Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/21/14
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
808 PM MDT WED AUG 20 2014
.UPDATE...
ISSUED AT 808 PM MDT WED AUG 20 2014
ISOLATED TO SCATTERED STORMS HAVE FORMED AND ARE MOVING ACROSS
NORTHEAST COLORADO. EXPECT MOST OF THE CONVECTION TO END BY
MIDNIGHT AS THE AIRMASS STABILIZES. OVER THE FAR NORTHEAST
CORNER...A FEW WEAK SHOWERS AND STORMS WILL BE POSSIBLE INTO THE
EARLY MORNING HOURS. ADJUSTED THE FORECAST TO MATCH UP WITH
CURRENT TRENDS.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 158 PM MDT WED AUG 20 2014
MIDLEVEL QUASIGEOSTROPHIC SUBSIDENCE /FROM RAP ANALYSES/ AND
STABILITY /ACARS DATA/ IS KIND OF KEEPING CONVECTION AT BAY AS OF
20Z. THERE ARE A FEW ECHOES ON THE RADAR BUT THEY ARE RATHER WEAK
AND SHORT-LIVED AT THIS TIME. THERE IS ALSO A VERY LOCALIZED AREA
OF DOWNSLOPE FLOW OVER BOULDER COUNTY WHICH HAS LOWERED DEWPOINTS
AND GPS-MEASURED PRECIPITABLE WATER VALUES THERE AND PRETTY MUCH
SQUELCHED THE CONVECTION ALTOGETHER. THE HRRR HAS BEEN A BIT
OVERZEALOUS WITH CONVECTION THAT IS SUPPOSED TO BE ONGOING AT THIS
TIME AND INSISTS ON GENERATING QUITE A BIT OF ACTIVITY INTO THE
EVENING HOURS OF THE PLAINS. THE GFS QPF FIELDS SUGGEST THE SAME
THING WITH THE NAM AND ECMWF SEEMING A BIT MORE IN TOUCH WITH
REALITY. IT SEEMS PRUDENT TO HOLD ONTO LOW POPS IN ALL AREAS THIS
EVENING. TOMORROW DOES NOT APPEAR TO BE MUCH DIFFERENT THAN
TODAY. QUASIGEOSTROPHIC FORECAST DIAGNOSTICS CONTINUE TO FORECAST
SUBSIDENCE AND MODEL SOUNDINGS HAVE THE MIDLEVEL INSTABILITY LIKE
TODAY. CONSEQUENTLY NOT EXPECTING ANY MORE CONVECTION THAT WHAT
IS AROUND TODAY WITH THE PLAINS PERHAPS NOT SEEING ANYTHING.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 PM MDT WED AUG 20 2014
PRETTY GOOD MODEL AGREEMENT THROUGH THIS PERIOD...SHORTWAVES LIFT
OUT OF THE MEAN TROUGH OVER THE WEST PASSING OVER COLORADO ON
FRIDAY AND SUNDAY. A BIT MORE DISCREPANCY BY THE MIDDLE OF NEXT
WEEK WITH THE PROSPECTS FOR THE TROUGH SHIFTING EAST...OR JUST
ANOTHER SHORTWAVE MOVING AROUND IT.
FOR THE FRIDAY WAVE...WE WILL BE FIGHTING THE SAME ISSUES WE HAVE
HAD WITH SEVERAL OF THESE MOISTURE SURGES. WARM ADVECTION ALOFT
WILL LIMIT INSTABILITY WHILE THE LOW LEVELS DO NOT MOISTEN
MUCH...AND BY THE TIME THE BEST LIFT ARRIVES THERE IS EVEN A
LITTLE COOLING AT THE SURFACE. STILL EXPECTING INCREASED SHOWER
COVERAGE BUT MAINLY DUE TO LIFT IN THE ELEVATED MOIST LAYER. THIS
CURRENTLY APPEARS TO BE PLAYED WELL WITH SCATTERED SHOWERS AND
STORMS MAINLY FRIDAY AFTERNOON AND EVENING. I DID ADD A BIT MORE
SHOWER ACTIVITY THURSDAY NIGHT AS SOME MODEL RUNS SHOW SOME
CONVECTION MOVING OFF THE SOUTHERN COLORADO MOUNTAINS AND
PERSISTING OVERNIGHT. ALSO SLOWED DOWN THE END OF THE SHOWERS
EARLY SATURDAY IN LINE WITH MODEL TRENDS.
FOR THE WEEKEND...DRIER AIR SHOULD TAKE AWAY THE INSTABILITY SO
EXPECTING FAIRLY QUIET DAYS...STILL A LITTLE DIURNAL CONVECTION
AND SOME LIFT FROM THE SECOND WAVE SUNDAY SHOULD HELP...BUT A
RATHER UNFAVORABLE ENVIRONMENT.
FOR EARLY NEXT WEEK...THERE APPEARS TO BE A WEAK FRONT DROPPING
DOWN THE PLAINS IN THE MONDAY/TUESDAY TIME PERIOD RELATED TO SOME
DEEPENING OF THE UPSTREAM TROUGH. THIS COULD BRING INCREASED LOW
LEVEL MOISTURE...BUT ALSO SOME LOW LEVEL COOLING. SO ONCE AGAIN A
TRADEOFF THAT RESULTS IN SOME INCREASED COVERAGE...BUT NOT
NECESSARILY A LOT OF RAIN. THERE COULD BE AN OPTIMAL TIME ON
TUESDAY OR WEDNESDAY IF THE TROUGH AXIS DOES SHIFT EASTWARD WHERE
THERE IS A COMBINATION OF LIFT AND INSTABILITY. GFS WOULD SUGGEST
DRYING BEHIND THE TROUGH BY WEDNESDAY...WHILE THE ECMWF HOLDING
THE LONGWAVE TROUGH WEST OF US WOULD INDICATE NO COOLING ALOFT.
SO OVERALL MINOR VARIATIONS ON AN ENVIRONMENT WHICH IS ONLY
SLIGHTLY UNSTABLE IN THE AFTERNOONS...BUT IN THE MOIST PERIODS
COULD ALLOW SOME WEAK CONVECTION WHENEVER THERE IS FORCING. BLEND
OF THE MODEL CONSENSUS WITH THE PREVIOUS FORECAST LOOKS GOOD...I
DID RAISE POPS A LITTLE ON TUESDAY AND WEDNESDAY ON THE PLAINS IN
LINE WITH OUR NEIGHBORING OFFICES...WITH GREATER MOISTURE OUT
THERE THAT SEEMS REASONABLE.
&&
.AVIATION...(FOR THE TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 808 PM MDT WED AUG 20 2014
AN ISOLATED SHOWER OF THUNDERSTORM WILL REMAIN POSSIBLE THROUGH
05Z. WINDS WILL CONTINUE TO VARY DUE TO OUTFLOWS FROM NEAR BY
STORMS. EVENTUALLY WINDS WILL SETTLE AT A NORMAL SOUTHERLY
DIRECTION...LIKELY AROUND 06Z. THERE WILL BE ANOTHER CHANCE FOR
SHORT LIVED THUNDERSTORMS THURSDAY AFTERNOON AND EVENING. OUTFLOWS
FROM THE STORMS WILL LIKELY CAUSE A FEW WIND SHIFTS LATE IN THE
DAY.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MEIER
SHORT TERM...ET
LONG TERM...GIMMESTAD
AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS PUEBLO CO
639 PM MDT WED AUG 20 2014
.UPDATE...
ISSUED AT 636 PM MDT WED AUG 20 2014
UPDATED FORECAST TO ADJUST FOR NR TERM TRENDS. LOOKS LIKE A FEW
ISOLD SHOWERS/TS COULD HANG ON OVER THE MTS AND ERN PLAINS THIS
EVE...BUT TREND IS DOWNWARD AND COVERAGE WILL BE MINIMAL SO HAVE
DROPPED MOST OF THE POPS BELOW 10 PERCENT FOR TONIGHT. ROSE
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 238 PM MDT WED AUG 20 2014
UPR LEVEL LOW IS SITTING ALONG THE SRN CA COAST TODAY AND IS
EXPECTED TO MOVE LITTLE IN THE NEXT 24 HOURS. WV SATELLITE IMAGES
SHOWING DRIER AIR HAS WORKED IT WAY INTO WRN CO TODAY. HRRR AND RAP
SHOWING MAINLY ISOLD PCPN COVERAGE THIS EVENING OVER WESTERN
PORTIONS OF THE FORECAST AREA...WITH ISOLATED TO SCT COVERAGE OVR
THE ERN MTS AND SERN PLAINS. A WEAK BOUNDARY IS FORECAST TO MOVE
INTO THE PALMER DVD AREA EARLY THIS EVENING AND THEN WORK ITS WAY
SOUTH. THIS BOUNDARY MAY HELP KICK OFF ADDITIONAL CONVECTION. THERE
COULD BE A FEW LINGERING SHOWERS OR TSTMS OVR THE SERN PLAINS...BUT
THINK THAT MOST OF THE PCPN SHOULD END BY 06Z.
ON THU...IT DOES NOT LOOK ALL THAT MOIST OVR THE FORECAST AREA.
PRECIPITABLE WATER VALUES OVR WRN AREAS ARE FORECAST TO BE SIMILAR
TO TODAY...WITH DRIER CONDITIONS OVR ERN AREAS. AS A RESULT THE
FORECAST MODELS SHOW MAINLY ISOLD TO SCT POPS OVR THE MTNS IN THE
AFTERNOON HOURS...WITH POSSIBLY A FEW STORMS OVR THE LOWER
ELEVATIONS. HIGH TEMPS FOR THU SHOULD BE AROUND AVERAGE IN THE HIGH
VALLEYS...WITH SLIGHTLY ABOVE NORMAL READINGS OVR THE SERN PLAINS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 238 PM MDT WED AUG 20 2014
NOT MUCH CHANGE TO THE FORECAST THINKING WITH THE GFS COMING INTO
LINE WITH THE ECMWF AND NAM SOLUTIONS. ENSEMBLES ARE STILL
DISPLAYING QUITE A BIT OF SPREAD BY EARLY NEXT WEEK...BUT
CONFIDENCE IS A HIGHER THAN IT WAS YESTERDAY IN A FORECAST
SOLUTION.
AN UPPER LEVEL DISTURBANCE OVER SOUTHERN CALIFORNIA IS FORECAST TO
EJECT NORTHEAST ACROSS COLORADO ON FRIDAY. EXPECT A FEW SHOWERS
AND THUNDERSTORMS TO BE ONGOING THURSDAY EVENING AND DISSIPATING
THROUGH MIDNIGHT OVER THE MOUNTAINS...WITH PERHAPS A FEW LINGERING
SHOWERS OVER THE PALMER DIVIDE INTO NORTHEAST COLORADO INTO EARLY
FRIDAY MORNING.
FRIDAY HAS THE POTENTIAL TO BE INTERESTING. THE UPPER DISTURBANCE
OVER ARIZONA WILL EJECT ACROSS COLORADO THROUGH FRIDAY EVENING.
MODELS QUICK TO ADVECT MOISTURE NORTH ACROSS COLORADO...AND SHEAR
LOOKS TO INCREASE TO AROUND 30 KTS OR SO BY THE AFTERNOON WITH
MODEST INSTABILITY. EXPECT SHOWER AND THUNDERSTORM DEVELOPMENT BY
MID MORNING FRIDAY ALONG THE CONTINENTAL DIVIDE...AND SPREADING
EAST INTO THE I-25 CORRIDOR BY EARLY IN THE AFTERNOON. MODEL QPF
FIELDS ARE INDICATING THAT HEAVY RAINFALL WILL BE
POSSIBLE...ESPECIALLY OVER THE MOUNTAINS AND LOCATIONS OVER THE
PALMER DIVIDE. FLASH FLOODING WILL BE POSSIBLE ON AREA BURN SCARS
AND FLOOD PRONE AREAS FRIDAY AFTERNOON AND EVENING. SOME STORMS
ACROSS THE PLAINS COULD BECOME STRONG...WITH SMALL HAIL AND GUSTY
OUTFLOW WINDS ALSO POSSIBLE. MODELS IN GOOD AGREEMENT WITH
THUNDERSTORMS SHIFTING EAST ACROSS THE PLAINS FRIDAY NIGHT WITH
ALL ACTIVITY EXITING INTO KANSAS BY SATURDAY MORNING.
SATURDAY WILL LIKELY BE A PRETTY QUIET DAY ACROSS SOUTHERN
COLORADO GIVEN SUBSIDENCE BEHIND THE DEPARTING UPPER SYSTEM. A
COUPLE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL
REMAIN POSSIBLE OVER THE MOUNTAINS...BUT COVERAGE LOOKS TO BE
MINIMAL.
A BROAD TROUGH WILL PERSIST OVER THE WESTERN CONUS THROUGH THE
MIDDLE OF NEXT WEEK WITH A COUPLE OF MORE DISTURBANCES MOVING
ACROSS SOUTHERN COLORADO. THE NEXT ONE LOOKS TO MOVE ACROSS THE
REGION ON SUNDAY. THIS WILL BRING ANOTHER UPTICK IN SHOWER AND
THUNDERSTORM ACTIVITY ACROSS THE STATE...WITH ACTIVITY STARTING
OVER THE MOUNTAINS LATE SUNDAY MORNING AND SPREADING EAST THROUGH
THE AFTERNOON AND EVENING. IN ADDITION...A COLD FRONT WILL MOVE
SOUTH ACROSS THE PLAINS DURING THE AFTERNOON...TURNING LOW LEVEL
FLOW UPSLOPE...WHICH WILL LIKELY AID PRECIPITATION DEVELOPMENT
ACROSS THE PLAINS SUNDAY AFTERNOON AND EVENING.
MODELS A BIT DIFFERENT ON THE ARRIVAL OF THE NEXT DISTURBANCE
DROPPING ACROSS THE ROCKIES...WITH GFS HAS BEEN BRINGING IT
THROUGH MONDAY EVENING...WITH THE ECMWF IS A BIT SLOWER ON
TUESDAY. THIS WILL LIKELY LEAD TO ANOTHER ROUND OF DECENT
PRECIPITATION FOR THE MOUNTAINS...AND SPREADING EAST INTO THE
PLAINS SOMETIME IN THE MONDAY TO TUESDAY TIME FRAME. THIS SYSTEM
LOOKS TO BE ACCOMPANIED BY A STRONG COLD FRONT WHICH SHOULD HELP
THE PLAINS SEE ANOTHER SHOT FOR PRECIPITATION. MOZLEY
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 238 PM MDT WED AUG 20 2014
VFR CONDITIONS ARE EXPECTED AT KCOS...KPUB AND KALS TONIGHT THROUGH
THURSDAY AFTERNOON. SOME THUNDERSTORMS WILL BE POSSIBLE IN THE
VCNTY OF KCOS EARLY THIS EVENING...BUT MAY NOT MAKE IT INTO THE
VCNTY OF KPUB AND KALS. THE MAIN THREATS WITH TSTMS WILL BE GUSTY
WINDS. ON THURSDAY AFTERNOON SOME TSTMS ARE EXPECTED OVR THE HYR
TRRN AND ONE OR TWO COULD MAKE IT INTO THE VCNTY OF KCOS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ROSE
SHORT TERM...28
LONG TERM...MOZLEY
AVIATION...28
AREA FORECAST DISCUSSION
NWS PUEBLO CO
320 PM MDT TUE AUG 19 2014
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 249 PM MDT TUE AUG 19 2014
WV SATELLITE IMAGERY TODAY SHOWING THE MONSOON MSTR PLUME OVR
UT...BUT SLOWLY SHIFTING EASTWARD AS AN UPR LOW MOVES SOUTHWARD
ALONG THE CA COAST. SCATTERED SHOWERS AND TSTMS ARE EXPECTED THIS
EVENING OVR THE MTNS AND UPR ARKANSAS RIVER VALLEYS...WITH ISOLD
ACTIVITY OVR THE SERN PLAINS. BY 03Z THE HRRR AND RAP SHOW LITTLE IF
ANY PCPN OVR THE SERN PLAINS...WITH JUST SOME ISOLD PCPN OVR THE MTN
AREAS. OVERNIGHT THAT UPR LOW WL MOVE OVR SRN CA AND THE MONSOON
PLUME SHIFTS INTO WRN CO. AS A WX DISTURBANCE THE MSTR LIFTS
NORTHEASTWARD ACRS NWRN CO...SOME PCPN WL PROBABLY CONTINUE THRU THE
NIGHT ALONG THE CONTDVD...ESPECIALLY OVR THE CENTRAL CO MTNS WHICH
WL BE CLOSEST TO THE DISTURBANCE AND BETTER MSTR.
ON WED THE UPR LOW IS EXPECTED TO REMAIN OVR SRN CA. THE BEST MSTR
GOES NORTH OF THE AREA WITH THAT DISTURBANCE...AND MODELS ARE MAINLY
SHOWING SPOTTY PCPN FOR THE FORECAST AREA. WILL KEEP SCT POPS OVR
THE MTNS AREAS FOR WED AFTERNOON AND ISOLD POPS OVR THE SAN LUIS
VALLEY AND I-25 CORRIDOR. HIGH TEMPS ON WED SHOULD GENERALLY BE
AROUND TO A LITTLE ABOVE AVERAGE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 249 PM MDT TUE AUG 19 2014
THE UPPER LEVEL PATTERN IS FORECAST TO FEATURE A BROAD UPPER LEVEL
TROUGH OVER THE NORTHWEST TO NORTH-CENTRAL CONUS AND A HIGH
PRESSURE CENTER OVER THE SOUTHEAST STATES. THIS WILL PUT SOUTHERN
COLORADO UNDER SOUTHWESTERLY FLOW FOR MUCH OF THE EXTENDED. THERE
ARE MODEL DIFFERENCES IN HOW THEY WANT TO HANDLE UPPER LEVEL
DISTURBANCES IN THE FLOW...AND ENSEMBLES DEVELOP HIGH SPREADS BY
THIS WEEKEND LEADING TO LOWER CONFIDENCE IN THE LAST COUPLE OF
DAYS OF THE EXTENDED PERIOD.
THE GFS HAS REMAINED CONSISTENT FROM RUN TO RUN WITH AN UPPER
LEVEL LOW OVER SOUTHERN CALIFORNIA AND EJECTING IT NORTHEAST
ACROSS COLORADO ON THURSDAY NIGHT INTO FRIDAY. THE LATEST ECMWF IS
MORE IN LINE WITH THIS SOLUTION...HOWEVER IS ABOUT 24 HOURS SLOWER
IN EJECTING THE SYSTEM OUT. THE BIGGEST FORECAST CHANGE FOR THE
GFS IS WHERE THE SYSTEM DEVELOPS CONVECTION ON THURSDAY.
EXPECT ONGOING CONVECTION ACROSS THE MOUNTAINS WEDNESDAY EVENING
WITH MODELS BRINGING BAND EAST ACROSS THE PLAINS THROUGH THE
OVERNIGHT HOURS AS A WEAK DISTURBANCE LIFTS NORTHEAST. BY THURSDAY
MORNING...THE LOW PRESSURE CENTER OVER SOUTHERN CALIFORNIA IS
FORECAST TO OPEN UP AND LIFT NORTHEAST ACROSS COLORADO.
THUNDERSTORMS ARE FORECAST TO DEVELOP OVER THE MOUNTAINS BY LATE
THURSDAY MORNING. THUNDERSTORMS DEVELOPMENT IS THEN EXPECTED
EASTWARD ACROSS THE PALMER DIVIDE THROUGH THE AFTERNOON AND
EVENING HOURS. THE PREVIOUS RUN OF THE GFS HAD THIS THUNDERSTORM
DEVELOPMENT FURTHER SOUTH OVER SOUTHERN COLORADO...SO WHERE THIS
DISTURBANCE EJECTS WILL PLAY A ROLE IN WHAT AREAS SEEN THE
POTENTIAL FOR HEAVIER PRECIPITATION. THE ECMWF AND NAM SOLUTIONS
ARE A BIT SLOWER WITH THIS SYSTEM...WITH IT EJECTING ACROSS
SOUTHERN COLORADO ON FRIDAY AFTERNOON. IF THIS IS THE
CASE...THURSDAYS CONVECTION WILL LIKELY REMAIN TIED TO THE TERRAIN
AND PALMER DIVIDE...WITH NOT MUCH EXPECTED ON THE PLAINS. THE
HEAVY PRECIPITATION CHANCES WOULD THEN FOCUS ON FRIDAY AFTERNOON
AND NIGHT...WITH HEAVY RAINFALL AND THE POTENTIAL FOR FLASH
FLOODING. THE IMPORTANT THING TO REMEMBER...IS THAT SOME TIME
BETWEEN THURSDAY AND FRIDAY NIGHT...SOUTHERN COLORADO WILL LIKELY
SEE A PERIOD OF WIDESPREAD HEAVIER RAINFALL.
A BROAD TOUGH IS FORECAST TO REMAIN ENTRENCHED ACROSS THE PACIFIC
NORTHWEST INTO THE NORTHERN PLAINS SATURDAY THROUGH TUESDAY. THE
MAIN FORECAST ISSUE WILL BE HOW DEEP THE TROUGH GETS. THE GFS
SOLUTIONS DIGS IT THE FURTHEST SOUTH...WITH CONTINUED ACTIVE
WEATHER ACROSS THE AREA...WHILE THE ECMWF IS KEEP MOST OF THE
ENERGY CONFINED TO OUR NORTH WITH LESS CHANCES FOR PRECIPITATION.
A COLD FRONT IS FORECAST TO DROP SOUTH ACROSS THE PLAINS ON SUNDAY
WHICH MAY BE THE BEST OPPORTUNITY FOR WIDESPREAD PRECIPITATION
ACROSS THE AREA. OTHERWISE...CONVECTION WILL LIKELY REMAIN OVER
THE MOUNTAINS WITH LIMITED ACTIVITY OVER THE PLAINS. MOZLEY
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 249 PM MDT TUE AUG 19 2014
VFR CONDITIONS ARE EXPECTED THIS EVENING THROUGH WEDNESDAY AFTERNOON
AT KCOS...KPUB AND KALS. SOME TSTMS MAY MOVE INTO THE VCNTY OF THE
TERMINAL SITES THIS EVENING...AND THEN AGAIN ON WED AFTERNOON. THE
MAIN THREATS WITH TSTMS WILL BE GUSTY WINDS AND LIGHTNING...BUT SOME
LOCALLY HEAVY RAIN IS ALSO POSSIBLE.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...MOZLEY
AVIATION...28
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1129 PM MDT MON AUG 18 2014
.UPDATE...
ISSUED AT 820 PM MDT MON AUG 18 2014
UPDATED MOST POP FORECASTS, REMOVING POPS OVER THE PLAINS AND
EASTERN MOUNTAINS, WHILE ADDING/EXTENDING PRECIP CHANCES OVER THE
SOUTHWEST MOUNTAINS AND SAN LUIS VALLEY...AS AREA OF TSRA OVER THE
SAN JUANS WILL MOVE EAST ACROSS LOWER ELEVATIONS BEFORE ENDING.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 259 PM MDT MON AUG 18 2014
THE UPR RIDGE IS STILL CENTERED NR THE FOUR CORNERS AREA TODAY
AND PRECIPITABLE WATER VALUES ARE SIMILAR TO WHAT THEY WERE
YESTERDAY. ISOLATED SHOWERS AND TSTMS HAVE DEVELOPED OVR SOME OF
THE MOUNTAIN AREAS AS OF 1930Z. SHOULD SEE COVERAGE OVR THE MTNS
INCREASE THIS AFTERNOON. HRRR AND RAP SHOW PCPN DEVELOPING/MOVING
OVR THE SERN PLAINS AND PORTIONS OF THE SAN LUIS VALLEY LATER THIS
AFTERNOON AND THIS EVENING. THE HRRR AND RAP HAVE PCPN ENDING IN
MOST LOCATIONS BY LATE EVENING...BUT SHOW THE POTENTIAL FOR SOME
CONTINUING OVR THE SAN JUAN MTNS INTO THE LATE NIGHT HOURS.
AS AN UPR TROF DIGS INTO SRN CA TONIGHT AND TUESDAY...THE UPR RIDGE
OVR OUR AREA SHIFTS EASTWARD. THIS PUSHES A LITTLE BETTER MSTR INTO
WRN CO FOR TUE...WITH PRECIPITABLE WATER VALUES INCREASING SLIGHTLY
OVR THE CONTDVD. AS A RESULT THERE SHOULD BE MORE WIDESPREAD SHOWER
AND TSTM ACTIVITY ALONG THE CONTDVD TOMORROW. THE ERN MTNS WL
LIKELY SEE SCT PCPN DEVELOPING IN THE AFTERNOON HOURS...WHILE THE
SERN PLAINS SHOULD JUST SEE A FEW SHOWERS OR STORMS DEVELOP. HIGH
TEMPS ON TUE SHOULD BE 5-8 DEGREES ABOVE AVERAGE OVR THE SERN
PLAINS...AND AROUND NORMAL IN THE SAN LUIS VALLEY AND UPR ARKANSAS
RIVER VALLEY.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 259 PM MDT MON AUG 18 2014
...ACTIVE WEATHER FOR AT LEAST THE NEXT WEEK...
MODELS ARE NOW IN REASONABLE AGREEMENT THAT THE CUTOFF LOW
OFF THE CA COAST WILL PHASE WITH THE TROUGH MOVING INTO THE
PACNW...AND THIS WILL LEAD TO AN ENHANCED MONSOONAL PATTERN
FOR THE LATTER PART OF THIS WEEK AND BEYOND. A COUPLE OF
ADDITIONAL SHORTWAVES WILL MOVE THROUGH THE LONGWAVE TROUGH
PATTERN THAT IS OVER WRN CANADA...BRINGING THE THREAT FOR PERIODS
OF HEAVY RAIN TO OUR AREA.
TUE NIGHT...EXPECT ISOLD STORMS TO PERSIST OVER THE CONTDVD
AS THE PLUME BEGINS TO MOVE OVR WRN CO. BY LATE WED THE TROUGH
AND ABSORBED CUTOFF WILL MOVE INTO NW AZ/SW UT...AND THE THREAT
OF HEAVY BANDS OF CONVECTION WILL CONTINUE FOR THE SW MTS AND
CONTDVD. DEPENDING ON WHAT HAS ALREADY FALLEN OVR THE MTS
WE COULD SEE THE THREAT OF MORE FLASH FLOODING AND RISK OF
SLIDES FOR THE MT AREAS. TIMING FOR OUR CWA`S STAGES IN THE
PRO CYCLING CHALLENGE DOES NOT LOOK FAVORABLE AS THE STRONGEST
DYNAMICS FROM THIS SYSTEM MOVE THROUGH ON THURSDAY. THAT IS WHEN
THE CORE OF A 100 KT JET STREAK MOVES THROUGH CO. THIS IS PRETTY
ROBUST FOR AN AUGUST SYSTEM. WITH H6 TEMPS AT MINUS 2C OR LOWER IN
THE CORE OF THE LOW...COULD EASILY SEE SOME SNOW FOR ELEVS ABOVE
12K FEET BY FRI MORNING. THE GFS BRINGS US A BIT OF A BREAK IN THE
ACTION ON SATURDAY BEFORE ANOTHER FRONT COMES THROUGH SAT
NIGHT...FOLLOWED BY A THIRD SYSTEM SUN OR MON. THE ECMWF HAS SOME
OF THE HEAVIEST QPF ON FRI AND CONTINUES THE ONSLAUGHT THROUGH THE
WEEKEND. A BIT HARD TO SAY WHEN THE HEAVIEST RAIN WILL FALL...BUT
THE THREAT OF HEAVY PRECIP WILL CERTAINLY BE WITH US SO LONG AS
THIS PARADE OF SHORTWAVES CONTINUE...AT LEAST THROUGH THE FIRST
DAYS OF NEXT WEEK. ENSEMBLE POPS LOOKED MUCH TOO LOW SO HAVE
RAISED POPS BY AT LEAST 10 PERCENT OVER THIS TIME FRAME FOR BOTH
THE PLAINS AND MTS...WHILE THE MTS WILL SEE THE BEST SHOT AT HEAVY
PRECIP. TEMPS WILL TREND DOWNWARD THROUGH THE PERIOD...STARTING IN
THE NR 90 RANGE FOR TUE-THU...AND THEN FALLING INTO THE 80S AND
POSSIBLY LOWER FOR THE PLAINS NEXT WEEKEND. LOOKS LIKE THE
FORECAST WILL REMAIN CHALLENGING FOR THE REST OF THIS MONTH. ROSE
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1125 PM MDT MON AUG 18 2014
STILL SOME VERY ISOLATED TSRA LINGERING OVER THE SANGRES AND SAN
JUANS AS OF 0530Z...EXPECT THESE TO END BY 08Z WITH VFR CONDITIONS
ACROSS THE AREA...INCLUDING THE TAF SITES...FOR THE REMAINDER OF
THE NIGHT. ON TUESDAY...MOISTURE INCREASES ACROSS WESTERN COLORADO
AND EXPECT TSRA TO BE MORE NUMEROUS OVER THE HIGHER TERRAIN IN THE
AFTERNOON. HAVE INCLUDED A VCTS MENTION AT BOTH KALS AND KCOS FOR
LATE AFTERNOON INTO THE EVENING...THOUGH STORMS WILL BE FAIRLY
HIGH BASED WITH ONLY BRIEF MVFR CONDITIONS UNDER THE STRONGEST
CELLS. TSRA LESS LIKELY AT KPUB...THOUGH GUSTY OUTFLOW WINDS
CERTAINLY POSSIBLE...ESPECIALLY 22Z-02Z PERIOD.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PETERSEN
SHORT TERM...28
LONG TERM...ROSE
AVIATION...PETERSEN
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1102 PM MDT MON AUG 18 2014
.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 333 PM MDT MON AUG 18 2014
BIG CHANGES WILL OCCUR OVER THE NEXT 24 HOURS AS AN UNSEASONABLY
STRONG AND NEARLY VERTICALLY STACKED TROUGH...CURRENTLY OVER
CALIFORNIA...MOVES EAST INTO THE GREAT BASIN. THIS BRINGS EASTERN
UTAH AND WESTERN COLORADO INTO IDEAL POSITION FOR DEEP
SUBTROPICAL MOISTURE TO ADVECT INTO THE REGION. PRECIPITABLE
WATER VALUES OF 1 TO 1.3 INCH ARE EXPECTED TO COVER EASTERN UTAH
AND EVEN EXTREME WESTERN COLORADO BY LATE TUESDAY AFTERNOON. THIS
IS ALMOST 2 STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF
YEAR.
MODELS ARE FORECASTING MULTIPLE VORT MAXES TO REACH THE UT/CO
BORDER THROUGHOUT THE DAY FROM NOON TO MIDNIGHT. THERE IS SOME
UNCERTAINTY ON THE TIMING OF H3 JET SUPPORT OF 60KTS REACHING THE
AREA...WHICH WILL HELP TO PROVIDE ASCENT IN THE UNIMPRESSIVE CAPE
AND SHEAR ENVIRONMENT. EXPECTING CLOUD COVER TO HINDER INSTABILITY
DURING THE DAY...HOWEVER THIS SCENARIO COULD CHANGE IF SUFFICIENT
CLEAR AIR IS ABOUND BY LATE MORNING. THE RAP SHOWS JET SUPPORT
INCHING INTO EASTERN UTAH AND SOUTHWEST COLORADO DURING THE
MORNING ON TUESDAY...HOWEVER THE NAM AND GFS SHOW THE BEST JET
SUPPORT ON TUESDAY NIGHT AND WEDNESDAY MORNING. STORM MOTION WILL
BE DECENT FOR TUESDAY - ABOUT 20 TO 30 KTS...SO COULD NOT JUSTIFY
A FLASH FLOOD WATCH AT THIS TIME. IT WILL RAIN IN MANY LOCATIONS
BY TUESDAY NIGHT...BUT ONLY EXPECTING MODERATE TO HEAVY RAIN
MULTICELLULAR STORMS CAUSING NUISANCE/SMALL STREAM FLOODING AT
THIS TIME. SEE HYDRO SECTION FOR MORE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 333 PM MDT MON AUG 18 2014
THE FORECAST AREA REMAINS UNDER SW FLOW WED-THU WITH THE JET AXIS
OVERHEAD. MONSOONAL MOISTURE PLUME WEAKENS WITH PRECIPITABLE WATER
VALUES DROPPING UNDER 1 INCH. NAM/GFS SHOW A WEAK 300 MB JET MAX
ARRIVING ON WED FOR POTENTIAL SUPPORT AND INCREASED VERTICAL
SHEAR....AND SHOULD IT ENTRAIN SOME DRIER MIDLEVEL AIR OVER HIGHER
MOISTURE NEAR THE SURFACE...IT COULD LEAD TO SOME STRONGER STORMS
WED AFTERNOON.
MODELS STILL HAVING TROUBLE HANDLING THE UPPER LOW THAT IS
CURRENTLY DROPPING SOUTH ALONG THE NRN CA COAST...WHICH LOWERS
FORECAST CONFIDENCE AFTER MIDWEEK. BUT AT LEAST THE GFS AND ECWMF
NOW BOTH BRING THE 500 MB LOW INLAND...JUST TIMING AND TRACK ARE
DIFFERENT. THE 12Z GFS SWINGS THE LOW INLAND ACROSS SRN CA WED AND
THEN LIFTS IT NE ACROSS UT AS AN OPEN WAVE ON THU. THIS COULD ADD
SOME DYNAMIC PUNCH TO STORM DEVELOPMENT ON THU. THE 12Z ECMWF IS
SLOWER BRINGING IT INLAND AND TRACKS IT FARTHER SOUTH ACROSS AZ
AND NWRN NM. THE 12Z CANADIAN HAS IT SHEARING OUT ALONG THE SRN CA
COAST THU-FRI. MODELS ALSO SHOW ENERGY DROPPING OUT OF THE GULF OF
AK LATE IN THE WEEK THAT SHOULD MAINTAIN TROUGHING OVER THE PAC
NW/NRN ROCKIES.
FOR NOW...WITH FOLLOW THE CONSENSUS MODEL TREND...WHICH SHOWS A
LESSENING OF STORM COVERAGE THE LAST HALF OF THE WEEK BUT NOT A
COMPLETE CESSATION. LOWER LEVEL MOISTURE LIKELY TO LINGER WITH SOME
SMALLER EMBEDDED WAVES IN THE FLOW THAT COULD TRIGGER ISOLATED-
SCATTERED ACTIVITY ABOUT EACH DAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1057 PM MDT MON AUG 18 2014
PLENTY OF CONVECTION CONTINUES THIS MORNING WITH SHOWERS AND OCCNL
RUMBLES OF THUNDER. THIS WILL LIKELY CONTINUE THROUGH 09Z WITH A
SLIGHT DOWNTICK AFTER THAT. SHOWERS AND STORMS WILL PICK UP AGAIN
WITH HEAVY RAIN...HAIL...AND GUSTY OUTFLOW WINDS OVERSPREADING THE
AREA FROM NOON ONWARDS WITH WIDEST COVERAGE FROM 21Z ONWARDS.
IFR/MVFR MAY OCCUR OVER AERODROMES DUE TO HEAVIER SHOWERS DROPPING
VIS AND ALSO DROPPING CIGS. MODELS CONTINUE PRECIP OVERNIGHT SO
EXPECT THESE CONDITIONS TO PERSIST THROUGH 06Z TOMORROW. MTN
OBSCURATIONS WILL ALSO BE COMMON.
&&
.HYDROLOGY...
ISSUED AT 333 PM MDT MON AUG 18 2014
MONSOONAL MOISTURE WILL RETURN TOMORROW AS AN UPPER LEVEL LOW OVER
CALIFORNIA PULLS DEEP SUBTROPICAL MOISTURE INTO THE REGION.
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE FROM WEST TO
EAST THROUGHOUT THE AFTERNOON AND PEAK DURING THE LATE HOURS OF
THE DAY AND OVERNIGHT INTO WEDNESDAY MORNING. EXPECTING TO HAVE
SMALL STREAM AND ARROYO FLOOD ISSUES BY WEDNESDAY MORNING IN THE
USUAL PROBLEM AREAS...BUT AT THIS NOT EXPECTING HIGH COVERAGE OF
TORRENTIAL DOWNPOURS DUE TO THUNDERSTORMS. THEREFORE...NO WATCHES
HAVE BEEN ISSUED AT THIS TIME.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...JAM
LONG TERM...JAD
AVIATION...TGR
HYDROLOGY...JAM
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1000 PM EDT WED AUG 20 2014
.SYNOPSIS...
WET WEATHER LIKELY IMPACTING WESTERN AND CENTRAL PORTIONS OF NEW
ENGLAND BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. DRIER AND
COOLER WEATHER FOLLOWS INTO THE WEEKEND. A WARM-UP IS POSSIBLE
INTO NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL
BOUNDARY SWEEPING SOUTH OUT OF CANADA.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
10 PM UPDATE...
METEOROLOGICAL SQUEEZE PLAY GOING ON THIS EVENING AS WARM FRONT
CONTINUES TO MOVE E SLOWLY FROM NY/PA. AS WELL A TROF OF LOW PRES
CONTINUES TO DEEPEN OFFSHORE. WHILE THE FORMER FEATURE IS MOISTURE
STARVED AND STRUGGLES TO ALLOW ANY PRECIP TO MOVE IN UNDER
INVERTED RIDGING...THE LATTER WILL HAVE TO BE WATCHED. MODELS
CONTINUE TO INDICATE THAT A WEAK INVERTED TROF DEVELOPS...HANGING
BACK TOWARD MVY AND ACK EARLY IN THE MORNING. EVEN THE MESO-SCALE
GUIDANCE INDICATES WEAK CONVERGENCE IN THE FLOW PATTERN. THE
QUESTION IS WHETHER A BAND OF SHOWERS DEVELOPS FAR ENOUGH N TO
EFFECT THE CAPE AND ISLANDS. EARLIER GUIDANCE WAS MUCH MORE ROBUST
WITH THIS AND HAVE SINCE BACKED OFF. AS SUCH...WILL LOWER GUIDANCE
MAINLY TO SLIGHT CHANCE ACROSS THE AREA WITH CHANCE JUST OFFSHORE.
WILL CONTINUE TO MONITOR AS THE EVENING PROGRESSES. DO ALREADY
NOTE SOME LOW CLOUDS DEVELOPING OVER ACK WITH LATEST OB.
PREVIOUS DISCUSSION...
PREVIOUS DISCUSSION...
HEIGHTS FALL AS THE GREAT LAKES LOW SHIFTS INTO THE NE CONUS...
TROUGHING TOWARDS THE W-E AXIS OF LOW PRESSURE AND INSTABILITY OFF
THE MID-ATLANTIC. LABRADOR RIDGE OF HIGH PRESSURE ALONG WITH DRY
AIR AND SUBSIDENCE WILL PERSIST INTO NEW ENGLAND...AHEAD OF WHICH
THE COLLISION TOWARDS LOW PRESSURE AND HIGHER THETA-E AIR WILL
RESULT IN A DEFINED AREA OF CONVERGENCE ACROSS PA/NY...AND
POSSIBLY SE MA.
TO THE W...INCREASING THETA-E MOISTURE LOADING THE MID- TO UPPER-
LEVELS WILL LIKELY RESULT IN INCREASING AND THICKENING CLOUDS W TO
E. BUT STILL A LOT OF DRY AIR TO OVERCOME BELOW H6-7 ESPECIALLY OVER
E NEW ENGLAND WITH THE INVERTED RIDGE. NOTING THE WARM FRONT WELL W
ACROSS PA/NY ALONG WITH PARENT DYNAMICS AND LOW-LEVEL CONVERGENCE...
BEST CHANCES FOR SHOWERS WITHIN AREAS OF DEEP-LAYER ASCENT SHOULD
BE NO FURTHER E OF THE CT-RIVER VALLEY. EXPECTING SPRINKLES. ITS
LIKELY BETTER ACTIVITY WILL BE WELL N/W PARENT WITH BETTER MOISTURE
CONVERGENT ALONG THE NOSE OF THE H925-85 JET INTO THE ADIRONDACKS
ON UP INTO ONTARIO/QUEBEC AS DESTABILIZATION CONCLUDES. PREFER
CHANCE POPS ONLY INTO THE CT-VALLEY.
TO THE SE...TROUGHING SE BACKS LOW PRESSURE AND HIGHER THETA-E AIR
OFF THE E-W STALLED FRONT OFF THE MID-ATLANTIC. THE CONVERGENCE OF
AIR MASSES ALONG AN INVERTED-TROUGH TO THE AFOREMENTIONED LOW WILL
BE THE FOCUS FOR POTENTIAL HEAVY RAIN...EVEN THUNDERSTORMS. MAINLY A
WARM-RAIN PROCESS WITH PWATS UP TO 1.75 INCHES. WHILE A CONSISTENT
SIGNAL AMONG FORECAST SOLUTIONS...OUTCOMES VARY SLIGHTLY LIKELY DUE
TO THE STRENGTH OF INVERTED-RIDGE. WILL GO WITH LIKELY POPS FOR
NANTUCKET WITH CHANCE POPS INTO THE CAPE AND SE MA. THE SETUP IS
ALREADY COMING TOGETHER SEEN PER IR/VISIBLE SATELLITE...BUT A LOT
OF UNCERTAINTY BETWEEN THE STRENGTH OF THE RIDGE AND THE ZONE
SETUP OF CONVERGENCE. WRF/NAM THE MOST ROBUST WITH OUTCOMES. 17Z
HRRR/18Z RAP HAS ACTIVITY MISSING NANTUCKET. NOT ENOUGH CONFIDENCE
TO GO HIGH CATEGORICAL POPS.
THICKER CLOUDS ACROSS THE REGION WILL LIMIT RADIATIONAL COOLING.
ANTICIPATING A MORE MILD NIGHT OVER MUCH OF THE REGION WITH LOWS
AROUND THE UPPER-50S. COOLEST CONDITIONS EXPECTED ACROSS E/SE MA
UNDER LIGHT AND VARIABLE WINDS AND THE BETTER CHANCE OF RADIATING
OUT...LOWS AROUND THE MID-50S. FOR SUCH AREAS THERE IS ALSO THE
POSSIBILITY OF PATCHY GROUND FOG.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
THURSDAY INTO THURSDAY NIGHT...
CLOSED LOW OUT OF THE GREAT LAKES GRADUALLY WOBBLES INTO NEW ENGLAND
THROUGH THE FORECAST PERIOD. THE SYSTEM WEAKENS AS IT TRANSITIONS SW
RE-EMERGING ALONG THE W-E FRONTAL BOUNDARY OFF THE MID-ATLANTIC
TOWARDS THE BETTER THERMAL-INSTABILITY AXIS.
SUBSEQUENT RISING HEIGHTS ALLOWS RIDGING TO BUILD SW THURSDAY
NIGHT. WHILE HIGHER THETA-E AIR STREAMS ACROSS THE REGION WITHIN
THE MID-LEVELS...E-FLOW WITHIN LOW-LEVELS FROM THE LABRADOR HIGH
UNDERCUTS MOISTURE LOADING ALOFT KEEPING CONDITIONS FAIRLY STABLE
AND DRY...LIKELY TO ERODE ACTIVITY S AND W.
AS THE LOW TRANSITIONS AND WEAKENS...PRECIPITATION ACROSS THE CAPE
AND ISLANDS CONCLUDES WITH THE STRENGTHENING INFLUENCE OF THE
RIDGE. ENERGY AND MOISTURE PARENT TO THE LOW IS ANTICIPATED TO
SWEEP MAINLY ACROSS SW NEW ENGLAND...PERHAPS SW OF A LINE FROM
BOSTON TO KEENE NH. WILL KEEP THESE AREAS UNDER CHANCE POPS
ACCORDINGLY WITH ASCENT AND LIKELY CONVERGENCE AGAINST THE SW
BUILDING RIDGE.
WITH THE UNDERCUTTING DRY AND STABLE AIRMASS OFF THE OCEAN WITH THE
STRENGTHENING RIDGE LATE...AND CLOUDS THROUGH THE PERIOD LIMITING
DESTABILIZATION...NOT EXPECTING ANY THUNDER. HIGHS AROUND THE MID-
TO UPPER-70S DURING THE DAY WITH LOWS AROUND THE UPPER-50S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
HIGHLIGHTS...
* QUIET WEATHER EXPECTED THROUGH MUCH OF THE LONG TERM
* UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING
FRONT.
MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. A
PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE
ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL
RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN U.S. THE UPPER
TROUGH IS RATHER PERSISTENT THOUGH AND EACH MODEL RUN KEEPS THE
TROUGH JUST OFFSHORE LONGER AND LONGER.
COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN
QUEBEC WILL KEEP THINGS RELATIVELY DRY. MODELS ARE INDICATING SOME
POTENTIAL FOR QPF EACH DAY THROUGH THE WEEKEND BUT GIVEN THE LACK OF
ANY FORCING MECHANISM AND VERY LITTLE MOISTURE TO SPEAK OF...
THINKING THIS COULD BE CONVECTIVE FEEDBACK RATHER THAN A DEPICTION
OF ANYTHING LIKELY TO OCCUR.
THE HIGH WILL SINK SOUTH THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...EVENTUALLY DROPPING SOUTH AND EAST OF SOUTHERN NEW ENGLAND
AND RETURNING US TO A MORE WESTERLY FLOW. LOW PRESSURE IN ONTARIO
MAY EVENTUALLY MOVE EASTWARD INTO QUEBEC BRINGING A COLD FRONT
THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE
MODELS START TO DIVERGE A BIT WITH THE ECMWF A BIT QUICKER THAN THE
GFS WITH THE APPROACH OF THE FRONT. DEPENDING ON AVAILABLE MOISTURE
THIS MAY INITIATE A FEW SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE.
VFR. LIGHT/VRB WINDS OVERNIGHT BEFORE PREVAILING E/SE THURSDAY
INTO THURSDAY NIGHT. LOW-END VFR CIGS SLOWLY BUILDING E ALONG WITH
-RA CHANCES TOWARDS IJD-ORH-AFN. WILL ALSO NEED TO WATCH SE MA FOR
POTENTIAL +RA AND MVFR-IFR IMPACTS BEGINNING AFTER MIDNIGHT INTO
THU MORNING. CONDITIONS BEGIN TO IMPROVE CLOSER TO FRIDAY
MORNING.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. E/SE FLOW PREVAILS. EXPECT
CONDITIONS NO LOWER THAN LOW-END VFR CIGS. -RA CHANCES MINIMAL.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. -RA CHANCES BEGIN TOWARDS
THURSDAY MORNING ALONG WITH LOW-END VFR CIGS. MVFR CIGS POSSIBLE
THOUGH LOW-CONFIDENCE AT THIS TIME.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF PATCHY
MVFR/IFR FOG EACH NIGHT.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT-TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE.
CLOSELY MONITORING THE SE WATERS. MAY SEE A SURGANCE OF RAIN ALONG
WITH VISIBILITY IMPACTS DURING THE OVERNIGHT HOURS INTO THURSDAY
ALONG WITH AN INCREASE IN E-NE FLOW AS AN AREA OF LOW PRESSURE
DEVELOPS WELL OUT TO SEA. QUITE POSSIBLE WIND GUST UP TO 25
KTS...BUT WILL HOLD AROUND 20 KTS FOR NOW. WILL KEEP SEAS AROUND 3
TO 4 FEET. CONDITIONS RELAX INTO FRIDAY MORNING.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE TO HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED
THROUGH MUCH OF THE PERIOD WITH HIGH PRESSURE ACROSS THE REGION.
LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RLG/SIPPRELL
NEAR TERM...DOODY/SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...RLG
AVIATION...KJC/RLG/SIPPRELL
MARINE...RLG/SIPPRELL
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1024 PM EDT WED AUG 20 2014
.SYNOPSIS...
DRIER AIR AND A BUILDING UPPER RIDGE JUST TO OUR WEST WILL REDUCE
THUNDERSTORM CHANCES THROUGH FRIDAY...AND LEAD TO HOTTER HIGH
TEMPERATURES. AN APPROACHING COLD FRONT AND INCREASING MOISTURE
WILL INCREASE THE THUNDERSTORM CHANCE OVER THE WEEKEND.
&&
.NEAR TERM /OVERNIGHT/...
SCATTERED CONVECTION HAS ENDED ACROSS THE AREA THIS EVENING.
STILL SOME ACTIVITY WELL UPSTREAM OVER ERN TN AND NRN GA BUT AT
THIS TIME EXPECT THOSE STORMS TO STAY EITHER WELL WEST OF THE
FORECAST AREA OR DISSIPATE BEFORE REACHING OUR AREA GIVEN THE
LATEST HRRR CYCLE. NOCTURNAL COOLING WITH DRY AIR ALOFT AND LIGHT
WIND SHOULD HELP SUPPORT AREAS OF FOG TOWARD SUNRISE. OVERNIGHT
LOWS IN THE IN THE LOWER AND MIDDLE 70S STILL LOOK REASONABLE.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
UPPER RIDGE WILL BUILD JUST TO OUR WEST. THIS AND A LOW LEVEL
DOWNSLOPE FLOW WILL LEAD TO WARMING TEMPS. MODELS CONTINUE TO
INDICATE MAX TEMPS NEAR 100 DEGREES MOST AREAS...AND CONTINUE TO
INDICATES DEW POINTS MIXING DOWN INTO THE MID TO UPPER 60S ACROSS
THE NORTHERN AND WESTERN COUNTIES TO NEAR 70 OR LOWER 70S ACROSS
THE SOUTHEAST MIDLANDS. THIS KEEPS HEAT INDICES JUST BELOW OUR
HEAT ADVISORY CRITERIA OF 110F. ONLY SLIGHT CHANCE OF
SHOWERS/TSTMS EXPECTED DUE TO BUILDING RIDGE ALOFT...AND FAIRLY
DRY LOW LEVEL AIR LEADING TO AND HIGH LEVELS OF FREE
CONVECTION/HIGH CONVECTIVE TEMPS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
UPPER RIDGE TO OUR WEST WITH UPPER TROUGH AND CLOSED LOW TO OUR
NE...PROVIDING A NW FLOW ALOFT FOR OUR FA. SOME TIMING
UNCERTAINTIES WITH A BACK DOOR FRONT. MODELS TRENDING A LITTLE
SLOWER WITH IT OF LATE...WITH POSSIBILITY THAT IT MAY NOT MAKE IT
TO OUR FA UNTIL SATURDAY AFTERNOON OR EVENING...SLOWLY PUSHING
SOUTH THROUGH SUNDAY. INCREASING POPS/THUNDER CHANCE ALONG AND
SOUTH OF THE BOUNDARY...WITH COOLER TEMPS NORTH OF IT. FRONT TO
PUSH TO OUR SOUTH EARLY NEXT WEEK...WITH SURFACE AND UPPER RIDGE
OVER THE EASTERN SEABOARD.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
EXPECT MAINLY VFR CONDITIONS THROUGH THE PERIOD.
BROKEN CIRRUS FROM CONVECTIVE DEBRIS WILL MOVE THROUGH THE REGION
EARLY TONIGHT...WHICH WILL HELP TO KEEP CONDITIONS VFR THROUGH
MIDNIGHT. LATE TONIGHT THOSE CLOUDS MAY THIN ENOUGH THAT WITH
LIGHT WINDS AND LOW-LEVEL MOISTURE IN PLACE...SOME MVFR FOG MAY BE
ABLE TO FORM AT AGS/DNL/OGB. CAE/CUB MAY SEE VISIBILITIES AT
SUNRISE AROUND 5-6SM. ALTHOUGH GUIDANCE CONTINUE TO TREND TOWARDS
VFR AT ALL SITES...AM SLIGHTLY MORE CONFIDENT IN MVFR AT AGS/DNL
DUE TO EARLIER RAINFALL ACROSS THAT AREA...THAT IS IF CLOUDS CAN
THIN ENOUGH. HEATING AND MIXING SHOULD DISSIPATE ANY FOG
BEGINNING AROUND 13Z. WINDS THROUGH THE PERIOD SHOULD REMAIN
GENERALLY LIGHT AND VARIABLE DUE TO A WEAK PRESSURE GRADIENT.
EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE
NIGHT AND EARLY MORNING FOG THROUGH THE PERIOD. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
940 AM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER TROUGH AND STRONG HEATING WILL SUPPORT SCATTERED
THUNDERSTORMS THIS AFTERNOON INTO THE EVENING. DRIER AIR AND A
BUILDING UPPER RIDGE JUST TO OUR WEST WILL REDUCE THUNDERSTORM
CHANCES WEDNESDAY AND THURSDAY...AND LEAD TO HOTTER HIGH
TEMPERATURES. AN APPROACHING COLD FRONT AND INCREASING MOISTURE
WILL INCREASE THE THUNDERSTORM CHANCE OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
TODAY...SCATTERED SHOWERS WERE MOVING INTO THE AREA THIS MORNING
ASSOCIATED WITH LIFT AHEAD OF A MID-LEVEL SHORTWAVE TROUGH. THE
TROUGH PLUS HEATING AND CONVERGENCE INTO THE LEE-SIDE SURFACE
TROUGH SHOULD HELP SUPPORT THUNDERSTORMS LATER TODAY. THE HIGH
RESOLUTION MODELS INDICATE SCATTERED COVERAGE. THE COVERAGE WILL
PROBABLY REMAIN LIMITED BECAUSE MUCH OF THE UPPER-LEVEL LIFT AHEAD
OF THE SHORTWAVE TROUGH WILL LIKELY OCCUR EARLY AND BEFORE MAXIMUM
HEATING. ALSO...CONVERGENCE INTO THE SURFACE FEATURE SHOULD REMAIN
WEAK AND FORECAST SOUNDINGS SHOW WESTERLY FLOW THROUGH A DEEP
LAYER WHICH SHOULD HELP KEEP MOISTURE SOMEWHAT SHALLOW.
SIGNIFICANT UNI-DIRECTIONAL WIND SHEAR WITH 5000-FOOT WINDS NEAR
30 KNOTS MAINLY IN THE SOUTH PART AND STEEP LOW-LEVEL LAPSE RATES
MAY HELP SUPPORT STRONG WIND GUSTS WITH ANY THUNDERSTORMS. STRONG
MIXING WILL BRING GUSTY WINDS. USED THE GFS LAMP AND NAM BUFKIT
MOMENTUM-TRANSFER TOOL FOR THE WIND GUST FORECAST. USED THE
WARMER TEMPERATURE GUIDANCE BECAUSE OF THE WESTERLY FLOW.
TONIGHT...THE MODELS MAINTAIN SURFACE TROUGHING. HOWEVER...BELIEVE
THE THUNDERSTORM CHANCE IS LOW BECAUSE OF SHALLOW MOISTURE IN THE
WAKE OF THE MID-LEVEL SHORTWAVE TROUGH AND NOCTURNAL COOLING. THE
NAM AND GFS MOS HAVE POPS 20 TO 30 PERCENT...MAINLY IN THE EVENING
CLOSER TO THE TIME OF HEATING. THE TEMPERATURE GUIDANCE WAS CLOSE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
UPPER RIDGE WILL BUILD JUST TO OUR WEST WEDNESDAY AS THE UPPER
TROUGH MOVES OFF THE COAST. WARMING 850MB TEMPERATURES AND A LOW
LEVEL DOWNSLOPE FLOW WILL RESULT IN MAX TEMPERATURES PUSHING 100
DEGREES WEDNESDAY AND THURSDAY. GUIDANCE INDICATES DEW POINTS
MIXING DOWN INTO THE MID TO UPPER 60S ACROSS THE NORTHERN AND
WESTERN COUNTIES TO NEAR 70 ACROSS THE SOUTHEAST MIDLANDS. THIS
SHOULD KEEP HEAT INDICES JUST BELOW OUR HEAT ADVISORY CRITERIA OF
110F. ONLY SLIGHT CHANCE OF SHOWERS/TSTMS EXPECTED BOTH WEDNESDAY
AND THURSDAY DUE TO DRIER AIR AND BUILDING RIDGE ALOFT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
UPPER RIDGE TO OUR WEST WITH UPPER TROUGH AND CLOSED LOW TO OUR
NE...PROVIDING A NW FLOW ALOFT FOR OUR FA. SOME TIMING
UNCERTAINTIES...BUT MODELS SUGGEST A BACK DOOR FRONT WILL MOVE
DOWN THE EAST COAST...REACHING OUR FA SOME TIME THIS WEEKEND. THIS
WOULD INCREASE POPS ALONG AND SOUTH OF THE BOUNDARY...AND LEAD TO
COOLER TEMPS NORTH OF IT. WILL MAINTAIN TREND IN THE ONGOING
FORECAST OF POPS TRENDING HIGHER AND TEMPS TRENDING LOWER DURING
THAT TIME.
&&
.AVIATION /13Z TUESDAY THROUGH SATURDAY/...
EXPECT MAINLY VFR CONDITIONS DURING THE TAF PERIOD.
CLOUDINESS ASSOCIATED WITH A MID-LEVEL SHORTWAVE TROUGH AND H85
WIND SPEED CONVERGENCE MAY BRING A PERIOD OF MVFR CEILINGS AT
SOME OF THE TAF SITES. HEATING AND MIXING SHOULD HELP DIMINISH
THIS CLOUDINESS BY MIDDAY. SATELLITE TRENDS AND THE HRRR GUIDANCE
INDICATED A PERIOD OF MVFR AT AGS...DNL...CAE...AND CUB.
SCATTERED SHOWERS WERE MOVING INTO THE AREA THIS MORNING
ASSOCIATED WITH LIFT AHEAD OF THE MID-LEVEL SHORTWAVE TROUGH. THE
TROUGH PLUS HEATING AND CONVERGENCE INTO THE LEE-SIDE SURFACE
TROUGH SHOULD HELP SUPPORT THUNDERSTORMS LATER TODAY. THE HIGH
RESOLUTION MODELS INDICATE SCATTERED COVERAGE. THE COVERAGE WILL
PROBABLY REMAIN LIMITED BECAUSE MUCH OF THE UPPER-LEVEL LIFT AHEAD
OF THE SHORTWAVE TROUGH WILL LIKELY OCCUR EARLY AND BEFORE MAXIMUM
HEATING. ALSO...CONVERGENCE INTO THE SURFACE FEATURE SHOULD REMAIN
WEAK AND FORECAST SOUNDINGS SHOW WESTERLY FLOW THROUGH A DEEP
LAYER WHICH SHOULD HELP KEEP MOISTURE SOMEWHAT SHALLOW. THE
THUNDERSTORM CHANCE IS TOO LOW TO INCLUDE IN THE TERMINAL
FORECASTS AT THIS TIME BECAUSE OF THE SCATTERED COVERAGE AND
TIMING UNCERTAINTY. SIGNIFICANT UNI-DIRECTIONAL WIND SHEAR WITH
5000-FOOT WINDS NEAR 30 KNOTS MAINLY IN THE SOUTH PART AND STEEP
LOW-LEVEL LAPSE RATES MAY HELP SUPPORT STRONG WIND GUSTS NEAR ANY
THUNDERSTORMS. STRONG MIXING WILL BRING GUSTY WINDS. USED THE GFS
LAMP AND NAM BUFKIT MOMENTUM-TRANSFER TOOL FOR THE WIND GUST
FORECAST. DRYING ALOFT AND LINGERING LOW-LEVEL MOISTURE PLUS
NOCTURNAL COOLING MAY HELP SUPPORT FOG TONIGHT. MOST OF THE NAM
AND GFS MOS INDICATE MVFR FOG. FOG WILL LIKELY BE LIMITED BY SOME
MIXING.
EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE
NIGHT AND EARLY MORNING FOG THROUGH THE PERIOD. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
808 AM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER TROUGH AND INCREASING MOISTURE WILL BRING THE CHANCE FOR
SHOWERS AND THUNDERSTORMS TODAY. DRIER AIR AND A BUILDING UPPER
RIDGE JUST TO OUR WEST WILL REDUCE AFTERNOON THUNDERSTORM CHANCES
WEDNESDAY AND THURSDAY...AND LEAD TO INCREASING HIGH TEMPERATURES.
AN APPROACHING BACKDOOR FRONT AND INCREASING MOISTURE WILL LEAD TO
GREATER THUNDERSTORM CHANCES OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
A SHORTWAVE TROUGH CROSSING NORTHERN GA IN NEAR ZONAL FLOW THIS
MORNING IS EXPECTED TO MOVE INTO WESTERN SC AROUND SUNRISE AND
CROSS THE FORECAST AREA TODAY. HAVE INCREASED POPS TO THE 40 TO 50
PERCENT RANGE. WEAK TO MODERATE INSTABILITY IS FORECAST ALONG WITH
PWAT INCREASING TO AROUND OR ABOVE 2.00 INCHES THIS AFTERNOON.
CANNOT RULE OUT AN ISOLATED STRONG TO SEVERE STORM THIS AFTERNOON
GIVEN INVERTED V SIGNATURE INDICATED IN FORECAST SOUNDINGS FOR THE
AFTERNOON. DAMAGING WIND GUSTS WOULD BE THE MAIN THREAT IF A
SEVERE STORM DEVELOPS WITH LARGE HAIL GENERALLY UNLIKELY DUE TO
FREEZING LEVEL HEIGHT OVER 15KFT. THE CENTRAL AND SOUTHEASTERN
MIDLANDS AND CSRA LOOK TO BE THE MOST FAVORABLE LOCATION FOR
STORMS TODAY. KEPT AFTERNOON HIGHS ON THE WARM SIDE OF GUIDANCE.
CONVECTION WILL DECREASE EARLY THIS EVENING AS THE SHORT WAVE
MOVES EAST OF THE AREA. OVERNIGHT LOWS ARE EXPECTED TO FALL INTO
THE LOWER 70S AS SKIES BECOME MOSTLY CLEAR.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
UPPER RIDGE WILL BUILD JUST TO OUR WEST WEDNESDAY AS THE UPPER
TROUGH MOVES OFF THE COAST. WARMING 850MB TEMPERATURES AND A LOW
LEVEL DOWNSLOPE FLOW WILL RESULT IN MAX TEMPERATURES PUSHING 100
DEGREES WEDNESDAY AND THURSDAY. GUIDANCE INDICATES DEWPOINTS
MIXING DOWN INTO THE MID TO UPPER 60S ACROSS THE NORTHERN AND
WESTERN COUNTIES TO NEAR 70 ACROSS THE SOUTHEAST MIDLANDS. THIS
SHOULD KEEP HEAT INDICES JUST BELOW OUR HEAT ADVISORY CRITERIA OF
110F. ONLY SLIGHT CHANCE OF SHOWERS/TSTMS EXPECTED BOTH WEDNESDAY
AND THURSDAY DUE TO DRIER AIR AND BUILDING RIDGE ALOFT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
NO SIGNIFICANT CHANGES MADE TO THE LONG TERM FORECAST.
PREVIOUS DISCUSSION:
UPPER RIDGE TO OUR WEST WITH UPPER TROUGH AND CLOSED LOW TO OUR
NE...PROVIDING A NW FLOW ALOFT FOR OUR FA. SOME TIMING
UNCERTAINTIES...BUT MODELS SUGGEST A BACK DOOR FRONT WILL MOVE
DOWN THE EAST COAST...REACHING OUR FA SOME TIME THIS WEEKEND. THIS
WOULD INCREASE POPS ALONG AND SOUTH OF THE BOUNDARY...AND LEAD TO
COOLER TEMPS NORTH OF IT. WILL MAINTAIN TREND IN THE ONGOING
FORECAST OF POPS TRENDING HIGHER AND TEMPS TRENDING LOWER DURING
THAT TIME.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
EXPECT MAINLY VFR CONDITIONS DURING THE TAF PERIOD.
H85 WIND SPEED CONVERGENCE MAY HELP SUPPORT A PERIOD OF MVFR
CEILINGS THIS MORNING. THE 08Z HRRR INDICATED MVFR CEILINGS FOR A
SHORT PERIOD OF TIME THIS MORNING AT AGS AND DNL. HEATING AND
MIXING SHOULD HELP DIMINISH THIS CLOUDINESS LATER THIS MORNING.
SCATTERED SHOWERS WERE MOVING INTO THE AREA THIS MORNING
ASSOCIATED WITH LIFT AHEAD OF A MID-LEVEL SHORTWAVE TROUGH.
THE TROUGH PLUS HEATING AND CONVERGENCE INTO THE LEE-SIDE SURFACE
TROUGH SHOULD HELP SUPPORT THUNDERSTORMS LATER TODAY. THE HIGH
RESOLUTION MODELS INDICATE SCATTERED COVERAGE. THE COVERAGE WILL
PROBABLY REMAIN LIMITED BECAUSE MUCH OF THE UPPER-LEVEL LIFT AHEAD
OF THE SHORTWAVE TROUGH WILL LIKELY OCCUR EARLY BEFORE MAXIMUM
HEATING. ALSO...CONVERGENCE INTO THE SURFACE FEATURE SHOULD REMAIN
WEAK AND FORECAST SOUNDINGS SHOW WESTERLY FLOW THROUGH A DEEP
LAYER WHICH SHOULD HELP KEEP MOISTURE SOMEWHAT SHALLOW. THE
THUNDERSTORM CHANCE IS TOO LOW TO INCLUDE IN THE TERMINAL
FORECASTS AT THIS TIME BECAUSE OF THE SCATTERED COVERAGE AND TIMING
UNCERTAINTY. SIGNIFICANT UNI-DIRECTIONAL WIND SHEAR WITH
5000-FOOT WINDS NEAR 30 KNOTS MAINLY IN THE SOUTH PART AND STEEP
LOW-LEVEL LAPSE RATES MAY HELP SUPPORT STRONG WIND GUSTS NEAR ANY
THUNDERSTORMS. STRONG MIXING WILL BRING GUSTY WINDS. USED THE GFS
LAMP AND NAM BUFKIT MOMENTUM-TRANSFER TOOL FOR THE WIND GUST
FORECAST.
EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE
NIGHT AND EARLY MORNING FOG THROUGH THE PERIOD. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
116 AM EDT TUE AUG 19 2014
.PREV DISCUSSION... /ISSUED 936 PM EDT MON AUG 18 2014/
UPDATE...
HAVE MADE SEVERAL CHANGES TO POPS THROUGH THE EVENING TO ACCOUNT
FOR TRENDS. MOST CONVECTION IS DYING OFF NOW...WITH ONLY LIGHT
RAIN REMAINING...BUT THE LEFTOVER MISSISSIPPI VALLEY MCV IS
WORKING ITS WAY ACROSS NORTHERN ALABAMA AT AFD TIME AND SHOULD
PUSH INTO NORTH GEORGIA IN THE NEXT FEW HOURS. AGAIN HAVE TRIED TO
ADJUST POPS TO ACCOUNT FOR THIS. AIRMASS IS PRETTY STABLE BEHIND
CONVECTION THIS EVENING SO THINK SEVERE POTENTIAL WITH ANY MCV
CONVECTION WOULD BE PRETTY LOW...HEAVY RAIN WOULD BE THE MORE
SIGNIFICANT THREAT.
UPDATED PRODUCTS OUT SHORTLY.
TDP
PREV DISCUSSION... /ISSUED 750 PM EDT MON AUG 18 2014/
PREV DISCUSSION... /ISSUED 320 PM EDT MON AUG 18 2014/
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
STALLED FRONTAL BOUNDARY STRETCHES FROM THE TN VALLEY TO THE
SOUTHERN MID ATLANTIC STATES. A HIGH PRESSURE RIDGE IS SITUATED
ACROSS NORTHERN FL. 500MB ANALYSIS AND WV LOOP SHOWS A POTENT
SHORTWAVE MOVING EAST ACROSS NORTHERN MS. THIS FEATURE WILL BE THE
FOCUS FOR LATE AFTERNOON AND EVENING CONVECTION ACROSS THE CWFA.
THE 16Z HRRR HAS THE BEST HANDLE ON THE ONGOING CONVECTION THIS
AFTERNOON. HAVE TRIED TO ORIENT THE POPS ACCORDING TO CURRENT RADAR
TRENDS AND CLOSE TO THE HRRR SOLUTION. GOOD INSTABILITY DOES EXIST
AT THE SURFACE...BUT LAPSE RATES REMAIN POOR UNTIL THE COLD POOL
ALOFT MOVES OVERHEAD. BY THE TIME THE SHORTWAVE NEARS THE
CWFA...INSTABILITY HAS DECREASED WITH THE LOSS OF HEATING.
HOWEVER...WITH UNIDIRECTIONAL FLOW...STORMS MAY MOVE REPEATEDLY OVER
THE SAME AREAS...WITH LOCALLY HEAVY RAINFALL POSSIBLE. AREAS TO THE
NORTH RECEIVED ONE TO TWO INCHES OF RAINFALL OVERNIGHT/EARLY THIS
MORNING...SO ANY TRAINING STORMS OR HEAVY RAINFALL MAY CAUSE SOME
LOCALIZED FLOODING.
BY EARLY TUESDAY...THE POTENT EVENING/OVERNIGHT SHORTWAVE WILL HAVE
MOVED OFF TO THE EAST. MODELS ARE PROGGING ANOTHER...WEAKER...
SHORTWAVE TO MOVE EAST IN THE FLOW TOMORROW. CONFIDENCE IS LOW ON
EXACTLY WHERE CONVECTION WILL DEVELOP TOMORROW.
NLISTEMAA
LONG TERM /WEDNESDAY THROUGH MONDAY/...
LONG TERM FORECAST IS ON TRACK AND HAVE NOT MADE SIGNIFICANT
ADJUSTMENTS. ONE ADDITIONAL POINT TO NOTE IS THAT HEAT INDEX VALUES
ARE CREEPING ABOVE 100 DEGREES SOUTH OF AN ATLANTA TO ATHENS
LINE...WITH PORTIONS OF CENTRAL GEORGIA APPROACHING 105 DEGREES
DURING THE SECOND HALF OF THE WEEK. IF THIS TREND CONTINUES...MAY
NEED A HEAT ADVISORY FOR THESE 105-108 DEGREE VALUES ACROSS THE
SOUTHEAST PART OF THE CWA.
11/ATWELL
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
00Z GFS AND ECMWF ARE IN UNCOMMONLY GOOD AGREEMENT THROUGH THE
EXTENDED FORECAST PERIOD AND CONTINUE THE RECENT TREND OF BUILDING
UPPER-LEVEL HIGH PRESSURE INTO THE CENTRAL GULF COAST REGION AND
LOWER MISSISSIPPI VALLEY FROM MID-WEEK THROUGH NEXT WEEKEND. BY THE
WEEKEND THE UPPER RIDGE IS QUITE STRONG...BUT GEORGIA REMAINS ON THE
EASTERN PERIPHERY. THIS SHOULD ALLOW VERY WARM TEMPERATURES AND
INHIBIT DIURNAL CONVECTION SOMEWHAT...BUT I DO NOT BELIEVE THE
FORECAST AREA IS CLOSE ENOUGH TO THE CENTER OF THE RIDGE TO
ELIMINATE POPS ALTOGETHER.
20
&&
.AVIATION...
06Z UPDATE...
POTENTIAL FOR INCREASING LIFR-MVFR CEILINGS ACROSS THE TAF SITES
WITH SOME MVFR VSBYS DUE TO FOG. IMPROVEMENT EXPECTED TO VFR DURING
THE LATER MORNING. POTENTIAL FOR SHOWERS AND THUNDERSTORMS ALMOST
ANY TIME TODAY. SURFACE WINDS LIGHT WSW INCREASING TO MAINLY WEST
AROUND 10 KTS WITH SOME GUSTS AROUND 20 KTS.
//ATL CONFIDENCE...06Z UPDATE...
LOW CONFIDENCE ON CEILINGS/VSBYS AND IMPACTS OF THUNDERSTORMS TODAY.
HIGH CONFIDENCE ON WINDS.
BDL
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 91 72 97 72 / 40 30 10 5
ATLANTA 88 73 94 75 / 40 30 10 5
BLAIRSVILLE 84 67 90 68 / 40 30 20 10
CARTERSVILLE 89 71 94 71 / 40 30 10 5
COLUMBUS 92 73 96 75 / 40 30 10 5
GAINESVILLE 89 71 94 73 / 40 30 10 10
MACON 92 72 97 74 / 40 30 10 5
ROME 89 71 95 71 / 40 30 20 10
PEACHTREE CITY 89 71 94 72 / 40 30 10 5
VIDALIA 95 74 97 76 / 40 30 20 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BDL
LONG TERM....20
AVIATION...BDL
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1007 PM CDT WED AUG 20 2014
.DISCUSSION...
819 PM CDT
FOR EVENING UPDATE...
HAVE MADE SOME FAIRLY SIGNIFICANT UPDATES TO SHOWER/THUNDERSTORM
POPS AND TIMING OVERNIGHT...BASED ON OBSERVATIONAL DATA AND HIGH
RES MODEL TRENDS OVER THE PAST SEVERAL HOURS. OVERALL...HAVE
TRIMMED BACK POPS TO ISOLATED/SCATTERED SHOWERS THROUGH THE
REMAINDER OF THIS EVENING...WITH GRADUAL INCREASE IN SCATTERED
SHOWER/THUNDERSTORM COVERAGE AFTER MIDNIGHT...BUT WITH GREATEST
POTENTIAL LOOKING LIKE THURSDAY MORNING WITH EXPECTED MCS REMNANTS
ARRIVING FROM MINNESOTA.
A STATIONARY FRONT STRETCHES FROM SOUTH DAKOTA SOUTHEAST ACROSS
NORTHERN MISSOURI AND INTO THE LOWER OHIO VALLEY THIS EVENING.
NORTH OF THE SURFACE BOUNDARY...AN AREA OF CLOUDS AND ISOLATED
SHOWERS HAS PERSISTED WITHIN THE ELEVATED BAROCLINIC ZONE...WITH A
COUPLE OF WEAK SHORT WAVES NOTED TOPPING MID-LEVEL SHORT WAVE
RIDGE AXIS WHICH WAS ROUGHLY FROM ST LOUIS NORTHWEST INTO
SOUTHWEST MINNESOTA. MODEL GUIDANCE HAS BEEN VERY INSISTENT IN
DEVELOPING STRONG CONVECTION ALONG THIS ELEVATED BAROCLINIC ZONE
THIS EVENING INTO EARLY THURSDAY MORNING...THOUGH COMPARISON TO
OBSERVED RADAR/SATELLITE DATA SUGGESTS GUIDANCE HAS BEEN OVER
FORECASTING EXTENSIVE COVERAGE OF DEEP CONVECTION SO FAR.
WITH THE BEST LOW LEVEL JET FLOW AND SHORT WAVE FORCING CURRENTLY
ACROSS THE PLAINS AND ORIENTED INTO THE MID-MISSOURI VALLEY
REGION...WOULD ANTICIPATE THE BEST AREA FOR STRONG CONVECTION TO
DEVELOP OVER THE NEXT FEW HOURS WOULD BE FROM NORTHEAST
NEBRASKA/SOUTHEAST SOUTH DAKOTA INTO WESTERN MINNESOTA/NORTHWEST
IOWA. WEAKER FORCING AND WEAKER WEST-SOUTHWEST LOW LEVEL FLOW INTO
BAROCLINIC ZONE EAST OF THE MISSISSIPPI...WHICH SUGGESTS LESS
INTENSIVE DEVELOPMENT HERE. DEVELOPMENT STILL EXPECTED ACROSS THE
AREA DURING THE NIGHT AS THE LOW LEVEL WEST-SOUTHWESTERLY FLOW
STRENGTHENS A BIT...THOUGH CONFIDENCE IS FAIRLY LOW ON AMOUNT OF
COVERAGE. HRRR HAS CONSISTENTLY SHOWN THE SCENARIO OF AN MCS
DEVELOPING OUT OF ANTICIPATED CONVECTION OVER THE PREVIOUSLY
MENTIONED MID-UPPER MISSOURI VALLEY REGION OVERNIGHT...WHICH WOULD
APPROACH THE FORECAST AREA FROM THE NORTHWEST TOWARD MORNING. WITH
ALL OF THIS IN MIND...HAVE TRIMMED BACK POPS OVERNIGHT AND
ESPECIALLY THIS EVENING...GRADUALLY INCREASING CHANCES AFTER
MIDNIGHT. MAINTAINED LIKELY POPS THURSDAY MORNING...WITH MCS
REMNANTS EXPECTED TO PERHAPS PRESENT THE GREATEST RAINFALL
PROBABILITY. 00Z SOUNDINGS UPSTREAM OF OUR FORECAST AREA DEPICT
PWATS IN THE 1.5-1.6 INCH RANGE SO STILL A LOCALLY HEAVY RAINFALL
THREAT FROM STRONGER CONVECTION ESPECIALLY DURING THE PRE-DAWN
THROUGH MID-MORNING THURSDAY PERIOD.
ALSO...WITH CLOUDS AND LIGHT WEST-SOUTHWEST FLOW BUMPED MIN TEMPS
JUST A BIT OVERNIGHT.
RATZER
//PREV DISCUSSION...
320 PM CDT
MAIN FORECAST CONCERNS ARE WITH PERSISTENT CHANCES FOR SHOWERS AND
THUNDERSTORMS OVER THE NEXT SEVERAL DAYS...WITH SOME POTENTIAL FOR
STRONG/SEVERE STORMS BUT WITH HIGHER CONFIDENCE FOR HEAVY
RAINFALL. WITH CONFIDENCE STILL LOWER ON COVERAGE AND PLACEMENT
OF STORMS TONIGHT...HAVE NOT ISSUED A FLOOD WATCH AT THIS TIME
BUT DID ISSUE AN SPS TO RAISE AWARENESS FOR THIS POTENTIAL.
IN THE NEAR TERM...QUIETER CONDITIONS ONGOING THIS AFTERNOON WITH
THE BULK OF THE CWA DRY. LATEST RADAR IMAGERY DEPICTING STEADY
STREAM OF SHOWERS AND THUNDERSTORMS STILL MOVING SOUTHEAST THROUGH
EASTERN IOWA AND WEST CENTRAL ILLINOIS...BUT WITH COVERAGE AND
INTENSITY DIMINISHING. SHORT TERM GUIDANCE STILL TRYING TO BRING
PRECIP ACROSS NORTH/NORTHEAST ILLINOIS LATE THIS AFTERNOON INTO
THE EARLY EVENING BUT DONT REALLY AGREE. FEEL THAT CONDITIONS WILL
REMAIN DRY THROUGH EARLY THIS EVENING FOR MOST LOCATIONS WITH THE
EXCEPTION FOR AREAS ALONG AND SOUTHWEST OF LINE FROM OREGON TO
WATSEKA...WHERE STEERING FLOW COULD DRIFT A STRAY SHOWER OR
THUNDERSTORM BRIEFLY OVER THAT AREA. ELSEWHERE...BRIEF AND LIGHT
RETURNS CONTINUE TO SHOW ON RADAR OVER NORTHEAST ILLINOIS IN AND
AROUND WEAK CONVERGENCE ALONG LAKE BREEZE IN FAR SOUTHEAST
WISCONSIN AND FAR NORTHEAST ILLINOIS. A LACK OF ANY INHIBITION
THIS AFTERNOON AND THIS WEAK CONVERGENCE COULD ALLOW FOR CONTINUED
DEVELOPMENT OF THESE LIGHT SHOWERS THIS AFTERNOON.
TONIGHT...INCREASING CHANCES FOR SHOWERS/THUNDERSTORMS WILL OCCUR
THROUGHOUT THE NIGHT AS UPSTREAM UPPER LEVEL RIDGE CONTINUES TO
BUILD ACROSS THE REGION WITH THE RIDGE AXIS SHIFTING EAST TOWARDS
THE CWA...AND WHILE SURFACE WARM FRONT SITUATED OVER THE SOUTHERN
CWA LIFTS NORTH. UPSTREAM SHORTWAVE ENERGY NOTED ON CURRENT WATER
VAPOR IMAGERY WILL RIDE ALONG THIS RIDGE AND MOVE ACROSS THE CWA
TONIGHT INTO EARLY THURSDAY MORNING. MEANWHILE...STRENGTHENING LLJ
WILL BEGIN VEERING THIS EVENING AND THEN BE ORIENTED TOWARDS THE
CWA LATER IN THE NIGHT. THIS WILL ALL PROVIDE FOCUS FOR
THUNDERSTORM DEVELOPMENT OVERNIGHT ESPECIALLY AS WAA RAMPS UP WITH
THE VEERING/STRENGTHENING LLJ. WEAK TO MODERATE INSTABILITY AXIS
WILL BE IN PLACE TONIGHT WITH POTENTIAL FOR SOME STEEPER MID LAPSE
RATES...CURRENTLY OBSERVED JUST SOUTH OF THE CWA...TO LINGER
TONIGHT. CONFIDENCE IS NOT OVERLY GREAT WITH REGARDS TO THE
INTENSITY OF STORMS TONIGHT BUT WITH THE PREVIOUSLY MENTIONED
FORCING MECHANISMS COMING TOGETHER OVERHEAD TONIGHT...WOULD EXPECT
THE POSSIBILITY FOR AT LEAST AN ISOLATED STRONGER STORM TO PROVIDE
A HAIL/WIND THREAT. FEEL THAT THE BEST CHANCES FOR THIS
POSSIBILITY COULD OCCUR OVER THE SOUTH/SOUTHWEST HALF OF THE
CWA...WHERE THE STEEPER MID LEVEL LAPSE RATES WILL POSSIBLY RESIDE
PER CURRENT ANALYSIS AND SREF GUIDANCE.
A GROWING CONCERN WILL BE FOR THE POTENTIAL OF HEAVY RAINFALL AND
LOCALIZED FLOODING WITH THESE STORMS TONIGHT INTO EARLY THURSDAY.
GUIDANCE CONTINUES TO VARY WITH REGARD TO OVERALL COVERAGE AND
EXACT PLACEMENT OF BEST DEVELOPMENT TONIGHT...AND WITH MY
CONFIDENCE NOT THE GREATEST WITH REGARDS TO RESIDENCE TIME OF ANY
STORM. NONETHELESS...OBSERVED HIGH PWAT AXIS OF 1.5 TO 2 INCHES
CURRENTLY OBSERVED JUST TO THE SOUTHWEST OF THE CWA WILL SHIFT
NORTHEAST OVER THE CWA TONIGHT...AND WITH THIS HIGHEST AXIS
EXPECTED TO BE CENTERED OVERHEAD TONIGHT. WITH THESE HIGH PWATS IN
PLACE AND WITH SURFACE DEWPOINTS AROUND 70 DEG AND 850MB DEWPOINTS
APPROACHING 15-16C...ANY STORM WILL EASILY HAVE THE POTENTIAL TO
PRODUCE HEAVY DOWNPOURS. DESPITE THESE CONCERNS...I ONCE AGAIN
DONT HAVE THE GREATEST CONFIDENCE OF COVERAGE/PLACEMENT AND HAVE
DECIDED TO HOLD OFF ON ANY FLOOD WATCH AT THIS TIME. THIS WILL
NEED TO CONTINUE TO BE CLOSELY MONITORED THIS EVENING BUT IN THE
NEAR TERM HAVE DECIDED TO ISSUE AN SPS FOR THIS POSSIBILITY. STILL
THINK THAT WHAT OCCURRED JUST TO THE WEST/SOUTHWEST TODAY COULD
EASILY OCCUR TONIGHT INTO THURSDAY OVER THE CWA...ALTHOUGH WITH
THE POSSIBILITY FOR A SLIGHTLY DIFFERENT SETUP PROVIDING
BETTER/STRONGER THUNDERSTORM DEVELOPMENT.
ANY LINGERING STORMS THURSDAY MORNING WILL SHIFT EAST AND
NORTHEAST OF THE CWA THROUGH MID DAY WITH A POSSIBILITY FOR
CONTINUED HEAVY RAINFALL. THESE DEPARTING STORMS COULD ALLOW FOR
CLEARING SKIES AND THE ENVIRONMENT TO DESTABILIZE ONCE AGAIN
DURING MID DAY AND EARLY AFTERNOON...WITH THE POSSIBILITY FOR
THUNDERSTORMS TO REDEVELOP ALONG LIFTING FRONTAL BOUNDARY.
CLEARING WILL BE KEY WITH POTENTIAL FOR INTENSITY OF THESE STORMS
ON THURSDAY BUT WITH STRONG TO SEVERE STORMS POSSIBLE...ESPECIALLY
IF A GOOD AMOUNT OF HEATING COULD OCCUR. FOCUS FOR THUNDERSTORMS
WILL CONTINUE THURSDAY NIGHT AS WELL...WITH HIGH MOISTURE CONTENT
AIR STILL IN PLACE. THIS WILL ALSO CONTINUE CONCERNS FOR HEAVY
RAINFALL ACROSS THE AREA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* CHANCE FOR TSRA THURSDAY MORNING.
KJB
//DISCUSSION...UPDATED 03Z..
WE HAVE BACKED OFF A BIT ON TS CHANCES LATE TONIGHT AS IT APPEARS
THE MAIN FOCUS OF SCT DEVELOPMENT MAY REMAIN TO THE SOUTHWEST OF
THE MAIN TERMINALS. HOWEVER...CONVECTIVE ACTIVITY DEVELOPING TO
OUR NORTHWEST ACROSS SOUTHERN MN AND NORTHERN IOWA COULD MOVE OVER
THE AREA SHORTLY AFTER DAYBREAK THURSDAY...SO I WILL LEAVE THE
CHANCES FOR TS IN AFTER 12 UTC.
KJB
//DISCUSSION...UPDATED 00Z...
THE MAIN AVIATION WEATHER CONCERNS THROUGH THE PERIOD WILL BE
CHANCES AND TIMING OF CONVECTIVE ACTIVITY.
UNFORTUNATELY CONFIDENCE IN TIMING OF THUNDER AT THE TERMINALS
REMAINS LOW AT THIS TIME. A WARM FRONT IS EXPECTED TO LIFT NORTHWARD
ACROSS THE AREA BY THURSDAY...WITH A WARM...HUMID AND UNSTABLE
ATMOSPHERE EXPECTED. IT APPEARS THE MAIN FOCUS FOR THUNDERSTORMS
TONIGHT WILL BE ACROSS SOUTHERN MN AND PORTIONS OF IOWA ALONG THE
BETTER FOCUS OF A LOW LEVEL JET. HOWEVER...ADDITIONAL SCATTERED
SHOWERS AND STORMS COULD ALSO DEVELOP TONIGHT ALONG AND AHEAD OF THE
WARM FRONTAL BOUNDARY...ACROSS PORTIONS OF NORTHERN ILLINOIS. THE
MAIN QUESTION WITH THESE STORMS ARE HOW FAR NORTHEASTWARD THEY REACH
LATER TONIGHT...AND HENCE IF THEY WILL DIRECTLY IMPACT THE
TERMINALS. THE THREAT FOR THUNDERSTORMS WILL CONTINUE DURING THE
MORNING THURSDAY...WITH THE POTENTIAL FOR REMNANTS OF THE SOUTHERN
MN CONVECTION MOVING SOUTHEASTWARD ACROSS THE AREA AFTER
DAYBREAK.
WITH OVERALL CONFIDENCE REMAINING LOW TO MODERATE...I HAVE MADE
LITTLE CHANGES TO THE GOING FORECAST.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* LOW WITH TSRA LATE...LOW-MEDIUM WITH TSRA AFTER DAY BREAK
THROUGH LATE THURSDAY MORNING.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...PERIODIC CHANCES FOR TSRA.
KJB
&&
.MARINE...
