED AND EJECTS INTO THE CENTRAL PLAINS BY 12Z SUNDAY. THE BASE OF
THE TROUGH WILL LIKELY BE ACROSS OK/KS...BUT QUICKLY LIFTS NORTHEAST
TOWARD WESTERN IOWA BY 00Z MONDAY. AT THE SURFACE...LOW PRESSURE
LOOKS TO MOVE NORTHEASTWARD FROM NEBRASKA TO NEAR SIOUX FALLS
SD...AND A WARM FRONT SHOULD BE DRAPED ACROSS SOUTHWEST MINNESOTA
EAST/SOUTHEASTWARD INTO NORTHEAST IOWA. IT/S POSSIBLE THERE COULD BE
SOME DECAYING CONVECTION SUNDAY MORNING ACROSS WESTERN IOWA...AND
THIS COULD PLAY INTO HOW UNSTABLE THE ATMOSPHERE BECOMES LATER THAT
DAY ACROSS THE REGION. IN ANY RATE...MUCAPE VALUES ARE EXPECTED TO
RANGE 3000 TO 3500 J/KG AND 0-6 KM BULK SHEAR VALUES APPROACH 35 KTS
WEST OF THE MISSISSIPPI RIVER SUNDAY AFTERNOON AND EVENING. THE
MAJORITY OF THE SHEAR IS FOUND IN THE 0-3 KM LAYER WITH 25 KTS SEEN.
EVEN MORE EXCITING ARE THE 0-1 KM SHEAR PARAMETERS...WHICH IS AT
LEAST 20 KTS. FINALLY...THE AIRMASS ACROSS SOUTHEAST MINNESOTA AND
NORTHERN IOWA SUNDAY LOOKS TO BE SOMEWHAT JUICY WITH DEWPOINTS IN
THE 60S. HOW JUICY IS STILL A QUESTION GIVEN DETERMINISTIC MODELS
POOR HANDLING OF DEWPOINTS LATELY. 17.00Z NAM/GFS PUT UPPER 60S TO
EVEN NEAR 70F BY 21Z SUNDAY...WHICH SEEMS A BIT OVERDONE. ADJUSTING
SOUNDINGS TO WHAT COULD BE A MORE REALISTIC VALUE /LOW TO MID 60S/
BASED ON THE MOIST BIAS STILL YIELDS CAPE VALUES IN THE 1500 TO 2500
J/KG RANGE.
IN SHORT...ENVISION STORMS TO FIRE UP ACROSS CENTRAL IOWA INTO
SOUTHERN MINNESOTA BY EARLY AFTERNOON SUNDAY...THEN QUICK MOVE
EAST/NORTHEAST...LASTING INTO THE EVENING HOURS. THE HIGHER SEVERE
CHANCES ARE WEST OF THE MISSISSIPPI RIVER...AS STORMS WOULD WEAKEN
SOME MOVING INTO WISCONSIN BUT STILL COULD REMAIN SEVERE. ORGANIZED
DISCRETE STRONG/SEVERE STORMS WOULD BE THE PRIMARY MODE...MAINLY
SUPERCELLS...WITH A PREFERENCE TO THE RIGHT MOVERS GIVEN CLOCKWISE
CURVATURE SEEN IN THE HODOGRAPHS. THE MAIN THREATS LOOK TO BE VERY
LARGE HAIL AND DAMAGING WINDS BUT ALSO A FAVORABLE ENVIRONMENT FOR
TORNADOES GIVEN 0-1 KM BULK SHEAR /AT LEAST 20 KTS/ AND EHI /1.0 TO
3.0/. WILL HIGHLIGHT INCREASED THREAT ACROSS THE MANY PUBLIC
PRODUCTS /HWO...GRAPHICAST...NEWS STORY/. THOSE WITH PLANS SUNDAY
AFTERNOON/EVENING WILL NEED TO KEEP A VERY CLOSE EYE TO THE FORECAST.
ANOTHER ROUND OF STRONG/SEVERE STORMS IS POSSIBLE MONDAY EVENING AS
THE WHOLE SYSTEM SLOWLY EDGES EASTWARD. ANOTHER FAVORABLE SEVERE
WEATHER ENVIRONMENT WITH 0-6 KM MUCAPE PEGGED BETWEEN 2000 TO
3000 J/KG AND BULK SHEAR 30 TO 40 KTS. DEPENDING ON HOW MUCH
EASTWARD PROGRESSION OF THE WEATHER SYSTEM OCCURS MONDAY...A
GREATER PERCENTAGE OF THE FORECAST AREA COULD BE IN RISK FOR
SEVERE WEATHER. AT THIS TIME...HIGHER THREAT AREA LOOKS TO BE
ALONG AND SOUTH OF I-90.
MODEL TIMING DIFFERENCES CREEP UP BY TUESDAY...MAINLY IN HOW QUICKLY
THE UPPER LEVEL CLOSES OFF AND MOVES EAST OVER THE AREA. WIDE RANGE
OF POSSIBILITIES ON WHEN THE LOW MOVES OVERHEAD...WITH THE 17.00Z
GFS THE QUICKEST /TUESDAY/ AND THE ECMWF SLOWEST /WEDNESDAY/. FOR
NOW...PERIODIC SHOWERS/STORMS TUESDAY AND WEDNESDAY LOOK GOOD.
COOLER TEMPERATURES ALOFT AND THREAT OF SHOWERS SHOULD KEEP HIGHS ON
THE COOLER SIDE WEDNESDAY AND THURSDAY...5 TO 7 DEGREES BELOW
NORMALS.
&&
.AVIATION...TODAY AND TONIGHT
1130 AM CDT FRI MAY 17 2013
SFC FRONT LAYING WEST-EAST ACROSS SOUTHERN MN/WESTERN WI CONTINUES
TO BE A FOCUS FOR SHRA/ISOLD TS DEVELOPMENT LATE THIS MORNING. NOT
MUCH-IF ANY INSTABILITY OR LOW LEVEL MOISTURE TRANSPORT INTO THE
FRONT THOUGH...PER MESO MODELS. INDICATIONS THAT THE PCPN IS GETTING
SOME ENHANCEMENT ON ITS WESTERN EDGES FROM AN UPPER LEVEL SHORTWAVE
TROUGH...PER LATEST WATER VAPOR SATELLITE IMAGERY. THIS FEATURE IS
MOVING EAST...AND NAM12/HRRR SUGGEST THAT THE PCPN WILL MOVE WITH
IT. WILL TREND THE TAFS THIS WAY. THE HRRR DOES HINT THAT THE FRONT
WON/T MOVE TOO FAR NORTH THIS EVENING...AND COULD SERVE AS A FOCUS
FOR MORE SCT SHRA/TS. ARXLAPS ALSO HAS THIS POTENTIAL...WEST OF THE
MISSISSIPPI RIVER. CONFIDENCE SHAKY ON THIS POSSIBILITY...AND WILL
LIKELY LEAVE OUT OF THE KRST TAF FOR NOW.
WITH THE PROLONGED PERIOD OF RAIN MOISTENING THE BOUNDARY LAYER FOR
KRST/KLSE...FOG/STRATUS BECOMES A CONCERN OVERNIGHT. KLSE LIKELY
DECOUPLES RESULTING IN LIGHT/VRB WINDS. KRST PROBABLY STICKS AROUND
6-8KTS FROM THE ESE. NUMERICAL GUIDANCE AND BUFKIT SOUNDINGS POINT
TO GOOD SATURATION UNDER THE NOCTURNAL INVERSION THAT VSBY
RESTRICTIONS ARE LIKELY...ALONG WITH LOW STRATUS. MVFR/IFR
CONDITIONS ARE FAVORED INTO SATURDAY MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM....ZT
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
718 AM CDT FRI MAY 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT FRI MAY 17 2013
FOCUS IS ON TRENDING CURRENT SHOWERS/STORMS ACROSS IA/MN...AND
CONVECTIVE PROBABILITIES LATER TODAY ALONG WARM FRONT.
LATEST RADAR SHOWS COMPLEX OF SHOWERS/STORMS ACROSS NORTHERN
IA/SOUTHERN MN...WHICH IS FEEDING OFF 850 MB LOW-LEVEL
JET...INTERACTING WITH A WARM FRONTAL BOUNDARY THAT STRETCHES ACROSS
NORTHERN IOWA. THESE STORMS ARE EFFICIENT HEAVY RAIN
PRODUCERS...GIVEN SLOW EASTWARD PROGRESS AND PWATS 1.4 TO 1.6
INCHES...WHICH IS 150 TO 180 PERCENT ABOVE NORMAL. THESE STORMS ARE
EXPECTED TO MOVE EASTWARD ACROSS SOUTHEAST MINNESOTA AND EXTREME
NORTHEAST IOWA...AND PARTS OF WESTERN WISCONSIN THROUGH MID/LATE
MORNING. SOME OF THE STRONGER CELLS COULD PRODUCE SMALL HAIL...BUT
NOT EXPECTING ANYTHING TO REACH SEVERE LIMITS. THE BIGGER IMPACT
WOULD BE LOCALIZED HEAVY RAINFALL...AND IN TOTAL...AMOUNTS BETWEEN 1
AND 2 INCHES ARE POSSIBLE.
THE BIG QUESTION FOR TODAY IS WHERE THE WARM FRONT ENDS UP...AND IF
ANOTHER ROUND OF SHOWERS/STORMS DEVELOPS ALONG IT THIS AFTERNOON.
LATEST RAP HAS A DECENT HANDLE RIGHT NOW...SHOWING THAT THE WARM
FRONT SETTLES ALONG THE IA/MN BORDER...AND INTO SOUTHWEST WISCONSIN
THIS AFTERNOON. ONGOING CONVECTION SHOULD KEEP NORTHWARD PROGRESS OF
THE BOUNDARY LIMITED SO RAP SOLUTION SEEMS REASONABLE. THE REMNANTS
OF THIS MORNING/S STORMS WOULD LIFT TO THE EAST/NORTHEAST...BUT
LEFTOVER OUTFLOW BOUNDARIES COMBINED WITH MODEST DAYTIME HEATING AND
A PASSING UPPER LEVEL SHORTWAVE LOOKS TO BE SUFFICIENT FOR
ADDITIONAL SHOWERS AND STORMS TO DEVELOP. THESE SHOWERS AGAIN
WOULD HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 350 AM CDT FRI MAY 17 2013
...SEVERE WEATHER EVENT POSSIBLE SUNDAY AND AGAIN ON MONDAY...
SATURDAY FEATURES UPPER LEVEL RIDGING ACROSS THE CENTRAL PLAINS AS
THE WEST COAST TROUGH CONTINUES TO MOVE EASTWARD. AT THE
SURFACE...LOW PRESSURE DEVELOPS IN THE LEE OF THE ROCKIES AND PUSHES
THE AFOREMENTIONED WARM FRONT WELL NORTH OF THE FORECAST AREA. THE
ATMOSPHERE BECOMES CAPPED FOR THE DAY...WITH THE WARM NOSE LAYER
EVIDENT IN THE 850 TO 750 MB LAYER. PLENTY OF ELEVATED CAPE NOTED
ACROSS THE AREA...ANYWHERE FROM 2000 TO 3000 J/KG BY SATURDAY
AFTERNOON. THE CAP REMAINS IN PLACE DURING THE DAY...BUT DOES WEAKEN
SOME BY LATE AFTERNOON AND EVENING AS CIN VALUES DROP TO LESS THAN
50 J/KG...MAINLY ALONG AND NORTH OF I-90. THE LACK OF A STRONG
FORCING MECHANISM SHOULD KEEP CONVECTIVE INITIATION PROBABILITIES
LOW...AND THIS IS WELL AGREED AMONG THE VARIOUS DETERMINISTIC
MODELS. THE ONLY EXCEPTION IS IN THE 17.00Z GFS WHERE A WEAK UPPER
LEVEL SHORTWAVE TROUGHS RIDES THE RIDGE ACROSS NORTHERN WISCONSIN.
THIS COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT TO BREAK THE WEAKER
CAP AND ALLOW SHOWERS/STORMS TO INITIATE. HAVE CONTINUED CHANCE POPS
MAINLY NORTH OF I-90 TO HIGHLIGHT THIS IDEA. ANY STORM CAPABLE OF
BREAKING THROUGH THE CAP AND BECOMING SURFACE BASED HAS THE
POTENTIAL TO PRODUCE LARGE HAIL AND POSSIBLY DAMAGING WINDS GIVEN
THE INSTABILITY AND 0-6 KM BULK SHEAR NEAR 30 KTS. OTHERWISE...WARM
DAY ON TAP WITH HIGHS IN THE LOW TO MID 80S.