158 PM CDT
FAIRLY LIGHT WIND REGIME IS EXPECTED THROUGH THE WEEKEND WITH WEAK
PRESSURE GRADIENT EXPECTED WITH HIGH PRESSURE OVER THE ST LAWRENCE
VALLEYS REGION AND A TROUGH OF LOW PRESSURE OVER THE NORTHERN AND
CENTRAL PLAINS. A QUASI-STATIONARY WARM FRONT WILL EXTEND EAST FROM
THE LOW INTO THE LOWER GREAT LAKES REGION...WITH THE POSITION OF THE
WARM FRONT LIKELY BEING MODULATED AT TIMES BY CONVECTIVE COMPLEXES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
819 PM CDT WED AUG 20 2014
.DISCUSSION...
819 PM CDT
FOR EVENING UPDATE...
HAVE MADE SOME FAIRLY SIGNIFICANT UPDATES TO SHOWER/THUNDERSTORM
POPS AND TIMING OVERNIGHT...BASED ON OBSERVATIONAL DATA AND HIGH
RES MODEL TRENDS OVER THE PAST SEVERAL HOURS. OVERALL...HAVE
TRIMMED BACK POPS TO ISOLATED/SCATTERED SHOWERS THROUGH THE
REMAINDER OF THIS EVENING...WITH GRADUAL INCREASE IN SCATTERED
SHOWER/THUNDERSTORM COVERAGE AFTER MIDNIGHT...BUT WITH GREATEST
POTENTIAL LOOKING LIKE THURSDAY MORNING WITH EXPECTED MCS REMNANTS
ARRIVING FROM MINNESOTA.
A STATIONARY FRONT STRETCHES FROM SOUTH DAKOTA SOUTHEAST ACROSS
NORTHERN MISSOURI AND INTO THE LOWER OHIO VALLEY THIS EVENING.
NORTH OF THE SURFACE BOUNDARY...AN AREA OF CLOUDS AND ISOLATED
SHOWERS HAS PERSISTED WITHIN THE ELEVATED BAROCLINIC ZONE...WITH A
COUPLE OF WEAK SHORT WAVES NOTED TOPPING MID-LEVEL SHORT WAVE
RIDGE AXIS WHICH WAS ROUGHLY FROM ST LOUIS NORTHWEST INTO
SOUTHWEST MINNESOTA. MODEL GUIDANCE HAS BEEN VERY INSISTENT IN
DEVELOPING STRONG CONVECTION ALONG THIS ELEVATED BAROCLINIC ZONE
THIS EVENING INTO EARLY THURSDAY MORNING...THOUGH COMPARISON TO
OBSERVED RADAR/SATELLITE DATA SUGGESTS GUIDANCE HAS BEEN OVER
FORECASTING EXTENSIVE COVERAGE OF DEEP CONVECTION SO FAR.
WITH THE BEST LOW LEVEL JET FLOW AND SHORT WAVE FORCING CURRENTLY
ACROSS THE PLAINS AND ORIENTED INTO THE MID-MISSOURI VALLEY
REGION...WOULD ANTICIPATE THE BEST AREA FOR STRONG CONVECTION TO
DEVELOP OVER THE NEXT FEW HOURS WOULD BE FROM NORTHEAST
NEBRASKA/SOUTHEAST SOUTH DAKOTA INTO WESTERN MINNESOTA/NORTHWEST
IOWA. WEAKER FORCING AND WEAKER WEST-SOUTHWEST LOW LEVEL FLOW INTO
BAROCLINIC ZONE EAST OF THE MISSISSIPPI...WHICH SUGGESTS LESS
INTENSIVE DEVELOPMENT HERE. DEVELOPMENT STILL EXPECTED ACROSS THE
AREA DURING THE NIGHT AS THE LOW LEVEL WEST-SOUTHWESTERLY FLOW
STRENGTHENS A BIT...THOUGH CONFIDENCE IS FAIRLY LOW ON AMOUNT OF
COVERAGE. HRRR HAS CONSISTENTLY SHOWN THE SCENARIO OF AN MCS
DEVELOPING OUT OF ANTICIPATED CONVECTION OVER THE PREVIOUSLY
MENTIONED MID-UPPER MISSOURI VALLEY REGION OVERNIGHT...WHICH WOULD
APPROACH THE FORECAST AREA FROM THE NORTHWEST TOWARD MORNING. WITH
ALL OF THIS IN MIND...HAVE TRIMMED BACK POPS OVERNIGHT AND
ESPECIALLY THIS EVENING...GRADUALLY INCREASING CHANCES AFTER
MIDNIGHT. MAINTAINED LIKELY POPS THURSDAY MORNING...WITH MCS
REMNANTS EXPECTED TO PERHAPS PRESENT THE GREATEST RAINFALL
PROBABILITY. 00Z SOUNDINGS UPSTREAM OF OUR FORECAST AREA DEPICT
PWATS IN THE 1.5-1.6 INCH RANGE SO STILL A LOCALLY HEAVY RAINFALL
THREAT FROM STRONGER CONVECTION ESPECIALLY DURING THE PRE-DAWN
THROUGH MID-MORNING THURSDAY PERIOD.
ALSO...WITH CLOUDS AND LIGHT WEST-SOUTHWEST FLOW BUMPED MIN TEMPS
JUST A BIT OVERNIGHT.
RATZER
&&
.PREV DISCUSSION...
320 PM CDT
MAIN FORECAST CONCERNS ARE WITH PERSISTENT CHANCES FOR SHOWERS AND
THUNDERSTORMS OVER THE NEXT SEVERAL DAYS...WITH SOME POTENTIAL FOR
STRONG/SEVERE STORMS BUT WITH HIGHER CONFIDENCE FOR HEAVY
RAINFALL. WITH CONFIDENCE STILL LOWER ON COVERAGE AND PLACEMENT
OF STORMS TONIGHT...HAVE NOT ISSUED A FLOOD WATCH AT THIS TIME
BUT DID ISSUE AN SPS TO RAISE AWARENESS FOR THIS POTENTIAL.
IN THE NEAR TERM...QUIETER CONDITIONS ONGOING THIS AFTERNOON WITH
THE BULK OF THE CWA DRY. LATEST RADAR IMAGERY DEPICTING STEADY
STREAM OF SHOWERS AND THUNDERSTORMS STILL MOVING SOUTHEAST THROUGH
EASTERN IOWA AND WEST CENTRAL ILLINOIS...BUT WITH COVERAGE AND
INTENSITY DIMINISHING. SHORT TERM GUIDANCE STILL TRYING TO BRING
PRECIP ACROSS NORTH/NORTHEAST ILLINOIS LATE THIS AFTERNOON INTO
THE EARLY EVENING BUT DONT REALLY AGREE. FEEL THAT CONDITIONS WILL
REMAIN DRY THROUGH EARLY THIS EVENING FOR MOST LOCATIONS WITH THE
EXCEPTION FOR AREAS ALONG AND SOUTHWEST OF LINE FROM OREGON TO
WATSEKA...WHERE STEERING FLOW COULD DRIFT A STRAY SHOWER OR
THUNDERSTORM BRIEFLY OVER THAT AREA. ELSEWHERE...BRIEF AND LIGHT
RETURNS CONTINUE TO SHOW ON RADAR OVER NORTHEAST ILLINOIS IN AND
AROUND WEAK CONVERGENCE ALONG LAKE BREEZE IN FAR SOUTHEAST
WISCONSIN AND FAR NORTHEAST ILLINOIS. A LACK OF ANY INHIBITION
THIS AFTERNOON AND THIS WEAK CONVERGENCE COULD ALLOW FOR CONTINUED
DEVELOPMENT OF THESE LIGHT SHOWERS THIS AFTERNOON.
TONIGHT...INCREASING CHANCES FOR SHOWERS/THUNDERSTORMS WILL OCCUR
THROUGHOUT THE NIGHT AS UPSTREAM UPPER LEVEL RIDGE CONTINUES TO
BUILD ACROSS THE REGION WITH THE RIDGE AXIS SHIFTING EAST TOWARDS
THE CWA...AND WHILE SURFACE WARM FRONT SITUATED OVER THE SOUTHERN
CWA LIFTS NORTH. UPSTREAM SHORTWAVE ENERGY NOTED ON CURRENT WATER
VAPOR IMAGERY WILL RIDE ALONG THIS RIDGE AND MOVE ACROSS THE CWA
TONIGHT INTO EARLY THURSDAY MORNING. MEANWHILE...STRENGTHENING LLJ
WILL BEGIN VEERING THIS EVENING AND THEN BE ORIENTED TOWARDS THE
CWA LATER IN THE NIGHT. THIS WILL ALL PROVIDE FOCUS FOR
THUNDERSTORM DEVELOPMENT OVERNIGHT ESPECIALLY AS WAA RAMPS UP WITH
THE VEERING/STRENGTHENING LLJ. WEAK TO MODERATE INSTABILITY AXIS
WILL BE IN PLACE TONIGHT WITH POTENTIAL FOR SOME STEEPER MID LAPSE
RATES...CURRENTLY OBSERVED JUST SOUTH OF THE CWA...TO LINGER
TONIGHT. CONFIDENCE IS NOT OVERLY GREAT WITH REGARDS TO THE
INTENSITY OF STORMS TONIGHT BUT WITH THE PREVIOUSLY MENTIONED
FORCING MECHANISMS COMING TOGETHER OVERHEAD TONIGHT...WOULD EXPECT
THE POSSIBILITY FOR AT LEAST AN ISOLATED STRONGER STORM TO PROVIDE
A HAIL/WIND THREAT. FEEL THAT THE BEST CHANCES FOR THIS
POSSIBILITY COULD OCCUR OVER THE SOUTH/SOUTHWEST HALF OF THE
CWA...WHERE THE STEEPER MID LEVEL LAPSE RATES WILL POSSIBLY RESIDE
PER CURRENT ANALYSIS AND SREF GUIDANCE.
A GROWING CONCERN WILL BE FOR THE POTENTIAL OF HEAVY RAINFALL AND
LOCALIZED FLOODING WITH THESE STORMS TONIGHT INTO EARLY THURSDAY.
GUIDANCE CONTINUES TO VARY WITH REGARD TO OVERALL COVERAGE AND
EXACT PLACEMENT OF BEST DEVELOPMENT TONIGHT...AND WITH MY
CONFIDENCE NOT THE GREATEST WITH REGARDS TO RESIDENCE TIME OF ANY
STORM. NONETHELESS...OBSERVED HIGH PWAT AXIS OF 1.5 TO 2 INCHES
CURRENTLY OBSERVED JUST TO THE SOUTHWEST OF THE CWA WILL SHIFT
NORTHEAST OVER THE CWA TONIGHT...AND WITH THIS HIGHEST AXIS
EXPECTED TO BE CENTERED OVERHEAD TONIGHT. WITH THESE HIGH PWATS IN
PLACE AND WITH SURFACE DEWPOINTS AROUND 70 DEG AND 850MB DEWPOINTS
APPROACHING 15-16C...ANY STORM WILL EASILY HAVE THE POTENTIAL TO
PRODUCE HEAVY DOWNPOURS. DESPITE THESE CONCERNS...I ONCE AGAIN
DONT HAVE THE GREATEST CONFIDENCE OF COVERAGE/PLACEMENT AND HAVE
DECIDED TO HOLD OFF ON ANY FLOOD WATCH AT THIS TIME. THIS WILL
NEED TO CONTINUE TO BE CLOSELY MONITORED THIS EVENING BUT IN THE
NEAR TERM HAVE DECIDED TO ISSUE AN SPS FOR THIS POSSIBILITY. STILL
THINK THAT WHAT OCCURRED JUST TO THE WEST/SOUTHWEST TODAY COULD
EASILY OCCUR TONIGHT INTO THURSDAY OVER THE CWA...ALTHOUGH WITH
THE POSSIBILITY FOR A SLIGHTLY DIFFERENT SETUP PROVIDING
BETTER/STRONGER THUNDERSTORM DEVELOPMENT.
ANY LINGERING STORMS THURSDAY MORNING WILL SHIFT EAST AND
NORTHEAST OF THE CWA THROUGH MID DAY WITH A POSSIBILITY FOR
CONTINUED HEAVY RAINFALL. THESE DEPARTING STORMS COULD ALLOW FOR
CLEARING SKIES AND THE ENVIRONMENT TO DESTABILIZE ONCE AGAIN
DURING MID DAY AND EARLY AFTERNOON...WITH THE POSSIBILITY FOR
THUNDERSTORMS TO REDEVELOP ALONG LIFTING FRONTAL BOUNDARY.
CLEARING WILL BE KEY WITH POTENTIAL FOR INTENSITY OF THESE STORMS
ON THURSDAY BUT WITH STRONG TO SEVERE STORMS POSSIBLE...ESPECIALLY
IF A GOOD AMOUNT OF HEATING COULD OCCUR. FOCUS FOR THUNDERSTORMS
WILL CONTINUE THURSDAY NIGHT AS WELL...WITH HIGH MOISTURE CONTENT
AIR STILL IN PLACE. THIS WILL ALSO CONTINUE CONCERNS FOR HEAVY
RAINFALL ACROSS THE AREA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* CHANCE FOR TSRA OVERNIGHT INTO THURSDAY MORNING.
KJB
//DISCUSSION...UPDATED 00Z...
THE MAIN AVIATION WEATHER CONCERNS THROUGH THE PERIOD WILL BE
CHANCES AND TIMING OF CONVECTIVE ACTIVITY.
UNFORTUNATELY CONFIDENCE IN TIMING OF THUNDER AT THE TERMINALS
REMAINS LOW AT THIS TIME. A WARM FRONT IS EXPECTED TO LIFT NORTHWARD
ACROSS THE AREA BY THURSDAY...WITH A WARM...HUMID AND UNSTABLE
ATMOSPHERE EXPECTED. IT APPEARS THE MAIN FOCUS FOR THUNDERSTORMS
TONIGHT WILL BE ACROSS SOUTHERN MN AND PORTIONS OF IOWA ALONG THE
BETTER FOCUS OF A LOW LEVEL JET. HOWEVER...ADDITIONAL SCATTERED
SHOWERS AND STORMS COULD ALSO DEVELOP TONIGHT ALONG AND AHEAD OF THE
WARM FRONTAL BOUNDARY...ACROSS PORTIONS OF NORTHERN ILLINOIS. THE
MAIN QUESTION WITH THESE STORMS ARE HOW FAR NORTHEASTWARD THEY REACH
LATER TONIGHT...AND HENCE IF THEY WILL DIRECTLY IMPACT THE
TERMINALS. THE THREAT FOR THUNDERSTORMS WILL CONTINUE DURING THE
MORNING THURSDAY...WITH THE POTENTIAL FOR REMNANTS OF THE SOUTHERN
MN CONVECTION MOVING SOUTHEASTWARD ACROSS THE AREA AFTER
DAYBREAK.
WITH OVERALL CONFIDENCE REMAINING LOW TO MODERATE...I HAVE MADE
LITTLE CHANGES TO THE GOING FORECAST.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW-MEDIUM WITH TSRA LATE TONIGHT INTO THURSDAY MORNING.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...PERIODIC CHANCES FOR TSRA.
KJB
&&
.MARINE...
158 PM CDT
FAIRLY LIGHT WIND REGIME IS EXPECTED THROUGH THE WEEKEND WITH WEAK
PRESSURE GRADIENT EXPECTED WITH HIGH PRESSURE OVER THE ST LAWRENCE
VALLEYS REGION AND A TROUGH OF LOW PRESSURE OVER THE NORTHERN AND
CENTRAL PLAINS. A QUASI-STATIONARY WARM FRONT WILL EXTEND EAST FROM
THE LOW INTO THE LOWER GREAT LAKES REGION...WITH THE POSITION OF THE
WARM FRONT LIKELY BEING MODULATED AT TIMES BY CONVECTIVE COMPLEXES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
125 PM CDT TUE AUG 19 2014
.DISCUSSION...
1114 AM CDT
MAIN CONCERNS/CHALLENGES FOR MORNING UPDATE WERE MONITORING
SHOWER/THUNDERSTORM CHANCES THIS MORNING THROUGH THE AFTERNOON.
LATEST RADAR IMAGERY SHOWING THUNDERSTORM COMPLEX WHICH HAS MOVED
THROUGH NORTHERN MISSOURI AND WEST CENTRAL ILLINOIS THIS
MORNING...CONTINUING EAST AND CURRENTLY IMPACTING AREAS FROM LA
SALLE TO PONTIAC. EXPECT THIS COMPLEX TO CONTINUE EAST THROUGH THE
EARLY AFTERNOON...WITH THUNDERSTORMS LIKELY TO BUILD FURTHER TO
THE NORTHEAST TOWARDS THE CHICAGO METRO AREA OVER THE ONE TO TWO
HOURS...ALONG APPROACHING SURFACE TROUGH AND FRONT TO THE
NORTHWEST. FEEL FAIRLY CONFIDENT WITH THIS POSSIBILITY AS THIS
MID LEVEL WAVE AND SURFACE TROUGH/FRONT WILL MOVE THROUGH AN
ENVIRONMENT WITH LITTLE TO NO CIN AND MODERATE INSTABILITY.
CONFIDENCE IS LOWER WITH REGARD TO INTENSITY OF THESE STORMS AS
LARGE CLOUD SHIELD HAS LIMITED STEEPNESS OF LOW LEVEL LAPSE
RATES...AND WITH WESTERLIES/BULK SHEAR VALUES REMAINING ON THE
LOWER SIDE. COULD SEE THE STRONGEST DEVELOPMENT OCCURRING OVER
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA AS THIS BROKEN LINE OF
THUNDERSTORMS PUSHES EAST/SOUTHEAST THROUGH MID AFTERNOON...WITH
AN ISOLATED SEVERE THREAT STILL POSSIBLE. HIGH WIND GUSTS WOULD
BE THE MAIN THREAT...AS WELL AS HEAVY RAINFALL. SURFACE DEWPOINTS
RIGHT AROUND 70 DEG WITH AXIS OF HIGHEST PWATS RIGHT OVER THE
SOUTHEAST TWO THIRDS OF THE CWA SHOULD ALLOW FOR EFFICIENT RAIN
PRODUCERS TODAY...AND HAVE MADE MENTION OF THIS POTENTIAL FOR
LOCALLY HEAVY RAINFALL IN THE HWO.
RODRIGUEZ
//PREV DISCUSSION...
336 AM CDT
SHORT TERM...THROUGH TUESDAY NIGHT...
FOR THE REMAINDER OF THE OVERNIGHT HOURS...THE MAIN FOCUS WILL BE
THE PROGRESSION OF THUNDERSTORMS ALONG A WEAK COLD FRONT MOVING
THROUGH SRN WI/NERN IA AND PUSHING INTO NRN IL. THE MAIN SHORTWAVE
ASSOCIATED WITH THE ACTIVITY IS MOVING QUICKLY OVER ERN WI AND CNTRL
LAKE MICHIGAN. AS THE SHORTWAVE RACES RATHER QUICKLY TO THE
EAST...THE LINE OF THUNDERSTORMS IS TAKING ON A MORE EAST-WEST
ORIENTATION ALONG THE WISCONSIN BORDER...BUT IS SAGGING INTO
WINNEBAGO AND BOONE COUNTIES. SOME STRONG THUNDERSTORMS ALONG THIS
PORTION OF THE FRONT HAVE THE POTENTIAL TO PRODUCE SOME SMALL HAIL
AND LOCALIZED STRONGER WIND GUSTS. THERE IS STILL SOME CONCERN
ABOUT HOW FAR SOUTH THE ACTIVITY WILL REACH. CURRENTLY ANTICIPATE
THAT THE GREATEST THUNDERSTORM COVERAGE SHOULD BE OVER THE NORTHERN
TIER COUNTIES ALONG THE WISCONSIN BORDER. HOWEVER...THERE IS STILL
SOME SWLY FLOW ALOFT WITH WITH 850MB WINDS ARND 30KT...WHILE SFC
FLOW IS LIGHT AND GENERALLY SOUTHERLY. THERE IS PLENTY OF LOW
LEVEL MOISTURE IN PLACE AND WITH AT LEAST MODEST ISENTROPIC LIFT IN
THE WARM SECTOR WHICH COULD AT LEAST GENERATE SCT SHRA/TSRA. THE
LATEST HIGH RES GUIDANCE IS INDICATING A DIMINISHING TREND TO THE
CONVECTION ALONG THE SRN PORTION OF THE FRONT AS IT MOVES THROUGH
THE AREA THIS MORNING...SO HAVE BACKED OFF POPS TO SLIGHT
CHANCE...BUT WITH DAYTIME WARMING...THERE SHOULD BE AN UPTICK IN THE
CONVECTIVE ACTIVITY AD THE FRONT PUSHES THROUGH THE SRN PORTIONS OF
THE CHICAGO METRO AREA AND INTO ECNTRL IL AND NWRN INDIANA. PORTIONS
OF THE CWA. WITH INCREASING SLWY DEVELOPING WITH THE APPROACH OF
THE COLD FRONT AND VEERING TO WLY FOLLOWING THE FROPA...NO LAKE
BREEZE DEVELOPMENT IS EXPECTED TODAY AND THE WARM AIR SHOULD HAVE NO
TROUBLE REACHING RIGHT UP TO THE LAKEFRONT...WITH TEMPS IN THE LOWER
TO MIDDLE 80S EXPECTED FOR THE ENTIRE CWA.
ANY RESIDUAL PCPN ASSOCIATED WITH THE PASSING COLD FRONT SHOULD PUSH
TO THE EAST OF THE CWA BY LATE THIS EVENING. WEAK HIGH PRESSURE
SHOULD BUILD IN BEHIND THE FRONT WEDNESDAY EVENING AND OVERNIGHT.
WITH GENERALLY WLY FLOW BEHIND THE FRONT...AND NO SGFNT DRY AIR
UPSTREAM...THE LOW LEVELS SHOULD REMAIN VERY MOIST...SO FOG
DEVELOPMENT LATE TUESDAY NIGHT AND POSSIBLY INTO WEDNESDAY MORNING
IS A DISTINCT POSSIBILITY.
KREIN
WEDNESDAY THROUGH THURSDAY...
MAIN FEATURE IN THE MEDIUM TERM WILL BE THE DEPARTING MID-LVL VORT
FROM THE GREAT LAKES...STEADILY WEAKENING AND EJECTING EAST.
MEANWHILE A DEVELOPING 500MB RIDGE WILL TAKE SHAPE ACROSS THE
PLAINS...THEN LIFT NORTHEAST THUR. THE STALLED FRONTAL BOUNDARY WILL
REMAIN SOUTH OF THE FORECAST AREA THRU WED THEN AS THE RIDGE
STEADILY BUILDS AND EXPANDS NORTH WARM AIR ADVECTION WILL LIFT THE
BOUNDARY NORTH. THIS WILL LIKELY FEATURE MOISTENING LLVLS WITH
DECENT ISENTROPIC LIFT ALONG THE BOUNDARY...TO SUPPORT INCREASING
POPS LATE WED FROM SOUTH TO NORTH. WHILE IT APPEARS FAVORABLE FOR A
CHANNEL OF LIKELY POPS LATE WED-EARLY THUR...THERE IS SOME CONCERN
THAT WE COULD QUICKLY BECOME CAPPED WITH A STRONG PUSH OF VERY WARM
AIR ALOFT. SOME GUIDANCE IS SUGGESTING AFT 00Z 850MB THERMAL TEMPS
RISE TO ARND 19-20 DEG C...WHICH COULD BE ENOUGH TO LIMIT
COVERAGE/INTENSITY. HOWEVER IF THIS ENDS UP BEING SLIGHTLY COOLER
ANY PRECIP THAT DOES DEVELOP COULD EASILY PRODUCE LOCALLY HEAVY
RAINFALL...AS PWAT VALUES ARE EXPECTED TO RISE TO NEAR 1.7-2.0"
OVERNIGHT. TEMPS WED WILL PUSH INTO THE MID 80S...HOWEVER IT IS
PLAUSIBLE THAT A WEAK LK BREEZE COULD FORM EARLY IN THE AFTN AND
KEEP THE NEARSHORE AREAS COOLER.
WITH WARM AIR STEADILY ADVECTING NORTH INTO THE FORECAST
AREA...EXPECT TEMPS TO REMAIN MILD OVERNIGHT IN THE MID/UPR 60S. IF
CLOUDS AND PRECIP ARRIVE EARLIER WED EVE...THEN TEMPS MAY NOT DIP
BELOW 70.
THUR WILL FEATURE STEADILY RISING MID-LVL HEIGHTS AS THE ROBUST
RIDGE ESTABLISHES ITSELF ACROSS A BULK OF OF THE REGION. THIS POSES
CHALLENGES WITH PRECIP FOR THUR. GUIDANCE CONTINUES TO FAVOR A
SHORTWAVE LIFTING NORTHEAST INTO THE UPPER MIDWEST WITH BETTER
MID-LVL VORTICITY THEN SLIDING EAST ALONG THE NORTHERN PERIPHERY OF
THE RIDGE...BEFORE DIVING SOUTHEAST TOWARDS THE EASTERN GREAT LAKES.
THIS COUPLED WITH VERY WARM 850MB TEMPS NEARING 20 DEG C MAY RESULT
IN A CAPPED ENVIRONMENT. CONFIDENCE IS NOT YET STRONG ENOUGH TO
FURTHER REDUCE POPS THUR AFTN. DEPENDING ON CLOUDS/PRECIP THUR WILL
STEER HOW WARM SFC TEMPS BECOME. GUIDANCE CONTINUES TO POINT TOWARDS
MID/UPR 80S. DEW PTS WILL BE PUSHING INTO THE LOW 70S...WHICH THE
COMBINATION OF TEMP/DEW PT COULD BE SUPPORTIVE OF HEAT INDEX VALUES
NEARING THE MID 90S.
CONCERN REMAINS FOR THUR NGT ON POPS...BUT MORE IMPORTANTLY ON
POTENTIAL FOR HEAVY RAINFALL. PWAT VALUES CONTINUE TO HOVER ARND 2"
WITH VERY WARM DEW PTS BETWEEN 72-74 DEG. WITH THE LACK OF A STRONG
WIND FIELD...STORMS COULD BE SLOW MOVING AND EASILY PRODUCE LOCALLY
HEAVY RAINFALL. OVERNIGHT LOWS MAY NOT DIP BELOW THE MID/UPR
70S...WHICH SETS THE STAGE FOR A POTENTIALLY HOT/HUMID DAY FRI.
FRIDAY THROUGH EARLY NEXT WEEK...
MID-LVL RIDGING CONTINUES TO BE PROGGED FOR THE FRI-SUN
PERIODS...WHICH SETS THE STAGE FOR POTENTIALLY A VERY WARM STRETCH
ACROSS THE REGION WITH NUMEROUS AREAS REACHING 90 DEG IN THIS
TIMEFRAME. GUIDANCE CONTINUES TO FAVOR A HIGH PROBABILITY THAT DEW
PTS WILL EASILY REMAIN IN THE 72-74 DEG RANGE FRI/SAT...WHICH
COUPLED WITH TEMPS ARND 90 COULD EASILY PRODUCE 100 DEG HEAT INDEX
READINGS. THE CURRENT ECMWF SOLUTION PAINTS AN EVEN WARMER THERMAL
RIDGE AT 850MB FOR SUN AT 23-25 DEG C. CLOUDS/PRECIP WILL LIKELY
STEER HOW WARM SUN BECOMES.
THEN ENSEMBLES CONTINUE TO DEMONSTRATE SOME CONSISTENCY THAT THE
MID-LVL RIDGE WILL WEAKEN EARLY NEXT WEEK WITH A RETURN TO TROUGHING
ACROSS THE MIDDLE OF THE CONUS. CURRENT GUIDANCE SUGGESTS A FRONTAL
BOUNDARY WILL ARRIVE IN THE MON/TUE TIMEFRAME AND BRING TEMPS BACK
TO SEASONAL OR SLIGHTLY SUB-SEASONAL CONDS FOR THE MIDDLE OF NEXT
WEEK.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* ISOL SHRA/TSRA POSSIBLE THROUGH MID AFTERNOON.
* WESTERLY WINDS GUSTING TO AROUND 20 KT THROUGH EARLY EVENING.
* POTENTIAL FOR MVFR VIS IN BR LATE TONIGHT INTO WED MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 18Z...
LATEST RADAR IMAGERY SHOWING AREA OF THUNDERSTORMS EXITING TO THE
EAST OF THE TERMINALS...BUT WITH GYY THE ONLY TERMINAL BEING
IMPACTED AT THIS TIME. THIS WILL CONTINUE EAST OVER THE NEXT HOUR
WITH GENERALLY DRY CONDITIONS THEN EXPECTED OVER THE NEXT SEVERAL
HOURS. ISOL TO WIDELY SCATTERED SHOWERS ARE STILL DEVELOPING OVER
FAR NORTHERN ILLINOIS AND SOUTHERN WISCONSIN...OUT AHEAD OF FRONT
STRETCHED FROM SOUTHERN WISCONSIN TO EASTERN IOWA. THIS WILL
LIKELY CONTINUE INTO THE AFTERNOON AS THIS FRONT DROPS TO THE
SOUTHEAST...BUT EXPECT IT TO REMAIN LIMITED IN COVERAGE AS BETTER
LIFT ALOFT IS LOST. ONLY HAVE VCSH MENTIONED DUE TO ANTICIPATED
COVERAGE...BUT WILL NEED TO CONTINUE MONITORING THE POTENTIAL FOR
A STRAY SHOWER AND EVEN AN OUTSIDE POSSIBILITY FOR A BRIEF/ISOL
STORM TO MOVE OVER THE TERMINALS. CEILINGS STILL HOVERING AROUND
MVFR/VFR...BUT WITH VFR CEILINGS EXPECTED THIS AFTERNOON THROUGH
THE REST OF THE FORECAST PERIOD. FAIRLY MOIST CONDITIONS LINGERING
TONIGHT COULD ALLOW FOR FOG DEVELOPMENT...AND HAVE CONTINUED
MENTION OF THIS IN THE TAF.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM HIGH CONFIDENCE WITH ISOL SHRA/TSRA DEVELOPING AROUND THE
TERMINALS THIS AFTERNOON...LOW CONFIDENCE WITH THIS IMPACTING
THE TERMINALS.
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
* MEDIUM CONFIDENCE WITH MVFR VIS OCCURRING LATE TONIGHT INTO
WEDNESDAY MORNING.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT THROUGH SUNDAY...PERIODIC CHANCES FOR TSRA AND
OCNL REDUCED CIGS/VIS.
SUNDAY NIGHT THROUGH MONDAY...VFR. WX NIL.
&&
.MARINE...
316 AM CDT
AN AREA OF LOW PRESSURE OVER CENTRAL WISC WILL CONTINUE TO DRIFT
NORTHEAST ACROSS THE NORTHERN PORTION OF THE LAKE MIDDAY...THEN
CONTINUE TO SLIDE EAST AND WEAKEN WEDNESDAY AFTERNOON ACROSS
SOUTHEAST ONTARIO. THE GRADIENT IS EXPECTED TO TIGHTEN SLIGHTLY
FROM THE SOUTH...WITH WINDS INCREASING THIS MORNING TO ARND 15 TO
25KT. THEN AS THE LOW SLIDES EAST WINDS WILL BECOME WEST AND
DIMINISH TO ARND 10 TO 20 KT LATE TONIGHT. WAVES SHUD BE ABLE TO
BRIEFLY BUILD ACROSS THE LAKE TO ARND 2-4FT...THEN WITH A LIGHTER
GRADIENT ARRIVING WED WAVES WILL SUBSIDE TO ARND 2 FT OR LESS. IN
THE DEPARTING SFC LOW WILL BE A MUCH WEAKER GRADIENT...WITH WINDS
GENERALLY LIGHT FROM THE NORTH ARND 5 TO 10 KT ACROSS THE NORTHERN
HALF OF THE LAKE AND AROUND 10 KT FROM THE SOUTH FOR THE SOUTHERN
HALF OF THE LAKE. A WARM FRONTAL BOUNDARY WILL LIFT NORTH ACROSS
THE SOUTHERN PORTION OF THE LAKE EARLY THUR...WITH MUCH WARMER AIR
LIFTING OVER THE LAKE. AT THIS TIME FEEL THAT FOG MAY NOT
DEVELOP...BUT COULD SEE SOME HAZY CONDITIONS DEVELOP LATE IN THE
WEEK. SOUTH/SOUTHEAST WINDS FOR THE WEEKEND. THE UPPER FLOW
PATTERN DOES LOOK TO SHIFT SUNDAY OR MONDAY BRINGING A COLD FRONT
ACROSS THE LAKE WITH A SHIFT TO NORTHERLY WINDS WHICH MAY BE
RATHER BREEZY EARLY NEXT WEEK.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1244 PM CDT Tue Aug 19 2014
.UPDATE...
ISSUED AT 923 CDT TUE AUG 19 2014
Area of showers and thunderstorms associated with an upper-level
wave is currently crossing the Mississippi River into west-central
Illinois. 1417z radar imagery shows leading edge of precip extending
from Galesburg...to Rushville...to Bowling Green Missouri. Based
on timing tools, showers/thunder will arrive along the I-55
corridor by midday. HRRR and other high-res models generally show
the precip area weakening as it pushes eastward through the
morning, then potentially re-developing across east-central
Illinois later this afternoon. Made some adjustments to hourly
PoPs today, mainly to increase to categorical along/west of I-55
during the morning. Once the wave passes, rain chances will come
to an end across the Illinois River Valley by mid to late
afternoon, followed by a return to partly to mostly sunny skies.
Further east, rain chances will linger throughout the day before
coming to an end by evening.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 336 AM CDT TUE AUG 19 2014
Short term models have trended slower with the front and precip that
is currently supposed to be moving into the area. But will still
have chance of precip starting in the northwest parts of the cwa
this morning. Then will progress the pcpn chances southeastward
across the cwa during the day. By this evening, most of the pcpn
will be in the eastern two thirds of the area with the highest pops
in the southeast. By overnight, the pcpn should have moved southeast
of the area so most of the area should be dry overnight, though will
keep a slight chance of pops in the southeast after midnight. Could
be some additional pcpn in the southwest late tonight, but models
keep most of pcpn west of the area through 12z.
Temps will begin the slow warming tomorrow, and am expecting mid to
upper 80s throughout the area today.
&&
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 347 AM CDT TUE AUG 19 2014
Models still pretty consistent with the development and lift of a
boundary through the Midwest on Wednesday. Boundary will have little
reflection at the sfc with very weak flow/weak wind shift, and
thermal gradient is better represented in the mid levels. Boundary
will provide a weak focus for waves moving through the region as the
boundary lifts to the NE through the area for Wed/Wed night. Though
Wed is lacking signif pop for now, the timing of the progression is
better for early evening and into the overnight on Wednesday
night/shifting to the northeast for Thurs. Position of the boundary
or the remnants thereof will be where the majority of the precip
chances will be...increasing to the north, particularly north of
Interstate 74 from Thursday to Saturday. Ample sfc based instability
in the form of hot and humid conditions as the ridge over the
southwest opens and spreads signif heat into the Midwest. Models
have also shown consistency with 850 mb temps in the 19-25C range
from Wednesday through Sunday. This will drive the temps into the
upper 80s/lower 90s with heat indices in the upper 90s/approaching
100F. A far more summer-like pattern than much of the season so far,
and well above normal for this time of year...with breaks from the
heat provided by any thunderstorms that may have the chance to form
from more diurnal instability with any frontal forcing further to
the north. Into the extended, day 7/just into day 8, models diverge
in solutions with major difference in breaking down the upper ridge
for the Midwest.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1244 PM CDT TUE AUG 19 2014
17z surface analysis shows cold front across eastern Iowa
approaching the Mississippi River. Earlier convection that pushed
into the Illinois River Valley ahead of the front continues to
diminish as it tracks toward the I-57 corridor. Based on latest
satellite/radar trends, it appears chances for additional
convection at KPIA are slim to none, so have gone with a dry
forecast there. Further southeast at the remaining terminals, will
carry either VCTS or a TEMPO group for thunder this afternoon.
Atmosphere has been temporarily stabilized due to clouds/showers
this morning, but as skies partially clear, think scattered
showers/storms will develop east of the Illinois River through the
afternoon. Any convection that fires up will push into Indiana by
early evening, followed by clearing skies tonight. Given clear
skies and light winds, think areas of fog will once again develop.
Have dropped visbys lowest at KPIA where quite a bit of rain fell
earlier, but have gone with 2-3 miles everywhere between 07z and
14z. After that, mostly clear skies with a light W/SW wind will
prevail by Wednesday morning.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...AUTEN
LONG TERM...HJS
AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1113 AM CDT TUE AUG 19 2014
.DISCUSSION...
336 AM CDT
SHORT TERM...THROUGH TUESDAY NIGHT...
FOR THE REMAINDER OF THE OVERNIGHT HOURS...THE MAIN FOCUS WILL BE
THE PROGRESSION OF THUNDERSTORMS ALONG A WEAK COLD FRONT MOVING
THROUGH SRN WI/NERN IA AND PUSHING INTO NRN IL. THE MAIN SHORTWAVE
ASSOCIATED WITH THE ACTIVITY IS MOVING QUICKLY OVER ERN WI AND CNTRL
LAKE MICHIGAN. AS THE SHORTWAVE RACES RATHER QUICKLY TO THE
EAST...THE LINE OF THUNDERSTORMS IS TAKING ON A MORE EAST-WEST
ORIENTATION ALONG THE WISCONSIN BORDER...BUT IS SAGGING INTO
WINNEBAGO AND BOONE COUNTIES. SOME STRONG THUNDERSTORMS ALONG THIS
PORTION OF THE FRONT HAVE THE POTENTIAL TO PRODUCE SOME SMALL HAIL
AND LOCALIZED STRONGER WIND GUSTS. THERE IS STILL SOME CONCERN
ABOUT HOW FAR SOUTH THE ACTIVITY WILL REACH. CURRENTLY ANTICIPATE
THAT THE GREATEST THUNDERSTORM COVERAGE SHOULD BE OVER THE NORTHERN
TIER COUNTIES ALONG THE WISCONSIN BORDER. HOWEVER...THERE IS STILL
SOME SWLY FLOW ALOFT WITH WITH 850MB WINDS ARND 30KT...WHILE SFC
FLOW IS LIGHT AND GENERALLY SOUTHERLY. THERE IS PLENTY OF LOW
LEVEL MOISTURE IN PLACE AND WITH AT LEAST MODEST ISENTROPIC LIFT IN
THE WARM SECTOR WHICH COULD AT LEAST GENERATE SCT SHRA/TSRA. THE
LATEST HIGH RES GUIDANCE IS INDICATING A DIMINISHING TREND TO THE
CONVECTION ALONG THE SRN PORTION OF THE FRONT AS IT MOVES THROUGH
THE AREA THIS MORNING...SO HAVE BACKED OFF POPS TO SLIGHT
CHANCE...BUT WITH DAYTIME WARMING...THERE SHOULD BE AN UPTICK IN THE
CONVECTIVE ACTIVITY AD THE FRONT PUSHES THROUGH THE SRN PORTIONS OF
THE CHICAGO METRO AREA AND INTO ECNTRL IL AND NWRN INDIANA. PORTIONS
OF THE CWA. WITH INCREASING SLWY DEVELOPING WITH THE APPROACH OF
THE COLD FRONT AND VEERING TO WLY FOLLOWING THE FROPA...NO LAKE
BREEZE DEVELOPMENT IS EXPECTED TODAY AND THE WARM AIR SHOULD HAVE NO
TROUBLE REACHING RIGHT UP TO THE LAKEFRONT...WITH TEMPS IN THE LOWER
TO MIDDLE 80S EXPECTED FOR THE ENTIRE CWA.
ANY RESIDUAL PCPN ASSOCIATED WITH THE PASSING COLD FRONT SHOULD PUSH
TO THE EAST OF THE CWA BY LATE THIS EVENING. WEAK HIGH PRESSURE
SHOULD BUILD IN BEHIND THE FRONT WEDNESDAY EVENING AND OVERNIGHT.
WITH GENERALLY WLY FLOW BEHIND THE FRONT...AND NO SGFNT DRY AIR
UPSTREAM...THE LOW LEVELS SHOULD REMAIN VERY MOIST...SO FOG
DEVELOPMENT LATE TUESDAY NIGHT AND POSSIBLY INTO WEDNESDAY MORNING
IS A DISTINCT POSSIBILITY.
KREIN
WEDNESDAY THROUGH THURSDAY...
MAIN FEATURE IN THE MEDIUM TERM WILL BE THE DEPARTING MID-LVL VORT
FROM THE GREAT LAKES...STEADILY WEAKENING AND EJECTING EAST.
MEANWHILE A DEVELOPING 500MB RIDGE WILL TAKE SHAPE ACROSS THE
PLAINS...THEN LIFT NORTHEAST THUR. THE STALLED FRONTAL BOUNDARY WILL
REMAIN SOUTH OF THE FORECAST AREA THRU WED THEN AS THE RIDGE
STEADILY BUILDS AND EXPANDS NORTH WARM AIR ADVECTION WILL LIFT THE
BOUNDARY NORTH. THIS WILL LIKELY FEATURE MOISTENING LLVLS WITH
DECENT ISENTROPIC LIFT ALONG THE BOUNDARY...TO SUPPORT INCREASING
POPS LATE WED FROM SOUTH TO NORTH. WHILE IT APPEARS FAVORABLE FOR A
CHANNEL OF LIKELY POPS LATE WED-EARLY THUR...THERE IS SOME CONCERN
THAT WE COULD QUICKLY BECOME CAPPED WITH A STRONG PUSH OF VERY WARM
AIR ALOFT. SOME GUIDANCE IS SUGGESTING AFT 00Z 850MB THERMAL TEMPS
RISE TO ARND 19-20 DEG C...WHICH COULD BE ENOUGH TO LIMIT
COVERAGE/INTENSITY. HOWEVER IF THIS ENDS UP BEING SLIGHTLY COOLER
ANY PRECIP THAT DOES DEVELOP COULD EASILY PRODUCE LOCALLY HEAVY
RAINFALL...AS PWAT VALUES ARE EXPECTED TO RISE TO NEAR 1.7-2.0"
OVERNIGHT. TEMPS WED WILL PUSH INTO THE MID 80S...HOWEVER IT IS
PLAUSIBLE THAT A WEAK LK BREEZE COULD FORM EARLY IN THE AFTN AND
KEEP THE NEARSHORE AREAS COOLER.
WITH WARM AIR STEADILY ADVECTING NORTH INTO THE FORECAST
AREA...EXPECT TEMPS TO REMAIN MILD OVERNIGHT IN THE MID/UPR 60S. IF
CLOUDS AND PRECIP ARRIVE EARLIER WED EVE...THEN TEMPS MAY NOT DIP
BELOW 70.
THUR WILL FEATURE STEADILY RISING MID-LVL HEIGHTS AS THE ROBUST
RIDGE ESTABLISHES ITSELF ACROSS A BULK OF OF THE REGION. THIS POSES
CHALLENGES WITH PRECIP FOR THUR. GUIDANCE CONTINUES TO FAVOR A
SHORTWAVE LIFTING NORTHEAST INTO THE UPPER MIDWEST WITH BETTER
MID-LVL VORTICITY THEN SLIDING EAST ALONG THE NORTHERN PERIPHERY OF
THE RIDGE...BEFORE DIVING SOUTHEAST TOWARDS THE EASTERN GREAT LAKES.
THIS COUPLED WITH VERY WARM 850MB TEMPS NEARING 20 DEG C MAY RESULT
IN A CAPPED ENVIRONMENT. CONFIDENCE IS NOT YET STRONG ENOUGH TO
FURTHER REDUCE POPS THUR AFTN. DEPENDING ON CLOUDS/PRECIP THUR WILL
STEER HOW WARM SFC TEMPS BECOME. GUIDANCE CONTINUES TO POINT TOWARDS
MID/UPR 80S. DEW PTS WILL BE PUSHING INTO THE LOW 70S...WHICH THE
COMBINATION OF TEMP/DEW PT COULD BE SUPPORTIVE OF HEAT INDEX VALUES
NEARING THE MID 90S.
CONCERN REMAINS FOR THUR NGT ON POPS...BUT MORE IMPORTANTLY ON
POTENTIAL FOR HEAVY RAINFALL. PWAT VALUES CONTINUE TO HOVER ARND 2"
WITH VERY WARM DEW PTS BETWEEN 72-74 DEG. WITH THE LACK OF A STRONG
WIND FIELD...STORMS COULD BE SLOW MOVING AND EASILY PRODUCE LOCALLY
HEAVY RAINFALL. OVERNIGHT LOWS MAY NOT DIP BELOW THE MID/UPR
70S...WHICH SETS THE STAGE FOR A POTENTIALLY HOT/HUMID DAY FRI.
FRIDAY THROUGH EARLY NEXT WEEK...
MID-LVL RIDGING CONTINUES TO BE PROGGED FOR THE FRI-SUN
PERIODS...WHICH SETS THE STAGE FOR POTENTIALLY A VERY WARM STRETCH
ACROSS THE REGION WITH NUMEROUS AREAS REACHING 90 DEG IN THIS
TIMEFRAME. GUIDANCE CONTINUES TO FAVOR A HIGH PROBABILITY THAT DEW
PTS WILL EASILY REMAIN IN THE 72-74 DEG RANGE FRI/SAT...WHICH
COUPLED WITH TEMPS ARND 90 COULD EASILY PRODUCE 100 DEG HEAT INDEX
READINGS. THE CURRENT ECMWF SOLUTION PAINTS AN EVEN WARMER THERMAL
RIDGE AT 850MB FOR SUN AT 23-25 DEG C. CLOUDS/PRECIP WILL LIKELY
STEER HOW WARM SUN BECOMES.
THEN ENSEMBLES CONTINUE TO DEMONSTRATE SOME CONSISTENCY THAT THE
MID-LVL RIDGE WILL WEAKEN EARLY NEXT WEEK WITH A RETURN TO TROUGHING
ACROSS THE MIDDLE OF THE CONUS. CURRENT GUIDANCE SUGGESTS A FRONTAL
BOUNDARY WILL ARRIVE IN THE MON/TUE TIMEFRAME AND BRING TEMPS BACK
TO SEASONAL OR SLIGHTLY SUB-SEASONAL CONDS FOR THE MIDDLE OF NEXT
WEEK.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* CHANCE FOR SHRA/TSRA MID DAY THROUGH EARLY AFTERNOON...WITH
BETTER CHANCES FOR MDW.
* SWLY-WLY WINDS GUSTING TO 20 KT THROUGH EARLY EVENING.
* POTENTIAL FOR MVFR VIS IN BR LATE TONIGHT INTO WED MORNING.
KREIN/RODRIGUEZ
//DISCUSSION...UPDATED 12Z...
THE UPPER LEVEL DISTURBANCE THAT BROUGHT THE SHRA/TSRA TO SRN WI
AND NRN IL HAS MOVED INTO LOWER MICHIGAN AND THAT PCPN HAS MOVED
AWAY FROM THE REGION. THE TRAILING COLD FRONT IS LAGGING SW ACROSS
THE AREA FROM NEAR UGN INTO SERN IA AT 12Z. SCT SHRA/TSRA HAVE
DEVELOPED ALONG THE FRONT...MOVING THROUGH THE ORD AREA BTWN
1100-1130Z. THIS ACTIVITY IS ALSO DISSIPATING AS IT MOVES EWD AND
EXPECT THAT THE TERMINALS...WITH THE EXCEPTION OF GYY SHOULD BE
DRY FOR THE REMAINDER OF THE MORNING. THERE IS STILL SOME CONCERN
THAT ADDITIONAL TSRA WILL IGNITE ALONG THE BOUNDARY BY LATE
MORNING OR EARLY AFTERNOON AS IT MOVES INTO NWRN IN-ECNTRL IL.
DIURNAL WARMING AND WEAK SFC CONVERGENCE SHOULD HELP ORGANIZE THE
DEVELOPMENT...BUT ANTICIPATE THAT IT SHOULD BE TO THE EAST OF THE
TERMINALS...WITH THE POSSIBLE EXCEPTION OF GYY BY THE TIME THE
ACTIVITY REDEVELOPS. AS FOR WINDS...LIGHT SWLY WINDS WILL
CONTINUE IN ADVANCE OF THE WEAK COLD FRONT...AND INCREASE THROUGH
THE MORNING AS THE SFC PRESSURE GRADIENT STRENGTHENS. BY LATE
MORNING...SWLY WINDS SHOULD INCREASE TO 10-15KT WITH OCNL GUSTS OF
20KT PERSISTING THROUGH EARLY EVENING WHILE GRADUALLY VEERING TO
WESTERLY BY LATE AFTERNOON UNTIL AROUND SUNSET. HIGH PRESSURE
BUILDING IN OVERNIGHT TONIGHT SHOULD BRING DECREASING CLOUD COVER
AND DIMINISHING WINDS. WITH AMPLE RESIDUAL MOISTURE EXPECT AT
LEAST PATCHY FOG TO DEVELOP AFTER MIDNIGHT. THERE IS THE POTENTIAL
FOR VIS TO DROP TO IFR...BUT THERE IS A CHANCE THAT THERE COULD BE
SOME RESIDUAL CLOUD COVER FROM CONVECTIVE ACTIVITY CURRENTLY
MOVING THROUGH MISSOURI COULD LIMIT THE VIS DROPPING...SO WILL
ONLY GO 3-4SM BR FOR NOW.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* LOW MEDIUM CONFIDENCE FOR TSRA/SHRA TO IMPACT ORD...MEDIUM HIGH
CONFIDENCE FOR TSRA/SHRA TO IMPACT MDW MID DAY THROUGH EARLY
AFTERNOON.
* MEDIUM TO HIGH CONFIDENCE IN WIND SPEED AND DIRECTION.
* MEDIUM CONFIDENCE IN MVFR VIS OCCURRING LATE TONIGHT INTO
WEDNESDAY MORNING. LOW CONFIDENCE IN CHANCES FOR IFR VIS.
KREIN/RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT THROUGH SUNDAY...PERIODIC CHANCES FOR TSRA AND
OCNL REDUCED CIGS/VIS.
SUNDAY NIGHT THROUGH MONDAY...VFR. WX NIL.
&&
.MARINE...
316 AM CDT
AN AREA OF LOW PRESSURE OVER CENTRAL WISC WILL CONTINUE TO DRIFT
NORTHEAST ACROSS THE NORTHERN PORTION OF THE LAKE MIDDAY...THEN
CONTINUE TO SLIDE EAST AND WEAKEN WEDNESDAY AFTERNOON ACROSS
SOUTHEAST ONTARIO. THE GRADIENT IS EXPECTED TO TIGHTEN SLIGHTLY
FROM THE SOUTH...WITH WINDS INCREASING THIS MORNING TO ARND 15 TO
25KT. THEN AS THE LOW SLIDES EAST WINDS WILL BECOME WEST AND
DIMINISH TO ARND 10 TO 20 KT LATE TONIGHT. WAVES SHUD BE ABLE TO
BRIEFLY BUILD ACROSS THE LAKE TO ARND 2-4FT...THEN WITH A LIGHTER
GRADIENT ARRIVING WED WAVES WILL SUBSIDE TO ARND 2 FT OR LESS. IN
THE DEPARTING SFC LOW WILL BE A MUCH WEAKER GRADIENT...WITH WINDS
GENERALLY LIGHT FROM THE NORTH ARND 5 TO 10 KT ACROSS THE NORTHERN
HALF OF THE LAKE AND AROUND 10 KT FROM THE SOUTH FOR THE SOUTHERN
HALF OF THE LAKE. A WARM FRONTAL BOUNDARY WILL LIFT NORTH ACROSS
THE SOUTHERN PORTION OF THE LAKE EARLY THUR...WITH MUCH WARMER AIR
LIFTING OVER THE LAKE. AT THIS TIME FEEL THAT FOG MAY NOT
DEVELOP...BUT COULD SEE SOME HAZY CONDITIONS DEVELOP LATE IN THE
WEEK. SOUTH/SOUTHEAST WINDS FOR THE WEEKEND. THE UPPER FLOW
PATTERN DOES LOOK TO SHIFT SUNDAY OR MONDAY BRINGING A COLD FRONT
ACROSS THE LAKE WITH A SHIFT TO NORTHERLY WINDS WHICH MAY BE
RATHER BREEZY EARLY NEXT WEEK.
BEACHLER
&&
.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:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
923 AM CDT Tue Aug 19 2014
.UPDATE...
ISSUED AT 923 CDT TUE AUG 19 2014
Area of showers and thunderstorms associated with an upper-level
wave is currently crossing the Mississippi River into west-central
Illinois. 1417z radar imagery shows leading edge of precip extending
from Galesburg...to Rushville...to Bowling Green Missouri. Based
on timing tools, showers/thunder will arrive along the I-55
corridor by midday. HRRR and other high-res models generally show
the precip area weakening as it pushes eastward through the
morning, then potentially re-developing across east-central
Illinois later this afternoon. Made some adjustments to hourly
PoPs today, mainly to increase to categorical along/west of I-55
during the morning. Once the wave passes, rain chances will come
to an end across the Illinois River Valley by mid to late
afternoon, followed by a return to partly to mostly sunny skies.
Further east, rain chances will linger throughout the day before
coming to an end by evening.
&&
.SHORT TERM...(This afternoon through Wednesday)
ISSUED AT 336 AM CDT TUE AUG 19 2014
Short term models have trended slower with the front and precip that
is currently supposed to be moving into the area. But will still
have chance of precip starting in the northwest parts of the cwa
this morning. Then will progress the pcpn chances southeastward
across the cwa during the day. By this evening, most of the pcpn
will be in the eastern two thirds of the area with the highest pops
in the southeast. By overnight, the pcpn should have moved southeast
of the area so most of the area should be dry overnight, though will
keep a slight chance of pops in the southeast after midnight. Could
be some additional pcpn in the southwest late tonight, but models
keep most of pcpn west of the area through 12z.
Temps will begin the slow warming tomorrow, and am expecting mid to
upper 80s throughout the area today.
&&
.LONG TERM...(Wednesday night through Monday)
ISSUED AT 347 AM CDT TUE AUG 19 2014
Models still pretty consistent with the development and lift of a
boundary through the Midwest on Wednesday. Boundary will have little
reflection at the sfc with very weak flow/weak wind shift, and
thermal gradient is better represented in the mid levels. Boundary
will provide a weak focus for waves moving through the region as the
boundary lifts to the NE through the area for Wed/Wed night. Though
Wed is lacking signif pop for now, the timing of the progression is
better for early evening and into the overnight on Wednesday
night/shifting to the northeast for Thurs. Position of the boundary
or the remnants thereof will be where the majority of the precip
chances will be...increasing to the north, particularly north of
Interstate 74 from Thursday to Saturday. Ample sfc based instability
in the form of hot and humid conditions as the ridge over the
southwest opens and spreads signif heat into the Midwest. Models
have also shown consistency with 850 mb temps in the 19-25C range
from Wednesday through Sunday. This will drive the temps into the
upper 80s/lower 90s with heat indices in the upper 90s/approaching
100F. A far more summer-like pattern than much of the season so far,
and well above normal for this time of year...with breaks from the
heat provided by any thunderstorms that may have the chance to form
from more diurnal instability with any frontal forcing further to
the north. Into the extended, day 7/just into day 8, models diverge
in solutions with major difference in breaking down the upper ridge
for the Midwest.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 609 AM CDT TUE AUG 19 2014
Cold front is still back northwest of the area, but still
forecasted to move through the area, affecting all TAF sites this
through afternoon. However, radar loops show a complex of
thunderstorms in northern MO that could move into central IL this
morning and effect some of the TAF sites, possibly SPI and DEC.
Short term models do show some pcpn moving through the area this
morning, but appears it will diminish as it moves into the area.
Then the front drops into the area a few hours later and this will
bring a chance of thunderstorms to the TAF sites for the afternoon
and early evening. The early stuff could be just showers, but
since the front will be right on the heels of the current complex
coming out of MO, will opt to just have VCTS for all TAFs to cover
both events. Believe t-storms will be more scattered as well. Also
VCTS will be in the TAFs longer than necessary, but only because
of two events. Not expecting cigs to go down today, but having
some light fog issues at mainly CMI, with some very light fog at
PIA and BMI. This fog will burn off quickly, like yesterday
morning. Winds will be south to southwest through the morning and
then become southwest just ahead of the front, and then westerly
or light and variable after FROPA.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...AUTEN
LONG TERM...HJS
AVIATION...AUTEN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
106 AM CDT TUE AUG 19 2014
.DISCUSSION...
650 PM...EARLY EVENING UPDATE...CONVECTION FIRING ACROSS CENTRAL
WI WILL CONTINUE THIS EVENING WITH ADDITIONAL THUNDERSTORMS
RAPIDLY DEVELOPING OVER FAR NORTHERN IA AND SOUTHERN MN. THIS
ACTIVITY WILL SLOWLY SAG SOUTH BUT PROBABLY NOT REACH NORTHERN IL
UNTIL AFTER 04Z-05Z. ACTIVITY WILL THEN SPREAD SOUTHEAST ACROSS
MAINLY THE NORTHERN TWO THIRDS OF THE CWA OVERNIGHT. SHORT TERM/
HI RES GUIDANCE IS IN FAIR AGREEMENT WITH MUCH OF THE AREA NOW
STAYING DRY THROUGH MIDNIGHT. HAVE UPDATED GRIDS/ZFP FOR THESE
TRENDS ALONG WITH MOSTLY CLEAR SKIES OVER MUCH OF THE AREA AS CU
FIELD DISSIPATES...THOUGH HIGH CLOUDS WILL LIKELY QUICKLY SPREAD
ACROSS THE AREA LATER THIS EVENING AS STORMS APPROACH. NO CHANGES
TO LIKELY POPS OVERNIGHT THOUGH POPS MAY NEED TO BE LOWERED ACROSS
THE FAR SOUTH AS TRENDS EMERGE. CMS
//PREV DISCUSSION...
239 PM CDT
SYNOPSIS...A WARMER AND NOTICEABLY MORE HUMID PATTERN WILL BE
DEVELOPING THROUGH MID WEEK. IN ADDITION TO THE WARMTH AN EVOLVING
UPPER AIR PATTERN WILL BRING PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS THROUGH THE WEEKEND. HIGH TEMPERATURES LATER IN THE
WEEK MAY BE DICTATED BY THE CONVECTION.
TONIGHT...
A LOW PRESSURE TROUGH IS OVER MINNESOTA AND IT WILL BECOME A CLOSED
LOW OVER WISCONSIN AND LAKE SUPERIOR TUESDAY EVENING. AT THE
SURFACE THERE IS A LOW PRESSURE TROUGH OVER MINNESOTA THAT WILL
BECOME A CLOSED LOW OVER WISCONSIN TOMORROW MORNING. THE LOW WILL
PUSH EAST OF THE LAKE WEDNESDAY.
EXPECTING THE FIRST ROUND OF STORMS TO MOVE INTO THE RFD AREA THIS
EVENING WITH THE MAJORITY OF CONVECTIVE ACTIVITY REMAINING OVER
WISCONSIN CLOSER TO THE LOW. THE FIRST WAVE WILL WEAKEN AS IT
PUSHES EAST. A SECOND WAVE FORMS AHEAD OF A VORT STREAMER OVERNIGHT
AND THINKING THIS WILL BE THE MAIN SHOW TONIGHT. EXPECTING ACTIVITY
TO REMAIN NORTH OF I-80 MOST OF THE NIGHT. ACTIVITY WILL THEN SPREAD
SOUTH AND EAST COVERING AREAS EAST OF I-39 EARLY TUESDAY MORNING.
THIS ACTIVITY WILL WEAKEN THROUGH THE MORNING AND CONTINUE SOUTHEAST
OUT OF THE WARNING AREA.
THE FIRST CONCERN OVERNIGHT IS HEAVY RAIN AS PWAT VALUES WILL BE
BETWEEN 1.5 AND 1.75 INCHES. CAPE VALUES WILL BE AROUND 1000 J/KG
THIS EVENING AND THEN DIMINISH OVERNIGHT. SHEAR VALUES ARE 20-30 KT
SO SEVERE WEATHER IS NOT EXPECTED...BUT SMALL HAIL MAY OCCUR WITH
THE STRONGEST STORMS. STEERING LEVEL FLOW IS ALSO WEAK SO STORMS
WILL BE SLOW MOVING WHICH COULD ENHANCE RAINFALL TOTALS.
THE OTHER CONCERN IS FOG TONIGHT. IF WE CLEAR OUT AT ALL EXPECTING
AREAS OF DENSE FOG TO DEVELOP. HAVE MEDIUM CONFIDENCE IN SKY COVER
SO ONLY HAVE PATCHY FOG IN THE FORECAST TONIGHT AFTER MIDNIGHT.
TUESDAY AND TUESDAY NIGHT...
MORE STORMS ARE EXPECTED AS THE LOW SHIFTS EAST OVER WISCONSIN.
EXPECTING FOG/LOW STRATUS/GENERAL CLOUD COVER TO THIN TUESDAY
MORNING. HEATING WILL RESULT IN DECENT CAPE VALUES. THE MOISTURE
RICH NAM FEATURES THE HIGHEST CAPE VALUES AROUND 3000 J/KG BUT THE
MORE CONSERVATIVE GFS ONLY SHOWS LESS THAN 1000 J/KG. SHEAR VALUES
STILL LOOK MARGINAL AROUND 35 KT. BUT PWAT VALUES WILL BE A BIT
LOWER AT 1.3 TO 1.5 INCHES. HEAVY RAIN IS STILL POSSIBLE BUT STORMS
SHOULD BE MOVING AT A BETTER PACE WITH STRONGER STEERING LEVEL
FLOW. THE FORCING WILL BE A COMBO OF THE LOWS FRONT THAT MOVES
THROUGH IN THE LATE AFTN/EVENING AND VORTICITY STREAMERS THAT ROTATE
AROUND THE LOW. HAVE MEDIUM CONFIDENCE IN WIDESPREAD TS
COVERAGE...BUT KEPT POPS IN THE CHANCE RANGE DUE TO LOW CONFIDENCE
IN WHEN AND WHERE STORMS WILL DEVELOP. HAIL AND STRONG WINDS ARE
POSSIBLE IN ADDITION TO THE HEAVY DOWNPOURS.
TEMPS REMAIN A CHALLENGE AS WE COULD BE WARMER IF SKY COVER IS ON
THE WEAKER SIDE. HOWEVER...HAVE MEDIUM CONFIDENCE IN WIDESPREAD TS
COVERAGE SO KEPT HIGH TEMPS IN THE LOW TO MID 80S.
JEE
WEDNESDAY THROUGH SUNDAY...
THE UPPER LOW OVER THE UPPER GREAT LAKES WILL START TO MOVE MORE
QUICKLY TO THE NORTHEAST WEDNESDAY MORNING AS NORTHERN PACIFIC
TROUGHING PUSHES INLAND OVER WESTERN CANADA. THIS HELPS TO PUSH
CUTOFF LOW PRESSURE ONTO THE CALIFORNIA COAST WITH BOTH OF THESE
FEATURES HELPING TO DRIVE UPPER RIDGE DEVELOPMENT OVER THE HIGH
PLAINS. THE LOCAL AREA WILL BE BETWEEN THE DEPARTING UPPER LOW AND
THE APPROACHING RIDGE WEDNESDAY MORNING WITH WEAK LOW LEVEL FLOW
IN PLACE AS WELL. THIS SHOULD RESULT IN DRY WEATHER FOR MUCH OF
WEDNESDAY BEFORE MID LEVEL BAROCLINICITY INCREASES LATE IN THE DAY
AND MORE SO IN THE EVENING AS THE RIDGE APPROACHES. PRECIPITABLE
WATER VALUES WILL INCREASE MARKEDLY WITH THE ARRIVAL OF THE MID
LEVEL WARM ADVECTION LEADING TO MOIST ASCENT WEDNESDAY EVENING AND
WEDNESDAY NIGHT. THIS LIFT ALONE MAY BE ENOUGH TO PRODUCE SHOWERS
AND THUNDERSTORMS AND MAY BE AIDED BY THE PASSAGE OF AN UPPER WAVE
WHICH GUIDANCE HAS BEEN HINTING AT. THIS IS CERTAINLY PLAUSIBLE
GIVEN THE PRESENCE OF THE DEEP TROUGH TO THE WEST AND THE TENDENCY
FOR WAVES TO EMANATE FROM IT. WILL CARRY HIGHEST POPS LATE
WEDNESDAY EVENING THROUGH THURSDAY MORNING. THE RIDGE AXIS WILL
SHIFT EASTWARD ACROSS THE AREA THROUGH FRIDAY. THE AMPLITUDE OF
THE RIDGE AND THEREFORE THE POSITIONING OF THE TRACK OF
SHORTWAVES/THUNDERSTORMS ALONG ITS NORTHERN PERIPHERY WILL BE
DRIVEN BY THE SPEED WITH WHICH THE LARGE WESTERN UPPER TROUGH
EVOLVES EASTWARD. THE GFS CONTINUES TO BE MORE PROGRESSIVE WITH
THE TROUGH AND THEREFORE SHARPER WITH THE RIDGE SUGGESTING THAT
THE MAIN STORM TRACK WILL BE NORTH OF THE LOCAL AREA FRIDAY
WHEREAS THE SLOWER AND LOWER AMPLITUDE ECMWF KEEPS THE FAVORED
TRACK ACROSS THE AREA INTO THE WEEKEND. THE UPPER TROUGH WILL
EVOLVE EASTWARD PUSHING THE RIDGE TO THE EAST AND BRINGING A COOL
FRONT INTO THE REGION LATE IN THE WEEKEND. THE BIGGEST UNCERTAINTY
IS THE TIMING. WITH PRECIPITABLE WATER VALUES OVER 2 INCHES FROM
THURSDAY ONWARD HEAVY RAINFALL WILL BE A CONCERN WITH ANY
STORMS...ESPECIALLY IF MULTIPLE ROUNDS ARE ABLE TO AFFECT THE AREA
THROUGH THE WEEKEND. HOWEVER A SHARPER RIDGE WOULD RESULT IN A
SHIFT IN THE TRACK TO THE NORTH AND STRONGER CAPPING LOCALLY.
TEMPERATURES WILL BE WARMING INTO THE MID 80S WEDNESDAY AND MOSTLY
MID AND UPPER 80S FROM THURSDAY INTO THE WEEKEND. LAKESHORE AREAS
WILL LIKELY BE COOLER MOST DAYS WITH LAKE INFLUENCES EXPECTED DUE TO
A RATHER LIGHT LOW LEVEL FLOW. THUNDERSTORMS AND ANY REMNANT
INFLUENCES MAY NEGATIVELY AFFECT HIGHS DEPENDING ON THEIR TIMING.
CANNOT RULE OUT SOME 90 DEGREE READINGS IN THE WEST AND SOUTH LATE
IN THE WEEK...ESPECIALLY IF THUNDERSTORM ACTIVITY KEEPS AT A
MINIMUM.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* A PERIOD OF SHRA/TSRA POSSIBLE SOMETIME BETWEEN 08Z-11Z.
* POTENTIAL FOR LOWER CIGS LATE TONIGHT INTO TUE MORNING.
* CHANCE FOR SCATTERED SHRA/TSRA MUCH OF TUE WITH A SLIGHTLY MORE
FAVORED TIME DURING THE AFTERNOON.
KREIN
//DISCUSSION...UPDATED 06Z...
A QUIET EVENING IS EXPECTED OVER LOCAL AIRPORTS BEFORE TSRA
CHANCES INCREASE OVERNIGHT.
AN UPPER LEVEL DISTURBANCE MOVING EAST THROUGH WISCONSIN CONTINUES
TO GENERATE A LINE OF THUNDERSTORMS EXTENDING FROM NEAR OSHKOSH
SOUTHWEST TO NEAR DES MOINES ALONG A WEAK COLD FRONT...WITH AN
ADDITIONAL CLUSTER OF SHOWERS AND EMBEDDED THUNDERSTORMS RIGHT
UNDER THE MAIN UPPER CIRCULATION CENTER. LATEST TRENDS INDICATE
THAT THE UPPER LEVEL SYSTEM IS TRACKING ALMOST DUE EAST WHILE THE
MAIN CONVECTIVE LINE SLOWLY SAGS SLIGHTLY SOUTH OF EAST. HAVE
DECREASING CONFIDENCE IN THE POTENTIAL FOR ANY OF THE TS TO REACH
ANY OF TERMINALS EXCEPT FOR ROCKFORD. ALSO...THE LATEST MODEL
GUIDANCE IS SHOWING THAT STEERING FLOW IS TURNING MORE DUE
WESTERLY AS THE UPPER SYSTEM MOVES EWD...WHICH WOULD THEN CAUSE
THE SOUTHERN END OF THE CONVECTIVE LINE TO STRETCH OUT IN A MORE
EAST-WEST ORIENTATION NEAR THE IL/WI BORDER. HOWEVER...THERE IS
STILL SOME DEVELOPMENT ALONG THE SRN END OF THE LINE OVER NERN IA
INTO CNTRL IA...SO CONFIDENCE IS NOT HIGH ENOUGH TO PULL THE TS
FROM THE TAFS FOR THE LATE NIGHT HOURS AS THERE IS STILL SOME
MOISTURE TRANSPORT AND BROAD SCALE LIFT OVER NRN IL WHERE 850MB
WINDS ARE STILL WSWLY. ANOTHER FACTOR POINTING TO A LOWER TS
POTENTIAL IS THE LACK OF STRONG SFC FORCING AND THAT THE SYSTEM IS
ALMOST ENTIRELY RELYING ON UPPER LEVEL FORCING. SO...TO MAKE A
SHORT STORY LONG...WILL MAINTAIN THE TS IN THE TAFS BTWN
08-11Z...AND REFINE THE FORECAST WHEN CONFIDENCE IS A LITTLE
HIGHER.
WHAT THUNDER THAT DOES MANAGE TO MOVE SOUTH OF THE WISCONSIN
BORDER SHOULD DISSIPATE BEFORE DAYBREAK...BUT WITH A MOIST AIRMASS
IN PLACE AND THE MAIN SYNOPTIC SCALE UPPER LOW MOVING OVER NRN
WISCONSIN BY MID DAY TUESDAY...THERE WILL STILL BE ADEQUATE
CYCLONIC FLOW ALOFT THAT SCT SHRA AND ISOLD TSRA COULD STILL
DEVELOP DURG THE DAYTIME HOURS. CHANCES FOR MORE ORGANIZED TS WILL
INCREASE THROUGH THE AFTERNOON AS ANOTHER MID LEVEL IMPULSE TRACKS
AROUND THE SRN PERIPHERY OF THE MAIN UPPER LOW.
AS FOR WINDS...LIGHT SWLY WINDS WILL CONTINUE IN ADVANCE OF THE
WEAK COLD FRONT...AND INCREASE THROUGH THE MORNING AS THE SFC
PRESSURE GRADIENT STRENGTHENS. BY LATE MORNING...SWLY WINDS SHOULD
INCREASE TO 10-15KT WITH OCNL GUSTS OF 15-20KT PERSISTING THROUGH
EARLY EVENING WHILE GRADUALLY VEERING TO WESTERLY BY LATE
AFTERNOON.
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* LOW CONFIDENCE IN TIMING AND COVERAGE OF TS ASSOCIATED WITH THE
COLD FRONT AND THE DIRECT IMPACT ON THE TERMINALS.
* MEDIUM TO HIGH CONFIDENCE IN WIND SPEED AND DIRECTION...THOUGH
THE WIND FIELD COULD BE LOCALLY DISRUPTED BY ANY TS THAT DO
DEVELOP.
* LOW IN MVFR CIGS OCCURRING LATE TONIGHT INTO TUE MORNING.
* LOW IN WHETHER TSRA OCCURS TUESDAY AND IN SPECIFIC TIMING.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...CHANCE OF TSRA AND LOWER CIGS DURING THE NIGHT.
THURSDAY-SATURDAY...PERIODS OF TSRA POSSIBLE.
SUNDAY...SLIGHT CHANCE OF TSRA.
MTF
&&
.MARINE...
239 PM CDT
LOW PRESSURE OVER MINNESOTA WILL MOVE OVER WISCONSIN TOMORROW AND
THEN OVER THE LAKE TOMORROW EVENING AND NIGHT. WINDS WILL BECOME
SOUTH ACROSS THE LAKE AND INCREASE TO 15 TO 25 KT OVERNIGHT. AS THE
LOW MOVES OVER THE LAKE TOMORROW...WINDS WILL DIMINISH SLOWLY OVER
THE SOUTH HALF AND BECOME SW. ON THE NORTH HALF...WINDS WILL ALSO
DIMINISH AND BECOME SE TO E AHEAD OF THE LOW. THE LOW SHIFTS EAST
OF THE LAKE TUESDAY NIGHT AND WINDS BECOME NW 10-15 KT.
THE LOW SHIFTING TO THE EAST WILL LEAVE A WEAK PRESSURE GRADIENT
IN ITS WAKE. THIS WILL RESULT IN LIGHT ONSHORE OR VARIABLE WINDS
WEDNESDAY WITH BEFORE A SOMEWHAT BETTER ORGANIZED PRESSURE
GRADIENT SPREADS IN WITH LOW PRESSURE FROM THE CENTRAL HIGH PLAINS
TO NORTHERN MANITOBA. THIS WILL BRING MAINLY SOUTH TO SOUTHEAST
WINDS ACROSS THE LAKE THURSDAY...WITH OCCASIONAL EAST WINDS OVER
THE FAR NORTH...BUT EVEN THEN THE FLOW MAY BE WEAK ENOUGH TO
SUPPORT A SHIFT TO ONSHORE WINDS THURSDAY AFTERNOON. SOUTH TO
SOUTHEAST WINDS ARE FAVORED THROUGH THE WEEKEND BUT THERE MAY BE
QUITE A BIT OF VARIABILITY IF THE LOW PRESSURE TO THE WEST EVOLVES
MORE SLOWLY AS SOME FORECAST GUIDANCE INDICATES. THE UPPER FLOW
PATTERN DOES LOOK TO SHIFT SUNDAY OR MONDAY BRINGING A COOL FRONT
ACROSS THE LAKE WITH A SHIFT TO NORTHERLY WINDS WHICH MAY BE
RATHER BREEZY.
JEE/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:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1152 PM CDT Mon Aug 18 2014
.UPDATE...
ISSUED AT 900 PM CDT MON AUG 18 2014
Skies have become mostly clear across central and SE Illinois this
evening as diurnal heating ends. Although a few pockets of light
fog are possible early tonight, the next main forecast feature
will be the chance for thunderstorms overnight as an upper level
shortwave and cold front move into central IL. Have trimmed back
POPs before midnight as current radar and satellite indicate
storms are still several hours away. HRRR model simulated
reflectivity has been depicting movement of the system well in
northern IA, southern MN, southwest WI this evening and has been
used as a guide for timing through the first few hours of Tuesday.
Currently the system is associated with a slight risk (15% +) of
severe winds and hail to our northwest, but as it approaches
central IL, CAPE of 3000 J/kg should be diminishing to around 1500
or less with marginal 0-6 km bulk shear around 25-30 kts. This is
enough for only a 5% severe risk from the Illinois River
northwest. To the south, risk of severe storms is negligible, but
at least a slight chance for storms will reach as far as SE
Illinois by early morning. Have sent updates for
POP/Temp/Humidity/Wind trends this evening/early tonight.
&&
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 311 PM CDT MON AUG 18 2014
Earlier stratus has given way to diurnal type clouds over central
and southeast Illinois early this afternoon, underneath a weak high
pressure axis. Leading edge of shortwave currently seen on water
vapor imagery pushing through Minnesota and northern Iowa, with a
more potent vorticity maximum moving out of North Dakota.
Convection ahead of the shortwave expected to begin over the next
couple hours over northern Iowa, where skies have been sunny and
CAPE`s are over 3000 J/kg per SPC mesoanalysis. High-resolution
models pushing the first wave of storms into Wisconsin with another
line forming in southern Minnesota/northern Iowa later this evening.
The second line is more of a concern for us as it will have a
southeast trajectory. However, most of the models show some fading
of the line with more of the energy staying to our north, and a
separate convective cluster developing over northwest Missouri
overnight. Have adjusted the PoP`s in our area to be primarily after
midnight, and largely eliminated them south of I-70.
Associated surface boundary expected to push into central Illinois
Tuesday afternoon as the upper wave arrives. Some concerns with
severe weather potential across east central and southeast Illinois,
as development takes place early afternoon and bulk shear increases
during the peak heating time. Latest Day2 SPC convective outlook
indicates a severe threat southeast of a Danville to Effingham line,
with NAM indicating a 2 pm to 7 pm time frame being the most
concern.
&&
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 311 PM CDT MON AUG 18 2014
Tuesday evening will see decreasing storm chances from north to
south as a shortwave in the upper level trough over the Great Lakes
advances east of IL. We are in the day 2 slight risk in our
southeast counties, so we can`t rule out some lingering strong
storms into early evening, but the main threat should advance
southeast of IL by mid evening.
Additional storm chances re-develop across our far S-SW counties late
Tue night as a 300mb 75kt jet max in the back side of the trough
generates some lift in the left exit region. Minor rain/storm
chances will continue on Wednesday as the jet max progresses
eastward over Illinois, but only slight chances are expected.
Wednesday night, a warm front developing across our northern
counties oriented from NW to SE will become a focus for a round of
storms, with chances increasing to likely after midnight along and
north of I-74. Storms should progress northward with the warm front
on Thursday. However, storms chances are expected to linger north of
a line from Peoria to Paris Thursday and Thursday night.
Height rises and mid-level warming on Friday and Saturday should
help to keep provide a capping layer, and reduce storm chances
across central IL. The may be an isolated late afternoon or early
evening flare-up of a storm, but most areas should stay dry.
Rain-free conditions are forecast to continue into Sunday by the
ECMWF and GFS. They both show a cold front arriving later Sunday
night and wash-out as it passes across IL on Monday. The weakening
front is not expected to trigger much in the way of storms at this
point, but confidence is low on that scenario staying dry.
Heat and humidity will definitely dominate the last half of this
week, as highs climb into the upper 80s and lower 90s, with heat
index readings in the mid to upper 90s. Some relief will come on
Monday behind the cold front, with low to mid 80s for highs and
lowering dewpoints into the 60s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1152 PM CDT MON AUG 18 2014
Patchy fog resulting in VLIFR to MVFR conditions in place from
around K1H2-KAAA-KCMI eastward, with a line of thunderstorms
approaching northern IL from the northwest. Fog expected to
dissipate as light SSW winds ahead of the line of thunderstorms
promotes mixing. This line expected to weaken as it approaches and
mainly affect TAF sites from KPIA and KBMI northward. Have
included VCTS in central IL TAFs to address potential for
thunderstorms, but likelihood of MVFR conditions looks too low for
explicit mention at this time. A break in shower/thunderstorm
activity likely in the morning, then an upper level shortwave and
daytime heating should produce a re- intensification of storms
along the cold frontal boundary lingering over central Illinois.
Have brought VCTS and ceilings near MVFR thresholds for the
remainder of the afternoon to account for this. Starting around
00Z, conditions expected to improve as frontal boundary and upper
level shortwave moves east of the area.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ONTON
SHORT TERM...GEELHART
LONG TERM...SHIMON
AVIATION...ONTON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
620 PM CDT WED AUG 20 2014
.SHORT TERM /TONIGHT/...
ISSUED AT 340 PM CDT WED AUG 20 2014
TONIGHTS FORECAST IS QUITE DIFFICULT AND THE MODELS ARE NOT MUCH
HELP. A WARM FRONT ACROSS IOWA STRETCHES FROM A LOW OVER WEST
CENTRAL SOUTH DAKOTA. THETA-E ADVECTION AND SOME MODEST INSTABILITY
KEPT THUNDERSTORMS FESTERING AHEAD OF THE FRONTAL BOUNDARY ALL DAY
LONG AND SHEAR ACTUALLY INCREASED THROUGH THE AFTERNOON HOURS. THE
MODELS CONTINUE THE SHOWERS/STORMS ALONG AND AHEAD OF THE FRONTAL
BOUNDARY IN A ZONE OF WARM ADVECTION THROUGH THE AFTERNOON HOURS
INTO EARLY EVENING. THE HRRR AND HOPWRF THEN SQUELCH THE PRECIP IN
IOWA OVERNIGHT WHILE THE NAM CONTINUES TO DEVELOP STORMS ACROSS
NORTH CENTRAL/NORTHEAST IOWA...ESPECIALLY WITH A LOW LEVEL JET THAT
INTENSIFIES LATER THIS EVENING. IT IS VERY HARD TO SAY WHERE THAT
BOUNDARY WILL LIFT TO THIS EVENING...OR WILL IT REMAIN FAIRLY
STATIONARY. I AM REASONABLY CERTAIN THAT WE WILL NOT BE DRY ACROSS
THE NORTH BUT I AM SKEPTICAL ABOUT KEEPING 60-70 POPS IN THAT AREA
GIVEN THE TRENDS FOR THE PRECIP TO SLOWLY LIFT NORTH.
THE MAIN ADJUSTMENTS TO THE GOING FORECAST WERE TO LOWER POPS SOME
ACROSS THE NORTH AND MENTION HEAVY RAIN ACROSS A PART OF THE NORTH
CENTRAL AND NORTHEAST. HOWEVER...IF THE NAM12 IS CORRECT MY
FORECAST WILL NEED TO BE ADJUSTED ONCE THE LLJ COMES INTO PLAY AFTER
03Z OR SO AS HIGHER POPS WILL BE NEEDED FURTHER SOUTH. HEAVY
RAINFALL WILL ALSO BE MORE OF A CONCERN ACROSS AREAS NORTH OF
HIGHWAY 20.
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 340 PM CDT WED AUG 20 2014
RELATIVELY ACTIVE CONDITIONS TO PERSIST FOR MUCH OF THE LONG TERM
WITH BROAD WSW FLOW ALOFT AND SURFACE BOUNDARY NEARBY. ANY ONGOING
CONVECTION ON THURSDAY MORNING SHOULD DISSIPATE WITH FORCING
WEAKENING. WARM SECTOR WILL BE IN PLACE WITH TEMPERATURES CLIMBING
NICELY THROUGH THE DAY. STILL MAY SEE SOME MID TO HIGH CLOUDS
OVERHEAD AND THIS MAY LIMIT DAYTIME HIGHS...HOWEVER STILL A VERY
WARM AND HUMID DAY EXPECTED FOR MOST LOCATIONS. SURFACE BOUNDARY
WILL EASE INTO NORTHERN IOWA ON THURSDAY NIGHT WITH SOME SCATTERED
CONVECTION EXPECTED ALONG THE FRONT OVERNIGHT. THESE STORMS ARE
EXPECTED TO WEAKEN OVERNIGHT TOWARD DAYBREAK AS INFLOW WEAKENS AND
COL REGION PUSHES INTO THE STATE. FRIDAY WILL SEE THE COL PASS
THROUGH IOWA WITH LIMITED CONVECTION CHANCES FOR MUCH OF THE DAY.
HOWEVER...A MORE VIGOROUS SHORTWAVE WILL EJECT INTO THE PLAINS
LATER FRIDAY WITH INCREASING FLOW INTO THE FRONT LATE FRIDAY INTO
FRIDAY NIGHT. MODELS HAVE ALL BEEN INDICATING RATHER ROBUST
CONVECTION BY LATE FRIDAY ACROSS THE PLAINS PUSHING INTO IOWA
OVERNIGHT. HAVE CONTINUED THE HIGHER POPS ON FRIDAY
NIGHT...ESPECIALLY ACROSS THE NORTHWEST WHERE THE BEST FORCING AND
INFLOW INTO SYSTEM IS ANTICIPATED. THE THREAT FOR CONVECTION WILL
PERSIST INTO THE WEEKEND AND EARLY NEXT WEEK AS THE FRONTAL
BOUNDARY REMAINS NEAR THE STATE. AT THIS POINT...IT APPEARS MUCH
OF THE CONVECTION THIS WEEKEND WILL BE NEAR NORTHERN IOWA WITH HOT
AND HUMID CONDITIONS IN THE SOUTH. THE BULK OF THE SYSTEM IS NOT
EXPECTED TO PASS THROUGH THE REGION UNTIL THE MIDDLE OF NEXT WEEK
WHEN GOOD COVERAGE OF STORMS IS ANTICIPATED TUESDAY NIGHT INTO
WEDNESDAY. TEMPERATURES WILL REMAIN VERY WARM TO HOT SOUTH OF THE
BOUNDARY DURING THIS TIME.
THE THREAT FOR HEAVY RAINFALL WILL BE EVER PRESENT WITH THIS
CONVECTION FOR MUCH OF THE FORECAST. PWAT VALUES WILL IN GENERAL
BE AT OR ABOVE 1.50" WITH CONVECTION EAST OR SOUTHEAST AND
TRAINING A POSSIBILITY FROM TIME TO TIME. WHILE WIDESPREAD
FLOODING IS NOT EXPECTED GIVEN MATURE VEGETATIVE
GROWTH...LOCALIZED FLOODING MAY OCCUR. THE PRIMARY FLASH FLOOD
THREAT WILL REMAIN IN URBAN AREAS. HOWEVER...IF SEVERAL NIGHTS OF
RAIN DO OCCUR IN THE SAME AREA...A MORE GENERALIZED FLASH FLOOD
THREAT MAY MATERIALIZE.
THE OTHER CONCERN WILL BE WITH HOT AND HUMID CONDITIONS SOUTH OF
THE BOUNDARY. HEAT INDEX VALUES ARE EXPECTED TO CLIMB ABOVE 100
DEGREES FROM TIME TO TIME AND MAY BECOME PROBLEMATIC...ESPECIALLY
IN SOUTHERN IOWA SHOULD SEVERAL DAY STRING TOGETHER OF HOT AND
STICKY CONDITIONS. MUCH WILL DEPEND ON THE EXTEND OF CONVECTION
AND WHERE OUTFLOW BOUNDARYS AND SUBSEQUENT CONVECTION END UP. AT
THIS POINT...GIVEN THE UNCERTAINTY...NO HEADLINES FOR HEAT WILL BE
ISSUED.
&&
.AVIATION...21/00Z
ISSUED AT 614 PM CDT WED AUG 20 2014
DISTURBANCE PUSHING EASTWARD WILL BRING CHANCES FOR SHRA/TSRA TO
NORTHERN SITES THROUGH 12Z. HAVE INCLUDED MENTION AT
KDSM/KFOD/KMCW/KALO. CONDITIONS WILL DROP TO MVFR OR IFR AT TIMES
WITH TSRA. IN ADDITION...BR/FG MAY REDUCE VISIBILITIES FURTHER
NEAR 12Z. WINDS WILL REMAIN STRONGER...AND HAVE ONLY BROUGHT
VISIBILITIES DOWN TO IFR ATTM. HAVE LEFT KOTM OUT WITH
PRECIPITATION FURTHER NORTH. WINDS WILL REMAIN SOUTHERLY THROUGH
THURSDAY AND MAY BE GUSTY AFTER 18Z.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...COGIL
AVIATION...AWB
AREA FORECAST DISCUSSION
NWS DES MOINES IA
604 PM CDT TUE AUG 19 2014
.SYNOPSIS...
ISSUED AT 305 PM CDT TUE AUG 19 2014
WEAK HIGH PRESSURE OVER IOWA WILL MOVE EAST AS A WARM FRONT
DEVELOPS TO THE SOUTH AND BEGINS TO LIFT NORTH TONIGHT. THE FRONT
WILL LIFT NORTH OF THE STATE ON WEDNESDAY NIGHT. STRONG S/WV WILL
MOVE UP THE BACK SIDE OF THE UPPER LEVEL RIDGE AND PUSH A COLD
FRONT ACROSS THE STATE THIS WEEKEND.
&&
.SHORT TERM /TONIGHT/...
ISSUED AT 305 PM CDT TUE AUG 19 2014
A SURFACE LOW DEVELOPING OVER NORTHEAST COLORADO WILL SHIFT INTO
NORTHWEST NEBRASKA OVERNIGHT. AN ASSOCIATED WARM FRONT WILL EXTEND
FROM THE LOW THROUGH EASTERN NEBRASKA AND INTO SOUTHWEST IOWA AND
NORTHERN MISSOURI BY 12Z WEDNESDAY BEFORE SURGING NORTH THROUGH THE
DAY WEDNESDAY. STRONG THETA-E ADVECTION IS FORECAST TO LIFT ACROSS
CENTRAL IOWA DURING THE OVERNIGHT HOURS...ESPECIALLY AFTER 06Z.
FORCING IS WEAK BUT DOES IMPROVE OVERNIGHT AS A LOW LEVEL JET
FOCUSES INTO SOUTHWEST IOWA. ALOFT A WEAK SHORTWAVE IS PROGGED TO
MOVE ACROSS EASTERN NEBRASKA/SOUTHWEST IOWA. THIS SHOULD BE ENOUGH
TO PRODUCE SHOWERS AND THUNDERSTORMS ACROSS SOUTHWEST INTO CENTRAL
IOWA. STORMS SHOULD MAINLY BE ELEVATED AS LOW LEVEL CONVERGENCE IS
WEAK TO NON EXISTENT. THERE IS ALSO SOME WEAK SHEAR...PERHAPS
ENOUGH FOR AN ISOLATED STORM TO BRIEFLY PRODUCE SOME MARGINALLY
SEVERE TO SEVERE HAIL. THE HIGH RES AND NAM12 MODELS ARE NOT AS
IMPRESSIVE WITH DEVELOPING STORMS ACROSS THE AREA BUT THE SREF DOES
AS DOES PREVIOUS RUN OF THE HI-RES MODELS. THE HRRR IN PARTICULAR
IS FAIRLY BULLISH ON BRINING PRECIP INTO THE SW WHILE THE MEMBERS OF
THE HOPWRF ARE A LITTLE MORE RESERVED...AT LEAST THROUGH 09Z.
SOME POTENTIAL FOR FOG ACROSS THE NORTHEAST OVERNIGHT AS REMAINING
CLOUDS ACROSS THE AREA DISSIPATE WITH SUNSET AND SURFACE RIDGING
MOVES OVERHEAD PRODUCING LIGHT WIND. NOT LOOKING AT DENSE FOG AT
THIS POINT GIVEN THE VERY SHALLOW NATURE OF THE MOISTURE MOVING IN.
GENERALLY WENT WITH PATCHY FOG WORDING HOWEVER ALO/MCW WILL BE EAST
OF THE RIDGE AXIS AND MOISTURE COULD BE ENOUGH FOR A LITTLE MORE
WIDESPREAD FOG SO I MENTION AREAS OF FOG OVER THESE LOCATIONS.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 305 PM CDT TUE AUG 19 2014
A BREAK IN THE CONVECTION IS EXPECTED ON WED AS THE FIRST ROUND OF
THETA-E ADVECTON LIFTS OUT OF THE STATE. A RENEWED THREAT OF
THUNDERSTORMS WILL COME AS THE WARM FRONT LIFTS NORTH AND STRONG
THETA-E ADVECTION TAKES PLACE WED NIGHT. THE H8 SHOWS GOOD SPEED
CONVERGENCE AND THERE IS DIVERGENCE ALOFT...THE FLY IN THE
OINTMENT WILL BE IF THE ATMOSPHERE CAPS OFF OR NOT. AN EML IS IN
PLACE...BUT IT IS NOT ALL THAT STRONG.
WARM AND HUMID WEATHER WILL HOLD INTO THE WEEKEND WITH AFTERNOON
HEAT INDICES IN THE LOW TO MID 90S NORTH...AND 95 TO 105 SOUTH
TUE-THU AFTERNOON. BELOW CRITERIA...BUT WILL MENTION IN THE HWO
WITH ALL THE SCHOOL ACTIVITIES GOING ON.
COOLER WEATHER WILL MOVE IN OVER THE WEEKEND...FIRST DUE TO THE
INCREASED CLOUD COVER...THEN DUE TO THE FRONTAL PASSAGE SAT. COOL
AIR WILL SETTLE IN SLOWLY WITH TEMPS FALLING BELOW NORMAL; FOR MON
AND TUE.
&&
.AVIATION...20/00Z
ISSUED AT 601 PM CDT TUE AUG 19 2014
BOUNDARY LIFTING NORTH ACROSS CENTRAL IOWA MAY AFFECT SITES WITH
SHRA/TSRA AT TIMES NEAR 12Z. CONDITIONS MAY DROP TO MVFR OR IFR AT
TIMES WITH TSRA AT SITES...HAVE ONLY INCLUDED AT SOUTHERN
SITES...KFOD/KDSM/KOTM ATTM. IN ADDITION...BR OR FG MAY DEVELOP
WITH LIGHT WINDS AT NORTHERN SITES NEAR 12Z BRINGING CONDITIONS
DOWN TO MVFR OR IFR. CONDITIONS WILL IMPROVE QUICKLY BEYOND 12Z
WITH WINDS BECOMING SOUTHERLY AND VFR CONDITIONS EXPECTED AGAIN.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MS AUG 14
SHORT TERM...FAB
LONG TERM...MS AUG 14
AVIATION...AWB
AREA FORECAST DISCUSSION
NWS DES MOINES IA
330 PM CDT TUE AUG 19 2014
.SYNOPSIS...
ISSUED AT 305 PM CDT TUE AUG 19 2014
WEAK HIGH PRESSURE OVER IOWA WILL MOVE EAST AS A WARM FRONT
DEVELOPS TO THE SOUTH AND BEGINS TO LIFT NORTH TONIGHT. THE FRONT
WILL LIFT NORTH OF THE STATE ON WEDNESDAY NIGHT. STRONG S/WV WILL
MOVE UP THE BACK SIDE OF THE UPPER LEVEL RIDGE AND PUSH A COLD
FRONT ACROSS THE STATE THIS WEEKEND.
&&
.SHORT TERM /TONIGHT/...
ISSUED AT 305 PM CDT TUE AUG 19 2014
A SURFACE LOW DEVELOPING OVER NORTHEAST COLORADO WILL SHIFT INTO
NORTHWEST NEBRASKA OVERNIGHT. AN ASSOCIATED WARM FRONT WILL EXTEND
FROM THE LOW THROUGH EASTERN NEBRASKA AND INTO SOUTHWEST IOWA AND
NORTHERN MISSOURI BY 12Z WEDNESDAY BEFORE SURGING NORTH THROUGH THE
DAY WEDNESDAY. STRONG THETA-E ADVECTION IS FORECAST TO LIFT ACROSS
CENTRAL IOWA DURING THE OVERNIGHT HOURS...ESPECIALLY AFTER 06Z.
FORCING IS WEAK BUT DOES IMPROVE OVERNIGHT AS A LOW LEVEL JET
FOCUSES INTO SOUTHWEST IOWA. ALOFT A WEAK SHORTWAVE IS PROGGED TO
MOVE ACROSS EASTERN NEBRASKA/SOUTHWEST IOWA. THIS SHOULD BE ENOUGH
TO PRODUCE SHOWERS AND THUNDERSTORMS ACROSS SOUTHWEST INTO CENTRAL
IOWA. STORMS SHOULD MAINLY BE ELEVATED AS LOW LEVEL CONVERGENCE IS
WEAK TO NON EXISTENT. THERE IS ALSO SOME WEAK SHEAR...PERHAPS
ENOUGH FOR AN ISOLATED STORM TO BRIEFLY PRODUCE SOME MARGINALLY
SEVERE TO SEVERE HAIL. THE HIGH RES AND NAM12 MODELS ARE NOT AS
IMPRESSIVE WITH DEVELOPING STORMS ACROSS THE AREA BUT THE SREF DOES
AS DOES PREVIOUS RUN OF THE HI-RES MODELS. THE HRRR IN PARTICULAR
IS FAIRLY BULLISH ON BRINING PRECIP INTO THE SW WHILE THE MEMBERS OF
THE HOPWRF ARE A LITTLE MORE RESERVED...AT LEAST THROUGH 09Z.
SOME POTENTIAL FOR FOG ACROSS THE NORTHEAST OVERNIGHT AS REMAINING
CLOUDS ACROSS THE AREA DISSIPATE WITH SUNSET AND SURFACE RIDGING
MOVES OVERHEAD PRODUCING LIGHT WIND. NOT LOOKING AT DENSE FOG AT
THIS POINT GIVEN THE VERY SHALLOW NATURE OF THE MOISTURE MOVING IN.
GENERALLY WENT WITH PATCHY FOG WORDING HOWEVER ALO/MCW WILL BE EAST
OF THE RIDGE AXIS AND MOISTURE COULD BE ENOUGH FOR A LITTLE MORE
WIDESPREAD FOG SO I MENTION AREAS OF FOG OVER THESE LOCATIONS.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 305 PM CDT TUE AUG 19 2014
A BREAK IN THE CONVECTION IS EXPECTED ON WED AS THE FIRST ROUND OF
THETA-E ADVECTON LIFTS OUT OF THE STATE. A RENEWED THREAT OF
THUNDERSTORMS WILL COME AS THE WARM FRONT LIFTS NORTH AND STRONG
THETA-E ADVECTION TAKES PLACE WED NIGHT. THE H8 SHOWS GOOD SPEED
CONVERGENCE AND THERE IS DIVERGENCE ALOFT...THE FLY IN THE
OINTMENT WILL BE IF THE ATMOSPHERE CAPS OFF OR NOT. AN EML IS IN
PLACE...BUT IT IS NOT ALL THAT STRONG.
WARM AND HUMID WEATHER WILL HOLD INTO THE WEEKEND WITH AFTERNOON
HEAT INDICES IN THE LOW TO MID 90S NORTH...AND 95 TO 105 SOUTH
TUE-THU AFTERNOON. BELOW CRITERIA...BUT WILL MENTION IN THE HWO
WITH ALL THE SCHOOL ACTIVITIES GOING ON.
COOLER WEATHER WILL MOVE IN OVER THE WEEKEND...FIRST DUE TO THE
INCREASED CLOUD COVER...THEN DUE TO THE FRONTAL PASSAGE SAT. COOL
AIR WILL SETTLE IN SLOWLY WITH TEMPS FALLING BELOW NORMAL; FOR MON
AND TUE.
&&
.AVIATION...19/18Z
ISSUED AT 1247 PM CDT TUE AUG 19 2014
WARMER AIR WILL MOVE INTO CENTRAL IOWA FROM THE SW...ALONG WITH SOME
MOISTURE AND INSTABILITY AS A WARM FRONT TRIES TO ESTABLISH ITSELF
OVER NEB AND KS THEN LIFT INTO IA LATER THIS EVENING/OVERNIGHT.
SOME SHOWERS/TSRA ARE POSSIBLE MAINLY FM KDSM-KOTM BUT MAY MAKE IT
AS FAR NORTH AS KFOD. WITH LOW LEVEL MOISTURE INCREASING...COULD
ALSO SEE SOME FOG...ESPECIALLY NORTHEAST AFT 08Z. MVFR VSBYS
POSSIBLE IN THE FOG. VFR CONDITIONS SHOULD AGAIN PREVAIL AFTER 13-
15Z.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MS AUG 14
SHORT TERM...FAB
LONG TERM...MS AUG 14
AVIATION...FAB
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
1235 AM CDT Tue Aug 19 2014
...Updated for Aviation...
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 1202 PM CDT MON AUG 18 2014
There is a high pressure ridge over Colorado south into New Mexico
late this afternoon. A lee side trough is near the Kansas and
Colorado border, and a warm front has been pushing northeast
through western Kansas this morning. The forecast is on track for
today, with highs just over 100F degrees likely somewhere across
southern and western Kansas, and upper 90s in our northern zones.
There could be a few and far between showers and isolated
thunderstorms just about anywhere late today. The HRRR model shows
a few thunderstorms across our south and southeast zones after
21z, but the NAM and NAMNG5 models are showing storms first over
our west and then moving across the northern CWA. Mid and high
clouds will be on the increase late this afternoon and evening.
So, the low Pops in the 17-20 percent range blanketing our
forecast area seem reasonable. Time will tell on which model is
more correct.
The same HRRR, NAM, and NAMNG5 models decrease the measurable
precip after 04Z, and then the clouds will slowly dissipate after
09Z or so. I plan to reduce 20 percent Pops rapidly between 06Z and
12Z. Not much precipitation will fall either, as any convection
will be high based. I used the QPF_from_PoP application, and it
only shows 0.01 to spotty 0.03 inches of rain overnight. With
clouds breaking late and perhaps a little rain, minimum temperatures
should end up in the middle 60s in Syracuse, Scott City, and
Wakeeney, while settling only to around 70F degrees in the Meade,
Coldwater and Medicine Lodge areas. Winds will continue to hover
at less than 10 MPH tonight.
On Tuesday, the surface low will advect into central Kansas, and the
front will sag south across part of our CWA. Thus, Max temps should
dip just a little north of the front, while south along the Oklahoma
border near Medicine Lodge, it should warm up to around 100F. Winds
on Tuesday will be breezy from the south in the 15 to 25 mph and
gusty range. I do not think there will any precipitation on
Tuesday, as the lower max temps will result in less instability than
today.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 225 PM CDT MON AUG 18 2014
Medium range models indicate an upper level ridge of high pressure
transitioning eastward out of the Western High Plains into the
Central Plains to begin the period Tuesday night. Combined with
a weak flow aloft, drier conditions are likely to prevail through
late Wednesday afternoon. Meanwhile, an upper level trough will dig
southeast across southern California Wednesday setting up a strong
southwest flow aloft across the Central and Southern Rockies,
including a +90kt jet core projected to lift northeast out of the
Desert Southwest into the Colorado Rockies. With a prevailing lee
side trough providing increased convergence in the lower levels,
thunderstorm development is likely across portions of eastern
Colorado Wednesday afternoon with a few storms potentially
drifting into western Kansas later in the evening through early
Thursday. However, the weaker flow aloft across western Kansas
will limit the strength and coverage of any storms. The upper
level shortwave will then lift northeast going into the weekend
while a large scale upper level high remains locked in across the
Deep South. Although precip chances will remain present virtually
each day into the weekend, the weaker flow aloft will limit storm
development, strength, and coverage.
Temperatures will remain above normal Wednesday as the
aforementioned upper level ridge shifts east across the Central
Plains. A prevailing southerly flow across western Kansas will
reinforce the warmer air mass already in place across the region
with H85 temperatures ranging from the upper 20s(C) in central
Kansas to around 30C closer to the Colorado border. As lower level
lapse rates steepen into the afternoon, look for highs well up
into the 90s(F) to near 100F Wednesday. Similar temperatures are
then expected each day through Saturday as the low level southerly
flow persists into the early part of the weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1232 AM CDT TUE AUG 19 2014
A few showers and isolated thunderstorms will dissipate by 07-09Z
this morning. A lee trough of low pressure will deepen with south
winds increasing to 15-25kt after 18Z. VFR conditions are expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 71 99 74 100 / 0 10 10 10
GCK 70 98 70 100 / 0 10 10 10
EHA 69 98 68 97 / 10 20 20 20
LBL 70 98 71 100 / 0 10 10 10
HYS 71 99 73 98 / 0 10 20 20
P28 74 99 76 100 / 0 10 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Burke
LONG TERM...JJohnson
AVIATION...Kruse
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1136 PM CDT Mon Aug 18 2014
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Tuesday)
Issued at 352 PM CDT MON AUG 18 2014
The center of an upper level trough was located across eastern ND
late this afternoon with an upper level trough axis extending
southwest across central SD. The numerical models show this upper
level trough digging southeast across southern MN and eastern NE
into northern MO. The southwest section of the upper trough will
move southeast across northeast KS between 6Z and 12Z. The NAM,
GFS and ECMWF forecast QPF across northeast and east central KS
later Tonight, with the ECMWF and NAM showing most of the CWA with
QPF. The NAM model shows weak isentropic lift at the 310K level
with LFCs around 700mb. The most intense isentropic lift at the
310K level will be across northern MO and IA.
The mesoscale models, consisting of the ARW, NMM and HRRR do not
forecast any QPF across the CWA tonight. I will probably keep slight
chance to chance pops across much of the CWA, since the ascent ahead
of the H5 trough combined with isentropic lift should allow elevated
thunderstorms to develop across the northeast counties of the CWA
around midnight, then building southwest across the central and
southwest counties of the CWA through the early morning hours before
spreading southeast across much of east central KS by 12Z TUE.
Any lingering elevated thunderstorms, if they do develop, will shift
southeast of the CWA during the mid morning hours. Skies should
clear through the late morning and early afternoon hours and
temperatures will warm into the lower to mid 90s. If there is a
leftover outflow boundary across the northeast counties, then
temperatures along the NE border may only reach into the upper 80s.
I placed in 14 pops in case there is enough surface convergence for
an isolated thunderstorm during the afternoon hours.
.LONG TERM...(Tuesday Night through Monday)
Issued at 352 PM CDT MON AUG 18 2014
Models are in agreement that heights rises and resulting warm air
advection will be situated across the northeast corner of the county
warning area Tuesday evening providing another chance for
thunderstorms. As this area focuses further northward through the
night...have removed pops this area after midnight. Will keep lows
mild in the low to middle 70s. This will then set the stage for
mostly sunny very warm...breezy day on Wednesday. Highs will
generally be 95 to 100 degrees with the warmest in the Abilene area
and the coolest near Hiawatha.
As the upper ridge builds across the southern plains...expect dry
weather across the cwa Wednesday night through Thursday. However...
with south winds continuing...highs Thursday will again be in the
middle to upper 90s.
As the cutoff upper trough in the desert southwest gets picked up by
Thursday and heads into the central and northern high plains into
the weekend...there will be better chances for thunderstorms across
the area...although the northern/northwest 1/2 of the cwa will be
the more likely areas to see rain. Do not expect a frontal passage
until during the day Sunday...so may not see highs temps below 90
degrees until Monday when readings in the middle to upper 80s should
be the rule.
&&
.AVIATION...(For the 06Z TAFs through 06Z Tuesday Night)
Issued at 1119 PM CDT MON AUG 18 2014
VFR prevails at KTOP/KFOE/KMHK with main concern being TSRA
potential. Cluster of TSRA over north central KS is progged to
gradually dissipate towards the southeast overnight. Short term
guidance maintains scattered TSRA aft 08Z so will leave VCTS
mention through 11Z at KMHK and 14Z at KTOP/KFOE.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...63
AVIATION...Bowen
AREA FORECAST DISCUSSION
NWS PADUCAH KY
ISSUED BY NATIONAL WEATHER SERVICE LOUISVILLE KY
1250 PM CDT Tue Aug 19 2014
.UPDATE...
Issued at 1250 PM CDT TUE AUG 19 2014
The AVIATION section has been updated for the 18Z TAF issuance.
UPDATE Issued at 1121 AM CDT TUE AUG 19 2014
The fog and low clouds have dissipate, leaving behind just a
scattered cu deck late this morning.
An area of convection has weakened significantly since 15Z as it
moved eastward into the KSTL area. However, it did push an outflow
boundary eastward and it is only a county or so northwest of our
area as of 16Z. Not sure whether the boundary will survive as it
moves into the strong mixing in our region or not, but figure it
or just a differential heating boundary may focus thunderstorm
development possibly by 18Z in the KMVN and KMDH areas.
The latest HRRR and 12Z NAM runs develop convection over much of
southern Illinois and push it southeast through southwest Indiana
and much of west Kentucky through the late afternoon and early
evening hours. The southwestward extent of development is in doubt
due to a very strong capping inversion noted on the 12Z KSGF RAOB.
The forecast has been updated to account for these convective
trends. Capped PoPs in the northeast at 50% due to the potential
for the cap to hold even up there. Also, kept a slight chance in
the far west just in case the cap does not hold. The NAM soundings
indicate that there will be some fairly steep mid-level lapse
rates for storms to feed on, if the cap can be broken. Wind fields
will be increasing, but the best winds may lag the convection
through the area. Given the instability alone, figure that a few
storms will reach severe criteria with winds and hail the primary
concerns.
&&
.SHORT TERM...(Today through Thursday night)
Issued at 214 AM CDT TUE AUG 19 2014
Short term weather continues to be somewhat active.
Aside from patchy/areas of dense fog early this morning, only a few
high clouds are expected to track across the region. An MCS located
over north central Kansas at the time of this writing should weaken
considerably on its southeast trek, and should there be anything
left of it later this morning, it should pass by to our south and
west.
Precipitation chances are expected to make their way into the
forecast this afternoon as a short wave pushes a weak cold front
toward the lower Ohio valley. Due to lack of deeper moisture models
not showing much in the way of convection before 18Z, but after that
precipitation chances should begin to increase from the northwest
with the approach of the aforementioned boundary. With decent flow
aloft over a moderately unstable airmass in place, a few storms
could become strong to severe Tuesday afternoon into the evening
hours, especially over most of southern Illinois and northwest
Kentucky, and all of southwest Indiana. Large hail and damaging
winds will be the primary threats.
Models show the short wave outrunning the surface boundary late
Tuesday night, and with H5 heights beginning to increase at that
point, the boundary never quite makes it into our CWA and gets
pushed back to the north and east as a warm front.
Precipitation chances will begin to diminish from southwest to
northeast on Wednesday as an upper ridge over the southern plains
begins to build northeast across our region . This trend will
continue through Thursday as the ridge continues to overspread the
area. At this time it looks like Thursday night will be dry as the
upper ridge takes control.
Unfortunately with the approach of the ridge, the resultant
compression/warming of the air will raise temperatures to near
normal levels (mid 90s) the latter half of the short term period.
This combined with dewpoints around 70 degrees will produce heat
indices near the century mark for most if not all of our CWA both
Wednesday and Thursday afternoon.
.LONG TERM...(Friday through Monday)
Issued at 214 AM CDT TUE AUG 19 2014
The long term will be dominated by an upper level ridge over the
Lower and Middle Mississippi Valley. This will help to stabilize the
atmosphere as the tropospheric profile undergoes a drying trend.
Consequently, any slight chance for showers and thunderstorms will
likely be shunted north and east of the immediate forecast area
through the weekend.
The main concern during this time will be the heat and humidity as
the hottest weather of the year takes hold. Highs in the mid to
upper 90s will combine with relatively high humidity to push heat
index readings to the 100 to 105 degree range each afternoon. Given
the anticipated prolonged nature of this event, I see little reason
why a Heat Advisory will not be issued later this week for peak
afternoon heat indices between 100 and 105 for at least four
consecutive days. Will continue to monitor and adjust forecast as
necessary.
&&
.AVIATION...
Issued at 1250 PM CDT TUE AUG 19 2014
An outflow boundary is expected to provide a focus for
thunderstorm development over southern Illinois this afternoon.
Best guess is that the storms would impact KEVV and KOWB around
00Z. With plentiful low-level moisture, fog development will be
possible again tonight, but with some southwest wind expected,
LIFR/VLIFR conditions are less likely. If they occur it would most
likely be at KCGI. Just a few cu expected by midday Wednesday,
along with modest west southwest to west winds.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...DRS
SHORT TERM...JP
LONG TERM...RJP
AVIATION...DRS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1239 AM EDT TUE AUG 19 2014
.UPDATE...
ISSUED AT 1130 PM EDT MON AUG 18 2014
UPDATED THE FORECAST TO ISSUE A DENSE FOG ADVISORY FOR EASTERN
KENTUCKY. HAD REPORTS OF DENSE FOG MOST OF THE WAY FROM CLAY CITY TO
JACKSON. AT SIGNS POINT TO A WIDESPREAD FOG EVENT TONIGHT THAT IS
WORSE THAN THE NORMAL AUGUST VALLEY FOG.
UPDATE ISSUED AT 702 PM EDT MON AUG 18 2014
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. THE PRECIPITATION HAS BEEN TAPERING OFF AS THE SHORT WAVE
MOVES OFF TO THE EAST. LOWERED THE PROBABILITY OF PRECIPITATION
BASED ON CURRENT RADAR AND THE LATEST HRRR OUTPUT. ALSO TOOK OUT THE
CHANCE OF THUNDER OUT AS NONE HAS DEVELOPED ALL DAY AND THE MODELS
ARE NOT SUPPORTING THEIR DEVELOPMENT IN THE NEAR TERM. THE ONLY
THUNDER IS CURRENTLY OVER CENTRAL TENNESSEE. A WEAK FRONT IS STILL
QUASI STATIONARY OVER THE AREA. EXPECT TO SEE SOME FAIRLY DENSE FOG
TONIGHT...ESPECIALLY IN THE VALLEYS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 255 PM EDT MON AUG 18 2014
THE LOW PRESSURE SYSTEM THAT BROUGHT THE WIDESPREAD RAIN LAST NIGHT
INTO THIS MORNING HAS MOVED INTO WV...TAKING THE DEEPER MOISTURE AND
BETTER LIFT WITH IT. A WEST EAST ORIENTED QUASI STATIONARY FRONT
REMAINS ACROSS KENTUCKY...AND SCATTERED LIGHT SHOWERS CONTINUE TO
MOVE FROM WEST TO EAST ACROSS THE AREA. ANOTHER WAVE OF LOW PRESSURE
EVIDENT ON SATELLITE AND RADAR IMAGERY WAS MOVING EAST ALONG THE TN MS
BORDER. THIS FEATURE...ALONG WITH THE BOUNDARY ACROSS KY WILL
NECESSITATE CONTINUING WITH A CHANCE OF RAIN OVERNIGHT. HOWEVER THE
BEST RAIN AND THUNDER CHANCES SHOULD BE SOUTH OF KY TONIGHT.
WITH VERY MOIST BOUNDARY LAYER AND SOME BREAKS EXPECTED IN THE CLOUDS
THIS EVENING...FOG AND LOW CLOUDS ARE EXPECTED TO DEVELOP DURING THE
NIGHT AND LINGER INTO THE MORNING ON TUESDAY. WILL INCLUDE FOG IN THE
FORECAST FOR TONIGHT. ON TUESDAY THE NEXT SHORT WAVE IN THIS VERY
ACTIVE PATTERN WILL BE PUSHING INTO THE WESTERN GREAT LAKES REGION. AT
THE SURFACE A VERY MOIST AND WARM AIR MASS WILL REMAIN IN PLACE
ACROSS EASTERN KY ON TUESDAY...WHILE A COLD FRONT DROPS SOUTHEAST ACROSS IL
AND INDIANA. THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF THIS
FRONT TUESDAY AFTERNOON. CURRENT THINKING IS THAT SHOWERS AND
THUNDERSTORMS THAT DEVELOP TO OUR NORTHWEST ON TUESDAY WILL MOVE INTO
OUR AREA TUESDAY NIGHT. WITH THIS THOUGHT IN MIND WILL INTRODUCE
LIKELY PROBABILITIES FOR SHOWERS AND THUNDERSTORMS IN THE NORTHERN
PART OF OUR FORECAST AREA TUESDAY NIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 255 PM EDT MON AUG 18 2014
MODELS CONTINUE TO DISPLAY GOOD AGREEMENT THROUGH THE EXTENDED.
UPPER/MID LEVEL GREAT LAKES LOW WILL MAKE A BEE LINE TO THE MID
ATLANTIC COAST BY FRIDAY. MEANWHILE BURGEONING RIDGE TO OUR WEST
WILL EXERT ITS INFLUENCE FROM THE SOUTHERN PLAINS/MISSISSIPPI RIVER
DELTA NORTHWARD INTO THE UPPER MIDWEST. GREAT LAKES LOW WILL PASS TO
OUR NORTHEAST DURING ITS MARCH TO THE COAST AND DRAG A SURFACE
FRONTAL BOUNDARY ACROSS THE CENTER OF THE OHIO VALLEY REGION.
SHARPENING UPPER LEVEL RIDGE AXIS WILL SHIFT SOUTHEASTWARD OVER OUR
AREA TOWARDS THE END OF THE EXTENDED AS ENERGY ROUNDS ITS TOP ACROSS
THE NORTHERN TIER. DESPITE THE BUILDING RIDGE ALOFT...THE BY THEN
QUASI-STATIONARY SFC FRONTAL BOUNDARY WILL REMAIN IN OUR VICINITY AS
IT BECOMES ORIENTED PARALLEL TO THE UPPER LEVEL FLOW PATTERN. THUS
WITH LITTLE TO NO FORCING AT THE MID AND UPPER LEVELS...THIS
BOUNDARY WILL REMAIN CLOSE ENOUGH TO OUR AREA TO SERVE AS A FOCUS
FOR ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY THROUGH THE LATTER
HALF OF THE EXTENDED PERIOD. THE MAINLY DIURNAL SHOWER AND
THUNDERSTORM ACTIVITY MAY BE AUGMENTED BY ONE OR TWO ORGANIZED
THUNDERSTORM COMPLEXES DROPPING DOWN FROM THE NORTHWEST ON THE EAST
SIDE OF THE UPPER RIDGE.
FOR SENSIBLE WEATHER...WE WILL SEE THE RETURN OF TRUE SUMMER LIKE
WEATHER AS RIDGING TO OUR SOUTHWEST WILL BE STRONG ENOUGH TO SEND
TEMPERATURES INTO AND ABOVE SEASONABLE NORMS DESPITE THE INCREASED
HUMIDITY. THIS WILL ALSO HELP TO ENHANCE THE DIURNALLY DRIVEN
INSTABILITY ACROSS THE AREA RESULTING IN THE BEST CHANCES OF STORMS
EACH AFTERNOON AND EVENING. THE THREAT OF RAIN DECREASES BY NEXT
WEEKEND AS THE UPPER RIDGE AMPLIFIES AND SHIFTS EASTWARD A BIT...BUT
THE POTENTIAL CAN NOT BE TOTALLY REMOVED. IN ADDITION...SHOULD THE
RIDGE EXERT A STRONGER INFLUENCE BY SHIFTING JUST A BIT MORE EAST WE
MAY BE IN FOR EVEN HOTTER WEATHER BY NEXT WEEKEND. WITH THE 0Z ECMWF
ADVERTISING H850 TEMPS UP AROUND 22C TO 24C...THE POSSIBLY EXISTS
THAT WE MIGHT SEE SOME OF OUR HOTTEST WEATHER OF THE SUMMER THUS
FAR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1239 AM EDT TUE AUG 19 2014
THE MAIN CONCERN FOR THE FIRST 6 HOURS OF THE TAF PERIOD WILL BE LOW
CEILINGS AND FOG ACROSS EASTERN KENTUCKY. PARTLY CLOUD SKIES ALONG
WITH LIGHT WINDS AND PLENTY OF RAINFALL DURING THE PRIOR DAY HAS LEFT
A MOIST AND VERY STABLE BOUNDARY LAYER FOR FOG DEVELOPMENT. A FEW
SHOWERS MAY DEVELOP OVERNIGHT BUT WILL BE ISOLATED. HEADING INTO THE
DAY...SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL BE POSSIBLE AND
KSYM MAY NEED A VCTS MENTION AS THE BEST CHANCE FOR SHOWERS AND
STORMS WILL BE IN THE NORTH. OTHERWISE...EXPECT LIGHT WINDS AND
DECKS AROUND 5 KFT AFTER THE FOG LIFTS TODAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ044-
050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...JJ
SHORT TERM...SBH
LONG TERM...RAY
AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
106 PM CDT TUE AUG 19 2014
.AVIATION...
FOR THE 19/18Z TAFS...SCATTERED CONVECTION BEGINNING TO DEVELOP IN
ASSOCIATION WITH A WEAK SHEAR AXIS AND MID LVL TROUGH OVER CNTRL
TX. HAVE VCTS AREAWIDE THIS AFTERNOON BUT SHWRS/TSTMS SHOULD BE
MOSTLY UNORGANIZED AND SPOTTY. WITH THE EXCEPTION OF KLFK...DIRECT
IMPACTS ON THE TAF SITES ARE TOO UNCERTAIN TO PREVAIL OR TEMPO PRECIP
SO AMENDMENTS MAY BE NEEDED LATER THIS AFTERNOON. VFR CONDITIONS
SHOULD PREVAIL ALTHOUGH MVFR OR LOWER CONDITIONS WILL BE POSSIBLE
WHERE CONVECTION IS ONGOING. SHWRS/TSTMS EXPECTED TO SLOWLY
DISSIPATE AFTER SUNSET WITH THE LOSS OF DAYTIME HEATING. MOIST SLY
FLOW SHOULD RESULT IN A BRIEF WINDOW OF LOW STRATUS AROUND SUNRISE
WEDNESDAY MORNING MAINLY ALONG AND SOUTH OF I-20 WITH CIGS LIFTING
LATE IN THE PERIOD. /09/
&&
.PREV DISCUSSION... /ISSUED 1109 AM CDT TUE AUG 19 2014/
DISCUSSION...
HAVE BUMPED UP THE DAYTIME HIGHS FOR MUCH OF THE FOUR STATE AREA
TODAY GIVEN THE CURRENT TREND SHOWS WARMING ABOUT 2 TO 3 DEGREES
FASTER TODAY THAN YESTERDAY. MINOR ADJUSTMENTS TO THE DEW POINTS AND
WINDS. NO OTHER SIGNIFICANT CHANGES TO THE FORECAST. /06/
PREV DISCUSSION... /ISSUED 423 AM CDT TUE AUG 19 2014/
DISCUSSION...
THE MORNING WATER VAPOR IMAGERY INDICATES THAT THE MAIN SHORTWAVE
THAT PRODUCED EXTENSIVE CONVECTION JUST 24 HRS AGO OVER SW
AR/EXTREME NRN LA HAS SHIFTED E INTO NRN GA...WITH THE 00Z RAOB
500MB PLOT STILL REVEALING A WEAK SHEAR AXIS THAT EXTENDS FARTHER
W ACROSS NRN MS/N LA AND INTO NE TX. MEANWHILE...MOSAIC RADAR
IMAGERY ALSO INDICATES A WELL-DEFINED MCV SPINNING E OF
SJT...WHICH THE 00Z PROGS HAVE INITILIZED WELL ON AS CONVECTION
CONTINUES TO REGENERATE NEAR AND E OF THE CENTER OVER CNTRL TX.
THIS CONVECTION HAS PRODUCED A THICK AC CANOPY OVER NE TX/EXTREME
NW LA...ALTHOUGH IR IMAGERY DEPICTS WARMING CLOUD TOPS SUGGESTING
A WEAKENING TREND IS ONGOING ATTM. THIS MCV CENTER IS PROGGED TO
DRIFT NNE ACROSS NCNTRL TX TODAY...WHICH COULD MAINTAIN ELEVATED
CONVECTIVE DEBRIS OVER THE NRN HALF OF THE AREA THROUGH AT LEAST
THE FIRST HALF OF THE DAY...BEFORE POSSIBLY THINNING THIS
AFTERNOON. MY FORECAST MAX TEMPS MAY BE A BIT HIGH TODAY
ESPECIALLY IF THIS DEBRIS FIELD HANGS TOUGH TODAY...BUT HAVE
PLAYED THE PESSIMIST WITH IT THINNING LATER TODAY...ESPECIALLY AS
09Z TEMPS REMAIN IN THE MID/UPPER 70S. WHILE THE SHORT TERM PROGS
DO SUGGEST A WEAK SEABREEZE AFFECTING DEEP E TX/SRN SECTIONS OF
NCNTRL LA THIS AFTERNOON...ONLY THE LATEST HRRR RUN DEPICTS AT
LEAST ISOLATED CONVECTION DEVELOPING THIS AFTERNOON ALONG THE
RESIDUAL SHEAR AXIS...WHICH IS STILL WEAKLY REFLECTED IN THE OTHER
SHORT RANGE PROGS. IN ADDITION...THE 09Z SFC ANALYSIS INDICATES A
DISTINCT W-E GRADIENT IN SFC THETA-E FROM NEAR OSA TO ALONG THE
AR/LA LINE...INDICATIVE OF THE WEAK COLD POOL FROM CONVECTION THAT
AFFECTED THESE AREAS MONDAY AFTERNOON/EVENING. GIVEN THESE WEAK
SFC AND UPPER AIR FORCING MECHINISMS...AND THE FACT THAT THE CNTRL
TX MCV IS PROGGED TO LIFT NNE ACROSS THE STATE TODAY...HAVE
EXPANDED SLIGHT CHANCE POPS TO COVER MUCH OF THE REGION THIS
AFTERNOON...AND DID CARRY THEM THROUGH THE EVENING BEFORE THEY
DIMINISH WITH THE STABILIZING BNDRY LYR.
THE SHEAR AXIS IS EXPECTED TO WASH OUT OVERNIGHT WITH THE MCV
OPENING UP LATE...AS THE WRN ATLANTIC/CNTRL GULF OF MX UPPER RIDGE
EXPECTED TO BRIDGE NWD INTO THE LOWER MS VALLEY WEDNESDAY. STILL
SHOULD SEE A WEAK SEABREEZE AFFECTING THE SRN ZONES WEDNESDAY AND
THURSDAY AFTERNOONS/EARLY EVENINGS...BEFORE THE UPPER RIDGE CENTER
BECOMES ESTABLISHED OVER THE MID-SOUTH/LOWER MS VALLEY FRIDAY.
BOTH THE GFS AND ECMWF AMPLIFY THE RIDGE FARTHER N ACROSS THE SRN
PLAINS/MS VALLEY FRIDAY...AND KEEPS IT PERSISTENT THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. INCREASED SUBSIDENCE WILL RESULT IN
MAX TEMPS CLIMBS INTO THE UPPER 90S AREAWIDE...WITH EVEN SOME
TRIPLE DIGITS POSSIBLE OVER SOME AREAS THIS WEEKEND/EARLY NEXT
WEEK. THE MEDIUM RANGE PROGS DO BEGIN TO SLOWLY NUDGE THE RIDGE E
INTO THE SE STATES BY TUESDAY/WEDNESDAY...WITH WEAKNESSES RIDING W
BENEATH THE RIDGE ACROSS S LA/SRN MS AS EARLY AS MONDAY.
THUS...ISOLATED CONVECTION WILL BE POSSIBLE OVER NCNTRL LA MONDAY
AFTERNOON...BEFORE SPREADING FARTHER WNW TO ENCOMPASS MUCH OF THE
REGION BY THE END OF THE EXTENDED.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 95 75 96 76 97 / 10 10 10 10 10
MLU 95 73 96 74 97 / 20 20 10 10 10
DEQ 94 71 94 71 95 / 20 20 0 0 0
TXK 94 74 96 74 96 / 20 20 0 0 0
ELD 95 72 96 74 97 / 20 20 0 0 0
TYR 95 75 96 76 97 / 10 20 10 10 10
GGG 95 74 96 75 97 / 10 10 10 10 10
LFK 96 75 96 76 97 / 20 20 20 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
09
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1109 AM CDT TUE AUG 19 2014
.DISCUSSION...
HAVE BUMPED UP THE DAYTIME HIGHS FOR MUCH OF THE FOUR STATE AREA
TODAY GIVEN THE CURRENT TREND SHOWS WARMING ABOUT 2 TO 3 DEGREES
FASTER TODAY THAN YESTERDAY. MINOR ADJUSTMENTS TO THE DEW POINTS AND
WINDS. NO OTHER SIGNIFICANT CHANGES TO THE FORECAST. /06/
&&
.PREV DISCUSSION... /ISSUED 651 AM CDT TUE AUG 19 2014/
AVIATION...
CONCERNING THE ARKLATEX...A LOT OF DEBRIS CIRRUS KEEPING STATION
AND MITIGATING MVFR BOTH CIGS/FG. CONVECTION TODAY MAY OCCUR OVER
THE SOUTH WITH RESPECT TO A WEAK SEA BREEZE PUSH AND OVER OUR
NORTH ALONG A WEAK SHEAR AXIS WITH SOMEWHAT BETTER CHANCES FROM
KTXK...TO KMLU AND MAY BRIEFLY AFFECT KELD AND KSHV THIS
MID AFTERNOON BASED ON THE HIGH RES MODEL. VCTS FOR THE AFTERNOON
HOURS WILL BE AMENDED WITH DEVELOPMENT. OTHERWISE S/SW WINDS ON
THE SFC ARE GENERALLY SW- NW ALOFT WITH NOT MUCH SPEED ANYWHERE.
/24/
PREV DISCUSSION... /ISSUED 423 AM CDT TUE AUG 19 2014/
DISCUSSION...
THE MORNING WATER VAPOR IMAGERY INDICATES THAT THE MAIN SHORTWAVE
THAT PRODUCED EXTENSIVE CONVECTION JUST 24 HRS AGO OVER SW
AR/EXTREME NRN LA HAS SHIFTED E INTO NRN GA...WITH THE 00Z RAOB
500MB PLOT STILL REVEALING A WEAK SHEAR AXIS THAT EXTENDS FARTHER
W ACROSS NRN MS/N LA AND INTO NE TX. MEANWHILE...MOSAIC RADAR
IMAGERY ALSO INDICATES A WELL-DEFINED MCV SPINNING E OF
SJT...WHICH THE 00Z PROGS HAVE INITILIZED WELL ON AS CONVECTION
CONTINUES TO REGENERATE NEAR AND E OF THE CENTER OVER CNTRL TX.
THIS CONVECTION HAS PRODUCED A THICK AC CANOPY OVER NE TX/EXTREME
NW LA...ALTHOUGH IR IMAGERY DEPICTS WARMING CLOUD TOPS SUGGESTING
A WEAKENING TREND IS ONGOING ATTM. THIS MCV CENTER IS PROGGED TO
DRIFT NNE ACROSS NCNTRL TX TODAY...WHICH COULD MAINTAIN ELEVATED
CONVECTIVE DEBRIS OVER THE NRN HALF OF THE AREA THROUGH AT LEAST
THE FIRST HALF OF THE DAY...BEFORE POSSIBLY THINNING THIS
AFTERNOON. MY FORECAST MAX TEMPS MAY BE A BIT HIGH TODAY
ESPECIALLY IF THIS DEBRIS FIELD HANGS TOUGH TODAY...BUT HAVE
PLAYED THE PESSIMIST WITH IT THINNING LATER TODAY...ESPECIALLY AS
09Z TEMPS REMAIN IN THE MID/UPPER 70S. WHILE THE SHORT TERM PROGS
DO SUGGEST A WEAK SEABREEZE AFFECTING DEEP E TX/SRN SECTIONS OF
NCNTRL LA THIS AFTERNOON...ONLY THE LATEST HRRR RUN DEPICTS AT
LEAST ISOLATED CONVECTION DEVELOPING THIS AFTERNOON ALONG THE
RESIDUAL SHEAR AXIS...WHICH IS STILL WEAKLY REFLECTED IN THE OTHER
SHORT RANGE PROGS. IN ADDITION...THE 09Z SFC ANALYSIS INDICATES A
DISTINCT W-E GRADIENT IN SFC THETA-E FROM NEAR OSA TO ALONG THE
AR/LA LINE...INDICATIVE OF THE WEAK COLD POOL FROM CONVECTION THAT
AFFECTED THESE AREAS MONDAY AFTERNOON/EVENING. GIVEN THESE WEAK
SFC AND UPPER AIR FORCING MECHINISMS...AND THE FACT THAT THE CNTRL
TX MCV IS PROGGED TO LIFT NNE ACROSS THE STATE TODAY...HAVE
EXPANDED SLIGHT CHANCE POPS TO COVER MUCH OF THE REGION THIS
AFTERNOON...AND DID CARRY THEM THROUGH THE EVENING BEFORE THEY
DIMINISH WITH THE STABILIZING BNDRY LYR.
THE SHEAR AXIS IS EXPECTED TO WASH OUT OVERNIGHT WITH THE MCV
OPENING UP LATE...AS THE WRN ATLANTIC/CNTRL GULF OF MX UPPER RIDGE
EXPECTED TO BRIDGE NWD INTO THE LOWER MS VALLEY WEDNESDAY. STILL
SHOULD SEE A WEAK SEABREEZE AFFECTING THE SRN ZONES WEDNESDAY AND
THURSDAY AFTERNOONS/EARLY EVENINGS...BEFORE THE UPPER RIDGE CENTER
BECOMES ESTABLISHED OVER THE MID-SOUTH/LOWER MS VALLEY FRIDAY.
BOTH THE GFS AND ECMWF AMPLIFY THE RIDGE FARTHER N ACROSS THE SRN
PLAINS/MS VALLEY FRIDAY...AND KEEPS IT PERSISTENT THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. INCREASED SUBSIDENCE WILL RESULT IN
MAX TEMPS CLIMBS INTO THE UPPER 90S AREAWIDE...WITH EVEN SOME
TRIPLE DIGITS POSSIBLE OVER SOME AREAS THIS WEEKEND/EARLY NEXT
WEEK. THE MEDIUM RANGE PROGS DO BEGIN TO SLOWLY NUDGE THE RIDGE E
INTO THE SE STATES BY TUESDAY/WEDNESDAY...WITH WEAKNESSES RIDING W
BENEATH THE RIDGE ACROSS S LA/SRN MS AS EARLY AS MONDAY.
THUS...ISOLATED CONVECTION WILL BE POSSIBLE OVER NCNTRL LA MONDAY
AFTERNOON...BEFORE SPREADING FARTHER WNW TO ENCOMPASS MUCH OF THE
REGION BY THE END OF THE EXTENDED.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 95 75 96 76 97 / 10 10 10 10 10
MLU 95 73 96 74 97 / 20 20 10 10 10
DEQ 94 71 94 71 95 / 20 20 0 0 0
TXK 94 74 96 74 96 / 20 20 0 0 0
ELD 95 72 96 74 97 / 20 20 0 0 0
TYR 95 75 96 76 97 / 10 20 10 10 10
GGG 95 74 96 75 97 / 10 10 10 10 10
LFK 96 75 96 76 97 / 20 20 20 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
06
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
651 AM CDT TUE AUG 19 2014
.AVIATION...
CONCERNING THE ARKLATEX...A LOT OF DEBRIS CIRRUS KEEPING STATION
AND MITIGATING MVFR BOTH CIGS/FG. CONVECTION TODAY MAY OCCUR OVER
THE SOUTH WITH RESPECT TO A WEAK SEA BREEZE PUSH AND OVER OUR
NORTH ALONG A WEAK SHEAR AXIS WITH SOMEWHAT BETTER CHANCES FROM
KTXK...TO KMLU AND MAY BRIEFLY AFFECT KELD AND KSHV THIS
MID AFTERNOON BASED ON THE HIGH RES MODEL. VCTS FOR THE AFTERNOON
HOURS WILL BE AMENDED WITH DEVELOPMENT. OTHERWISE S/SW WINDS ON
THE SFC ARE GENERALLY SW- NW ALOFT WITH NOT MUCH SPEED ANYWHERE.
/24/
&&
.PREV DISCUSSION... /ISSUED 423 AM CDT TUE AUG 19 2014/
DISCUSSION...
THE MORNING WATER VAPOR IMAGERY INDICATES THAT THE MAIN SHORTWAVE
THAT PRODUCED EXTENSIVE CONVECTION JUST 24 HRS AGO OVER SW
AR/EXTREME NRN LA HAS SHIFTED E INTO NRN GA...WITH THE 00Z RAOB
500MB PLOT STILL REVEALING A WEAK SHEAR AXIS THAT EXTENDS FARTHER
W ACROSS NRN MS/N LA AND INTO NE TX. MEANWHILE...MOSAIC RADAR
IMAGERY ALSO INDICATES A WELL-DEFINED MCV SPINNING E OF
SJT...WHICH THE 00Z PROGS HAVE INITILIZED WELL ON AS CONVECTION
CONTINUES TO REGENERATE NEAR AND E OF THE CENTER OVER CNTRL TX.
THIS CONVECTION HAS PRODUCED A THICK AC CANOPY OVER NE TX/EXTREME
NW LA...ALTHOUGH IR IMAGERY DEPICTS WARMING CLOUD TOPS SUGGESTING
A WEAKENING TREND IS ONGOING ATTM. THIS MCV CENTER IS PROGGED TO
DRIFT NNE ACROSS NCNTRL TX TODAY...WHICH COULD MAINTAIN ELEVATED
CONVECTIVE DEBRIS OVER THE NRN HALF OF THE AREA THROUGH AT LEAST
THE FIRST HALF OF THE DAY...BEFORE POSSIBLY THINNING THIS
AFTERNOON. MY FORECAST MAX TEMPS MAY BE A BIT HIGH TODAY
ESPECIALLY IF THIS DEBRIS FIELD HANGS TOUGH TODAY...BUT HAVE
PLAYED THE PESSIMIST WITH IT THINNING LATER TODAY...ESPECIALLY AS
09Z TEMPS REMAIN IN THE MID/UPPER 70S. WHILE THE SHORT TERM PROGS
DO SUGGEST A WEAK SEABREEZE AFFECTING DEEP E TX/SRN SECTIONS OF
NCNTRL LA THIS AFTERNOON...ONLY THE LATEST HRRR RUN DEPICTS AT
LEAST ISOLATED CONVECTION DEVELOPING THIS AFTERNOON ALONG THE
RESIDUAL SHEAR AXIS...WHICH IS STILL WEAKLY REFLECTED IN THE OTHER
SHORT RANGE PROGS. IN ADDITION...THE 09Z SFC ANALYSIS INDICATES A
DISTINCT W-E GRADIENT IN SFC THETA-E FROM NEAR OSA TO ALONG THE
AR/LA LINE...INDICATIVE OF THE WEAK COLD POOL FROM CONVECTION THAT
AFFECTED THESE AREAS MONDAY AFTERNOON/EVENING. GIVEN THESE WEAK
SFC AND UPPER AIR FORCING MECHINISMS...AND THE FACT THAT THE CNTRL
TX MCV IS PROGGED TO LIFT NNE ACROSS THE STATE TODAY...HAVE
EXPANDED SLIGHT CHANCE POPS TO COVER MUCH OF THE REGION THIS
AFTERNOON...AND DID CARRY THEM THROUGH THE EVENING BEFORE THEY
DIMINISH WITH THE STABILIZING BNDRY LYR.
THE SHEAR AXIS IS EXPECTED TO WASH OUT OVERNIGHT WITH THE MCV
OPENING UP LATE...AS THE WRN ATLANTIC/CNTRL GULF OF MX UPPER RIDGE
EXPECTED TO BRIDGE NWD INTO THE LOWER MS VALLEY WEDNESDAY. STILL
SHOULD SEE A WEAK SEABREEZE AFFECTING THE SRN ZONES WEDNESDAY AND
THURSDAY AFTERNOONS/EARLY EVENINGS...BEFORE THE UPPER RIDGE CENTER
BECOMES ESTABLISHED OVER THE MID-SOUTH/LOWER MS VALLEY FRIDAY.
BOTH THE GFS AND ECMWF AMPLIFY THE RIDGE FARTHER N ACROSS THE SRN
PLAINS/MS VALLEY FRIDAY...AND KEEPS IT PERSISTENT THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. INCREASED SUBSIDENCE WILL RESULT IN
MAX TEMPS CLIMBS INTO THE UPPER 90S AREAWIDE...WITH EVEN SOME
TRIPLE DIGITS POSSIBLE OVER SOME AREAS THIS WEEKEND/EARLY NEXT
WEEK. THE MEDIUM RANGE PROGS DO BEGIN TO SLOWLY NUDGE THE RIDGE E
INTO THE SE STATES BY TUESDAY/WEDNESDAY...WITH WEAKNESSES RIDING W
BENEATH THE RIDGE ACROSS S LA/SRN MS AS EARLY AS MONDAY.
THUS...ISOLATED CONVECTION WILL BE POSSIBLE OVER NCNTRL LA MONDAY
AFTERNOON...BEFORE SPREADING FARTHER WNW TO ENCOMPASS MUCH OF THE
REGION BY THE END OF THE EXTENDED.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 95 75 96 76 97 / 10 10 10 10 10
MLU 95 73 96 74 97 / 20 20 10 10 10
DEQ 94 71 94 71 95 / 20 20 0 0 0
TXK 94 74 96 74 96 / 20 20 0 0 0
ELD 95 72 96 74 97 / 20 20 0 0 0
TYR 94 75 96 76 97 / 10 20 10 10 10
GGG 95 74 96 75 97 / 10 10 10 10 10
LFK 96 75 96 76 97 / 20 20 20 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
24
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
423 AM CDT TUE AUG 19 2014
.DISCUSSION...
THE MORNING WATER VAPOR IMAGERY INDICATES THAT THE MAIN SHORTWAVE
THAT PRODUCED EXTENSIVE CONVECTION JUST 24 HRS AGO OVER SW
AR/EXTREME NRN LA HAS SHIFTED E INTO NRN GA...WITH THE 00Z RAOB
500MB PLOT STILL REVEALING A WEAK SHEAR AXIS THAT EXTENDS FARTHER
W ACROSS NRN MS/N LA AND INTO NE TX. MEANWHILE...MOSAIC RADAR
IMAGERY ALSO INDICATES A WELL-DEFINED MCV SPINNING E OF
SJT...WHICH THE 00Z PROGS HAVE INITILIZED WELL ON AS CONVECTION
CONTINUES TO REGENERATE NEAR AND E OF THE CENTER OVER CNTRL TX.
THIS CONVECTION HAS PRODUCED A THICK AC CANOPY OVER NE TX/EXTREME
NW LA...ALTHOUGH IR IMAGERY DEPICTS WARMING CLOUD TOPS SUGGESTING
A WEAKENING TREND IS ONGOING ATTM. THIS MCV CENTER IS PROGGED TO
DRIFT NNE ACROSS NCNTRL TX TODAY...WHICH COULD MAINTAIN ELEVATED
CONVECTIVE DEBRIS OVER THE NRN HALF OF THE AREA THROUGH AT LEAST
THE FIRST HALF OF THE DAY...BEFORE POSSIBLY THINNING THIS
AFTERNOON. MY FORECAST MAX TEMPS MAY BE A BIT HIGH TODAY
ESPECIALLY IF THIS DEBRIS FIELD HANGS TOUGH TODAY...BUT HAVE
PLAYED THE PESSIMIST WITH IT THINNING LATER TODAY...ESPECIALLY AS
09Z TEMPS REMAIN IN THE MID/UPPER 70S. WHILE THE SHORT TERM PROGS
DO SUGGEST A WEAK SEABREEZE AFFECTING DEEP E TX/SRN SECTIONS OF
NCNTRL LA THIS AFTERNOON...ONLY THE LATEST HRRR RUN DEPICTS AT
LEAST ISOLATED CONVECTION DEVELOPING THIS AFTERNOON ALONG THE
RESIDUAL SHEAR AXIS...WHICH IS STILL WEAKLY REFLECTED IN THE OTHER
SHORT RANGE PROGS. IN ADDITION...THE 09Z SFC ANALYSIS INDICATES A
DISTINCT W-E GRADIENT IN SFC THETA-E FROM NEAR OSA TO ALONG THE
AR/LA LINE...INDICATIVE OF THE WEAK COLD POOL FROM CONVECTION THAT
AFFECTED THESE AREAS MONDAY AFTERNOON/EVENING. GIVEN THESE WEAK
SFC AND UPPER AIR FORCING MECHINISMS...AND THE FACT THAT THE CNTRL
TX MCV IS PROGGED TO LIFT NNE ACROSS THE STATE TODAY...HAVE
EXPANDED SLIGHT CHANCE POPS TO COVER MUCH OF THE REGION THIS
AFTERNOON...AND DID CARRY THEM THROUGH THE EVENING BEFORE THEY
DIMINISH WITH THE STABILIZING BNDRY LYR.
THE SHEAR AXIS IS EXPECTED TO WASH OUT OVERNIGHT WITH THE MCV
OPENING UP LATE...AS THE WRN ATLANTIC/CNTRL GULF OF MX UPPER RIDGE
EXPECTED TO BRIDGE NWD INTO THE LOWER MS VALLEY WEDNESDAY. STILL
SHOULD SEE A WEAK SEABREEZE AFFECTING THE SRN ZONES WEDNESDAY AND
THURSDAY AFTERNOONS/EARLY EVENINGS...BEFORE THE UPPER RIDGE CENTER
BECOMES ESTABLISHED OVER THE MID-SOUTH/LOWER MS VALLEY FRIDAY.
BOTH THE GFS AND ECMWF AMPLIFY THE RIDGE FARTHER N ACROSS THE SRN
PLAINS/MS VALLEY FRIDAY...AND KEEPS IT PERSISTENT THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. INCREASED SUBSIDENCE WILL RESULT IN
MAX TEMPS CLIMBS INTO THE UPPER 90S AREAWIDE...WITH EVEN SOME
TRIPLE DIGITS POSSIBLE OVER SOME AREAS THIS WEEKEND/EARLY NEXT
WEEK. THE MEDIUM RANGE PROGS DO BEGIN TO SLOWLY NUDGE THE RIDGE E
INTO THE SE STATES BY TUESDAY/WEDNESDAY...WITH WEAKNESSES RIDING W
BENEATH THE RIDGE ACROSS S LA/SRN MS AS EARLY AS MONDAY.
THUS...ISOLATED CONVECTION WILL BE POSSIBLE OVER NCNTRL LA MONDAY
AFTERNOON...BEFORE SPREADING FARTHER WNW TO ENCOMPASS MUCH OF THE
REGION BY THE END OF THE EXTENDED.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 95 75 96 76 97 / 10 10 5 5 5
MLU 95 73 96 74 97 / 20 20 5 5 5
DEQ 94 71 94 71 95 / 20 20 0 0 0
TXK 94 74 96 74 96 / 20 20 0 0 0
ELD 95 72 96 74 97 / 20 20 0 0 0
TYR 94 75 96 76 97 / 10 20 5 5 5
GGG 95 74 96 75 97 / 10 10 5 5 5
LFK 96 75 96 76 97 / 20 20 20 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
15
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
732 PM EDT WED AUG 20 2014
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 341 PM EDT WED AUG 20 2014
AN ACTIVE WARM FRONT WILL PUSH TOWARD SOUTHWEST LOWER MICHIGAN
THURSDAY AND THURSDAY NIGHT TRIGGERING SCATTERED SHOWERS AND
THUNDERSTORMS. THE STORMS ON THURSDAY NIGHT COULD PRODUCE HEAVY RAIN
AND A RISK OF FLOODING. A LOW THREAT FOR DAMAGING WINDS WILL ALSO
EXIST.
VERY WARM AND HUMID WEATHER CAN BE EXPECTED OVER THE WEEKEND INTO
EARLY NEXT WEEK WITH HIGHS POSSIBLY REACHING 90. A POP UP SHOWER OR
STORM WILL BE POSSIBLE EACH DAY BUT MOST OF THE TIME IT WILL BE DRY.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 341 PM EDT WED AUG 20 2014
THE MAIN FOCUS IS ON THE POTENTIAL FOR HEAVY RAIN/FLOODING AND
SEVERE WEATHER THURSDAY NIGHT AS AN ACTIVE WARM FRONT ACROSS IA/IL
SHIFTS NORTHEAST.
SEVERAL JET CORES/SPEED MAXIMA EMBEDDED WITHIN BUILDING UPPER RIDGE
OVER THE CENTRAL/NRN PLAINS WILL IMPACT THE AREA OVER THE NEXT 48
HOURS. DEPARTURE OF THE UPPER LOW CURRENTLY OVER ERN UPR MI ALLOWS
AN INFLUX OF WARM/UNSTABLE AIR FROM THE SOUTHWEST WITH EXTREMELY
HIGH PWAT AIR OF AROUND 2.2 INCHES.
THIS PATTERN VERY MUCH SUPPORTS THE CHANCE OF FLASH FLOODING WHERE
STORMS DEVELOP AND REPEAT IN A NORTHWEST TO SOUTHEAST FASHION. THE
ECMWF HAS BEEN QUITE CONSISTENT IN PLACING HIGHEST QPF THURSDAY
NIGHT OVER SW MI... AND AM HEAVILY FAVORING ITS SOLUTION AT THIS
TIME. STILL SOME UNCERTAINTY HOWEVER REGARDING LOW LEVEL JET
PLACEMENT/BEHAVIOR WHICH WILL DICTATE WHERE BEST QPF SETS UP.
GUIDANCE ALSO SUGGESTS THE POSSIBILITY OF ISOLATED SEVERE STORMS
WITH DAMAGING WINDS IN A NW TO SE CORRIDOR FROM ROUGHLY MINNEAPOLIS
TO MILWAUKEE/CHICAGO TO KALAMAZOO. 0-6KM DEEP LAYER SHEAR IS PROGGED
TO BE 35 TO 45 KTS WITH MU CAPES OF 1500-2500 J/KG. MCS ACTIVITY
TRACKING SE ALONG THIS CORRIDOR MAY CONTAIN BOWING LINE SEGMENTS
WHICH COULD PRODUCE AN EPISODE OR TWO OF SEVERE STORMS SOUTH OF I-96
THURSDAY NIGHT. ELEVATED NATURE OF THE CONVECTION HOWEVER COULD BE A
LIMITING FACTOR.
THURSDAY NIGHTS CONVECTION IS EXPECTED TO EXIT EARLY FRIDAY MORNING
LEAVING ONLY SCATTERED ACTIVITY AT BEST IN ITS WAKE. THE COOLING
EFFECTS OF THE NOCTURNAL CONVECTION WILL PROBABLY KEEP THE SFC WARM
FRONT SUPPRESSED SOUTH OF THE STATE FOR FRIDAY WITH SOME STRATUS
PERSISTING THROUGH AT LEAST EARLY AFTERNOON.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 341 PM EDT WED AUG 20 2014
THE LONG TERM PORTION OF THE FCST LOOKS RATHER WARM AND UNSETTLED
THROUGH THE PERIOD. PCPN CHCS WILL NOT BE HIGH MOST OF THE
PERIOD...HOWEVER SMALL CHCS WILL REMAIN PRESENT THROUGH MUCH OF THE
PERIOD WITH A COUPLE OF BETTER OPPORTUNITIES.
WARM FRONT IS EXPECTED TO BE SITUATED TO OUR SW AT THE BEGINNING OF
THE PERIOD ON SAT MORNING. THIS WARM FRONT WILL MAKE A GOOD PUSH
NORTH BY SUN AS THE UPPER RIDGE BUILDS OVER THE AREA IN RESPONSE TO
THE UPPER LOW TAKING SHAPE ACROSS THE ROCKIES. A CHC OF SHOWERS/
STORMS WILL EXIST AS THIS FRONT MOVES THROUGH. IT DOES LOOK LIKE THE
BEST CHC OF PCPN WITH THE FRONT WILL REMAIN WEST OF THE AREA WHERE
THE BEST LLJ IS FOCUSED.
ONCE THE FRONT MOVES THROUGH...WE CAN EXPECT TEMPS APPROACHING 90
THEN FOR THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK WITH H850
TEMPS AROUND 20C. HUMIDITY LEVELS WILL INCREASE ALSO. MODELS ARE
TRYING TO KICK OUT SOME LIGHT DIURNAL PCPN EACH DAY WITH THE GREAT
DEAL OF INSTABILITY THAT IS EXPECTED TO BE PRESENT. WE SHOULD BE
RATHER CAPPED SUN AND MON BASED ON FCST SOUNDINGS. CAN NOT RULE
SOMETHING POPPING UP ALONG A BOUNDARY SUCH AS A LAKE BREEZE OR SUCH.
A BETTER CHC OF SHOWERS/STORMS WILL COME LATE IN THE PERIOD. THE
ROCKIES LOW WILL GRADUALLY LIFT TO THE NE...AND FLATTEN THE UPPER
RIDGE IN THE PROCESS. THE LOWERING HEIGHTS/COOLING MID LEVELS WILL
COMBINE WITH A FRONT ALLOWED TO DROP DOWN TO BRING BETTER CHCS OF
RAIN.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 732 PM EDT WED AUG 20 2014
BESIDE THE FOG ISSUE TONIGHT ANOTHER FORECASTING ISSUE HAS
DEVELOPED... THAT IS THE RISK OF CONVECTION OVERNIGHT.
AS IT TURNS OUT THE ENTRANCE REGION OF THE POLAR JET SPEED MAX
CROSSES LOWER MICHIGAN AROUND 06Z. THAT LIFT INCREASES THE
MOISTURE IN THE 900 MB TO 700 MB LAYER WHICH IN TURN CREATES
ELEVATED INSTABILITY. THE GOOD NEWS IS THE AIR ABOVE 600 MB IS
VERY DRY YET SO ANY CELLS THAT WOULD TRY TO DEVELOP WOULD LIKELY
ENTRAIN TO MUCH DRY AIR. STILL THE POSSIBILITY EXISTS FOR A FEW
SHOWERS AND MAYBE EVEN A THUNDERSTORM IN THE 06Z-09Z TIME FRAME AT
MOST OF THE TAF SITES. ACTUALLY THE MORE WESTERN TAF SITES WOULD
BE HAVE A HIGHER RISK OF SEEING THE CONVECTION AS THE AXIS OF THE JET
CORE DOES NOT GET EAST OF LANSING. THE HRRR 20Z RUN DOES SHOW
CONVECTION DEVELOPING IN THAT TIME FRAME OVER SOUTHWEST LOWER
MICHIGAN. I PUT VCSH FOR THIS FOR NOW BUT WE WILL HAVE TO WATCH
TO SEE IF ANYTHING DEVELOPS.
OTHERWISE WITH LIGHT WINDS FOG MAY REDEVELOP OVERNIGHT HOWEVER IF
THE AFOREMENTIONED CONVECTION DEVELOPS THERE MAY BE ENOUGH CLOUDS
AROUND TO KEEP THE FOG FROM BECOMING DENSE.
THE WARM FRONT CONVECTION SHOULD BEING TO EFFECT OUR TAF SITES
AFTER 16Z SO I HAVE VCTS FOR THAT.
&&
.MARINE...
ISSUED AT 341 PM EDT WED AUG 20 2014
MAIN CONCERN IS AREAS OF DENSE FOG OVER THE NEXT SEVERAL DAYS AS
VERY WARM AND HUMID AIR MASS MOVES OVER THE COOLER LK WATERS. WINDS
AND WAVES ARE NOT EXPECTED TO EXCEED SMALL CRAFT CRITERIA AT THIS
TIME.
&&
.HYDROLOGY...
ISSUED AT 341 PM EDT WED AUG 20 2014
EXCESSIVE RAINFALL IS POSSIBLE THURSDAY NIGHT WITH PWATS OF 2.2
INCHES AND AN APPROACHING WARM FRONT UNDER A BUILDING UPPER RIDGE.
THIS PATTERN SUPPORTS THE POSSIBILITY OF FLOODING/FLASH FLOODING
ACROSS PARTS OF THE UPR MIDWEST/SRN GRTLKS REGION INCLUDING SW LWR
MI. DEPENDING ON HOW THE STORMS SET UP AND PERSIST... AREAL FLOODING
IS POSSIBLE THURSDAY NIGHT FOLLOWED BY THE POTENTIAL FOR RIVER
FLOODING IN THE DAYS FOLLOWING. SOME UNCERTAINTY STILL EXISTS
HOWEVER IN LOW LEVEL JET BEHAVIOR AND PLACEMENT OF BEST QPF.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...MEADE
MARINE...MEADE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
424 PM EDT TUE AUG 19 2014
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 422 PM EDT TUE AUG 19 2014
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW FROM WRN
LAKE SUPERIOR INTO W UPPER MI. A SHORTWAVE NEAR THE LOW CENTER
SUPPORTED AN AREA OF SHOWERS...SOME LOCALLY HEAVY...THROUGH CNTRL
UPPER MI. WITH THE SLOW FORWARD MOVEMENT...PWAT AROUND 1.5
INCHES...AND EFFICIENT WARM RAIN PROCESSES...NEARLY 2.0 INCHES OF
RAIN FELL AT THE NWS OFFICE BTWN 1915Z-1945Z. AN FLS WAS ISSUED TO
HIGHLIGHT THREAT FOR MINOR FLOODING WITH SMALL STREAMS AND LOW-LYING
AREAS. AT THE SFC...LOW PRES WAS LOCATED OVER NW UPPER MI.
EXPECT THE VERTICALLY STACKED LOW TO ONLY SLOWLY WOBBLE TO THE EAST
TO CNTRL/EAST UPPER MI BY 12Z/WED AND TO NEAR THE STRAITS BY 00Z/THU.
THERE WILL BE A CONTINUED THREAT FOR SOME LOCALLY HEAVY RAIN WITH
THE SHRTWV MOVING THROUGH CNTRL UPPER MI THIS EVENING.
ONLY ISOLD TSRA ARE EXPECTED...GIVEN AFTERNOON TRENDS AND MUCAPE BLO
1K J/KG.
OTHERWISE...HIGH RES MODELS AND UPSTREAM RADAR TRENDS SUGGEST RAIN
WILL BECOME MORE SCATTERED THIS EVENING AND DIMINISH FURTHER
OVERNIGHT. WITH ABUNDANT DEEP MOISTURE REMAINING OVER THE REGION
THROUGH WED MORNING...SOME SCT LIGHT SHOWERS OR DRIZZLE WILL REMAIN
POSSIBLE THROUGH THE MORNING...ESPECIALLY OVER THE N CNTRL AND EAST
EVEN WITH WEAK FORCING NEAR THE LOW. HOWEVER...ANY ADDITIONAL
RAINFALL AMOUNTS SHOULD BE LIGHT...LESS THAN A TENTH OF AN INCH.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 402 PM EDT TUE AUG 19 2014
THE UPPER LEVEL WAVE AND ASSOCIATED WEAK LOW PRESSURE SYSTEM THAT
ARE CURRENTLY OVER THE AREA WILL CONTINUE TO INFLUENCE THE UPPER
GREAT LAKES REGION INTO WEDNESDAY BEFORE PULLING OUT ON WEDNESDAY
NIGHT. AS THIS WAVE PULLS OUT...SHOULD SEE A DRY PERIOD OVER MUCH
OF THE U.P. FOR WEDNESDAY NIGHT INTO THURSDAY MORNING (ALTHOUGH
THERE COULD BE SOME LINGERING SHOWERS OVER THE NORTHEAST ON
WEDNESDAY EVENING) BEFORE THE NEXT WAVE ARRIVES THURSDAY AFTERNOON
AND REMAINS INTO FRIDAY. THE DRY PERIOD WILL BE AIDED BY THE WEAK
RIDGING ALOFT THAT WILL MOVE INTO THE UPPER GREAT LAKES REGION AND
ATTEMPT TO BUILD INTO THE GREAT LAKES REGION THROUGH THE WEEKEND.
AS THAT RIDGING OCCURS...AN UPPER TROUGH WILL ESTABLISH ITSELF
OVER THE NORTHERN ROCKIES AND EJECT OUT A COUPLE PIECES OF ENERGY
THROUGH THE REST OF THE EXTENDED PERIOD. THE FIRST WAVE WILL
MOVE INTO THE NORTHERN PLAINS ON WEDNESDAY AND THEN SHIFT NORTHEAST
ACROSS THE MINNESOTA ARROWHEAD THURSDAY EVENING AND INTO ONTARIO ON
FRIDAY. THERE ARE STILL SOME MODEL DIFFERENCES WITH HOW PROGRESSIVE
THIS SHORTWAVE AND ASSOCIATED WEAK LOW (AND WARM FRONT) ARE...AND IT
IS LARGELY TIED INTO THE STRENGTH OF THE SHORTWAVE. AT THIS
POINT...THE 12Z GFS APPEARS TO BE THE OUTLIER (KEEPS THE WARM FRONT
SOUTH OF THE CWA DUE TO WEAKER SHORTWAVE UNTIL THE NEXT WAVE
ARRIVES ON SATURDAY) WHILE THE 00Z ECMWF AND ITS ENSEMBLE
MEMBERS...ALONG WITH THE 12Z GEM/NAM...BRING THE WARM FRONT INTO THE
AREA LATE THURSDAY AFTERNOON AND PUSHING NORTHEAST OF THE AREA ON
FRIDAY NIGHT INTO SATURDAY. THINK THE NON GFS CONSENSUS IS THE WAY
TO GO AT THIS POINT AND FOLLOWS THE GENERAL IDEA FROM THE PREVIOUS
SHIFT. THEREFORE...WILL INCREASE PRECIP CHANCES FROM SOUTHWEST TO
NORTHEAST THURSDAY AFTERNOON INTO THURSDAY NIGHT AND THEN KEEP
CHANCE POPS INTO THE FIRST PART OF THE WEEKEND. WILL NEED TO KEEP
AN EYE ON CONVECTION FIRING IN EAST CENTRAL MINNESOTA AND NORTHWEST
WISCONSIN THURSDAY AFTERNOON ALONG THE WARM FRONT AND LOW LEVEL
MOISTURE TRANSPORT MAXIMUM IS LOCATED. COULD SEE SOME STRONG TO
POTENTIAL SEVERE STORMS IN THAT AREA...WHICH BASED OFF STORM MOTION
VECTORS WOULD TRY TO LIFT THEM EAST-NORTHEAST ALONG WITH THE FRONT
WHILE BUILDING TO THE SOUTHEAST. FAR WESTERN UPPER MICHIGAN WOULD
HAVE THE BEST OPPORTUNITY FOR SEEING THESE STRONGER STORMS HEADING
INTO THE EVENING HOURS.
ONCE THAT WAVE DECAYS AND SLIDES NORTHEAST OF THE
CWA...PRECIPITATION CHANCES WILL DEPEND ON OTHER WAVES EJECTING OUT
OF THE UPPER TROUGH OVER THE NORTHERN ROCKIES. RIDGE AXIS WILL BE
RIGHT OVER THE U.P. THROUGH SUNDAY AND THEN SHIFT EAST FOR THE
BEGINNING OF NEXT WEEK AS THE UPPER TROUGH GRADUALLY SHIFTS EAST.
WITH THAT RIDGE AXIS...IT APPEARS THAT SUNDAY WILL BE THE BEST
OPPORTUNITY FOR DRIER WEATHER BEFORE THE NEXT WAVE SLIDES NORTHEAST
OVER THE WESTERN HALF OF THE CWA SUNDAY NIGHT INTO MONDAY MORNING.
EXPECT IT TO BE FAIRLY MUGGY OVER THE AREA FRIDAY INTO THE
WEEKEND....ESPECIALLY WHEN COMPARED TO WHAT HAS BEEN SEEN IN THIS
REGION FOR MUCH OF THE SUMMER. AFTER THE NORMAL TO SLIGHTLY ABOVE
NORMAL TEMPERATURES VALUES THURSDAY THROUGH SUNDAY...THEY ARE
EXPECTED TO FALL BACK BELOW NORMAL FOR MONDAY AND TUESDAY BEHIND THE
COLD FRONT ASSOCIATED WITH THE WAVE THAT MOVES THROUGH ON SUNDAY
NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 203 PM EDT TUE AUG 19 2014
WITH A LOW PRESSURE SYSTEM REMAINING IN THE AREA WITH ABUNDANT LOW
LEVEL MOISTURE...LIFR TO VLIFR CONDITIONS SHOULD PREVAIL AT ALL
SITES THIS PERIOD WITH NRLY UPSLOPE FLOW AND OCCASIONAL LIGHT
SHOWERS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 PM EDT TUE AUG 19 2014
SOME FOG IS EXPECTED TO PERSIST OVER THE CNTRL AND ERN LAKE TONIGHT
GIVEN ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS. EXPECT WINDS
UNDER 20 KTS THROUGH SATURDAY AS A RELATIVELY WEAK PRESSURE GRADIENT
DOMINATES THE UPPER GREAT LAKES ABOVE THE RELATIVELY COLD WATERS OF
LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
122 AM EDT TUE AUG 19 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 322 PM EDT MON AUG 18 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A FAIRLY STRONG
SHRTWV OVER THE NRN PLAINS DRIFTING TO THE ESE INTO NW MN DOWNSTREAM
OF A RDG OVER WRN CANADA AND TOWARD A SHRTWV RDG STRETCHING FM
HUDSON BAY TOWARD THE SE GREAT LKS ON THE WRN FLANK OF A DEEP TROF
OVER THE CNDN MARITIMES. THERE IS ALSO A WEAKER SHRTWV MOVING E THRU
THE UPR LKS AHEAD OF THE MAIN DISTURBANCE APRCHG MN...AND THIS
FEATURE ALONG WITH ACCOMPANING AXIS OF GREATER H85 THETA E ADVCTN/A
FAIRLY MOIST 12Z GRB RAOB /KINX 36C AND PWAT 1.64 INCH OR ALMOST 175
PERCENT OF NORMAL/ HAS BEEN THE FOCUS FOR SOME SCT-NMRS SHOWERS
MAINLY OVER CENTRAL CWA TODAY. BUT QUITE A CONTRAST JUST TO THE E
WITH THE 12Z APX RAOB DISPLAYING A MUCH DRIER PROFILE...KINX -12C
AND PWAT 0.66 INCH OR ONLY 75 PERCENT OF NORMAL. THIS DRIER/STABLE
AIRMASS HAS SLOWED THE PROGRESS OF THE SHOWERS INTO THE AREA ARND
NEWBERRY SO FAR. THERE ARE MORE NMRS SHOWERS/A FEW TS MOVING INTO
WRN LK SUP CLOSER TO THE TRAILING SHRTWV. OTRW...QUITE A BIT OF CLD
COVER HAS LIMITED THE DIURNAL RISE OF TEMP AND DESTABILIZATION IN
THE ABSENCE OF STEEP LAPSE RATES SHOWN ON EVEN THE MOISTER 12Z GRB
RAOB...SO TS HAVE BEEN FEW AND FAR BTWN. BUT SOME HEAVY RAINS HAVE
FALLEN UNDER THE STRONGER SHOWERS WITH THE HIER PWAT/DEEPER MSTR.
MAIN FCST CONCERNS IN THE SHORT TERM ARE POPS RELATED TO THE TWO
DISTURBANCES THAT ARE MOVING THRU MN/THE UPR LKS.
LATE TODAY/TNGT...AS TROF OVER QUEBEC SLOWLY EXITS TO THE E...LEAD
SHRTWV MOVING THRU THE UPR LKS/ACCOMPANYING AXIS OF H85 THETA E
ADVCTN WL DRIFT TO THE E AND BRING SOME SHOWERS TO THE FAR ERN CWA
BY 00Z. ALTHOUGH THERE MAY BE ONLY SOME ISOLD/SCT SHOWERS OVER WRN
UPR MI WITH SOME H7-5 DRYING MOST OF TODAY...MORE NMRS SHOWERS/SOME
TS ASSOCIATED WITH THE STRONGER SHRTWV MOVING INTO MN WL ARRIVE OVER
THE FAR W ARND 00Z TOWARD AREA WHERE THE 12Z NAM/REGIONAL CNDN MODEL
SHOW HIER MUCAPE UP TO ABOUT 750 J/KG NEAR IWD. BUT SINCE THE MN
SHRTWV WL BE TENDING TO DIG ESEWD THRU THE NGT...THE 12Z NAM/
REGIONAL CNDN MODEL INDICATE THE MORE NMRS SHOWERS WL IMPACT WI
CLOSER TO MORE VIGOROUS H85-7 MSTR CNVGC/HIER MUCAPE IN THE 500-
1000J/KG THAT WL BE CONFINED TO WI. SO WL MAINTAIN THE HIEST LIKELY
POPS TOWARD THE WI BORDER... ALONG WITH THE TS CHANCES PER ABSENCE
OF FCST MUCAPE AOA 200 J/KG FARTHER N. BUT DEEP LYR QVECTOR CNVGC/
DEEP SATURATION ON FCST SDNGS ON THE CYC SIDE OF SHRTWV TRACK
JUSTIFIES AT LEAST 50-60 POPS OVER THE ENTIRE CWA EVEN IF THE BETTER
FORCING/INSTABILITY HOLD TO THE SW. EXPECT LTL DIURNAL TEMP DROP
WITH LOTS OF CLDS/LINGERING HIER PWAT IN THE 1.50-1.75 RANGE. ADDED
SOME PATCHY FOG...ESPECIALLY IN AREAS OVER THE CENTRAL THAT WL
EXPERIENCE UPSLOPE SE FLOW.
TUE...EXPECT CONTINUED SCT-NMRS SHOWERS AND A FEW TS AS THE SHRTWV/
SFC LO REFLECTION SLIDE ESEWD THRU NRN WI AND MAINTAINS DEEP MSTR...
CYC FLOW AND DEEP LYR QVECTOR CNVGC OVER UPR MI. FCST WL SHOW
DIMINISHING POPS IN THE AFTN OVER THE W WITH PASSAGE OF SHRTWV TO
THE E AND ARRIVAL OF SOME DNVA/DEEP LYR QVECTOR DVGC AFT 18Z. FOG IN
THE MRNG OVER MAINLY THE CENTRAL ZNS WL DSPT SLOWLY WITH DIURNAL
HEATING LIMITED BY EXTENSIVE CLD COVER.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 431 PM EDT MON AUG 18 2014
THE 500MB LOW CENTERED OVER UPPER MI AND LAKE SUPERIOR AT 00Z
WEDNESDAY WILL SHIFT ACROSS LAKE HURON WEDNESDAY NIGHT/THURSDAY
MORNING WITH A BRIEF RIDGE BUILDING ACROSS UPPER MI THURSDAY. THE
APEX OF THE RIDGE WILL SHIFT JUST TO OUR E THURSDAY NIGHT. A SIZABLE
TROUGH SET UP FROM FROM W AND CENTRAL CANADA THROUGH THE ENTIRE W
U.S. WEDNESDAY WILL SLOWLY SHIFT THE N CENTRAL U.S. FOR THE
WEEKEND...AND UPPER GREAT LAKES SUNDAY NIGHT/MONDAY.
AS FOR THE SFC FEATURES AND WX...THE EXITING SFC LOW OVER N LAKE MI
AT 00Z WEDNESDAY WILL LINGER THROUGH THE NIGHT BEFORE SHIFTING TO
LOWER MI THROUGH THE DAY WEDNESDAY. WITH WRAP AROUND/UPSLOPE
MOISTURE ACROSS THE AREA...EXPECT LIGHT SHOWERS TO LINGER THROUGH
MID DAY AT LEAST. THE BEST CHANCE OF THUNDERSTORMS WILL SINK SE WITH
THE SFC LOW.
IT LOOKS LIKE THE ONLY PERIOD OF MAINLY DRY WEATHER WILL BE LATE
WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING...DESPITE THE 500MB
RIDGE OVERHEAD THURSDAY THROUGH FRIDAY. THE LARGE HIGH PRESSURE OVER
QUEBEC...WITH A RIDGE EXTENDING OVER THE UPPER GREAT LAKES WILL EXIT
E ON FRIDAY. THERE STILL LOOKS TO BE PLENTY OF INCONSISTENCIES FOR
FRIDAY AFTERNOON ON. WILL CONTINUE TO RUN WITH A GENERAL CONSENSUS
FOR THIS PERIOD...WITH HAS AN ELONGATED SFC LOW FROM HUDSON BAY
THROUGH MN AND THE CENTRAL PLAINS AT 00Z SUNDAY. THE LOW WILL SLOWLY
SHIFT TO ONTARIO/FAR W LAKE SUPERIOR SATURDAY. THIS WOULD BRING WAA
TO THE AREA WITH HIGH TEMPS RETURNING TO NEAR NORMAL READINGS FRIDAY
AND SATURDAY. THE SFC TROUGH SHOULD BE OVER THE CWA SATURDAY
NIGHT/SUNDAY MORNING. HAVE SLOWLY DIMINISHING POPS FOR SUNDAY AND
MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 122 AM EDT TUE AUG 19 2014
ALTHOUGH THE SPECIFICS REMAIN UNCERTAIN...LIFR TO VLIFR CONDITIONS
SHOULD PREVAIL AT KCMX/KSAW THRU AT LEAST THE MORNING HRS UNDER
LIGHT UPSLOPE FLOW/DEEP MOISTURE AND SCT TO AT TIMES NMRS SHRA OVER
UPPER MI ASSOCIATED WITH DISTURBANCE MOVING SLOWLY ESEWD FROM MN. AT
KIWD...IFR CONDITIONS WILL FALL TO LIFR AND POTENTIALLY VLIFR AS
LIGHT UPSLOPE NORTHERLY WIND DEVELOPS LATER IN THE NIGHT. IFR
CONDITIONS SHOULD BE THE RULE THIS AFTN AT ALL TERMINALS...THOUGH
LOW MVFR CONDITIONS MAY OCCUR AT TIMES. ALL TERMINALS WILL FALL BACK
TO LIFR TONIGHT AS ABUNDANT MOISTURE LINGERS ON THE BACKSIDE OF
DISTURBANCE MOVING ACROSS THE UPPER LAKES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 322 PM EDT MON AUG 18 2014
ADDED SOME FOG TO THE FORECAST THRU MUCH OF TUE OVER MAINLY THE
CENTRAL LAKE GIVEN ARRIVAL OF DEEPER MOISTURE AND EXPECTED AREA OF
LOWER TEMPERATURES NEAR THE LINGERING COOLEST DEEPER WATER.
OTHERWISE... EXPECT WINDS UNDER 20 KTS OVER THE NEXT WEEK AS A
RELATIVELY WEAK PRESSURE GRADIENT DOMINATES THE UPPER GREAT LAKES
ABOVE THE CHILLY WATERS OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
1033 AM CDT TUE AUG 19 2014
.UPDATE...INCREASED POPS SLIGHTLY TO CARRY SLIGHT CHANCE
THUNDERSTORM WORDING ACROSS NW LOCATIONS THROUGH 1PM GIVEN CURRENT
RADAR TRENDS BUT ALSO CUT SOME FOR SW AREAS THROUGH THAT SAME TIME
PERIOD. HOURLY TEMP/DEWPOINTS WERE ALTERED SLIGHTLY BUT MAINLY ON
TRACK WITH LITTLE TO NO CHANGE IN EXPECTED HIGHS.
.DISCUSSION...A FEW THUNDERSTORMS ARE ONGOING IN AR/TN MOVING INTO
NORTH MS THIS HOUR. HI-RES MODELS ARE HAVING A HARD TIME RESOLVING
THIS ACTIVITY BUT THE RAP DOES INDICATE SOME LOWER CONDENSATION
PRESSURE DEFICITS IN CONJUNCTION WITH ISENTROPIC UPGLIDE AND
STEEPER LAPSE RATES IN THE VICINITY OF THE CURRENT ACTIVITY.
FOLLOWING THE RAP GUIDANCE, IT SUGGESTS A LOW-LVL CONVERGENCE AREA
TO PROPAGATE OUT OF THIS CLUSTER (LIKELY FROM AN OUTFLOW BOUNDARY)
THAT COULD ACT TO INITIATE NEW ACTIVITY THROUGH THE DAY AS
INSTABILITY BUILDS. MICROBURST RISK REVEALED SUBSTANTIAL SBCAPE
ABOVE 3000 J/KG BUT WITH PWATS UP NEAR 2" FEEL SCATTERED
SHOWERS/STORMS WILL BEGIN BY EARLY AFTN SOUTH OF THIS CLUSTER. SOME
STORMS COULD BECOME STRONG TO BRIEFLY SEVERE IF ORGANIZED ALONG A
COLD POOL BUT OVERALL COVERAGE OF THESE HAZARDS WILL BE ISOLATED.
WILL NOT INCLUDE ANY STRONG/SEVERE GRAPHIC UPDATES AT THIS TIME.
COVERAGE SHOULD DIMINISH THROUGH THE EVENING AS THE RIDGE
STRENGTHENS OVER THE REGION THROUGH THE NEXT SEVERAL DAYS.