FOCUS TURNS TO THE POTENTIAL SEVERE WEATHER EVENT FOR SUNDAY AS THE
AFOREMENTIONED UPPER LEVEL TROUGH BECOMES INCREASINGLY NEGATIVE
TILTED AND EJECTS INTO THE CENTRAL PLAINS BY 12Z SUNDAY. THE BASE OF
THE TROUGH WILL LIKELY BE ACROSS OK/KS...BUT QUICKLY LIFTS NORTHEAST
TOWARD WESTERN IOWA BY 00Z MONDAY. AT THE SURFACE...LOW PRESSURE
LOOKS TO MOVE NORTHEASTWARD FROM NEBRASKA TO NEAR SIOUX FALLS
SD...AND A WARM FRONT SHOULD BE DRAPED ACROSS SOUTHWEST MINNESOTA
EAST/SOUTHEASTWARD INTO NORTHEAST IOWA. IT/S POSSIBLE THERE COULD BE
SOME DECAYING CONVECTION SUNDAY MORNING ACROSS WESTERN IOWA...AND
THIS COULD PLAY INTO HOW UNSTABLE THE ATMOSPHERE BECOMES LATER THAT
DAY ACROSS THE REGION. IN ANY RATE...MUCAPE VALUES ARE EXPECTED TO
RANGE 3000 TO 3500 J/KG AND 0-6 KM BULK SHEAR VALUES APPROACH 35 KTS
WEST OF THE MISSISSIPPI RIVER SUNDAY AFTERNOON AND EVENING. THE
MAJORITY OF THE SHEAR IS FOUND IN THE 0-3 KM LAYER WITH 25 KTS SEEN.
EVEN MORE EXCITING ARE THE 0-1 KM SHEAR PARAMETERS...WHICH IS AT
LEAST 20 KTS. FINALLY...THE AIRMASS ACROSS SOUTHEAST MINNESOTA AND
NORTHERN IOWA SUNDAY LOOKS TO BE SOMEWHAT JUICY WITH DEWPOINTS IN
THE 60S. HOW JUICY IS STILL A QUESTION GIVEN DETERMINISTIC MODELS
POOR HANDLING OF DEWPOINTS LATELY. 17.00Z NAM/GFS PUT UPPER 60S TO
EVEN NEAR 70F BY 21Z SUNDAY...WHICH SEEMS A BIT OVERDONE. ADJUSTING
SOUNDINGS TO WHAT COULD BE A MORE REALISTIC VALUE /LOW TO MID 60S/
BASED ON THE MOIST BIAS STILL YIELDS CAPE VALUES IN THE 1500 TO 2500
J/KG RANGE.
IN SHORT...ENVISION STORMS TO FIRE UP ACROSS CENTRAL IOWA INTO
SOUTHERN MINNESOTA BY EARLY AFTERNOON SUNDAY...THEN QUICK MOVE
EAST/NORTHEAST...LASTING INTO THE EVENING HOURS. THE HIGHER SEVERE
CHANCES ARE WEST OF THE MISSISSIPPI RIVER...AS STORMS WOULD WEAKEN
SOME MOVING INTO WISCONSIN BUT STILL COULD REMAIN SEVERE. ORGANIZED
DISCRETE STRONG/SEVERE STORMS WOULD BE THE PRIMARY MODE...MAINLY
SUPERCELLS...WITH A PREFERENCE TO THE RIGHT MOVERS GIVEN CLOCKWISE
CURVATURE SEEN IN THE HODOGRAPHS. THE MAIN THREATS LOOK TO BE VERY
LARGE HAIL AND DAMAGING WINDS BUT ALSO A FAVORABLE ENVIRONMENT FOR
TORNADOES GIVEN 0-1 KM BULK SHEAR /AT LEAST 20 KTS/ AND EHI /1.0 TO
3.0/. WILL HIGHLIGHT INCREASED THREAT ACROSS THE MANY PUBLIC
PRODUCTS /HWO...GRAPHICAST...NEWS STORY/. THOSE WITH PLANS SUNDAY
AFTERNOON/EVENING WILL NEED TO KEEP A VERY CLOSE EYE TO THE FORECAST.
ANOTHER ROUND OF STRONG/SEVERE STORMS IS POSSIBLE MONDAY EVENING AS
THE WHOLE SYSTEM SLOWLY EDGES EASTWARD. ANOTHER FAVORABLE SEVERE
WEATHER ENVIRONMENT WITH 0-6 KM MUCAPE PEGGED BETWEEN 2000 TO
3000 J/KG AND BULK SHEAR 30 TO 40 KTS. DEPENDING ON HOW MUCH
EASTWARD PROGRESSION OF THE WEATHER SYSTEM OCCURS MONDAY...A
GREATER PERCENTAGE OF THE FORECAST AREA COULD BE IN RISK FOR
SEVERE WEATHER. AT THIS TIME...HIGHER THREAT AREA LOOKS TO BE
ALONG AND SOUTH OF I-90.
MODEL TIMING DIFFERENCES CREEP UP BY TUESDAY...MAINLY IN HOW QUICKLY
THE UPPER LEVEL CLOSES OFF AND MOVES EAST OVER THE AREA. WIDE RANGE
OF POSSIBILITIES ON WHEN THE LOW MOVES OVERHEAD...WITH THE 17.00Z GFS
THE QUICKEST /TUESDAY/ AND THE ECMWF SLOWEST /WEDNESDAY/. FOR
NOW...PERIODIC SHOWERS/STORMS TUESDAY AND WEDNESDAY LOOK GOOD.
COOLER TEMPERATURES ALOFT AND THREAT OF SHOWERS SHOULD KEEP HIGHS ON
THE COOLER SIDE WEDNESDAY AND THURSDAY...5 TO 7 DEGREES BELOW
NORMALS.