AN UPDATED AVIATION DISCUSSION CAN BE FOUND BELOW. /ALLEN/
&&
.AVIATION...A MIX OF MVFR/VFR FLIGHT CATEGORIES ARE BEING OBSERVED
THIS MORNING AS LOW STRATUS HAS BEEN A LITTLE SLOWER TO ERODE THAN
PREVIOUSLY ANTICIPATED. STILL...VFR CONDITIONS ARE EXPECTED AS WE
MOVE INTO THE AFTERNOON HOURS WITH SCATTERED TO BROKEN CEILINGS
BETWEEN 3000-5000 FEET EXPECTED...ALONG WITH SOME MID AND HIGH
CLOUDS STREAMING OVERHEAD. SCATTERED CONVECTION IS AGAIN EXPECTED
THROUGH THE AFTERNOON TODAY. THIS COULD RESULT IN A BRIEF PERIOD OF
MVFR/IFR CEILINGS AND/OR VISIBILITIES IF CONVECTION IS OBSERVED
WITHIN A TAF SITES RESPECTED AERODROME. SHOWERS AND STORMS WILL
DISSIPATED THIS EVENING...WITH ANOTHER BOUT OF MVFR/IFR
CEILINGS/VISIBILITIES POSSIBLE EARLY WEDNESDAY MORNING DUE TO LOW
STRATUS AND/OR PATCHY FOG. WINDS TODAY WILL BE WEST SOUTHWESTERLY
BETWEEN 5-10 KNOTS...AND WILL GRADUALLY SUBSIDE TO LIGHT TO CALM
TONIGHT. /19/
&&
.PREV DISCUSSION... /ISSUED 403 AM CDT TUE AUG 19 2014/
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...AS RIDGING CONTINUES
OVER THE CENTER OF THE COUNTRY...THE ARKLAMISS REGION REMAINS UNDER
NORTHWEST FLOW ALOFT. A TROUGH AXIS IS LOCATED ACROSS EASTERN
MISSISSIPPI AND ALABAMA THIS MORNING AND WILL CONTINUE THERE TODAY.
THIS SHOULD COMBINE WITH ENOUGH MOISTURE TO BRING SOME ADDITIONAL
SHOWERS AND STORMS TODAY. WHILE SOME STORMS WILL BE POSSIBLE ACROSS
WESTERN ZONES...HEIGHTS WILL BE RISING IN THIS REGION AND SHOULD
WORK TO SUPPRESS CONVECTION A BIT MORE THERE. WHILE CONVECTION IN
THIS NORTHWEST FLOW REGIME HAS NOT BEEN DEPICTED TERRIBLY WELL ON
MODELS OF LATE...HI-RES MODELS AND EVEN THE LOCAL WRF SEEM TO
INDICATE THE BEST CHANCES OF RAIN TODAY WILL BE IN THE EAST AND HAVE
LEANED MORE TOWARD THE ECMWF WITH HIGHER RAIN CHANCES IN THIS
REGION. HIGHS TODAY ARE EXPECTED TO BE IN THE LOWER 90S BUT WITH
HUMIDITY...HEAT INDICES WILL NEAR 100 DEGREES.
THROUGH WEDNESDAY NIGHT...THE UPPER TROUGH WILL CONTINUE TO PUSH OFF
TO THE EAST AND UPPER RIDGING WILL MOVE INTO THE REGION FOR A WHILE.
THERE COULD BE SOME SMALL RAIN CHANCES IN THE FAR SOUTH ON WEDNESDAY
BUT IT APPEARS THAT MOST OF THE ARKLAMISS SHOULD BE DRY AS HEIGHTS
WILL CONTINUE TO BUILD. TEMPERATURES ON WEDNESDAY WILL BE A TAD
WARMER AND COULD FLIRT WITH THE 95-97 DEGREE RANGE. WEDNESDAY WILL
BE A BIT MORE MUGGY AS THE COMBINATION OF HEAT AND 70 DEGREE
DEWPOINTS WILL BRING HEAT INDICES NEAR 105 DEGREES. WILL CONTINUE
WITH THE LIMITED RISK CURRENTLY ADVERTISED IN THE HWO AND GRAPHICS
FOR HEAT INDICES DURING THIS TIME PERIOD. OVERNIGHT LOWS WILL DROP
LOW ENOUGH TO PRECLUDE ANY NEED FOR AN ADVISORY. /28/
LONG TERM...THURSDAY THROUGH MONDAY...HOTTER AND DRIER THROUGH THE
PERIOD. THURSDAY MORNING A LARGE 593DAM HIGH ATOP A 1019MB SURFACE
HIGH WILL BE CENTERED JUST SOUTHEAST OF OUR CWA. THE SURFACE HIGH
WILL BECOME CENTERED JUST SOUTH OF OUR CWA WHILE THE LARGE MID LEVEL
HIGH STRENGTHENS AND BECOMES CENTERED OVER OUR CWA BY THURSDAY
EVENING. A RATHER MOIST AIRMASS WILL BE IN PLACE WITH PWS OF 1.7-1.8
INCHES AND SURFACE DEW POINTS IN THE LOWER 70S. THE NORMAL AFTERNOON
HIGHS ARE AROUND 92F AND TEMPERATURES WILL TOP OUT THURSDAY ABOVE
NORMAL AT 95-97F AT MOST SITES. MODEL SOUNDINGS SUGGEST DRIER AIR
WILL MIX DOWN DURING THE AFTERNOON LOWERING DEW POINTS IN THE UPPER
60S. THIS WILL KNOCK THE HUMIDITY DOWN SOME BUT THE HEAT AND
HUMIDITY WILL COMBINE FOR MAXIMUM HEAT INDEX VALUES OF 100-103
THURSDAY. ISOLATED AFTERNOON STORMS WILL BE POSSIBLE IN THE
SOUTHWEST THURSDAY BUT RAIN CHANCES WILL REMAIN VERY LOW ELSEWHERE
THROUGH THE END OF THE WEEK. MODEL CONSENSUS IS A LITTLE SLOWER IN
BREAKING DOWN THE LARGE RIDGE OVER OUR AREA UNTIL IT BEGINS SHIFTING
EAST MONDAY. AS A RESULT HEAT AND HUMIDITY WILL REMAIN A CONCERN
THROUGH THE WEEKEND INTO MONDAY. ABOVE NORMAL TEMPERATURES TOPPING
OUT IN THE UPPER 90S EACH DAY WILL COMBINE WITH HIGH HUMIDITY TO
RESULT IN HEAT INDEX VALUES PEAKING AROUND 105 FOR SEVERAL HOURS
EACH AFTERNOON. A HEAT ADVISORY MAY BE NEEDED BY THE END OF THE WEEK
IF GREATER HUMIDITY CAN BE MAINTAINED INTO THE AFTERNOON HOURS. AS
THE MID LEVEL RIDGE SHIFTS EAST MONDAY OUR SOUTHERN ZONES WILL SEE A
SLIGHT CHANCE OF STORMS BY AFTERNOON AND EVENING DUE ALSO IN PART TO
THE SEA BREEZE FRONT PUSHING INTO THE AREA. /22/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 94 73 96 73 / 36 14 7 6
MERIDIAN 92 71 96 72 / 42 12 10 5
VICKSBURG 94 71 96 71 / 20 11 4 7
HATTIESBURG 95 74 97 74 / 44 14 25 9
NATCHEZ 93 73 94 73 / 25 11 14 10
GREENVILLE 94 74 96 74 / 21 9 3 6
GREENWOOD 94 73 97 73 / 29 10 4 5
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
ALLEN/19/28/22
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
625 PM CDT WED AUG 20 2014
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 354 PM CDT WED AUG 20 2014
RATHER DIFFICULT FORECAST TONIGHT. THERE HAVE BEEN LOTS OF MID LEVEL
CLOUDS HANGING ACROSS THE AREA THIS AFTERNOON...AND HAVE KEPT
TEMPERATURES DOWN A BIT. CLOUDS HAVE BEGUN TO CLEAR SLOWLY...AND ARE
NOW ALLOWING FOR SOME HEATING AND INCREASING INSTABILITY. DO NOT
HAVE A GOOD FEEL IN TERMS OF CONVECTION TONIGHT...AS MODELS HAVE
BEEN INCONSISTENT AND PRIMARY FORCING REMAINS MOSTLY NORTH OF THE
AREA. FOR THESE REASONS...WILL LOWER POPS A BIT. AS
MENTIONED...INSTABILITY IS INCREASING WITH LITTLE SURFACE BASED CIN
REMAINING ACROSS THE AREA. AN ELONGATED AREA OF LOW PRESSURE EXTENDS
FROM WESTERN SD TO WESTERN KS...AND COULD BE THE FOCUS FOR ISOLATED
STORM DEVELOPMENT THOUGH THE EVENING. A WARM FRONT ALSO EXTENDS FROM
WEST TO EAST ACROSS NORTHERN NEBRASKA...AND COULD ALSO SERVE AS A
FOCUS FOR STORM DEVELOPMENT. YET ANOTHER AREA TO WATCH WILL BE
ACROSS NORTHEAST COLORADO THIS EVENING...AS HRRR MODEL CONTINUES TO
INDICATE STORMS MOVING NORTHEAST INTO SOUTHWEST NEBRASKA THIS
EVENING. SO LOTS OF AREAS TO WATCH...BUT LOW CONFIDENCE ON ANY ONE
SCENARIO MATERIALIZING. WILL CONTINUE TO MONITOR.
WEAK COOL FRONT WILL SETTLE JUST SOUTHEAST OF THE AREA THURSDAY.
OVERALL SHOULD BE A FAIRLY QUITE WEATHER DAY...WITH LIGHT NORTH
WINDS AND TEMPERATURES IN THE UPPER 80S AND LOWER 90S.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT WED AUG 20 2014
MAIN FOCUS WILL BE THE STORM SYSTEM MOVING IN THIS WEEKEND WITH
THUNDERSTORM CHANCES THURSDAY THROUGH SUNDAY.
LOWERED PRECIPITATION CHANCES ACROSS THE SOUTHERN PART OF THE
FORECAST AREA AS THE LATEST MODELS ARE TRENDING DRIER DUE TO LACK
OF MOISTURE. KEPT THE POPS ACROSS THE NORTHWEST AS MODELS SEEM TO
FAVOR STRONGER FORCING AND BETTER MOISTURE AS AN UPPER LEVEL SHORT
WAVE TROF PUSHES ACROSS THE AREA. HELD OFF HIGHER PRECIPITATION
CHANCES ACROSS THE SOUTHWEST UNTIL FRIDAY AFTERNOON AND EVENING AS
CONFIDENCE IS GREATER IN THUNDERSTORM DEVELOPMENT AFTER 18Z. SYSTEM
CURRENTLY ACROSS THE SOUTHWESTERN U.S. WILL CONTINUE TO ADVECT
NORTHEASTWARD AND WILL COMBINE WITH THE NORTHERN SYSTEM CURRENTLY
ACROSS THE GULF OF ALASKA. THE SOUTHWEST SYSTEM WILL TRANSPORT
MOISTURE AND VORTICITY ACROSS THE FORECAST AREA FRIDAY AFTERNOON.
BY 00Z SATURDAY PRECIPITABLE WATER INCREASES TO 150 PERCENT.
SATURDAY NIGHT INTO SUNDAY...AN UPPER LEVEL SHORT WAVE TROF WILL
PUSH ACROSS THE FORECAST AREA PUSHING THE RIDGE EASTWARD BRINGING
COLDER TEMPERATURES WITH IT. HIGHS ON SUNDAY WILL BE AROUND 10
DEGREES COOLER THAN SATURDAY. COOLER TEMPERATURES WILL CONTINUE
THROUGH WED WHEN NEXT TROF IS SET TO PUSH THROUGH THE AREA. THIS
SYSTEM WILL BRING STRONG LIFT AS MODELS SUGGEST AN INCREASE IN OMEGA
VALUES AND AN ABUNDANT AMOUNT OF MOISTURE WITH DEWPOINTS IN THE 60S
CREATING A FAVORABLE THUNDERSTORM DEVELOPMENT TO BE IN PLACE THE
NEXT SEVERAL DAYS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 623 PM CDT WED AUG 20 2014
VFR IS GENERALLY EXPECTED TONIGHT AND THURSDAY.
ISOLATED TSTMS NEAR KSNY-KOGA ARE EXPECTED TO DISSIPATE AROUND 03Z
OR SOONER WITH THE LOSS OF HEATING. THE TSTM ACTIVITY FROM KBBW-KGLD IS
EXPECTED TO CONTINUE THIS EVENING...PERHAPS LASTING UNTIL 06Z OR
LATER BUT REMAIN ISOLATED. THE STORMS SHOULD TRACK NORTHEAST ALONG
A KGLD-KBBW-KONL LINE MAINLY AFFECTING AREAS EAST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...TAYLOR
LONG TERM...GOMEZ
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
624 PM CDT WED AUG 20 2014
.SHORT TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 334 PM CDT WED AUG 20 2014
UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE OVER THE NEXT WEEK
WITH SEVERAL OPPORTUNITIES FOR THUNDERSTORMS. TIMING THESE CHANCES
ALONG WITH INCREASE IN HEAT AND HUMIDITY ARE THE PRIMARY FORECAST
CONCERNS.
MORNING UPPER AIR CHARTS SHOWED MID LEVEL TROUGH EXTENDING FROM THE
CANADIAN ROCKIES INTO SOUTHERN CALIFORNIA...WITH SOUTHWEST FLOW
AHEAD OF THE TROUGH RIDING INTO THE NORTHERN PLAINS. UPPER RIDGE
AXIS WAS CURRENTLY OVER THE MISSOURI RIVER VALLEY...BUT IS FORECAST
TO SHIFT EAST AND FLATTEN A BIT ON THURSDAY. THIS WILL LEAVE OUR
AREA UNDER SOUTHWEST FLOW ALOFT...WITH PATH FOR EJECTING SHORTWAVES
OVER NEBRASKA AND THE DAKOTAS. ALSO OF NOTE WAS PLUME OF MID LEVEL
MOISTURE EXTENDING FROM THE SOUTHERN BAJA INTO WESTERN KANSAS AND
SOUTHWEST NEBRASKA. WITH ONLY A SLOW DRIFT TO WESTERN
TROUGH...EXPECT THIS MOISTURE PLUME TO EXPAND OVER EASTERN NEBRASKA
AND WESTERN IOWA AND REMAIN IN PLACE AT LEAST INTO THE WEEKEND.
USING 700MB DEW POINT TEMPERATURES AS A PROXY...MODELS CONCUR WITH
THIS EXPECTATION. THE RESULT OF THESE PARAMETERS WILL BE AN
ATMOSPHERE PRIMED FOR SCATTERED CONVECTION AS SHORTWAVES ROLL INTO
THE PLAINS.
TIMING OF THOSE SHORTWAVES WILL PROVE DIFFICULT MORE THAN A DAY TO
TWO OUT. HOWEVER MODELS AGREE ON A SIGNIFICANT SHORTWAVE MOVING INTO
THE PLAINS FRIDAY NIGHT...OUR MOST LIKELY TIME FOR WIDESPREAD HEAVY
RAINS.
FOR TONIGHT...WATER VAPOR LOOPS IMPLY A SHORTWAVE IN WESTERN KANSAS
THIS AFTERNOON...EXPECTED TO LIFT NORTHEAST ACROSS OUR CWA LATER
THIS EVENING AND OVERNIGHT. GREATER THAN 7 C/KM MID LEVEL LAPSE
RATES WILL BE IN PLACE ALONG WITH ABUNDANT MID LEVEL MOISTURE.
EXPECT SCATTERED THUNDERSTORMS TO FIRE AFTER MIDNIGHT WHEN LOW LEVEL
JET KICKS UP TO 35KT WITH APPROACH OF SHORTWAVE. MAIN AREA OF
CONCERN WILL BE OVER OUR NORTHERN CWA THEN. HOWEVER THIS
EVENING...CONVECTION FROM EARLIER THIS MORNING MOVING ACROSS IOWA
LAID DOWN AN OUTFLOW BOUNDARY WHICH MOVED INTO SOUTHWEST IOWA AND
NORTHERN MISSOURI. VISIBLE SATELLITE PICS SHOW A LINE OF CUMULUS
ALONG THIS BOUNDARY...AND RAP MODEL SUGGESTS MLCAPE IS APPROACHING
3500 J/KG IN NORTHWEST MISSOURI ALONG WITH DIMINISHING CAP. LATEST
RAP AND HRRR FORECASTS KEEP CONVECTION IN CHECK THERE...BUT HAVE
ADDED SMALL POPS FOR SEVERAL HOURS THIS EVENING.
OVERNIGHT CONVECTION SHOULD BE EXITING THE CWA OR DIMINISHING BY MID
MORNING. EXPECT CLOUDS TO CLEAR ALLOWING FOR PLENTY OF INSOLATION IN
THE AFTERNOON WITH TEMPERATURES WELL INTO THE 90S AND DEW POINTS
CLOSE TO 70. A WEAK FRONTAL BOUNDARY IS FORECAST TO SETTLE INTO
NORTHEAST NEBRASKA THURSDAY AFTERNOON BEHIND WEDNESDAY NIGHT
SHORTWAVE...AND COULD FOCUS THUNDERSTORM CHANCES THERE. RELATIVELY
WARM TEMPERATURES ALOFT WILL LIKELY SUPPRESS CONVECTION IN THE
AFTERNOON...WITH BETTER CHANCES COMING LATER IN THE EVENING AS THE
FRONT SETTLES SOUTH INTO SOUTHEAST NEBRASKA AND SOUTHWEST IOWA AND
MID LEVEL TEMPERATURES COOL A BIT. CONTINUED ISENTROPIC UPGLIDE OVER
FRONTAL BOUNDARY IN MOIST ATMOSPHERE SUGGESTS AT LEAST SCATTERED
CONVECTION IS POSSIBLE THROUGH THE NIGHT.
MOST OF DAY FRIDAY SHOULD BE DRY AFTER MORNING STORMS IN THE SOUTH
MOVE OFF TO THE EAST. FRONTAL BOUNDARY WILL BEGIN LIFTING TO THE
NORTH DURING THE DAY WITH APPROACH OF STRONG SHORTWAVE FRIDAY NIGHT.
INSTABILITY FORECASTS SHOW 2000-3000 J/KG OF SURFACE-BASED CAPE
FRIDAY AFTERNOON...BUT SOUNDINGS SUGGEST A MODEST CAP WILL HOLD OFF
STORMS UNTIL NEAR 00Z OR PROBABLY AFTER. CHANCES INCREASE MARKEDLY
FRIDAY NIGHT AS SHORTWAVE AND SURFACE LOW MOVE NORTHEAST THROUGH THE
CWA. CURRENT TRACK PLACES NORTHEAST NEBRASKA IN THE CORRIDOR OF
HEAVIEST POTENTIAL RAINFALL WHERE PRECIPITABLE WATER WILL LIKELY
EXCEED 2 INCHES. CURRENT HPC QPF PROGS PAINT ABOUT THREE-QUARTERS OF
AN INCH OF RAIN IN NORTHEAST NEBRASKA...BUT WILL LIKELY SEE MUCH
MORE THAN THAT IN LOCAL AREAS GIVEN MOISTURE AVAILABLE AND POTENTIAL
FOR TRAINING OF STORMS. EXPECT ACTIVITY TO BE EXITING TO OUR
NORTHEAST SATURDAY MORNING...BUT LEFTOVER BAROCLINIC ZONE AND WIND
SHIFT WILL REMAIN IN PLACE FOR THE POTENTIAL FOR MORE STORMS LATER
IN THE DAY SATURDAY. WILL MAINTAIN A SMALL CHANCE FOR ADDITIONAL
AFTERNOON STORMS...EXPECTING SUBSIDENCE BEHIND EXITING SHORTWAVE TO
SUPPRESS CONVECTION MOST OF THE AFTERNOON.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 334 PM CDT WED AUG 20 2014
CONTINUED CHANCES OF THUNDERSTORMS WILL REMAIN JUST ABOUT EACH
PERIOD IN THE LONGER TERM FORECAST THROUGH WEDNESDAY. WESTERN UPPER
TROUGH WILL SLOWLY DRIFT FROM THE ROCKIES SATURDAY NIGHT INTO THE
PLAINS BY WEDNESDAY. ECMWF IS A LITTLE MORE PROGRESSIVE THAN THE GFS
WITH THIS MOVEMENT...BUT EVEN THE ECMWF LEAVES SOME SEMBLANCE OF A
TROUGH/LOW IN THE PLAINS THEN.
USING A BLEND OF ECMWF AND GFS...AND WHERE SOME CONSISTENCY IS
SHOWN...BEST CHANCES FOR MORE WIDESPREAD CONVECTION IS EXPECTED
MONDAY NIGHT INTO TUESDAY...THEN AGAIN TUESDAY NIGHT INTO WEDNESDAY.
BEFORE THEN...IMPULSES RIDING THROUGH MID LEVEL FLOW COULD SPARK
AREAS OF STORMS AT JUST ABOUT ANY TIME AS FRONTAL BOUNDARY MEANDERS
NORTH AND SOUTH THROUGH THE CWA AHEAD OF AND BEHIND EACH WAVE.
TEMPERATURES SHOULD MODERATE SOME THROUGH THE PERIOD...BEGINNING
WITH SUNDAY IN THE 80S TO NEAR 90...THEN RANGING FROM THE UPPER 70S
TO MIDDLE 80S MONDAY THROUGH WEDNESDAY.
&&
.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 619 PM CDT WED AUG 20 2014
VFR CONDITIONS ARE EXPECTED AT THE TAFS SITES THROUGH MUCH OF THE
PERIOD. A FEW SPOTTY THUNDERSTORMS ARE POSSIBLE IN AND AROUND THE
TAF SITES...BUT CONFIDENCE IS TOO LOW TO INCLUDE THEM IN THE TAF
AT THIS POINT.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...KERN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
521 PM CDT TUE AUG 19 2014
.UPDATE...
ISSUED AT 521 PM CDT TUE AUG 19 2014
UPDATED TO INCLUDE A SLIGHT CHANCE FOR THUNDERSTORMS FROM SWRN
NEBR INTO CENTRAL NEBRASKA AS THIS EVENING PROGRESSES. LATEST
REGIONAL RADAR MOSAIC SHOWS SCATTERED THUNDERSTORMS FROM NEAR
SCOTTSBLUFF THROUGH FORT MORGAN AND LAST CHANCE COLORADO. THE
LATEST HRRR AND RAP13 INDICATE THIS TO PUSH NORTHEAST AND INCREASE
IN COVERAGE INTO WRN NEBR THIS EVENING. RECENT ISOLATED
DEVELOPMENT NOW IN SHERIDAN AND CHERRY COUNTY ATTM.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 337 PM CDT TUE AUG 19 2014
SHORTWAVE RIDGING ALOFT CURRENTLY RESIDES OVER THE AREA...WITH VERY
LITTLE IN THE WAY OF CLOUD COVER EXCEPT FOR SOME HIGH CIRRUS CLOUDS.
SHORT TERM HRRR MODEL SUGGESTS THUNDERSTORMS WILL DEVELOP OVER THE
HIGHER TERRAIN TO THE WEST LATE THIS AFTERNOON...AND THEN DRIFT EAST
INTO WESTERN NEBRASKA THIS EVENING. LATEST VISIBLE SATELLITE TRENDS
CONFIRMS THIS THINKING...WITH QUITE A BIT IN THE WAY OF TOWERING
CUMULUS FROM CHEYENNE DOWN THROUGH THE DENVER METRO. SOUTHERLY LOW
LEVEL JET WILL INCREASE TO AROUND 35 KTS THIS EVENING...WHICH MAY
HELP SUPPORT STORMS AS THEY TRACK EAST. NOT EXPECTING COVERAGE TO BE
WIDESPREAD...AND DUE TO THE RIDGING ALOFT...NOT REAL CONFIDENT ON
HOW FAR EAST STORMS WILL MAKE IT. LATER TONIGHT...DECENT MID LEVEL
INSTABILITY DEVELOPS ACROSS NORTH CENTRAL INTO NORTHEAST
NEBRASKA...AND EXPECT AT LEAST SCATTERED COVERAGE OF ELEVATED
THUNDERSTORMS TO DEVELOP WITHIN AREA OF ISENTROPIC ASCENT.
A SURFACE TROUGH WILL EXTEND FROM NORTHEAST TO SOUTHWEST WEDNESDAY
AFTERNOON...AND SHOULD BE THE FOCUS FOR SCATTERED LATE AFTERNOON
THUNDERSTORMS. THE NAM MODEL IS THE FARTHEST EAST WITH THE
TROUGH...WHILE THE NMM...ARW AND GEM REGIONAL HOLD THE TROUGH BACK
FROM ROUGHLY AINSWORTH TO IMPERIAL. DECENT INSTABILITY DEVELOPS BY
AFTERNOON ALONG AND EAST OF THE TROUGH...WITH SURFACE BASED CAPES
APPROACHING 4000 J/KG. A BELT OF STRONGER MID LEVEL WINDS WILL ALSO
BE PRESENT BY AFTERNOON ON THE SOUTHERN FLANK OF A SHORTWAVE
CROSSING THE NORTHERN PLAINS. THE SYNOPTIC SET UP APPEARS SIMILAR TO
THE SUNDAY SEVERE EVENT...AND AGREE WITH THE STORM PREDICTION CENTER
SLIGHT RISK FOR SEVERE STORMS EAST OF HIGHWAY 83.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 337 PM CDT TUE AUG 19 2014
THE WEAK FRONT WILL CROSS CENTRAL NEBRASKA WEDNESDAY NIGHT AND
GENERATE A BAND OF THUNDERSTORMS...ESPECIALLY IN CENTRAL AND NORTH
CENTRAL NEBRASKA. MODEL OUTPUT STATISTICS INDICATE PROBABILITY/
COVERAGE OF 20-30 PERCENT IN THE SANDHILLS AND 30-40 PERCENT IN
CENTRAL AND NORTH CENTRAL NEBRASKA. THAT SEEMS REASONABLE. SURFACE
BASED CAPE IN CENTRAL AND NORTH CENTRAL NEBRASKA IS PRETTY HIGH AT
3500-4000J/KG WITH BULK SHEAR (0-6KM) AROUND 30KT. WITH STORM MOTION
240-260 AT 15-25KT...STORM RELATIVE HELICITY IS EXPECTED TO BE
110-200. SEVERE STORMS ARE POSSIBLE INTO THE EVENING...THOUGH WE
WILL NOT INCLUDE THE MENTION IN THE FORECAST FOR WEDNESDAY NIGHT.
A BOUNDARY LIFTING NORTH INTO SOUTHERN NEBRASKA WILL BRING THE
POSSIBILITY OF THUNDERSTORMS TO SOUTH CENTRAL AND SOUTHWEST NEBRASKA
THURSDAY NIGHT. AS THE BOUNDARY MAKES ITS WAY A LITTLE FARTHER NORTH
FRIDAY...THERE IS A POSSIBILITY OF THUNDERSTORMS IN CENTRAL AND
NORTHERN NEBRASKA.
FINALLY...SATURDAY NIGHT AND SUNDAY...A COOL FRONT COMES ACROSS
NEBRASKA AND THE PATTERN IS NOT AS FAVORABLE FOR STRONG CONVECTION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1239 PM CDT TUE AUG 19 2014
VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA THROUGH TONIGHT. ISOLATED THUNDERSTORMS MAY MOVE EASTWARD
INTO FAR WESTERN NEBRASKA THIS EVENING...AND SOME ISOLATED
DEVELOPMENT IS ALSO POSSIBLE LATE TONIGHT ACROSS NORTH CENTRAL
NEBRASKA. DUE TO THE ISOLATED NATURE...NO MENTION IS WARRANTED IN
THE OFFICIAL TAF FORECAST. WINDS WILL GENERALLY BE SOUTHEAST
AROUND 10 KTS THROUGH TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ROBERG
SHORT TERM...TAYLOR
LONG TERM...SPRINGER
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
338 PM CDT TUE AUG 19 2014
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 337 PM CDT TUE AUG 19 2014
SHORTWAVE RIDGING ALOFT CURRENTLY RESIDES OVER THE AREA...WITH VERY
LITTLE IN THE WAY OF CLOUD COVER EXCEPT FOR SOME HIGH CIRRUS CLOUDS.
SHORT TERM HRRR MODEL SUGGESTS THUNDERSTORMS WILL DEVELOP OVER THE
HIGHER TERRAIN TO THE WEST LATE THIS AFTERNOON...AND THEN DRIFT EAST
INTO WESTERN NEBRASKA THIS EVENING. LATEST VISIBLE SATELLITE TRENDS
CONFIRMS THIS THINKING...WITH QUITE A BIT IN THE WAY OF TOWERING
CUMULUS FROM CHEYENNE DOWN THROUGH THE DENVER METRO. SOUTHERLY LOW
LEVEL JET WILL INCREASE TO AROUND 35 KTS THIS EVENING...WHICH MAY
HELP SUPPORT STORMS AS THEY TRACK EAST. NOT EXPECTING COVERAGE TO BE
WIDESPREAD...AND DUE TO THE RIDGING ALOFT...NOT REAL CONFIDENT ON
HOW FAR EAST STORMS WILL MAKE IT. LATER TONIGHT...DECENT MID LEVEL
INSTABILITY DEVELOPS ACROSS NORTH CENTRAL INTO NORTHEAST
NEBRASKA...AND EXPECT AT LEAST SCATTERED COVERAGE OF ELEVATED
THUNDERSTORMS TO DEVELOP WITHIN AREA OF ISENTROPIC ASCENT.
A SURFACE TROUGH WILL EXTEND FROM NORTHEAST TO SOUTHWEST WEDNESDAY
AFTERNOON...AND SHOULD BE THE FOCUS FOR SCATTERED LATE AFTERNOON
THUNDERSTORMS. THE NAM MODEL IS THE FARTHEST EAST WITH THE
TROUGH...WHILE THE NMM...ARW AND GEM REGIONAL HOLD THE TROUGH BACK
FROM ROUGHLY AINSWORTH TO IMPERIAL. DECENT INSTABILITY DEVELOPS BY
AFTERNOON ALONG AND EAST OF THE TROUGH...WITH SURFACE BASED CAPES
APPROACHING 4000 J/KG. A BELT OF STRONGER MID LEVEL WINDS WILL ALSO
BE PRESENT BY AFTERNOON ON THE SOUTHERN FLANK OF A SHORTWAVE
CROSSING THE NORTHERN PLAINS. THE SYNOPTIC SET UP APPEARS SIMILAR TO
THE SUNDAY SEVERE EVENT...AND AGREE WITH THE STORM PREDICTION CENTER
SLIGHT RISK FOR SEVERE STORMS EAST OF HIGHWAY 83.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 337 PM CDT TUE AUG 19 2014
THE WEAK FRONT WILL CROSS CENTRAL NEBRASKA WEDNESDAY NIGHT AND
GENERATE A BAND OF THUNDERSTORMS...ESPECIALLY IN CENTRAL AND NORTH
CENTRAL NEBRASKA. MODEL OUTPUT STATISTICS INDICATE PROBABILITY/
COVERAGE OF 20-30 PERCENT IN THE SANDHILLS AND 30-40 PERCENT IN
CENTRAL AND NORTH CENTRAL NEBRASKA. THAT SEEMS REASONABLE. SURFACE
BASED CAPE IN CENTRAL AND NORTH CENTRAL NEBRASKA IS PRETTY HIGH AT
3500-4000J/KG WITH BULK SHEAR (0-6KM) AROUND 30KT. WITH STORM MOTION
240-260 AT 15-25KT...STORM RELATIVE HELICITY IS EXPECTED TO BE
110-200. SEVERE STORMS ARE POSSIBLE INTO THE EVENING...THOUGH WE
WILL NOT INCLUDE THE MENTION IN THE FORECAST FOR WEDNESDAY NIGHT.
A BOUNDARY LIFTING NORTH INTO SOUTHERN NEBRASKA WILL BRING THE
POSSIBILITY OF THUNDERSTORMS TO SOUTH CENTRAL AND SOUTHWEST NEBRASKA
THURSDAY NIGHT. AS THE BOUNDARY MAKES ITS WAY A LITTLE FARTHER NORTH
FRIDAY...THERE IS A POSSIBILITY OF THUNDERSTORMS IN CENTRAL AND
NORTHERN NEBRASKA.
FINALLY...SATURDAY NIGHT AND SUNDAY...A COOL FRONT COMES ACROSS
NEBRASKA AND THE PATTERN IS NOT AS FAVORABLE FOR STRONG CONVECTION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1239 PM CDT TUE AUG 19 2014
VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA THROUGH TONIGHT. ISOLATED THUNDERSTORMS MAY MOVE EASTWARD
INTO FAR WESTERN NEBRASKA THIS EVENING...AND SOME ISOLATED
DEVELOPMENT IS ALSO POSSIBLE LATE TONIGHT ACROSS NORTH CENTRAL
NEBRASKA. DUE TO THE ISOLATED NATURE...NO MENTION IS WARRANTED IN
THE OFFICIAL TAF FORECAST. WINDS WILL GENERALLY BE SOUTHEAST
AROUND 10 KTS THROUGH TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...TAYLOR
LONG TERM...SPRINGER
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1234 AM CDT TUE AUG 19 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 341 PM CDT MON AUG 18 2014
THE MAIN FORECAST ISSUE WILL BE THE POSSIBILITY OF SOME
THUNDERSTORM ACTIVITY IN THE FAR SOUTHERN CWA OVERNIGHT.
WEST NORTHWEST FLOW ALOFT IS FAIRLY WEAK AND A NEARLY STALLED
BOUNDARY ACROSS THE CWA CONTINUES TO DRIFT SOUTH TODAY. LITTLE IF
ANY DEVELOPMENT SHOULD DEVELOP ALONG THIS BOUNDARY TODAY INTO THIS
EVENING AS A FAIRLY HEALTHY CAP KEEPS THINGS QUIET...DESPITE
MODERATE INSTABILITY IN THE 1500 TO 2000 J/KG RANGE FOR CONVECTIVE
AVAILABLE POTENTIAL ENERGY. SOME SMALL POP-UPS ARE SHOWING UP JUST
NORTH OF THE CWA...BUT THERE SHOULD BE ENOUGH OF A CAP TO TAMP
MUCH FURTHER DEVELOPMENT IN THE NORTH.
LATER ON TONIGHT...A HEALTHY 40 TO 45 KT JET WILL DEVELOP OVER
KANSAS AND WILL CURVE EAST...MOSTLY LIKELY OVER NORTH CENTRAL
KANSAS. THIS WILL SET THE STAGE FOR SOME POTENTIAL LOW-LEVEL
CONVERGENCE ACROSS OUR SOUTHERN CWA IN NORTH CENTRAL KANSAS AND
FAR SOUTHERN NEBRASKA NEAR THE AFOREMENTIONED SURFACE BOUNDARY.
THIS COULD BE JUST ENOUGH SUPPORT FOR SOME SMALL HAIL AND GUSTY
WIND IN OUR FAR SOUTH AS WELL. THE HRRR IS TRENDING STRONGER WITH
SOME DEVELOPMENT OVER THE HIGH PLAINS THIS AFTERNOON...SUPPORTED
BY ANOTHER LOW-AMPLITUDE SHORTWAVE TROUGH. THIS COULD BE ENHANCED
BY THE DEVELOPING LOW-LEVEL JET IN KANSAS AS THIS POTENTIAL
CONVECTION HEADS SOUTH. THE NAM HAS BEEN ADVERTISING SOME ACTIVITY
IN THIS VICINITY FOR THE PAST COUPLE OF DAYS. THE PRUDENT ACTION
WOULD BE TO PUT A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS BACK
INTO THE FORECAST IN OUR SOUTH. OUR CHANCES OF RAIN ARE LARGELY
DEPENDENT ON INITIAL CONVECTION IN THE HIGH PLAINS WITHIN THE
STRONGLY UNSTABLE...YET STILL CAPPED ENVIRONMENT TO THE WEST AS
THE AFOREMENTIONED TROUGH ENTERS THE CENTRAL PLAINS. THE SREF
SOLUTIONS ARE ALSO COMING IN WITH STRONGER SIGNALS TOWARD
CONVECTION IN OUR SOUTH AS WELL.
FOR TUESDAY...KEEPING IT QUIET WITH THE THINKING THAT THERE
SHOULD BE ENOUGH OF A CAP FROM PRECLUDING DEVELOPMENT UNTIL THE
EVENING HOURS. HIGH PLAINS CONVECTION COULD DEVELOP DURING THE
DAY...BUT SHOULD HOLD OFF MAKING IT HERE UNTIL EVENING...WHEN A
LOW-LEVEL JET AXIS DEVELOPS JUST TO THE WEST OF THE CWA.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 341 PM CDT MON AUG 18 2014
GUIDANCE SUGGESTS UPPER TROPOSPHERIC RIDGING WILL EXIST OVER THE
CENTRAL CONUS TO START THE LONG TERM FORECAST PERIOD. THE RIDGE
AXIS IS EXPECTED TO SHIFT EAST SOMEWHAT BY THURSDAY OR FRIDAY
HOWEVER...ALLOWING FOR MORE OF A SOUTHWESTERLY UPPER TROPOSPHERIC
FLOW OVER OUR AREA LATE THIS WEEK INTO EARLY NEXT WEEK.
THE AXIS OF A 35-40KT LOWER TROPOSPHERIC JET STREAK...JUST ABOVE
THE BOUNDARY LAYER...IS EXPECTED DEVELOP FROM WESTERN KANSAS INTO
SOUTH CENTRAL NEBRASKA TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING.
THERMAL ADVECTION ALONG THIS AXIS APPEARS AS THOUGH IT WILL BE
SUFFICIENT FOR PRECIPITATION PRODUCTION ACROSS NORTHEASTERN
PORTIONS OF OUR CWA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE
NAM...OPERATIONAL GFS AND EC. WENT AHEAD WITH 20-30% POPS ACROSS
OUR NORTHEAST TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING AS A
RESULT.
ON OVERALL LACK IN OMEGA SHOULD THEN PROVIDE DRY CONDITIONS TO
OUR AREA THROUGH MUCH OF THE DAY WEDNESDAY. BY LATE WEDNESDAY
AFTERNOON HOWEVER...THE NAM AND OPERATIONAL GFS BOTH SUGGEST
CONVECTION WILL INITIATE OVER THE CENTRAL HIGH PLAINS...AND THEN
MOVE EAST INTO OUR AREA WEDNESDAY EVENING AND OVERNIGHT. GIVEN
THIS...WENT AHEAD WITH 20-30% POPS ACROSS MUCH OF THE CWA
WEDNESDAY EVENING AND NIGHT.
ALTHOUGH OMEGA IS EXPECTED TO REMAIN WEAK THROUGH THE DAY
THURSDAY AS WELL...FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE
CWA...PER THE NAM AND OPERATIONAL GFS...SUGGEST A NEARLY DRY
ADIABATIC TEMPERATURE PROFILE WILL BE REALIZED FROM THE SURFACE TO
JUST ABOVE 700MB ACROSS MUCH OF THE CWA...THUS ALLOWING CONVECTIVE
TEMPERATURE READINGS TO BE REACH AND PROVIDING FOR ISOLATED
THUNDERSTORM DEVELOPMENT. THIS IS A SOLUTION ALSO SUPPORTED BY QPF
FIELDS FROM THE NAM...OPERATIONAL GFS AND EC. GIVEN ALL
THIS...WENT AHEAD WITH ~20% POPS ACROSS MUCH OF THE CWA THURSDAY
AFTERNOON AND EVENING.
HEADING INTO THURSDAY NIGHT AND BEYOND...GUIDANCE SUGGESTS
MULTIPLE UPPER TROPOSPHERIC PERTURBATIONS COULD MOVE OVER THE
CENTRAL PLAINS AS THE SOUTHWESTERLY UPPER TROPOSPHERIC FLOW
INTENSIFIES. ALLBLEND RESPONDED BY PROVIDING 20-50% POPS TO MANY
AREAS ACROSS THE CWA THURSDAY NIGHT THROUGH MONDAY...AND THESE
POPS WERE LEFT UNCHANGED FOR THE MOST PART.
FORECAST PROXIMITY SOUNDINGS FROM THE NORTHEASTERN CWA...PER THE
NAM AND OPERATIONAL GFS...SUGGEST STORM-ACCESSIBLE POTENTIAL
ENERGY WILL NOT EXCEED 200-300J/KG TUESDAY NIGHT INTO EARLY
WEDNESDAY MORNING AND THUS...WILL HOLD OFF FROM ANY MENTION OF
SEVERE WEATHER TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING.
CONVECTION ALONG THE CENTRAL HIGH PLAINS WEDNESDAY AFTERNOON AND
EVENING WILL LIKELY HAVE THE CAPABILITY TO BE STRONG...BUT THERE
IS CONSIDERABLE UNCERTAINTY AS TO HOW LONG THIS CONVECTION WILL BE
ABLE TO MAINTAIN ITS INTENSITY AS IT MOVES EAST INTO OUR AREA.
GIVEN THIS UNCERTAINTY...WILL HOLD OFF FROM ANY MENTION OF SEVERE
WEATHER ACROSS OUR AREA WEDNESDAY EVENING AND LET FUTURE SHIFTS
REEVALUATE. BEYOND WEDNESDAY EVENING...AT THIS TIME THERE ARE NO
OVERWHELMING SIGNALS OF A SIGNIFICANT SEVERE WEATHER OUTBREAK.
ALTHOUGH A FEW HIT AND MISS STRONG TO SEVERE STORMS PROBABLY
CANNOT BE RULED OUT...DUE TO THE UNCERTAINTY WILL LEAVE OUT ANY
MENTION OF SEVERE WEATHER WEDNESDAY NIGHT AND BEYOND.
LITTLE CHANGE IN THE LOWER TROPOSPHERIC AIR MASS SHOULD PROMOTE
SIMILAR TEMPERATURE READINGS FROM DAY TO DAY WEDNESDAY THROUGH
SATURDAY...WITH AFTERNOON HIGHS IN THE UPPER 80S AND 90S AND
OVERNIGHT LOWS IN THE 60S AND LOWER 70S EXPECTED FOR THE MOST
PART. BEYOND SATURDAY...GUIDANCE DOES SUGGEST A LOWER TROPOSPHERIC
BAROCLINIC ZONE WILL MOVE ACROSS THE AREA...THUS ALLOWING A COOLER
LOWER TROPOSPHERIC AIR MASS INTO THE REGION. AFTERNOON HIGHS IN
THE UPPER 70S TO MID 80S AND LOWS GENERALLY IN THE 60S ARE
CURRENTLY EXPECTED TO FINISH THE LONG TERM FORECAST PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1230 AM CDT TUE AUG 19 2014
THUNDERSTORMS ARE WELL SOUTH OF THE TAF SITES EARLY THIS MORNING.
MOSTLY CLEAR SKIES ARE EXPECTED THROUGH THE PERIOD. LIGHT WINDS
WILL TURN TO THE SOUTHEAST DURING THE DAY AS A SURFACE HIGH MOVES
OFF TO THE EAST.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...HEINLEIN
LONG TERM...BRYANT
AVIATION...JCB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
910 PM EDT WED AUG 20 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW
ALOFT WILL CROSS THE REGION THIS WEEK. A BACK DOOR COLD FRONT IS
FORECAST TO SLIP INTO THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 220 PM WEDNESDAY...
THE OVER ALL WEATHER PATTERN STILL CONSISTS OF RELATIVELY WEAK
NORTHWESTERLY FLOW ALOFT AND A BROAD TROUGH AT THE SURFACE. ONE
UPPER DISTURBANCE...ATTENDANT TO A SHORTWAVE CROSSING THE
APPALACHIANS...CLIPPED THE NORTHERN HALF OF THE AREA THIS
MORNING...BUT THE ASSOCIATED CONVECTION DIED AS IT MOVED INTO THE
TRIAD. A TRAILING DISTURBANCE IS EVIDENT IN WATER VAPOR AND RAP H5
ANALYSIS OVER SOUTHWEST VA AND NORTHEAST TN...AND IS PROGGED TO CROSS
THE AREA THIS EVENING. THE BEST INSTABILITY HAS DEVELOPED FROM THE
SANDHILLS TO THE WESTERN PIEDMONT WHERE HEATING WAS UNINHIBITED BY
MORNING STRATUS. WITHIN THE INSTABILITY AXIS...A ZONE OF LOW-LEVEL
CONVERGENCE ACROSS THE SANDHILLS HAS INITIATED SOME SLOW MOVING
SHOWERS AND ISOLATED STORMS FROM RAEFORD TO THE SOUTHEAST. THE
APPROACHING DISTURBANCE SHOULD HELP TO INITIATE SOME ADDITIONAL
CONVECTION THIS AFTERNOON...THOUGH THE HRRR HAS YET TO LATCH ONTO
ANY TREND IN THE NEAR TERM. EXPECT SHOWERS AND STORMS ARE MORE
LIKELY FROM THE TRIAD DOWN TO FAYETTEVILLE...WITH JUST A SLIGHT
CHANCE FROM THO TRIANGLE NORTHEAST. IF CONVECTION DOES FIRE...A
RIBBON OF 30KT EFFECTIVE DEEP SHEAR AT THE BASE OF THE UPPER TROUGH
WILL SUPPORT SOME STRONGER CLUSTERS OF STORMS CAPABLE OF PRODUCING
SMALL HAIL AND ISOLATED DAMAGING WIND GUSTS.
TONIGHT...FORECAST SOUNDINGS SHOW SOME STEEP L;APSE RATES ABOVE THE
NOCTURNAL INVERSION...BUT THERE ISNT A CLEAR MECHANISM TO FORCE ANY
PARCELS OVERNIGHT...SO WILL LEAVE POPS OUT OF THE FORECAST AFTER
03Z. FORECAST SOUNDINGS ALSO SHOW LESS LOW-LEVEL MOISTENING TONIGHT
WITHOUT THE NORTHEASTERLY FLOW WE`VE SEEN THE LAST COUPLE OF
NIGHT...AND THEREFORE LESS POTENTIAL FOR STRATUS. LOWS IN THE UPPER
60S AND LOWER 70S.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 305 PM WEDNESDAY...
MID-LEVEL RIDGING BUILDS OVER THE DEEP SOUTH ON THURSDAY...LEADING
TO WEAK HEIGHT RISES OVER THE CAROLINAS AND H85 TEMPS SURPASSING
20C. FORECAST SOUNDINGS SHOW DEEP MIXING WITH WESTERLY FLOW...AND
DRY ADIABATIC MIXING YIELDS HIGHS WILL INTO THE 90S...WITH A
CONSENSUS OF 93-97. MIXING SHOULD ALSO HELP KNOCK DEWPOINTS BACK A
FEW DEGREES...HELPING KEEP HEAT INDICES AT 100F OR LESS. MLCAPE OF
AROUND 1000 J/KG IS FORECAST...BUT FORCING APPEARS TO BE LIMITED TO
THE RESIDUAL/THERMAL TROUGH WHICH SETS UP OVER THE EASTERN PIEDMONT.
WILL KEEP POPS AS ISOLATED UNLESS. LOWS THURSDAY NIGHT IN THE LOWER
70S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 145 PM WEDNESDAY...
THE INITIAL LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING
UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH AN UPPER
TROUGH/CLOSED LOW OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER
NORTHWEST UPPER FLOW INTO EARLY NEXT WEEK. A BACKDOOR FRONT WILL
MOVE ACROSS THE AREA LATE FRIDAY THROUGH SATURDAY...WHICH WILL
PRODUCE OUR BEST CHANCE OF PRECIPITATION DUE TO LOW LEVEL LIFT FROM
THE COOL AIR ADVECTION POTENTIALLY AIDED BY MODEST UPPER LEVEL
SUPPORT. OUTSIDE OF THE SLIGHTLY INCREASED CONFIDENCE IN THIS EARLY
WEEKEND PERIOD... PRECIP CHANCES HINGE ON MESOSCALE DISTURBANCES
ALOFT WITHIN THE NORTHWEST FLOW...WHICH ARE JUST ABOUT IMPOSSIBLE TO
FORECAST THIS FAR IN ADVANCE. AS SUCH...WILL MAINTAIN SMALL CHANCE
POPS THROUGH MONDAY...AFTER WHICH THE UPPER RIDGE AXIS SHIFTS EAST
ENOUGH TO DAMPEN PRECIP CHANCES.
HEIGHTS AND LOW LEVEL THICKNESSES PEAKING FRIDAY ARE INDICATIVE OF
HIGHS REACHING THE MID 90S OVER MUCH OF THE AREA. THESE HEIGHTS FALL
AS THE UPPER TROF DEEPENS ALONG THE EAST COAST CONCURRENT WITH COOL
AIR ADVECTION BY LATER SATURDAY IN UNIFORM LOW LEVEL NORTHEAST FLOW.
HIGHS WILL BE IN TRANSITION SATURDAY...FROM MID 80S NORTH TO 90
SOUTH...AND BOTTOMING OUT IN THE UPPER 70S TO LOWER 80S SUNDAY AND
MONDAY AS DAMMING SETTLES DOWN THE EAST COAST. MORNING LOWS
INITIALLY IN THE LOWER 70S SATURDAY MORNING WILL GRADUALLY FALL INTO
THE LOW TO MID 60S BY TUESDAY MORNING.
THE UPPER RIDGE AXIS WILL SHIFT EAST ON TUESDAY...WITH DRIER AIR AND
GRADUAL MODIFICATION OF THE AIR MASS IN PLACE. HIGHS TUESDAY WILL BE
MOSTLY IN THE LOW TO MID 80S...WARMING TO MOSTLY MID 80S ON
WEDNESDAY.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 840 PM WEDNESDAY...
ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS HAVE GENERALLY
DISSIPATED ACROSS CENTRAL NC THIS EVENING. HOWEVER... A WEAKENING
CLUSTER OF SHOWERS AND STORMS COULD MOVE INTO WESTERN PORTIONS OF
CENTRAL NC... POSSIBLY AFFECTING KGSO/KINT VERY LATE THIS EVENING OR
AFTER MIDNIGHT. ANOTHER AREA OF SHOWERS AND STORMS MOVING SOUTHWARD
THROUGH VA MAY ALSO AFFECT PORTIONS OF THE AREA VERY LATE THIS
EVENING AND/OR AFTER MIDNIGHT... WITH KRDU AND KRWI STANDING THE
BEST CHANCE OF SEEING ANY OF THIS ACTIVITY. IN ADDITION TO THESE TWO
AREAS OF POTENTIAL CONVECTION MOVING INTO THE CENTRAL NC WE COULD
SEE AN ISOLATED SHOWER/STORM DEVELOP THIS EVENING INTO THE
OVERNIGHT... AS THE BOUNDARY LAYER IS EXPECTED TO ONLY SLOWLY
STABILIZE THIS EVENING/EARLY THURSDAY. OTHERWISE... EXPECT THE
CHANCES FOR LOW STRATUS AND LIFR FOG WILL BE LOWER TONIGHT WITH THE
LOW LEVEL FLOW BECOMING MORE WESTERLY TO NORTHWESTERLY. HOWEVER...
EXPECT WE MAY STILL HAVE AT LEAST SOME IFR TO MVFR VISBYS DURING THE
PRE-DAWN HOURS AT ALL SITES... WITH PERHAPS FOG PRONE KRWI AGAIN
DROPPING INTO THE LIFR RANGE. KRDU... HAD SUBSTANTIAL PRECIP FROM
THIS AFTERNOON... SO EXPECT WE WILL HAVE SOME IFR TO POSSIBLY LIFR
CONDITIONS THERE. ELSEWHERE MVFR VISBYS WILL BE FAVORED.... UNLESS
MORE PRECIP AFFECTS A GIVEN SITE.
ANY SUB-VFR CONDITIONS WILL AGAIN LIFT TO VFR BY MID TO LATE MORNING
AT THE LATEST... WITH THE PROSPECTS OF VFR CONDITIONS BY 13-15Z AT
ALL TAF SITES FOR THURSDAY MORNING. ISOLATED TO WIDELY SCATTERED
SHOWERS AND STORMS WILL BE POSSIBLE AGAIN ON THURSDAY ACROSS ALL OF
CENTRAL NC. HOWEVER... THE PROBABILITY AT A GIVEN SITE IS TOO LOW TO
INCLUDE IN THE TAFS AT THIS TIME.
OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS
AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD
FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING
ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLS
NEAR TERM...BLS
SHORT TERM...BLS
LONG TERM...MLM
AVIATION...BSD/BLS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1256 AM CDT TUE AUG 19 2014
.UPDATE...
ISSUED AT 1231 AM CDT TUE AUG 19 2014
OUT OF RESPECT FOR THE NAM...WHICH WAS UPGRADED LAST WEEK...AND
THE HIRES ARW...ISOLATED TO SCATTERED THUNDERSTORMS WERE EXPANDED
ON TUESDAY EVENING/NIGHT. THE MAIN FOCUS TONIGHT WILL BE ON
POSSIBLE FOG DEVELOPMENT THIS MORNING ALONG WITH THE POTENTIAL
FOR RAINFALL ON ALREADY SATURATED SOILS TUESDAY NIGHT THROUGH THE
WEEKEND.
UPDATE ISSUED AT 935 PM CDT MON AUG 18 2014
NO SIGNIFICANT UPDATES THIS EVENING. PRECIPITATION HAS ALL BUT
ENDED OVER EASTERN NORTH DAKOTA...THUS CLEAR TO PARTLY CLOUDY
SKIES EXPECTED TONIGHT WITH PATCHY FOG POSSIBLE AFTER MIDNIGHT.
CURRENT FORECAST LOWS IN THE 50S LOOK REASONABLE.
UPDATE ISSUED AT 638 PM CDT MON AUG 18 2014
ISOLATED THUNDERSHOWERS CONTINUE TO DISSIPATE ACROSS EASTERN
PORTIONS OF CENTRAL NORTH DAKOTA. HAVE REMOVED ALL EVENING POPS
EXCEPT FOR JUST A SLIGHT CHANCE FAR EAST THROUGH 9 PM. OTHERWISE
MOSTLY CLEAR SKIES TONIGHT WITH LIGHT WINDS. PREVIOUS FORECAST HAD
A MENTION OF PATCHY FOG AFTER MIDNIGHT...WHICH LOOKS GOOD.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 318 PM CDT MON AUG 18 2014
DIURNAL CONVECTION THROUGH SUNSET THIS EVENING AND FOG TONIGHT
HIGHLIGHT THE SHORT TERM.
DIURNAL SCATTERED CONVECTION IS EXPECTED TO REMAIN FOCUSED ACROSS
THE SOUTH CENTRAL AND JAMES RIVER VALLEY GIVEN RADAR AND SATELLITE
TRENDS THROUGH 1930 UTC...AND THE 16-17 UTC HRRR ITERATIONS.
MODEST INSTABILITY AND WEAK SHEAR ARE EXPECTED TO KEEP STORMS
BELOW SEVERE LIMITS. HOWEVER...THE NON SUPERCELL TORNADO OR
LANDSPOUT PARAMETER HAS A LOCAL MAXIMA ACROSS THE JAMES RIVER
VALLEY INTO THE SOUTHERN RED RIVER VALLEY WITH STEEP LOW LEVEL
LAPSE RATES AND ENVIRONMENTAL VORTICITY. THUS...WOULD NOT BE
SURPRISED BY A FUNNEL CLOUD REPORT.
FOR TONIGHT...WITH WEAK SURFACE HIGH PRESSURE IN PLACE...CLEAR
SKIES...LIGHT WINDS AND PLENTIFUL MOISTURE FROM WEEKEND RAINS...AREAS
OF FOG ARE POSSIBLE ACROSS MUCH OF THE AREA TONIGHT.
TUESDAY WILL BE THE ONLY DRY DAY IN THE FORECAST UNDER SHORTWAVE
RIDGING BEFORE A RETURN TO AN ACTIVE WEATHER PATTERN THROUGH THE
EXTENDED.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 318 PM CDT MON AUG 18 2014
A SLOW MOVING TROUGH EXTENDING FROM THE NORTHWEST TERRITORIES WILL
PRODUCE CHANCES FOR WIDESPREAD SHOWERS/THUNDERSTORMS FROM WEDNESDAY
INTO THE WEEKEND. CHANCES FOR PRECIPITATION WILL CONTINUE THROUGH
THE EXTENDED...AS UNSETTLED SOUTHWESTERLY FLOW REMAINS OVER THE
AREA.
HEAVY RAINFALL IS EXPECTED OVER WESTERN AND CENTRAL PORTIONS OF THE
STATE WEDNESDAY INTO THURSDAY...WITH ADDITIONAL RAINFALL THROUGH THE
WEEKEND. WESTERN AND CENTRAL AREAS HAVE ALREADY BEEN SATURATED WITH
ABUNDANT RAINFALL...FLOODING ISSUES REMAIN A CONCERN.
TEMPERATURES WILL NEAR AVERAGE FOR WEDNESDAY AND THURSDAY. A
COOLER AIRMASS BEGINS MOVING INTO THE AREA BY FRIDAY MORNING...HIGHS
WILL RANGE BETWEEN 10 AND 15 DEGREES BELOW AVERAGE THROUGH THE REST
OF THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1231 AM CDT TUE AUG 19 2014
AREAS OF FOG MAY DEVELOP THIS MORNING AND LAST UNTIL 13Z. KJMS HAS
THE BEST POTENTIAL FOR IFR BECAUSE OF RAINFALL THERE ON
MONDAY...SO VISIBILITY REDUCTIONS HELD TO MVFR AT KDIK/KISN WHERE
SOME REDUCTION HAS ALREADY BEEN OBSERVED. THUNDERSTORMS ARE
POSSIBLE AFTER 00Z AT KISN/KMOT/KDIK.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SCHECK
SHORT TERM...AYD
LONG TERM...AC
AVIATION...SCHECK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
819 PM EDT WED AUG 20 2014
.SYNOPSIS...
A FRONTAL ZONE WILL SETTLE INTO THE OHIO VALLEY THIS EVENING.
THIS FRONT WILL GRADUALLY LIFT NORTHEAST INTO THE GREAT LAKES
THROUGH THE WEEKEND. DISTURBANCES WILL INTERACT WITH A MOIST
AIRMASS TO PRODUCE SHOWERS AND THUNDERSTORMS AT TIMES THROUGH THE
PERIOD.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
CONVECTION THAT IS AFFECTING THE TRI-STATE REGION ATTM WASNT
HANDLED WELL BY THE MODELS. THE HRRR HAS TRIED TO DISSIPATE ALL
AFTERNOON. KEPT THE CONVECTION TOGETHER AND PUSHED IT THRU THE
OHIO RIVER COUNTIES LATE THIS AFTERNOON.
FIGURING OUT POPS FOR THE REST OF THE NIGHT IS TOUGH....SINCE THE
MODEL GUIDANCE DIDNT COVER THIS CURRENT CONVECTION WELL. THAT
MAKES IT HARD TO FIGURE OUT WHEN TO TRANSITION FROM THE RADAR TO
MODEL. DEVELOPED SOME PCPN IN THE TRI- STATE REGION BETWEEN
00-06Z ALONG A WEAK FRONT. THIS IS SIMILAR TO THE CMC/NAM
SOLUTION. THEN LET IT DISSIPATE AS FOCUS SHIFTS TO ENERGY TO OUR
NW.
LOWS TONIGHT WILL BE WARM AND MUGGY. TEMPERATURES WILL ONLY DROP INTO
THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
THERE IS A LARGE VARIATION IN MODEL SOLUTIONS FOR THURSDAY. PREFER
A NAM/CMC REGIONAL/HIRES-WRF SOLUTION WHICH DROPS H5 ENERGY INTO
THE REGION EARLY THURSDAY MORNING IN THE NW FLOW. THEY PUSH THE
BEST PCPN CHANCE ACROSS THE REGION DURING THE MORNING...AND EXIT
IT OUT OF THE EAST DURING THE AFTN.
THURSDAY NIGHT BETTER FORCING SHIFTS TO NRN OHIO AS CONVERGENCE
ALONG A LIFTING WARM FRONT MOVES ALSO. PUT HIGH CHANCE POPS IN THE
NORTHERN COUNTIES WITH DECREASING POPS DOWN TO THE SW.
ON FRIDAY...ADDITIONAL H5 ENERGY TOPS THE RIDGE AND DROPS SE
ACROSS THE REGION. THIS WILL HELP DEVELOP DAYTIME CONVECTION...BUT
CENTRAL OHIO WILL HAVE THE BEST CHANCE AT SEEING CONVECTION AS IT
IS CLOSER TO THE WARM FRONT.
CONVECTION TOMORROW WILL COMPLICATE THE HIGH TEMPERATURE FORECAST.
ONLY WENT LOWER 80S IN THE NW COUNTIES SINCE THE CONVECTION SHOULD
LIMIT HEATING THERE. SOUTHERN COUNTIES SHOULD BE ABLE TO MAKE THE
MID TO UPPER 80S. AFTER DROPPING DOWN TO ONLY AROUND 70 THURSDAY
NIGHT...FRIDAY IS LOOKING LIKE A HOT AND HUMID DAY. OHIO RIVER
COUNTIES SHOULD SEE TEMPERATURES PUSH INTO THE LOWER 90S WITH
DEWPOINTS IN THE LOWER 70S. THIS WILL PUSH HEAT INDICES OVER 100.
WILL CONTINUE TO HIGHLIGHT THE THREAT IN THE HWO.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AT 12Z ON SATURDAY...THE 20.12Z ECMWF AND GFS ARE VERY GOOD
AGREEMENT ON THE LARGE SCALE PATTERN WITH AN AMPLIFIED FLOW PATTERN
OVER THE LOWER 48. A DEEP CLOSED LOW SHOULD BE OVER ID/MT WITH A
STRONG SUBTROPICAL RIDGE EXTENDING NORTHEAST FROM A 593DM HIGH OVER
ALABAMA. ANOMALOUS MOISTURE WILL STILL BE IN PLACE WITH PWAT FROM
1.5 TO 2.0 STANDARD DEVIATIONS ABOVE CLIMO. THROUGH THE WEEKEND THE
STRONG CLOSED LOW WILL SWING NORTHEAST INTO THE NRN HIGH PLAINS AND
EVENTUALLY INTO SASK...WHILE THE RIDGE EXPANDS NORTHEASTWARD INTO
TN/ARK. DESPITE WEAK FORCING...CONTINUED NORTHERLY/NORTHWESTERLY
FLOW AROUND THE RIDGE...THE PRESENCE OF A WEAK SURFACE TROUGH...AND
ANOMALOUS MOISTURE SHOULD CONTINUE TO ALLOW FOR STRONG DAYTIME
INSTBY BOTH SAT AND SUN. THE POTENTIAL FOR ONE MORE CLUSTERS OF SSE
PROPAGATING STORM CLUSTERS WILL CONTINUE THROUGH THE WEEKEND. GIVEN
THE MAGNITUDE OF INSTBY...EVEN WITH WEAKENING FLOW WITH TIME...THERE
COULD BE STRONG/SEVERE STORM THREAT ON EITHER OF THESE DAYS IF A
ORGANIZED COLD POOL COULD FORM. GETTING INTO MONDAY-TUESDAY...THE
RIDGE CONTINUES TO BUILD WITH HEAT/HUMIDITY. FLOW BECOMES VERY LIGHT
THROUGH THE BULK OF THE TROPOSPHERE AND IT BECOMES QUESTIONABLE IF
COVERAGE OF DAYTIME/EVE STORMS WARRANTS MENTION. RIGHT NOW HAVE RUN
15-25% RAIN CHANCES BOTH OF THESE DAYS...AND THAT MAY BE TOO HIGH.
INTO WEDNESDAY...SOME HINTS OF HEIGHT FALLS WHICH MAY ALLOW A LITTLE
STRONGER FLOW OR A WEAK SHORTWAVE TROUGH TO CROSS THE GREAT LAKES.
SO A BETTER STORM THREAT THEN...HOWEVER AT THIS TIME RANGE THIS IS A
VERY LOW CONFIDENCE FORECAST GIVEN CONDITIONAL NATURE OF THE RIDGE
BUCKLING.
SO ALL IN ALL...HAVE TENDED TO FOCUS RAIN CHANCES NEAR PEAK HEATING
INTO THE EVENING AND ALLOW FOR SOME DRY NIGHTS/EARLY MORNINGS. FLY
IN OINTMENT WILL BE ANY FORWARD PROPAGATING MCS THAT SURVIVES
THROUGH THE NIGHT...ORIGINATING TO OUR NORTHWEST AND FALLING DOWN
NNWLY FLOW EITHER SATURDAY MORNING OR SUNDAY MORNING. LOW CONFIDENCE
STORM CHANCE...BUT HIGH CONFIDENCE WARM/HUMID PATTERN IS THE STORY
FOR THE SAT-WED TIMEFRAME.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
SHOWERS AND THUNDERSTORMS HAVE EXITED THE AREA AND EXPECT DRY
CONDITIONS ACROSS THE TAF SITES THIS EVENING AND FOR MOST OF THE
OVERNIGHT HOURS. A DISTURBANCE WILL APPROACH THE AREA LATE IN THE
OVERNIGHT HOURS AND INTO THE DAYTIME MORNING HOURS ON THURSDAY.
HAVE A VCTS MENTION AT ALL TAF SITES FOR AWHILE DURING THIS TIME.
ADDED IN A TEMPO TSRA MENTION AT ALL AREA TAF SITES EXCEPT KCVG
AND KLUK.
THERE IS SOME QUESTION ON HOW LONG THE SHOWERS AND THUNDERSTORMS
WILL LINGER INTO THE AFTERNOON AND IF THERE WILL BE ADDITIONAL
DEVELOPMENT. EXPECT ANY ADDITIONAL DEVELOPMENT TO EXIT THE TAF
SITES BY THE END OF THE TAF PERIOD.
ADDITIONAL PRECIPITATION WILL START TO WORK INTO THE KCVG TAF AT
THE END OF THAT TAF PERIOD DUE TO THE LONGER TAF PERIOD. IN
ADDITION SOME FOG WILL BE POSSIBLE AT KCVG AND KLUK OVERNIGHT DUE
TO THE PREVIOUS RAINFALL AT THOSE LOCATIONS.
OUTLOOK...THUNDERSTORMS POSSIBLE THURSDAY EVENING THROUGH
SUNDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...SITES/SNYDER
NEAR TERM...SITES
SHORT TERM...SITES
LONG TERM...BINAU
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
359 PM EDT TUE AUG 19 2014
.SYNOPSIS...
LOW PRESSURE OVER LAKE MICHIGAN WILL SLOWLY MOVE TO THE EASTERN
GREAT LAKES THROUGH THURSDAY...PUSHING A WEAK COLD FRONT SOUTH
ACROSS THE AREA. HIGH PRESSURE WILL BUILD OVER LAKE ERIE BEHIND THIS
SYSTEM THURSDAY NIGHT...SHIFTING TO THE EASTERN GREAT LAKES ON
FRIDAY. A WARM FRONT WILL LIFT NORTH ACROSS THE AREA ON FRIDAY AND
SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
SHOWERS AND THUNDERSTORMS CONTINUE TO FILL IN ACROSS SW LOWER
MICHIGAN INTO INDIANA AHEAD OF A LOW PRESSURE SYSTEM LOCATED OVER
LAKE MICHIGAN. THIS REGION IS ALSO LOCATED AHEAD OF AN UPPER LEVEL
LOW SPINNING OVER THE WESTERN GREAT LAKES. THE SOUTHERN PORTION OF
THIS COMPLEX IS THE REMNANTS OF A LONG LIVED MCS THAT TRACKED OUT OF
MISSOURI THIS MORNING AND IS NOW MERGING WITH THE CONVECTION
DEVELOPING ALONG THE FRONT. STORM MOTION THIS AFTERNOON IS TO THE
NORTHEAST...ALTHOUGH THE CLUSTER OVER MICHIGAN IS SHOWING A TENDANCY
TO SLOWLY SINK SOUTH WITH TIME. IT LOOKS LIKE THE CLUSTER MOVING OUT
OF INDIANA WILL APPROACH THE TOLEDO AREA TOWARDS 6 PM. A SEVERE
THUNDERSTORM WATCH IS IN EFFECT FOR AREAS JUST WEST AND NORTH OF
TOLEDO AND THE WATCH MAY NEED TO BE EXPANDED IN NW OHIO IF
THUNDERSTORMS CAN MAINTAIN STRENGTH. THUS FAR THE GREATEST THREAT
HAS BEEN HEAVY RAIN WHERE STORMS HAVE BEEN TRAINING IN MICHIGAN WITH
NO REPORTS OF SEVERE WEATHER. AS OF 330 PM...NO WARNINGS HAVE BEEN
ISSUED WITH THE CONVECTION IN NRN INDIANA WHICH IS STARTING TO
OUTPACE THE FRONT. THERE IS SUFFICIENT INSTABILITY WITH ML CAPES
AROUND 1500 J/KG FOR STRONG TO SEVERE STORMS BUT SHEAR IS LACKING.
CORRIDOR OF DEEPER MOISTURE WILL CONTINUE TO MOVE NORTHEAST AHEAD OF
THE SURACE AND UPPER LEVEL LOW OVERNIGHT AND SHOWERS AND
THUNDERSTORMS ARE EXPECTED MOST AREAS. STORMS SHOULD WEAKEN AS WE
LOSE DIURNAL HEATING OVERNIGHT AND MAY BE MAINLY SHOWERS EAST OF
I-77 BY MORNING. DEWPOINTS/HUMIDITY WILL CONTINUE TO INCREASE
OVERNIGHT WHICH WILL KEEP TEMPERATURES MILD TONIGHT. LOWS ARE
FORECAST TO DROP INTO THE MID 60S.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/...
NEARLY VERTICALLY STACKED UPPER LEVEL AND SURFACE LOW WILL BE OVER
THE CENTRAL GREAT LAKES ON WEDNESDAY. A MOIST AND UNSTABLE AIRMASS
WILL RESIDE WITHIN THE AREA OF SOUTHERLY FLOW AHEAD OF THE SURFACE
LOW ACROSS MAINLY NE OHIO AND NW PA. CAPES ARE EXPECTED TO INCREASE
TO AROUND 2500 J/KG WITH SEVERAL MECHANISMS FOR CONVECTIVE INITIATION
DURING THE AFTERNOON. STORMS WILL FIRE DURING THE AFTERNOON AS THE
LOW SLOWLY MOVES EASTWARD. HIGHER RESOLUTION MODELS ALSO SHOW SOME
CONVERGENCE DOWNWIND OF LAKE ERIE THAT WILL SET UP SOUTH OF I-90.
LARGE SCALE FORCING WILL ALSO INCREASE DURING THE LATE AFTERNOON AS
A 35 KNOT MID-LEVEL JET STREAK MOVES THROUGH THE NORTHWESTERLY FLOW
ON THE BACK SIDE OF THE TROUGH. ALL OF THIS COMBINES TO MAKE
THUNDERSTORMS LIKELY ON THURSDAY ACROSS AT LEAST THE EASTERN HALF OF
THE FORECAST AREA. LESS CERTAIN IS IF ANYTHING CAN FIRE ACROSS NW
OHIO AHEAD OF THE JET STREAK WHICH CAN NOT BE ENTIRELY RULED OUT SO
WILL LEAVE A LOW POP IN THE NW OHIO. WHATEVER BREAKS EXIST IN THE
CLOUDS TO START THE DAY IN NE OHIO/NW PA WILL FILL IN QUICKLY AS
DIURNAL HEATING INCREASES...WHILE A GOOD DEAL OF SUN IS EXPECTED IN
THE DRIER AIR IN NW OHIO. HIGHS WILL RANGE FROM 77-85 AND WILL BE
HIGHEST IN THE WEST WHERE THEY WILL RECEIVE MORE SUN.
WEDNESDAY NIGHT WILL BE MOSTLY DRY AS WEAK COLD FRONT PUSHES SOUTH
WITH NEGATIVE THETA-E ADVECTION THROUGH THE COLUMN. WEAK HIGH
PRESSURE ALSO BUILDS IN BEHIND THE DEPARTING SURFACE LOW WHICH
SHOULD REDUCE CHANCES FOR PRECIPITATION DOWNWIND OF LAKE ERIE IN NE
OH/NW PA ON THURSDAY.
FARTHER SOUTH...SCATTERED THUNDERSTORMS ARE EXPECTED TO FIRE ALONG
STALLED BOUNDARY ON THURSDAY. THURSDAY NIGHT COULD ALSO BE ACTIVE
ACROSS THE SW HALF OF THE FORECAST AREA AS ENERGY MOVES AROUND THE
BUILDING RIDGE THURSDAY NIGHT. THIS WILL BE FOLLOWED BY A WARM FRONT
STARTING TO LIFT BACK NORTH ON FRIDAY. THIS WILL BE THE BEGINNING OF
THE WARMING TREND FOR THE WEEKEND...WITH HIGHS REACHING THE MID TO
UPPER 80S IN THE WEST ON FRIDAY.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE LONG TERM BEGINS ON SATURDAY WITH BOTH THE GFS AND ECMWF SHOWING
AN UPPER LEVEL HIGH CENTERED OVER THE SOUTHEASTERN STATES. A RIDGE
WILL EXTEND NORTH INTO THE CENTRAL LAKES. NOT MUCH CHANGES THROUGH
SUNDAY INTO MONDAY EXCEPT THAT LOW PRESSURE MOVING THROUGH SOUTHERN
CANADA WILL TILT THE AXIS OF THE RIDGE EAST A BIT HOWEVER IT SHOULD
STILL REMAIN WEST OF THE AREA. TUESDAY THE LOW MOVES TO NORTHERN
ONTARIO FLATTENING THE RIDGE ACROSS THE LAKES. GIVEN THE RIDGE
POSITION...WOULD EXPECT THAT ANY CONVECTION THAT GOES OVER THE TOP
OF THE RIDGE WILL DESCEND ON THE REGION FROM THE NORTH. FOR NOW
THOUGH IT WOULD BE FAIRLY DIFFICULT TO ANTICIPATE TIMING OTHER THAT
A SMALL CHANCE POP FOR AFTERNOON AND EARLY EVENING CONVECTION. WILL
HAVE A SLIGHT CHANCE POP IN FOR THE OVERNIGHT AND EARLY MORNING
PERIODS. ALSO...GUIDANCE SUGGESTS MORE CLOUD COVER THEN SEEMS
REASONABLE GIVEN THE RIDGE SO LOWERED CLOUD PERCENTAGES TO GET
PARTLY CLOUDY THROUGH MOST OF THE PERIOD. TEMPS AT OR ABOVE
NORMAL.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
LOW PRESSURE MOVING INTO THE CENTRAL LAKES THIS AFTERNOON WITH
CONVECTION NOW FROM SRN/CENTRAL LWR MI ACRS SRN LAKE MI INTO NRN
INDIANA. ACTIVITY TIMES INTO NWRN OHIO 22Z-24Z. USING TIMING FROM
THE HRRR AS WELL AS SPC MODELS...CONVECTION TIMES INTO KCLE AROUND
00Z AND KERI/KCAK/YNG 02Z-04Z. OVERNIGHT AFTER THE CONVECTION
EXPECT CONDITIONS WILL DROP TO MVFR/IFR IN LOWER CIGS AND MIST/FOG
GIVEN THE ADDED LOW LEVEL MOISTURE AS WELL AS MOISTURE ASSOCIATED
WITH THE LOW AFFECTING THE REGION.
OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THROUGH
FRIDAY.
&&
.MARINE...
LOW PRESSURE OVER THE GREAT LAKES WILL CONTINUE THROUGH TONIGHT AND
TUESDAY INTO MID WEEK...EVENTUALLY REACHING WESTERN NEW YORK BY
THURSDAY MORNING. FLOW AROUND THE LOW IS NOT PARTICULARLY STRONG SO
AM EXPECTING VARIABLE BUT GENERALLY LIGHT WINDS THROUGH THE PERIOD
RESULTING IN WAVES OF 2 FEET OR LESS ON THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC
SHORT TERM...KEC
LONG TERM...TK
AVIATION...TK
MARINE...TK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
151 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A WARM FRONT WILL LIFT NORTHWARD INTO NORTHERN OHIO TODAY AS LOW
PRESSURE TRACKS INTO NORTHERN MICHIGAN TONIGHT. AS THE LOW
PROGRESSES SLOWLY EASTWARD INTO THURSDAY IT WILL DRAG A COLD FRONT
ACROSS THE REGION. THIS FRONTAL BOUNDARY WILL REMAIN A FACTOR INTO
THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
DEWPOINTS ARE INCREASING INTO THE UPPER 60S ACROSS WESTERN OHIO.
SHOWERS AND THUNDERSTORMS ARE FILLING IN ALONG THE WARM FRONT IN
WESTERN MICHIGAN...EXTENDING WESTWARD ACROSS LAKE MICHIGAN TOWARDS
THE MCS IN ILLINOIS. IT WILL TAKE SEVERAL HOURS YET FOR THIS
ACTIVITY TO REACH NORTHWEST OHIO. SLOWED DOWN THE CHANCE OF
THUNDERSTORMS A LITTLE BIT MORE FOR LATER TODAY AND REMOVED THE
SLIGHT CHANCE OF THUNDERSTORMS FROM NORTHEAST OHIO. INSTABILITY IS
INCREASING ACROSS INDIANA WITH ML CAPE VALUES NEAR 2000 J/KG. AT
THIS TIME THERE STILL APPEARS TO BE A SEVERE WEATHER THREAT FOR
NW OHIO INTO THIS EVENING AS THIS ACTIVITY APPROACHES. THE CIRRUS
SHIELD IS STARTING TO OUTPACE THE CONVECTION THOUGH SO WE WILL
HAVE TO SEE WHAT EFFECT THAT HAS ON INSTABILITY LATER TODAY.
PREVIOUS DISCUSSION...WE WILL CONTINUE TO WATCH THE UPSTREAM
CLUSTER OF THUNDERSTORMS MOVING INTO ILLINOIS. THIS ACTIVITY IS
ONGOING IN AN AREA OF BETTER INSTABILITY WITH A WEAK JET STREAK IN
THE MID-LEVEL FLOW NEAR 500MB. MID-LEVEL LAPSE RATES ARE FAIRLY
STEEP ACROSS ILLINOIS AHEAD OF THIS FEATURE SO COULD SEE THIS
ACTIVITY HOLD TOGETHER AND STRENGTHEN AS IT CONTINUES EASTWARD.
CONVECTION WILL LIKELY ALSO DEVELOP ACROSS SW MICHIGAN/INDIANA IN
THE VICINITY OF THE OUTFLOW BOUNDARY FROM THIS MORNING AND IT WILL
BE INTERESTING TO SEE HOW THIS INTERACTS WITH THE LARGER COMPLEX
TO THE WEST. CHANCES FOR SHOWERS AND THUNDERSTORMS ACROSS NW OHIO
WILL INCREASE LATE THIS AFTERNOON...LIKELY AFTER 4 PM...THEN
SPREAD EASTWARD TONIGHT. NW OHIO REMAINS IN THE SLIGHT RISK FOR
SEVERE STORMS AS INSTABILITY AND LARGE SCALE ASCENT INCREASES
AHEAD OF THE UPPER LOW APPROACHING LAKE MICHIGAN.
ORIGINAL DISCUSSION... A WARM FRONT WILL SLOWLY LIFT NORTHWARD ACROSS
OHIO TODAY. LIFT OVER THIS BOUNDARY...AFTERNOON HEATING AND
INCREASING SHEAR ASSOCIATED WITH A 5H 40 KNOT JET WILL HELP TO
DEVELOP THUNDERSTORMS OVER SOUTHERN MICHIGAN SOUTHWARD INTO
INDIANA THIS AFTERNOON. A FEW OF THESE THUNDERSTORMS WILL BE
CAPABLE OF PRODUCING STRONG DAMAGING WINDS AND LARGE HAIL AS THEY
MOVE TOWARD NW OHIO LATE THIS AFTERNOON INTO THE EVENING. EASTERN
AREAS WILL TAKE MOST OF THE DAY TO MOISTEN UP SO THE THREAT OF
THUNDERSTORMS IS MINIMAL.
IT WILL BE ANOTHER WARM DAY WITH HIGHS SIMILAR TO YESTERDAYS.
ACTUALLY IT WILL PROBABLY BE A DEGREE OR TWO WARMER AT MOST
LOCATIONS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
THERE WILL BE A THREAT OF SEVERE THUNDERSTORMS UNTIL SHORTLY AFTER
SUNSET THIS EVENING. BEYOND THAT IT APPEARS THERE WILL BE AN AREA
OF SHOWERS AND THUNDERSTORMS THAT MOVE FROM WEST TO EAST ACROSS
THE REGION WITH A WEAKENING COLD FRONT. IT WILL LIKELY TAKE UNTIL AFTER
MIDNIGHT FOR THE RAIN TO REACH EXTREME NE OHIO INTO NW PA. THIS
WEAK FRONT WILL END UP BEING A FACTOR IN THE WEATHER THROUGH THE
SECOND HALF OF THE WEEK. IT IS DIFFICULT TO SAY WHERE THIS
BOUNDARY WILL BE LOCATED EACH DAY WITH IT POTENTIALLY BEING PUSHED
SOUTH OF THE COUNTY WARNING AREA BY THURSDAY. SINCE THERE IS SO
MUCH UNCERTAINTY WE WILL KEEP LOW CHANCES GOING IN THE FORECAST AT
THIS TIME. HOWEVER WITH INCREASING HEIGHTS OVER THE REGION WE MAY
BE ABLE TO SHUT THE RAIN CHANCES OFF FASTER THAN WHAT THE CURRENT
FORECAST INDICATES.
IT WILL REMAIN WARM THROUGH THE SHORT TERM WITH HIGHS REMAINING
SLIGHTLY ABOVE SEASONAL AVERAGES.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
UPPER LEVEL HIGH PRESSURE WILL ENCOMPASS THE ENTIRE EASTERN UNITED
STATES BY SATURDAY AND BUILD GRADUALLY EAST THROUGH THE PERIOD.
HOWEVER...ATMOSPHERE IS A BIT ACTIVE AS SMALL WEAK SHORTWAVE TROUGHS
ROTATE OVER THE NORTH SIDE OF THE HIGH INTO THE FORECAST AREA
THROUGH MUCH OF THE EXTENDED PERIOD. EXPECTING SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS JUST ABOUT EACH DAY. THIS IS ALSO IN
RESPONSE TO SOME WARM AIR ADVECTION TAKING PLACE AND THE CLOSE
PROXIMITY OF A STATIONARY FRONT. SO...THE TEMPERATURES AND
PRECIPITATION THREAT IS ALL DEPENDENT ON WHERE THE STATIONARY
FRONT IS AT...AT ANY GIVEN MOMENT. SOME PLACES IN THE WEST COULD
HIT 90 DEGREES FOR HIGHS ON SATURDAY WHILE COOLER TEMPERATURES
OCCUR THE FURTHER EAST ONE GOES.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
LOW PRESSURE MOVING INTO THE CENTRAL LAKES THIS AFTERNOON WITH
CONVECTION NOW FROM SRN/CENTRAL LWR MI ACRS SRN LAKE MI INTO NRN
INDIANA. ACTIVITY TIMES INTO NWRN OHIO 22Z-24Z. USING TIMING FROM
THE HRRR AS WELL AS SPC MODELS...CONVECTION TIMES INTO KCLE AROUND
00Z AND KERI/KCAK/YNG 02Z-04Z. OVERNIGHT AFTER THE CONVECTION
EXPECT CONDITIONS WILL DROP TO MVFR/IFR IN LOWER CIGS AND MIST/FOG
GIVEN THE ADDED LOW LEVEL MOISTURE AS WELL AS MOISTURE ASSOCIATED
WITH THE LOW AFFECTING THE REGION.
OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THROUGH
FRIDAY.
&&
.MARINE...
NOT MUCH TO TALK ABOUT ON THE LAKE OVER THE NEXT 5 DAYS. WINDS ARE
EXPECTED TO BE RELATIVELY LIGHT AND THEREFORE TRANSLATE TO WAVES OF
GENERALLY ONE FOOT OR LESS THROUGH THE PERIOD.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...KEC/MULLEN
SHORT TERM...MULLEN
LONG TERM...LOMBARDY
AVIATION...TK
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1225 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A VERY WARM...HUMID AND ACTIVE WEATHER PATTERN CONTINUES. AN UPPER
LEVEL DISTURBANCE CROSSES TONIGHT. A WARM FRONT SETS UP TO THE WEST
OF THE AREA WEDNESDAY NIGHT...AND THEN MOVES INTO THE AREA ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SENT A QUICK UPDATE TO ADJUST POPS PER LATEST RADAR IMAGES SHOWING
WEAK CONVECTION ACROSS THE SOUTH AND WESTERN SLOPES OF WV AROUND
NOON. EXPECT THIS ACTIVITY TO INCREASE IN COVERAGE AND INTENSITY
PER HIGH RESOLUTION MODELS INDICATING INCREASE IN SFC BASED CAPE
FROM 1600-2000 J/KG BY THE RAP AND NAM MODELS. THESE VALUES LOOKS
REASONABLE COMPARED WITH DEWPOINTS IN THE LOWER 70S ACROSS THE
AREA. PWATS IN THE ORDER OF 1.4 INCHES...ACCORDING WITH
SATELLITE DERIVED PRODUCTS...AND DIFFERENTIAL HEATING FROM BREAKS
IN THE SKY WILL ALLOW CONVECTION TO STRENGTHEN INTO ISOLATED
THUNDERSTORMS THIS AFTERNOON AND TONIGHT. MODELS ALSO SHOW A
SHORTWAVE AT 5 BRINGING A VORTICITY MAXIMA ACROSS THE AREA BY 06Z
WEDNESDAY. THIS FEATURE WILL ENHANCE CONVECTION TONIGHT. INCREASED
POPS TO LIKELY WITH THIS LATEST FEATURE.
HOURLY TEMPERATURES ADJUSTED AS WELL PER LATEST SFC OBS.
PREVIOUS DISCUSSION BELOW...
630 AM UPDATE...
FCST ON TRACK.
PREV DISCN...
ISOLATED SHOWERS WITH PINHEAD DOWNPOURS CONTINUE OVER SE PORTIONS OF
THE FCST AREA IN THE WAKE OF AN UPPER LEVEL S/W TROUGH AND SFC LOW
THAT CROSSED MON. LOW LEVEL WNW UPSLOPE FLOW AND HIGH PW VALUES ARE
LIKELY HELPING TO MAINTAIN THIS ACTIVITY...WHICH SHOULD WANE A BIT
FURTHER BUT PERHAPS NOT ALTOGETHER DISAPPEAR LATER THIS MORNING.
OTHERWISE LOW CLOUDS WILL BE SLOW TO MIX OUT THIS MORNING...AS THE
FOG SLOWLY THINS.
THE AREA REMAINS IN A VERY MOIST AND HUMID AIR MASS TODAY WITH
INSTABILITY LEADING TO DIURNAL CONVECTION THIS AFTERNOON. THE LACK
OF FORCING SUGGESTS THERE WILL NOT BE MUCH COVERAGE...BUT THE LIGHT
FLOW THROUGH H5 SPELLS SLOW MOVEMENT ON ANYTHING THAT DOES STAND UP.
UPPER LEVEL S/W TROUGH CROSSES TONIGHT...ITS TIMING SLOWER COMPARED
WITH PREVIOUS RUNS. ANY SEVERE POTENTIAL WITH IT WILL BE MAINLY W
OF THE AREA BECAUSE OF THIS...ALTHOUGH STRONG STORMS CAN MAKE IT
INTO THE MIDDLE OHIO VALLEY BEFORE SUNSET. STRATUS AND FOG WILL
LIKELY FOLLOW THE SHOWERS AND THUNDERSTORMS LATE TONIGHT.