&&
.AVIATION...TODAY AND TONIGHT
715 AM CDT FRI MAY 17 2013
BROAD SHIELD OF RAIN MOVING THROUGH THE TAF SITES EARLY THIS
MORNING. SOME MVFR CEILINGS AND VISIBILITY FOR A TIME...BUT
EXPECTING THE RAIN TO LET UP AND CONDITIONS TO IMPROVE BY MID
TO LATE MORNING. QUESTION THEN BECOMES ANY NEW CONVECTIVE
DEVELOPMENT FOR THE AFTERNOON. SOME OF THE MESOSCALE MODELS ARE
INDICATING SOME NEW DEVELOPMENT AS THE WARM FRONT PUSHES NORTHWARD
AND THE UPPER TROUGH EDGES EVER CLOSER. AT THIS POINT IT IS
LOOKING LIKE ANY REDEVELOPMENT WILL BE SPOTTY...AND MAY MISS THE
TAF SITES ALTOGETHER. THUS DID NOT INCLUDE IN THE 12Z VERSION.
WINDS SLACKEN TONIGHT...AND WITH A MOIST BOUNDARY LATER DUE TO
RAIN TODAY AND INCREASING MOIST ADVECTION...EXPECT FOG COULD
BECOME AN ISSUE. AT THIS POINT ADDED SOME MVFR FOG RESTRICTIONS
TO THE TAFS AFTER 08Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...MW
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
644 AM CDT FRI MAY 17 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 346 AM CDT FRI MAY 17 2013
FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THROUGH THE PERIOD.
WARM FRONT EXTENDS EAST OUT OF NE INTO NORTHERN IL. ONGOING PCPN
OVER IA/MN BORDER...NOW EDGING INTO WESTERN WI. CLOUDS HAVE KEPT
TEMPS UP OVERNIGHT OVER MUCH OF CWA...WITH ONLY THE FAR NORTH
FALLING INTO THE UPPER 30S. EASTERLY WINDS OVER WI...STILL
USHERING IN DRY AIR WITH DEW POINTS IN THE 30S. THIS HAS SLOWED
ADVANCE OF PCPN...THOUGH HIGH BASED...THE RETURNS ARE INCREASING
OVER THE STATE.
HAVE CONTINUED TREND OF EVENING FORECASTER TO SHIFT PCPN SOUTH
INTO CENTRAL AND EAST CENTRAL WI LATER THIS MORNING...THEN SHIFT
NORTH TONIGHT AND SAT AS WARM FRONT LIFTS NORTH/RIDGE BUILDS IN.
HAVE TRENDED TOWARDS MESO MODELS LIKE HRRR FOR DAY 1 PCPN TRENDS.
PCPN FOCUS ASSOCIATED WITH INCREASING ISENTROPIC LIFT/FGEN FORCING
WITH 850 BAROCLINIC ZONE OVER STATE.
HAVE STAYED WITH JUST SHOWER MENTION THROUGH TODAY AS INSTABILITY
MISSING OVER EASTERN WI...BRINGING IN SLIGHT CHANCE LATER TONIGHT
AND SATURDAY AS LOW LEVEL MOISTURE INCREASES AND STEEPER MID
LEVEL LAPSE RATES SHIFT EAST.
TEMPS TODAY TO BE HELD BACK BY CLOUDS AND EAST FLOW THUS STAYED
WITH UPPER 50S AND LOWER 60S THROUGHOUT CWA. MAX TEMPS BACK TO
NORMAL OR ABOVE ON SAT...EXCEPT EAST WITH CONTINUED EASTERLY COMPONENT.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 346 AM CDT FRI MAY 17 2013
THE MAIN CONCERN DURING THE LONG TERM IS TIMING PRECIPITATION INTO
THE AREA. A FRONTAL BOUNDARY IS FORECAST TO PUSH NORTHEAST THROUGH
WISCONSIN EARLY NEXT WEEK. SURFACE FLOW WILL BE OFF LAKE MICHIGAN
BETWEEN HIGH PRESSURE TO THE EAST AND THE FRONT...BUT
PRECIPITATION WILL MOVE IN AS THE FRONT PASSES AND THE SURFACE LOW
TO THE WEST GETS CLOSER TO WISCONSIN. HAVE A DRY FORECAST FOR
SATURDAY NIGHT BUT WENT WITH CHANCE POPS FOR CENTRAL AND NORTH
CENTRAL WISCONSIN SUNDAY.
HAVE AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS GOING THROUGH
THE MIDDLE OF NEXT WEEK AS THE SURFACE LOW AND UPPER LEVEL CYCLONE
PASS TO THE EAST OF THE AREA.
TEMPERATURES SHOULD REMAIN ABOVE NORMAL THROUGH THE EARLY PART OF
NEXT WEEK BEFORE A SURFACE RIDGE MOVES INTO THE REGION BRINGING
COOLER THAN NORMAL TEMPERATURES FOR THE LATTER HALF OF THE WEEK.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 637 AM CDT FRI MAY 17 2013
AREA OF PRECIPITATION HAS MOVE EAST OUT OF IOWA INTO CENTRAL WI AT
THIS TIME. SOME QUESTION ON HOW FAR NORTH PCPN WILL GET THIS
MORNING GIVEN DRY AIR LEFT OVER FROM DEPARTING HIGH PRESSURE.
FORECAST TREND IS FOR THIS AREA TO AFFECT SOUTHERN TAF SITES WITH
MORE SHOWER ACTIVITY FORMING WEST AND LIFTING NORTH AS WARM FRONT
OVER THE PLAINS MOVES NORTH. BEST INSTABILITY TO SAY WELL SOUTH OF
AREA SO WILL NOT MENTION THUNDER. DRY LOW LEVEL FLOW EXPECTED TO
KEEP CIGS IN VFR CAT OR HIGH MVFR IS SOMW SHOWERS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......TE
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 346 AM CDT FRI MAY 17 2013
FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THROUGH THE PERIOD.
WARM FRONT EXTENDS EAST OUT OF NE INTO NORTHERN IL. ONGOING PCPN
OVER IA/MN BORDER...NOW EDGING INTO WESTERN WI. CLOUDS HAVE KEPT
TEMPS UP OVERNIGHT OVER MUCH OF CWA...WITH ONLY THE FAR NORTH
FALLING INTO THE UPPER 30S. EASTERLY WINDS OVER WI...STILL
USHERING IN DRY AIR WITH DEW POINTS IN THE 30S. THIS HAS SLOWED
ADVANCE OF PCPN...THOUGH HIGH BASED...THE RETURNS ARE INCREASING
OVER THE STATE.
HAVE CONTINUED TREND OF EVENING FORECASTER TO SHIFT PCPN SOUTH
INTO CENTRAL AND EAST CENTRAL WI LATER THIS MORNING...THEN SHIFT
NORTH TONIGHT AND SAT AS WARM FRONT LIFTS NORTH/RIDGE BUILDS IN.
HAVE TRENDED TOWARDS MESO MODELS LIKE HRRR FOR DAY 1 PCPN TRENDS.
PCPN FOCUS ASSOCIATED WITH INCREASING ISENTROPIC LIFT/FGEN FORCING
WITH 850 BAROCLINIC ZONE OVER STATE.
HAVE STAYED WITH JUST SHOWER MENTION THROUGH TODAY AS INSTABILITY
MISSING OVER EASTERN WI...BRINGING IN SLIGHT CHANCE LATER TONIGHT
AND SATURDAY AS LOW LEVEL MOISTURE INCREASES AND STEEPER MID
LEVEL LAPSE RATES SHIFT EAST.
TEMPS TODAY TO BE HELD BACK BY CLOUDS AND EAST FLOW THUS STAYED
WITH UPPER 50S AND LOWER 60S THROUGHOUT CWA. MAX TEMPS BACK TO
NORMAL OR ABOVE ON SAT...EXCEPT EAST WITH CONTINUED EASTERLY COMPONENT.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 346 AM CDT FRI MAY 17 2013
THE MAIN CONCERN DURING THE LONG TERM IS TIMING PRECIPITATION INTO
THE AREA. A FRONTAL BOUNDARY IS FORECAST TO PUSH NORTHEAST THROUGH
WISCONSIN EARLY NEXT WEEK. SURFACE FLOW WILL BE OFF LAKE MICHIGAN
BETWEEN HIGH PRESSURE TO THE EAST AND THE FRONT...BUT
PRECIPITATION WILL MOVE IN AS THE FRONT PASSES AND THE SURFACE LOW
TO THE WEST GETS CLOSER TO WISCONSIN. HAVE A DRY FORECAST FOR
SATURDAY NIGHT BUT WENT WITH CHANCE POPS FOR CENTRAL AND NORTH
CENTRAL WISCONSIN SUNDAY.
HAVE AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS GOING THROUGH
THE MIDDLE OF NEXT WEEK AS THE SURFACE LOW AND UPPER LEVEL CYCLONE
PASS TO THE EAST OF THE AREA.
TEMPERATURES SHOULD REMAIN ABOVE NORMAL THROUGH THE EARLY PART OF
NEXT WEEK BEFORE A SURFACE RIDGE MOVES INTO THE REGION BRINGING
COOLER THAN NORMAL TEMPERATURES FOR THE LATTER HALF OF THE WEEK.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1034 PM CDT THU MAY 16 2013
VFR CONDITIONS THROUGH FRIDAY MORNING. MVFR CIGS WITH
SHOWERS MAY BECOME MORE NUMEROUS MAINLY NORTH AND WEST OF THE FOX
VALLEY LATE FRIDAY MORNING INTO THE AFTERNOON HOURS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......TDH
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 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 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
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 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 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
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 GLASGOW MT
931 PM MDT SAT MAY 18 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
UPDATE...SHOWERS AND THUNDERSTORMS ARE CONTINUING TO AFFECT THE
CWA THIS EVENING. A FAIRLY CONCENTRATED AREA OF SHOWERS AND
THUNDERSTORMS PRODUCING HEAVY RAINFALL HAVE BEEN DRIFTING VERY
SLOWLY SOUTHEASTWARD ACROSS SOUTHERN MCCONE COUNTY. THIS PROMPTED
THE ISSUANCE OF A FLOOD ADVISORY THROUGH 11PM FOR POOR POOR DRAINAGE
AREAS NEAR HIGHWAYS 200 AND 253 NEAR BROCKWAY. IN FACT...A COUPLE OF
CALLS HAVE COME IN THIS EVENING DESCRIBING SOME FLOODING ON
HIGHWAY 253 NEAR BROCKWAY.
LATEST HRRR GUIDANCE HAS SHOWER AND THUNDERSTORM ACTIVITY
DIMINISHING SOME AS IT LIFTS NORTHWARD...BUT ALSO DEPICTS SOME
REDEVELOPMENT ACROSS SOME OF THE WESTERN PORTIONS OF THE CWA. THIS
HAS SOME SUPPORT FROM THE LATEST NAM AND THE 12Z ECMWF AS WELL SO
INCREASED POPS OVERNIGHT IN THESE AREAS. BUFKIT SOUNDINGS SHOWS
TOTAL TOTALS AROUND 50 AND LI BETWEEN 0 AND -1 FOR A LOT OF THE
CWA AROUND 06Z AND SO INCLUDED A MENTION OF THUNDER FOR THE REST
OF THE OVERNIGHT AS WELL. MALIAWCO
PREVIOUS SHORT TERM DISCUSSION...
A LARGE TROUGH HAS DUG IN OVER THE SOUTH WEST CONUS WITH A RIDGE
OVER WESTERN CANADA. VARIABLE IMPULSES OF ENERGY MOVING UP FROM
THE DOWNSTREAM PART OF THE SOUTHERN TROUGH WILL SUPPORT CONTINUED
PRECIPITATION THROUGH MONDAY AFTERNOON. RAINFALL IS ALSO SUPPORTED
BY A SURFACE LOW SOUTHEAST OF MONTANA THAT IS DRAWING LOW LEVEL
MOISTURE INTO THE AREA.