MINOR CHANGES TO TEMPERATURES IN LIGHT OF LATEST BIAS CORRECTED
GUIDANCE...A LITTLE WARMER TODAY WITH THE SLOWER SYSTEM...AND
ANOTHER VERY WARM AND MUGGY NT TONIGHT.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
UNSETTLED WEATHER IN THE SHORT TERM PERIOD. UPPER LOW/TROUGH MOVING
EAST...WITH A MAINLY NWLY FLOW ALOFT...WITH SEVERAL UPPER
DISTURBANCES MOVING INTO THE REGION. THIS...COMBINED WITH THE HUMID
AIRMASS IN PLACE...WILL KEEP A MENTION OF SHOWERS AND THUNDERSTORMS
IN THE FORECAST. PW VALUES DURING THE PERIOD WILL REMAIN RATHER
HIGH...GENERALLY 1.5 INCHES OR HIGHER...THUS CONTINUING THE THREAT
FOR HEAVY DOWNPOURS. IN ADDITION...COULD BE STORMS ON THE STRONGER
SIDE WEDNESDAY/WEDNESDAY NIGHT...PARTICULARLY SOUTHEAST OHIO AND
EASTERN KY WHERE BETTER CAPE/SHEAR WILL EXIST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
USED WPC THINKING WITH SOME TWEAKS. NORTHWEST UPPER LEVEL FLOW IS
ANTICIPATED THROUGH MUCH OF THE PERIOD...WITH HIGH PRESSURE TRYING
TO BUILD IN LATE. AT THE SURFACE...A NW-SE ORIENTED FRONT SHOULD
BE LOCATED NEARBY THROUGH MUCH OF THE PERIOD.
WPC TEMPS LOOKED GOOD AND WERE GENERALLY USED.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
LOW STRATUS DOMINATES EARLY THIS MORNING. IT TOOK THE LOWERING OF
IT TO REALIZE DENSE FOG AT HTS AND IT LOOKED LIKE THE SAME THING
WAS HAPPENING AT EKN AS 11Z APPROACHED. THE SAME MAY HAPPEN AT
OTHER SITES AS WE NEAR AND CROSS THE START OF THE 1912/2012 TAF
PERIOD. THE FOG WILL THIN INTO AN MVFR MIST BY MID MORNING BEFORE
DISAPPEARING ALTOGETHER...BUT IT WILL TAKE MUCH OF NOT ALL OF THE
MORNING FOR THE STRATUS TO LIFT THROUGH AND THEN ABOVE THE MVFR
RANGE. MVFR STRATOCU MAY HANG ON INTO THE AFTERNOON IN THE
MOUNTAINS.
THE PROBLEM TONIGHT WILL BE THUNDERSTORMS...ALTHOUGH THIS FCST IS
ALSO A BIT UNCERTAIN. THE STORMS SHOULD FIRE UP IN THE MIDDLE OHIO
VALLY AS A SYSTEM APPROACHES FROM THE NW LATER TODAY. THE STORMS
WILL MOVE QUICKLY SEWD THROUGH THE MIDDLE OHIO VALLEY AND THEN THE
CENTRAL APPALACHIANS TONIGHT.
POST RAIN STRATUS AND FOG ARE LIKELY TO FORM IN THE WAKE OF THE
SHOWERS AND THUNDERSTORMS BY DAWN WED.
LIGHT AND VARIABLE SFC FLOW WILL BECOME LIGHT SW TONIGHT...WHILE
LIGHT NW FLOW ALOFT BECOMES LIGHT W THIS AFTERNOON AND THEN LIGHT SW
TONIGHT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY...
FORECAST CONFIDENCE: LOW TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF LIFTING AND DISSIPATION OF LOW
STRATOCU...STRATUS AND FOG THIS MORNING MAY VARY. TIMING OF AND
CONDITIONS IN THUNDERSTORMS LATE TODAY AND TONIGHT MAY VARY. IFR IS
POSSIBLE RIGHT BENEATH ANY THUNDERSTORM LATE TODAY AND TONIGHT. THE
THUNDERSTORMS MAY ALSO PRODUCE STRONG WIND GUSTS IN THE MIDDLE OHIO
VALLEY THIS EVENING. TIMING AND EXTENT OF FOG AND STRATUS LATE
OVERNIGHT TONIGHT MAY ALSO VARY FROM FCST.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21
CRW CONSISTENCY L H M M M H H H H H H H
HTS CONSISTENCY M H H H H H H H H H H H
BKW CONSISTENCY H H H H H H M H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H M M M H H H H H H H H
AFTER 18Z WEDNESDAY...
IFR POSSIBLE IN ANY ROUND OF CONVECTION WED NT THROUGH FRI NT...AND
IN LATE NT/EARLY MORNING POST RAIN FOG AND STRATUS THROUGH SAT
MORNING.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/SL
NEAR TERM...ARJ/TRM
SHORT TERM...SL
LONG TERM...JSH
AVIATION...TRM
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
651 AM EDT TUE AUG 19 2014
.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF A WEAK FRONT WHICH
WILL APPROACH THIS AFTERNOON AND EVENING. THE FRONT WILL STALL
ALONG THE OHIO VALLEY WEDNESDAY...THEN GRADUALLY LIFT NORTHEAST
THROUGH THE END OF THE WEEK. DISTURBANCES TRACKING ALONG THE FRONT
WILL KEEP THE WEATHER UNSETTLED THROUGH AT LEAST FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO INCLUDE A DENSE FOG ADVISORY ACROSS THE SOUTHERN HALF
OF THE AREA WHERE THERE ARE QUITE A FEW OBSERVATIONS OF A QUARTER
MILE OR LESS. LIGHT FOG WILL EXIST ELSEWHERE.
PREVIOUS DISCUSSION...
FAIRLY WEAK FLOW PATTERN OVER THE EASTERN CONUS TODAY AS A
MID/UPPER LEVEL TROUGH DIGS INTO THE WESTERN GREAT LAKES. A WEAK
SURFACE BOUNDARY ALONG THE OHIO RIVER WILL LIFT NORTH IN RESPONSE
TO LOW PRESSURE ATTENDANT TO THE MID AND UPPER LEVEL FEATURE. A
FEW RUNS OF THE RAP AND HRRR TRIED TO DEVELOP A FEW SHOWERS WITH
THE BOUNDARY THIS MORNING...BUT HAVE KEPT THE FORECAST DRY BASED
ON LATEST OBSERVATIONS. AS DAYTIME HEATING BUILDS...SOME
CONVECTION MAY START DEVELOPING AROUND THE MIDDAY HOURS...BUT THIS
WILL BE ISOLATED AT BEST. THE MAIN FOCUS WILL BE TO OUR WEST...AS
SHOWERS AND STORMS FIRE ALONG A PREFRONTAL TROUGH. EXACT TIMING IS
STILL IN QUESTION...BUT SOME STORMS COULD ARRIVE IN WEST CENTRAL
OHIO BY LATE AFTERNOON. WILL DISCUSS THESE STORMS FURTHER IN THE
SHORT TERM SECTION. BASED ON THE TEMPERATURE TRENDS FROM
MONDAY...WE COULD WARM PRETTY NICELY WITH A LACK OF PRECIPITATION
DURING PEAK HEATING. WENT A LITTLE ABOVE GUIDANCE FOR MOST... IN
THE MID TO UPPER 80S AND INCREASING DEW POINTS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
AN AREA OF SCATTERED TO NUMEROUS STORMS WILL BE CROSSING THE AREA
DURING THE EVENING HOURS. MODERATE INSTABILITY...LIKELY BETWEEN
1-2K J/KG...WILL HAVE DEVELOPED DURING THE AFTERNOON. RICHER LOW
LEVEL MOISTURE LOOKS LIKE IT WILL STAY TO THE SOUTHWEST OF OUR
AREA. WHILE THERE IS SOME INCREASED MID LEVEL FLOW ASSOCIATED WITH
THE DIGGING TROUGH...THE HIGHEST BULK SHEAR VALUES ARE GENERALLY
TO OUR SOUTHWEST AS WELL. WITH THAT SAID...THERE ARE ENOUGH
INGREDIENTS IN PLACE FOR AT LEAST SOME STRONGER
STORMS...ESPECIALLY WEST OF I-75 WHERE SPC HAS HOISTED A SLIGHT
RISK. A WEAKENING TREND IS EXPECTED THROUGH THE EVENING AS
INSTABILITY IS LOST...BUT THE TIMING WILL BE IMPORTANT TO WHEN
THIS OCCURS. INTERESTINGLY...THE LATEST MODEL RUNS ARE FOCUSING
THE GREATEST COVERAGE NORTH OF THE OHIO RIVER...LIKELY CLOSEST TO
THE STRONGER FORCING...SO ADJUSTED THE POPS ACCORDINGLY. THE NAM
SEEMS A LITTLE TOO BULLISH IN DEVELOPING ADDITIONAL CONVECTION
ALONG THE WEAK SURFACE FRONT. BASED ON DEEP LAYER
MOISTURE...EXPECT A DRYING TREND TOWARD WEDNESDAY MORNING. MUGGY
LOWS IN THE UPPER 60S TO AROUND 70.
FORCING ASSOCIATED WITH THE UPPER LEVEL TROUGH WILL BE PUSHING
EAST ON WEDNESDAY...BUT THERE ARE SOME INDICATIONS THE SURFACE
FRONT COULD REACTIVATE IN CENTRAL OHIO AROUND MIDDAY BEFORE
PUSHING EAST. THE TAIL END OF THE FRONT WILL STALL ACROSS NORTHERN
KENTUCKY...WARRANTING CHANCE POPS THERE AS WELL. HIGH TEMPERATURES
IN THE MID 80S.
FROM WEDNESDAY NIGHT THROUGH FRIDAY...MID AND UPPER LEVEL RIDGING
WILL BEGIN BUILDING ACROSS THE CENTER OF THE COUNTRY AS TROUGHING
DIGS INTO THE PACIFIC NORTHWEST. THIS WILL PLACE THE OHIO VALLEY
UNDER INCREASING NORTHWEST FLOW WITH POTENTIAL FOR SOUTHEASTWARD
DIVING DISTURBANCES. A NW-SE LOW LEVEL BAROCLINIC ZONE WILL
TIGHTEN AS WELL WITH MOISTURE POOLED ALONG IT. THE CHANCE OF
STORMS WILL INCREASE WEDNESDAY NIGHT IN THE TRI STATE
AREA...OVERSPREADING THE REST OF THE REGION ON THURSDAY. FRIDAY
WILL REMAIN UNSETTLED AS THE CORRIDOR OF FORCING MOVES ONLY
SLIGHTLY NORTHEAST IN RESPONSE TO THE BUILDING RIDGE. EXPECT
INCREASINGLY MUGGY CONDITIONS WITH HIGHS GENERALLY IN THE MID TO
UPPER 80S AND LOWS ON EITHER SIDE OF 70.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MID/UPPER LEVEL RIDGING OVER THE CENTRAL UNITED STATES WILL SHIFT
SLOWLY EAST TOWARD THE LOWER OHIO VALLEY THROUGH THE WEEKEND. PCPN
CHANCES SHOULD THEN BECOME MORE SUPPRESSED AS WE PROGRESS THROUGH
THE WEEKEND AS THE RIDGE BUILDS IN FROM THE SOUTHWEST. SHORT WAVE
ENERGY MOVING ACROSS THE GREAT LAKES WILL BEGIN TO WEAKEN THE
RIDGE FROM THE NORTH LATE IN THE PERIOD...EVENTUALLY HELPING TO
PUSH A COLD FRONT DOWN TOWARD OUR AREA. THIS MAY ALLOW FOR A
CHANCE OF PCPN TOWARD THE END OF THE PERIOD ON MONDAY...BUT GIVEN
THE MODEL DIFFERENCES WITH THE TIMING...WILL MAINTAIN A DRY
FORECAST AT THIS POINT.
TEMPERATURES WILL BE SOMEWHAT DEPENDENT ON THE TIMING AND DEGREE OF
THUNDERSTORM ACTIVITY THROUGH LATE IN THE WEEK. HOWEVER...WITH THE
HIGH BUILDING IN FROM THE SOUTHWEST...GENERALLY EXPECT A GRADUAL
WARMING TREND TO ABOVE NORMAL HIGH TEMPERATURES THROUGH THE WEEKEND.
OVERNIGHT LOWS WILL REMAIN ON THE WARM SIDE TOO WITH LOWS MOSTLY IN
THE UPPER 60S TO AROUND 70 DEGREES.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
FOG AND STRATUS ARE PREVALENT AT THE SOUTHERN TERMINALS OF
KCVG...KLUK...AND KILN THIS MORNING. IFR/LIFR/VLIFR CONDITIONS
SHOULD IMPROVE BETWEEN 14Z AND 17Z AS THE FOG AND STRATUS BURN OFF
AND BECOME REPLACED BY BKN CUMULUS DECK.
OTHERWISE...A LOW PRESSURE SYSTEM WILL MOVE EAST ACROSS THE
WESTERN GREAT LAKES TODAY AND TONIGHT. FORECAST MODELS INDICATE
THAT PERHAPS A PREFRONTAL TROF AXIS WILL TRAIL SOUTH FROM THIS
LOW AND WILL PUSH EAST INTO OUR REGION LATE THIS AFTERNOON INTO
THE EARLY MORNING HOURS OF WEDNESDAY. THIS TROF AXIS WILL THEN BE
FOLLOWED BY A WEAK COLD FRONT LATE TONIGHT INTO WEDNESDAY MORNING.
DAYTIME INSTABILITY AND ENOUGH SHEAR/CONVERGENCE WITH THE
PREFRONTAL TROF AXIS SHOULD BRING AT LEAST SCATTERED SHOWERS AND
THUNDERSTORMS TO THE TERMINALS THIS EVENING INTO THE EARLY MORNING
HOURS OF WEDNESDAY. HAVE PLACED VCTS/CB DESCRIPTORS AT THE SITES
WHEN THIS IS MOST LIKELY TO OCCUR...BETWEEN 00Z AND 09Z. THE WEAK
COLD FRONT WILL FOLLOW BEHIND THE TROF LATE TONIGHT...BUT IT
APPEARS CONVERGENCE WILL BE WEAKER AND INSTABILITY WILL HAVE WANED
SOME...SO COVERAGE APPEARS LESS WITH THIS BOUNDARY.
OUTLOOK...THUNDERSTORMS POSSIBLE WEDNESDAY THROUGH SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR OHZ070>073-
077>082-088.
KY...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ089>100.
IN...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR INZ050-058-
059-066-073>075-080.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...SNYDER
SHORT TERM...SNYDER
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
531 AM EDT TUE AUG 19 2014
.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF A WEAK FRONT WHICH
WILL APPROACH THIS AFTERNOON AND EVENING. THE FRONT WILL STALL
ALONG THE OHIO VALLEY WEDNESDAY...THEN GRADUALLY LIFT NORTHEAST
THROUGH THE END OF THE WEEK. DISTURBANCES TRACKING ALONG THE FRONT
WILL KEEP THE WEATHER UNSETTLED THROUGH AT LEAST FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO INCLUDE A DENSE FOG ADVISORY ACROSS THE SOUTHERN HALF
OF THE AREA WHERE THERE ARE QUITE A FEW OBSERVATIONS OF A QUARTER
MILE OR LESS. LIGHT FOG WILL EXIST ELSEWHERE.
PREVIOUS DISCUSSION...
FAIRLY WEAK FLOW PATTERN OVER THE EASTERN CONUS TODAY AS A
MID/UPPER LEVEL TROUGH DIGS INTO THE WESTERN GREAT LAKES. A WEAK
SURFACE BOUNDARY ALONG THE OHIO RIVER WILL LIFT NORTH IN RESPONSE
TO LOW PRESSURE ATTENDANT TO THE MID AND UPPER LEVEL FEATURE. A
FEW RUNS OF THE RAP AND HRRR TRIED TO DEVELOP A FEW SHOWERS WITH
THE BOUNDARY THIS MORNING...BUT HAVE KEPT THE FORECAST DRY BASED
ON LATEST OBSERVATIONS. AS DAYTIME HEATING BUILDS...SOME
CONVECTION MAY START DEVELOPING AROUND THE MIDDAY HOURS...BUT THIS
WILL BE ISOLATED AT BEST. THE MAIN FOCUS WILL BE TO OUR WEST...AS
SHOWERS AND STORMS FIRE ALONG A PREFRONTAL TROUGH. EXACT TIMING IS
STILL IN QUESTION...BUT SOME STORMS COULD ARRIVE IN WEST CENTRAL
OHIO BY LATE AFTERNOON. WILL DISCUSS THESE STORMS FURTHER IN THE
SHORT TERM SECTION. BASED ON THE TEMPERATURE TRENDS FROM
MONDAY...WE COULD WARM PRETTY NICELY WITH A LACK OF PRECIPITATION
DURING PEAK HEATING. WENT A LITTLE ABOVE GUIDANCE FOR MOST... IN
THE MID TO UPPER 80S AND INCREASING DEW POINTS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
AN AREA OF SCATTERED TO NUMEROUS STORMS WILL BE CROSSING THE AREA
DURING THE EVENING HOURS. MODERATE INSTABILITY...LIKELY BETWEEN
1-2K J/KG...WILL HAVE DEVELOPED DURING THE AFTERNOON. RICHER LOW
LEVEL MOISTURE LOOKS LIKE IT WILL STAY TO THE SOUTHWEST OF OUR
AREA. WHILE THERE IS SOME INCREASED MID LEVEL FLOW ASSOCIATED WITH
THE DIGGING TROUGH...THE HIGHEST BULK SHEAR VALUES ARE GENERALLY
TO OUR SOUTHWEST AS WELL. WITH THAT SAID...THERE ARE ENOUGH
INGREDIENTS IN PLACE FOR AT LEAST SOME STRONGER
STORMS...ESPECIALLY WEST OF I-75 WHERE SPC HAS HOISTED A SLIGHT
RISK. A WEAKENING TREND IS EXPECTED THROUGH THE EVENING AS
INSTABILITY IS LOST...BUT THE TIMING WILL BE IMPORTANT TO WHEN
THIS OCCURS. INTERESTINGLY...THE LATEST MODEL RUNS ARE FOCUSING
THE GREATEST COVERAGE NORTH OF THE OHIO RIVER...LIKELY CLOSEST TO
THE STRONGER FORCING...SO ADJUSTED THE POPS ACCORDINGLY. THE NAM
SEEMS A LITTLE TOO BULLISH IN DEVELOPING ADDITIONAL CONVECTION
ALONG THE WEAK SURFACE FRONT. BASED ON DEEP LAYER
MOISTURE...EXPECT A DRYING TREND TOWARD WEDNESDAY MORNING. MUGGY
LOWS IN THE UPPER 60S TO AROUND 70.
FORCING ASSOCIATED WITH THE UPPER LEVEL TROUGH WILL BE PUSHING
EAST ON WEDNESDAY...BUT THERE ARE SOME INDICATIONS THE SURFACE
FRONT COULD REACTIVATE IN CENTRAL OHIO AROUND MIDDAY BEFORE
PUSHING EAST. THE TAIL END OF THE FRONT WILL STALL ACROSS NORTHERN
KENTUCKY...WARRANTING CHANCE POPS THERE AS WELL. HIGH TEMPERATURES
IN THE MID 80S.
FROM WEDNESDAY NIGHT THROUGH FRIDAY...MID AND UPPER LEVEL RIDGING
WILL BEGIN BUILDING ACROSS THE CENTER OF THE COUNTRY AS TROUGHING
DIGS INTO THE PACIFIC NORTHWEST. THIS WILL PLACE THE OHIO VALLEY
UNDER INCREASING NORTHWEST FLOW WITH POTENTIAL FOR SOUTHEASTWARD
DIVING DISTURBANCES. A NW-SE LOW LEVEL BAROCLINIC ZONE WILL
TIGHTEN AS WELL WITH MOISTURE POOLED ALONG IT. THE CHANCE OF
STORMS WILL INCREASE WEDNESDAY NIGHT IN THE TRI STATE
AREA...OVERSPREADING THE REST OF THE REGION ON THURSDAY. FRIDAY
WILL REMAIN UNSETTLED AS THE CORRIDOR OF FORCING MOVES ONLY
SLIGHTLY NORTHEAST IN RESPONSE TO THE BUILDING RIDGE. EXPECT
INCREASINGLY MUGGY CONDITIONS WITH HIGHS GENERALLY IN THE MID TO
UPPER 80S AND LOWS ON EITHER SIDE OF 70.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MID/UPPER LEVEL RIDGING OVER THE CENTRAL UNITED STATES WILL SHIFT
SLOWLY EAST TOWARD THE LOWER OHIO VALLEY THROUGH THE WEEKEND. PCPN
CHANCES SHOULD THEN BECOME MORE SUPPRESSED AS WE PROGRESS THROUGH
THE WEEKEND AS THE RIDGE BUILDS IN FROM THE SOUTHWEST. SHORT WAVE
ENERGY MOVING ACROSS THE GREAT LAKES WILL BEGIN TO WEAKEN THE
RIDGE FROM THE NORTH LATE IN THE PERIOD...EVENTUALLY HELPING TO
PUSH A COLD FRONT DOWN TOWARD OUR AREA. THIS MAY ALLOW FOR A
CHANCE OF PCPN TOWARD THE END OF THE PERIOD ON MONDAY...BUT GIVEN
THE MODEL DIFFERENCES WITH THE TIMING...WILL MAINTAIN A DRY
FORECAST AT THIS POINT.
TEMPERATURES WILL BE SOMEWHAT DEPENDENT ON THE TIMING AND DEGREE OF
THUNDERSTORM ACTIVITY THROUGH LATE IN THE WEEK. HOWEVER...WITH THE
HIGH BUILDING IN FROM THE SOUTHWEST...GENERALLY EXPECT A GRADUAL
WARMING TREND TO ABOVE NORMAL HIGH TEMPERATURES THROUGH THE WEEKEND.
OVERNIGHT LOWS WILL REMAIN ON THE WARM SIDE TOO WITH LOWS MOSTLY IN
THE UPPER 60S TO AROUND 70 DEGREES.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
FIRST OF ALL...PARTLY CLOUDY TO MOSTLY CLEAR SKIES OVERNIGHT
ALONG WITH AMPLE LOW LEVEL MOISTURE AND LIGHT TO CALM WINDS WILL
RESULT IN PATCHY TO AREAS OF FOG AT THE TERMINALS. THE WORST
CONDITIONS ARE EXPECTED AT THE SOUTHERN TERMINALS WHERE MOISTURE
IS THE HIGHEST. HAVE IFR CONDITIONS AT KILN...KCVG AND KLUK...WITH
SOME LIFR/VLIFR POSSIBLE AT KILN AND AND KLUK. FOG SHOULD BURN OFF
BY 14Z.
A LOW PRESSURE SYSTEM WILL MOVE EAST ACROSS THE WESTERN GREAT
LAKES TODAY AND TONIGHT. FORECAST MODELS INDICATE THAT A
PREFRONTAL TROF AXIS WILL TRAIL SOUTH FROM THIS LOW AND WILL PUSH
EAST INTO OUR REGION LATE THIS AFTERNOON INTO THE EARLY MORNING
HOURS OF WEDNESDAY. THIS TROF AXIS WILL THEN BE FOLLOWED BY A
WEAK COLD FRONT LATE TONIGHT INTO WEDNESDAY MORNING.
FOR LATER TODAY AND TONIGHT...DAYTIME INSTABILITY AND ENOUGH
SHEAR/CONVERGENCE WITH THE PREFRONTAL TROF AXIS SHOULD BRING AT
LEAST SCATTERED SHOWERS AND THUNDERSTORMS TO THE TERMINALS THIS
EVENING INTO THE EARLY MORNING HOURS OF WEDNESDAY. HAVE PLACED
VCTS/CB DESCRIPTORS AT THE SITES WHEN THIS IS MOST
LIKELY TO OCCUR...BETWEEN 00Z AND 06Z. THE WEAK COLD FRONT WILL
FOLLOW BEHIND THE TROF LATE TONIGHT...BUT IT APPEARS CONVERGENCE
WILL BE WEAKER AND INSTABILITY WILL HAVE WANED SOME...SO COVERAGE
APPEARS LESS WITH THIS BOUNDARY.
OUTLOOK...THUNDERSTORMS POSSIBLE WEDNESDAY THROUGH SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR OHZ070>073-
077>082-088.
KY...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ089>100.
IN...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR INZ050-058-
059-066-073>075-080.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...SNYDER
SHORT TERM...SNYDER
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
448 AM EDT TUE AUG 19 2014
.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF A WEAK FRONT WHICH
WILL APPROACH THIS AFTERNOON AND EVENING. THE FRONT WILL STALL
ALONG THE OHIO VALLEY WEDNESDAY...THEN GRADUALLY LIFT NORTHEAST
THROUGH THE END OF THE WEEK. DISTURBANCES TRACKING ALONG THE FRONT
WILL KEEP THE WEATHER UNSETTLED THROUGH AT LEAST FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
FAIRLY WEAK FLOW PATTERN OVER THE EASTERN CONUS TODAY AS A MID/UPPER
LEVEL TROUGH DIGS INTO THE WESTERN GREAT LAKES. A WEAK SURFACE BOUNDARY
ALONG THE OHIO RIVER WILL LIFT NORTH IN RESPONSE TO LOW PRESSURE
ATTENDANT TO THE MID AND UPPER LEVEL FEATURE. A FEW RUNS OF THE
RAP AND HRRR TRIED TO DEVELOP A FEW SHOWERS WITH THE BOUNDARY THIS
MORNING...BUT HAVE KEPT THE FORECAST DRY BASED ON LATEST
OBSERVATIONS. AS DAYTIME HEATING BUILDS...SOME CONVECTION MAY
START DEVELOPING AROUND THE MIDDAY HOURS...BUT THIS WILL BE
ISOLATED AT BEST. THE MAIN FOCUS WILL BE TO OUR WEST...AS SHOWERS
AND STORMS FIRE ALONG A PREFRONTAL TROUGH. EXACT TIMING IS STILL
IN QUESTION...BUT SOME STORMS COULD ARRIVE IN WEST CENTRAL OHIO BY
LATE AFTERNOON. WILL DISCUSS THESE STORMS FURTHER IN THE SHORT
TERM SECTION. BASED ON THE TEMPERATURE TRENDS FROM MONDAY...WE
COULD WARM PRETTY NICELY WITH A LACK OF PRECIPITATION DURING PEAK
HEATING. WENT A LITTLE ABOVE GUIDANCE FOR MOST... IN THE MID TO
UPPER 80S AND INCREASING DEW POINTS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
AN AREA OF SCATTERED TO NUMEROUS STORMS WILL BE CROSSING THE AREA
DURING THE EVENING HOURS. MODERATE INSTABILITY...LIKELY BETWEEN
1-2K J/KG...WILL HAVE DEVELOPED DURING THE AFTERNOON. RICHER LOW
LEVEL MOISTURE LOOKS LIKE IT WILL STAY TO THE SOUTHWEST OF OUR
AREA. WHILE THERE IS SOME INCREASED MID LEVEL FLOW ASSOCIATED WITH
THE DIGGING TROUGH...THE HIGHEST BULK SHEAR VALUES ARE GENERALLY
TO OUR SOUTHWEST AS WELL. WITH THAT SAID...THERE ARE ENOUGH
INGREDIENTS IN PLACE FOR AT LEAST SOME STRONGER
STORMS...ESPECIALLY WEST OF I-75 WHERE SPC HAS HOISTED A SLIGHT
RISK. A WEAKENING TREND IS EXPECTED THROUGH THE EVENING AS
INSTABILITY IS LOST...BUT THE TIMING WILL BE IMPORTANT TO WHEN
THIS OCCURS. INTERESTINGLY...THE LATEST MODEL RUNS ARE FOCUSING
THE GREATEST COVERAGE NORTH OF THE OHIO RIVER...LIKELY CLOSEST TO
THE STRONGER FORCING...SO ADJUSTED THE POPS ACCORDINGLY. THE NAM
SEEMS A LITTLE TOO BULLISH IN DEVELOPING ADDITIONAL CONVECTION
ALONG THE WEAK SURFACE FRONT. BASED ON DEEP LAYER
MOISTURE...EXPECT A DRYING TREND TOWARD WEDNESDAY MORNING. MUGGY
LOWS IN THE UPPER 60S TO AROUND 70.
FORCING ASSOCIATED WITH THE UPPER LEVEL TROUGH WILL BE PUSHING
EAST ON WEDNESDAY...BUT THERE ARE SOME INDICATIONS THE SURFACE
FRONT COULD REACTIVATE IN CENTRAL OHIO AROUND MIDDAY BEFORE
PUSHING EAST. THE TAIL END OF THE FRONT WILL STALL ACROSS NORTHERN
KENTUCKY...WARRANTING CHANCE POPS THERE AS WELL. HIGH TEMPERATURES
IN THE MID 80S.
FROM WEDNESDAY NIGHT THROUGH FRIDAY...MID AND UPPER LEVEL RIDGING
WILL BEGIN BUILDING ACROSS THE CENTER OF THE COUNTRY AS TROUGHING
DIGS INTO THE PACIFIC NORTHWEST. THIS WILL PLACE THE OHIO VALLEY
UNDER INCREASING NORTHWEST FLOW WITH POTENTIAL FOR SOUTHEASTWARD
DIVING DISTURBANCES. A NW-SE LOW LEVEL BAROCLINIC ZONE WILL
TIGHTEN AS WELL WITH MOISTURE POOLED ALONG IT. THE CHANCE OF
STORMS WILL INCREASE WEDNESDAY NIGHT IN THE TRI STATE
AREA...OVERSPREADING THE REST OF THE REGION ON THURSDAY. FRIDAY
WILL REMAIN UNSETTLED AS THE CORRIDOR OF FORCING MOVES ONLY
SLIGHTLY NORTHEAST IN RESPONSE TO THE BUILDING RIDGE. EXPECT
INCREASINGLY MUGGY CONDITIONS WITH HIGHS GENERALLY IN THE MID TO
UPPER 80S AND LOWS ON EITHER SIDE OF 70.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MID/UPPER LEVEL RIDGING OVER THE CENTRAL UNITED STATES WILL SHIFT
SLOWLY EAST TOWARD THE LOWER OHIO VALLEY THROUGH THE WEEKEND. PCPN
CHANCES SHOULD THEN BECOME MORE SUPPRESSED AS WE PROGRESS THROUGH
THE WEEKEND AS THE RIDGE BUILDS IN FROM THE SOUTHWEST. SHORT WAVE
ENERGY MOVING ACROSS THE GREAT LAKES WILL BEGIN TO WEAKEN THE
RIDGE FROM THE NORTH LATE IN THE PERIOD...EVENTUALLY HELPING TO
PUSH A COLD FRONT DOWN TOWARD OUR AREA. THIS MAY ALLOW FOR A
CHANCE OF PCPN TOWARD THE END OF THE PERIOD ON MONDAY...BUT GIVEN
THE MODEL DIFFERENCES WITH THE TIMING...WILL MAINTAIN A DRY
FORECAST AT THIS POINT.
TEMPERATURES WILL BE SOMEWHAT DEPENDENT ON THE TIMING AND DEGREE OF
THUNDERSTORM ACTIVITY THROUGH LATE IN THE WEEK. HOWEVER...WITH THE
HIGH BUILDING IN FROM THE SOUTHWEST...GENERALLY EXPECT A GRADUAL
WARMING TREND TO ABOVE NORMAL HIGH TEMPERATURES THROUGH THE WEEKEND.
OVERNIGHT LOWS WILL REMAIN ON THE WARM SIDE TOO WITH LOWS MOSTLY IN
THE UPPER 60S TO AROUND 70 DEGREES.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
FIRST OF ALL...PARTLY CLOUDY TO MOSTLY CLEAR SKIES OVERNIGHT
ALONG WITH AMPLE LOW LEVEL MOISTURE AND LIGHT TO CALM WINDS WILL
RESULT IN PATCHY TO AREAS OF FOG AT THE TERMINALS. THE WORST
CONDITIONS ARE EXPECTED AT THE SOUTHERN TERMINALS WHERE MOISTURE
IS THE HIGHEST. HAVE IFR CONDITIONS AT KILN...KCVG AND KLUK...WITH
SOME LIFR/VLIFR POSSIBLE AT KILN AND AND KLUK. FOG SHOULD BURN OFF
BY 14Z.
A LOW PRESSURE SYSTEM WILL MOVE EAST ACROSS THE WESTERN GREAT
LAKES TODAY AND TONIGHT. FORECAST MODELS INDICATE THAT A
PREFRONTAL TROF AXIS WILL TRAIL SOUTH FROM THIS LOW AND WILL PUSH
EAST INTO OUR REGION LATE THIS AFTERNOON INTO THE EARLY MORNING
HOURS OF WEDNESDAY. THIS TROF AXIS WILL THEN BE FOLLOWED BY A
WEAK COLD FRONT LATE TONIGHT INTO WEDNESDAY MORNING.
FOR LATER TODAY AND TONIGHT...DAYTIME INSTABILITY AND ENOUGH
SHEAR/CONVERGENCE WITH THE PREFRONTAL TROF AXIS SHOULD BRING AT
LEAST SCATTERED SHOWERS AND THUNDERSTORMS TO THE TERMINALS THIS
EVENING INTO THE EARLY MORNING HOURS OF WEDNESDAY. HAVE PLACED
VCTS/CB DESCRIPTORS AT THE SITES WHEN THIS IS MOST
LIKELY TO OCCUR...BETWEEN 00Z AND 06Z. THE WEAK COLD FRONT WILL
FOLLOW BEHIND THE TROF LATE TONIGHT...BUT IT APPEARS CONVERGENCE
WILL BE WEAKER AND INSTABILITY WILL HAVE WANED SOME...SO COVERAGE
APPEARS LESS WITH THIS BOUNDARY.
OUTLOOK...THUNDERSTORMS POSSIBLE WEDNESDAY THROUGH SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...SNYDER
SHORT TERM...SNYDER
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
152 AM EDT TUE AUG 19 2014
.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN OHIO WILL MOVE EAST TO THE VIRGINIA
COAST BY TUESDAY MORNING. A STATIONARY FRONT ACROSS CENTRAL OHIO
WILL BE DRAWN SOUTH IN THE WAKE OF THE LOW. ANOTHER LOW WILL MOVE
INTO THE WESTERN GREAT LAKES OVERNIGHT AND EXPAND ACROSS THE
CENTRAL LAKES TUESDAY BRINGING THE FRONT BACK NORTH INTO THE AREA
AS A WARM FRONT. THE LOW WILL REMAIN IN THE AREA THROUGH MID WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
OVERNIGHT WE ARE EXPECTING DRY CONDITIONS. NOT SURE WHY HRRR KEEPS
ON AND OFF LIGHT SHRA/SPRINKLES OVER THE EAST THRU THE NIGHT. THIS
AREA IS WHERE THE MODELS HAVE THE DRIEST AIR SO IT DOES NOT SEEM TO
MAKE SENSE...UNLESS ITS TRYING TO INDICATE MID LEVEL ATTEMPTS AT
PRECIP/VIRGA.
MORE CLOUDS ON THE WAY FROM THE WEST OVERNIGHT ASSOCIATED WITH THE
LOW MOVING INTO THE WESTERN LAKES. EXPECTING THOSE AFTER MIDNIGHT IN
THE WEST ALONG WITH A SLIGHT CHANCE OF SHOWERS OR A THUNDERSTORM
TOWARD DAYBREAK. LOWS SHOULD BE IN THE LOWER 60S WITH A FEW UPPER
50S EAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
THE SOUTHERN OHIO LOW WILL HAVE REACHED THE VIRGINIA COAST BY
MORNING WITH THE NEXT LOW MOVING INTO/ THROUGH THE WESTERN LAKES.
THIS LOW WILL DOMINATE THE SHORT TERM PERIOD AS IT ROTATES THROUGH
THE GREAT LAKES REGION THROUGH MID WEEK. ALSO THE FRONT TO OUR
SOUTH WILL BEGIN MOVING NORTHEAST AS A WARM FRONT AS THE LOW
APPROACHES AND BY MORNING IT SHOULD EXTEND FROM NEAR CHICAGO TO
CINCINNATI. FOLLOWED THE SREF FOR PRECIP TIMING TUESDAY WHICH
BRINGS CHANCE POPS INTO THE WEST DURING THE MORNING...INCREASING
TO LIKELY BY MID DAY AS THE REST OF THE AREA INCREASES TO CHANCE
POPS. BY EARLY EVENING SPREAD THE LIKELY POPS FURTHER EAST ACROSS
THE CENTRAL COUNTIES...EVENTUALLY EXPANDING ACROSS THE REMAINDER
OF THE EAST LATE EVENING TO OVERNIGHT. WEDNESDAY MORNING THE UPPER
LOW WILL REMAIN STUCK OVER NRN MI WITH CONTINUED DIVERGENCE ACROSS
NRN OHIO/NWRN PA. AXIS OF DEEPEST MOISTURE WILL BE NEGATIVELY
TILTED FROM THE WESTERN LAKES TO PA AND NY. WILL KEEP HIGHEST POPS
ACROSS NERN OHIO AND NWRN PA WITH DECREASING CHANCES WEST. THE LOW
WILL WEAKEN AND MOVE TO PA/NY THURSDAY AS AN UPPER RIDGE AXIS
BUILDS INTO THE UPPER MIDWEST. STILL WILL LIKELY SEE SHOWERS AND
THUNDERSTORMS DURING THE DAY GIVEN THE CONTINUED MOISTURE AND
DAYTIME HEATING SO WILL CONTINUE WITH CHANCE POPS. TEMPS NEAR
NORMAL.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
UPPER LEVEL LOW MOVES OFF THE EAST COAST ON FRIDAY WITH THE UPPER
LEVEL RIDGE OVER THE MISSISSIPPI VALLEY SLOWLY EXPANDING EASTWARD
OVER THE WEEKEND. FRIDAY LOOKS LIKE A TRANSITION DAY AND COULD BE
ACTIVE WITH SHOWERS AND THUNDERSTORMS AS ENERGY RIDES AROUND THE
BUILDING RIDGE. BOTH THE ECMWF AND GFS TRY TO BUILD A STRONG RIDGE
OVER THE GREAT LAKES THIS WEEKEND AND EXTENDING NORTHEAST INTO
QUEBEC. THIS SHOULD LEAD TO DECREASING CHANCES OF SHOWERS AND
THUNDERSTORMS BOTH SATURDAY AND SUNDAY AS MID LEVELS WARM AND WARM
FRONT SHIFTS NORTH OF THE AREA. MODELS DO INDICATE SOME LINGERING
MOISTURE AND SOMEWHAT OF A BOUNDARY IN PLACE THOUGH SO WILL HOLD
ONTO LOW CHANCES OF SHOWERS AND THUNDERSTORMS IN ALL BUT THE EAST
WHERE A DRIER EASTERLY FLOW ON THE PERIPHERY OF HIGH PRESSURE TO THE
EAST SHOULD LIKELY MAINTAIN DRY CONDITIONS. STILL EXPECT A WARMING
TREND OVER THE WEEKEND BUT HAVE BACKED OFF A FEW DEGREES FOR NOW
WITH UNCERTAINTY IN CLOUD COVER.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
FORECAST THIS MORNING ALL HINGES ON TIMING OF THE THUNDERSTORM
COMPLEX THAT IS CURRENTLY OVER WISCONSIN. POTENTIAL EXISTS THAT
THE BULK OF THE THUNDERSTORM ACTIVITY WILL SCOOT EAST ACROSS
MICHIGAN INTO ONTARIO. SOME INSTABILITY WILL DEVELOP ACROSS
NORTHERN OHIO AND NORTHWEST PENNSYLVANIA AND THIS COULD HELP SOME
OF THE THUNDERSTORM ACTIVITY TO DEVELOP FURTHER SOUTH. WILL
CONTINUE WITH CURRENT FORECAST OF TIMING PRECIPITATION INTO THE
FORECAST AREA DURING THE AFTERNOON AND EVENING FROM THE COMPLEX.
WILL ALSO KEEP A MENTION OF SHOWERS AND THUNDERSTORMS FOR TONIGHT
AS WARM FRONTAL BOUNDARY AND ASSOCIATED MOISTURE MOVE EAST INTO
THE REGION.
OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THROUGH
FRIDAY.
&&
.MARINE...
LAKE ERIE IS LOCATED BETWEEN HIGH PRESSURE TO THE NORTH AND A WEAK
AREA OF LOW PRESSURE OVER THE OHIO VALLEY. NORTHEAST TO EAST WINDS
HAVE INCREASED TO AROUND 15 KNOTS OR SO ALONG MUCH OF THE SOUTH
SHORE OF THE LAKE...WITH WAVES OF 1 TO 3 FEET. THE HIGH WILL BUILD
TO THE EAST OVERNIGHT AND WINDS WILL DECREASE AS THE GRADIENT
RELAXES...SHIFTING TO EASTERLY AND THEN SOUTHEAST LATE.
AN AREA OF LOW PRESSURE WILL MOVE INTO THE WESTERN GREAT LAKES ON
TUESDAY THEN MOVE ACROSS LAKE ERIE ON WEDNESDAY BRINGING UNSETTLED
WEATHER. WINDS WILL GENERALLY REMAIN 15 KNOTS OR LESS AS THEY SHIFT
AROUND TO THE WEST BEHIND THIS SYSTEM. HIGH PRESSURE WILL RETURN ON
THURSDAY FOLLOWED BY A SLOW MOVING WARM FRONT THAT WILL LIFT NORTH
ACROSS THE LAKE OVER THE WEEKEND.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...ADAMS/TK
SHORT TERM...TK
LONG TERM...KEC
AVIATION...LOMBARDY
MARINE...KEC
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1129 PM EDT WED AUG 20 2014
.SYNOPSIS...
AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST
ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF
HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD
ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
STILL SOME WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ABOUT THE
STATE TONIGHT CENTRAL AREAS. THERE IS ONE PERSISTENT AND SLOW TO
DIE ORGANIZED AREA OF CONVECTION OVER ELK AND NORTHERN CLEARFIELD
COUNTIES TONIGHT. IT IS MOVING SLOWLY TO THE SOUTH AND EAST. IT
HAS HELD TOGETHER ON RADAR FOR HOURS AND COLD CLOUD AREA IMPLIES
IT HAS SOME LIFE LEFT. LOW-LEVEL VELOCITY DATA IMPLIES IT HAS A
COLD POOL WHICH WILL LIKELY ALLOW IT TO PERSIST FOR A FEW MORE
HOURS. SO WE HAD TO KEEP RAIN AND POPS 80 TO 90 PERCENT UP THERE.
THE HRRR SHOWS THIS SYSTEM SPLITTING AND GOING ACROSS CENTRAL PA
THROUGH 0700 UTC. COULD SEE ISOLATED THUNDER AND RAIN AREAS IF THE
23Z HRRR IS CORRECT.
MOST OTHER AREAS UNAFFECTED BY THIS CONVECTION SHOULD SEE FOG
DEVELOP. PERHAPS PATCHY DENSE FOG IN AREAS.
&&
.SHORT TERM /7 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE
EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS
FORECAST TO DRIVE INTO THE OHIO VALLEY. THE 13KM RAP FROM 0100 UTC
SHOWS LITTLE OR NO RAINFALL OVERNIGHT AND ORGANIZED RAIN WELL TO
OUR WEST IN MORNING HOURS. AN OPTIMISTIC ENSEMBLE OF TWO.
LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE
MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO
THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO
1800JKG-1 RANGE SECOND HALF OF THE DAY.
BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE
AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS.
OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS
WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z
TIMEFRAME.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN
LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION
POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE
THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT
CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS
SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE
MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL
PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF
UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE
CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL
PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE
ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY
FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY
NEXT WEEK AS RIDGE BUILDS OVER THE REGION.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
NOT A LOT OF CHANGE TO 03Z TAFS.
EARLIER DISCUSSION BELOW.
DID NOT CHANGE A LOT ON THE 00Z TAF PACKAGE FROM THE EARLIER
SET.
MAIN CONCERN IS CONVECTION ACROSS THE NW NEAR BFD. OTHER
WIDELY SCATTERED SHOWERS AND STORMS COULD MOVE EAST INTO
THE REST OF THE AREA OVERNIGHT.
MAIN ISSUE FOR AVN CONCERN OVERNIGHT WILL BE FOG AND LOW
CLOUDS WITH LGT/VRB WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS.
FOR THIS...WENT CLOSE TO EARLIER FCST. DID LOWER CIGS IN
SOME CASES. A BLEND OF GUIDANCE AND TIMING FROM LAST NIGHT.
FOR THU...EXPECT LESS SHOWER AND THUNDERSTORM ACTIVITY...AS
THE WIND SHIFT LINE AND DYNAMICS SHIFT EASTWARD.
OUTLOOK...
FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS
OF SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS.
SUN-MON...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...MARTIN/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1045 PM EDT WED AUG 20 2014
.SYNOPSIS...
AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST
ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF
HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD
ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
STILL SOME WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ABOUT THE
STATE TONIGHT CENTRAL AREAS. THERE IS ONE PERSISTENT AND SLOW TO
DIE ORGANIZED AREA OF CONVECTION OVER ELK AND NORTHERN CLEARFIELD
COUNTIES TONIGHT. IT IS MOVING SLOWLY TO THE SOUTH AND EAST. IT
HAS HELD TOGETHER ON RADAR FOR HOURS AND COLD CLOUD AREA IMPLIES
IT HAS SOME LIFE LEFT. LOW-LEVEL VELOCITY DATA IMPLIES IT HAS A
COLD POOL WHICH WILL LIKELY ALLOW IT TO PERSIST FOR A FEW MORE
HOURS. SO WE HAD TO KEEP RAIN AND POPS 80 TO 90 PERCENT UP THERE.
THE HRRR SHOWS THIS SYSTEM SPLITTING AND GOING ACROSS CENTRAL PA
THROUGH 0700 UTC. COULD SEE ISOLATED THUNDER AND RAIN AREAS IF THE
23Z HRRR IS CORRECT.
MOST OTHER AREAS UNAFFECTED BY THIS CONVECTION SHOULD SEE FOG
DEVELOP. PERHAPS PATCHY DENSE FOG IN AREAS.
&&
.SHORT TERM /7 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE
EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS
FORECAST TO DRIVE INTO THE OHIO VALLEY. THE 13KM RAP FROM 0100 UTC
SHOWS LITTLE OR NO RAINFALL OVERNIGHT AND ORGANIZED RAIN WELL TO
OUR WEST IN MORNING HOURS. AN OPTIMISTIC ENSEMBLE OF TWO.
LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE
MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO
THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO
1800JKG-1 RANGE SECOND HALF OF THE DAY.
BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE
AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS.
OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS
WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z
TIMEFRAME.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN
LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION
POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE
THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT
CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS
SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE
MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL
PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF
UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE
CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL
PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE
ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY
FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY
NEXT WEEK AS RIDGE BUILDS OVER THE REGION.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
DID NOT CHANGE A LOT ON THE 00Z TAF PACKAGE FROM THE EARLIER
SET.
MAIN CONCERN IS CONVECTION ACROSS THE NW NEAR BFD. OTHER
WIDELY SCATTERED SHOWERS AND STORMS COULD MOVE EAST INTO
THE REST OF THE AREA OVERNIGHT.
MAIN ISSUE FOR AVN CONCERN OVERNIGHT WILL BE FOG AND LOW
CLOUDS WITH LGT/VRB WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS.
FOR THIS...WENT CLOSE TO EARLIER FCST. DID LOWER CIGS IN
SOME CASES. A BLEND OF GUIDANCE AND TIMING FROM LAST NIGHT.
FOR THU...EXPECT LESS SHOWER AND THUNDERSTORM ACTIVITY...AS
THE WIND SHIFT LINE AND DYNAMICS SHIFT EASTWARD.
OUTLOOK...
FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS
OF SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS.
SUN-MON...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...MARTIN/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
823 PM EDT WED AUG 20 2014
.SYNOPSIS...
AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST
ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF
HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD
ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A FEW SCATTERED SHOWERS ABOUT TONIGHT. A WEAKENING LINE IN
EASTERN WARREN ENTERING MCKEAN COUNTY WHICH SHOULD SLOWLY FADE
AWAY NEXT FEW HOURS. THE SOUTHERN END OF THIS LINE WILL LIKELY
BRING THUNDER INTO ELK COUNTY BEFORE 830 PM.
ANOTHER CLUSTER OVER TIOGA COUNTY AND NORTHERN LYCOMING COUNTY
ARE THE MOST ORGANIZED.
CAMS SHOWS MOST OF THESE SYSTEMS WEAKENING AND FADING AWAY OVER
THE NEXT 1-2 HOURS SO KEPT LOWERING POPS AND MOVING SLOWLY
EASTWARD. CAMS ALSO SHOW A FEW AREAS OF CONVECTION RANDOMLY IN
CENTRAL PA OVERNIGHT. NOTHING OF NOTE.
SHOULD SEE FOG DEVELOP IN MANY AREAS TONIGHT. PERHAPS PATCHY
DENSE FOG IN AREAS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
OUR PW VALUES ARE LOW IN THE MORNING AND ARE FORECAST TO SLOWLY
RISE DURING THE DAY AND INTO THE EVENING. THE CAPE IN MOST MODELS
COMES UP INTO THE 600 TO 1800JKG-1 RANGE SECOND HALF OF THE DAY.
BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE
AFTERNOON. THE 3KM HRRR SEEMS TO THINK THAT THE CONVECTION OVER
IL/WI WILL ORGANIZE AND BE IN EAST/SE OHIO THURSDAY MORNING. THIS
IMPLIES THAT NO SHORT WAVES OR MCV ACTIVITY WILL BE AROUND IN THE
MORNING TO TRIGGER CONVECTION. THUS...THE SHOWERS TOMORROW SHOULD
BE LINKED TO THE RETURN FLOW AND INSOLATION. OPTIMISTIC IT COULD
BE A RAINFREE MORNING.
SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS WITH
RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z TIMEFRAME.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN
LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION
POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE
THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT
CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS
SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE
MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL
PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF
UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE
CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL
PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE
ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY
FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY
NEXT WEEK AS RIDGE BUILDS OVER THE REGION.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
DID NOT CHANGE A LOT ON THE 00Z TAF PACKAGE FROM THE EARLIER
SET.
MAIN CONCERN IS CONVECTION ACROSS THE NW NEAR BFD. OTHER
WIDELY SCATTERED SHOWERS AND STORMS COULD MOVE EAST INTO
THE REST OF THE AREA OVERNIGHT.
MAIN ISSUE FOR AVN CONCERN OVERNIGHT WILL BE FOG AND LOW
CLOUDS WITH LGT/VRB WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS.
FOR THIS...WENT CLOSE TO EARLIER FCST. DID LOWER CIGS IN
SOME CASES. A BLEND OF GUIDANCE AND TIMING FROM LAST NIGHT.
FOR THU...EXPECT LESS SHOWER AND THUNDERSTORM ACTIVITY...AS
THE WIND SHIFT LINE AND DYNAMICS SHIFT EASTWARD.
OUTLOOK...
FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS
OF SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS.
SUN-MON...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...MARTIN/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
742 PM EDT WED AUG 20 2014
.SYNOPSIS...
AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST
ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF
HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD
ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A FEW SCATTERED SHOWERS ABOUT TONIGHT. A WEAKENING LINE IN
EASTERN WARREN ENTERING MCKEAN COUNTY WHICH SHOULD SLOWLY FADE
AWAY NEXT FEW HOURS. THE SOUTHERN END OF THIS LINE WILL LIKELY
BRING THUNDER INTO ELK COUNTY BEFORE 830 PM.
ANOTHER CLUSTER OVER TIOGA COUNTY AND NORTHERN LYCOMING COUNTY
ARE THE MOST ORGANIZED.
CAMS SHOWS MOST OF THESE SYSTEMS WEAKENING AND FADING AWAY OVER
THE NEXT 1-2 HOURS SO KEPT LOWERING POPS AND MOVING SLOWLY
EASTWARD. CAMS ALSO SHOW A FEW AREAS OF CONVECTION RANDOMLY IN
CENTRAL PA OVERNIGHT. NOTHING OF NOTE.
SHOULD SEE FOG DEVELOP IN MANY AREAS TONIGHT. PERHAPS PATCHY
DENSE FOG IN AREAS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
OUR PW VALUES ARE LOW IN THE MORNING AND ARE FORECAST TO SLOWLY
RISE DURING THE DAY AND INTO THE EVENING. THE CAPE IN MOST MODELS
COMES UP INTO THE 600 TO 1800JKG-1 RANGE SECOND HALF OF THE DAY.
BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE
AFTERNOON. THE 3KM HRRR SEEMS TO THINK THAT THE CONVECTION OVER
IL/WI WILL ORGANIZE AND BE IN EAST/SE OHIO THURSDAY MORNING. THIS
IMPLIES THAT NO SHORT WAVES OR MCV ACTIVITY WILL BE AROUND IN THE
MORNING TO TRIGGER CONVECTION. THUS...THE SHOWERS TOMORROW SHOULD
BE LINKED TO THE RETURN FLOW AND INSOLATION. OPTIMISTIC IT COULD
BE A RAINFREE MORNING.
SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS WITH
RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z TIMEFRAME.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN
LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION
POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE
THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT
CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS
SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE
MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL
PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF
UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE
CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL
PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE
ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY
FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY
NEXT WEEK AS RIDGE BUILDS OVER THE REGION.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
STORM THAT PRODUCE INTENSE RAINFALL ACROSS THE NORTH SIDE OF
STATE COLLEGE AND THE OFFICE IS WELL EAST OF THE AREA. STILL
SOME WIDELY SCATTERED SHOWERS AND STORMS.
MAIN AREA OF CONCERN IS OVER NW PA WITH LINE OF STORMS.
DID NOT HIT THUNDER REAL HARD IN THE 21Z TAF UPDATE...EXCEPT
AT BFD.
AVN CONCERN TONIGHT WILL BE FOG AND LOW CLOUDS WITH LGT/VRB
WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS.
OUTLOOK...
FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS OF SHOWERS/TSTMS
AND BRIEF MVFR/IFR RESTRICTIONS.
SUN-MON...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...MARTIN/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
633 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A MASSIVE RIDGE WILL BUILD OVER EAST-CENTRAL CANADA FOR THE NEXT
WEEK. ANOTHER STRONG RIDGE WILL BUILD OVER THE SOUTHERN UNITED
STATES. SHORT-WAVES EMBEDDED IN THE WEAK FLOW MOVING UNDER THE
CANADIAN BLOCK WILL SLOW DOWN AND WEAKEN AS THEY MOVE THROUGH OUR
REGION. THIS WILL LEAD TO A POTENTIALLY PROLONGED PERIOD OF
UNSETTLED WEATHER. BUT IT SHOULD PROTECT US FROM THE LATE SEASON
HEAT BUILDING TO OUR SOUTH.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
A PLEASANT EVENING IS IN STORE FOR MOST OF THE REGION AS A NEARLY
N/S RIBBON OF RELATIVELY LOWER PWAT AIR /AROUND 1.0/ SLIDES EAST.
CLOUDS...AND ISOLATED TO SCATTERED SHOWERS WILL AFFECT MAINLY THE
LOWER SUSQ VALLEY THROUGH ABOUT 01Z WED.
PRECIP CHCS WILL BE ESSENTIALLY ZERO ACROSS MUCH OF CENTRAL AND
WESTERN PORTIONS OF THE CWA THROUGH 04-06Z...BEFORE A SHIELD OF
ANVIL CIRRUS...THEN PRECIP ENTERS OUR NW ZONES IN ASSOCIATION
WITH AN AREA TSRA MOVING ACROSS EXTREME SE MICH ATTM.
TEMPS WILL SLOWLY COOL OFF FROM THE LOWER TO MID 70S THIS
EVENING...BUT WILL LINGER AROUND 80F ACROSS THE FAR SE ZONES
THROUGH 00Z.
&&
.SHORT TERM /MIDNIGHT THROUGH 6 PM WEDNESDAY/...
THE HIGH RES WRF ARW AND HRRR SHOWS CONVECTION MOVING ACROSS LAKE
ERIE THIS EVENING AND INTO OUR FAR NW ZONES TWD 06Z /THOUGH THE
HRRR HAS TRENDED TWD A FEW-SEVERAL HOUR LATER ONSET OF THE
CONVECTION/. THIS AREA OF SHRA/TSRA SHOULD STEADILY
WEAKEN/FRAGMENT AS IT ENCOUNTERS LOWER PWATS AND A COOLER/MORE
STABLE LLVL ENVIRONMENT RESIDING OVER CENTRAL PENN.
POPS AFTER 06Z WILL INCREASE GRADUALLY TO ABOUT 30-40 PERCENT
BY DAYBREAK ACROSS THE WESTERN HALF OF THE CWA...BUT WILL REMIAN
AOB 15 PERCENT FURTHER EAST ACROSS THE ENTIRE SUSQ VALLEY.
PERVIOUS DISC BELOW...
A SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND
NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE WEAKENING RIDGE OVER EASTERN CANADA WILL ALLOW FOR DIVERGENT
FLOW AS THE UPPER LEVEL LOW SLOWLY MOVES EASTWARD. DAYTIME
HEATING...DECREASING PRESSURE...MOIST SOUTHEASTERLY SFC FLOW...AND
WEST TO NORTHWESTERLY FLOW ALOFT SHOULD ALLOW FOR ENOUGH
SHEAR...FOR CHANCE TO LIKELY POPS EARLY WEDNESDAY EVENING. CAPE
VALUES ARE LOW...WITH AN AVG OF 500-1K J/KG THROUGHOUT MOST OF
CENTRAL PA. SO SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE
EARLY WEDNESDAY EVENING. THESE WILL SLOWLY FADE AS THE EVENING
CONTINUES.
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY...WITH THE
850MB LOW MOVING THROUGH PA. COOL TEMPS ALOFT...COMBINED WITH
DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA AND TSRA BY THE
AFTERNOON. HAVE CONTINUED POPS IN THE LIKELY CATEGORY BASED ON 12Z
OPERATIONAL AND GEFS OUTPUT. DUE TO THE CHANGING POSITION AND
TIMING OF THE LOW...HAVE SLIGHTLY LOWERED POPS ALONG THE SOUTHERN
HALF OF THE CWA. THE SOUTHERLY LL JET AND PLUME OF HIGH PWATS WILL
HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE THREAT OF ANY
HVY RAINFALL. MODEL BLENDED QPF IS IN THE QUARTER TO HALF INCH
RANGE THURSDAY. BEFORE THE LOW PASSES...TEMPS COULD REACH UP TO
THE LOW 80S. AFTER THURSDAY/S NUMEROUS SHOWERS AND THE ADVECTION
OF COOLER TEMPS ALOFT...HIGH TEMPS SHOULD DROP BELOW NORMAL FOR
AUGUST...WITH MAXES MAINLY IN THE 70S THROUGH THE END OF THE WORK
WEEK INTO THE WEEKEND.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARM UP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
BULK OF SHOWERS AND STORMS OVER WITH...JUST A FEW ACROSS THE
FAR SOUTH. 21Z TAFS ADJUSTED FOR THIS.
EARLIER DISCUSSION BELOW.
THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.
SO MORE AREAS OF MVFR AND IFR.
WEDNESDAY WILL SEE RAIN AND SHOWERS LIKELY IN WESTERN PA BY
MID TO LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS
MVFR LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS.
OUTLOOK...
THU-SAT...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT CHC OF
MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED RESTRICTIONS.
SUN...MAINLY VFR. STILL CHANCE OF SHRA IN THE MORNING.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT/GRUMM
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT/GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...GRUMM/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
523 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A MASSIVE RIDGE WILL BUILD OVER EAST-CENTRAL CANADA FOR THE NEXT
WEEK. ANOTHER STRONG RIDGE WILL BUILD OVER THE SOUTHERN UNITED
STATES. SHORT-WAVES IN THE WEAK FLOW MOVING UNDER THE CANADIAN
BLOCK WILL SLOW DOWN AND WEAKEN AS THEY MOVE THROUGH OUR REGION.
THIS WILL LEAD TO A POTENTIALLY PROLONGED PERIOD OF UNSETTLED
WEATHER. BUT IT SHOULD PROTECT US FROM THE LATE SEASON HEAT
BUILDING TO OUR SOUTH.
&&
.NEAR TERM /UNTIL 9 PM THIS EVENING/...
A WEAKLY ORGANIZED BROKEN LINE OF SHOWERS AND ISOLATED
THUNDERSTORMS IS TRYING TO WORK ITS AWAY ACROSS OUR WEST-CENTRAL
COUNTIES FROM CENTRE COUNTY DOWN TO THE MARYLAND BORDER. BUMPED
UP POPS AND ADDED TEXTURE TO THE GRIDS WITH 3KM HRRR AND 4KM NAM
ESTIMATED POPS/QPF.
RADAR SHOWS VERY LIGHT RAIN. LOCAL GAGES SHOW ABOUT 0.10 IN
WESTERN AREAS OF STATE COLLEGE. BUT SOME STREAKS ON RADAR OF 0.1
TO 0.4 INCHES. IN SOMERSET COUNTY...STRONGER CELLS SHOWS CLOSE TO
AN INCH OF ESTIMATED RAINFALL. RADAR AND HRRR IMPLY BEST CHANCE
RAIN WILL BE FROM CAMBRIA AND SOMERSET COUNTIES EASTWARD TO
HUNTINGTON AND FRANKLIN COUNTY AS THE STRONGEST ELEMENTS HEAD
SLOWLY EAST.
THE 3KM AND 4KM MODELS IMPLY MOST OF THIS CONVECTION DIES OFF A
FEW HOURS EITHER SIDE 6 PM.
&&
.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. MOST AREAS RAIN FREE IN HRRR AFTER 0000 UTC TONIGHT
THROUGH 0600 UTC.
BUT THE HRRR DOES SHOW OVERNIGHT CONVECTION IN THE MIDWEST MOVING
INTO WESTERN PA AFTER 0600 UTC. CHANCE RAIN WILL CLEARER INCREASE
BEFORE SUNRISE IN WESTERN AREAS.
THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND
NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE WEAKENING RIDGE OVER EASTERN CANADA WILL ALLOW FOR DIVERGENT
FLOW AS THE UPPER LEVEL LOW SLOWLY MOVES EASTWARD. DAYTIME
HEATING...DECREASING PRESSURE...MOIST SOUTHEASTERLY SFC FLOW...AND
WEST TO NORTHWESTERLY FLOW ALOFT SHOULD ALLOW FOR ENOUGH
SHEAR...FOR CHANCE TO LIKELY POPS EARLY WEDNESDAY EVENING. CAPE
VALUES ARE LOW...WITH AN AVG OF 500-1K J/KG THROUGHOUT MOST OF
CENTRAL PA. SO SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE
EARLY WEDNESDAY EVENING. THESE WILL SLOWLY FADE AS THE EVENING
CONTINUES.
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY...WITH THE
850MB LOW MOVING THROUGH PA. COOL TEMPS ALOFT...COMBINED WITH
DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA AND TSRA BY THE
AFTERNOON. HAVE CONTINUED POPS IN THE LIKELY CATEGORY BASED ON 12Z
OPERATIONAL AND GEFS OUTPUT. DUE TO THE CHANGING POSITION AND
TIMING OF THE LOW...HAVE SLIGHTLY LOWERED POPS ALONG THE SOUTHERN
HALF OF THE CWA. THE SOUTHERLY LL JET AND PLUME OF HIGH PWATS WILL
HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE THREAT OF ANY
HVY RAINFALL. MODEL BLENDED QPF IS IN THE QUARTER TO HALF INCH
RANGE THURSDAY. BEFORE THE LOW PASSES...TEMPS COULD REACH UP TO
THE LOW 80S. AFTER THURSDAY/S NUMEROUS SHOWERS AND THE ADVECTION
OF COOLER TEMPS ALOFT...HIGH TEMPS SHOULD DROP BELOW NORMAL FOR
AUGUST...WITH MAXES MAINLY IN THE 70S THROUGH THE END OF THE WORK
WEEK INTO THE WEEKEND.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARM UP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
BULK OF SHOWERS AND STORMS OVER WITH...JUST A FEW ACROSS THE
FAR SOUTH. 21Z TAFS ADJUSTED FOR THIS.
EARLIER DISCUSSION BELOW.
THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.
SO MORE AREAS OF MVFR AND IFR.
WEDNESDAY WILL SEE RAIN AND SHOWERS LIKELY IN WESTERN PA BY
MID TO LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS
MVFR LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS.
OUTLOOK...
THU-SAT...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT CHC OF
MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED RESTRICTIONS.
SUN...MAINLY VFR. STILL CHANCE OF SHRA IN THE MORNING.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...GRUMM/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
351 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A MASSIVE RIDGE WILL BUILD OVER EAST-CENTRAL CANADA FOR THE NEXT
WEEK. ANOTHER STRONG RIDGE WILL BUILD OVER THE SOUTHERN UNITED
STATES. SHORT-WAVES IN THE WEAK FLOW MOVING UNDER THE CANADIAN
BLOCK WILL SLOW DOWN AND WEAKEN AS THEY MOVE THROUGH OUR REGION.
THIS WILL LEAD TO A POTENTIALLY PROLONGED PERIOD OF UNSETTLED
WEATHER. BUT IT SHOULD PROTECT US FROM THE LATE SEASON HEAT
BUILDING TO OUR SOUTH.
&&
.NEAR TERM /UNTIL 9 PM THIS EVENING/...
A WEAKLY ORGANIZED BROKEN LINE OF SHOWERS AND ISOLATED
THUNDERSTORMS IS TRYING TO WORK ITS AWAY ACROSS OUR WEST-CENTRAL
COUNTIES FROM CENTRE COUNTY DOWN TO THE MARYLAND BORDER. BUMPED UP
POPS AND ADDED TEXTURE TO THE GRIDS WITH 3KM HRRR AND 4KM NAM
ESTIMATED POPS/QPF.
RADAR SHOWS VERY LIGHT RAIN. LOCAL GAGES SHOW ABOUT 0.10 IN
WESTERN AREAS OF STATE COLLEGE. BUT SOME STREAKS ON RADAR OF 0.1
TO 0.4 INCHES. IN SOMERSET COUNTY...STRONGER CELLS SHOWS CLOSE TO
AN INCH OF ESTIMATED RAINFALL. RADAR AND HRRR IMPLY BEST CHANCE
RAIN WILL BE FROM CAMBRIA AND SOMERSET COUNTIES EASTWARD TO
HUNTINGTON AND FRANKLIN COUNTY AS THE STRONGEST ELEMENTS HEAD
SLOWLY EAST.
THE 3KM AND 4KM MODELS IMPLY MOST OF THIS CONVECTION DIES OFF A
FEW HOURS EITHER SIDE 6 PM.
&&
.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. MOST AREAS RAIN FREE IN HRRR AFTER 0000 UTC TONIGHT
THROUGH 0600 UTC.
BUT THE HRRR DOES SHOW OVERNIGHT CONVECTION IN THE MIDWEST MOVING
INTO WESTERN PA AFTER 0600 UTC. CHANCE RAIN WILL CLEARER INCREASE
BEFORE SUNRISE IN WESTERN AREAS.
THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND
NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE WEAKENING RIDGE OVER EASTERN CANADA WILL ALLOW FOR DIVERGENT
FLOW AS THE UPPER LEVEL LOW SLOWLY MOVES EASTWARD. DAYTIME
HEATING...DECREASING PRESSURE...MOIST SOUTHEASTERLY SFC FLOW...AND
WEST TO NORTHWESTERLY FLOW ALOFT SHOULD ALLOW FOR ENOUGH
SHEAR...FOR CHANCE TO LIKELY POPS EARLY WEDNESDAY EVENING. CAPE
VALUES ARE LOW...WITH AN AVG OF 500-1K J/KG THROUGHOUT MOST OF
CENTRAL PA. SO SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE
EARLY WEDNESDAY EVENING. THESE WILL SLOWLY FADE AS THE EVENING
CONTINUES.
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY...WITH THE
850MB LOW MOVING THROUGH PA. COOL TEMPS ALOFT...COMBINED WITH
DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA AND TSRA BY THE
AFTERNOON. HAVE CONTINUED POPS IN THE LIKELY CATEGORY BASED ON 12Z
OPERATIONAL AND GEFS OUTPUT. DUE TO THE CHANGING POSITION AND
TIMING OF THE LOW...HAVE SLIGHTLY LOWERED POPS ALONG THE SOUTHERN
HALF OF THE CWA. THE SOUTHERLY LL JET AND PLUME OF HIGH PWATS WILL
HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE THREAT OF ANY
HVY RAINFALL. MODEL BLENDED QPF IS IN THE QUARTER TO HALF INCH
RANGE THURSDAY. BEFORE THE LOW PASSES...TEMPS COULD REACH UP TO
THE LOW 80S. AFTER THURSDAY/S NUMEROUS SHOWERS AND THE ADVECTION
OF COOLER TEMPS ALOFT...HIGH TEMPS SHOULD DROP BELOW NORMAL FOR
AUGUST...WITH MAXES MAINLY IN THE 70S THROUGH THE END OF THE WORK
WEEK INTO THE WEEKEND.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARM UP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
RADAR SHOWS SOME ORGANIZED SHOWERS AND THUNDERSTORMS FROM NEAR
KFIG SOUTH TO THE MARYLAND BORDER. THESE SHOWERS AND STORMS WILL
SLOWLY MOVE EASTWARD THIS AFTERNOON. AREAS OF MVFR AND LOCALLY IFR
ARE POSSIBLE ALONG THE LINE AND WITHIN THE SHOWERS AND
THUNDERSTORMS.
MODELS ALL SUGGEST POPCORN SHOWERS POSSIBLE OVER MOST OF CENTRAL
PA AND THE MORE ORGANIZED ACTIVITY OVER THE SOUTHERN HALF OF THE
STATE THROUGH THIS EVENING.
THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.SO
MORE AREAS OF MVFR AND IFR.
WEDNESDAY WILL SEE RAIN AND SHOWERS LIKELY IN WESTERN PA BY MID-
LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS MVFR
LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS.
OUTLOOK...
TUE...MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED...MORNING FOG/LOW CLOUDS SHRA/TSRA LIKELY WEST CHANCE EAST.
THU-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT
DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...CERU/FITZGERALD
AVIATION...GRUMM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
206 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A MASSIVE RIDGE WILL BUILD OVER EAST-CENTRAL CANADA FOR THE NEXT
WEEK. ANOTHER STRONG RIDGE WILL BUILD OVER THE SOUTHERN UNITED
STATES. SHORT-WAVES IN THE WEAK FLOW MOVING UNDER THE CANADIAN
BLOCK WILL SLOW DOWN AND WEAKEN AS THEY MOVE THROUGH OUR REGION.
THIS WILL LEAD TO A POTENTIALLY PROLONGED PERIOD OF UNSETTLED
WEATHER. BUT IT SHOULD PROTECT US FROM THE LATE SEASON HEAT
BUILDING TO OUR SOUTH.
&&
.NEAR TERM /UNTIL 9 PM THIS EVENING/...
A WEAKLY ORGANIZED BROKEN LINE OF SHOWERS AND ISOLATED
THUNDERSTORMS IS TRYING TO WORK ITS AWAY ACROSS OUR WEST-CENTRAL
COUNTIES FROM CENTRE COUNTY DOWN TO THE MARYLAND BORDER. BUMPED UP
POPS AND ADDED TEXTURE TO THE GRIDS WITH 3KM HRRR AND 4KM NAM
ESTIMATED POPS/QPF.
RADAR SHOWS VERY LIGHT RAIN. LOCAL GAGES SHOW ABOUT 0.10 IN
WESTERN AREAS OF STATE COLLEGE. BUT SOME STREAKS ON RADAR OF 0.1
TO 0.4 INCHES. IN SOMERSET COUNTY...STRONGER CELLS SHOWS CLOSE TO
AN INCH OF ESTIMATED RAINFALL. RADAR AND HRRR IMPLY BEST CHANCE
RAIN WILL BE FROM CAMBRIA AND SOMERSET COUNTIES EASTWARD TO
HUNTINGTON AND FRANKLIN COUNTY AS THE STRONGEST ELEMENTS HEAD
SLOWLY EAST.
THE 3KM AND 4KM MODELS IMPLY MOST OF THIS CONVECTION DIES OFF A
FEW HOURS EITHER SIDE 6 PM.
&&
.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. MOST AREAS RAINFREE IN HRRR AFTER 0000 UTC TONIGHT
THROUGH 0600 UTC.
BUT THE HRRR DOES SHOW OVERNIGHT CONVECTION IN THE MIDWEST MOVING
INTO WESTERN PA AFTER 0600 UTC. CHANCE RAIN WILL CLEARER INCREASE
BEFORE SUNRISE IN WESTERN AREAS.
THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND
NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS
ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA
AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON
00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH
PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE
THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO
HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS
ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH
MAXES MAINLY IN THE 70S.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
RADAR SHOWS SOME ORGANIZED SHOWERS AND THUNDERSTORMS FROM NEAR
KFIG SOUTH TO THE MARYLAND BORDER. THESE SHOWERS AND STORMS WILL
SLOWLY MOVE EASTWARD THIS AFTERNOON. AREAS OF MVFR AND LOCALLY IFR
ARE POSSIBLE ALONG THE LINE AND WITHIN THE SHOWERS AND
THUNDERSTORMS.
MODELS ALL SUGGEST POPCORN SHOWERS POSSIBLE OVER MOST OF CENTRAL
PA AND THE MORE ORGANIZED ACTIVITY OVER THE SOUTHERN HALF OF THE
STATE THROUGH THIS EVENING.
THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.SO
MORE AREAS OF MVFR AND IFR.
WEDNESDAY WILL SEE RAIN AND SHOWERS LIKELY IN WESTERN PA BY MID-
LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS MVFR
LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS.
OUTLOOK...
TUE...MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED...MORNING FOG/LOW CLOUDS SHRA/TSRA LIKELY WEST CHANCE EAST.
THU-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT
DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD
AVIATION...GRUMM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
201 PM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER LOW OVR THE W GRT LKS WILL DRIFT SLOWLY SE ACROSS UPSTATE
NY AND NEW ENG BY LATE THIS WEEK. A LARGE SFC HIGH OVR THE CANADIAN
MARITIMES WILL RIDGE SOUTHWARD INTO PA DURING THE UPCOMING WEEKEND
AND EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 9 PM THIS EVENING/...
A WEAKLY ORGANIZED BROKEN LINE OF SHOWERS AND ISOLATED
THUNDERSTORMS IS TRYING TO WORK ITS AWAY ACROSS OUR WEST-CENTRAL
COUNTIES FROM CENTRE COUNTY DOWN TO THE MARYLAND BORDER. BUMPED UP
POPS AND ADDED TEXTURE TO THE GRIDS WITH 3KM HRRR AND 4KM NAM
ESTIMATED POPS/QPF.
RADAR SHOWS VERY LIGHT RAIN. LOCAL GAGES SHOW ABOUT 0.10 IN
WESTERN AREAS OF STATE COLLEGE. BUT SOME STREAKS ON RADAR OF 0.1
TO 0.4 INCHES. IN SOMERSET COUNTY...STRONGER CELLS SHOWS CLOSE TO
AN INCH OF ESTIMATED RAINFALL. RADAR AND HRRR IMPLY BEST CHANCE
RAIN WILL BE FROM CAMBRIA AND SOMERSET COUNTIES EASTWARD TO
HUNTINGTON AND FRANKLIN COUNTY AS THE STRONGEST ELEMENTS HEAD
SLOWLY EAST.
THE 3KM AND 4KM MODELS IMPLY MOST OF THIS CONVECTION DIES OFF A
FEW HOURS EITHER SIDE 6 PM.
&&
.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. MOST AREAS RAINFREE IN HRRR AFTER 0000 UTC TONIGHT
THROUGH 0600 UTC.
BUT THE HRRR DOES SHOW OVERNIGHT CONVECTION IN THE MIDWEST MOVING
INTO WESTERN PA AFTER 0600 UTC. CHANCE RAIN WILL CLEARER INCREASE
BEFORE SUNRISE IN WESTERN AREAS.
THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND
NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS
ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA
AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON
00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH
PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE
THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO
HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS
ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH
MAXES MAINLY IN THE 70S.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
RADAR SHOWS SOME ORGANIZED SHOWERS AND THUNDERSTORMS FROM NEAR
KFIG SOUTH TO THE MARYLAND BORDER. THESE SHOWERS AND STORMS WILL
SLOWLY MOVE EASTWARD THIS AFTERNOON. AREAS OF MVFR AND LOCALLY IFR
ARE POSSIBLE ALONG THE LINE AND WITHIN THE SHOWERS AND
THUNDERSTORMS.
MODELS ALL SUGGEST POPCORN SHOWERS POSSIBLE OVER MOST OF CENTRAL
PA AND THE MORE ORGANIZED ACTIVITY OVER THE SOUTHERN HALF OF THE
STATE THROUGH THIS EVENING.
THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.SO
MORE AREAS OF MVFR AND IFR.
WEDNESDAY WILL SEE RAIN AND SHOWERS LIKELY IN WESTERN PA BY MID-
LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS MVFR
LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS.
OUTLOOK...
TUE...MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED...MORNING FOG/LOW CLOUDS SHRA/TSRA LIKELY WEST CHANCE EAST.
THU-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT
DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD
AVIATION...GRUMM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
128 PM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER LOW OVR THE W GRT LKS WILL DRIFT SLOWLY SE ACROSS UPSTATE
NY AND NEW ENG BY LATE THIS WEEK. A LARGE SFC HIGH OVR THE CANADIAN
MARITIMES WILL RIDGE SOUTHWARD INTO PA DURING THE UPCOMING WEEKEND
AND EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
LOW CLOUDS SLOWLY LIFTING AND MOVING TO THE EAST. RADAR HAS
DETECTED SHOWERS WHICH DEVELOPED ON THE WESTERN EDGE OF THIS CLOUD
SHIELD AND HAS MOVED INTO CLEARFIELD COUNTY. SOME HINTS OF WEAK
CONVECTION IN THE HRRR AND 4KM NAM. USED THESE MODELS TO ADD
TEXTURE TO THE FORECAST SHOWING SHOWERS AND ISOLATED THUNDERSTORMS
DRIFTING ACROSS PENNSYLVANIA THIS MORNING AND AFTERNOON.
TRIED TO KEEP POPS IN CHANCE RANGE AS THERE IS LIMITED
ORGANIZATION TO THE CONVECTION. HOWEVER...3KM HRRR UPDATES FROM
NCEPS EXPERIMENTAL HRRR SHOW DIFFERENT AREAS OF SHOWERS IN CENTRAL
PA ALL AFTERNOON AND NOW IMPLY MORE ORGANIZED THUNDERSTORMS IN
S-SE COUNTIES IN LATE AFTERNOON EVENING. SEE HOW THIS EVOLVES.
SKIES SHOULD SLOWLY GET BETTER DURING DAY CENTRAL AREAS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF
AND NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS
ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA
AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON
00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH
PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE
THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO
HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS
ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH
MAXES MAINLY IN THE 70S.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
RADAR SHOWS SOME ORGANIZED SHOWERS AND THUNDERSTORMS FROM NEAR
KFIG SOUTH TO THE MARYLAND BORDER. THESE SHOWERS AND STORMS WILL
SLOWLY MOVE EASTWARD THIS AFTERNOON. AREAS OF MVFR AND LOCALLY IFR
ARE POSSIBLE ALONG THE LINE AND WITHIN THE SHOWERS AND
THUNDERSTORMS.
MODELS ALL SUGGEST POPCORN SHOWERS POSSIBLE OVER MOST OF CENTRAL
PA AND THE MORE ORGANIZED ACTIVITY OVER THE SOUTHERN HALF OF THE
STATE THROUGH THIS EVENING.
THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.SO
MORE AREAS OF MVFR AND IFR.
WEDNESDAY WILL SEE RAIN AND SHOWERS LIKELY IN WESTERN PA BY MID-
LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS MVFR
LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS.
OUTLOOK...
TUE...MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED...MORNING FOG/LOW CLOUDS SHRA/TSRA LIKELY WEST CHANCE EAST.
THU-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT
DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD
AVIATION...GRUMM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1128 AM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER LOW OVR THE W GRT LKS WILL DRIFT SLOWLY SE ACROSS UPSTATE
NY AND NEW ENG BY LATE THIS WEEK. A LARGE SFC HIGH OVR THE CANADIAN
MARITIMES WILL RIDGE SOUTHWARD INTO PA DURING THE UPCOMING WEEKEND
AND EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
LOW CLOUDS SLOWLY LIFTING AND MOVING TO THE EAST. RADAR HAS
DETECTED SHOWERS WHICH DEVELOPED ON THE WESTERN EDGE OF THIS CLOUD
SHIELD AND HAS MOVED INTO CLEARFIELD COUNTY. SOME HINTS OF WEAK
CONVECTION IN THE HRRR AND 4KM NAM. USED THESE MODELS TO ADD
TEXTURE TO THE FORECAST SHOWING SHOWERS AND ISOLATED THUNDERSTORMS
DRIFTING ACROSS PENNSYLVANIA THIS MORNING AND AFTERNOON.
TRIED TO KEEP POPS IN CHANCE RANGE AS THERE IS LIMITED
ORGANIZATION TO THE CONVECTION. HOWEVER...3KM HRRR UPDATES FROM
NCEPS EXPERIMENTAL HRRR SHOW DIFFERENT AREAS OF SHOWERS IN CENTRAL
PA ALL AFTERNOON AND NOW IMPLY MORE ORGANIZED THUNDERSTORMS IN
S-SE COUNTIES IN LATE AFTERNOON EVENING. SEE HOW THIS EVOLVES.
SKIES SHOULD SLOWLY GET BETTER DURING DAY CENTRAL AREAS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF
AND NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS
ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA
AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON
00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH
PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE
THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO
HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS
ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH
MAXES MAINLY IN THE 70S.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
STILL LINGERING AREAS OF MVFR AND ISOLATED IFR AS THE LOW CLOUDS
AND PATCHY FOG FROM EARLY THIS MORNING AND LIFT AND SLOWLY DRIFT
TO THE EAST.
A LINE OF SHOWERS WITH ISOLATED THUNDER HAS DEVELOPED OVER THE
CENTRAL MOUNTAINS. THIS COULD BRING SHOWERS FROM KFIG SOUTH TO
KAOO AND KJST AND EVENTUALLY THE KUNV AREA. ADDED SHOWERS VICINITY
TO THESE SITES. THIS COULD MOVE FARTHER EAST.
MODELS SHOW ISOLATED TO SCATTERED SHOWERS RANDOMLY PLACED ABOUT
CENTRAL AND SOUTHERN PA OVER NEXT 12 HOURS.
THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.
RAIN AND SHOWERS LIKELY IN WESTERN PA BY MID-LATE MORNING SLOWLY
SPREADING EAST. VFR IN EAST BUT AREAS MVFR LIKELY IN AM FOG AND
THEN SHOWERS IN WESTERN AREAS.
OUTLOOK...
TUE...MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED...MORNING FOG/LOW CLOUDS SHRA/TSRA LIKELY WEST CHANCE EAST.
THU-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT
DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD
AVIATION...GRUMM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1114 AM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER LOW OVR THE W GRT LKS WILL DRIFT SLOWLY SE ACROSS UPSTATE
NY AND NEW ENG BY LATE THIS WEEK. A LARGE SFC HIGH OVR THE CANADIAN
MARITIMES WILL RIDGE SOUTHWARD INTO PA DURING THE UPCOMING WEEKEND
AND EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
LOW CLOUDS SLOWLY LIFTING AND MOVING TO THE EAST. RADAR HAS
DETECTED SHOWERS WHICH DEVELOPED ON THE WESTERN EDGE OF THIS CLOUD
SHIELD AND HAS MOVED INTO CLEARFIELD COUNTY. SOME HINTS OF WEAK
CONVECTION IN THE HRRR AND 4KM NAM. USED THESE MODELS TO ADD
TEXTURE TO THE FORECAST SHOWING SHOWERS AND ISOLATED THUNDERSTORMS
DRIFTING ACROSS PENNSYLVANIA THIS MORNING AND AFTERNOON.
TRIED TO KEEP POPS IN CHANCE RANGE AS THERE IS LIMITED
ORGANIZATION TO THE CONVECTION. HOWEVER...3KM HRRR UPDATES FROM
NCEPS EXPERIMENTAL HRRR SHOW DIFFERENT AREAS OF SHOWERS IN CENTRAL
PA ALL AFTERNOON AND NOW IMPLY MORE ORGANIZED THUNDERSTORMS IN
S-SE COUNTIES IN LATE AFTERNOON EVENING. SEE HOW THIS EVOLVES.
SKIES SHOULD SLOWLY GET BETTER DURING DAY CENTRAL AREAS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF
AND NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS
ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA
AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON
00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH
PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE
THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO
HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS
ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH
MAXES MAINLY IN THE 70S.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL GIVE WAY TO FOG AND LOWERING VSBYS OVERNIGHT
UNDER CLEAR SKIES AND LIGHT WINDS. EXPECT WIDESPREAD MVFR TO IFR
VSBYS AND CIGS TO DEVELOP OVERNIGHT AT MOST CENTRAL AND NORTHERN
AIRFIELDS. HOWEVER...HAVE NOT INCLUDED FOG IN THE LOWER
SUSQUEHANNA TAFS OF KMDT AND KLNS...AS CONFIDENCE OF FORMATION IS
LOWER. IF FOG DOES DEVELOP...LIKELY TO BE IN THE MVFR RANGE AT
THESE LOCATIONS.
CURRENT TIMING OF FOG IS FOR DEVELOPMENT AROUND 07Z IN MOST
LOCATIONS...WITH THE DENSEST FOG BETWEEN 09Z AND 12Z.
AFTER MORNING FOG...EXPECT GENERALLY VFR CONDITIONS. THERE IS A
THREAT FOR SHRA/TSRA...MOST LIKELY IN THE SOUTHWEST AND LEAST
LIKELY IN THE NORTHEAST.
A VERY SLOW APPROACHING UPPER LOW WILL SLOWLY INCREASE CHANCES FOR
DAILY SHOWERS AND POTENTIAL AFTERNOON TSRA FOR THE BALANCE OF THE
WEEK. CURRENTLY...LATER WEDNESDAY AND THURSDAY LOOK LIKE THE
HIGHEST LIKELIHOOD OF PRECIPITATION...WITH SURFACE FRONT CROSSING
THE REGION.
OUTLOOK...
TUE...MORNING FOG...THEN MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS.
SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...FITZGERALD
AVIATION...GRUMM/GARTNER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
756 AM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER LOW OVR THE W GRT LKS WILL DRIFT SLOWLY SE ACROSS UPSTATE
NY AND NEW ENG BY LATE THIS WEEK. A LARGE SFC HIGH OVR THE CANADIAN
MARITIMES WILL RIDGE SOUTHWARD INTO PA DURING THE UPCOMING WEEKEND
AND EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
WEAK UPPER-LEVEL LOWS ARE STRUGGLING TO MAKE IT UNDER THE
RETROGRADING UPPER LEVEL RIDGE. MODELS FOR DAYS NOW HAVE BEEN
WETTER THAN REALITY. THE SREF AND GEFS ARE MORE ROBUST WITH SHOWER
POTENTIAL TODAY THAN THE HIGH RESOLUTION CONVECTIVE FOLLOWING
MODELS.
LATEST 4KM NAM AND 3KM HRRR IMPLY SOME VERY ISOLATED CONVECTION
ABOUT CENTRAL PA THIS AFTERNOON AND EARLY EVENING. NOTHING
ORGANIZED OR SIGNIFICANT. SORT OF A QUANDARY HOW TO EFFECTIVELY
USE THESE DATA VERSE THE LARGER SCALE MODELS WHERE CONVECTION IS
GENERATED BY RELEASING INSTABILITY IN THE CONVECTIVE
PARAMETERIZATION SCHEMES (CPS). BIASED POPS LOWER TOWARD
CONVECTIVE ALLOWING MODELS THAT DO NOT USE CPS.
MODELS IMPLY PARTLY TO MOSTLY CLOUDY TODAY. FIRST BATCH OF LOW
CLOUDS IN SW PA WILL SHRINK AS IT ADVECTS ACROSS THE STATE.
TEMPERATURE WISE CLOSE TO NORMAL.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
ANY SHOWER ACTIVITY THAT DEVELOPS SHOULD FADE FAST AROUND SUNSET.
BUILDING 5940M RIDGE IN SOUTHERN US AND BLOCKING RIDGE TO OUR
NORTH. WE ARE STUCK IN THE SQUEEZE PLAY BETWEEN THEM. AN ANEMIC
FRONTAL SYSTEM TRIES TO PUSH THROUGH THE REGION. SREF LARGER SCALE
MODELS SHOW SOME SURGE OF SLIGHTLY ABOVE NORMAL PW AND SOME CAPE
INTO WESTERN PA. POPS SHOULD DROP OFF TO EAST AS THIS SYSTEM WILL
WEAKEN AS IT MOVES BENEATH THE BLOCK. BEST CHANCE...AS MENTIONED
BELOW FOR SEVERAL TENTHS WOULD BE IN WEST VERY LIGHT RAINFALL IN
EASTERN AREAS.
PREVIOUS: PASSAGE OF SHORTWAVE AND COOLING OF BLYR SHOULD CAUSE
ANY EARLY EVENING SHOWERS TO DIMINISH SHORTLY AFTER SUNSET.
HOWEVER...APPROACH OF UPPER LOW AND ASSOC LL JET/PLUME OF
ANOMALOUS PWATS COULD SPREAD SHRA/TSRA INTO THE NW MTNS TOWARD
DAWN WED.
HAVE RAISED POPS MARKEDLY ACROSS THE AREA WED...AS MDLS NOW IN
AGREEMENT WITH TIMING OF LL JET/PLUME OF ANOMALOUS PWATS. BLEND OF
OPER AND ENSEMBLE GUIDANCE SUGGESTS MOST LIKELY RAINFALL WED WILL
RANGE FROM LESS THAN 0.10 INCHES SE OF HARRISBURG...TO ARND A HALF
INCH ACROSS WARREN CO. HOWEVER...MUCH HIGHER LOCALIZED AMTS ARE
LIKELY ACROSS THE W MTNS...WHERE ENVIRONMENT OF MODERATE INSTABILITY
AND HIGH PWATS WILL MAKE LOCALLY HVY TSRA POSSIBLE. CONVECTION-
ALLOWING MDLS SUPPORT THIS SCENARIO WITH SPOT AMTS OF ARND 2
INCHES ON WED ACROSS THE W MTNS. A MORE STABLE MARITIME AIR MASS
OVR EASTERN PA WILL MAKE TSRA UNLIKELY THERE.
GEFS 925 TEMPS ARE SUPPORTIVE OF HIGH TEMPS WED FROM THE M70S OVR
THE ALLEGHENY PLATEAU...TO THE L80S OVR THE SUSQ VALLEY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS
ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA
AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON
00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH
PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE
THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO
HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS
ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH
MAXES MAINLY IN THE 70S.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL GIVE WAY TO FOG AND LOWERING VSBYS OVERNIGHT
UNDER CLEAR SKIES AND LIGHT WINDS. EXPECT WIDESPREAD MVFR TO IFR
VSBYS AND CIGS TO DEVELOP OVERNIGHT AT MOST CENTRAL AND NORTHERN
AIRFIELDS. HOWEVER...HAVE NOT INCLUDED FOG IN THE LOWER
SUSQUEHANNA TAFS OF KMDT AND KLNS...AS CONFIDENCE OF FORMATION IS
LOWER. IF FOG DOES DEVELOP...LIKELY TO BE IN THE MVFR RANGE AT
THESE LOCATIONS.
CURRENT TIMING OF FOG IS FOR DEVELOPMENT AROUND 07Z IN MOST
LOCATIONS...WITH THE DENSEST FOG BETWEEN 09Z AND 12Z.
AFTER MORNING FOG...EXPECT GENERALLY VFR CONDITIONS. THERE IS A
THREAT FOR SHRA/TSRA...MOST LIKELY IN THE SOUTHWEST AND LEAST
LIKELY IN THE NORTHEAST.
A VERY SLOW APPROACHING UPPER LOW WILL SLOWLY INCREASE CHANCES FOR
DAILY SHOWERS AND POTENTIAL AFTERNOON TSRA FOR THE BALANCE OF THE
WEEK. CURRENTLY...LATER WEDNESDAY AND THURSDAY LOOK LIKE THE
HIGHEST LIKELIHOOD OF PRECIPITATION...WITH SURFACE FRONT CROSSING
THE REGION.
OUTLOOK...
TUE...MORNING FOG...THEN MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS.
SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...GRUMM
SHORT TERM...GRUMM/FITZGERALD
LONG TERM...FITZGERALD
AVIATION...JUNG/GARTNER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
747 AM EDT TUE AUG 19 2014
.SYNOPSIS...
AN UPPER LOW OVR THE W GRT LKS WILL DRIFT SLOWLY SE ACROSS UPSTATE
NY AND NEW ENG BY LATE THIS WEEK. A LARGE SFC HIGH OVR THE CANADIAN
MARITIMES WILL RIDGE SOUTHWARD INTO PA DURING THE UPCOMING WEEKEND
AND EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
WEAK UPPER-LEVEL LOWS ARE STRUGGLING TO MAKE IT UNDER THE
RETROGRADING UPPER LEVEL RIDGE. MODELS FOR DAYS NOW HAVE BEEN
WETTER THAN REALITY. THE SREF AND GEFS ARE MORE ROBUST WITH SHOWER
POTENTIAL TODAY THAN THE HIGH RESOLUTION CONVECTIVE FOLLOWING
MODELS.
LATEST 4KM NAM AND 3KM HRRR IMPLY SOME VERY ISOLATED CONVECTION
ABOUT CENTRAL PA THIS AFTERNOON AND EARLY EVENING. NOTHING
ORGANIZED OR SIGNIFICANT. SORT OF A QUANDARY HOW TO EFFECTIVELY
USE THESE DATA VERSE THE LARGER SCALE MODELS WHERE CONVECTION IS
GENERATED BY RELEASING INSTABILITY IN THE CONVECTIVE
PARAMETERIZATION SCHEMES (CPS). BIASED POPS LOWER TOWARD
CONVECTIVE ALLOWING MODELS THAT DO NOT USE CPS.
MODELS IMPLY PARTLY TO MOSTLY CLOUDY TODAY. FIRST BATCH OF LOW
CLOUDS IN SW PA WILL SHRINK AS IT ADVECTS ACROSS THE STATE.
TEMPERATURE WISE CLOSE TO NORMAL.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
ANY SHOWER ACTIVITY THAT DEVELOPS SHOULD FADE FAST AROUND SUNSET.
BUILDING 5940M RIDGE IN SOUTHERN US AND BLOCKING RIDGE TO OUR
NORTH. WE ARE STUCK IN THE SQUEEZE PLAY BETWEEN THEM. AN ANEMIC
FRONTAL SYSTEM TRIES TO PUSH THROUGH THE REGION. SREF LARGER SCALE
MODELS SHOW SOME SURGE OF SLIGHTLY ABOVE NORMAL PW AND SOME CAPE
INTO WESTERN PA. POPS SHOULD DROP OFF TO EAST AS THIS SYSTEM WILL
WEAKEN AS IT MOVES BENEATH THE BLOCK. BEST CHANCE...AS MENTIONED
BELOW FOR SEVERAL TENTHS WOULD BE IN WEST VERY LIGHT RAINFALL IN
EASTERN AREAS.
PREVIOUS: PASSAGE OF SHORTWAVE AND COOLING OF BLYR SHOULD CAUSE
ANY EARLY EVENING SHOWERS TO DIMINISH SHORTLY AFTER SUNSET.
HOWEVER...APPROACH OF UPPER LOW AND ASSOC LL JET/PLUME OF
ANOMALOUS PWATS COULD SPREAD SHRA/TSRA INTO THE NW MTNS TOWARD
DAWN WED.
HAVE RAISED POPS MARKEDLY ACROSS THE AREA WED...AS MDLS NOW IN
AGREEMENT WITH TIMING OF LL JET/PLUME OF ANOMALOUS PWATS. BLEND OF
OPER AND ENSEMBLE GUIDANCE SUGGESTS MOST LIKELY RAINFALL WED WILL
RANGE FROM LESS THAN 0.10 INCHES SE OF HARRISBURG...TO ARND A HALF
INCH ACROSS WARREN CO. HOWEVER...MUCH HIGHER LOCALIZED AMTS ARE
LIKELY ACROSS THE W MTNS...WHERE ENVIRONMENT OF MODERATE INSTABILITY
AND HIGH PWATS WILL MAKE LOCALLY HVY TSRA POSSIBLE. CONVECTION-
ALLOWING MDLS SUPPORT THIS SCENARIO WITH SPOT AMTS OF ARND 2
INCHES ON WED ACROSS THE W MTNS. A MORE STABLE MARITIME AIR MASS
OVR EASTERN PA WILL MAKE TSRA UNLIKELY THERE.
GEFS 925 TEMPS ARE SUPPORTIVE OF HIGH TEMPS WED FROM THE M70S OVR
THE ALLEGHENY PLATEAU...TO THE L80S OVR THE SUSQ VALLEY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS
ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA
AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON
00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH
PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE
THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO
HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS
ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH
MAXES MAINLY IN THE 70S.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL GIVE WAY TO FOG AND LOWERING VSBYS OVERNIGHT
UNDER CLEAR SKIES AND LIGHT WINDS. EXPECT WIDESPREAD MVFR TO IFR
VSBYS AND CIGS TO DEVELOP OVERNIGHT AT MOST CENTRAL AND NORTHERN
AIRFIELDS. HOWEVER...HAVE NOT INCLUDED FOG IN THE LOWER
SUSQUEHANNA TAFS OF KMDT AND KLNS...AS CONFIDENCE OF FORMATION IS
LOWER. IF FOG DOES DEVELOP...LIKELY TO BE IN THE MVFR RANGE AT
THESE LOCATIONS.
CURRENT TIMING OF FOG IS FOR DEVELOPMENT AROUND 07Z IN MOST
LOCATIONS...WITH THE DENSEST FOG BETWEEN 09Z AND 12Z.
AFTER MORNING FOG...EXPECT GENERALLY VFR CONDITIONS. THERE IS A
THREAT FOR SHRA/TSRA...MOST LIKELY IN THE SOUTHWEST AND LEAST
LIKELY IN THE NORTHEAST.
A VERY SLOW APPROACHING UPPER LOW WILL SLOWLY INCREASE CHANCES FOR
DAILY SHOWERS AND POTENTIAL AFTERNOON TSRA FOR THE BALANCE OF THE
WEEK. CURRENTLY...LATER WEDNESDAY AND THURSDAY LOOK LIKE THE
HIGHEST LIKELIHOOD OF PRECIPITATION...WITH SURFACE FRONT CROSSING
THE REGION.
OUTLOOK...
TUE...MORNING FOG...THEN MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS.
SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT DECREASING CHANCES.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...GRUMM
SHORT TERM...GRUMM/FITZGERALD
LONG TERM...FITZGERALD
AVIATION...JUNG/GARTNER
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1111 PM MDT MON AUG 18 2014
.UPDATE...
ISSUED AT 806 PM MDT MON AUG 18 2014
00Z KUNR SOUNDING SHOWED A BIT OF MUCAPE. COUPLE OF WEAK
SHORTWAVES OVER SOUTH CENTRAL MT/NORTHWEST WY WILL MOVE EAST
THROUGH THE SOUTHWEST THIRD OF THE CWA OVERNIGHT BRINGING WITH IT
ISOLATED TSRA. LATEST HRRR SEEMS TO PICK UP ON THIS AS WELL AS
CURRENT RADAR TRENDS TO OUR WEST. WILL SPREAD POPS FROM CURRENT
RADAR RETURNS THROUGH SOUTHWEST THIRD OF CWA TO ACCOUNT WITH UPDATE.
&&
.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 300 PM MDT MON AUG 18 2014
CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER FAR NORTHERN MN
WITH HIGH PRESSURE OVER CENTRAL MT. UPPER LEVEL ANALYSIS SHOWS
TROF OVER SOUTH CENTRAL CANADA...WITH NORTHWESTERLY FLOW OVER MOST
OF THE NORTHERN HIGH PLAINS. DRIER AIR IS IN PLACE ACROSS THE AREA
FOR TODAY...WITH DEWPOINTS MOSTLY IN THE UPPER 40S AND 50S.
SHOWERS AND STORMS THIS AFTERNOON HAVE STAYED TO THE NORTH AND
SOUTH OF THE CWA...WITH A FEW STRONG STORMS OVER THE NEB PANHANDLE
RIGHT NOW. TEMPS ARE IN THE UPPER 79S TO UPPER 80S WITH BRISK
NORTHWESTERLY WINDS ACROSS MUCH OF THE PLAINS. THESE WINDS WILL
BEGIN TO DIMINISH BY EARLY EVENING.
UNSETTLED WEATHER WILL RETURN LATER ON TUESDAY AND PERSIST AT TIMES
THROUGH THE END OF THE WEEK AS HIGH PRESSURE ALOFT MOVES INTO THE
SOUTHEASTERN CONUS AND A BROAD TROF DEVELOPS OVER THE WESTERN
STATES. DAILY CHANCES FOR SHOWERS AND STORMS CAN BE EXPECTED...
ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS.
FOR TONIGHT...SKIES WILL BE CLEAR TO PARTLY CLOUDY. A WEAK
DISTURBANCE IN NORTHWEST FLOW COULD PRODUCE A FEW SHOWERS AND
POSSIBLY A STORM LATE TONIGHT INTO EARLY TUESDAY OVER THE BLACK
HILLS AREA. WINDS WILL BECOME LIGHT THIS EVENING AND THEN SWITCH TO
THE SOUTHEAST OVERNIGHT INTO TUESDAY MORNING AS HIGH PRESSURE PASSES
OVER AND EVENTUALLY EAST OF THE AREA.
WARMER AIR WILL RETURN ON TUESDAY AS SOUTH-SOUTHEAST WINDS INCREASE.
HIGHS WILL BE IN THE MID 80S TO AROUND 90 DEGREES ACROSS THE
PLAINS...MOSTLY 80S OVER THE BLACK HILLS. A MORE WIDESPREAD CHANCE
FOR STORMS WILL RETURN LATE TUESDAY AND ESPECIALLY TUESDAY NIGHT AS
FLOW ALOFT TURNS SOUTHWESTERLY OVER THE HIGH PLAINS. THE
SOUTH-SOUTHEAST WINDS WILL ALSO BRING LOW LEVEL MOISTURE BACK INTO
THE AREA...WITH INCREASING INSTABILITY INTO TUESDAY NIGHT. WILL
GENERALLY KEEP POPS AS IS LATE TUESDAY INTO TUESDAY NIGHT. THE
THREAT FOR SEVERE STORMS STILL LOOKS RELATIVELY LOW. HOWEVER...WITH
SUFFICIENT INSTABILITY AROUND...ISOLATED STRONG TO MARGINALLY SEVERE
STORMS WITH HAIL AND GUSTY WINDS ARE CERTAINLY POSSIBLE LATE IN THE
AFTERNOON INTO THE EVENING.
&&
.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 300 PM MDT MON AUG 18 2014
MEAN WESTERN NOAM TROUGHING WILL PERSIST IN THE PERIOD...WITH
MASSIVE EASTERN NOAM RIDGING ENSUING TOWARD THE END OF THE WEEK.
THIS WILL SUPPORT A LOCAL PATTERN CHANGE AS LOWER HEIGHTS AND MUCH
COOLER TEMPS SPREAD OVER THE NORTHERN PLAINS BY THIS WEEKEND...PER
THE WESTERN CONUS TROUGH PHASING WITH A LONG WAVE NORTHERN STREAM
TROUGH. ACTIVE SW FLOW CAN BE EXPECTED TO SUPPORT NEAR DAILY
CHANCES FOR PRECIP THROUGH THE PERIOD...WITH THE WESTERN CONUS
TROUGH SHIFTING EAST OVER THE NORTHERN PLAINS BY LATE THIS
WEEKEND.
HAVE RETAINED DAILY CHANCES FOR SHRA/TS WITH A WAVERING FRONTAL ZONE
OVER THE REGION THROUGH THUR. COLD FRONT WILL SHIFT SE TROUGH THE
REGION FRIDAY...WITH CAA SPREADING ACROSS THE REGION VIA GUSTY NW
WINDS. CYCLONIC DISTURBED SW FLOW WILL PERSIST THROUGH THE WEEKEND.
HOWEVER...GIVEN SIGNALS FOR THE BEST LSA BEING NW OF THE FA...WITH
MORE DIURNALLY DRIVEN CHANCES FOR CONVECTION...HAVE BIASED POPS MORE
TOWARD CLIMO NUMBERS THIS WEEKEND..ESP GIVEN CONVECTIVE NATURE TO
PRECIP.
AS FOR TEMPS...SEASONAL NUMBERS WILL PERSIST THROUGH THURS...WITH
COOLING CONDITIONS FRI-SUN. TEMPERATURES ARE PROGGED TO BE 5 TO 15
DEGREES BELOW SEASONAL NORMS BY SUNDAY AND MONDAY...ESP HIGH
TEMPERATURES. HAVE CONTINUED TO ADD A NEGATIVE BIAS PER HIGHS
SAT-MONDAY...WITH MANY PLACES LIKELY STRUGGLING TO REACH 70 ACROSS
THE NORTHERN HALF SUNDAY AND MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1109 PM MDT MON AUG 18 2014
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. A
WARM FRONT WILL SHIFT NORTH TONIGHT AND POSSIBLY SUPPORT ISOLATED
TSRA. ADDITIONAL TSRA WILL DEVELOP LATER TUESDAY AFTERNOON INTO
TUESDAY NIGHT WITH LOCAL MVFR CIGS/VSBYS IN THE STRONGEST STORMS.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
UPDATE...HELGESON
SHORT TERM...26
LONG TERM...JC
AVIATION...HELGESON
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
1033 PM EDT WED AUG 20 2014
.DISCUSSION...LINGERING SHOWERS...ASSOCIATED WITH THE DECAYING
CONVECTIVE COMPLEX...WILL DIMINISH AND SHOULD GIVE WAY TO AREAS OF
FOG BEFORE DAYBREAK. ADJUSTED POPS FOR THE REST OF THE NIGHT TO
RELFECT THIS. HOURLY TEMPS ADJUSTED DUE TO RAIN COOLED AIR...WITH A
FEW TWEAKS NEEDED ON MIN TEMPS.
HRR AND RAP MODEL DELAY THE ONSET OF CONVECTION FOR THURSDAY
MORNING...SO POP GRIDS WERE ALSO LOWERED TO SHOW THIS DELAY.
ALSO...DROPPED ANY MENTION OF THUNDERSTORMS FROM 04Z TO 12Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 72 94 72 95 / 30 20 10 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 91 71 92 / 40 30 10 20
OAK RIDGE, TN 67 91 71 92 / 30 30 10 20
TRI CITIES AIRPORT, TN 66 87 66 88 / 60 50 30 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
319 PM CDT TUE AUG 19 2014
.DISCUSSION...
UPPER FLOW IS NORTHWESTERLY THIS AFTERNOON WITH A SHORTWAVE AXIS IN
PLACE FROM LAKE SUPERIOR SW THROUGH IO. AFTERNOON RADAR DEPICTS AN
IMPULSE TO OUR NW WHICH WILL SWING OUR WAY OVERNIGHT. MID LEVEL
RIDGING THIS AFTERNOON IS EXPECTED TO VACATE THE AREA BY EVENING.
THIS WILL ACT TO PROMOTE A LITTLE EXTRA INSTABILITY OVERNIGHT.
LATEST HRRR SHOWS THAT AN AREA OF CONVECTION WILL ENTER OUR
NORTHWESTERN COUNTIES BETWEEN 01Z AND 03Z THIS EVENING. THE
CONVECTION WILL THEN SPREAD SOUTHEAST BUT WILL FRAGMENT AND
WEAKEN. WILL GO AHEAD AND INCLUDE 30-40 POPS FOR TONIGHT. A FEW
OF THE STORMS COULD BECOME STRONG...PARTICULARLY ACROSS WESTERN
AREAS THIS EVENING. OTW...WARM AND HUMID CONDITIONS TO CONTINUE
OVERNIGHT. LOWS WILL GENERALLY BE IN THE LOWER 70S...UPPER 60S
PLATEAU.
NORTHWESTERLY FLOW WILL CONTINUE THROUGH WEDNESDAY. ASSOCIATED
IMPULSES LOOK WEAK WITH THE LIMITED ENGAGEMENT OF APPRECIABLE
MOISTURE. STILL THOUGH...CAP TO WEAKEN DURING THE AFTERNOON AND
WILL THEREFORE INCLUDE SLIGHT POPS.
FOR THURSDAY AND BEYOND THE PATTERN WILL CHANGE AND MORPH INTO A
STRENGTHENING UPPER LEVEL RIDGING REGIME. BY THE WEEKEND...THE UPPER
RIDGING WILL EXPAND OVER THE SOUTHEASTERN U.S. WITH THE UPPER HIGH
CENTERED SOMEWHERE NEAR THE MS DELTA. THERMAL RIDGING TO
STRENGTHEN AS WELL WITH SEPARATION OCCURRING ACROSS THE
SOUTHEASTERN U.S. BY EARLY NEXT WEEK. THIS ALL EQUATES TO THE
HOTTEST WEATHER WE HAVE SEEN ALL SUMMER. A MARKED INCREASE IN
HUMIDITY LEVELS LOOKS SOMEWHAT QUESTIONABLE. MODELS HANG ON TO
UPPER 60S AFTERNOON DEWPOINTS. THE LOWER LEVEL WIND FETCH LOOKS TO
BE A BIT MORE LAND BASED AND THE HEIGHTENED LOWER LEVEL MOISTURE
RETURNS LOOK RATHER SHALLOW IN DEPTH. THIS WILL ALLOW SOME
AFTERNOON MIXING OF LOWER UPPER 60S DEWPOINTS DOWNWARD.
THEREFORE...THE HEAT INDEX INFLUENCE WILL BE IN PLACE BUT WILL BE
KEPT AT A RESPECTABLE AND NON-HIDEOUS LEVEL.
AS FOR CONVECTION CHANCES DURING THE EXTENDED...MRH FIELDS LOOK TO
BE IN THE 40-50% RANGE. 18Z CAP EROSION LOOKS LIKE IT WILL BE HARD
PRESSED TO HAPPEN AS THE MID LEVELS WARM UNDERNEATH THE STRONG
RIDGE. WILL THEREFORE BE LEAVING POPS OUT OF THE FCST...FOR THE MOST
PART.
FOR TEMPERATURES...HIGHS IN THE LOWER TO MID 90S FOR THE NEXT FEW
DAYS. THEN...WE WILL SEE MID TO UPPER 90S FOR THE WEEKEND AND NEXT
WEEK. OVERNIGHT LOWS WILL GENERALLY BE IN THE LOWER 70S FOR THE NEXT
FEW DAYS...MID 70S FOR THE WEEKEND AND NEXT WEEK. OF COURSE...A
LITTLE COOLER THROUGHOUT THE FCST FOR THE PLATEAU AREA.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 73 93 74 95 / 30 20 20 05
CLARKSVILLE 71 94 72 95 / 40 20 20 05
CROSSVILLE 67 88 68 90 / 30 30 20 20
COLUMBIA 72 94 73 95 / 30 20 10 0
LAWRENCEBURG 71 95 71 95 / 30 20 10 0
WAVERLY 71 94 72 95 / 40 20 10 05
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1131 PM CDT MON AUG 18 2014
.DISCUSSION...
UPDATED FOR 06Z AVIATION DISCUSSION
&&
.PREV DISCUSSION... /ISSUED 921 PM CDT MON AUG 18 2014/
UPDATE...
A CLUSTER OF SHOWERS AND THUNDERSTORMS ARE SKIRTING PHILLIPS
COUNTY ARKANSAS AND COAHOMA COUNTY MISSISSIPPI AT THIS TIME.
LATEST HRRR SHOWS THAT THE AREA FROM COAHOMA COUNTY TO MONROE
COUNTY MISSISSIPPI COULD CONTINUE SEE THIS ACTIVITY INTO THE
OVERNIGHT HOURS. OTHERWISE...EXPECT MAINLY DRY CONDITIONS. WILL
ADJUST POPS OTHERWISE REST OF THE FORECAST LOOKS GOOD.
KRM
DISCUSSION... /ISSUED 253 PM CDT MON AUG 18 2014/
SKIES ARE PARTLY CLOUDY OVER MUCH OF THE FORECAST AREA THIS
AFTERNOON WITH TEMPERATURES RANGING FROM THE LOWER 70S TO MID 80S.
SHOWERS AND A FEW THUNDERSTORMS CONTINUE TO MOVE ACROSS PORTIONS
OF THE FORECAST AREA. EARLIER THIS AFTERNOON WE HAD SOME HEAVY
RAINFALL OVER PORTIONS OF WEST TENNESSEE WITH 3 TO 5 INCHES OF
RAIN FALLING IN A FEW LOCATIONS. THE UPPER LEVEL DISTURBANCE WHICH
HELPED PRODUCE ALL THE THUNDERSTORM ACTIVITY WAS MOVING ACROSS
NORTH MISSISSIPPI THIS AFTERNOON. AS THIS DISTURBANCE CONTINUES TO
MOVE EAST INTO NORTH ALABAMA...THUNDERSTORMS WILL DECREASE IN
COVERAGE TONIGHT.
MEANWHILE...A WEAK FRONTAL BOUNDARY WAS LOCATED JUST NORTH OF THE
FORECAST AREA. AS IT BEGIN TO MOVE NORTH TONIGHT...SOME ADDITIONAL
THUNDERSTORMS MAY MOVE INTO NORTHWEST SECTIONS OF THE FORECAST
AREA OVERNIGHT. AS THE FRONT MOVES NORTH TUESDAY...THE CHANCE OF
THUNDERSTORMS WILL BE CONFINED TO MAINLY NORTHERN AND EASTERN
SECTIONS OF THE FORECAST AREA. TEMPERATURES WILL START TO BECOME
QUITE WARM ON TUESDAY WITH HIGHS IN THE LOW TO MID 90S.
BY WEDNESDAY...AN UPPER LEVEL RIDGE WILL START TO BUILD INTO THE
SOUTHEAST AND SOUTH CENTRAL U.S. THIS WILL BRING AN EXTENDED
PERIOD OF DRY WEATHER TO THE FORECAST AREA WITH NO RAIN EXPECTED
FROM WEDNESDAY THROUGH NEXT MONDAY. IN ADDITIONAL...TEMPERATURES
WILL BE AS HOT IF NOT HOTTER THAN WE HAVE SEEN THIS SUMMER WITH
HIGH TEMPERATURES IN THE MID TO UPPER 90S FROM WEDNESDAY THROUGH
NEXT MONDAY. HEAT INDEX VALUES MAY EXCEED 105 AT TIMES DURING THIS
PERIOD SO THERE MAY BE A NEED FOR A HEAT ADVISORY LATER THIS WEEK.
ARS
&&
.AVIATION...
VFR CONDS ACROSS THE REGION ATTM. PATCHY FOG WILL DEVELOP LATER
TONIGHT. LOW CLOUDS ARE POSSIBLE AT KMKL AND KTUP TUESDAY MORNING
THOUGH CONFIDENCE IS TOO LOW FOR A BKN DECK ATTM. UPPER RIDGE WILL
START BUILDING IN ON TUESDAY AND AREAL COVERAGE OF SHRAS/TSRAS
WILL BE TOO LOW TO MENTION VCTS. WINDS WILL BE LIGHT OVERNIGHT AND
WSW 7-10 KTS ON TUESDAY DIMINISHING AFTER SUNSET.
SJM
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1130 PM CDT MON AUG 18 2014
.AVIATION...
/06Z TAFS/
Convective activity has moved out of the area. VFR ceilings will
continue over all terminals through next 24 hours. Isolated
thunderstorms will be possible over the area through the next 24
hours, however the coverage does not warrant their inclusion in the
TAFs at this time. Due to the amount of rainfall that fell over the
southern terminals during the last 24 hours, MVFR visibilities are
likely to develop over the southern terminals before sunrise,
improving to VFR by mid-morning.
&&
.PREV DISCUSSION... /ISSUED 615 PM CDT MON AUG 18 2014/
.AVIATION...
/00Z TAFS/
As of 6 pm, there is an area of widespread rainfall with embedded
thunderstorms south of KABI and KSJT and affecting only the southern
terminals. VFR conditions are expected to continue through the next
24 hours at all terminals. Isolated to scattered thunderstorms are
possible through mid-evening over the southern terminal. Any
thunderstorms that occur will be capable of producing variable and
gusty winds. Thunderstorms are expected to occur again Tuesday
morning, mainly over the southern terminals.
&&
.PREV DISCUSSION... /ISSUED 350 PM CDT MON AUG 18 2014/
.SHORT TERM...
(Tonight and Tuesday)
Low confidence forecast across West Central Texas for the next 24
hours. Remnant Mesoscale Convective Vortex (MCV) continues to
remain nearly stationary across Sterling County early this
afternoon, and buried within a larger scale mid level shear axis
stretching across much of the area. Much like we saw on Sunday, as
the main morning area of showers and storms slowly winds down from
Abilene to Brownwood, more scattered convection is developing
along the periphery of the MCV where better heating is taking
place.
Biggest question in the forecast concerns tonight and Tuesday
rain chances. As the low level jet intensifies towards midnight,
expect to see another round of showers and storms form near the
center of the MCV and along its eastern flank. MCV is definitely
weaker today than it was yesterday, and should continue to slowly
wind down. How strong it remains tonight, where it ends up, and
what kind of storm coverage it can actually generate is highly
uncertain though. Models not a lot of help, with even the TTU WRF
and the HRRR models struggling in this highly mesoscale situation.
At this point, will bump pops to chance for most of the area,
knowing that some areas may miss out and others may see some
decent rainfall. Some of this area has seen rainfall totals in the
1 to 3 inch range, so if the rain can train over these areas, than
a flood threat becomes more pronounced. This will need to be
monitored through tonight.
07
.LONG TERM...
(Tuesday night through next Monday)
A mainly dry forecast expected for the extended period.
By Tuesday evening...the 500mb ridge that is currently centered
near Florida will expand farther west into Texas, pushing the
shear axis over the top of our CWA farther west as well. In
addition, by Tuesday night, 250mph ridging will move in over the
top of the region out of the southwest. These two factors point to
decreasing chances of precipitation overall for the area by
Tuesday night. However, we have left an area of slight chance PoPs
in for Tuesday evening. The combination of the previously
mentioned upper level shear axis and MCV is expected to result in
additional thunderstorm activity tomorrow afternoon. And although
these features are expected to be drifting to the west, there
could still be lingering activity for areas mainly south and west
of a Sterling City to San Angelo to Sonora line.
By Wednesday, upper level ridging will be in place across our
forecast area, effectively ending rain chances through the end of
the forecast period, and allowing temperatures to remain warm in
the mid to upper 90s for highs, and generally lower to mid 70s for
lows.
20
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 72 94 71 97 74 / 30 30 5 5 5
San Angelo 71 93 72 95 74 / 30 30 10 5 5
Junction 73 92 73 93 73 / 30 30 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1135 PM EDT WED AUG 20 2014
.SYNOPSIS...
A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST
OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST
ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE
REGION EACH DAY. THE FRONT SHOULD SHIFT BACK SOUTH OF THE REGION
SATURDAY BRINGING A RETURN TO COOLER WEATHER FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 1120 PM EDT WEDNESDAY...
MLCAPES OVER 1500 J/KG STILL LINGERING OVER THE PIEDMONT LATE THIS
EVENING KEEPING CONVECTION ONGOING FROM THE NC/VA LINE NORTH INTO
BUCKINGHAM COUNTY. AIRMASS HAS BEEN WORKED OVER ACROSS THE
MTNS...AND DESPITE A STRONGER WAVE DEPICTED BY LATEST RAP ANALYSIS
OVER KY...NOT SEEING MUCH OF ANYTHING EXCEPT ISOLATED/WIDELY
SCATTERED SHOWER THREAT THROUGH 3 AM OUT OVER FAR SW VA INTO NW
NC. THINK THE CONVECTION OUT EAST WILL EXIT THE CWA BY 1 AM.
SKIES WILL BE VARIABLY CLOUDY WITH LOTS OF HIGH CLOUDINESS ACROSS
THE WEST AND SOUTH. CLEARING TAKES PLACE INTO EARLY MORNING OUT
EAST...WITH MORE CLOUDS ARRIVING INTO THE APPALACHIANS AHEAD OF
THE NEXT SHORTWAVE MOVING OVER ILLINOIS THIS EVENING. MODELS HAVE
SLOWED TIMING DOWN SOME WITH ONSET OF NEXT ROUND OF SHOWERS IN THE
MTNS...SO DELAYED CHANCES A COUPLE OF HOURS.
FOG MAY BE MORE OF AN ISSUE OUT EAST IF/WHEN IT CLEARS ESPECIALLY
WHERE IT RAINED. FOR NOW KEPT IN PATCHY FOG...WITH AREAS CLOSER TO
BUCKINGHAM COUNTY. LOW TEMPS REMAIN MUGGY IN THE 60S.
WEAK RESIDUAL FRONT WILL LIFT BACK NE ON THURSDAY AS THE WAVE CHANNEL
ALOFT AROUND THE RIDGE TO THE SW AMPLIFIES A BIT AND STARTS TO SHIFT
NORTH AS WELL. MODELS BRING ANOTHER IMPULSE QUICKLY SE OUT OF THE
UPSTREAM CONVEYER BELT AND DRIVE IT TOWARD THE NW COUNTIES
THURSDAY MORNING SIMILAR TO TODAY...PERHAPS JUST A BIT SLOWER.
HOWEVER LIFT WILL BE ENCOUNTERING DEEP NW FLOW SO UNCERTAIN AS TO
HOW FAR THIS COMPLEX MAY GET BEFORE FADING. THUS RUNNING WITH
INCREASING CHANCE POPS THURSDAY MORNING...MAINLY BLUE RIDGE
WEST...WITH HIGHEST ACROSS SE WEST VA. EXPECT EARLY CONVECTION TO
AGAIN FADE CROSSING THE RIDGES AS WE SLIP IN BETWEEN WAVES BEFORE
BETTER INSTABILITY/OUTFLOW HELPS REDEVELOP AT LEAST SCATTERED
AFTERNOON COVERAGE MOUNTAINS...AND ISOLATED OUT EAST WHERE
DOWNSLOPE ALOFT WILL BE STRONGER. THEREFORE TRIMMED BACK POPS TO
MORE CHANCE NATURE GIVEN TRENDS OF LATE AND LACK OF MUCH LIFT
THURSDAY AFTERNOON WITH THE NEXT WAVE IN OHIO. WARMING ALOFT AND
WESTERLY WINDS SHOULD COMBINE WITH SUNSHINE TO PUSH TEMPS ABOVE 90
SE WITH 80S MOST OTHER SPOTS PENDING EARLY CLOUDS.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 245 PM EDT WEDNESDAY...
FORECAST AREA STAYS IN BROAD NORTHWEST SYNOPTIC FLOW. PROBABILITY
OF PRECIPITATION WILL DEPEND ON WHEN SHORT WAVES COME THROUGH.
SHOWERS AND THUNDERSTORMS THAT CROSS THE COUNTY WARNING AREA
DURING THE LATE NIGHT OR EARLY MORNING...OR UPSTREAM CLUSTERS OF
STORMS THAT SPREAD CLOUDS DOWNSTREAM OVER US WILL DIMINISH THE
AVAILABLE INSTABILITY.
MODELS HAVE AXIS OF BEST LIFT SHIFTING JUST NORTH OF THE FORECAST
AREA ON FRIDAY. THIS MAY LIMIT THE COVERAGE OF PRECIPITATION FOR
FRIDAY THROUGH SATURDAY. BUT SURFACE BOUNDARY POSSIBLY MOVING SOUTH
THROUGH THE EASTERN PART OF THE FORECAST AREA ON FRIDAY MAY TRIGGER
SHOWERS AND THUNDERSTORMS. PRECIPITABLE WATER VALUES REMAIN HIGH
THROUGH THE PERIOD. LARGE RAINFALL RATES WILL BE POSSIBLE IN ANY OF
THE STORMS.
EXPECTING MUGGY CONDITIONS OVERNIGHT WITH DEW POINTS REMAINING WELL
INTO THE 60S. 850 TEMPERATURES ON THE EASTERN SIDE OF THE FORECAST
AREA WILL BE COOLER THAN IN THE WEST. OVERALL PRECIPITATION AND
CLOUD COVER WILL HOLD TEMPERATURES AT OR JUST BELOW NORMAL FOR
MAXIMUM TEMPERATURES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 300 PM EDT WEDNESDAY...
LARGE UPPER RIDGE BUILDS FROM THE LOWER MISSISSIPPI VALLEY. 500 MB
HEIGHTS OVER THE FORECAST AREA BEGIN TO RISE ON TUESDAY WITH THE
RIDGE CENTERED OVER THE TENNESSEE VALLEY.
SURFACE HIGH PRESSURE WILL BE OVER NEW ENGLAND AND WEDGED DOWN THE
APPALACHIANS THROUGH TUESDAY. BY THURSDAY A STRONG BERMUDA HIGH WILL
BE IN PLACE.
CHALLENGING TO TIME SHORT WAVES COMING OVER THE TOP OF THE RIDGE.
WPC WAS FAVORING A BLEND OF ENSEMBLE GFS AND ECMWF THROUGH THE
PERIOD. THIS KEEPS FORECAST AREA IN A PERSISTENT CHANCE OF
PRECIPITATION THROUGH MONDAY NIGHT. AT THIS TIME WILL BE
EMPHASIZING SUNDAY NIGHT AS THE BEST CHANCE IN THIS TIME FRAME.
WILL BE WARMING UP CLOSER TO ABOVE NORMAL TEMPERATURES ASSOCIATED
WITH THE UPPER RIDGE ON WEDNESDAY.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
AS OF 720 PM EDT WEDNESDAY...
THERE IS A LARGE AREA OF CONVECTION TO THE WEST AND SOUTHWEST...
TOWARDS THE TENNESSEE VALLEY THIS EVENING. THERE IS ALSO ANOTHER
LINE OF STRONG THUNDERSTORMS ACROSS CENTRAL AND EASTERN VIRGINIA.
BOTH OF THESE STORMS ARE TRACKING TO THE SOUTHEAST. WE WILL NEED
TO WATCH THE STORMS TO THE WEST AS THEY MAY CLIP THE FORECAST AREA
FROM BLUEFIELD WV TO MOUNT AIRY NC EARLY. AT TAF TIME...THERE ARE
ONLY ISOLATED SHOWERS OVER THE FORECAST AREA...MAINLY EAST OF THE
BLUE RIDGE. THESE SHOWERS WILL FADE WITH SUNSET. THROUGH THE
OVERNIGHT...PATCHY DENSE FOG MAY DEVELOP IN MOUNTAIN VALLEYS AND
MORESO IN AREAS THAT SEE RAIN THIS EVENING.
FLOW ALOFT WILL REMAIN NORTHWESTERLY THURSDAY. IMPULSES TO THE
WEST WILL LIKELY BRING A ROUND OF SHOWERS AND THUNDERSTORMS TO THE
REGION TOMORROW. OUTFLOW BOUNDARIES FROM ACTIVITY SURROUND THE
FORECAST AREA THIS EVENING MAY ALSO GENERATE STORMS TOMORROW. THE
CHANCES FOR THUNDERSTORMS LOOKS GOOD WHILE TIMING CONFIDENCE IS
LOW. FOR NOW...WILL ONLY CARRY VICINITY STORMS IN THE AFTERNOON
FOR ALL SITES.
EXTENDED AVIATION...
UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY AND
INTERACTING WITH A STATIONARY FRONT OVER THE AREA FOR THE NEXT FEW
DAYS...RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS. DUE TO
THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND FOG
DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST
PRONOUNCED BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED
THAT A DEEPER EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS
UPCOMING WEEKEND. THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN
DURING THE DAYTIME PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD
MVFR CONDITIONS ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE
BANKING UP AGAINST THE EAST SIDE OF THE APPALACHIANS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/WP
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...MBS/RCS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
844 PM CDT WED AUG 20 2014
.UPDATE...
ISSUED AT 844 PM CDT WED AUG 20 2014
THE MAIN FOCUS CONTINUES TO BE ON THE CONVECTIVE TRENDS FOR THE
OVERNIGHT PERIOD AS THE LOW LEVEL JET STRENGTHENS INTO THE UPPER
MISSISSIPPI RIVER VALLEY REGION. AN INITIAL BAND OF LIGHT RAIN
SHOWERS HAS DEVELOPED ACROSS SOUTHWEST MINNESOTA AND NORTH CENTRAL
IOWA ALONG THE LEADING/EASTERN EDGE OF THE LOW LEVEL MOISTURE
TRANSPORT/WARM AIR ADVECTION WING. THESE SHOWERS HAVE BEEN VERY
LIGHT AND ARE NOT EXPECTED TO STRENGTHEN IN INTENSITY THROUGH THE
LATE EVENING HOURS.
THE MAIN FOCUS IS FURTHER WEST UNDER THE MAIN CORRIDOR OF BETTER
LOW LEVEL MOISTURE TRANSPORT THAT IS PUSHING UP INTO EASTERN SOUTH
DAKOTA AND FAR SOUTHWESTERN MINNESOTA. CONVECTION IS STARTING TO
DEVELOP ACROSS THIS CORRIDOR AND WILL INCREASE IN COVERAGE AND
TRACK EAST OVERNIGHT. THE PAST FEW RUNS OF THE HRRR SEEM TO BE
CATCHING UP TO THE CURRENT CONDITIONS AND SHOWING THIS TREND
BETTER WITH THE MAIN BATCH OF RAIN/CONVECTION COMING THROUGH
AROUND DAYBREAK TOMORROW MORNING. THEREFORE...HAVE BACKED OFF ON
PRECIPITATION CHANCES THROUGH THIS EVENING AND FOCUSED THEM MORE
ON THE EARLY MORNING HOURS ON THURSDAY. THE 21.00Z RAP SHOWS THE
MAIN BELT OF ELEVATED INSTABILITY RUNNING FROM EASTERN IOWA INTO
SOUTH CENTRAL SOUTH DAKOTA WITH A GRADUAL SHIFT NORTHWARD OF IT
OVERNIGHT. THE TREND IS FOR THIS INSTABILITY TO CONTINUALLY WEAKEN
AS THE NIGHT PROGRESSES WITH AROUND 1000 J/KG OF 0-3KM MUCAPE LEFT
BY DAYBREAK. WITH THE INCREASING LIFT THANKS TO THE LLJ...STILL
CAN NOT RULE OUT THAT A FEW OF THE STORMS COULD BECOME
STRONGER...BUT THE THREAT OF WIDESPREAD STRONG TO SEVERE WEATHER
APPEARS LOW.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 218 PM CDT WED AUG 20 2014
PRIMARY FORECAST CHALLENGE WILL BE SHOWER AND THUNDERSTORM TIMING
AND COVERAGE TONIGHT THROUGH THURSDAY AND THE POTENTIAL FOR
LOCALIZED FLOODING. CONVECTIVE CHANCES WILL CONTINUE TO BE A
CONCERN FRIDAY THROUGH THE WEEKEND AS WELL. HIGH RESOLUTION MODELS
BEGINNING TO CONVERGE ON A SOLUTION TONIGHT WHICH MATCHES WELL
WITH SYNOPTIC/MESOSCALE SIGNALS IN GLOBAL MODEL SUITE. WILL USE A
BLENDED MODEL SOLUTION WITH A SLIGHT PREFERENCE TOWARD THE ECMWF/
NAM AS THE GFS IS A BIT FASTER/FARTHER NORTH WITH FRONTAL PASSAGE
TOMORROW.
20.20Z SURFACE ANALYSIS SHOWS A LOW PRESSURE CENTER ACROSS
SOUTHWEST NE WITH ITS WARM FRONT DRAPED TO THE EAST ACROSS
SOUTHERN NE INTO NORTHWEST MO. ACTUAL CONVECTION HAS BEEN FURTHER
NORTH AND EAST ACROSS CENTRAL IA COINCIDENT WITH BEST MID-LEVEL
WARM AIR ADVECTION...MOISTURE CONVERGENCE AND ISENTROPIC LIFT.
SURFACE LOW IS PART OF A MUCH BROADER TROUGH THAT WILL SLOWLY LIFT
NORTH AND EAST TONIGHT THROUGH THURSDAY PLACING THE SURFACE WARM
FRONT ACROSS THE SOUTHERN FORECAST AREA BY 21.12Z. EXPECT A
NORTHWEST TO SOUTHEAST ORIENTED LINE OF CONVECTION TO DEVELOP LATE
THIS EVENING AHEAD OF THE FRONT AND MOVE NORTHEASTWARD ALIGNED
ALONG OR JUST NORTH OF THE MISSISSIPPI RIVER VALLEY BY DAYBREAK
THURSDAY.
ELEVATED CAPE OVERNIGHT GENERALLY REMAINS LESS THAN 1000
J/KG...BUT 0 TO 6 KM BULK SHEAR INCREASES TO NEAR 40 KTS BY 21.12Z
WITH IMPINGING 300 HPA JET STREAK. NOT EXPECTING WIDESPREAD
SEVERE...BUT COULD SEE SOME ISOLATED LARGE HAIL OR DAMAGING WIND
FROM THE STRONGEST STORMS. BIGGER CONCERN WILL BE HEAVY RAIN.
EXPECT STRONG MID-LEVEL MOISTURE TRANSPORT WITH PRECIPITABLE WATER
VALUES INCREASING TO NEAR 2.0 INCHES. SEE HYDROLOGY DISCUSSION FOR
MORE DETAILS.
20.12Z ECMWF/NAM SUGGEST WARM FRONT MAY STALL THURSDAY AFTERNOON
NEAR THE MISSISSIPPI RIVER VALLEY...RESULTING IN A PROLONGED
PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS WESTERN/CENTRAL WI.
INCREASED POPS IN THESE AREAS THROUGH THE AFTERNOON AND LOWERED
TEMPERATURES A HANDFUL OF DEGREES. SOUTH OF THE FRONT WILL WARM
NICELY WITH TEMPERATURES RISING INTO THE UPPER 80S TO NEAR 90
DEGREES.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 218 PM CDT WED AUG 20 2014
MAIN SURFACE TROUGH WILL SWEEP ACROSS THE FORECAST AREA THURSDAY
NIGHT...RESULTING IN DECREASING CONVECTION AND DRYING FROM WEST
TO EAST. HOWEVER...REGION WILL REMAIN IN WARM MOIST AIR MASS
RESULTING IN HIGH TEMPERATURES FRIDAY CLIMBING INTO THE MID TO
UPPER 80S WITH DEW POINT TEMPERATURES INTO THE LOWER 70S.
HARD TO PINPOINT A PROLONGED DRY PERIOD SATURDAY THROUGH WEDNESDAY.
500 HPA RIDGE BUILDS ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
WITH ITS AXIS SLIDING SLOWLY TO THE EAST THROUGH THE WEEK
RESULTING IN INCREASED SOUTHWEST FLOW ALOFT. A SERIES OF ILL-
RESOLVED EMBEDDED SHORT WAVES COMBINED WITH A WAVERING SURFACE
BOUNDARY WILL PROVIDE THE FOCUSING MECHANISMS FOR CONVECTION...
BUT TIMING AND COVERAGE UNCERTAINTY ABOUNDS. THIS ALSO WRECKS
HAVOC ON SEVERE POTENTIAL AND WILL NEED TO MONITOR SUBSEQUENT
MODEL RUNS. WILL FOLLOW ALL BLEND POPS FOR NOW HIGHLIGHTING 20 TO
50 PERCENT CHANCES FOR MEASURABLE RAIN EACH PERIOD.
TEMPERATURES THROUGH SUNDAY WILL REMAIN ON THE HIGH SIDE OF NORMAL
WITH DAILY HIGHS IN THE MID TO UPPER 80S AND POSSIBLY EVEN BREACHING
90 DEGREES GIVEN 925 HPA TEMPERATURES RANGING FROM 22 TO 27 C.
COULD SEE SOME RELIEF MONDAY/TUESDAY AS PRIMARY EASTERN PACIFIC
TROUGH ATTEMPTS TO MAKE SOME HEADWAY INTO STUBBORN UPPER LEVEL
RIDGE ACROSS THE GREAT LAKES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 652 PM CDT WED AUG 20 2014
COMPLICATED FORECAST SCENARIO FOR TONIGHT...WITH LOW PRESSURE AND WARM
FRONT STRETCHED SOUTHWEST OF KRST/KLSE. AS NIGHTTIME LOW LEVEL
MOISTURE TRANSPORT INCREASES...EXPECTING AN ARC OF SHOWERS/STORMS
TO ERUPT ACROSS SOUTHWEST MINNESOTA INTO NORTH CENTRAL IOWA. THESE
SHOULD TRACK EAST ACROSS THE AREA...REACHING KRST AFTER
MIDNIGHT...AND KLSE BY 08Z. MVFR CEILINGS/VISIBILITIES
LIKELY...AND IFR IS POSSIBLE THOUGH CONFIDENCE IS NOT HIGH ENOUGH
TO INCLUDE AT THIS POINT. PRECIPITATION SHOULD LINGER THROUGH THE
MID MORNING HOURS...BEFORE A WARM AIR MASS SURGE WILL CAP OFF THE
ENVIRONMENT AND GIVE WAY TO SCATTERED/BROKEN MID LEVEL CLOUDS.
&&
.HYDROLOGY...
ISSUED AT 218 PM CDT WED AUG 20 2014
URBAN AND SMALL STREAM FLOODING AND/OR LOCALIZED FLASH FLOODING IS
POSSIBLE TONIGHT THROUGH THURSDAY GIVEN MODEST FORCING IMPINGING
ON A VERY MOIST AIR MASS. PRECIPITABLE WATER VALUES NEAR 2.0
INCHES ARE NEAR THE 99TH PERCENTILE OF THE CLIMATOLOGICAL NORMAL
AT KMPX/KDVN. WARM CLOUD DEPTHS ARE ALSO VERY DEEP...WHICH SHOULD
RESULT IN EFFICIENT WARM RAIN PROCESSES. EVEN WITH RECENT RAINFALL...
REGIONAL SOILS ARE STILL RELATIVELY DRY AND SHOULD BE ABLE TO
ABSORB HEAVY RAINFALL UNLESS RATES BEGIN TO EXCEED 2 INCHES/HOUR
PER LATEST FLASH FLOOD GUIDANCE. CERTAINTY IN WIDESPREAD FLOODING
RAINS NOT HIGH ENOUGH AT THIS TIME TO WARRANT A FLASH FLOOD
WATCH...BUT FUTURE SHIFTS WILL NEED TO MONITOR THIS POTENTIAL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
UPDATE...HALBACH
SHORT TERM...ROGERS
LONG TERM....ROGERS
AVIATION.....ZT
HYDROLOGY....ROGERS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
252 PM CDT TUE AUG 19 2014
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 252 PM CDT TUE AUG 19 2014
WATER VAPOR IMAGERY COUPLED WITH RAP 500MB ANALYSIS SHOWING A MID-
LEVEL LOW OVER WESTERN UPPER MICHIGAN. COLD POOL ALOFT ASSOCIATED
WITH THE LOW PRODUCING WIDESPREAD CUMULUS/STRATOCUMULUS FIELD ACROSS
THE FORECAST AREA WITH RADAR EVEN SHOWING A FEW SHOWERS POPPING UP
ACROSS NORTHERN MN INTO NORTHERN WI. OTHERWISE...TEMPERATURE ACROSS
THE ARX FORECAST AREA WERE IN THE 70-80 DEGREE RANGE.
FOR TONIGHT...COULD SEE A FEW SHOWERS NORTHEAST OF I-94 THIS EVENING
BUT THEN EXPECTING CLOUDS TO DIMINISH LATE IN THE EVENING AND
THROUGH THE OVERNIGHT HOURS AS A RIDGE OF HIGH PRESSURE MOVES
OVERHEAD. THIS WILL SET UP FAVORABLE FOG POTENTIAL OVERNIGHT/EARLY
WEDNESDAY MORNING...ESPECIALLY FAVORED RIVER VALLEY LOCATIONS.
THINKING AREAS SOUTHWEST OF I-94 WILL BE MOST IMPACTED WHERE
CONFIDENCE IS HIGHER FOR CLEARING SKY CONDITIONS EXISTS. HELD OFF ON
DENSE FOG ADVISORY FOR NOW BASED ON INPUT FROM SURROUNDING
OFFICES...BUT EVENING FORECASTER WILL HAVE TO MONITOR CLOSELY FOR
POSSIBLE FOG HEADLINE. LOOK FOR LOWS TONIGHT IN THE MIDDLE 50S TO
THE LOWER 60S.
AFTER AREAS OF MORNING FOG...PLAN ON THE RIDGE OF HIGH PRESSURE TO
KEEP THE FORECAST AREA DRY THROUGH WEDNESDAY. AN APPROACHING WARM
FRONT FROM THE CENTRAL PLAINS/MID-MISSISSIPPI RIVER VALLEY WILL
LIKELY SPARK A FEW SHOWERS AND THUNDERSTORMS...BUT PRETTY CONFIDENT
THESE WILL REMAIN SOUTH OF THE AREA. OTHERWISE...EXPECTING HIGH
TEMPERATURES TO TOP OFF IN THE MID 70S TO THE LOWER 80S.
LOOK FOR SHOWERS AND THUNDERSTORMS TO BECOME LIKELY BY LATE
WEDNESDAY NIGHT AS THE WARM FRONT CONTINUES TO APPROACH THE REGION.
ALL MODELS SHOW 850MB MOISTURE TRANSPORT INCREASING INTO/OVER THE
FRONT...WITH BEST AXIS OF MOISTURE PLUME REMAINING JUST WEST OF THE
FORECAST AREA. IN FACT...THE GFS/NAM SHOWING PRECIPITABLE WATER
VALUES SURGING INTO THE 1.5-2 INCH RANGE. THIS COULD LEAD TO SOME
LOCALIZED HEAVIER RAINFALL AS WARM CLOUD LAYER DEPTH INCREASE TO
AROUND 4KM BY MORNING. MAY NEED TO MONITOR THE POTENTIAL FOR A FEW
SEVERE THUNDERSTORMS WITH LARGE HAIL INITIALLY WITH THE INCOMING
CONVECTION AS NAM INDICATING 1-6KM MUCAPE IN THE 2500-3500J/KG RANGE
COUPLED WITH 25-35KT BULK SHEAR.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 252 PM CDT TUE AUG 19 2014
MODELS SHOWING THE WARM FRONT PUSHING NORTHEAST THROUGH THE AREA ON
THURSDAY FOR THE CONTINUED LIKELIHOOD OF SHOWERS AND THUNDERSTORMS.
MODELS ALSO SHOWING 850MB MOISTURE TRANSPORT WANING THROUGH THE
MORNING HOURS AND EVENTUAL CAPPING ALONG AND WEST OF THE MISSISSIPPI
DURING THE AFTERNOON HOURS. AS SUCH...DIVIDED POPS INTO
MORNING/AFTERNOON TIME PERIODS. STILL LOOKING AT THE POTENTIAL FOR
SOME LOCALIZED HEAVY RAINFALL THROUGH THE MORNING HOURS WITH
PRECIPITABLE WATER VALUES LINGERING IN THE 1.5 TO 2 INCH RANGE.
OTHERWISE...LOOK FOR SUBSTANTIALLY MORE HUMID CONDITIONS AS DEW
POINTS CREEP UP INTO THE LOWER 70S. THESE DEW POINTS COMBINED WITH
DAYTIME HIGHS WELL INTO THE 80S FOR MOST OF THE AREA ARE EXPECTED
TO PRODUCE HEAT INDICES IN THE 90 TO 100 DEGREE...HIGHEST ALONG AND
WEST/SOUTH OF THE MISSISSIPPI/WISCONSIN RIVERS.
FOR THURSDAY NIGHT THROUGH THE REST OF THE PERIOD...FORECAST
CONFIDENCE WANES FAIRLY RAPIDLY. MODEL CONSENSUS SHOWS A MID-LEVEL
RIDGE TRYING TO ESTABLISH ITSELF OVER THE CENTRAL CONUS.
HOWEVER...MESSY FLOW WITH MONSOONAL TAP WILL BE IN PLACE ACROSS THE
INTERMOUNTAIN/PLAINS REGION. TIMING OF THESE WAVES PRETTY UNCERTAIN
AT THIS TIME. AS SUCH...WILL KEEP LOW-MEDIUM RANGE
SHOWER/THUNDERSTORM CHANCES IN THROUGH THE PERIOD. TEMPERATURES
THROUGH THE PERIOD LOOK TO STAY AT OR A FEW DEGREES ABOVE NORMAL
THROUGH THE WEEKEND...WITH PERHAPS SOME COOLING EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1222 PM CDT TUE AUG 19 2014
LOW STRATUS THIS MORNING AT KLSE AND KRST HAS LIFTED TO ABOVE 3000
FT AGL AND EXPECT VFR CONDITIONS TO PERSIST THROUGH THIS AFTERNOON
AND EVENING. OVERNIGHT SET-UP STILL VERY FAVORABLE FOR FOG WITH HIGH
PRESSURE BUILDING ACROSS THE REGION RESULTING IN CLEARING SKIES AND
CALM WIND. BASED ON LATEST MODEL GUIDANCE...BEGAN LIFR CONDITIONS AT
KLSE AT 08Z WITH IMPROVEMENT EXPECTED AFTER 15Z. FOG EXTENT AT KRST
A BIT LESS CERTAIN...SO WILL KEEP WITH THE IDEA OF VISIBILITY
REDUCTIONS TO 1 SM AT 10Z WITH THE POTENTIAL FOR FURTHER
RESTRICTIONS.
&&
.HYDROLOGY...WEDNESDAY NIGHT INTO THURSDAY
ISSUED AT 252 PM CDT TUE AUG 19 2014
THERE IS THE LIKELIHOOD FOR SHOWERS AND THUNDERSTORMS WITH THE
POTENTIAL FOR HEAVY RAINFALL WEDNESDAY NIGHT INTO THURSDAY MORNING.
EXPECTING FAIRLY WIDESPREAD 1/4 TO 3/4 INCH RAINFALL WITH LOCALIZED
GREATER THAN 1 INCH AMOUNTS. THIS RAINFALL COMBINED WITH RECENT
POCKETS OF HEAVY RAINS ACROSS PORTIONS OF THE FORECAST AREA COULD
LEAD TO SOME LOCALIZED FLOODING CONCERNS. WILL KEEP A CLOSE EYE ON
LOCALIZED FLOODING CONCERN AND THE POTENTIAL FOR A FLASH FLOOD WATCH
HEADLINE WEDNESDAY NIGHT INTO THURSDAY MORNING ONCE CONFIDENCE
INCREASES ON EXACTLY WHERE THE HEAVIER RAINFALL WILL OCCUR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...ROGERS
HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
411 AM CDT TUE AUG 19 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 411 AM CDT TUE AUG 19 2014
AREAS OF DENSE FOG HAVE DEVELOPED OVER PORTIONS OF CENTRAL WISCONSIN
EARLY THIS MORNING. A DENSE FOG ADVISORY HAS BEEN ISSUED FOR
JACKSON...CLARK...AND TAYLOR COUNTIES WHERE THE VISIBILITY HAS
FALLEN TO 1/4 MILE OR LESS. LOOK FOR THIS FOG TO DISSIPATE BETWEEN 8
AND 9 AM THIS MORNING.
LATEST WATER VAPOR IMAGERY SHOWED A VIGOROUS UPPER LEVEL TROUGH OVER
THE UPPER MISSISSIPPI RIVER VALLEY...PUSHING SOUTHEAST. SHOWERS
AND THUNDERSTORMS HAVE MOVED EAST OF THE FORECAST AREA EARLY THIS
MORNING. THE TROUGH WILL CONTINUE TO SWING ACROSS THE AREA TODAY
AND IS EXPECTED TO GENERATE SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS. NAM FORECAST SOUNDINGS SHOW TALL SKINNY CAPE
PROFILES TODAY WITH ONLY 400-500 J/KG OF SBCAPE NOTED. MESOSCALE
MODELS ARE REALLY NOT GENERATING MUCH CONVECTION THIS
AFTERNOON...MAINLY SHOWING SCATTERED SHOWERS FOR LOCATIONS NORTH
OF INTERSTATE 90. AFTER WE DESTABILIZE LATE THIS MORNING INTO THIS
AFTERNOON WE SHOULD SEE THE SCATTERED SHOWERS AND ISOLATED STORMS
DEVELOP. THIS ACTIVITY WILL THEN TAPER OFF LATE THIS AFTERNOON
INTO THIS EVENING WITH THE LOSS OF DAYTIME HEATING. PLAN ON HIGHS
TODAY RANGING FROM THE LOWER 70S OVER NORTH CENTRAL WISCONSIN TO
THE UPPER 70S ACROSS NORTHEAST IOWA. FOCUS TURNS TO DENSE FOG
POTENTIAL LATE TONIGHT INTO WEDNESDAY MORNING...ESPECIALLY ALONG
VALLEY LOCATIONS. SURFACE HIGH PRESSURE SETTLES OVER THE FORECAST
AREA LATE TONIGHT SETTING THE STAGE FOR LIGHT WINDS FROM THE
SURFACE THROUGH 4 KFT. WITH SKIES BECOMING MOSTLY CLEAR AND DEW
POINTS IN THE UPPER 50S TO LOWER 60S WE SHOULD SEE AREAS OF DENSE
FOG DEVELOP. ALSO...THE NAM FORECAST SOUNDING AT KLSE LOOKS VERY
FAVORABLE FOR A VALLEY FOG EVENT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 411 AM CDT TUE AUG 19 2014
AFTER SOME MORNING FOG...PARTLY TO MOSTLY SUNNY SKIES WILL BE THE
RULE ACROSS THE AREA ON WEDNESDAY AS LOW PRESSURE LIFTS NORTH OUT
OF THE CENTRAL PLAINS. THE LOW WILL PUSH A WARM FRONT INTO THE
FORECAST AREA WEDNESDAY NIGHT INTO THURSDAY MORNING...BRINGING A
VERY JUICY AIRMASS INTO THE REGION. PRECIPITABLE WATER VALUES
INCREASE TO 1.8 TO 2.1 INCHES AND WARM CLOUD DEPTH TO 4.4 KM. THE
STORMS DURING THIS TIMEFRAME. A BAND OF SHOWERS AND THUNDERSTORMS
LOOKS TO LIFT NORTHEAST ACROSS THE FORECAST AREA FROM LATE
WEDNESDAY NIGHT INTO THURSDAY MORNING. THE THUNDERSTORMS WILL BE
VERY EFFICIENT RAIN PRODUCERS AND COULD DROP 1 TO 2 INCHES OF
RAINFALL IN A SHORT AMOUNT OF TIME. THE WHOLE SYSTEM IS
PROGRESSIVE SO THIS SHOULD LIMIT FLOODING CONCERNS BUT GIVEN THE
AIRMASS CANNOT RULE OUT NEEDING SOME HYDROLOGY HEADLINES WEDNESDAY
NIGHT INTO TUESDAY MORNING. THE SHOWERS AND STORMS SHOULD LIFT
NORTHEAST THROUGH THE DAY ON THURSDAY LEAVING A VERY HUMID AIRMASS
ACROSS THE FORECAST AREA IN THE WAKE OF THIS ACTIVITY.
BEYOND THURSDAY THE FORECAST BECOMES CHALLENGING WITH MODELS IN
DISAGREEMENT ON HOW MUCH RIDGING BUILDS INTO THE FORECAST AREA.
THE ECMWF IS THE MOST AGGRESSIVE AND BUILDS HEAT ACROSS THE AREA
GOING INTO THIS WEEKEND. THE GFS KEEPS THE WARM FRONT LINGERING
OVER THE FORECAST AREA ON FRIDAY WITH CONTINUE CHANCES FOR HEAVY
RAINFALL. A HOT AIRMASS IS FOCUSED JUST SOUTH OF THE AREA GOING
INTO THIS WEEKEND AND IT WOULD TAKE MUCH TO GET THE STEAMY AIR
INTO NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN SO WILL HAVE TO
KEEP A VERY CLOSE EYE ON HOW MUCH RIDGING CAN BUILD OVER THE
AREA...AND WHERE THE FRONT SETS UP. CONVECTION WILL HAVE A HUGE
IMPACT ON TEMPERATURES AND THE LOCATION OF THE BOUNDARY. COOLER
AIR THEN LOOKS RETURN EARLY NEXT WEEK AS THE BOUNDARY IS PUSHED
TO THE SOUTH OF THE UPPER MISSISSIPPI RIVER VALLEY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1157 PM CDT MON AUG 18 2014
MAIN AREA OF CONVECTION HAS PASSED BY BOTH TAF SITES. THE WIND
SHIFT HAS YET TO COME THROUGH AND BASED ON THE 19.03Z RAP THIS
SHOULD PASS THROUGH LATE TONIGHT SWINGING THE WINDS AROUND TO THE
WEST AND THEN NORTHWEST. THE RAP BUFKIT SOUNDING ALSO NOW SHOWS
LITTLE POTENTIAL FOR SATURATION TO OCCUR BEHIND THE BOUNDARY
MAKING IT LOOK LESS LIKELY THAT FOG AND LOW LEVEL STRATUS WILL
FORM. GIVEN THAT BOTH SITES DID HAVE RAIN TONIGHT...WILL LEAVE
SOME MVFR VISIBILITIES IN THE FORECASTS IN THE EVENT THAT THE
WINDS DROP OFF SOME BEHIND THE FRONT. WITH ALL THE LOW LEVEL
MOISTURE FROM THE RAIN AND AS SOME HEATING STARTS AFTER
SUNRISE...DO EXPECT TO SEE SOME MVFR CEILINGS FORM BY MID MORNING
AND THE PERSIST INTO THE EARLY AFTERNOON BEFORE THESE LIFT TO VFR.
THESE CEILINGS SHOULD THEN REMAIN THROUGH THE AFTERNOON BEFORE
SCATTERING OUT LATE IN THE AFTERNOON OR EARLY EVENING.
&&
.HYDROLOGY...WEDNESDAY NIGHT INTO THURSDAY
ISSUED AT 411 AM CDT TUE AUG 19 2014
THERE IS THE POTENTIAL FOR THUNDERSTORMS WITH HEAVY RAINFALL
WEDNESDAY NIGHT INTO THURSDAY MORNING. THESE STORMS COULD PRODUCE 1
TO 2 INCHES OF RAINFALL WITH LOCALLY HIGHER AMOUNTS POSSIBLE. THIS
RAINFALL COMBINED WITH RECENT HEAVY RAINS ACROSS PORTIONS OF THE
FORECAST AREA COULD LEAD TO FLOODING CONCERNS. A FLASH FLOOD WATCH
MAY BE NEEDED WEDNESDAY NIGHT INTO THURSDAY MORNING ONCE CONFIDENCE
INCREASES ON EXACTLY WHERE THE HEAVIER RAINFALL WILL OCCUR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ017-029-
034.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
HYDROLOGY...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1157 PM CDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 315 PM CDT MON AUG 18 2014
FORECAST FOCUS IS ON RAIN TONIGHT AS UPPER SHORT WAVE PASSES
THROUGH THE REGION WITH A WARM AND HUMID AIRMASS IN PLACE. A
CLOSED LOW CUTS OFF OVER THE GREAT LAKES AS THIS WAVE ROUNDS THE
BASE OF THE LONG WAVE TROUGH. WITH WEAKER IMPULSES CIRCULATING
AROUND THE LOW...RAIN CHANCES LINGER INTO TUESDAY AS WELL.
19Z MESOANALYSIS SHOWS UPPER WAVE SPINNING INTO NORTHWEST MN...
HEADING SOUTHEAST. PLUME OF 70+ LOW LEVEL DEWPOINTS FROM EASTERN
IA UP INTO WESTERN WI AHEAD OF THE APPROACHING WAVE. ACTIVE
CONVECTION ONGOING FROM WEST CENTRAL INTO NORTHEAST WI...AND NEW
ACTIVITY GOING UP OVER NORTHEAST IA AND SOUTHEAST MN. ANTICIPATE
SCATTERED SHOWERS AND THUNDERSTORMS TONIGHT...WITH PERHAPS A BREAK
FOR A TIME EARLY THIS EVENING AFTER THIS FIRST INITIAL BAND.
PRECIPITABLE WATER SOMEWHAT ELEVATED AND WARM CLOUD DEPTH 3500+
METERS. ANY STORMS WILL BE PRODUCING HEAVY DOWNPOURS. DCAPE
SUGGESTS WIND POTENTIAL AS WELL.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 315 PM CDT MON AUG 18 2014
UPPER LEVEL LOW OVER THE GREAT LAKES SHIFTS EAST ON WEDNESDAY AS
UPPER RIDGING BUILDS INTO THE UPPER MIDWEST. A PATTERN SHIFT TO
MORE SOUTHWEST FLOW TAKES PLACE MID-WEEK WITH A LONG WAVE TROUGH
ESTABLISHING ITSELF OVER THE WESTERN CONUS. EVENTUAL RAIN CHANCES
LATER THIS WEEK...AND THE DEGREE OF WARMING...ARE TIED TO HOW THE
SHORT WAVE TROUGH ENERGY EJECTS NORTHEAST TOWARD OUR REGION.
MEDIUM RANGE MODELS DO SHOW SOME DIFFERENCES IN TIMING OF THESE
IMPULSES...SO CONFIDENCE NOT HIGH. BUT IT DOES APPEAR THE OVERALL
TREND OF WARM AND HUMID CONDITIONS WILL COME TO FRUITION. IT HAS
BEEN DRY LATELY...BUT THESE STORMS ONCE AGAIN LOOK TO HAVE
INGREDIENTS FOR HEAVY RAIN POTENTIAL. THIS WILL HAVE TO BE
MONITORED AS WE START TO ACCUMULATE SOME RAINFALL ON OUR RECENTLY
DRY SOILS...WILL A FLOOD WATCH EVENTUALLY BE NECESSARY?
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1157 PM CDT MON AUG 18 2014
MAIN AREA OF CONVECTION HAS PASSED BY BOTH TAF SITES. THE WIND
SHIFT HAS YET TO COME THROUGH AND BASED ON THE 19.03Z RAP THIS
SHOULD PASS THROUGH LATE TONIGHT SWINGING THE WINDS AROUND TO THE
WEST AND THEN NORTHWEST. THE RAP BUFKIT SOUNDING ALSO NOW SHOWS
LITTLE POTENTIAL FOR SATURATION TO OCCUR BEHIND THE BOUNDARY
MAKING IT LOOK LESS LIKELY THAT FOG AND LOW LEVEL STRATUS WILL
FORM. GIVEN THAT BOTH SITES DID HAVE RAIN TONIGHT...WILL LEAVE
SOME MVFR VISIBILITIES IN THE FORECASTS IN THE EVENT THAT THE
WINDS DROP OFF SOME BEHIND THE FRONT. WITH ALL THE LOW LEVEL
MOISTURE FROM THE RAIN AND AS SOME HEATING STARTS AFTER
SUNRISE...DO EXPECT TO SEE SOME MVFR CEILINGS FORM BY MID MORNING
AND THE PERSIST INTO THE EARLY AFTERNOON BEFORE THESE LIFT TO VFR.
THESE CEILINGS SHOULD THEN REMAIN THROUGH THE AFTERNOON BEFORE
SCATTERING OUT LATE IN THE AFTERNOON OR EARLY EVENING.
&&
.HYDROLOGY...
ISSUED AT 315 PM CDT MON AUG 18 2014
SO FAR IN AUGUST...OVERALL IT HAS BEEN QUITE DRY WITH MUCH OF THE
AREA ADDED TO THE ABNORMALLY DRY CATEGORY PER THE DROUGHT MONITOR.
BUT AS WE SAW LAST NIGHT...SLOW MOVING STORMS PRODUCING TORRENTIAL
DOWNPOURS CAN RESULT IN SOME LOCALIZED FLOODING ISSUES. ONCE AGAIN
TONIGHT...WARM CLOUD DEPTH AND ELEVATED PRECIPITABLE WATER
AMOUNTS POINT TO HEAVY RAINFALL POTENTIAL. THIS TREND LOOKS TO
CONTINUE THROUGH MUCH OF THE WEEK AS WELL. DRY CONDITIONS
INITIALLY WILL ALLOW FOR MUCH OF THIS WATER TO BE UTILIZED BY THE
SOIL AND REPLENISHING STORAGE AREAS. BUT WE WILL HAVE TO MONITOR
THE RAINFALL OVER THE COMING DAYS AND PERHAPS CONSIDER THE NEED
FOR A FLOOD WATCH FOR AREAS THAT SEE REPEATED RAINFALL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...MW
LONG TERM...MW
AVIATION...04
HYDROLOGY...MW
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
858 PM MDT WED AUG 20 2014
.UPDATE...
ISSUED AT 846 PM MDT WED AUG 20 2014
MIDLVL MOISTURE PLUME CONTINUES TO STREAM NORTHWARD ACROSS THE CWA
THIS EVE PER LATEST WATER VAPOR SAT. THIS HAS ALLOWED SHOWERS AND
TSTMS TO PERSIST ACROSS PARTS OF THE AREA WELL INTO THE EVE. KCYS
RADAR LOOP SHOWS TWO SEPARATE AREAS OF PCPN LIKELY IN ASSOCIATION
WITH TWO DISTINCT SHORTWAVES EMANATING FROM THE UPPER LOW SPINNING
OVER SOUTHERN CA. THESE AREAS ARE THE HIGHER TERRAIN OUT WEST OVER
CARBON AND ALBANY COUNTIES...AND AREAS EAST OF I25 ALONG THE I80
CORRIDOR ACROSS WESTERN NE. HRRR TRENDS HAVE HINTED AT CONVECTION
CONTINUING BEYOND 06Z OVER THE SOUTHERN PANHANDLE. ADDED POPS THRU
06Z WITH GOOD MOISTURE IN PLACE...BUT SHOWERS SHOULD BE DECREASING
IN COVERAGE BY THEN. THE REST OF THE INHERITED FCST IS IN GOOD
SHAPE THIS EVE.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 330 PM MDT WED AUG 20 2014
CURRENT KCYS RADAR LOOP SHOWS SHOWERS AND FEW THUNDER SHOWERS
DEVELOPING OVER THE MOUNTAINS AND THE CHEYENNE RIDGE THIS
AFTERNOON...AND SLOWLY MOVING EASTWARD. ACTIVITY HAS BEEN WEAK
WITH ONLY A FEW ISOLATED LIGHTNING STRIKES. EXPECT THIS ACTIVITY
TO CONTINUE THROUGH INTO LATE THIS AFTERNOON AND EARLY THIS
EVENING WHILE DEVELOPING FURTHER EAST INTO THE HIGH PLAINS OF
SOUTHEAST WYOMING. EXPECT ANY THUNDERSTORMS TO QUICKLY DIMINISH
AROUND SUNSET.
THUNDERSTORM COVERAGE WILL LIKELY BE LOWER ON THURSDAY ACROSS MOST
OF THE FORECAST AREA AS WARMER AIR ALOFT MOVES INTO THE AREA AND
500MB HEIGHTS INCREASE THROUGH THE DAY. A COLD FRONT BOUNDARY WILL
BECOME MORE NOTICEABLE FURTHER NORTH ACROSS MONTANA AND NORTHERN
WYOMING AS IT SLOWLY DRIFTS SOUTHWARD THROUGH THE DAY.
THEREFORE...EXPECT THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS
TO BE ACROSS THE MOUNTAINS AND WELL NORTH OF I80. CAN NOT RULE OUT
A THUNDER SHOWER OR TWO ALONG THE I80 CORRIDOR DURING THE EVENING
HOURS. TEMPERATURES WILL REMAIN NEAR NORMAL AND GENERALLY IN THE
UPPER 70S WEST OF THE LARAMIE RANGE AND LOW 80S TO LOW 90S ACROSS
THE EASTERN PLAINS.
THIS PERSISTENT WEATHER PATTERN WILL BEGIN TO CHANGE ON FRIDAY AND
ESPECIALLY THIS WEEKEND. MODELS INDICATE A PRETTY STRONG COLD
FRONT FOR THIS TIME OF THE YEAR PUSHING SOUTHWARD INTO SOUTHEAST
WYOMING. THIS FRONT WILL STALL SOMETIME ON FRIDAY AND BE THE MAIN
FOCUS FOR SCATTERED TO NUMEROUS SHOWERS AND TSTORMS AS AN UPPER
LEVEL TROUGH FROM WESTERN CANADA MOVE SOUTH AND EVENTUALLY
EASTWARD INTO IDAHO. LOWERED MAX AND MIN TEMPERATURES FRIDAY AND
FRIDAY NIGHT AND INCREASED POP BETWEEN 25 TO 45 PERCENT ACROSS THE
HIGH PLAINS...AND NEAR 70 PERCENT OVER THE MOUNTAINS.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 330 PM MDT WED AUG 20 2014
BOTH THE GFS AND ECMWF BRING A SHORTWAVE THROUGH THE AREA IN
SOUTHWEST WIND FLOW FRIDAY NIGHT INTO SATURDAY. ECMWF ROUGHLY 12
HOURS SLOWER THAN THE GFS...BUT BOTH ARE IN CLOSE AGREEMENT WITH
MOVEMENT OF FIRST DISTURBANCE...THEN MOVING THE MAIN TROUGH
THROUGH ON SATURDAY/SATURDAY NIGHT. JUST ABOUT EVERYONE SHOULD SEE
SHOWERS/THUNDERSTORMS DURING THE DAY SATURDAY WITH BEST CHANCES
FOR THE PANHANDLE SATURDAY NIGHT. MAIN SHORTWAVE THROUGH THE AREA
BY SUNDAY...WITH MAINLY ISOLATED SHOWERS OVER THE MOUNTAINS.
NEXT COLD FRONT LOOKS TO MOVE INTO THE AREA MONDAY AFTERNOON INTO
TUESDAY. ECMWF A LITTLE COLDER THAN GFS IN 700MB
TEMPERATURES...BUT NOT AS BAD AS A FEW DAYS AGO. PROBABLY NEED TO
GO COLDER WITH THIS SETUP. DISCREPANCY MUCH GREATER ON TUESDAY
WITH THE ECMWF FORECASTING 700MB TEMPERATURES OF +4 TO +6C AND GFS
SHOWING +10 TO +12C.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY AFTERNOON)
ISSUED AT 539 PM MDT WED AUG 20 2014
ISOLATED SHOWERS AND THUNDERSTORMS WILL DIE OFF THIS
EVENING BY AROUND 04Z. GUSTY WINDS AND SMALL HAIL POSSIBLE WITH
THUNDERSTORMS. OUTSIDE OF THUNDERSTORM ACTIVITY THIS EVENING WINDS
WILL BE LIGHT ACROSS SOUTHEAST WY AND NEBRASKA PANHANDLE TONIGHT.
WINDS WILL GENERALLY REMAIN LIGHT THROUGH THURSDAY BUT SOME GUSTS
TO 25 MPH CAN BE EXPECTED THURSDAY AFTERNOON ALONG AND WEST OF THE
LARAMIE RANGE. A FEW THUNDERSTORMS WILL BE POSSIBLE THURSDAY
AFTERNOON AND EARLY EVENING.
&&
.FIRE WEATHER...
ISSUED AT 156 PM MDT WED AUG 20 2014
MINIMAL FIRE WEATHER CONCERNS INTO EARLY NEXT WEEK. SUBTROPICAL
MOISTURE WILL REMAIN OVER THE AREA THROUGH THE WEEKEND WITH
SHOWERS AND THUNDERSTORMS POSSIBLE EACH DAY ACROSS SOUTHEAST
WYOMING AND WESTERN NEBRASKA. THERE IS A GOOD CHANCE OF WETTING
RAINS BY FRIDAY AND THIS WEEKEND AS THUNDERSTORM COVERAGE WILL BE
HIGHER. TEMPERATURES WILL TREND COOLER BY LATE THIS WEEK AND INTO
THIS WEEKEND AS A STRONG COLD FRONT FOR THIS TIME OF THE YEAR
MOVES INTO THE REGION LATE ON SATURDAY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...HAMMER
SHORT TERM...TJT
LONG TERM...CLAYCOMB
AVIATION...SML
FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
250 PM MDT TUE AUG 19 2014
.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 250 PM MDT TUE AUG 19 2014
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS WHERE THE
CONVECTION WILL BREAK OUT THIS AFTERNOON AND HOW MUCH CONVECTION
WILL BREAK OUT AHEAD OF THE JET STREAK MOVING ACROSS THE ROCKIES
TONIGHT.
LATEST VISIBLE IMAGERY WAS SHOWING SOME ACCAS DEVELOPING ACROSS NORTHEAST
COLORADO NEAR THE SURFACE TROF. THIS AREA MAY END UP BEING THE
FIRST AREA TO FIRE UP THIS AFTERNOON. HOWEVER...IT MAY TRY TO
IGNITE JUST EAST OF THE LARAMIE AND FRONT RANGES AS WELL WHERE WE
HAVE HAD QUITE A BIT OF SUNSHINE. IN FACT...WE ARE STARTING TO SEE
A LITTLE BIT OF ACCAS OVERHEAD AND CONVECTION DEVELOPING ALONG THE
FRONT RANGE. MODELS ARE PROJECTING MIXED LAYER CAPES TO APPROACH 1500
J/KG THIS AFTERNOON WITH VERY LIMITED CAP. 0-6KM SHEAR VALUES
(~30KTS) MAY ALSO BE FAVORABLE FOR A FEW STRONG TO SEVERE STORMS.
AT THIS POINT...IT LOOKS THE HRRR IS STARTING TO BREAK OUT
CONVECTION JUST EAST OF CHEYENNE AFTER 21Z WITH THE BULK OF THIS
CONVECTION PUSHING GENERALLY EAST AT AROUND 20KTS. A FEW OF THESE
STORMS MAY HAVE THE POTENTIAL TO PRODUCING STRONG WINDS AND HAIL IN THE
PANHANDLE THIS AFTERNOON. LATEST SURFACE ANALYSIS WAS ALSO SHOWING
SOME WINDS BACKING TO THE SOUTHEAST IN THE PANHANDLE. WE WILL ALSO
NEED TO WATCH THAT AS THE AFTERNOON WEARS ON...ESPECIALLY IF THE
STORMS GET GOING IN THAT REGION.
ANOTHER CONCERN IS THE NAM IS SHOWING A 500MB JET STREAK MOVING
OUT OF NORTHEAST COLORADO EARLY THIS EVENING WHICH MAY HELP
ENHANCE THE SHEAR ACROSS THE PANHANDLE. IF CONVECTION IS ON GOING
IN THAT REGION AS THIS JET STREAK MOVES ACROSS WE MAY HAVE MORE OF
A SEVERE POTENTIAL. THEREFORE...IT WILL BE A MATTER OF TIMING ON
HOW THINGS COME TOGETHER LATE THIS AFTERNOON AND EVENING.
TONIGHT THE MODELS ARE SHOWING A FAIRLY STRONG UPPER LEVEL JET
MOVING THROUGH NORTHERN COLORADO AND LIFTING NORTHEAST INTO
NORTHEAST WYOMING BY DAYBREAK WHICH WILL HELP ENHANCE UPPER LEVEL
DIFFLUENCE. THE MODELS ARE EVEN IN FAIRLY GOOD AGREEMENT IN
SHOWING A MID LEVEL CIRCULATION WITH THIS JET STREAK. AS A
RESULT... WE WOULD NOT SURPRISED TO SEE A COMPLEX OF SHOWERS AND
THUNDERSTORMS DEVELOP ACROSS THE WESTERN HALF OF THE FORECAST AREA
OVERNIGHT ALONG WITH THE POTENTIAL FOR HEAVY RAINFALL DUE TO PRECIPITABLE
WATER VALUES AROUND 1 INCH. NOT EXPECTING MUCH IN THE WAY OF
FLOODING SINCE THIS COMPLEX SHOULD BE FAIRLY PROGRESSIVE. WE DID
BUMP UP POPS ACROSS THE NORTHERN HALF OF THE AREA TONIGHT TO
REFLECT THIS POTENTIAL.
WEDNESDAY-THURSDAY NIGHT:
THE MID LEVEL CIRCULATION IS PROGGED TO CONTINUE LIFTING NORTHEAST
WHICH WILL TAKE THE BULK OF THE CONVECTION NORTHEAST OF THE
FORECAST AREA BY MID MORNING. THIS WILL LEAVE A FAIRLY BROAD AREA OF
SUBSIDENCE IN THE MORNING IN THE WAKE OF THE CONVECTION...BUT WE
MAY MORE CONVECTION DEVELOP IN THE AFTERNOON ACROSS THE MOUNTAINS
AS UPSLOPE FLOW COMMENCES WITH LEFTOVER RESIDUAL MOISTURE.
OTHERWISE...THE REMAINDER OF THE AREA EAST OF THE LARAMIE RANGE
SHOULD REMAIN FAIRLY DRY WITH HIGHS GENERALLY IN THE 80S. THE
NEXT CHANCE OF SHOWERS AND THUNDERSTORMS IS PROGGED TO TAKE PLACE
ON THURSDAY AFTERNOON AS ANOTHER UPPER LEVEL WAVE LIFTS NORTHEAST
OUT OF COLORADO AND PUSHES THROUGH AREAS EAST OF THE LARAMIE RANGE
THURSDAY AFTERNOON INTO THURSDAY NIGHT.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 250 PM MDT TUE AUG 19 2014
AN UPPER LOW AND ASSOCIATED TROUGH OVER THE PACIFIC NW FRIDAY WILL
MOVE SLOWLY EAST TOWARDS THE AREA FRIDAY THROUGH SATURDAY...
SWINGING BY THE AREA ON SUNDAY. THIS WILL COMBINE WITH AT LEAST
RESIDUAL MONSOONAL MOISTURE TO KEEP CHANCES FOR SHOWERS AND TSTMS
GOING OVER MOST AREAS THROUGH SATURDAY NIGHT. WILL CONTINUE TO
LEAN TOWARDS THE EC SOLUTION AS IT HAS BEEN FAIRLY CONSISTENT WITH
THIS FEATURE. WARM TEMPS WILL CONTINUE THROUGH SATURDAY THEN A
DECENT COOL FRONT WILL PASS ACROSS SAT NIGHT LEAVING A DRIER AND
MILD DAY FOR THE CWA SUNDAY. CONTINUED MILD ON MONDAY WITH THE CWA
ON THE SOUTHERN PORTION OF BROAD CYCLONIC UPPER FLOW THAT WILL BE
OVER THE NORTHERN PART OF THE COUNTRY. A SECOND UPPER SHORTWAVE
SHOULD PASS BY TUESDAY BRINGING A REINFORCING SHOT OF COOLER AIR
AND A CHANCE FOR SOME PRECIPITATION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1123 AM MDT TUE AUG 19 2014
MID/HIGH CLOUDS WILL SPREAD ACROSS THE AREA THIS AFTERNOON AS A
SURGE OF MONSOONAL MOISTURE MOVES IN FROM THE SW. WDLY SCTD SHWRS
AND TSTMS DEVELOPING THIS AFTERNOON OVER AND NR THE SE WY MTNS WITH SOME
SHOWERS CONTINUING TONIGHT MAINLY OVER WESTERN TERMINALS. BRIEF MVFR
CIGS WITH ANY ACTIVITY.
&&
.FIRE WEATHER...