SYSTEM CONTINUES TO STRENGTHEN AND GRADUALLY MOVE EASTWARD...WITH
THE EFFECTS EXITING NORTHEAST MONTANA MONDAY NIGHT. ON
MONDAY...MOST OF THE MODELS HAVE MOST OF THE PRECIPITATION TO THE
SOUTHEAST PART OF THE CWA...BUT WITH POTENTIALLY HIGHER AMOUNTS
THAN EARLIER IN THE FORECAST. SOUNDINGS ARE VERY SATURATED WITH
AROUND AN INCH OF PRECIPITABLE WATER..LEADING TO THE FORECAST OF
MOSTLY RAIN SHOWERS. SOME INSTABILITY IN THE SOUNDINGS WILL LEAD
TO SOME LIMITED THUNDERSTORM ACTIVITY. THUNDERSTORMS ARE LIMITED
BY THE LACK OF CAP...WHICH WILL NOT ALLOW MUCH BUILD-UP OF
CONVECTIVE ENERGY. WINDS WILL PICK A LITTLE FROM THE NORTH ON
SUNDAY AS THE SURFACE LOW TIGHTENS...HOWEVER...THEY SHOULD STAY
BELOW 20KTS...WITH LOCALLY HIGHER GUSTS POSSIBLE IN OUTFLOW AREAS. MARTIN
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
THE ONLY CHANGES IN THE SHORT TERM LOOK TO BE STRONGER WINDS
THURSDAY AND THE POSSIBILITY FOR A SEVERE EVENT OR TWO AT THE END
OF THE PERIOD.
THE GFS WANTS TO RAMP UP WINDS QUITE A BIT THURSDAY AFTERNOON WITH
850 WINDS OVER THE CWA APPROACHING 50 KNOTS AS A MID LEVEL HIGH
OVER THE MINNESOTA AND ONTARIO REGION BATTLES WITH THE APPROACHING
PACIFIC NORTHWEST LOW. THE ECMWF HAS A BIT LESS AMPLIFIED GRADIENT
AND THUS A THINNER BAND OF STRONG 850 WINDS OVER THE CWA...BUT HAS
A SIMILAR UPPER PATTERN AS GFS. WENT CLOSER TO THE ECMWF SOLUTION
AS THE GFS TENDS TO HAVE WINDS A BIT HIGH OVER THE AREA.
AS THE UPPER LOW APPROACHES FOR THE WEEKEND...LOBES OF SHORTWAVE
ENERGY MAY CONTINUE TO BRING CHANCES FOR THUNDERSTORM DEVELOPMENT.
SATURDAY AFTERNOON HAS THE GFS AND ECMWF PUTTING OUT OVER 2000
J/KG OF CAPE OVER PARTS OF THE AREA...SO THERE WILL BE PLENTY OF
INSTABILITY OVER THE REGION. SUNDAY AFTERNOON AND EVENING SHOWS ROUGHLY
THE SAME SCENARIO...AND EVEN DIPS INTO MONDAY AS THE LOW SLOWLY
PROGRESSES NORTHWARD OFF TO OUR WEST AND NORTHWEST. THIS WILL
PROVIDE BROAD SOUTHWEST FLOW ALOFT FOR THE WEEKEND...WHICH SHOULD
GIVE ENOUGH UPPER LEVEL SUPPORT WITH DIFLUENT FLOW COMBINED WITH
LOBES OF SHORTWAVE ENERGY OFF THE MAIN FLOW...ESPECIALLY FOR
SATURDAY. FOR NOW...THE GFS HAS A WARM FRONT PASS THROUGH THE CWA
FRIDAY...AND THE ECMWF HAS ONE PASS SATURDAY. MORE MODEL AGREEMENT
ON TIMING WILL SHOW IF WE GET OUR FIRST SIGNIFICANT ROUND OF
STORMS THIS SEASON NEXT WEEKEND. BARNWELL
PREVIOUS LONG TERM DISCUSSION...THE EXTENDED FORECAST BEGINS
MONDAY NIGHT WITH AN UPPER LOW EXITING INTO THE UPPER MISSISSIPPI
RIVER VALLEY AND WEAK RIDGING BUILDING INTO NORTHEASTERN MONTANA.
BY WEDNESDAY MORNING ANOTHER UPPER LOW MOVES IN OVER THE PACIFIC
NORTHWEST SETTING UP DI-FLUENT SOUTHWEST FLOW ALOFT OVER THE AREA
THROUGH THE END OF THE EXTENDED.
THIS WILL CONTINUE THE COOLISH TEMPERATURES DURING THE DAY AND
NEAR NORMAL TEMPERATURES AT NIGHT. PRECIPITATION CHANCES SHOULD
RANGE SLIGHTLY ABOVE NORMAL... HOWEVER PIN POINTING ANY BETTER
DAYS THAN OTHERS WILL BE VERY HARD.
ENSEMBLES OF THE GFS AND EC SHOW HIGH CONFIDENCE IN AN UPPER LOW
OVER THE PACIFIC NORTHWEST...HOWEVER DO HAVE TROUBLE KEEPING THE
DAY TO DAY PLACEMENT OF THE UPPER LOW THE SAME. RMOP IS PRETTY
GOOD FOR UPPER LOWS OVER THE PACIFIC NORTHWEST. MODERATE TO HIGH
CONFIDENCE ON THE PATTERN. HOWEVER THE PATTERN IS MORE SHOWERY IN
NATURE NOT ALLOWING FOR THE CONFIDENCE TO DOUBLE OF CLIMO POPS AT
THIS TIME. PROTON
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED TO DETERIORATE TO MVFR AND POSSIBLY IFR
FOR KGDV AND KSDY LATER TONIGHT AS AN AREA OF SHOWERS AND
THUNDERSTORMS MOVE NORTHEAST INTO THESE AREAS. BETTER CONDITIONS
ARE EXPECTED FOR KGGW AND KOLF WHERE LIGHTER RAINS ARE EXPECTED
TONIGHT.
SINCE KOLF ASOS IS NOT TRANSMITTING..WE HAVE TAGGED THE TAF WITH
AMD NOT SKED. JAMBA
&&
.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 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 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 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
NWS SIOUX FALLS SD
1030 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 809 PM CDT SAT MAY 18 2013
WITH DEVELOPMENT OF CONVECTION ACROSS WESTERN NEBRASKA IN LAST 3
HOURS...HAVE BEEN ABLE TO SHARPEN SOME OF THE DETAILS IN THE
FORECAST OVER THE NEXT 18 TO 24H.