ISSUED AT 1056 AM MDT TUE AUG 19 2014
FIRE WEATHER CONCERNS TO REMAIN MINIMAL FOR THE REST OF THE WEEK
WITH NON-CRITICAL WEATHER CONDITIONS EXPECTED. SOME WETTING RAINS
SHOULD OCCUR OVER AT LEAST PARTS OF THE AREA OVER THE NEXT COUPLE
DAYS AS A SURGE OF MONSOONAL MOISTURE PASSES OVER THE REGION AND
INCREASES PRECIPITATION.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...REC
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...RE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1104 PM MDT WED AUG 20 2014
.UPDATE...
ISSUED AT 636 PM MDT WED AUG 20 2014
UPDATED FORECAST TO ADJUST FOR NR TERM TRENDS. LOOKS LIKE A FEW
ISOLD SHOWERS/TS COULD HANG ON OVER THE MTS AND ERN PLAINS THIS
EVE...BUT TREND IS DOWNWARD AND COVERAGE WILL BE MINIMAL SO HAVE
DROPPED MOST OF THE POPS BELOW 10 PERCENT FOR TONIGHT. ROSE
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 238 PM MDT WED AUG 20 2014
UPR LEVEL LOW IS SITTING ALONG THE SRN CA COAST TODAY AND IS
EXPECTED TO MOVE LITTLE IN THE NEXT 24 HOURS. WV SATELLITE IMAGES
SHOWING DRIER AIR HAS WORKED IT WAY INTO WRN CO TODAY. HRRR AND RAP
SHOWING MAINLY ISOLD PCPN COVERAGE THIS EVENING OVER WESTERN
PORTIONS OF THE FORECAST AREA...WITH ISOLATED TO SCT COVERAGE OVR
THE ERN MTS AND SERN PLAINS. A WEAK BOUNDARY IS FORECAST TO MOVE
INTO THE PALMER DVD AREA EARLY THIS EVENING AND THEN WORK ITS WAY
SOUTH. THIS BOUNDARY MAY HELP KICK OFF ADDITIONAL CONVECTION. THERE
COULD BE A FEW LINGERING SHOWERS OR TSTMS OVR THE SERN PLAINS...BUT
THINK THAT MOST OF THE PCPN SHOULD END BY 06Z.
ON THU...IT DOES NOT LOOK ALL THAT MOIST OVR THE FORECAST AREA.
PRECIPITABLE WATER VALUES OVR WRN AREAS ARE FORECAST TO BE SIMILAR
TO TODAY...WITH DRIER CONDITIONS OVR ERN AREAS. AS A RESULT THE
FORECAST MODELS SHOW MAINLY ISOLD TO SCT POPS OVR THE MTNS IN THE
AFTERNOON HOURS...WITH POSSIBLY A FEW STORMS OVR THE LOWER
ELEVATIONS. HIGH TEMPS FOR THU SHOULD BE AROUND AVERAGE IN THE HIGH
VALLEYS...WITH SLIGHTLY ABOVE NORMAL READINGS OVR THE SERN PLAINS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 238 PM MDT WED AUG 20 2014
NOT MUCH CHANGE TO THE FORECAST THINKING WITH THE GFS COMING INTO
LINE WITH THE ECMWF AND NAM SOLUTIONS. ENSEMBLES ARE STILL
DISPLAYING QUITE A BIT OF SPREAD BY EARLY NEXT WEEK...BUT
CONFIDENCE IS A HIGHER THAN IT WAS YESTERDAY IN A FORECAST
SOLUTION.
AN UPPER LEVEL DISTURBANCE OVER SOUTHERN CALIFORNIA IS FORECAST TO
EJECT NORTHEAST ACROSS COLORADO ON FRIDAY. EXPECT A FEW SHOWERS
AND THUNDERSTORMS TO BE ONGOING THURSDAY EVENING AND DISSIPATING
THROUGH MIDNIGHT OVER THE MOUNTAINS...WITH PERHAPS A FEW LINGERING
SHOWERS OVER THE PALMER DIVIDE INTO NORTHEAST COLORADO INTO EARLY
FRIDAY MORNING.
FRIDAY HAS THE POTENTIAL TO BE INTERESTING. THE UPPER DISTURBANCE
OVER ARIZONA WILL EJECT ACROSS COLORADO THROUGH FRIDAY EVENING.
MODELS QUICK TO ADVECT MOISTURE NORTH ACROSS COLORADO...AND SHEAR
LOOKS TO INCREASE TO AROUND 30 KTS OR SO BY THE AFTERNOON WITH
MODEST INSTABILITY. EXPECT SHOWER AND THUNDERSTORM DEVELOPMENT BY
MID MORNING FRIDAY ALONG THE CONTINENTAL DIVIDE...AND SPREADING
EAST INTO THE I-25 CORRIDOR BY EARLY IN THE AFTERNOON. MODEL QPF
FIELDS ARE INDICATING THAT HEAVY RAINFALL WILL BE
POSSIBLE...ESPECIALLY OVER THE MOUNTAINS AND LOCATIONS OVER THE
PALMER DIVIDE. FLASH FLOODING WILL BE POSSIBLE ON AREA BURN SCARS
AND FLOOD PRONE AREAS FRIDAY AFTERNOON AND EVENING. SOME STORMS
ACROSS THE PLAINS COULD BECOME STRONG...WITH SMALL HAIL AND GUSTY
OUTFLOW WINDS ALSO POSSIBLE. MODELS IN GOOD AGREEMENT WITH
THUNDERSTORMS SHIFTING EAST ACROSS THE PLAINS FRIDAY NIGHT WITH
ALL ACTIVITY EXITING INTO KANSAS BY SATURDAY MORNING.
SATURDAY WILL LIKELY BE A PRETTY QUIET DAY ACROSS SOUTHERN
COLORADO GIVEN SUBSIDENCE BEHIND THE DEPARTING UPPER SYSTEM. A
COUPLE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL
REMAIN POSSIBLE OVER THE MOUNTAINS...BUT COVERAGE LOOKS TO BE
MINIMAL.
A BROAD TROUGH WILL PERSIST OVER THE WESTERN CONUS THROUGH THE
MIDDLE OF NEXT WEEK WITH A COUPLE OF MORE DISTURBANCES MOVING
ACROSS SOUTHERN COLORADO. THE NEXT ONE LOOKS TO MOVE ACROSS THE
REGION ON SUNDAY. THIS WILL BRING ANOTHER UPTICK IN SHOWER AND
THUNDERSTORM ACTIVITY ACROSS THE STATE...WITH ACTIVITY STARTING
OVER THE MOUNTAINS LATE SUNDAY MORNING AND SPREADING EAST THROUGH
THE AFTERNOON AND EVENING. IN ADDITION...A COLD FRONT WILL MOVE
SOUTH ACROSS THE PLAINS DURING THE AFTERNOON...TURNING LOW LEVEL
FLOW UPSLOPE...WHICH WILL LIKELY AID PRECIPITATION DEVELOPMENT
ACROSS THE PLAINS SUNDAY AFTERNOON AND EVENING.
MODELS A BIT DIFFERENT ON THE ARRIVAL OF THE NEXT DISTURBANCE
DROPPING ACROSS THE ROCKIES...WITH GFS HAS BEEN BRINGING IT
THROUGH MONDAY EVENING...WITH THE ECMWF IS A BIT SLOWER ON
TUESDAY. THIS WILL LIKELY LEAD TO ANOTHER ROUND OF DECENT
PRECIPITATION FOR THE MOUNTAINS...AND SPREADING EAST INTO THE
PLAINS SOMETIME IN THE MONDAY TO TUESDAY TIME FRAME. THIS SYSTEM
LOOKS TO BE ACCOMPANIED BY A STRONG COLD FRONT WHICH SHOULD HELP
THE PLAINS SEE ANOTHER SHOT FOR PRECIPITATION. MOZLEY
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1049 PM MDT WED AUG 20 2014
...SIGNIFICANT IMPACT POSSIBLE ON FRIDAY...
ISOLATED STORMS WILL DEVELOP OVER THE MOUNTAINS THURSDAY
AFTERNOON. STORMS WILL BECOME MORE NUMEROUS AFTER 00Z AS
A LOW PRESSURE SYSTEM MOVES INTO COLORADO. ISOLD-SCT STORMS
WILL BE POSSIBLE THROUGH THU NIGHT...BUT THE MAIN AVN CONCERN
WILL COME ON FRIDAY AS THE UPPER LEVEL STORM SYSTEM MOVES
THROUGH. WIDESPREAD PRECIP AND STORMS WITH THE POTENTIAL FOR
HEAVY RAIN AND PERSISTENT MVFR-IFR CIGS WILL BE POSSIBLE FROM
FRI 15-18Z ON THROUGH FRI EVENING AND POSSIBLY INTO SAT
MORNING...ESPECIALLY EAST OF THE SANGRES AND RAMPARTS. ROSE
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ROSE
SHORT TERM...28
LONG TERM...MOZLEY
AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS TAUNTON MA
140 AM EDT THU AUG 21 2014
.SYNOPSIS...
WET WEATHER LIKELY IMPACTING WESTERN AND CENTRAL PORTIONS OF NEW
ENGLAND BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. DRIER AND
COOLER WEATHER FOLLOWS INTO THE WEEKEND. A WARM-UP IS POSSIBLE
INTO NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL
BOUNDARY SWEEPING SOUTH OUT OF CANADA.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
130 AM UPDATE...
MOST FORECAST PARAMETERS ON TRACK. ALTHOUGH SOME RAIN IS JUST
BEGINNING TO BREAK THE WRN MOST BORDER OF BOX CWA. INCREASED POPS
IN THIS REGION BY JUST A BIT.
PREVIOUS DISCUSSION...
PREVIOUS DISCUSSION...
HEIGHTS FALL AS THE GREAT LAKES LOW SHIFTS INTO THE NE CONUS...
TROUGHING TOWARDS THE W-E AXIS OF LOW PRESSURE AND INSTABILITY OFF
THE MID-ATLANTIC. LABRADOR RIDGE OF HIGH PRESSURE ALONG WITH DRY
AIR AND SUBSIDENCE WILL PERSIST INTO NEW ENGLAND...AHEAD OF WHICH
THE COLLISION TOWARDS LOW PRESSURE AND HIGHER THETA-E AIR WILL
RESULT IN A DEFINED AREA OF CONVERGENCE ACROSS PA/NY...AND
POSSIBLY SE MA.
TO THE W...INCREASING THETA-E MOISTURE LOADING THE MID- TO UPPER-
LEVELS WILL LIKELY RESULT IN INCREASING AND THICKENING CLOUDS W TO
E. BUT STILL A LOT OF DRY AIR TO OVERCOME BELOW H6-7 ESPECIALLY OVER
E NEW ENGLAND WITH THE INVERTED RIDGE. NOTING THE WARM FRONT WELL W
ACROSS PA/NY ALONG WITH PARENT DYNAMICS AND LOW-LEVEL CONVERGENCE...
BEST CHANCES FOR SHOWERS WITHIN AREAS OF DEEP-LAYER ASCENT SHOULD
BE NO FURTHER E OF THE CT-RIVER VALLEY. EXPECTING SPRINKLES. ITS
LIKELY BETTER ACTIVITY WILL BE WELL N/W PARENT WITH BETTER MOISTURE
CONVERGENT ALONG THE NOSE OF THE H925-85 JET INTO THE ADIRONDACKS
ON UP INTO ONTARIO/QUEBEC AS DESTABILIZATION CONCLUDES. PREFER
CHANCE POPS ONLY INTO THE CT-VALLEY.
TO THE SE...TROUGHING SE BACKS LOW PRESSURE AND HIGHER THETA-E AIR
OFF THE E-W STALLED FRONT OFF THE MID-ATLANTIC. THE CONVERGENCE OF
AIR MASSES ALONG AN INVERTED-TROUGH TO THE AFOREMENTIONED LOW WILL
BE THE FOCUS FOR POTENTIAL HEAVY RAIN...EVEN THUNDERSTORMS. MAINLY A
WARM-RAIN PROCESS WITH PWATS UP TO 1.75 INCHES. WHILE A CONSISTENT
SIGNAL AMONG FORECAST SOLUTIONS...OUTCOMES VARY SLIGHTLY LIKELY DUE
TO THE STRENGTH OF INVERTED-RIDGE. WILL GO WITH LIKELY POPS FOR
NANTUCKET WITH CHANCE POPS INTO THE CAPE AND SE MA. THE SETUP IS
ALREADY COMING TOGETHER SEEN PER IR/VISIBLE SATELLITE...BUT A LOT
OF UNCERTAINTY BETWEEN THE STRENGTH OF THE RIDGE AND THE ZONE
SETUP OF CONVERGENCE. WRF/NAM THE MOST ROBUST WITH OUTCOMES. 17Z
HRRR/18Z RAP HAS ACTIVITY MISSING NANTUCKET. NOT ENOUGH CONFIDENCE
TO GO HIGH CATEGORICAL POPS.
THICKER CLOUDS ACROSS THE REGION WILL LIMIT RADIATIONAL COOLING.
ANTICIPATING A MORE MILD NIGHT OVER MUCH OF THE REGION WITH LOWS
AROUND THE UPPER-50S. COOLEST CONDITIONS EXPECTED ACROSS E/SE MA
UNDER LIGHT AND VARIABLE WINDS AND THE BETTER CHANCE OF RADIATING
OUT...LOWS AROUND THE MID-50S. FOR SUCH AREAS THERE IS ALSO THE
POSSIBILITY OF PATCHY GROUND FOG.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
THURSDAY INTO THURSDAY NIGHT...
CLOSED LOW OUT OF THE GREAT LAKES GRADUALLY WOBBLES INTO NEW ENGLAND
THROUGH THE FORECAST PERIOD. THE SYSTEM WEAKENS AS IT TRANSITIONS SW
RE-EMERGING ALONG THE W-E FRONTAL BOUNDARY OFF THE MID-ATLANTIC
TOWARDS THE BETTER THERMAL-INSTABILITY AXIS.
SUBSEQUENT RISING HEIGHTS ALLOWS RIDGING TO BUILD SW THURSDAY
NIGHT. WHILE HIGHER THETA-E AIR STREAMS ACROSS THE REGION WITHIN
THE MID-LEVELS...E-FLOW WITHIN LOW-LEVELS FROM THE LABRADOR HIGH
UNDERCUTS MOISTURE LOADING ALOFT KEEPING CONDITIONS FAIRLY STABLE
AND DRY...LIKELY TO ERODE ACTIVITY S AND W.
AS THE LOW TRANSITIONS AND WEAKENS...PRECIPITATION ACROSS THE CAPE
AND ISLANDS CONCLUDES WITH THE STRENGTHENING INFLUENCE OF THE
RIDGE. ENERGY AND MOISTURE PARENT TO THE LOW IS ANTICIPATED TO
SWEEP MAINLY ACROSS SW NEW ENGLAND...PERHAPS SW OF A LINE FROM
BOSTON TO KEENE NH. WILL KEEP THESE AREAS UNDER CHANCE POPS
ACCORDINGLY WITH ASCENT AND LIKELY CONVERGENCE AGAINST THE SW
BUILDING RIDGE.
WITH THE UNDERCUTTING DRY AND STABLE AIRMASS OFF THE OCEAN WITH THE
STRENGTHENING RIDGE LATE...AND CLOUDS THROUGH THE PERIOD LIMITING
DESTABILIZATION...NOT EXPECTING ANY THUNDER. HIGHS AROUND THE MID-
TO UPPER-70S DURING THE DAY WITH LOWS AROUND THE UPPER-50S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGHLIGHTS...
* QUIET WEATHER EXPECTED THROUGH MUCH OF THE LONG TERM
* UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING
FRONT.
MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. A
PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE
ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL
RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN U.S. THE UPPER
TROUGH IS RATHER PERSISTENT THOUGH AND EACH MODEL RUN KEEPS THE
TROUGH JUST OFFSHORE LONGER AND LONGER.
COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN
QUEBEC WILL KEEP THINGS RELATIVELY DRY. MODELS ARE INDICATING SOME
POTENTIAL FOR QPF EACH DAY THROUGH THE WEEKEND BUT GIVEN THE LACK OF
ANY FORCING MECHANISM AND VERY LITTLE MOISTURE TO SPEAK OF...
THINKING THIS COULD BE CONVECTIVE FEEDBACK RATHER THAN A DEPICTION
OF ANYTHING LIKELY TO OCCUR.
THE HIGH WILL SINK SOUTH THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...EVENTUALLY DROPPING SOUTH AND EAST OF SOUTHERN NEW ENGLAND
AND RETURNING US TO A MORE WESTERLY FLOW. LOW PRESSURE IN ONTARIO
MAY EVENTUALLY MOVE EASTWARD INTO QUEBEC BRINGING A COLD FRONT
THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE
MODELS START TO DIVERGE A BIT WITH THE ECMWF A BIT QUICKER THAN THE
GFS WITH THE APPROACH OF THE FRONT. DEPENDING ON AVAILABLE MOISTURE
THIS MAY INITIATE A FEW SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM...THROUGH FRIDAY...MODERATE CONFIDENCE.
THROUGH 12Z...
MAINLY VFR EXCEPT SOME IFR/MVFR POSSIBLE AT SOME SITES ACROSS E
MA IN FOG. SOME MVFR CIGS POSSIBLE MAINLY ACROSS ACK AND THE OUTER
ARM OF CAPE COD.
TODAY AND TONIGHT...
MAINLY VFR. EXCEPT FOR ACK...MOST OF THE RAIN REMAINS TO THE W
THROUGH THE DAY. THEN...BETTER CHANCE FOR SHOWERS ACROSS WRN
MA/CT/NH OVERNIGHT ESPECIALLY...WITH OCCASIONAL MVFR CONDITIONS
POSSIBLE. SOME LOW MVFR/IFR POSSIBLE MAINLY ACROSS THE E COAST.
FRI...
CONDITIONS IMPROVE THROUGH THE DAY. SOME MVFR/IFR POSSIBLE IN THE
MORNING GIVES WAY TO VFR THROUGH THE DAY...BUT MAY TAKE MOST OF
THE DAY ALONG THE E COAST.
KBOS TERMINAL...MODERATE CONFIDENCE. MAIN CONCERN IS WHETHER A
BRIEF PERIOD OF IFR CONDITIONS MOVE IN EARLY THIS MORNING
BRIEFLY...AND THEN RETURNS LATE THU NIGHT. OTHERWISE VFR WITH E
FLOW ASSISTED BY SEABREEZES EXPECTED.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. -RA CHANCES BEGIN TOWARDS
THURSDAY MORNING ALONG WITH LOW-END VFR CIGS. MVFR CIGS POSSIBLE
THOUGH MAINLY TONIGHT...BUT REMAINS LOW-CONFIDENCE AT THIS TIME.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF PATCHY
MVFR/IFR FOG EACH NIGHT.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT-TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE.
CLOSELY MONITORING THE SE WATERS. MAY SEE A SURGANCE OF RAIN ALONG
WITH VISIBILITY IMPACTS DURING THE OVERNIGHT HOURS INTO THURSDAY
ALONG WITH AN INCREASE IN E-NE FLOW AS AN AREA OF LOW PRESSURE
DEVELOPS WELL OUT TO SEA. QUITE POSSIBLE WIND GUST UP TO 25
KTS...BUT WILL HOLD AROUND 20 KTS FOR NOW. WILL KEEP SEAS AROUND 3
TO 4 FEET. CONDITIONS RELAX INTO FRIDAY MORNING.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE TO HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED
THROUGH MUCH OF THE PERIOD WITH HIGH PRESSURE ACROSS THE REGION.
LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RLG/SIPPRELL
NEAR TERM...DOODY/SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...RLG
AVIATION...KJC/DOODY/RLG
MARINE...RLG/SIPPRELL
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
334 AM EDT THU AUG 21 2014
.SYNOPSIS...
THE REGION WILL SEE AN ACTIVE WEATHER PATTERN FOR THE NEXT TWO DAYS
AS ONE AREA OF HIGH PRESSURE REMAINS OVER THE DEEP SOUTH, WHILE
ANOTHER IS SITUATED OVER THE HUDSON BAY. THE CANADIAN HIGH WILL
EVENTUALLY BUILD SOUTH OVER THE REGION BY LATE THIS WEEKEND AND
REMAIN THE THE MAIN WEATHER FEATURE FOR THE MID ATLANTIC THROUGH MID
WEEK NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THERE ARE A COUPLE OF AREAS OF ISOLATED/SCATTERED SHOWERS AROUND THE
AREA EARLY THIS MORNING, ALL ASSOCIATED WITH A FEW INDIVIDUAL
VORTICITY IMPULSES MOVING THROUGH THE CYCLONIC FLOW ALOFT. THE FIRST
IS EXITING OUR AREA TO THE NORTHEAST, AND WILL BRING WITH IT IT`S
AREA OF SHOWERS. THE OTHERS ARE LOCATED ACROSS CENTRAL AND WESTERN
PENNSYLVANIA. THE HRRR AND RUC HAVE THESE DRIFTING EASTWARD AND
MOSTLY DRYING OUT OR LIFTING TO OUR NORTH BEFORE THEY GET HERE.
AFTER THESE SHOWERS EARLY THIS MORNING, WE SHOULD GET A PERIOD FROM
MID/LATE MORNING INTO THE EARLY AFTERNOON WHERE WE SHOULD BE MOSTLY
SHOWER FREE. HOWEVER, AS WE MOVE INTO THE MID TO LATE AFTERNOON, WE
EXPECT SHOWERS TO BEGIN TO INCREASE TO OUR WEST AND MOVE INTO OUR
AREA. THESE WILL BE ASSOCIATED WITH ANOTHER SHORT WAVE/VORTICITY
IMPULSE THAT WILL BE MOVING INTO OUR AREA AS THE MID/UPPER LOW
SLOWLY DRIFTS EASTWARD. AT THE SURFACE, AN AREA OF LOW PRESSURE
REMAINS ACROSS THE EASTERN GREAT LAKES, WHILE A WEAKENING FRONTAL
BOUNDARY EXTENDS SOUTH OF THE LOW. ANOTHER FRONTAL BOUNDARY REMAINS
SNAKED FROM WESTERN PENNSYLVANIA SOUTHWARD THROUGH VIRGINIA AND
NORTH CAROLINA. NONE OF THESE FEATURES ARE EXPECTED TO MOVE INTO THE
AREA TODAY AS THE LOW IS EXPECTED TO REMAIN TO OUR NORTH AND THE
FRONTAL BOUNDARY TO OUR SOUTH IS EXPECTED TO REMAIN STATIONARY
THROUGH THE DAY.
THERE REMAINS SOME INSTABILITY FORECAST TODAY, ALTHOUGH THERE IS
NOT MUCH SHEAR OR MUCH OF A WIND FIELD, SO WE DO NOT EXPECT SEVERE
WEATHER AT THIS TIME. IF THERE ARE ANY THUNDERSTORMS LATER TODAY,
AND IF THEY GROW TALL ENOUGH, SOME GUSTY WINDS COULD BE POSSIBLE AND
WITH THE WETBULB AS LOW AS IT IS, SOME SMALL HAIL CANNOT BE RULED
OUT. PW VALUES ARE GENERALLY FORECAST AROUND 1.5-1.75 INCHES, SO
SOME SHOWERS/STORMS COULD PRODUCE A PERIOD MODERATE TO HEAVY
RAINFALL.
FOR HIGHS, USED A BLEND OF MAV/MET MOS, MOSGUIDE, AND MIXED 925 MB
TEMPS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
WE EXPECT SHOWERS AND POSSIBLY THUNDERSTORMS TO BE ONGOING AT THE
START OF THE SHORT TERM PERIOD AS THE VORTICITY IMPULSE WILL BE
MOVING THROUGH THE AREA AS THE MID/UPPER LOW CONTINUES TO DRIFT
EASTWARD INTO NEW ENGLAND. ALSO, A SECOND AREA OF SURFACE LOW
PRESSURE IS FORECAST TO DEVELOP NEAR THE CHESAPEAKE BAY ALONG THE
STATIONARY BOUNDARY TO OUR SOUTH AS IT TRIES TO LIFT NORTHWARD INTO
OUR SOUTHERN AREAS. THIS MAY KEEP A FOCUS FOR PRECIPITATION
OVERNIGHT ACROSS OUR SOUTHERN AREAS WHERE SHOWERS MAY LAST INTO THE
EARLY MORNING HOURS OF FRIDAY. AS THE ENERGY FROM THE VORTICITY
IMPULSE MOVES AWAY FROM THE AREA, SHOWERS SHOULD MOSTLY END BY
DAYBREAK.
FOR LOWS, USED A BLEND OF MAV/MET MOS AND MOSGUIDE.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
FRIDAY THROUGH SATURDAY...THE REGION REMAINS UNDER NORTHWEST FLOW AS
THE STOUT RIDGE REMAINS OVER THE MISSISSIPPI VALLEY, AND THE OTHER
HIGH REMAINS OVER EASTERN CANADA. WITH THE NORTHWEST FLOW, EXPECT A
FEW EMBEDDED SHORT WAVE TROUGHS TO BRING CHANCES FOR THUNDERSTORMS
THROUGH THIS PERIOD. HOWEVER, THE TIMING OF THE INDIVIDUAL SHORT
WAVE TROUGHS REMAINS UNCERTAIN.
SUNDAY THROUGH THURSDAY...THE HIGH OVER EASTERN CANADA BUILDS SOUTH.
WITH THE ASSOCIATED COLD AIR ADVECTION, COULD SEE HIGHS ESPECIALLY
EARLY IN THE WEEKEND 5 TO 10 DEGREES BELOW NORMAL. BY TUESDAY
HOWEVER, THE HIGH STARTS TO SHIFT OFF SHORE, LEAVING THE REGION
UNDER SOUTHERLY FLOW AND LEADING TO A MODEST WARMING TREND. HOWEVER,
ALSO TOWARDS THE END OF THIS FORECAST PERIOD THE GFS AND ECMWF
SOLUTIONS DIFFER GREATLY ON THE TIMING OF AN UPPER LEVEL TROUGH AND
ASSOCIATED SURFACE COLD FRONT THAT WILL BE PROPAGATING EAST ON THE
HEALS OF THE HIGH. STILL, BOTH SOLUTIONS SHOW THESE FEATURES JUST
BEYOND THE SEVEN DAY FORECAST.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
OVERALL, WE EXPECT MOSTLY VFR CONDITIONS FOR THE TAF SITES TODAY,
ALTHOUGH THERE IS THE POTENTIAL FOR LOWER CONDITIONS LATER TODAY
INTO THIS EVENING. A PERIOD OF MVFR CIG AND/OR VSBY IS POSSIBLE
EARLY THIS MORNING MAINLY FOR ABE/RDG/MIV, BUT THIS SHOULD RETURN TO
VFR BY MID-MORNING.
WE EXPECT SCATTERED SHOWERS, AND POSSIBLY THUNDERSTORMS, TO DEVELOP
TO OUR WEST TROUGH THE DAY AND MOVE INTO OUR AREA LATER THIS
AFTERNOON INTO THIS EVENING AS A DISTURBANCE ALOFT MOVES THROUGH THE
AREA. CONFIDENCE IN THUNDERSTORM ACTIVITY OCCURRENCE AND TIMING IS
LOW, SO THEY WERE NOT INCLUDED IN THE TAFS AT THIS TIME.
THERE IS THE POTENTIAL FOR SOME MODERATE TO HEAVY SHOWERS, SO WE
HAVE INCLUDED MODERATE SHOWERS WITH MVFR CONDITIONS LATER TODAY INTO
THIS EVENING. ONE MODEL GIVES US VFR THROUGH THE PERIOD, WHILE THE
OTHER BRINGS EVERYONE TO IFR. NOT CONFIDENT ON IFR, BUT THINK WE
COULD GET SOME LOWER CONDITIONS TEMPORARILY WITH THE HEAVIER SHOWERS.
WINDS TODAY SHOULD BE MOSTLY SOUTH TO SOUTHEAST AROUND 5 TO 10 KNOTS.
OUTLOOK...
FRIDAY AND SATURDAY...MOSTLY VFR. ISOLATED TO SCATTERED TSRA ARE
POSSIBLE ACROSS THE REGION. UNDER ANY TSRA MVFR CEILINGS AND
BRIEF IFR VISIBILITIES WILL BE POSSIBLE.
SUNDAY THROUGH MONDAY...GENERALLY VFR.
&&
.MARINE...
SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED TODAY WITH SEAS 2-3
FEET OR LESS AND SOUTHEAST WINDS 5 TO 10 KNOTS.
OUTLOOK...
FRIDAY...CONDITIONS EXPECTED TO STAY BELOW SMALL CRAFT ADVISORY CRITERIA.
SATURDAY...OCCASIONAL GUSTS NEAR 25 KT AND WAVE HEIGHTS APPROACHING
5 FT ARE POSSIBLE ESPECIALLY SATURDAY AFTERNOON THROUGH SATURDAY
NIGHT.
SUNDAY AND MONDAY...WAVE HEIGHTS AND WINDS SLOWLY FALLING BELOW
SMALL CRAFT ADVISORY CRITERIA SUNDAY MORNING AND SHOULD REMAIN
BELOW CRITERIA THROUGH MONDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JOHNSON
NEAR TERM...ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...JOHNSON
AVIATION...JOHNSON/ROBERTSON
MARINE...JOHNSON/ROBERTSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
211 AM EDT THU AUG 21 2014
.SYNOPSIS...
DRIER AIR AND A BUILDING UPPER RIDGE JUST TO OUR WEST WILL REDUCE
THUNDERSTORM CHANCES THROUGH FRIDAY...AND LEAD TO HOTTER HIGH
TEMPERATURES. AN APPROACHING COLD FRONT AND INCREASING MOISTURE
WILL INCREASE THE THUNDERSTORM CHANCE OVER THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SCATTERED CONVECTION HAS ENDED ACROSS THE AREA THIS EVENING.
STILL SOME ACTIVITY WELL UPSTREAM OVER ERN TN AND NRN GA BUT AT
THIS TIME EXPECT THOSE STORMS TO STAY EITHER WELL WEST OF THE
FORECAST AREA OR DISSIPATE BEFORE REACHING OUR AREA GIVEN THE
LATEST HRRR CYCLE. NOCTURNAL COOLING WITH DRY AIR ALOFT AND LIGHT
WIND SHOULD HELP SUPPORT AREAS OF FOG TOWARD SUNRISE. OVERNIGHT
LOWS IN THE IN THE LOWER AND MIDDLE 70S STILL LOOK REASONABLE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
UPPER RIDGE WILL BUILD JUST TO OUR WEST. THIS AND A LOW LEVEL
DOWNSLOPE FLOW WILL LEAD TO WARMING TEMPS. MODELS CONTINUE TO
INDICATE MAX TEMPS NEAR 100 DEGREES MOST AREAS...AND CONTINUE TO
INDICATES DEW POINTS MIXING DOWN INTO THE MID TO UPPER 60S ACROSS
THE NORTHERN AND WESTERN COUNTIES TO NEAR 70 OR LOWER 70S ACROSS
THE SOUTHEAST MIDLANDS. THIS KEEPS HEAT INDICES JUST BELOW OUR
HEAT ADVISORY CRITERIA OF 110F. ONLY SLIGHT CHANCE OF
SHOWERS/TSTMS EXPECTED DUE TO BUILDING RIDGE ALOFT...AND FAIRLY
DRY LOW LEVEL AIR LEADING TO AND HIGH LEVELS OF FREE
CONVECTION/HIGH CONVECTIVE TEMPS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
UPPER RIDGE TO OUR WEST WITH UPPER TROUGH AND CLOSED LOW TO OUR
NE...PROVIDING A NW FLOW ALOFT FOR OUR FA. SOME TIMING
UNCERTAINTIES WITH A BACK DOOR FRONT. MODELS TRENDING A LITTLE
SLOWER WITH IT OF LATE...WITH POSSIBILITY THAT IT MAY NOT MAKE IT
TO OUR FA UNTIL SATURDAY AFTERNOON OR EVENING...SLOWLY PUSHING
SOUTH THROUGH SUNDAY. INCREASING POPS/THUNDER CHANCE ALONG AND
SOUTH OF THE BOUNDARY...WITH COOLER TEMPS NORTH OF IT. FRONT TO
PUSH TO OUR SOUTH EARLY NEXT WEEK...WITH SURFACE AND UPPER RIDGE
OVER THE EASTERN SEABOARD.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
EXPECT VFR CONDITIONS TO DOMINATE THE PERIOD...WITH EARLY MORNING
MVFR CONDITIONS AT AGS/OGB.
CIRRUS FROM UPSTREAM CONVECTION CONTINUES TO BLANKET THE AREA AND
WILL WORK TO LIMIT FOG DEVELOPMENT. WITH THE CLOUDS EXPECTED
THROUGH MUCH OF THE NIGHT HAVE DECREASED THE FOG THREAT AT
CAE/CUB/DNL TO A TEMPO GROUP WHILE MAINTAINING MVFR FOG AT
AGS/OGB. FOG WHICH DEVELOPS WILL QUICKLY ERODE WITH SUNRISE WITH
THE REMAINDER OF THE PERIOD VFR. CHANCES OF DIURNAL CONVECTION
REMAIN TOO LOW TO INCLUDE IN TAFS. WINDS THROUGH THE PERIOD WILL
BE WESTERLY AT 5 KNOTS OR LESS.
EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE
NIGHT AND EARLY MORNING FOG THROUGH THE PERIOD. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
135 AM CDT THU AUG 21 2014
.DISCUSSION...
819 PM CDT
FOR EVENING UPDATE...
HAVE MADE SOME FAIRLY SIGNIFICANT UPDATES TO SHOWER/THUNDERSTORM
POPS AND TIMING OVERNIGHT...BASED ON OBSERVATIONAL DATA AND HIGH
RES MODEL TRENDS OVER THE PAST SEVERAL HOURS. OVERALL...HAVE
TRIMMED BACK POPS TO ISOLATED/SCATTERED SHOWERS THROUGH THE
REMAINDER OF THIS EVENING...WITH GRADUAL INCREASE IN SCATTERED
SHOWER/THUNDERSTORM COVERAGE AFTER MIDNIGHT...BUT WITH GREATEST
POTENTIAL LOOKING LIKE THURSDAY MORNING WITH EXPECTED MCS REMNANTS
ARRIVING FROM MINNESOTA.
A STATIONARY FRONT STRETCHES FROM SOUTH DAKOTA SOUTHEAST ACROSS
NORTHERN MISSOURI AND INTO THE LOWER OHIO VALLEY THIS EVENING.
NORTH OF THE SURFACE BOUNDARY...AN AREA OF CLOUDS AND ISOLATED
SHOWERS HAS PERSISTED WITHIN THE ELEVATED BAROCLINIC ZONE...WITH A
COUPLE OF WEAK SHORT WAVES NOTED TOPPING MID-LEVEL SHORT WAVE
RIDGE AXIS WHICH WAS ROUGHLY FROM ST LOUIS NORTHWEST INTO
SOUTHWEST MINNESOTA. MODEL GUIDANCE HAS BEEN VERY INSISTENT IN
DEVELOPING STRONG CONVECTION ALONG THIS ELEVATED BAROCLINIC ZONE
THIS EVENING INTO EARLY THURSDAY MORNING...THOUGH COMPARISON TO
OBSERVED RADAR/SATELLITE DATA SUGGESTS GUIDANCE HAS BEEN OVER
FORECASTING EXTENSIVE COVERAGE OF DEEP CONVECTION SO FAR.
WITH THE BEST LOW LEVEL JET FLOW AND SHORT WAVE FORCING CURRENTLY
ACROSS THE PLAINS AND ORIENTED INTO THE MID-MISSOURI VALLEY
REGION...WOULD ANTICIPATE THE BEST AREA FOR STRONG CONVECTION TO
DEVELOP OVER THE NEXT FEW HOURS WOULD BE FROM NORTHEAST
NEBRASKA/SOUTHEAST SOUTH DAKOTA INTO WESTERN MINNESOTA/NORTHWEST
IOWA. WEAKER FORCING AND WEAKER WEST-SOUTHWEST LOW LEVEL FLOW INTO
BAROCLINIC ZONE EAST OF THE MISSISSIPPI...WHICH SUGGESTS LESS
INTENSIVE DEVELOPMENT HERE. DEVELOPMENT STILL EXPECTED ACROSS THE
AREA DURING THE NIGHT AS THE LOW LEVEL WEST-SOUTHWESTERLY FLOW
STRENGTHENS A BIT...THOUGH CONFIDENCE IS FAIRLY LOW ON AMOUNT OF
COVERAGE. HRRR HAS CONSISTENTLY SHOWN THE SCENARIO OF AN MCS
DEVELOPING OUT OF ANTICIPATED CONVECTION OVER THE PREVIOUSLY
MENTIONED MID-UPPER MISSOURI VALLEY REGION OVERNIGHT...WHICH WOULD
APPROACH THE FORECAST AREA FROM THE NORTHWEST TOWARD MORNING. WITH
ALL OF THIS IN MIND...HAVE TRIMMED BACK POPS OVERNIGHT AND
ESPECIALLY THIS EVENING...GRADUALLY INCREASING CHANCES AFTER
MIDNIGHT. MAINTAINED LIKELY POPS THURSDAY MORNING...WITH MCS
REMNANTS EXPECTED TO PERHAPS PRESENT THE GREATEST RAINFALL
PROBABILITY. 00Z SOUNDINGS UPSTREAM OF OUR FORECAST AREA DEPICT
PWATS IN THE 1.5-1.6 INCH RANGE SO STILL A LOCALLY HEAVY RAINFALL
THREAT FROM STRONGER CONVECTION ESPECIALLY DURING THE PRE-DAWN
THROUGH MID-MORNING THURSDAY PERIOD.
ALSO...WITH CLOUDS AND LIGHT WEST-SOUTHWEST FLOW BUMPED MIN TEMPS
JUST A BIT OVERNIGHT.
RATZER
//PREV DISCUSSION...
320 PM CDT
MAIN FORECAST CONCERNS ARE WITH PERSISTENT CHANCES FOR SHOWERS AND
THUNDERSTORMS OVER THE NEXT SEVERAL DAYS...WITH SOME POTENTIAL FOR
STRONG/SEVERE STORMS BUT WITH HIGHER CONFIDENCE FOR HEAVY
RAINFALL. WITH CONFIDENCE STILL LOWER ON COVERAGE AND PLACEMENT
OF STORMS TONIGHT...HAVE NOT ISSUED A FLOOD WATCH AT THIS TIME
BUT DID ISSUE AN SPS TO RAISE AWARENESS FOR THIS POTENTIAL.
IN THE NEAR TERM...QUIETER CONDITIONS ONGOING THIS AFTERNOON WITH
THE BULK OF THE CWA DRY. LATEST RADAR IMAGERY DEPICTING STEADY
STREAM OF SHOWERS AND THUNDERSTORMS STILL MOVING SOUTHEAST THROUGH
EASTERN IOWA AND WEST CENTRAL ILLINOIS...BUT WITH COVERAGE AND
INTENSITY DIMINISHING. SHORT TERM GUIDANCE STILL TRYING TO BRING
PRECIP ACROSS NORTH/NORTHEAST ILLINOIS LATE THIS AFTERNOON INTO
THE EARLY EVENING BUT DONT REALLY AGREE. FEEL THAT CONDITIONS WILL
REMAIN DRY THROUGH EARLY THIS EVENING FOR MOST LOCATIONS WITH THE
EXCEPTION FOR AREAS ALONG AND SOUTHWEST OF LINE FROM OREGON TO
WATSEKA...WHERE STEERING FLOW COULD DRIFT A STRAY SHOWER OR
THUNDERSTORM BRIEFLY OVER THAT AREA. ELSEWHERE...BRIEF AND LIGHT
RETURNS CONTINUE TO SHOW ON RADAR OVER NORTHEAST ILLINOIS IN AND
AROUND WEAK CONVERGENCE ALONG LAKE BREEZE IN FAR SOUTHEAST
WISCONSIN AND FAR NORTHEAST ILLINOIS. A LACK OF ANY INHIBITION
THIS AFTERNOON AND THIS WEAK CONVERGENCE COULD ALLOW FOR CONTINUED
DEVELOPMENT OF THESE LIGHT SHOWERS THIS AFTERNOON.
TONIGHT...INCREASING CHANCES FOR SHOWERS/THUNDERSTORMS WILL OCCUR
THROUGHOUT THE NIGHT AS UPSTREAM UPPER LEVEL RIDGE CONTINUES TO
BUILD ACROSS THE REGION WITH THE RIDGE AXIS SHIFTING EAST TOWARDS
THE CWA...AND WHILE SURFACE WARM FRONT SITUATED OVER THE SOUTHERN
CWA LIFTS NORTH. UPSTREAM SHORTWAVE ENERGY NOTED ON CURRENT WATER
VAPOR IMAGERY WILL RIDE ALONG THIS RIDGE AND MOVE ACROSS THE CWA
TONIGHT INTO EARLY THURSDAY MORNING. MEANWHILE...STRENGTHENING LLJ
WILL BEGIN VEERING THIS EVENING AND THEN BE ORIENTED TOWARDS THE
CWA LATER IN THE NIGHT. THIS WILL ALL PROVIDE FOCUS FOR
THUNDERSTORM DEVELOPMENT OVERNIGHT ESPECIALLY AS WAA RAMPS UP WITH
THE VEERING/STRENGTHENING LLJ. WEAK TO MODERATE INSTABILITY AXIS
WILL BE IN PLACE TONIGHT WITH POTENTIAL FOR SOME STEEPER MID LAPSE
RATES...CURRENTLY OBSERVED JUST SOUTH OF THE CWA...TO LINGER
TONIGHT. CONFIDENCE IS NOT OVERLY GREAT WITH REGARDS TO THE
INTENSITY OF STORMS TONIGHT BUT WITH THE PREVIOUSLY MENTIONED
FORCING MECHANISMS COMING TOGETHER OVERHEAD TONIGHT...WOULD EXPECT
THE POSSIBILITY FOR AT LEAST AN ISOLATED STRONGER STORM TO PROVIDE
A HAIL/WIND THREAT. FEEL THAT THE BEST CHANCES FOR THIS
POSSIBILITY COULD OCCUR OVER THE SOUTH/SOUTHWEST HALF OF THE
CWA...WHERE THE STEEPER MID LEVEL LAPSE RATES WILL POSSIBLY RESIDE
PER CURRENT ANALYSIS AND SREF GUIDANCE.
A GROWING CONCERN WILL BE FOR THE POTENTIAL OF HEAVY RAINFALL AND
LOCALIZED FLOODING WITH THESE STORMS TONIGHT INTO EARLY THURSDAY.
GUIDANCE CONTINUES TO VARY WITH REGARD TO OVERALL COVERAGE AND
EXACT PLACEMENT OF BEST DEVELOPMENT TONIGHT...AND WITH MY
CONFIDENCE NOT THE GREATEST WITH REGARDS TO RESIDENCE TIME OF ANY
STORM. NONETHELESS...OBSERVED HIGH PWAT AXIS OF 1.5 TO 2 INCHES
CURRENTLY OBSERVED JUST TO THE SOUTHWEST OF THE CWA WILL SHIFT
NORTHEAST OVER THE CWA TONIGHT...AND WITH THIS HIGHEST AXIS
EXPECTED TO BE CENTERED OVERHEAD TONIGHT. WITH THESE HIGH PWATS IN
PLACE AND WITH SURFACE DEWPOINTS AROUND 70 DEG AND 850MB DEWPOINTS
APPROACHING 15-16C...ANY STORM WILL EASILY HAVE THE POTENTIAL TO
PRODUCE HEAVY DOWNPOURS. DESPITE THESE CONCERNS...I ONCE AGAIN
DONT HAVE THE GREATEST CONFIDENCE OF COVERAGE/PLACEMENT AND HAVE
DECIDED TO HOLD OFF ON ANY FLOOD WATCH AT THIS TIME. THIS WILL
NEED TO CONTINUE TO BE CLOSELY MONITORED THIS EVENING BUT IN THE
NEAR TERM HAVE DECIDED TO ISSUE AN SPS FOR THIS POSSIBILITY. STILL
THINK THAT WHAT OCCURRED JUST TO THE WEST/SOUTHWEST TODAY COULD
EASILY OCCUR TONIGHT INTO THURSDAY OVER THE CWA...ALTHOUGH WITH
THE POSSIBILITY FOR A SLIGHTLY DIFFERENT SETUP PROVIDING
BETTER/STRONGER THUNDERSTORM DEVELOPMENT.
ANY LINGERING STORMS THURSDAY MORNING WILL SHIFT EAST AND
NORTHEAST OF THE CWA THROUGH MID DAY WITH A POSSIBILITY FOR
CONTINUED HEAVY RAINFALL. THESE DEPARTING STORMS COULD ALLOW FOR
CLEARING SKIES AND THE ENVIRONMENT TO DESTABILIZE ONCE AGAIN
DURING MID DAY AND EARLY AFTERNOON...WITH THE POSSIBILITY FOR
THUNDERSTORMS TO REDEVELOP ALONG LIFTING FRONTAL BOUNDARY.
CLEARING WILL BE KEY WITH POTENTIAL FOR INTENSITY OF THESE STORMS
ON THURSDAY BUT WITH STRONG TO SEVERE STORMS POSSIBLE...ESPECIALLY
IF A GOOD AMOUNT OF HEATING COULD OCCUR. FOCUS FOR THUNDERSTORMS
WILL CONTINUE THURSDAY NIGHT AS WELL...WITH HIGH MOISTURE CONTENT
AIR STILL IN PLACE. THIS WILL ALSO CONTINUE CONCERNS FOR HEAVY
RAINFALL ACROSS THE AREA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PERIODIC CHANCES FOR THUNDERSTORMS THROUGH THE PERIOD.
* SWLY WINDS GUSTING UP TO 20KT IN THE AFTERNOON.
KREIN
//DISCUSSION...UPDATED 06Z..
PRIMARY FORECAST CONCERN WILL REMAIN THE CHANCES FOR THUNDERSTORMS
OVER THE AREA. AT ISSUANCE TIME...A LINE OF SHOWERS AND A FEW
THUNDERSTORMS WAS DEVELOPING ALONG A NARROW CORRIDOR FROM AROUND
RFD TO JUST SOUTH OF MDW AND INTO NWRN INDIANA. THE PCPN IS
DEVELOPING ALONG AN ELEVATED WARM FRONT...WITH THE SFC WARM FRONT
STILL TO THE SOUTH...EXTENDING FROM LOW PRESSUURE OVER SOUTH
DAKOTA SOUTHEAST TO SRN IL. INDIVIDUAL CELLS ARE TRACKING TO THE
SOUTHEAST...WITH NWLY FLOW ALOFT...BUT THE AREA OF PCPN IS SLOWLY
LIFTING TO THE NORTH. GIVEN THE SOMEWHAT SCATTERED NATURE OF THE
PCPN AREA...HAVE ADDED VCSH MENTION BACK TO THE TAFS THROUGH 12Z.
HAVE RESISTED THE TEMPTATION TO CALL IS VCTS AS THERE IS LITTLE
LIGHTNING ACTIVITY. HOWEVER...TS SHOULD BECOME MORE OF AN ISSUE
FOR THE TERMINALS THROUGH THE DAY TOMORROW AS THE WARM FRONT
SLOWLY LIFTS TO THE NORTH. THE WARM FRONT SHOULD LIFT THROUGH NRN
IL/IN THROUGH THE DAY TOMORROW...PUTTING THE REGION IN THE WARM
SECTOR OF THE SYSTEM...WITH PERSISTENT WARM/MOIST ADVECTION. THE
ENVIRONMENT SHOULD BECOME INCREASINGLY UNSTABLE THROUGH THE DAY
AND ADDITIONAL THUNDERSTORM ACTIVITY IS LIKELY OVER THE AREA...BUT
CONFIDENCE REMAINS LOW IN THE EXACT TIMING AND COVERAGE OF THE
IMPACTS AT THE TERMINALS. SO...HAVE ONLY GONE WITH A VCTS FOR THE
MORNING HOURS...THOUGH CONFIDENCE IS HIGHER THAT THERE SHOULD BE
SOME TS AROUND THE AREA. HAVE KEPT THE TAFS DRY FOR THE AFTERNOON
HOURS...WITH THE SFC WARM FRONT PUSHING INTO WISCONSIN AND AN
ABSENSE OF UPPER LEVEL FORCING...THOUGH THERE STILL COULD BE SOME
ISOLD-SCT SHRA/TSRA. THERE SHOULD BE A BETTER CHANCE FOR MORE
ORGANIZED CONVECTION THUSDAY NIGHT AS THE MODELS ARE INDICATING A
RATHER VIGOROUS SHORTWAVE OVERTOPPING THE UPPER RIDGE OVER THE
MISSISSIPPI VALLEY AND TURNING SOUTHEAST ACROSS NRN IL. THIS
SHORTWAVE...COINCIDENT WITH THE WARM FRONT WHICH SHOULD BE CLOSE
TO THE WISCONSIN BORDER SHOULD PROVIDE BOTH SFC AND UPPER LEVEL
FORCING IN AN ALREADY MOIST AND UNSTABLE ENVIRONMENT. SO...HAVE
INTRODUCED TEMPO TS FOR THE EVENING HOURS AND A PROB30 FOR THE
LATE NIGHT HOURS. AS THE FORECAST PICTURE BECOME A BIT MORE
CLEAR...PREVAILING TS TIMING WILL LIKELY BE ADDED IN THE UPDATES
LATER TODAY.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM TO HIGH CONFIDENCE THAT THERE BE PERIODS OF SHOWERS AND
THUNDERSTORMS THROUGH THE FORECAST PERIOD...BUT LOW IN THE
TIMING AND COVERAGE.
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...PERIODIC CHANCES FOR TSRA.
KJB
&&
.MARINE...
158 PM CDT
FAIRLY LIGHT WIND REGIME IS EXPECTED THROUGH THE WEEKEND WITH WEAK
PRESSURE GRADIENT EXPECTED WITH HIGH PRESSURE OVER THE ST LAWRENCE
VALLEYS REGION AND A TROUGH OF LOW PRESSURE OVER THE NORTHERN AND
CENTRAL PLAINS. A QUASI-STATIONARY WARM FRONT WILL EXTEND EAST FROM
THE LOW INTO THE LOWER GREAT LAKES REGION...WITH THE POSITION OF THE
WARM FRONT LIKELY BEING MODULATED AT TIMES BY CONVECTIVE COMPLEXES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS DES MOINES IA
1154 PM CDT WED AUG 20 2014
.SHORT TERM /TONIGHT/...
ISSUED AT 340 PM CDT WED AUG 20 2014
TONIGHTS FORECAST IS QUITE DIFFICULT AND THE MODELS ARE NOT MUCH
HELP. A WARM FRONT ACROSS IOWA STRETCHES FROM A LOW OVER WEST
CENTRAL SOUTH DAKOTA. THETA-E ADVECTION AND SOME MODEST INSTABILITY
KEPT THUNDERSTORMS FESTERING AHEAD OF THE FRONTAL BOUNDARY ALL DAY
LONG AND SHEAR ACTUALLY INCREASED THROUGH THE AFTERNOON HOURS. THE
MODELS CONTINUE THE SHOWERS/STORMS ALONG AND AHEAD OF THE FRONTAL
BOUNDARY IN A ZONE OF WARM ADVECTION THROUGH THE AFTERNOON HOURS
INTO EARLY EVENING. THE HRRR AND HOPWRF THEN SQUELCH THE PRECIP IN
IOWA OVERNIGHT WHILE THE NAM CONTINUES TO DEVELOP STORMS ACROSS
NORTH CENTRAL/NORTHEAST IOWA...ESPECIALLY WITH A LOW LEVEL JET THAT
INTENSIFIES LATER THIS EVENING. IT IS VERY HARD TO SAY WHERE THAT
BOUNDARY WILL LIFT TO THIS EVENING...OR WILL IT REMAIN FAIRLY
STATIONARY. I AM REASONABLY CERTAIN THAT WE WILL NOT BE DRY ACROSS
THE NORTH BUT I AM SKEPTICAL ABOUT KEEPING 60-70 POPS IN THAT AREA
GIVEN THE TRENDS FOR THE PRECIP TO SLOWLY LIFT NORTH.
THE MAIN ADJUSTMENTS TO THE GOING FORECAST WERE TO LOWER POPS SOME
ACROSS THE NORTH AND MENTION HEAVY RAIN ACROSS A PART OF THE NORTH
CENTRAL AND NORTHEAST. HOWEVER...IF THE NAM12 IS CORRECT MY
FORECAST WILL NEED TO BE ADJUSTED ONCE THE LLJ COMES INTO PLAY AFTER
03Z OR SO AS HIGHER POPS WILL BE NEEDED FURTHER SOUTH. HEAVY
RAINFALL WILL ALSO BE MORE OF A CONCERN ACROSS AREAS NORTH OF
HIGHWAY 20.
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 340 PM CDT WED AUG 20 2014
RELATIVELY ACTIVE CONDITIONS TO PERSIST FOR MUCH OF THE LONG TERM
WITH BROAD WSW FLOW ALOFT AND SURFACE BOUNDARY NEARBY. ANY ONGOING
CONVECTION ON THURSDAY MORNING SHOULD DISSIPATE WITH FORCING
WEAKENING. WARM SECTOR WILL BE IN PLACE WITH TEMPERATURES CLIMBING
NICELY THROUGH THE DAY. STILL MAY SEE SOME MID TO HIGH CLOUDS
OVERHEAD AND THIS MAY LIMIT DAYTIME HIGHS...HOWEVER STILL A VERY
WARM AND HUMID DAY EXPECTED FOR MOST LOCATIONS. SURFACE BOUNDARY
WILL EASE INTO NORTHERN IOWA ON THURSDAY NIGHT WITH SOME SCATTERED
CONVECTION EXPECTED ALONG THE FRONT OVERNIGHT. THESE STORMS ARE
EXPECTED TO WEAKEN OVERNIGHT TOWARD DAYBREAK AS INFLOW WEAKENS AND
COL REGION PUSHES INTO THE STATE. FRIDAY WILL SEE THE COL PASS
THROUGH IOWA WITH LIMITED CONVECTION CHANCES FOR MUCH OF THE DAY.
HOWEVER...A MORE VIGOROUS SHORTWAVE WILL EJECT INTO THE PLAINS
LATER FRIDAY WITH INCREASING FLOW INTO THE FRONT LATE FRIDAY INTO
FRIDAY NIGHT. MODELS HAVE ALL BEEN INDICATING RATHER ROBUST
CONVECTION BY LATE FRIDAY ACROSS THE PLAINS PUSHING INTO IOWA
OVERNIGHT. HAVE CONTINUED THE HIGHER POPS ON FRIDAY
NIGHT...ESPECIALLY ACROSS THE NORTHWEST WHERE THE BEST FORCING AND
INFLOW INTO SYSTEM IS ANTICIPATED. THE THREAT FOR CONVECTION WILL
PERSIST INTO THE WEEKEND AND EARLY NEXT WEEK AS THE FRONTAL
BOUNDARY REMAINS NEAR THE STATE. AT THIS POINT...IT APPEARS MUCH
OF THE CONVECTION THIS WEEKEND WILL BE NEAR NORTHERN IOWA WITH HOT
AND HUMID CONDITIONS IN THE SOUTH. THE BULK OF THE SYSTEM IS NOT
EXPECTED TO PASS THROUGH THE REGION UNTIL THE MIDDLE OF NEXT WEEK
WHEN GOOD COVERAGE OF STORMS IS ANTICIPATED TUESDAY NIGHT INTO
WEDNESDAY. TEMPERATURES WILL REMAIN VERY WARM TO HOT SOUTH OF THE
BOUNDARY DURING THIS TIME.
THE THREAT FOR HEAVY RAINFALL WILL BE EVER PRESENT WITH THIS
CONVECTION FOR MUCH OF THE FORECAST. PWAT VALUES WILL IN GENERAL
BE AT OR ABOVE 1.50" WITH CONVECTION EAST OR SOUTHEAST AND
TRAINING A POSSIBILITY FROM TIME TO TIME. WHILE WIDESPREAD
FLOODING IS NOT EXPECTED GIVEN MATURE VEGETATIVE
GROWTH...LOCALIZED FLOODING MAY OCCUR. THE PRIMARY FLASH FLOOD
THREAT WILL REMAIN IN URBAN AREAS. HOWEVER...IF SEVERAL NIGHTS OF
RAIN DO OCCUR IN THE SAME AREA...A MORE GENERALIZED FLASH FLOOD
THREAT MAY MATERIALIZE.
THE OTHER CONCERN WILL BE WITH HOT AND HUMID CONDITIONS SOUTH OF
THE BOUNDARY. HEAT INDEX VALUES ARE EXPECTED TO CLIMB ABOVE 100
DEGREES FROM TIME TO TIME AND MAY BECOME PROBLEMATIC...ESPECIALLY
IN SOUTHERN IOWA SHOULD SEVERAL DAY STRING TOGETHER OF HOT AND
STICKY CONDITIONS. MUCH WILL DEPEND ON THE EXTEND OF CONVECTION
AND WHERE OUTFLOW BOUNDARYS AND SUBSEQUENT CONVECTION END UP. AT
THIS POINT...GIVEN THE UNCERTAINTY...NO HEADLINES FOR HEAT WILL BE
ISSUED.
&&
.AVIATION...21/06Z
ISSUED AT 1150 PM CDT WED AUG 20 2014
BOUNDARY NEAR NORTHERN IOWA WILL ALLOW FOR TSRA CHANCES AT SITES.
HAVE INCLUDED MENTION AT NORTHERN SITES KMCW/KALO...WITH
CONDITIONS DROPPING TO MVFR OR IFR...POSSIBLY LOWER IF HEAVY RAIN
REDUCES VISIBILITIES NEAR 12Z. SYSTEM WILL PUSH EAST...WITH A
RETURN TO VFR CONDITIONS AT SITES. WINDS WILL BE FROM THE SOUTH
AND MAY BE GUSTY IN THE AFTERNOON. ADDITIONAL CHANCES FOR
SHRA/TSRA WILL BE POSSIBLE AT SITES LATE IN THE PERIOD...THOUGH
HAVE LEFT OUT MENTION ATTM DUE TO UNCERTAINTIES IN TIMING AND
PLACEMENT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...COGIL
AVIATION...AWB
AREA FORECAST DISCUSSION
NWS TOPEKA KS
319 AM CDT Thu Aug 21 2014
.SHORT TERM...(Today and Tonight)
Issued at 245 AM CDT THU AUG 21 2014
Thunderstorms again not far from the local area and could skirt the
northwestern counties over the next few hours. This appears the
result of better moisture and moisture convergence via the low level
jet, with with southwest low-mid level flow likely keeping this
focused to the north. Some gustiness in surface winds has been
common overnight due to the stronger jet, helping keep temps in the
upper 70s to lower 80s.
Will keep small mention of precipitation very early in the far north
as decreasing mass flow occurs from the nocturnal jet mixing out
through the mid morning. Models are very similar with 850mb temps
rising another 1-2C with mixing well through this layer bringing
highs up in kind. Dewpoints should remain in the mid 60s to around
70 and bring apparent temps into the 101 to 105 range, but
confidence in the higher levels being widespread or more than brief
is too low for a Heat Advisory. For tonight, the low level jet,
though weaker, looks to be displaced a bit farther southeast, with
deep layer moisture increasing from the southwest. Setup doesn`t
appear as strong as that seen to the northwest this morning, but
small thunder chances seem in order for mainly northern and central
areas.
.LONG TERM...(Friday through Wednesday)
Issued at 245 AM CDT THU AUG 21 2014
Friday and through the weekend the heat continues, as upper ridge
remains solid to the east of the forecast area and noses northward
into the Great Lakes through this period. Shortwave lifts
northeast out of the desert southwest through the western
periphery of the upper high and into the northern plains by early
Sunday, bringing periodic chances for rain along our northern and
western borders. Eastern areas remain capped as influence of upper
ridge prevails. High temperatures may cool along the north if
clouds or rain chances can materialize, but mid to upper 90s
continue in the eastern counties. Heat indicies Friday near
100-105 and come down just a few degrees each day over the
weekend.
GFS and EC both lift leading shortwave trof into the northern
plains by late weekend. While both then lift the larger eastern
lobe of the upper trof into southern Canada, the EC is then deeper
and stronger with the next piece of energy to move into the back
side of the longwave trof over the Pacific Northwest. The GFS is
weaker and more progressive, and swings the trof across the plains
by the end of the forecast period Wednesday. The EC retrogrades
the energy, which boosts the upper high back northward into the
Central Plains. Mondays forecast would be influenced by how far
south the surface front can be pushed before southwesterly flow
aloft aids in pushing the front back northward. Unfortunately both
solutions would suggest even if Monday brings a cooler shot and a
chance for precipitation, that this push on Tuesday would make
short work of bringing the warm temperatures back north for
Tuesday. Progressive GFS would bring front through on Wednesday
while the EC holds in the heat another day. Later periods in the
forecast certainly reflect probabilistic chances for precipitation
and generally focus chances on the west and north where
perturbations in the flow have greater chances for influence.
&&
.AVIATION...(For the 06Z TAFs through 06Z Thursday Night)
Issued at 1120 PM CDT WED AUG 20 2014
Organized convection appears to be a pretty low probability
overnight with models showing the nose of the low level jet mainly
north and east of the terminals. Convection has persisted across
southern NEB on the nose of the low level jet while additional
activity to the south appears to be falling apart. Therefore will
continue with a dry forecast. Chances for wind shear continue to
be small as sfc winds have remained up this evening indicative of
continued mixing. RAP and NAM soundings show only a modest nocturnal
inversion that is not very steep and models prog a decent pressure
gradient persisting through the night. Because of this I do not
expect the boundary layer to become completely decoupled.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...65
LONG TERM...67
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1120 PM CDT Wed Aug 20 2014
...AVIATION UPDATE...
.SHORT TERM...(This Evening through Thursday)
Issued at 333 PM CDT WED AUG 20 2014
A broad upper level ridge axis will continue to amplify across the
lower and mid MS river valley over the next 24 hours.
A minor upper level trough was located across northeast OK and
southeast KS this afternoon, on the western edge of the H5 ridge
axis, and will move northeast across southeast KS into western MO
this afternoon through early this evening. A shower did pop up
across southern Coffey county but did dissipate. This minor H5
trough may provide just enough lift for an isolated shower or
thunderstorms along and southeast of I-35 through the late afternoon
and early evening hours. I will keep POPS at 14 percent due to the
very isolated coverage.
During the evening hours scattered thunderstorms will develop across
western KS and eastern CO. Most of the thunderstorms will lift
northeast into NE but the trailing edge of any thunderstorm complex
may move across portions of north central and northeast KS late
Tonight and through the mid morning hours of Thursday. At this time
any thunderstorm complex that develops across western KS Tonight
should be decaying through the early morning hours of Thursday, thus
the thunderstorms will not be severe as they move northeast into a
less favorable environment across northeast KS.
Thursday will be mostly sunny as the H5 ridge axis amplifies across
the southern and mid MS river valley. Thunderstorms should remain
well west and north of the CWA during the daylight hours. Highs will
warm into the mid to upper 90s once again. A few locations across
the southwestern counties of the CWA may reach the 100 degree mark.
Heat indices will warm into the 100 to 104 degree range during the
afternoon hours. Some isolated areas across east central KS may see
heat indices reach around 105 degrees.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 333 PM CDT WED AUG 20 2014
The mid-level flow will remain fairly unchanged through the end of
the week into the weekend with a broad ridge remaining in place
across much of the central and eastern U.S. and a trough positioned
over the western U.S. Thursday night through Saturday the models are
in good agreement with the mid-level trough currently over the
Pacific Northwest digging southward along the western Rockies with
the ridge amplifying further northward toward the Great Lakes
region. This pattern will keep southwesterly flow aloft across the
region, which will continue to support warm air advection through
the end of the week and into the weekend with 850MB temperatures
reaching into the 23C-26C degree range. Hot and humid conditions are
expected during that period as temperatures become unseasonably warm
with highs reaching into the middle to upper 90s Friday and
Saturday. These high temperatures combined with dewpoints reaching
into the mid 60s to low 70s will result in afternoon heat indices
soaring into the 100F to 104F degree range Friday and near 100F
degrees on Saturday. We will continue to monitor these conditions
closely to see if a heat advisory is needed for Friday. During this
period, surface low pressure will become anchored across much of
the Northern and Central Plains with a fairly stationary front
situated near north central Kansas. There doesn`t appear to be much
in the way of forcing along this boundary, however there may be
scattered chances for precipitation from late week through the early
weekend, especially across north central and northern Kansas. At
this time, the better chances for precipitation look to be during
the evening and overnight hours as the low-level jet increases over
the region.
Saturday night and Sunday, models show a strong embedded shortwave
trough lifting northeastward across the northern Rockies and into
the Northern Plains. This advancing shortwave should be enough to
slowly push the stationary front eastward through the region Sunday
night and Monday, so have more widespread chance PoPs during that
period. This cold front may lift back northward across the area as a
warm front, however there is model uncertainty with regards to how
far north this warm front will lift, so confidence is low with
precipitation chances Monday night through Wednesday. At this time
have slight to low-end chance PoPs through that period.
The frontal passage Sunday night into Monday will cause winds to
shift to the north, providing a bit of relief to the heat with highs
dropping into the middle 80s to low 90s Monday. Temperatures are
more uncertain for Tuesday and Wednesday depending upon where the
warm front is located and whether or not the region is situated
within the warm sector, so have highs remaining in the upper 80s to
low 90s at this time.
&&
.AVIATION...(For the 06Z TAFs through 06Z Thursday Night)
Issued at 1120 PM CDT WED AUG 20 2014
Organized convection appears to be a pretty low probability
overnight with models showing the nose of the low level jet mainly
north and east of the terminals. Convection has persisted across
southern NEB on the nose of the low level jet while additional
activity to the south appears to be falling apart. Therefore will
continue with a dry forecast. Chances for wind shear continue to
be small as sfc winds have remained up this evening indicative of
continued mixing. RAP and NAM soundings show only a modest nocturnal
inversion that is not very steep and models prog a decent pressure
gradient persisting through the night. Because of this I do not
expect the boundary layer to become completely decoupled.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...Hennecke
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
435 AM CDT THU AUG 21 2014
.DISCUSSION...
11-3.9U SATELLITE IMAGERY THIS MORNING INDICATES A VORTICITY MAXIMUM
OVER NCNTRL LA...WHICH IS ALONG A ELEVATED WEAK SHEAR AXIS NOTED ON
THE WATER VAPOR LOOP EXTENDING FROM SE TX ACROSS NCNTRL LA INTO CNTRL
MS/NRN AL. THIS FEATURE HAS MAINTAINED AN EXTENSIVE AC CANOPY THIS
MORNING OVER MUCH OF NCNTRL LA...WHICH ARE THE CONVECTIVE REMNANTS OF
THE ISOLATED SEABREEZE CONVECTION THAT AFFECTED THESE AREAS WEDNESDAY
AFTERNOON AND EVENING. A WEAK UPPER LOW NOTED ON THE WATER VAPOR LOOP
NOW AFFECTING THE ERN MX COAST S OF BRO HAS ALREADY RESULTED IN
ENHANCED ONSHORE FLOW WHICH HAS LED TO INCREASED MOISTURE CONVERGENCE
ALONG A W TO E SFC TROUGH WHICH LIES NEAR THE I-10 CORRIDOR. THIS HAS
RESULTED IN ISOLATED CONVECTION DEVELOPING/STREAMING N ACROSS SW
LA...BUT HAVE WEAKENED WHERE SFC CONVERGENCE IS LOST FARTHER N OF THE
SFC TROUGH. THE PROGS DO WEAKEN THE VORT MAX LATER TODAY AS THE CENTER
OF THE 500MB RIDGE BEGINS TO BUILD NNW INTO THE LOWER MS VALLEY...BUT
SHOULD STILL SEE ANOTHER DAY WHERE SEABREEZE CONVECTION WILL AFFECT
THE SRN ZONES MAINLY DURING THE AFTERNOON/EARLY EVENING. GIVEN THE SSW
850-700MB FLOW...THE SEABREEZE SHOULD NOT PUSH AS FAR N ACROSS E TX/NW
LA AS IT HAS IN RECENT DAYS...BUT THE HRRR AND GFS SUGGEST THAT THE
CONVECTION COULD PUSH FARTHER NNE ACROSS THE ERN SECTIONS OF NCNTRL
LA. FOR THAT REASON...HAVE EXTENDED SLIGHT CHANCE POPS FARTHER N INTO
LINCOLN/UNION/OUACHITA PARISHES THIS AFTERNOON/EVENING...BUT A
STABILIZING BNDRY LYR FROM THE LOSS OF HEATING RESULTS IN THE QUICK
DISSIPATION OF THE CONVECTION. DID ALSO INCLUDE LOW CHANCE POPS FOR
THE SE SECTIONS OF NCNTRL LA...WHERE EXTRAPOLATION OF THE CURRENT
CONVECTION WILL LIKELY RESULT IN ADDITIONAL OUTFLOW BNDRYS THAT WILL
FOCUS MORE SCT DEVELOPMENT ESPECIALLY WHEN PEAK HEATING IS REACHED.
WITH THE AC SHIELD GRADUALLY THINNING BY AFTERNOON...AND THE MORNING
LOW STRATUS QUICKLY LIFTING THIS MORNING...MAX TEMPS TODAY SHOULD BE
NEAR IF NOT SLIGHTLY WARMER THAN WHAT WAS OBSERVED WEDNESDAY.
THE HEAT IS ON FRIDAY THROUGH EARLY NEXT WEEK AS THE CENTER OF THE
UPPER RIDGE RESIDES IN VC OF OUR REGION OVER LOWER MS VALLEY. THIS
SHOULD RESULT IN MAX TEMPS CLIMBING INTO THE UPPER 90S AREAWIDE BY THE
WEEKEND...WITH A FEW TRIPLE DIGIT TEMPS NOT OUT OF THE QUESTION OVER
PORTIONS OF THE REGION. EVEN WITH THE 700MB RIDGE CENTERED OVER ERN AR
SUNDAY...AMPLE SOIL MOISTURE OVER ERN LA/SE AR SHOULD HELP MAINTAIN
TEMPS BELOW THE CENTURY MARK...BUT RESULT IN HIGHER DEWPOINTS/HEAT
INDICES SUCH THAT A HEAT ADVISORY MAY BE NEEDED FOR PORTIONS OF NCNTRL
LA/S AR THIS WEEKEND. HAVE TRENDED SLIGHTLY COOLER THAN MAVMOS THIS
WEEKEND...ESPECIALLY GIVEN ITS WARM BIAS FOR THE LAST SEVERAL WEEKS.
THE PROGS CONTINUE TO SHIFT THE UPPER RIDGE CENTER FARTHER NE INTO THE
MID MS VALLEY BY MONDAY WITH THE RIDGE AMPLIFYING INTO THE GREAT LAKES
REGION...WITH THE EXTREME HEAT BEGINNING TO WEAKEN ITS GRIP ON OUR
AREA. BUT THIS WILL BE GRADUAL...UNTIL WEAKNESSES BENEATH THE RIDGE
CENTER ARE ABLE TO MIGRATE W ACROSS MS/SE LA MONDAY...WHICH MAY TOUCH
OFF ISOLATED CONVECTION OVER MUCH OF NCNTRL LA/DEEP E TX. WITH THESE
WEAKNESSES NUDGING CLOSER TO OUR REGION BY TUESDAY...MORE IN THE WAY
OF SCT CONVECTION IS EXPECTED OVER NCNTRL LA/DEEP E TX...WITH ISOLATED
CONVECTION POSSIBLE FARTHER W. FORECAST CONFIDENCE DIMINISHES
THEREAFTER...WITH THE GFS SUGGESTING AN UPPER TROUGH QUICKLY SHIFTING
E ACROSS THE PLAINS WEDNESDAY AND ACROSS THE SRN PLAINS/LOWER MS
VALLEY THURSDAY. MEANWHILE...THE ECMWF REMAINS STOUT WITH THE RIDGE
CENTER ACTUALLY RETROGRADING W BACK ACROSS THE CNTRL CONUS...WITH A
MUCH SLOWER AND WEAKER TROUGH PASSAGE /IF ANY AT ALL/ BY NEXT WEEKEND.
FOR NOW...HAVE MAINTAINED SLIGHT CHANCE POPS THROUGHOUT THE REMAINDER
OF THE EXTENDED...WHILE KEEPING NEAR NORMAL TEMPS THROUGH THE PERIOD.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 96 74 97 74 98 / 5 5 0 0 0
MLU 94 73 96 73 97 / 20 20 0 0 0
DEQ 94 72 95 72 96 / 0 0 0 0 0
TXK 95 74 96 74 97 / 0 0 0 0 0
ELD 94 72 96 73 97 / 5 5 0 0 0
TYR 97 75 97 75 97 / 5 5 0 0 0
GGG 95 74 96 74 97 / 5 5 0 0 0
LFK 96 74 97 74 97 / 20 10 0 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
15
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 AM CDT THU AUG 21 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT THU AUG 21 2014
MODELS IN FAIR AGREEMENT IN NEAR TERM AND WILL USE A BLEND FOR
THE FORECAST. UPPER HIGH PARKED OVER LOUISIANA THIS MORNING WITH
CLOSED LOW OVER PACIFIC NORTHWEST AND TROUGH THROUGH THE DESERT
SOUTHWEST. WESTERN NEBRASKA CONTINUES IN THE RING OF FIRE BETWEEN
FEATURES. ONGOING PRECIPITATION THIS MORNING LOOKS TO LINGER
THROUGH THE MORNING WITH CLUSTER OF STORMS OVER NORTHEAST
COLORADO BRINGING CHANCES OF PRECIPITATION TO SOUTHWEST AND THE
SOUTHEAST NEBRASKA PANHANDLE. HAVE RETAINED SLIGHT CHANCES FOR
ISOLATED SHOWERS AND THUNDERSTORMS. AS THE DISTURBANCE ON
SATELLITE MOVES ACROSS WESTERN NEBRASKA EARLY THIS MORNING
SHOWERS TO END. PARTLY CLOUDY SKIES TODAY WITH SURFACE LOW OVER
NORTH CENTRAL KANSAS. WOULD EXPECT BEST CHANCES FOR THUNDERSTORM
DEVELOPMENT OVER THE NEBRASKA PANHANDLE AND NORTHEAST COLORADO
LATE THIS AFTERNOON WITH HEATING OF THE DAY AND WEAK WAVE MOVING
THROUGH SOUTHWEST FLOW OUT OF THE BOTTOM OF THE TROUGH TO THE
WEST. HIGHS TODAY AROUND 90 OVER WESTERN NEBRASKA. TONIGHT SLIGHT
CHANCES RETAINED FOR THUNDERSTORMS OVER THE WEST AND SOUTHWEST.
NO MAJOR WAVES MOVING THROUGH SOUTHWEST FLOW BUT A COLD FRONT
WILL MOVE INTO WESTERN SOUTH DAKOTA AND INTO SOUTHWEST SOUTH
DAKOTA TONIGHT. SOUTHWEST FLOW WILL KEEP TEMPERATURES IN THE MID
60S OVER NIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 356 AM CDT THU AUG 21 2014
MODELS IN GOOD AGREEMENT FOR THE WEEKEND AS COOLER CONDITIONS
ARRIVE...HOWEVER DIFFERENCE DEVELOP BY MIDWEEK WITH RETURN OF
WARMER TEMPS.
FRIDAY INTO SATURDAY WILL SEE A TROUGH DEEPEN ACROSS THE PACIFIC
NORTHWEST AS A RIDGE AMPLIFIES ACROSS THE MISS RVR VALLEY. THE
SOUTHWEST FLOW WILL TAP THE PACIFIC MONSOON FLOW WITH POPS LIKELY
EARLY IN THE WEEKEND. PARTLY TO MOSTLY CLOUDY SKIES AND PERIODIC
CHANCES FOR RAIN WILL HOLD TEMPS IN THE 70S TO LOWER
80S...HOWEVER EXPECT A FEW BREAKS IN THE CLOUDS AND WILL ALLOW
TEMPS TO SURGE INTO THE 80S FOR MOST AREAS. SOME CONCERNS ON
TEMPS AS CLOUDS COULD HOLD STRONG WITH NO BREAKS AND KEEP TEMPS
LOWER.
SUNDAY INTO THE FIRST OF THE WEEK THE TROUGH WILL CROSS THE
ROCKIES AND PUSH ONTO THE NORTHERN PLAINS. A COLD FRONT WILL PUSH
ACROSS THE CWA SUNDAY WITH COOLER CONDITIONS EXPECTED...GENERALLY
70S TO AROUND 80 IN THE SW. WILL ALSO SEE LOW CHANCES FOR
RAINFALL AS A COUPLE OF DISTURBANCES ROTATE AROUND THE NORTHERN
LOW.
MODELS THEN DIVERGE AS THE ECMWF HAS SHIFTED FROM RECENT
TRENDS...BRINGING WARMER AIR QUICKLY BACK TO THE REGION. THE GFS
REMAINS CONSISTENT WITH THE COOLER CONDITIONS ACROSS THE HIGH
PLAINS. WILL FOLLOW CLOSER TO THE PERSISTENT FORECAST AND THE
GFS...AND WAIT TO SEE IF THE WARMER EC SOLUTION GETS ADDITIONAL
SUPPORT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1128 PM CDT WED AUG 20 2014
INDICATIONS FROM THE HRRR AND NAM MODELS SUGGEST THE ONGOING
CONVECTION COULD LAST SEVERAL MORE HOURS AS IT SHIFTS SLOWLY EAST
OVERNIGHT EXITING BY 12Z. VFR IS EXPECTED ALL AREAS THEREAFTER.
STRONG WINDS ALOFT AND VERY UNSTABLE AIR LATE THURSDAY AFTERNOON
AND EVENING WOULD LIKELY CAUSE TSTM DEVELOPMENT ONCE AGAIN EXCEPT
THE MODELS SUGGEST LITTLE IN THE WAY OF AN UPPER LEVEL
DISTURBANCE. SO POPS ARE ISOLATED LATE THURSDAY IN THE WEST AND
ALONG OR EAST OF HIGHWAY 83.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...POWER
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1148 PM CDT WED AUG 20 2014
.SHORT TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 334 PM CDT WED AUG 20 2014
UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE OVER THE NEXT WEEK
WITH SEVERAL OPPORTUNITIES FOR THUNDERSTORMS. TIMING THESE CHANCES
ALONG WITH INCREASE IN HEAT AND HUMIDITY ARE THE PRIMARY FORECAST
CONCERNS.
MORNING UPPER AIR CHARTS SHOWED MID LEVEL TROUGH EXTENDING FROM THE
CANADIAN ROCKIES INTO SOUTHERN CALIFORNIA...WITH SOUTHWEST FLOW
AHEAD OF THE TROUGH RIDING INTO THE NORTHERN PLAINS. UPPER RIDGE
AXIS WAS CURRENTLY OVER THE MISSOURI RIVER VALLEY...BUT IS FORECAST
TO SHIFT EAST AND FLATTEN A BIT ON THURSDAY. THIS WILL LEAVE OUR
AREA UNDER SOUTHWEST FLOW ALOFT...WITH PATH FOR EJECTING SHORTWAVES
OVER NEBRASKA AND THE DAKOTAS. ALSO OF NOTE WAS PLUME OF MID LEVEL
MOISTURE EXTENDING FROM THE SOUTHERN BAJA INTO WESTERN KANSAS AND
SOUTHWEST NEBRASKA. WITH ONLY A SLOW DRIFT TO WESTERN
TROUGH...EXPECT THIS MOISTURE PLUME TO EXPAND OVER EASTERN NEBRASKA
AND WESTERN IOWA AND REMAIN IN PLACE AT LEAST INTO THE WEEKEND.
USING 700MB DEW POINT TEMPERATURES AS A PROXY...MODELS CONCUR WITH
THIS EXPECTATION. THE RESULT OF THESE PARAMETERS WILL BE AN
ATMOSPHERE PRIMED FOR SCATTERED CONVECTION AS SHORTWAVES ROLL INTO
THE PLAINS.
TIMING OF THOSE SHORTWAVES WILL PROVE DIFFICULT MORE THAN A DAY TO
TWO OUT. HOWEVER MODELS AGREE ON A SIGNIFICANT SHORTWAVE MOVING INTO
THE PLAINS FRIDAY NIGHT...OUR MOST LIKELY TIME FOR WIDESPREAD HEAVY
RAINS.
FOR TONIGHT...WATER VAPOR LOOPS IMPLY A SHORTWAVE IN WESTERN KANSAS
THIS AFTERNOON...EXPECTED TO LIFT NORTHEAST ACROSS OUR CWA LATER
THIS EVENING AND OVERNIGHT. GREATER THAN 7 C/KM MID LEVEL LAPSE
RATES WILL BE IN PLACE ALONG WITH ABUNDANT MID LEVEL MOISTURE.
EXPECT SCATTERED THUNDERSTORMS TO FIRE AFTER MIDNIGHT WHEN LOW LEVEL
JET KICKS UP TO 35KT WITH APPROACH OF SHORTWAVE. MAIN AREA OF
CONCERN WILL BE OVER OUR NORTHERN CWA THEN. HOWEVER THIS
EVENING...CONVECTION FROM EARLIER THIS MORNING MOVING ACROSS IOWA
LAID DOWN AN OUTFLOW BOUNDARY WHICH MOVED INTO SOUTHWEST IOWA AND
NORTHERN MISSOURI. VISIBLE SATELLITE PICS SHOW A LINE OF CUMULUS
ALONG THIS BOUNDARY...AND RAP MODEL SUGGESTS MLCAPE IS APPROACHING
3500 J/KG IN NORTHWEST MISSOURI ALONG WITH DIMINISHING CAP. LATEST
RAP AND HRRR FORECASTS KEEP CONVECTION IN CHECK THERE...BUT HAVE
ADDED SMALL POPS FOR SEVERAL HOURS THIS EVENING.
OVERNIGHT CONVECTION SHOULD BE EXITING THE CWA OR DIMINISHING BY MID
MORNING. EXPECT CLOUDS TO CLEAR ALLOWING FOR PLENTY OF INSOLATION IN
THE AFTERNOON WITH TEMPERATURES WELL INTO THE 90S AND DEW POINTS
CLOSE TO 70. A WEAK FRONTAL BOUNDARY IS FORECAST TO SETTLE INTO
NORTHEAST NEBRASKA THURSDAY AFTERNOON BEHIND WEDNESDAY NIGHT
SHORTWAVE...AND COULD FOCUS THUNDERSTORM CHANCES THERE. RELATIVELY
WARM TEMPERATURES ALOFT WILL LIKELY SUPPRESS CONVECTION IN THE
AFTERNOON...WITH BETTER CHANCES COMING LATER IN THE EVENING AS THE
FRONT SETTLES SOUTH INTO SOUTHEAST NEBRASKA AND SOUTHWEST IOWA AND
MID LEVEL TEMPERATURES COOL A BIT. CONTINUED ISENTROPIC UPGLIDE OVER
FRONTAL BOUNDARY IN MOIST ATMOSPHERE SUGGESTS AT LEAST SCATTERED
CONVECTION IS POSSIBLE THROUGH THE NIGHT.
MOST OF DAY FRIDAY SHOULD BE DRY AFTER MORNING STORMS IN THE SOUTH
MOVE OFF TO THE EAST. FRONTAL BOUNDARY WILL BEGIN LIFTING TO THE
NORTH DURING THE DAY WITH APPROACH OF STRONG SHORTWAVE FRIDAY NIGHT.
INSTABILITY FORECASTS SHOW 2000-3000 J/KG OF SURFACE-BASED CAPE
FRIDAY AFTERNOON...BUT SOUNDINGS SUGGEST A MODEST CAP WILL HOLD OFF
STORMS UNTIL NEAR 00Z OR PROBABLY AFTER. CHANCES INCREASE MARKEDLY
FRIDAY NIGHT AS SHORTWAVE AND SURFACE LOW MOVE NORTHEAST THROUGH THE
CWA. CURRENT TRACK PLACES NORTHEAST NEBRASKA IN THE CORRIDOR OF
HEAVIEST POTENTIAL RAINFALL WHERE PRECIPITABLE WATER WILL LIKELY
EXCEED 2 INCHES. CURRENT HPC QPF PROGS PAINT ABOUT THREE-QUARTERS OF
AN INCH OF RAIN IN NORTHEAST NEBRASKA...BUT WILL LIKELY SEE MUCH
MORE THAN THAT IN LOCAL AREAS GIVEN MOISTURE AVAILABLE AND POTENTIAL
FOR TRAINING OF STORMS. EXPECT ACTIVITY TO BE EXITING TO OUR
NORTHEAST SATURDAY MORNING...BUT LEFTOVER BAROCLINIC ZONE AND WIND
SHIFT WILL REMAIN IN PLACE FOR THE POTENTIAL FOR MORE STORMS LATER
IN THE DAY SATURDAY. WILL MAINTAIN A SMALL CHANCE FOR ADDITIONAL
AFTERNOON STORMS...EXPECTING SUBSIDENCE BEHIND EXITING SHORTWAVE TO
SUPPRESS CONVECTION MOST OF THE AFTERNOON.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 334 PM CDT WED AUG 20 2014
CONTINUED CHANCES OF THUNDERSTORMS WILL REMAIN JUST ABOUT EACH
PERIOD IN THE LONGER TERM FORECAST THROUGH WEDNESDAY. WESTERN UPPER
TROUGH WILL SLOWLY DRIFT FROM THE ROCKIES SATURDAY NIGHT INTO THE
PLAINS BY WEDNESDAY. ECMWF IS A LITTLE MORE PROGRESSIVE THAN THE GFS
WITH THIS MOVEMENT...BUT EVEN THE ECMWF LEAVES SOME SEMBLANCE OF A
TROUGH/LOW IN THE PLAINS THEN.
USING A BLEND OF ECMWF AND GFS...AND WHERE SOME CONSISTENCY IS
SHOWN...BEST CHANCES FOR MORE WIDESPREAD CONVECTION IS EXPECTED
MONDAY NIGHT INTO TUESDAY...THEN AGAIN TUESDAY NIGHT INTO WEDNESDAY.
BEFORE THEN...IMPULSES RIDING THROUGH MID LEVEL FLOW COULD SPARK
AREAS OF STORMS AT JUST ABOUT ANY TIME AS FRONTAL BOUNDARY MEANDERS
NORTH AND SOUTH THROUGH THE CWA AHEAD OF AND BEHIND EACH WAVE.
TEMPERATURES SHOULD MODERATE SOME THROUGH THE PERIOD...BEGINNING
WITH SUNDAY IN THE 80S TO NEAR 90...THEN RANGING FROM THE UPPER 70S
TO MIDDLE 80S MONDAY THROUGH WEDNESDAY.