LARGE AREA OF SEVERE CONVECTION HAS DEVELOPED AROUND NORTH PLATTE
NEBRASKA...WITH ISOLATED NON SEVERE STORM TO THE NORTHEAST. SOME
OF THESE NONE SEVERE STORMS MAY MOVE INTO SOUTH CENTRAL SD BY 9
PM...WITH MLCAPES FROM 1500 TO 2000 J/KG...CANNOT RULE OUT SOME
LARGE HAIL BUT EFFECTIVE SHEAR REMAINS MARGINAL FOR SUPERCELL
DEVELOPMENT SO ANY HAIL LIKELY TO BE LESS THAN GOLF BALL SIZE. AS
CONVECTIVE LINE MOVES IN...THERE IS A FAVORABLE ALIGNMENT OF THE
0 TO 3 KM SHEAR VECTOR AND EXPECTED LINE ORIENTATION AS IT REACHES
SOUTH CENTRAL SD. IN ADDITION...SBCAPES FROM RAP SOUNDINGS ARE
STILL EXPECTED TO BE 1500 TO 2000 J/KG. EXPECT THAT THE QLCS WILL
BE ABLE TO USE THIS ENERGY TO MAINTAIN STRUCTURE AND WITH
FAVORABLE SHEAR THERE IS THE POTENTIAL FOR DAMAGING
WINDS...ESPECIALLY WEST OF I29 AND SOUTH OF I90 IN SE SD AND NE
NEBRASKA. A FEW OF THE STRONGER UPDRAFTS MAY ALSO CONTAIN 1 TO 1.5
INCH HAIL. AS THE NIGHT PROGRESSES THE DYNAMICS WILL BECOME A
LITTLE LESS FAVORABLE AND THERE WILL BE MORE CIN TO OVERCOME. AS A
RESULT...MOST OF THE CONVECTIVE ALLOWING MODELS...INCLUDING
HRRR...SHOW THAT THIS WILL MEAN A GRADUAL WEAKENING OF CONVECTION
WITH SEVERE RISK LIKELY DECREASING FAIRLY RAPIDLY BY 09Z OR SO.
HOWEVER,,,STILL ENOUGH ENERGY FOR THUNDERSTORMS TO CONTINUE AND AN
ISOLATED SEVERE WIND OR HAIL REPORT IS NOT OUT OF THE QUESTION AS
STORMS MOVE NORTH OF I90 AN EAST OF I29.
ONE OTHER THING LOOKS MORE CERTAIN IS THAT CONVECTION WILL MOVE
NORTHEAST A LITTLE FASTER THAN EARLIER EXPECTED AND MAY BE
NORTHEAST OF MARSHALL AND WINDOM BY 7 OR 8 AM ON SUNDAY. THIS MAY
ALLOW FOR SOME RECOVERY OF THE AIR MASS...ESPECIALLY IN NW IA AND
FAR SOUTHEAST SOUTH DAKOTA SUNDAY MORNING INTO EARLY AFTERNOON.
THEN A MUCH STRONGER WAVE WILL MOVE NORTH. HIGH RES NCAR ENSEMBLE
HAVE ALL MEMBERS SHOWING CONVECTION DEVELOPING IN EASTERN NEBRASKA
IN THE EARLY AFTERNOON AND MOVING NORTHEAST INTO NW IA DURING THE
AFTERNOON. RAP MODEL SOUNDINGS THAT HAVE NOT CONVECTED SHOW
MLCAPES EXCEEDING 3000 J/KG. WHILE THE 0 TO 6 KM SHEAR IS
MARGINAL...25 TO 30 KTS...THE 0 TO 1 KM SHEAR IS 15 TO 20 KTS. SO
WHILE NOT THE BEST SUPERCELL SET UP CANNOT COMPLETELY DISMISS THE
TORNADO THREAT TOMORROW IN NORTHWEST IOWA. BUT CERTAINLY LOOKS
LIKE ANOTHER THREAT FOR DAMAGING WINDS AND HAIL UP TO GOLF BALL
SIZE. SO HAVE INCREASED POPS IN NW IA AND SW MN TOMORROW
AFTERNOON.
UPDATED ZFP AND GRIDS OUT. WILL BE UPDATING HWO WITH LATEST
THINKING FOR BOTH TONIGHT AND SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 320 PM CDT SAT MAY 18 2013
AT THIS TIME...SURFACE TROUGH EXTENDS FROM NORTH CENTRAL SD TO WEST
CENTRAL NE. ALOFT...LARGE TROUGH EXISTS THROUGHOUT THE INTERMOUNTAIN
WEST WITH WATER VAPOR SHOWING A SHORT WAVE NEAR THE FOUR CORNERS
AREA. THE SHORT WAVE WILL LIFT EASTWARD TONIGHT INTO THE
SOUTHWESTERN PLAINS AREA. AT THE SURFACE...THERE ARE SOME
INDICATIONS THAT A SURFACE LOW WILL GENERATE IN SOUTH CENTRAL SOUTH
DAKOTA AS THE NIGHT PROGRESSES. THE LOW LEVEL JET INCREASES MODESTLY
MOSTLY INTO THE 25 TO 30 KNOT RANGE AT 850MB. PERSISTENT LOW LEVEL
THETAE ADVECTION EXISTS. BECAUSE OF ITS PERSISTENCE...IT IS
DIFFICULT TO ASCERTAIN GOOD DETAILS ON EXACTLY WHAT THE CONVECTION
MAY DO AFTER IT FIRES UP THIS EVENING. IN THE NEAR TERM...WOULD NOT
BE SURPRISED TO SEE SOME SCATTERED SHOWERS AND AN ISOLATED
THUNDERSTORM IN OUR SOUTHEASTERN ZONES LATE THIS AFTERNOON AND EARLY
EVENING WHERE CUMULUS HAS DEVELOPED. BUT OVERALL...TRYING TO FIGURE
OUT WHEN THE MORE BONAFIDE CONVECTION WILL DEVELOP AND WHEN IS A
LITTLE MORE CHALLENGING. PER UPPER QG FORCING...THE UPPER WAVE
ACTUALLY STAYS TO THE WEST OF OUR AREA. SO EXAMINING DETAILS LOWER...
700-500MB QG DOES SHOW A SHORT WAVE MOVING ACROSS OUR FORECAST AREA
TONIGHT EXITING TO THE EAST ON SUNDAY MORNING. CONVECTION SHOULD
FIRST FIRE NEAR THE SURFACE TROUGH CLOSE TO THE SHORT WAVE EARLY
THIS EVENING...POSSIBLY IMPACTING SOME OF OUR WESTERN ZONES EARLY
THIS EVENING. IT SHOULD THEN MOVE EAST TO NORTHEAST ALONG THE MID
LEVEL FLOW. A SEVERE POTENTIAL CERTAINLY EXISTS. BUT SEEING THE
AMOUNT OF CLOUD COVER WHICH HELD ON TODAY...ML CAPES ARE LIKELY
OVERDONE A BIT OFF OF THE NAM MODEL. IN ADDITION...NAM SURFACE DEW
POINTS ARE A LITTLE HIGH. WIND WISE...DECENT SHEAR EXISTS IN OUR
WESTERN ZONES THIS EVENING BEFORE WANING IN THAT AREA...WITH THE
SHEAR SHIFTING EASTWARD TOWARD THE I 29 CORRIDOR OVERNIGHT AND LATE
TONIGHT. HAVE SEEN BETTER SHEAR FOR THIS TIME OF YEAR...BUT STRONG
WIND IS CERTAINLY A THREAT WITH ANY QLCS DEVELOPMENT ALONG WITH
BOWING SEGMENTS...AND THE SHEAR IS PERPENDICULAR TO ANTICIPATED
CONVECTIVE MOVEMENT. LARGE HAIL COULD ALSO BE A THREAT IN OUR
WESTERN ZONES THIS EVENING WITH ANY DISCREET CELL DEVELOPMENT. HIGH
POPS ARE CERTAINLY WARRANTED...ESPECIALLY ALONG AND NORTH OF I 90
WITH LESS...SCATTERED TYPE POPS FROM SIOUX CITY IA TO STORM LAKE IA.
BUT THEY COULD SEE SOME DECENT RAIN ALSO...JUST LIKELY NOT AS
WIDESPREAD.
ON SUNDAY...SURFACE WIND FIELDS SHOW THE LIKELIHOOD OF A TROUGH
THROUGH OUR SOUTHWEST ZONES BY AFTERNOON. ACTUALLY PREFER THE
ORIENTATION OF THE GFS AND ECMWF WITH THE PRECIPITATION FIELDS BY
SUNDAY AFTERNOON...WITH A DEVELOPING LINE JUST AHEAD OF THE WIND
SHIFT NEAR THE I 29 CORRIDOR. DEPENDING ON CLOUD COVER DEBRIS...
THIS ACTIVITY COULD ALSO BE SEVERE. FOR MUCH OF THE DAY...AM A BIT
CONCERNED THAT SOME OF OUR POPS COULD BE OVERDONE...ESPECIALLY IN
OUR WESTERN ZONES. BUT WARM AIR ADVECTION DOES PERSIST ALOFT THROUGH
THE DAY.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 320 PM CDT SAT MAY 18 2013
ANY CONVECTION THAT DEVELOPS THROUGH THE CENTRAL PORTIONS OF THE CWA
WILL PUSH OFF TO THE EAST THROUGH THE EVENING...WITH SOME SEVERE
STORMS STILL POSSIBLE DURING THE EVENING BEFORE THE INSTABILITY
WANES LATER IN THE EVENING. THINK THERE WILL BE A GENERAL DECREASE
IN COVERAGE OF CONVECTION LATER AT NIGHT WITH DRYING MIDLEVELS. DO
BEGIN TO SEE THERMAL PROFILES COOL JUST A BIT...WITH LOWS RANGING
FROM THE LOWER 60S EAST TO MID 50S WEST.
MESSY PATTERN CONTINUES THROUGH AT LEAST MIDWEEK AS AN UPPER LEVEL
LOW SPINS OVER THE THE CENTRAL PORTIONS OF THE NATION FOR MONDAY
AND TUESDAY BEFORE PUSHING INTO THE NORTHERN MISSISSIPPI
VALLEY/WESTERN GREAT LAKES REGION ON WEDNESDAY. WITH THIS
FEATURE...WILL HAVE PERIODIC SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE AREA DURING THIS TIME FRAME. OF COURSE HARD TO
PINPOINT CONVECTIVE TIMING/DEVELOPMENT IN THIS KIND OF SET
UP...WITH VARIOUS SHORTWAVES/VORT MAXES ROTATING AROUND THE UPPER
LEVEL LOW THROUGH THE PERIOD. HOWEVER...AT THIS POINT THE BETTER
CHANCE OF PRECIPITATION ON MONDAY LOOKS TO BE OVER THE WEST CLOSER
TO THE PARENT LOW/WIND SHIFT LINE...THEN SHIFTING EASTWARD ON
TUESDAY AND WEDNESDAY AS THE DYNAMICS/BEST LIFT PULLS OFF TO THE
EAST. WOULD NOT REALLY EXPECT MUCH IN THE WAY OF SEVERE STORMS
THROUGH THIS PERIOD WITH AN INCREASINGLY STABLE
ATMOSPHERE...THOUGH AS MENTIONED IN PREVIOUS DISCUSSION CANNOT
RULE BRIEF FUNNEL CLOUDS/SPIN UPS ON MONDAY OR TUESDAY AFTERNOON
WITH THE COLD CORE LOW OVERHEAD...BUT WOULD DEPEND ON
PRECIPITATION TRENDS/BREAKS IN CLOUDS/AND RESULTANT LOW LEVEL
LAPSE RATES ETC. WITH THE LOW OVERHEAD...WILL SEE A GENERAL
COOLING TREND THROUGH MID WEEK...WITH HIGHS TRENDING TOWARD BELOW
NORMAL LEVELS...INTO THE 50S AND 60S FOR TUESDAY AND WEDNESDAY.
FARTHER OUT IN THE EXTENDED...THE UPPER LEVEL LOW CONTINUES TO FILL
AND PULL OFF TO THE EAST FOR THE END OF THE WEEK...WITH UPPER
LEVEL RIDGING INTO THE PLANS STATES FOR THURSDAY THROUGH SATURDAY.
WITH THIS COMES A WARMING TREND...BACK TO NORMAL...AND MOSTLY DRY
CONDITIONS THROUGH THE PERIOD.
&&
.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.
&&
$$
UPDATE...SCHUMACHER
SHORT TERM...MJF
LONG TERM...JM
AVIATION...CHENARD
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 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 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 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 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 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...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 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 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
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 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 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 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 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)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
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
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
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 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 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 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
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 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 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 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