&&
.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1148 PM CDT WED AUG 20 2014
VFR CONDITIONS ARE EXPECTED AT THE TAF SITES. A FEW SCATTERED
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA DURING
AROUND SUNRISE...HOWEVER CONFIDENCE IS FAIRLY LOW.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...KERN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1132 PM CDT WED AUG 20 2014
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 354 PM CDT WED AUG 20 2014
RATHER DIFFICULT FORECAST TONIGHT. THERE HAVE BEEN LOTS OF MID LEVEL
CLOUDS HANGING ACROSS THE AREA THIS AFTERNOON...AND HAVE KEPT
TEMPERATURES DOWN A BIT. CLOUDS HAVE BEGUN TO CLEAR SLOWLY...AND ARE
NOW ALLOWING FOR SOME HEATING AND INCREASING INSTABILITY. DO NOT
HAVE A GOOD FEEL IN TERMS OF CONVECTION TONIGHT...AS MODELS HAVE
BEEN INCONSISTENT AND PRIMARY FORCING REMAINS MOSTLY NORTH OF THE
AREA. FOR THESE REASONS...WILL LOWER POPS A BIT. AS
MENTIONED...INSTABILITY IS INCREASING WITH LITTLE SURFACE BASED CIN
REMAINING ACROSS THE AREA. AN ELONGATED AREA OF LOW PRESSURE EXTENDS
FROM WESTERN SD TO WESTERN KS...AND COULD BE THE FOCUS FOR ISOLATED
STORM DEVELOPMENT THOUGH THE EVENING. A WARM FRONT ALSO EXTENDS FROM
WEST TO EAST ACROSS NORTHERN NEBRASKA...AND COULD ALSO SERVE AS A
FOCUS FOR STORM DEVELOPMENT. YET ANOTHER AREA TO WATCH WILL BE
ACROSS NORTHEAST COLORADO THIS EVENING...AS HRRR MODEL CONTINUES TO
INDICATE STORMS MOVING NORTHEAST INTO SOUTHWEST NEBRASKA THIS
EVENING. SO LOTS OF AREAS TO WATCH...BUT LOW CONFIDENCE ON ANY ONE
SCENARIO MATERIALIZING. WILL CONTINUE TO MONITOR.
WEAK COOL FRONT WILL SETTLE JUST SOUTHEAST OF THE AREA THURSDAY.
OVERALL SHOULD BE A FAIRLY QUITE WEATHER DAY...WITH LIGHT NORTH
WINDS AND TEMPERATURES IN THE UPPER 80S AND LOWER 90S.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT WED AUG 20 2014
MAIN FOCUS WILL BE THE STORM SYSTEM MOVING IN THIS WEEKEND WITH
THUNDERSTORM CHANCES THURSDAY THROUGH SUNDAY.
LOWERED PRECIPITATION CHANCES ACROSS THE SOUTHERN PART OF THE
FORECAST AREA AS THE LATEST MODELS ARE TRENDING DRIER DUE TO LACK
OF MOISTURE. KEPT THE POPS ACROSS THE NORTHWEST AS MODELS SEEM TO
FAVOR STRONGER FORCING AND BETTER MOISTURE AS AN UPPER LEVEL SHORT
WAVE TROF PUSHES ACROSS THE AREA. HELD OFF HIGHER PRECIPITATION
CHANCES ACROSS THE SOUTHWEST UNTIL FRIDAY AFTERNOON AND EVENING AS
CONFIDENCE IS GREATER IN THUNDERSTORM DEVELOPMENT AFTER 18Z. SYSTEM
CURRENTLY ACROSS THE SOUTHWESTERN U.S. WILL CONTINUE TO ADVECT
NORTHEASTWARD AND WILL COMBINE WITH THE NORTHERN SYSTEM CURRENTLY
ACROSS THE GULF OF ALASKA. THE SOUTHWEST SYSTEM WILL TRANSPORT
MOISTURE AND VORTICITY ACROSS THE FORECAST AREA FRIDAY AFTERNOON.
BY 00Z SATURDAY PRECIPITABLE WATER INCREASES TO 150 PERCENT.
SATURDAY NIGHT INTO SUNDAY...AN UPPER LEVEL SHORT WAVE TROF WILL
PUSH ACROSS THE FORECAST AREA PUSHING THE RIDGE EASTWARD BRINGING
COLDER TEMPERATURES WITH IT. HIGHS ON SUNDAY WILL BE AROUND 10
DEGREES COOLER THAN SATURDAY. COOLER TEMPERATURES WILL CONTINUE
THROUGH WED WHEN NEXT TROF IS SET TO PUSH THROUGH THE AREA. THIS
SYSTEM WILL BRING STRONG LIFT AS MODELS SUGGEST AN INCREASE IN OMEGA
VALUES AND AN ABUNDANT AMOUNT OF MOISTURE WITH DEWPOINTS IN THE 60S
CREATING A FAVORABLE THUNDERSTORM DEVELOPMENT TO BE IN PLACE THE
NEXT SEVERAL DAYS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1128 PM CDT WED AUG 20 2014
INDICATIONS FROM THE HRRR AND NAM MODELS SUGGEST THE ONGOING
CONVECTION COULD LAST SEVERAL MORE HOURS AS IT SHIFTS SLOWLY EAST
OVERNIGHT EXITING BY 12Z. VFR IS EXPECTED ALL AREAS THEREAFTER.
STRONG WINDS ALOFT AND VERY UNSTABLE AIR LATE THURSDAY AFTERNOON
AND EVENING WOULD LIKELY CAUSE TSTM DEVELOPMENT ONCE AGAIN EXCEPT
THE MODELS SUGGEST LITTLE IN THE WAY OF AN UPPER LEVEL
DISTURBANCE. SO POPS ARE ISOLATED LATE THURSDAY IN THE WEST AND
ALONG OR EAST OF HIGHWAY 83.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...TAYLOR
LONG TERM...GOMEZ
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
246 AM EDT THU AUG 21 2014
.SYNOPSIS...
AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST
ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF
HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD
ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 7 AM THIS MORNING/...
WATER VAPOR LOOP AT 05Z SHOWING SHORTWAVE OVR WESTERN PA ROTATING
THRU BASE OF UPPER LOW. THIS FEATURE IS SUSTAINING LINGERING
CONVECTION ACROSS THE CENTRAL MTNS AT 05Z AND LATEST RAP/HRRR
OUTPUT SUGGEST DWINDLING SHRA AND A FEW TSRA WILL PUSH INTO THE
EASTERN COUNTIES BEFORE EXITING THE AREA ARND DAWN. BASED ON RADAR
TRENDS AND RAP/HRRR DATA...WILL MAINTAIN HIGHEST /CHC/ POPS ACROSS
THE MID SUSQ VALLEY AND MTNS N OF IPT DURING THE PRE-DAWN HOURS.
WET GROUND...LGT WIND AND CLEARING SKIES BEHIND SHORTWAVE SHOULD
PROMOTE AREAS OF FOG EARLY THIS MORNING. DWPTS INDICATE MIN TEMPS
WILL RANGE FROM THE L/M60S ACROSS THE REGION.
&&
.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM FRIDAY/...
THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE
EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS
FORECAST TO DRIVE INTO THE OHIO VALLEY.
LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE
MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO
THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO
1800JKG-1 RANGE SECOND HALF OF THE DAY.
BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE
AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS.
OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS
WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z
TIMEFRAME.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN
LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION
POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE
THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT
CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS
SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE
MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL
PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF
UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE
CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL
PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE
ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY
FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY
NEXT WEEK AS RIDGE BUILDS OVER THE REGION.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
UPPER LEVEL S/WV CURRENTLY ROTATING ACROSS CENTRAL PA IS HELPING
TO SUSTAIN ISOLD CONVECTION OVER THE AIRSPACE EARLY THIS MORNING.
ONLY TERMINAL IMPACT ATTM APPEARS TO BE IPT WHICH SHOULD GET A
-SHRA WITH A FEW LTG STRIKES NEARBY 07-08Z. HRRR/COSPA DATA SHOWS
LINGERING SHOWERS DISSIPATING OR MOVG E THROUGH DAYBREAK.
FOG AND LOW CLOUDS LKLY TO BE MORE OF A FACTOR EARLY THIS MORNING
GIVEN RECENT RAIN/WET GROUND...LIGHT WINDS AND HIGH BOUNDARY
LAYER MOISTURE/SFC DEWPOINTS IN THE 60S. CUT BACK ON EXTENT OF IFR
CONDS FROM PREVIOUS FCST WITH HIGHEST CONFIDENCE AT TERMINALS THAT
RECEIVED DECENT RAINFALL YESTERDAY. REDUCED CONDITIONS SHOULD
IMPROVE TO VFR BY MID-LATE MORNING. A CONSENSUS OF HIRES MDL
GUIDANCE INDICATES MORE DISORGANIZED/WDLY SCT SHRA AND TSTMS
DEVELOPING THIS AFTN. WILL LKLY ADD SOME MENTION INTO 12Z TAFS BUT
FOR NOW WENT WITH SCT-BKN 040-050. ANTICIPATE DECREASING CVRG OF
SHRA AND TSTMS INTO THE LATE EVE/OVERNIGHT PERIOD WITH AREAS OF
FOG/ST DEVELOPING AGAIN WITH SOME CLEARING/LGT WINDS/MOIST
AIRMASS.
OUTLOOK...
FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF
MVFR/IFR RESTRICTIONS.
SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
105 AM EDT THU AUG 21 2014
.SYNOPSIS...
AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST
ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF
HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD
ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 7 AM THIS MORNING/...
WATER VAPOR LOOP AT 05Z SHOWING SHORTWAVE OVR WESTERN PA ROTATING
THRU BASE OF UPPER LOW. THIS FEATURE IS SUSTAINING LINGERING
CONVECTION ACROSS THE CENTRAL MTNS AT 05Z AND LATEST RAP/HRRR
OUTPUT SUGGEST DWINDLING SHRA AND A FEW TSRA WILL PUSH INTO THE
EASTERN COUNTIES BEFORE EXITING THE AREA ARND DAWN. BASED ON RADAR
TRENDS AND RAP/HRRR DATA...WILL MAINTAIN HIGHEST /CHC/ POPS ACROSS
THE MID SUSQ VALLEY AND MTNS N OF IPT DURING THE PRE-DAWN HOURS.
WET GROUND...LGT WIND AND CLEARING SKIES BEHIND SHORTWAVE SHOULD
PROMOTE AREAS OF FOG EARLY THIS MORNING. DWPTS INDICATE MIN TEMPS
WILL RANGE FROM THE L/M60S ACROSS THE REGION.
&&
.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM FRIDAY/...
THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE
EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS
FORECAST TO DRIVE INTO THE OHIO VALLEY.
LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE
MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO
THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO
1800JKG-1 RANGE SECOND HALF OF THE DAY.
BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE
AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS.
OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS
WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z
TIMEFRAME.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN
LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION
POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE
THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT
CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS
SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE
MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL
PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF
UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE
CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL
PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE
ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY
FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY
NEXT WEEK AS RIDGE BUILDS OVER THE REGION.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
NOT A LOT OF CHANGE TO 03Z TAFS.
EARLIER DISCUSSION BELOW.
DID NOT CHANGE A LOT ON THE 00Z TAF PACKAGE FROM THE EARLIER
SET.
MAIN CONCERN IS CONVECTION ACROSS THE NW NEAR BFD. OTHER
WIDELY SCATTERED SHOWERS AND STORMS COULD MOVE EAST INTO
THE REST OF THE AREA OVERNIGHT.
MAIN ISSUE FOR AVN CONCERN OVERNIGHT WILL BE FOG AND LOW
CLOUDS WITH LGT/VRB WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS.
FOR THIS...WENT CLOSE TO EARLIER FCST. DID LOWER CIGS IN
SOME CASES. A BLEND OF GUIDANCE AND TIMING FROM LAST NIGHT.
FOR THU...EXPECT LESS SHOWER AND THUNDERSTORM ACTIVITY...AS
THE WIND SHIFT LINE AND DYNAMICS SHIFT EASTWARD.
OUTLOOK...
FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS
OF SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS.
SUN-MON...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...MARTIN/STEINBUGL
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
347 AM CDT THU AUG 21 2014
.DISCUSSION...
SOME OBSERVATIONS ARE NOW INDICATING LOW CLOUDS STARTING TO FORM
TONIGHT. THESE WILL QUICKLY BURN OFF THIS AFTERNOON ALLOWING FOR
ANOTHER HOT AND MUGGY DAY. CHANCE OF RAIN TODAY WILL BE FAR LESS
THAN YESTERDAY. AT 250 MB BEST UPPER LEVEL DIFFLUENCE IS OFF TO
THE EAST OF THE AREA THANKS TO AN UPPER LEVEL RIDGE MOVING INTO
CENTRAL TEXAS. AT 500 MB HEIGHTS HAVE ALSO STARTED TO RISE ACROSS
SOUTHEAST TEXAS THANKS TO A BUILDING RIDGE. THE RAP PERFORMED
PRETTY WELL YESTERDAY AND SHOWS ALMOST NO RAIN FOR SOUTHEAST TEXAS
EXCEPT FOR A SPOTTY SHOWER OR TWO IN SAN JACINTO AND LIBERTY
COUNTIES LATER THIS AFTERNOON. THE TEXAS TECH WRF ALSO SHOWS THIS.
GIVEN THE EVIDENCE FROM THE UPPER LEVEL MAPS MENTIONED ABOVE THIS
MAKES SENSE.
THE UPPER LEVEL RIDGE WILL CONTINUE TO BUILD AND POSITION ITSELF
NEAR THE ARKANSAS/ LOUISIANA BORDER ON FRIDAY. THE HEAT ADVISORY
WILL LIKELY BE NEEDED THROUGH THE WEEKEND. BY SUNDAY THE RIDGE
WILL BEGIN TO WEAKEN. GFS FORECAST SOUNDINGS STILL SHOW RELATIVELY
LOW PWAT AIR IN PLACE FOR THIS TIME OF YEAR AND A CAP IN PLACE AT
850MB. ON MONDAY THE CAP WEAKENS ENOUGH TO INTRODUCE THE CHANCE OF
RAIN BACK INTO THE FORECAST. THE CHANCE OF AFTERNOON SHOWERS AND
THUNDERSTORMS AND ABOVE NORMAL TEMPERATURES LOOKS TO REMAIN IN
PLACE THROUGH NEXT WEDNESDAY. 23
&&
.MARINE...
MODERATE ONSHORE WINDS WILL PERSIST THROUGH TONIGHT AND BEGIN TO
RELAX BY FRIDAY MORNING. WILL MAINTAIN THE SCEC FOR THE GULF WATERS
THROUGH THE EARLY MORNING. SURFACE HIGH PRESSURE WILL BE CENTERED
OVER THE WESTERN GULF BY SUNDAY MORNING AND THE PRESSURE GRADIENT
WILL SLACKEN CONSIDERABLY. LIGHT WINDS ARE EXPECTED OVER THE WEEKEND
AND INTO THE FIRST HALF OF NEXT WEEK. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 77 99 77 99 / 10 10 10 10 10
HOUSTON (IAH) 97 77 97 77 97 / 10 10 10 10 10
GALVESTON (GLS) 92 84 92 84 92 / 20 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON...
MATAGORDA.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 7 AM CDT THIS MORNING
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM
FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS
FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH
ISLAND TO FREEPORT OUT 20 NM.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
240 AM EDT THU AUG 21 2014
.SYNOPSIS...
A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST
OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST
ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE
REGION EACH DAY. THE FRONT SHOULD SHIFT BACK SOUTH OF THE REGION
SATURDAY BRINGING A RETURN TO COOLER WEATHER FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 1120 PM EDT WEDNESDAY...
MLCAPES OVER 1500 J/KG STILL LINGERING OVER THE PIEDMONT LATE THIS
EVENING KEEPING CONVECTION ONGOING FROM THE NC/VA LINE NORTH INTO
BUCKINGHAM COUNTY. AIRMASS HAS BEEN WORKED OVER ACROSS THE
MTNS...AND DESPITE A STRONGER WAVE DEPICTED BY LATEST RAP ANALYSIS
OVER KY...NOT SEEING MUCH OF ANYTHING EXCEPT ISOLATED/WIDELY
SCATTERED SHOWER THREAT THROUGH 3 AM OUT OVER FAR SW VA INTO NW
NC. THINK THE CONVECTION OUT EAST WILL EXIT THE CWA BY 1 AM.
SKIES WILL BE VARIABLY CLOUDY WITH LOTS OF HIGH CLOUDINESS ACROSS
THE WEST AND SOUTH. CLEARING TAKES PLACE INTO EARLY MORNING OUT
EAST...WITH MORE CLOUDS ARRIVING INTO THE APPALACHIANS AHEAD OF
THE NEXT SHORTWAVE MOVING OVER ILLINOIS THIS EVENING. MODELS HAVE
SLOWED TIMING DOWN SOME WITH ONSET OF NEXT ROUND OF SHOWERS IN THE
MTNS...SO DELAYED CHANCES A COUPLE OF HOURS.
FOG MAY BE MORE OF AN ISSUE OUT EAST IF/WHEN IT CLEARS ESPECIALLY
WHERE IT RAINED. FOR NOW KEPT IN PATCHY FOG...WITH AREAS CLOSER TO
BUCKINGHAM COUNTY. LOW TEMPS REMAIN MUGGY IN THE 60S.
WEAK RESIDUAL FRONT WILL LIFT BACK NE ON THURSDAY AS THE WAVE CHANNEL
ALOFT AROUND THE RIDGE TO THE SW AMPLIFIES A BIT AND STARTS TO SHIFT
NORTH AS WELL. MODELS BRING ANOTHER IMPULSE QUICKLY SE OUT OF THE
UPSTREAM CONVEYER BELT AND DRIVE IT TOWARD THE NW COUNTIES
THURSDAY MORNING SIMILAR TO TODAY...PERHAPS JUST A BIT SLOWER.
HOWEVER LIFT WILL BE ENCOUNTERING DEEP NW FLOW SO UNCERTAIN AS TO
HOW FAR THIS COMPLEX MAY GET BEFORE FADING. THUS RUNNING WITH
INCREASING CHANCE POPS THURSDAY MORNING...MAINLY BLUE RIDGE
WEST...WITH HIGHEST ACROSS SE WEST VA. EXPECT EARLY CONVECTION TO
AGAIN FADE CROSSING THE RIDGES AS WE SLIP IN BETWEEN WAVES BEFORE
BETTER INSTABILITY/OUTFLOW HELPS REDEVELOP AT LEAST SCATTERED
AFTERNOON COVERAGE MOUNTAINS...AND ISOLATED OUT EAST WHERE
DOWNSLOPE ALOFT WILL BE STRONGER. THEREFORE TRIMMED BACK POPS TO
MORE CHANCE NATURE GIVEN TRENDS OF LATE AND LACK OF MUCH LIFT
THURSDAY AFTERNOON WITH THE NEXT WAVE IN OHIO. WARMING ALOFT AND
WESTERLY WINDS SHOULD COMBINE WITH SUNSHINE TO PUSH TEMPS ABOVE 90
SE WITH 80S MOST OTHER SPOTS PENDING EARLY CLOUDS.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 245 PM EDT WEDNESDAY...
FORECAST AREA STAYS IN BROAD NORTHWEST SYNOPTIC FLOW. PROBABILITY
OF PRECIPITATION WILL DEPEND ON WHEN SHORT WAVES COME THROUGH.
SHOWERS AND THUNDERSTORMS THAT CROSS THE COUNTY WARNING AREA
DURING THE LATE NIGHT OR EARLY MORNING...OR UPSTREAM CLUSTERS OF
STORMS THAT SPREAD CLOUDS DOWNSTREAM OVER US WILL DIMINISH THE
AVAILABLE INSTABILITY.
MODELS HAVE AXIS OF BEST LIFT SHIFTING JUST NORTH OF THE FORECAST
AREA ON FRIDAY. THIS MAY LIMIT THE COVERAGE OF PRECIPITATION FOR
FRIDAY THROUGH SATURDAY. BUT SURFACE BOUNDARY POSSIBLY MOVING SOUTH
THROUGH THE EASTERN PART OF THE FORECAST AREA ON FRIDAY MAY TRIGGER
SHOWERS AND THUNDERSTORMS. PRECIPITABLE WATER VALUES REMAIN HIGH
THROUGH THE PERIOD. LARGE RAINFALL RATES WILL BE POSSIBLE IN ANY OF
THE STORMS.
EXPECTING MUGGY CONDITIONS OVERNIGHT WITH DEW POINTS REMAINING WELL
INTO THE 60S. 850 TEMPERATURES ON THE EASTERN SIDE OF THE FORECAST
AREA WILL BE COOLER THAN IN THE WEST. OVERALL PRECIPITATION AND
CLOUD COVER WILL HOLD TEMPERATURES AT OR JUST BELOW NORMAL FOR
MAXIMUM TEMPERATURES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 300 PM EDT WEDNESDAY...
LARGE UPPER RIDGE BUILDS FROM THE LOWER MISSISSIPPI VALLEY. 500 MB
HEIGHTS OVER THE FORECAST AREA BEGIN TO RISE ON TUESDAY WITH THE
RIDGE CENTERED OVER THE TENNESSEE VALLEY.
SURFACE HIGH PRESSURE WILL BE OVER NEW ENGLAND AND WEDGED DOWN THE
APPALACHIANS THROUGH TUESDAY. BY THURSDAY A STRONG BERMUDA HIGH WILL
BE IN PLACE.
CHALLENGING TO TIME SHORT WAVES COMING OVER THE TOP OF THE RIDGE.
WPC WAS FAVORING A BLEND OF ENSEMBLE GFS AND ECMWF THROUGH THE
PERIOD. THIS KEEPS FORECAST AREA IN A PERSISTENT CHANCE OF
PRECIPITATION THROUGH MONDAY NIGHT. AT THIS TIME WILL BE
EMPHASIZING SUNDAY NIGHT AS THE BEST CHANCE IN THIS TIME FRAME.
WILL BE WARMING UP CLOSER TO ABOVE NORMAL TEMPERATURES ASSOCIATED
WITH THE UPPER RIDGE ON WEDNESDAY.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 230 AM EDT THURSDAY...
PATCHY MORNING FOG ANTICIPATED AREAWIDE...MAINLY MVFR...BUT CAN`T
RULE OUT BRIEF PERIOD OF IFR/LIFR FOR A FEW HOURS AROUND DAYBREAK.
ANY FOG AND STRATUS THAT FORMS WILL DISSIPATE AFTER SUNRISE WITH
WIDESPREAD VFR CONDITIONS DEVELOPING AFTER 13Z/9AM.
SHALLOW EASTERLY SURFACE WINDS THIS MORNING WILL GIVE WAY TO WEST
NORTHWEST WINDS LATER THIS MORNING. THE LOW LEVEL FLOW WILL BE
FROM THE NORTHWEST TODAY...WINDS 6-12 KTS...AND GUSTY NEAR THE
RIDGE CRESTS. THE DEEPER FLOW...WELL ALOFT...IS ALSO FROM THE
NORTHWEST. THIS WILL TRANSPORT DEBRIS CLOUDINESS DOWNSTREAM FROM
THUNDERSTORMS OVER THE MIDWEST AND OHIO VALLEY REGIONS...CLOUD
LAYERS MAINLY ABOVE 10KFT.
WITH WINDS OUT OF THE WEST TODAY...THIS WILL CREATE DOWNSLOPE
COMPRESSIONAL WARMING AND SUBSIDENCE. DO NOT EXPECT MUCH IN THE
WAY OF LOCAL STORM ACTIVITY...DEEP CONVECTION...DUE TO THIS
DOWNWARD VERTICAL MOTION. THE SUBSIDENCE IS EXPECTED TO WEAKEN
TOWARD SUNSET...THUS POTENTIAL FOR STORM ACTIVITY WILL
INCREASE...BUT MAINLY CONFINED LATER IN THE TAF PERIOD.
THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY VCNTY OF STALLED
FRONTAL BOUNDARY OVER THE OHIO VALLEY. STORMS WHICH DEVELOP VCNTY
OF THIS BOUNDARY...ACROSS IL/IN/OH/KY...WILL MOVE DOWNSTREAM
TOWARD THE MID ATLANTIC REGION THIS EVENING AND DURING THE
OVERNIGHT TONIGHT.
HIGHEST CONFIDENCE FOR STORMS THIS AFTERNOON WILL BE FROM WEST
VIRGINIA INTO THE OHIO VALLEY...THE THREAT TRANSITIONING
DOWNSTREAM INTO VIRGINIA AND NORTH CAROLINA TONIGHT. INTRODUCED
VCNTY TSRA FOR ALL THE TERMINALS AFTER 22Z/6PM...THE STORM THREAT
PERSISTING THROUGH THE OVERNIGHT. CONFIDENCE IS HIGHER FOR THE WV
TERMINALS.
EXTENDED AVIATION...
UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY AND
INTERACTING WITH A STATIONARY FRONT OVER THE AREA FOR THE NEXT FEW
DAYS...RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS. DUE TO
THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND FOG
DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST
PRONOUNCED BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED
THAT A DEEPER EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS
UPCOMING WEEKEND. THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN
DURING THE DAYTIME PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD
MVFR CONDITIONS ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE
BANKING UP AGAINST THE EAST SIDE OF THE APPALACHIANS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/WP
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...PM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1149 PM CDT WED AUG 20 2014
.UPDATE...
ISSUED AT 844 PM CDT WED AUG 20 2014
THE MAIN FOCUS CONTINUES TO BE ON THE CONVECTIVE TRENDS FOR THE
OVERNIGHT PERIOD AS THE LOW LEVEL JET STRENGTHENS INTO THE UPPER
MISSISSIPPI RIVER VALLEY REGION. AN INITIAL BAND OF LIGHT RAIN
SHOWERS HAS DEVELOPED ACROSS SOUTHWEST MINNESOTA AND NORTH CENTRAL
IOWA ALONG THE LEADING/EASTERN EDGE OF THE LOW LEVEL MOISTURE
TRANSPORT/WARM AIR ADVECTION WING. THESE SHOWERS HAVE BEEN VERY
LIGHT AND ARE NOT EXPECTED TO STRENGTHEN IN INTENSITY THROUGH THE
LATE EVENING HOURS.
THE MAIN FOCUS IS FURTHER WEST UNDER THE MAIN CORRIDOR OF BETTER
LOW LEVEL MOISTURE TRANSPORT THAT IS PUSHING UP INTO EASTERN SOUTH
DAKOTA AND FAR SOUTHWESTERN MINNESOTA. CONVECTION IS STARTING TO
DEVELOP ACROSS THIS CORRIDOR AND WILL INCREASE IN COVERAGE AND
TRACK EAST OVERNIGHT. THE PAST FEW RUNS OF THE HRRR SEEM TO BE
CATCHING UP TO THE CURRENT CONDITIONS AND SHOWING THIS TREND
BETTER WITH THE MAIN BATCH OF RAIN/CONVECTION COMING THROUGH
AROUND DAYBREAK TOMORROW MORNING. THEREFORE...HAVE BACKED OFF ON
PRECIPITATION CHANCES THROUGH THIS EVENING AND FOCUSED THEM MORE
ON THE EARLY MORNING HOURS ON THURSDAY. THE 21.00Z RAP SHOWS THE
MAIN BELT OF ELEVATED INSTABILITY RUNNING FROM EASTERN IOWA INTO
SOUTH CENTRAL SOUTH DAKOTA WITH A GRADUAL SHIFT NORTHWARD OF IT
OVERNIGHT. THE TREND IS FOR THIS INSTABILITY TO CONTINUALLY WEAKEN
AS THE NIGHT PROGRESSES WITH AROUND 1000 J/KG OF 0-3KM MUCAPE LEFT
BY DAYBREAK. WITH THE INCREASING LIFT THANKS TO THE LLJ...STILL
CAN NOT RULE OUT THAT A FEW OF THE STORMS COULD BECOME
STRONGER...BUT THE THREAT OF WIDESPREAD STRONG TO SEVERE WEATHER
APPEARS LOW.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 218 PM CDT WED AUG 20 2014
PRIMARY FORECAST CHALLENGE WILL BE SHOWER AND THUNDERSTORM TIMING
AND COVERAGE TONIGHT THROUGH THURSDAY AND THE POTENTIAL FOR
LOCALIZED FLOODING. CONVECTIVE CHANCES WILL CONTINUE TO BE A
CONCERN FRIDAY THROUGH THE WEEKEND AS WELL. HIGH RESOLUTION MODELS
BEGINNING TO CONVERGE ON A SOLUTION TONIGHT WHICH MATCHES WELL
WITH SYNOPTIC/MESOSCALE SIGNALS IN GLOBAL MODEL SUITE. WILL USE A
BLENDED MODEL SOLUTION WITH A SLIGHT PREFERENCE TOWARD THE ECMWF/
NAM AS THE GFS IS A BIT FASTER/FARTHER NORTH WITH FRONTAL PASSAGE
TOMORROW.
20.20Z SURFACE ANALYSIS SHOWS A LOW PRESSURE CENTER ACROSS
SOUTHWEST NE WITH ITS WARM FRONT DRAPED TO THE EAST ACROSS
SOUTHERN NE INTO NORTHWEST MO. ACTUAL CONVECTION HAS BEEN FURTHER
NORTH AND EAST ACROSS CENTRAL IA COINCIDENT WITH BEST MID-LEVEL
WARM AIR ADVECTION...MOISTURE CONVERGENCE AND ISENTROPIC LIFT.
SURFACE LOW IS PART OF A MUCH BROADER TROUGH THAT WILL SLOWLY LIFT
NORTH AND EAST TONIGHT THROUGH THURSDAY PLACING THE SURFACE WARM
FRONT ACROSS THE SOUTHERN FORECAST AREA BY 21.12Z. EXPECT A
NORTHWEST TO SOUTHEAST ORIENTED LINE OF CONVECTION TO DEVELOP LATE
THIS EVENING AHEAD OF THE FRONT AND MOVE NORTHEASTWARD ALIGNED
ALONG OR JUST NORTH OF THE MISSISSIPPI RIVER VALLEY BY DAYBREAK
THURSDAY.
ELEVATED CAPE OVERNIGHT GENERALLY REMAINS LESS THAN 1000
J/KG...BUT 0 TO 6 KM BULK SHEAR INCREASES TO NEAR 40 KTS BY 21.12Z
WITH IMPINGING 300 HPA JET STREAK. NOT EXPECTING WIDESPREAD
SEVERE...BUT COULD SEE SOME ISOLATED LARGE HAIL OR DAMAGING WIND
FROM THE STRONGEST STORMS. BIGGER CONCERN WILL BE HEAVY RAIN.
EXPECT STRONG MID-LEVEL MOISTURE TRANSPORT WITH PRECIPITABLE WATER
VALUES INCREASING TO NEAR 2.0 INCHES. SEE HYDROLOGY DISCUSSION FOR
MORE DETAILS.
20.12Z ECMWF/NAM SUGGEST WARM FRONT MAY STALL THURSDAY AFTERNOON
NEAR THE MISSISSIPPI RIVER VALLEY...RESULTING IN A PROLONGED
PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS WESTERN/CENTRAL WI.
INCREASED POPS IN THESE AREAS THROUGH THE AFTERNOON AND LOWERED
TEMPERATURES A HANDFUL OF DEGREES. SOUTH OF THE FRONT WILL WARM
NICELY WITH TEMPERATURES RISING INTO THE UPPER 80S TO NEAR 90
DEGREES.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 218 PM CDT WED AUG 20 2014
MAIN SURFACE TROUGH WILL SWEEP ACROSS THE FORECAST AREA THURSDAY
NIGHT...RESULTING IN DECREASING CONVECTION AND DRYING FROM WEST
TO EAST. HOWEVER...REGION WILL REMAIN IN WARM MOIST AIR MASS
RESULTING IN HIGH TEMPERATURES FRIDAY CLIMBING INTO THE MID TO
UPPER 80S WITH DEW POINT TEMPERATURES INTO THE LOWER 70S.
HARD TO PINPOINT A PROLONGED DRY PERIOD SATURDAY THROUGH WEDNESDAY.
500 HPA RIDGE BUILDS ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
WITH ITS AXIS SLIDING SLOWLY TO THE EAST THROUGH THE WEEK
RESULTING IN INCREASED SOUTHWEST FLOW ALOFT. A SERIES OF ILL-
RESOLVED EMBEDDED SHORT WAVES COMBINED WITH A WAVERING SURFACE
BOUNDARY WILL PROVIDE THE FOCUSING MECHANISMS FOR CONVECTION...
BUT TIMING AND COVERAGE UNCERTAINTY ABOUNDS. THIS ALSO WRECKS
HAVOC ON SEVERE POTENTIAL AND WILL NEED TO MONITOR SUBSEQUENT
MODEL RUNS. WILL FOLLOW ALL BLEND POPS FOR NOW HIGHLIGHTING 20 TO
50 PERCENT CHANCES FOR MEASURABLE RAIN EACH PERIOD.
TEMPERATURES THROUGH SUNDAY WILL REMAIN ON THE HIGH SIDE OF NORMAL
WITH DAILY HIGHS IN THE MID TO UPPER 80S AND POSSIBLY EVEN BREACHING
90 DEGREES GIVEN 925 HPA TEMPERATURES RANGING FROM 22 TO 27 C.
COULD SEE SOME RELIEF MONDAY/TUESDAY AS PRIMARY EASTERN PACIFIC
TROUGH ATTEMPTS TO MAKE SOME HEADWAY INTO STUBBORN UPPER LEVEL
RIDGE ACROSS THE GREAT LAKES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1149 PM CDT WED AUG 20 2014
CONFIDENCE CONTINUES TO DECLINE IN WHETHER ANY CONVECTION WILL
OCCUR OVERNIGHT AS THE MAIN FOCUS CONTINUES TO BE WELL OFF TO THE
WEST CLOSER TO LOW IN THE DAKOTAS. SOME VERY LIGHT RAIN SHOWERS
HAVE BEEN SHOWING UP ACROSS SOUTH CENTRAL MINNESOTA AND NORTH
CENTRAL IOWA BUT HAVE STRUGGLED TO MAKE IT EAST INTO THE REGION.
HAVE BACKED OFF ON THE AMOUNT OF CONVECTION IN THE TAFS AND
BROUGHT THE MAIN CHANCES IN AROUND OR AFTER DAYBREAK THURSDAY
MORNING. CONFIDENCE IS FAIRLY LOW WITH HOW THINGS WILL EVOLVE
BEYOND THAT INTO THURSDAY AFTERNOON AND EVENING...BUT IT SEEMS
THAT THE FOCUS SHOULD BE TO THE NORTHEAST OF THE TAF SITES.
&&
.HYDROLOGY...
ISSUED AT 218 PM CDT WED AUG 20 2014
URBAN AND SMALL STREAM FLOODING AND/OR LOCALIZED FLASH FLOODING IS
POSSIBLE TONIGHT THROUGH THURSDAY GIVEN MODEST FORCING IMPINGING
ON A VERY MOIST AIR MASS. PRECIPITABLE WATER VALUES NEAR 2.0
INCHES ARE NEAR THE 99TH PERCENTILE OF THE CLIMATOLOGICAL NORMAL
AT KMPX/KDVN. WARM CLOUD DEPTHS ARE ALSO VERY DEEP...WHICH SHOULD
RESULT IN EFFICIENT WARM RAIN PROCESSES. EVEN WITH RECENT RAINFALL...
REGIONAL SOILS ARE STILL RELATIVELY DRY AND SHOULD BE ABLE TO
ABSORB HEAVY RAINFALL UNLESS RATES BEGIN TO EXCEED 2 INCHES/HOUR
PER LATEST FLASH FLOOD GUIDANCE. CERTAINTY IN WIDESPREAD FLOODING
RAINS NOT HIGH ENOUGH AT THIS TIME TO WARRANT A FLASH FLOOD
WATCH...BUT FUTURE SHIFTS WILL NEED TO MONITOR THIS POTENTIAL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
UPDATE...HALBACH
SHORT TERM...ROGERS
LONG TERM....ROGERS
AVIATION...HALBACH
HYDROLOGY....ROGERS
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1107 PM MDT WED AUG 20 2014
.UPDATE...
ISSUED AT 846 PM MDT WED AUG 20 2014
MIDLVL MOISTURE PLUME CONTINUES TO STREAM NORTHWARD ACROSS THE CWA
THIS EVE PER LATEST WATER VAPOR SAT. THIS HAS ALLOWED SHOWERS AND
TSTMS TO PERSIST ACROSS PARTS OF THE AREA WELL INTO THE EVE. KCYS
RADAR LOOP SHOWS TWO SEPARATE AREAS OF PCPN LIKELY IN ASSOCIATION
WITH TWO DISTINCT SHORTWAVES EMANATING FROM THE UPPER LOW SPINNING
OVER SOUTHERN CA. THESE AREAS ARE THE HIGHER TERRAIN OUT WEST OVER
CARBON AND ALBANY COUNTIES...AND AREAS EAST OF I25 ALONG THE I80
CORRIDOR ACROSS WESTERN NE. HRRR TRENDS HAVE HINTED AT CONVECTION
CONTINUING BEYOND 06Z OVER THE SOUTHERN PANHANDLE. ADDED POPS THRU
06Z WITH GOOD MOISTURE IN PLACE...BUT SHOWERS SHOULD BE DECREASING
IN COVERAGE BY THEN. THE REST OF THE INHERITED FCST IS IN GOOD
SHAPE THIS EVE.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 330 PM MDT WED AUG 20 2014
CURRENT KCYS RADAR LOOP SHOWS SHOWERS AND FEW THUNDER SHOWERS
DEVELOPING OVER THE MOUNTAINS AND THE CHEYENNE RIDGE THIS
AFTERNOON...AND SLOWLY MOVING EASTWARD. ACTIVITY HAS BEEN WEAK
WITH ONLY A FEW ISOLATED LIGHTNING STRIKES. EXPECT THIS ACTIVITY
TO CONTINUE THROUGH INTO LATE THIS AFTERNOON AND EARLY THIS
EVENING WHILE DEVELOPING FURTHER EAST INTO THE HIGH PLAINS OF
SOUTHEAST WYOMING. EXPECT ANY THUNDERSTORMS TO QUICKLY DIMINISH
AROUND SUNSET.
THUNDERSTORM COVERAGE WILL LIKELY BE LOWER ON THURSDAY ACROSS MOST
OF THE FORECAST AREA AS WARMER AIR ALOFT MOVES INTO THE AREA AND
500MB HEIGHTS INCREASE THROUGH THE DAY. A COLD FRONT BOUNDARY WILL
BECOME MORE NOTICEABLE FURTHER NORTH ACROSS MONTANA AND NORTHERN
WYOMING AS IT SLOWLY DRIFTS SOUTHWARD THROUGH THE DAY.
THEREFORE...EXPECT THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS
TO BE ACROSS THE MOUNTAINS AND WELL NORTH OF I80. CAN NOT RULE OUT
A THUNDER SHOWER OR TWO ALONG THE I80 CORRIDOR DURING THE EVENING
HOURS. TEMPERATURES WILL REMAIN NEAR NORMAL AND GENERALLY IN THE
UPPER 70S WEST OF THE LARAMIE RANGE AND LOW 80S TO LOW 90S ACROSS
THE EASTERN PLAINS.
THIS PERSISTENT WEATHER PATTERN WILL BEGIN TO CHANGE ON FRIDAY AND
ESPECIALLY THIS WEEKEND. MODELS INDICATE A PRETTY STRONG COLD
FRONT FOR THIS TIME OF THE YEAR PUSHING SOUTHWARD INTO SOUTHEAST
WYOMING. THIS FRONT WILL STALL SOMETIME ON FRIDAY AND BE THE MAIN
FOCUS FOR SCATTERED TO NUMEROUS SHOWERS AND TSTORMS AS AN UPPER
LEVEL TROUGH FROM WESTERN CANADA MOVE SOUTH AND EVENTUALLY
EASTWARD INTO IDAHO. LOWERED MAX AND MIN TEMPERATURES FRIDAY AND
FRIDAY NIGHT AND INCREASED POP BETWEEN 25 TO 45 PERCENT ACROSS THE
HIGH PLAINS...AND NEAR 70 PERCENT OVER THE MOUNTAINS.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 330 PM MDT WED AUG 20 2014
BOTH THE GFS AND ECMWF BRING A SHORTWAVE THROUGH THE AREA IN
SOUTHWEST WIND FLOW FRIDAY NIGHT INTO SATURDAY. ECMWF ROUGHLY 12
HOURS SLOWER THAN THE GFS...BUT BOTH ARE IN CLOSE AGREEMENT WITH
MOVEMENT OF FIRST DISTURBANCE...THEN MOVING THE MAIN TROUGH
THROUGH ON SATURDAY/SATURDAY NIGHT. JUST ABOUT EVERYONE SHOULD SEE
SHOWERS/THUNDERSTORMS DURING THE DAY SATURDAY WITH BEST CHANCES
FOR THE PANHANDLE SATURDAY NIGHT. MAIN SHORTWAVE THROUGH THE AREA
BY SUNDAY...WITH MAINLY ISOLATED SHOWERS OVER THE MOUNTAINS.
NEXT COLD FRONT LOOKS TO MOVE INTO THE AREA MONDAY AFTERNOON INTO
TUESDAY. ECMWF A LITTLE COLDER THAN GFS IN 700MB
TEMPERATURES...BUT NOT AS BAD AS A FEW DAYS AGO. PROBABLY NEED TO
GO COLDER WITH THIS SETUP. DISCREPANCY MUCH GREATER ON TUESDAY
WITH THE ECMWF FORECASTING 700MB TEMPERATURES OF +4 TO +6C AND GFS
SHOWING +10 TO +12C.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 1104 PM MDT WED AUG 20 2014
A FEW LINGERING SHOWERS AND THUNDERSTORMS AS OF 5Z WILL MOSTLY DIE
OFF IN THE NEXT FEW HOURS. OUTSIDE ANY SHOWER OR THUNDERSTORM
ACTIVITY...VFR WILL OCCUR THROUGH THE TAF PERIOD. WINDS WILL
GENERALLY REMAIN LIGHT THROUGH THURSDAY BUT SOME GUSTS TO 25 MPH
CAN BE EXPECTED THURSDAY AFTERNOON ALONG AND WEST OF THE LARAMIE
RANGE. A FEW THUNDERSTORMS WILL BE POSSIBLE THURSDAY AFTERNOON AND
EARLY EVENING.
&&
.FIRE WEATHER...
ISSUED AT 156 PM MDT WED AUG 20 2014
MINIMAL FIRE WEATHER CONCERNS INTO EARLY NEXT WEEK. SUBTROPICAL
MOISTURE WILL REMAIN OVER THE AREA THROUGH THE WEEKEND WITH
SHOWERS AND THUNDERSTORMS POSSIBLE EACH DAY ACROSS SOUTHEAST
WYOMING AND WESTERN NEBRASKA. THERE IS A GOOD CHANCE OF WETTING
RAINS BY FRIDAY AND THIS WEEKEND AS THUNDERSTORM COVERAGE WILL BE
HIGHER. TEMPERATURES WILL TREND COOLER BY LATE THIS WEEK AND INTO
THIS WEEKEND AS A STRONG COLD FRONT FOR THIS TIME OF THE YEAR
MOVES INTO THE REGION LATE ON SATURDAY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...HAMMER
SHORT TERM...TJT
LONG TERM...CLAYCOMB
AVIATION...SML
FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
357 AM PDT THU AUG 21 2014
.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL SLOWLY MOVE EAST OVER
EXTREME SOUTHERN CALIFORNIA THURSDAY. THERE IS A VERY SMALL CHANCE
OF AN ISOLATED SHOWER OR THUNDERSTORM TONIGHT AND EARLY THURSDAY
OVER MOST AREAS...THEN THE CHANCE OF THUNDERSTORMS WILL BE PRIMARILY
OVER THE MOUNTAINS AND DESERTS BY THURSDAY AFTERNOON. TEMPERATURES
WILL CONTINUE TO BE BELOW NORMAL THURSDAY. AFTER THE LOW EXITS TO
THE EAST THURSDAY NIGHT...THERE WILL BE DRY AND WARMER WEATHER
FRIDAY FOLLOWED BY SLIGHT COOLING OVER THE WEEKEND. HIGH PRESSURE
ALOFT WILL BUILD NEXT WEEK AND BRING A WARMING TREND.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THE CLOSED UPPER LOW IS LOCATED JUST WEST OF SAN DIEGO EARLY THIS
MORNING AND CONTINUES TO WOBBLE SOUTH BUT IS ALSO BEGINNING TO
MOVE TO THE EAST ATTM. ALL OF THE SHORT RANGE MODELS SHIFT THE
CLOSED LOW TO THE EAST LATER TODAY AS IT GETS PICKED UP BY THE
WESTERLIES...ACCELERATING IT EAST TO CENTRAL ARIZONA BY THIS TIME
FRIDAY. FOR TODAY THE UPPER LOW SHOULDN`T HAVE MUCH OF AN IMPACT
ON COASTAL SOCAL AT THIS POINT AS WE ARE QUICKLY GOING TO BE ON
THE BACKSIDE OF THE LOW. HOWEVER THE UPPER CIRCULATION WILL BE
INTERACTING WITH THE DIURNAL HEATING OF OUR MOUNTAIN AND DESERT
REGIONS AND WILL HELP TO KICK OFF ANOTHER ROUND OF CONVECTION IN
THOSE AREAS...PROBABLY AS QUICKLY AS MIDDAY OR EARLY AFTERNOON.
MODEL SURFACE CAPE IS FORECAST TO REACH 1000+ J/KG ACCORDING TO
THE LATEST 3KM HRRR AND THE HIGH RES NAM AS WELL. MOISTURE PROGS
ARE SHOWING SOME MOISTURE ADVECTION TO THE MOUNTAIN AND DESERT
AREAS ALTHOUGH NOT SIGNIFICANTLY ABOVE NORMAL VALUES WITH MODEL
SOUNDINGS SHOWING PWAT VALUES INCREASING FROM ABOUT 3/4 OF AN INCH
TO A LITTLE OVER 1 INCH IN THE SAN DIEGO COUNTY MOUNTAINS THIS
AFTERNOON. WITH THIS IN MIND WE BELIEVE THERE WILL BE A MODERATE
FLASH FLOOD POTENTIAL COINCIDENT WITH LIKELY POPS IN THE MOUNTAIN
AREAS (EXCEPT ORANGE COUNTY MOUNTAINS).
FOR TONIGHT THE CONVECTION SHOULD QUICKLY DIMINISH WITH THE LOSS
OF HEATING. LIGHT ONSHORE FLOW WILL ALLOW THE MARINE LAYER TO
DEEPEN ALONG THE COAST BUT INTRUSION SHOULD BE LIMITED TO THE NEAR
COASTAL AREAS TONIGHT AND AT LEAST A PORTION OF THE COASTAL
VALLEYS. DIURNAL MARINE INTRUSIONS SHOULD CONTINUE THROUGH THE
WEEKEND BUT NOT PARTICULARLY DEEP.
LOW CONFIDENCE IN THE SYNOPTIC PATTERN THROUGH MID NEXT WEEK AS
SOLUTIONS DIVERGE ON WHETHER A TROUGH WILL DROP OUT OF THE PACNW
AND AFFECT SOCAL. ALSO MOISTURE FROM TWO TROPICAL SYSTEMS...KARINA
AND LOWELL...WILL HAVE THE POTENTIAL TO ADVECT INTO OUR REGION
FOR THE NEXT SEVERAL DAYS ALTHOUGH I`VE NOT SCENE A SOLUTION THAT
ACTUALLY BRINGS MUCH MOISTURE THAT FAR NORTH AT THIS TIME.
SOMETHING TO KEEP AN EYE ON ANYWAY.
&&
.AVIATION...
211000Z...PATCHY STRATUS...WITH BASES 1600-2100 FT MSL AND TOPS NEAR
2400 FT MSL...WILL CONTINUE TO DEVELOP OVER THE SAN DIEGO COUNTY
VALLEYS AND COAST...AND OVER PORTIONS OF ORANGE COUNTY BY SUNRISE
THIS MORNING. VISIBILITY WILL LOWER TO 1-3 SM DUE TO MIST AND FOG
WHERE STRATUS NEARS HIGHER TERRAIN. LOW CLOUDS WILL CLEAR TOWARDS
THE COAST LATE THIS MORNING...THEN REDEVELOP ALONG THE COAST LATE
THIS EVENING. ISOLATED SHOWERS AND THUNDERSTORMS...WITH BASES AROUND
8000 FT MSL AND TOPS TO 35000 FT MSL...WILL BE POSSIBLE ACROSS THE
REGION THIS MORNING...THEN MAINLY ACROSS THE MOUNTAINS AND DESERTS
THIS AFTERNOON. GUSTY WINDS...STRONG UP/DOWNDRAFTS...SMALL HAIL AND
LIGHTNING WILL BE POSSIBLE NEAR STORMS. FORECASTER CONFIDENCE IS
MEDIUM.
&&
.MARINE...
200 AM...NO MARINE WEATHER HAZARDS ARE EXPECTED THROUGH MONDAY.
&&
.BEACHES...
.BEACHES...
A 4 TO 5 FOOT...12 SECOND SOUTHERLY SWELL WILL CREATE ELEVATED SURF
AND STRONG RIP CURRENTS ALONG THE SAN DIEGO AND ORANGE COUNTY COAST
THROUGH THIS WEEKEND. SURF OF 3 TO 5 FEET IS EXPECTED...WITH SETS TO
7 FEET POSSIBLE ALONG SOUTHERLY FACING BEACHES. ELEVATED SURF AND
STRONG RIP CURRENTS WILL CREATE DANGEROUS SWIMMING CONDITIONS. A
BEACH HAZARD STATEMENT FOR ELEVATED SURF AND STRONG RIP CURRENTS IS
IN EFFECT FROM THIS MORNING THROUGH SUNDAY AFTERNOON.
&&
.SKYWARN...
SKYWARN ACTIVATION MAY BE REQUESTED LATER TODAY FOR THUNDERSTORMS
IN THE MOUNTAINS AND DESERTS. WEATHER SPOTTERS ARE ENCOURAGED TO
REPORT SIGNIFICANT WEATHER CONDITIONS.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...BEACH HAZARDS STATEMENT FROM 9 AM PDT THIS MORNING THROUGH
SUNDAY AFTERNOON FOR THE ORANGE COUNTY COASTAL AREAS...SAN
DIEGO COUNTY COASTAL AREAS.
PZ...NONE.
&&
$$
PUBLIC...BROTHERTON
AVIATION/MARINE...JJT
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1015 AM CDT Thu Aug 21 2014
.UPDATE...
ISSUED AT 1015 AM CDT THU AUG 21 2014
15z/10am surface analysis shows warm front extending from northern
Iowa to southern Lake Michigan. Numerous showers and thunderstorms
have been tracking along this boundary early this morning, mainly
impacting locations along/north of the I-80 corridor. This is a
bit further north than previously forecast, thanks to the upper
ridge building across the region. 12z NAM keeps central Illinois
dry throughout the day, then develops nocturnal convection as far
south as the I-72 corridor late tonight. NAM was too aggressive
with the southward extent of precip last night, so am skeptical
of its latest solution. HRRR is also dry through the day, and
does not develop any convection across the area through 03z this
evening. Based on latest satellite/radar trends and NAM/HRRR data,
have trimmed PoPs today and tonight. Will maintain slight chance
for showers/thunder across the far N and E CWA through the
morning, then will go with dry conditions across the board this
afternoon. Have also reduced PoPs for tonight, focusing highest
chances across the north from the Peoria and Bloomington areas
northward after midnight. With a good deal of sunshine and
southwesterly winds, afternoon highs will reach the upper 80s and
lower 90s.
&&
.SHORT TERM...(Today and Tonight)
ISSUED AT 342 AM CDT THU AUG 21 2014
Warm front has lifted north through most of the area and based on
surface observations, looks to be just north of I-74 at this point.
Believe the front will continue to lift north through the day,
resulting in the whole CWA being in the warm sector for the end of
the week. However, the mid level ridge will be somewhat flat and any
disturbance or wave that moves along the top of the ridge could
result in precip dropping into the northern and northeastern part of
the CWA. So chance pops will continue to be warranted over parts of
the CWA today and tonight. Pops will be less during the daytime
hours but then increase over the northeastern half of the CWA for
the overnight hours, tonight. Temperatures will be warm today, but
cloud cover could keep afternoon highs from getting too high, though
still expecting highs around 90 today. Lows tonight will be similar
to now, just about 1-2 degrees warmer.
&&
.LONG TERM...(Friday through Wednesday)
ISSUED AT 342 AM CDT THU AUG 21 2014
Summer heat continues through the remains of the weekend. Hot and
humid conditions lending to an isolated thunderstorm threat through
the weekend, particularly towards the NE as waves push over the
upper ridge building into the Midwest. Models shifting with each
issuance as to the actual increased threat with the erosion of the
ridging to the NE. Heat and humidity has been more consistent,
though even that has seen some shifts, starting to retract some of
the eastward creep of the 850 mb temps. Not pulling back too much
in the way of guidance just yet and temps Fri-Sun still in the 90s,
heat indices over 100F. Issuance of a Heat Advisory covered
above...however, should the dwpts materialize, or see the temps
respond as expected behind this mornings warm front today... will
rethink the issuance of a Heat Advisory for the weekend as these
temps are not only well above normal, but more impactful after such
a mild summer so far. Into the extended, day 6/just into day 8,
models have gone back to a divergence in solutions as the GFS is
more progressive with the next upper trof moving a cold front
through with storms and cooler temps in the wake...while the 00Z
ECMWF is now cutting off the low over the NW, extending the ridges
hold over the region.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 626 AM CDT THU AUG 21 2014
The warm front has lifted north of all the TAF sites and all pcpn
has moved north or east of the sites this morning. So most of the
day all sites will be pcpn free. So, there will be some high CU/SC
today with some cirrus early and then maybe some AC later this
morning. Then by this afternoon, skies should become scattered.
Clouds will then be on the increase around midnight as a complex
of storms will develop west of the area and move along the warm
front tonight. This should bring broken AC clouds to SPI and DEC,
but VCTS and broken SC/CU at PIA/BMI/CMI. Winds will be southwest,
but become southerly this evening for a brief time, then back to
southwest around midnight. Wind speeds will be around 7-10kts
through the period.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...AUTEN
LONG TERM...HJS
AVIATION...AUTEN
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1142 AM EDT THU AUG 21 2014
.SYNOPSIS...
ISSUED AT 152 AM EDT THU AUG 21 2014
PERIODIC SHOWERS AND THUNDERSTORMS ARE POSSIBLE INTO FRIDAY AS A
WARM FRONT SLOWLY MOVES NORTH INTO THE AREA. HEAT AND HUMIDITY
WILL RETURN BY FRIDAY AS THIS FRONT MOVES NORTH. HIGHS TODAY WILL
BE IN THE LOWER TO MID 80S. LOWS THE NEXT SEVERAL NIGHTS WILL BE
AROUND 70. HIGHS THIS WEEKEND WILL BE AROUND 90 DEGREES.
&&
.UPDATE...
ISSUED AT 1128 AM EDT THU AUG 21 2014
BROAD ISENTROPIC LIFT/LOW LEVEL MOISTURE TRANSPORT WILL CONTINUE
THROUGH THIS AFTERNOON FROM THE MID MS RIVER VALLEY EXTENDING
EASTWARD TO THE OHIO RIVER VALLEY. RUC INITIALIZATION SUPPORT
CONVECTIVE ENHANCEMENT TO SMALL SCALE VORT MAX TRACKING ACROSS
SOUTH/SOUTHEAST PORTIONS OF THE AREA THIS MORNING...WITH SOME
INDICATIONS OF MCV HAVING ALSO FORMED ACROSS FAR NORTH CENTRAL
INDIANA. A BRIEF LULL IN PRECIP IS POSSIBLE IN WAKE OF THIS
FEATURE OVER NEXT FEW HOURS...BUT A STEADY STREAM OF SMALLER SCALE
WAVES EMBEDDED IN NORTHWEST UPPER FLOW AND POOLED LOW LEVEL
MOISTURE AXIS ACROSS MUCH OF LOCAL AREA WILL SUPPORT AT LEAST
CHANCE TSRA MENTION THROUGH THE REMAINDER OF THE AFTERNOON.
SLIGHTLY MORE STABLE CONDITIONS ASSOCIATED WITH MORNING
CLOUDS/PRECIP MAY TEMPER SEVERE THREAT AT LEAST THROUGH MUCH OF
THE AFTERNOON HOURS. POCKET OF STRONGER MID/UPPER FLOW IS EXPECTED
TO OVERSPREAD THE AREA THIS EVENING AND THIS MAY SUPPORT SOUTHEAST
PROPAGATION OF POTENTIAL CONVECTIVE SYSTEM FORMING UPSTREAM OF
LOCAL AREA TONIGHT. RADAR ESTIMATES THAT MANY LOCATIONS FROM
WESTERN STARKE COUNTY INTO GRANT COUNTY HAVE EXPERIENCED 1 TO 2
INCHES OF RAINFALL WITH MORNING STORMS...AND SOME HYDRO CONCERNS
MAY EVOLVE TONIGHT DEPENDING ON UPSTREAM LATE AFTERNOON/EVENING
CONVECTIVE EVOLUTION...BUT WILL HOLD OFF ON ANY HYDRO HEADLINES AT
THIS TIME.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 449 AM EDT THU AUG 21 2014
UPPER LEVEL JET DYNAMICS COMBINED WITH THE LEADING EDGE OF THETA E
CONVERGENCE WAS HELPING TO TRIGGER ISOLATED STORMS AND AN AREA OF
SHOWERS NORTH OF THE FRONT. THE STORMS WERE HIGH BASED EARLY THIS
MORNING...BUT SHOULD BECOME MORE SURFACE BASED AS THE FRONT MOVES
NORTH AND AS THE ATMOSPHERE DESTABILIZES WITH DAYTIME HEATING LATER
TODAY. THETA E FLUX WILL INCREASE TONIGHT...WITH A BETTER CHANCE FOR
SHOWERS AND STORMS AS AN UPPER LEVEL DISTURBANCE TOPS THE UPSTREAM
RIDGE AND MOVES INTO THE WESTERN GREAT LAKES REGION. THE 12KM NAM
APPEARED TO HAVE A REASONABLE HANDLE ON THE TIMING OF THIS UPSTREAM
SYSTEM AND THE TRACK OVER THE UPPER LEVEL RIDGE...SO HAVE LIKELY
THUNDERSTORM CHANCES LATER TONIGHT. SEVERE STORMS ARE POSSIBLE GIVEN
DEEP LAYER SHEAR TOPPING OUT AT 30 TO 40 KNOTS. HAVE RAISED HIGHS
TODAY. THE NAM/MET HAS RAISED HIGHS TODAY 5 DEGREES AT SBN AND
APPEARS ON TRACK...COMING MORE IN LINE WITH THE GFS/MAV. 850 MB
TEMPS WILL BE BETWEEN 18C AND 19C TODAY...AND SOME SUN TODAY SHOULD
ALLOW HIGHS TO RISE TO BETWEEN 82F AND 86F.
&&
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 449 AM EDT THU AUG 21 2014
MAIN CONCERN THIS PERIOD IS POTENTIAL FOR EXCESSIVE HEAT AS STRONG
UPR LEVEL RIDGE BUILDS INTO THE AREA RESULTING IN HEAT INDEX
READINGS IN THE 90S EACH AFTN. ALTHOUGH THESE READINGS ARE A BIT
BLO OUR ADVISORY CRITERIA... IMPACTS MAY BE GREATER THAN USUAL DUE
TO EXPECTED RATHER LONG DURATION OF THE HEAT WAVE... AND
DIFFICULTY FOR PEOPLE TO BECOME ACCLIMATED TO THE HEAT GIVEN
ABNORMALLY COOL TEMPS THUS FAR THIS SUMMER.
CONVECTION AT NOSE OF A WK WLY LLJ MAY BE ONGOING IN OUR AREA AT
THE START OF THE PERIOD FRIDAY MORNING. WK LOW LEVEL WAA PATTERN
AND STNRY SFC BOUNDARY DRAPED ACROSS NERN PORTION OF THE CWA
EXPECTED FRI WHICH MAY PROVIDE FOCUS FOR REDEVELOPMENT IN THE AFTN
AS AIRMASS DESTABILIZES. THIS BOUNDARY EXPECTED TO REMAIN OVER THE
AREA FRI NGT WITH NOSE OF WSWLY LLJ OVER THE MID MS VALLEY
PROVIDING FORCING FOR CONVECTION UPSTREAM OVERNIGHT WHICH COULD BE
SUSTAINED INTO OUR AREA GIVEN LINGERING WK/MODERATE ELEVATED
INSTABILITY. RATHER STRONG NWLY UPR LEVEL FLOW ON EAST SIDE OF MS
VALLEY RIDGE WILL PROVIDE DECENT DEEP LAYER SHEAR FRI/FRI
NGT...ESPECIALLY OVER ERN PORTIONS OF THE CWA WHICH ALSO COULD AID
IN CONVECTIVE PERSISTENCE AS WELL AS SUPPORT A FEW STRONG/SVR
STORMS AROUND PEAK HEATING FRI AFTN/EVE. DOUBT CONVECTION WILL BE
SUFFICIENTLY WIDESPREAD OR LAST LONG ENOUGH TO HOLD TEMPS DOWN
SIGNIFICANTLY FRIDAY. GIVEN H85 TEMPS PROGGED IN THE 19-20C RANGE
STAYED CLOSE TO PREVIOUS FCST WITH HIGHS RANGING FROM THE M80S NE
TO AROUND 90 SW. DWPTS SHOULD ALSO BE RISING TO THE L-M70S WHICH
WILL RESULT IN AFTN HEAT INDICES ABOUT 5-10F HIGHER THAN TEMPS.
LIGHT WINDS FRI NGT SHOULD ALLOW FOR SOME RADIATIONAL COOLING SO
EXPECT MINS TO BE IN THE U60S NE AND L70S SW.
SIMILAR CONDITIONS EXPECTED SATURDAY. UPR RIDGE AXIS SHOULD MOVE
SLIGHTLY EAST INTO OUR AREA AS STRONG TROF MOVES ACROSS THE NRN
ROCKIES. E-W ORIENTED SURFACE BOUNDARY WILL LIKELY REMAIN OVER THE
AREA PROVIDING SOME FOCUS FOR CONVECTION AS AIRMASS DESTABILIZES
DURING THE DAY. WK LOW LEVEL GRADIENT WINDS AND VERY MOIST AIRMASS
OVER THE AREA SHOULD AGAIN LIMIT HEATING BUT EXPECT SUFFICIENT
MIXING TO ALLOW FOR HIGHS CLOSE TO FRIDAYS READINGS AS SUGGESTED BY
MAV MOS TEMPS.
STNRY SFC BOUNDARY SHOULD LIFT NORTH OF OUR CWA SAT NGT-SUNDAY AS
SFC LOW DEEPENS OVER THE NRN PLAINS. THIS SHOULD RESULT IN MAINLY
DRY CONDITIONS BY SUNDAY WITH TEMPS CONTG TO SLOWLY WARM. NRN PLAINS
LOW EXPECTED TO LIFT NE-E INTO ONTARIO MONDAY AND TO QUEBEC TUE WITH
TRAILING WK CDFNT DROPPING SOUTH INTO OUR AREA BY THAT TIME. SOME
SUPPRESSION OF UPR RIDGE PER ECMWF SOLUTION SEEMS APPROPRIATE AS
SHRTWV BREAKS OVER THE TOP ACROSS THE UPR GRTLKS... SO WKNG CAPPING
INVERSION/CHC TSTMS... AND SLIGHTLY LOWER TEMPS FCST BY TUE. MEDIUM
RANGE MODELS DIFFERING SOLUTIONS WRT PERSISTENCE OF UPR RIDGE TUE
LEADING TO EVEN GREATER DIFFERENCES BY WED WITH ECMWF SUGGESTING
RIDGING BUILDING BACK INTO OUR REGION AS CLOSED LOW DEVELOPS IN
THE WRN U.S., WHILE GFS FCSTG MORE PROGRESSIVE WRN TROF WITH A STRONG
SHRTWV APPROACHING THE MIDWEST BY WED EVE. GIVEN LARGE DIFFERENCES
STAYED CLOSE TO PREVIOUS FCST WHICH WAS FOR CONTD SLOW COOLING
TREND AND A LOW CHC OF TSTMS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 553 AM EDT THU AUG 21 2014
UPPER LEVEL JET DYNAMICS WERE HELPING TO TRIGGER STORMS IN AN AREA
FROM SOUTHERN WI INTO NW INDIANA. HAVE KEPT THE BULK OF THE
TIMING OF THE STORMS IN THE ONGOING TAFS...AND HAVE KEPT THUNDER
TONIGHT. THETA E FLUX WILL INCREASE TONIGHT...WITH MORE WIDESPREAD
ACTIVITY EXPECTED AS AN UPPER LEVEL SYSTEM DROPS SOUTHEAST INTO
THE AREA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
UPDATE...MARSILI
SYNOPSIS...SKIPPER
SHORT TERM...SKIPPER
LONG TERM...JT
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 DODGE CITY KS
606 AM CDT Thu Aug 21 2014
...Updated aviation discussion...
.SHORT TERM...(Today and tonight)
ISSUED AT 219 AM CDT THU AUG 21 2014
An upper level low will continue to slowly move eastward today
through tonight with a large upper level high centered over the
southeast United States. Mid levels of the atmosphere become more
saturated as today progresses with increased cloudiness expected
this evening into the overnight period. A trough of low pressure
will be observed at the surface, extending from northwest Kansas
back into southeast Colorado. Meanwhile, a dome of high pressure
will be located across the southeast United States. These features
will allow south to southwest winds to be felt today through tonight
with breezy conditions likely this afternoon as the atmosphere
mixes. During peak heating, a few thunderstorms may form ahead of
the aforementioned trough. Severe storms are not expected, but with
such a wide T/Td separation, a few storms may be capable of
producing strong winds up to 55 mph. Any storms that do form should
move eastward this evening then move out of or dissipate by or
around midnight. Highs today are forecasted to reach into the mid to
upper 90s with around 100 degrees across the KS/OK border. Lows
tonight are expected to range from the upper 60s across the KS/CO
border to the mid 70s across south central Kansas.
.LONG TERM...(Friday through Wednesday)
ISSUED AT 315 AM CDT THU AUG 21 2014
A southwesterly flow will persist across the Central Plains
through the weekend period into early next week as an upper ridge
axis remains nearly stationary from the lower Mississippi Valley
to the Western Great Lakes Region. All the models are in decent
agreement with an upper low, located just off the coast of
southern California at 00z Thursday, weakening as it approaches
the central Rockies late week and early this weekend. Cloud cover
and precipitation chances will improve as tropical moisture
increases ahead of this approaching upper level system so will
retain higher chances across west central and north central Kansas
Friday night given the timing of this weakening upper system and
location of a surface boundary. Precipitation chances will then
continue from late this weekend through early next week as another
upper level trough approaches the area from the west and a cold
front drops south into western Kansas.
Temperatures around 100 degree on Friday still looks on track
based on the 850mb to 700mb temperature trends from the ECMWF,
NAM, and GFS. Temperatures will be slightly cooler over the
weekend period given the increase in tropical moisture and
slightly cooler temperatures in the 850mb to 700mb level at 00z
Sunday and 00z Monday. Temperatures will fall back to more
seasonal levels early next week as the cold front moves south into
portions of western Kansas.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 604 AM CDT THU AUG 21 2014
06z NAM BUFR soundings along with 10z surface observations and
the latest HRRR indicating cloud bases early this morning and late
this afternoon will be at or above 5000ft AGL. A few widely
scattered showers across north central Kansas will taper off by
15z. Late day instability will result in another slight chance for
showers and thunderstorms along a surface boundary which will
extend across western Kansas, however at this time given how
widely scattered these storms will be late today have decided not
to include them in the 12z tafs. Gusty southwest winds at 15 to
near 20 knots today will subside back into the 10 to 15 knot range
by sunset.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 98 73 99 73 / 20 20 20 20
GCK 97 71 98 70 / 20 20 20 30
EHA 96 70 97 70 / 20 20 20 30
LBL 99 72 99 73 / 20 20 20 20
HYS 99 73 99 73 / 20 20 20 30
P28 99 76 100 77 / 10 10 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Hovorka_42
LONG TERM...Burgert
AVIATION...Burgert
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1050 AM EDT THU AUG 21 2014
.UPDATE...
ISSUED AT 1050 AM EDT THU AUG 21 2014
14Z SFC ANALYSIS SHOW GENERAL LOW PRESSURE NORTH OF THE OHIO RIVER
WITH HIGHER PRESSURE FOUND TO THE SOUTH. A STATIONARY BOUNDARY EXISTS
THROUGH THE NORTHERN PORTIONS OF THE OHIO VALLEY AND WESTERN PARTS OF
THIS FRONT...CONNECTED BACK TO DEEPER LOW PRESSURE OVER THE NORTHERN
PLAINS...HAS BEEN A GENESIS REGION FOR RECENT MCS ACTIVITY. THIS
ACTIVITY IS ALSO SUPPORTED BY A STREAM OF MID LEVEL ENERGY RIDING
ALONG THE NORTHERN FRINGE OF A DEVELOPING RIDGE TO THE SOUTHWEST OF
KENTUCKY. THIS WOULD TEND TO SUPPORT CONVECTION WORKING SOUTHEAST
FROM THE UPPER MIDWEST TO THE CENTRAL APPALACHIANS PASSING BY JUST TO
OUR NORTHEAST. HOWEVER...INSTABILITY BUILDING WITH THE RECENT
ARRIVAL OF SUMMER TIME HEAT AND HUMIDITY ACROSS KENTUCKY WILL BE
ENOUGH TO KEEP A THREAT OF THE STORMS AND THEIR OUTFLOW BOUNDARIES
SNEAKING INTO NORTHEAST PORTIONS OF THE CWA AND PERHAPS FURTHER TO
THE SOUTHWEST IN THE AFTERNOON. THE CURRENT RADAR HAS A HEALTHY
CLUSTER OF STORMS CROSSING FROM INDIANA INTO OHIO WITH A GROWING
SOUTHERN EXTENT TRACKING THROUGH NORTHERN KENTUCKY. EXPECT THIS TO
BRUSH INTO NORTHERN PARTS OF THE FORECAST AREA THROUGH THE NEXT
SEVERAL HOURS. THE HRRR KEEPS THIS FIRST WAVE JUST NORTH OF THE
CWA...WHILE THE 12Z NAM12 DIPS THE CONVECTION DEEPER INTO EAST
KENTUCKY. FOR THIS UPDATE HAVE SPLIT THE DIFFERENCE BETWEEN THESE TWO
SCENARIOS AND PEAKED POPS IN THE NORTHEAST THROUGH THE AFTERNOON WITH
SOME SMALL TO MODERATE POPS EVEN DOWN INTO THE CUMBERLAND VALLEY BY
EVENING. HIGH PWS AND THE RAINS OF THE PAST SEVERAL DAYS WILL MEAN A
THREAT OF FLASH FLOODING FOR PLACES THAT SEE REPEATED STORMS...
PARTICULARLY THROUGH THE MID SECTION OF THE CWA. SPC HAS PLACED
EASTERN PARTS OF THE AREA...ALONG THE PREVIOUSLY DISCUSSED STORM
TRACK...IN A SLIGHT RISK FOR SEVERE WEATHER...MAINLY DAMAGING WINDS
AND LARGE HAIL. THIS APPEARS REASONABLE GIVEN THE HIGH CAPE...LOW
LIS...AND LACK OF A MID LEVEL CAP. ACCORDINGLY THIS CONCERN WILL
CONTINUE TO BE HIGHLIGHTED IN THE HWO ALONG WITH A MENTION OF THE
HEAT AND HUMIDITY...TEMPS NEAR 90 AND DEWPOINTS IN THE 70S...THROUGH
THE WEEKEND. HAVE ALSO FINE TUNED THE T AND TD GRIDS PER THE LATEST
OBS...TRENDS...AND CONSSHORT GUIDANCE. THESE UPDATES HAVE BEEN SENT
TO THE NDFD AND WEB SERVERS WITH NEW HWO AND ZONES ON THEIR WAY.
UPDATE ISSUED AT 757 AM EDT THU AUG 21 2014
THE FORECAST REMAINS ON TRACK THIS MORNING. FRESHENED UP THE HOURLY
TEMPERATURES...DEW POINTS...AND SKY COVER TO ACCOUNT FOR THE LATEST
TRENDS IN THE OBSERVATIONS.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 357 AM EDT THU AUG 21 2014
THE LATEST SURFACE MAP FEATURES HIGH PRESSURE ACROSS THE GULF COAST
STATES...WITH LOW PRESSURE ACROSS THE PLAINS STATES. A STATIONARY
BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE GREAT LAKES/OHIO
VALLEY REGION. ALOFT...AN UPPER LEVEL LOW CONTINUES TO SPIN ACROSS
THE NORTHERN GREAT LAKES...WITH AN UPPER LEVEL RIDGE CENTERED NEAR
THE NORTHERN GULF OF MEXICO...AND MORE TROUGHING FEATURED ACROSS
THE NORTHERN ROCKIES. SEVERAL COMPLEXES OF THUNDERSTORMS HAVE BEEN
GENERATING AND THEN RIDING SOUTHEAST ON THE PERIPHERY OF THE UPPER
LEVEL RIDGE OVER THE PAST FEW DAYS.
CURRENTLY...EASTERN KENTUCKY REMAINS QUIET AS ONLY A WEAKENING
SMALLER COMPLEX OF THUNDERSTORMS IS SLOWLY MOVING THROUGH SOUTHEAST
ILLINOIS AND SOUTHWEST INDIANA. THE NEXT MORE ORGANIZED COMPLEX IS
CURRENTLY MOVING THROUGH MINNESOTA.
THE MODEL GUIDANCE HAS BEEN ALL OVER THE PLACE WITH THE TIMING OF THE
MORE ORGANIZED CONVECTION AS OF LATE. AS SUCH...HAVE USED A GENERAL
BLEND OF THE GUIDANCE AND THE INHERITED FORECAST. AS THE UPPER LEVEL
RIDGE SLOWLY BUILDS INTO THE REGION THROUGH FRIDAY...IT WILL
GENERALLY NUDGE THE MCS TRACK FURTHER NORTHEAST...HOWEVER SINCE THERE
WILL BE PLENTY OF FUEL FOR THE STORMS AND A WEAK SYNOPTIC PATTERN IN
PLACE...CAN NOT RULE OUT OUTFLOW INFLUENCE FURTHER SOUTHWEST. SOME
STORMS COULD APPROACH SEVERE LIMITS...AND ISOLATED FLASH FLOODING
WILL ALSO BE A POSSIBILITY...ESPECIALLY WHERE STORMS CAN MOVE
PARALLEL TO ANY ESTABLISHED OUTFLOW BOUNDARIES. WILL HIGHLIGHT THESE
THREATS IN THE HWO. POPS WILL GENERALLY PEAK IN THE AFTERNOON HOURS
TODAY AND FRIDAY...WITH LESSER CHANCES DURING THE OVERNIGHT HOURS.
HIGHS TODAY WILL AVERAGE IN THE 85 TO 90 DEGREE RANGE...WITH AROUND
90 DEGREES EXPECTED FOR MOST LOCATIONS ON FRIDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 357 AM EDT THU AUG 21 2014
THE EXTENDED PORTION OF THE FORECAST BEGINS ON FRIDAY NIGHT WITH A
WELL DEVELOPED MID LEVEL RIDGE CENTERED OVER THE MID WEST AND
LONGWAVE TROUGH ENTERING THE NORTHWEST WITH AN EXITING TROUGH OVER
THE NORTHEAST. THE MID LEVEL RIDGE AXIS EVENTUALLY SHIFTS EAST OVER
THE OH VALLEY BY MONDAY AS IT WEAKENS A BIT WITH THE APPROACHING
TROUGH OVER THE NORTHERN PLAINS AND THE TROUGH OVER THE NORTHEAST
EXITING INTO THE ATLANTIC. THIS PATTERN BASICALLY KEEPS THE RIDGE
OVER EASTERN KENTUCKY THROUGH THE REST OF THE EXTENDED.
WITH THIS PATTERN IN PLACE THROUGH SUNDAY...EASTERN KENTUCKY REMAINS
IN NORTHWEST FLOW WITH STILL A FEW MCS/S LIKELY POISED TO TRACK
SOUTHEAST INTO THE AREA FOR THIS WEEKEND. WHILE MODELS INHERENTLY
WILL HAVE TROUBLE TRACKING THEM...THE FIRST ONE SHOULD BE MOVING
THROUGH FRIDAY NIGHT WITH THE NEXT ONE POSSIBLY SATURDAY NIGHT. BY
SUNDAY...THE RIDGE AXIS REALLY BEGINS TO SET IN AND ADDITIONAL
STRONG CONVECTION MAY BE LESS LIKELY AND MAY BE MORE TIED TO DIURNAL
PROCESSES WITH A STATIONARY BOUNDARY ALONG THE EASTERN PORTION OF THE
CWA. BY MONDAY AND THROUGH WEDNESDAY...THE MID LEVEL RIDGE AXIS
MOVES OVER THE AREA WHICH SHOULD EFFECTIVELY CUT OFF CONVECTION...AT
LEAST DEEP CONVECTION. SOME AFTERNOON SHOWERS AND POSSIBLY A STORM OR
TWO MAY DEVELOP UNDER THE RIDGE. THE SOLUTION OF THE ALL MODEL BLEND
WOULD SUGGEST SOME UNCERTAINTY THERE WITH THE BEST CHANCE OF PRECIP
FRIDAY NIGHT THROUGH SUNDAY. THIS IS IN GOOD AGREEMENT WITH THE GFS
AND EURO AS WELL. OVERALL THE BROAD BRUSH OF POPS THROUGH THE FIRST 3
DAYS OF THE EXTENDED SEEMS NEEDED DUE TO THE NATURE OF THE MODELS
HAVING TROUBLE DEPICTING THE COMPLEXES MOVING THROUGH BUT DID GO WITH
SOME DIURNAL CHARACTERISTICS.
BY THE END OF THE EXTENDED...THE MODELS SEEM TO HINT AT THE RIDGE
MOVING FARTHER EAST AS A STRONG SHORTWAVE AND ASSOCIATED COLD FRONT
SEEMS POISED TO MOVE THROUGH THE MS RIVER VALLEY AND INTO THE OH
VALLEY. IN ADDITION...THE WARM AND MUGGY WEATHER STILL LOOKS TO BE
ON TAP THROUGH THE WEEKEND WITH HIGHS AROUND 90 THROUGH MONDAY AND
DEW POINTS AROUND 70. THE END OF THE EXTENDED DOES SHOW SOME RELIEF
FROM THE WARM AND HUMID WEATHER WITH THE APPROACH OF THE
AFOREMENTIONED COLD FRONT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 757 AM EDT THU AUG 21 2014
IFR OR WORSE FOG/STRATUS WILL DISSIPATE BY AROUND 13Z. SCATTERED TO
NUMEROUS CONVECTION WILL LIKELY THREATEN ONCE AGAIN FROM 16Z THROUGH
EARLY THIS EVENING. TIMING THIS ACTIVITY CONTINUES TO BE VERY
CHALLENGING SO WILL KEEP VCTS WORDING ONLY AT THIS TIME. SOME MVFR
OR WORSE FOG WILL LIKELY BE SEEN ONCE AGAIN AFTER 04Z TONIGHT. WINDS
OF AROUND 5 KTS OR LESS WILL REMAIN OUT OF THE SOUTHWEST THROUGH THE
PERIOD AS WELL.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS PADUCAH KY
639 AM CDT Thu Aug 21 2014
.UPDATE...
Issued at 517 AM CDT THU AUG 21 2014
Minor adjustment to account for light showers over Southern
Illinois and departing convection over Southwest Indiana before
daybreak. The 13km RUC and 3km HRRR suggest a subtle channeled
vortiicity intersecting very minor, low amplitude shortwave
centered around the 14-17kft layer on the KVWX VAD wind profile
between 9-10z. Precipitation chances will remain marginal and
suspect subsidence in this layer will serve to speed up clearing
of cloud debris by mid-morning. With this in mind, went slightly
higher with temperatures through early afternoon.
Should clouds linger 1-3 hours longer than expected, may have to
dial back temperatures and heat indexes to the main forecast
package levels for this afternoon.
&&
.SHORT TERM...(Today through Saturday)
Issued at 306 AM CDT THU AUG 21 2014
Strong thunderstorm clusters rolled through northern parts of the
CWA early this morning, producing some very heavy rain and gusty
winds. They were associated a small upper level disturbance that
is moving across parts of southern IL/southwest IN. The only short
term model that seems to have a good handle on this complex is the
HRRR, which continues to take these remnants east/southeast and
out of the EVV Tri State region over the next few hours. There are
a few light showers forming further west in southeast MO which may
be forming due to decent instability and maybe a weak boundary
over that area per the latest LAPS data. Will opt for some
isolated coverage through about 13Z to cover any remaining
activity as this disturbance moves out of the region.
We will see upper heights build today and we should see the mid
level clouds clear during the morning hours, leaving the afternoon
to heat up. Unlike yesterday, when clouds hung out long enough to mess
with temperatures in our northern areas, it appears we should have
enough sunshine today that all locations should reach the low/mid
90s, as 850mb temperatures do not really change too much. The only
issue may be our eastern counties. If clouds to not clear until late
there, the heat advisory may be in jeopardy. Will keep it going
area wide for now due to uncertainties in cloud cover.
The ring of fire pattern will be rather active to our north, as
disturbance rotate around the upper high. Believe that most of the
activity should stay well to our north today, tonight and into
Friday, but the far northern/northeastern counties might need to be
watched just in case outflow boundaries from storms to the north
light up further south than anticipated.
Friday into Saturday, the upper high over the region becomes even
more amplified, as a upper level trough crashes into the Pacific
northwest. The atmosphere really dries out in the low levels and
even aloft as this occurs. This should really shut off any chances
for potential convection. The heat begins to build even more for
Friday and Saturday as low level temps rise a few more degrees,
which should put us into the mid or upper 90s through Saturday.
Night time lows will remain in the mid 70s. This heat, coupled with
high humidity values, should continue to warrant our ongoing heat
advisory, which might even have to be extended.
.LONG TERM...(Saturday night through Wednesday)
Issued at 306 AM CDT THU AUG 21 2014
The main concern during the long term period will be the extended
duration of potentially hazardous heat. A deep layer subtropical
high will be anchored over the Lower Ohio and Mid Mississippi
Valleys late in the weekend into early next week.
As far as the daily details...
Sunday into Monday...the center of the high /850 to 500 mb/ is
forecast to be nearly overhead. The models forecast some
strengthening of the high...with 500 mb heights near 594 dm by
Monday. Heat indices will likely continue to meet or exceed advisory
thresholds...requiring an eventual extension of headlines.
Tuesday into Wednesday...very little change is indicated regarding
the location of the upper ridge. However...the low level anticyclone
is forecast to shift eastward. Due to weaker capping and less
subsidence...there should be a little more cloudiness and isolated
diurnal convection. This moisture may hold daytime highs down a bit.
&&
.AVIATION...
Issued at 638 AM CDT THU AUG 21 2014
With this issuance attempted to account for lift associated with
minor shortwave moving through the TAF sites before 17z. Added a
brief MVFR ceiling for KEVV and KOWB through 17z, otherwise kept
ceilings near 110 kft AGL as the dominate cloud cover prior to 17.
The ridge should build in quickly this afternoon, diminishing
opaque cloud cover below 12kft agl. There may be some cirrus in
the area, but did not account for it at this time. Minor visbility
restriction was added after 06z Friday for all of the TAF sites,
ranging between 5 and 6 statute miles.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY until 7 PM CDT Saturday FOR ILZ075>078-080>094.
MO...HEAT ADVISORY until 7 PM CDT Saturday FOR MOZ076-086-087-100-
107>112-114.
IN...HEAT ADVISORY until 7 PM CDT Saturday FOR INZ081-082-085>088.
KY...HEAT ADVISORY until 7 PM CDT Saturday FOR KYZ001>022.
&&
$$
UPDATE...Smith
AVIATION...Smith
AREA FORECAST DISCUSSION
NWS PADUCAH KY
518 AM CDT Thu Aug 21 2014
.UPDATE...
Issued at 517 AM CDT THU AUG 21 2014
Minor adjustment to account for light showers over Southern
Illinois and departing convection over Southwest Indiana before
daybreak. The 13km RUC and 3km HRRR suggest a subtle channeled
vortiicity intersecting very minor, low amplitude shortwave
centered around the 14-17kft layer on the KVWX VAD wind profile
between 9-10z. Precipitation chances will remain marginal and
suspect subsidence in this layer will serve to speed up clearing
of cloud debris by mid-morning. With this in mind, went slightly
higher with temperatures through early afternoon.
Should clouds linger 1-3 hours longer than expected, may have to
dial back temperatures and heat indexes to the main forecast
package levels for this afternoon.
&&
.SHORT TERM...(Today through Saturday)
Issued at 306 AM CDT THU AUG 21 2014
Strong thunderstorm clusters rolled through northern parts of the
CWA early this morning, producing some very heavy rain and gusty
winds. They were associated a small upper level disturbance that
is moving across parts of southern IL/southwest IN. The only short
term model that seems to have a good handle on this complex is the
HRRR, which continues to take these remnants east/southeast and
out of the EVV Tri State region over the next few hours. There are
a few light showers forming further west in southeast MO which may
be forming due to decent instability and maybe a weak boundary
over that area per the latest LAPS data. Will opt for some
isolated coverage through about 13Z to cover any remaining
activity as this disturbance moves out of the region.
We will see upper heights build today and we should see the mid
level clouds clear during the morning hours, leaving the afternoon
to heat up. Unlike yesterday, when clouds hung out long enough to mess
with temperatures in our northern areas, it appears we should have
enough sunshine today that all locations should reach the low/mid
90s, as 850mb temperatures do not really change too much. The only
issue may be our eastern counties. If clouds to not clear until late
there, the heat advisory may be in jeopardy. Will keep it going
area wide for now due to uncertainties in cloud cover.
The ring of fire pattern will be rather active to our north, as
disturbance rotate around the upper high. Believe that most of the
activity should stay well to our north today, tonight and into
Friday, but the far northern/northeastern counties might need to be
watched just in case outflow boundaries from storms to the north
light up further south than anticipated.
Friday into Saturday, the upper high over the region becomes even
more amplified, as a upper level trough crashes into the Pacific
northwest. The atmosphere really dries out in the low levels and
even aloft as this occurs. This should really shut off any chances
for potential convection. The heat begins to build even more for
Friday and Saturday as low level temps rise a few more degrees,
which should put us into the mid or upper 90s through Saturday.
Night time lows will remain in the mid 70s. This heat, coupled with
high humidity values, should continue to warrant our ongoing heat
advisory, which might even have to be extended.
.LONG TERM...(Saturday night through Wednesday)
Issued at 306 AM CDT THU AUG 21 2014
The main concern during the long term period will be the extended
duration of potentially hazardous heat. A deep layer subtropical
high will be anchored over the Lower Ohio and Mid Mississippi
Valleys late in the weekend into early next week.
As far as the daily details...
Sunday into Monday...the center of the high /850 to 500 mb/ is
forecast to be nearly overhead. The models forecast some
strengthening of the high...with 500 mb heights near 594 dm by
Monday. Heat indices will likely continue to meet or exceed advisory
thresholds...requiring an eventual extension of headlines.
Tuesday into Wednesday...very little change is indicated regarding
the location of the upper ridge. However...the low level anticyclone
is forecast to shift eastward. Due to weaker capping and less
subsidence...there should be a little more cloudiness and isolated
diurnal convection. This moisture may hold daytime highs down a bit.
&&
.AVIATION...
Issued at 306 AM CDT THU AUG 21 2014
Other than some lingering rain/thunder storms over the KEVV which
will exit the area within the next hour, all is quiet over the
other terminals. Some morning fog may develop though early this
morning, although extensive cloud cover may preclude vsbys from
going down too far. Mid level clouds should slowly move out of the
area this morning and some cu may form by afternoon. Light
southwest winds are expected.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY until 7 PM CDT Saturday FOR ILZ075>078-080>094.
MO...HEAT ADVISORY until 7 PM CDT Saturday FOR MOZ076-086-087-100-
107>112-114.
IN...HEAT ADVISORY until 7 PM CDT Saturday FOR INZ081-082-085>088.
KY...HEAT ADVISORY until 7 PM CDT Saturday FOR KYZ001>022.
&&
$$
UPDATE...Smith
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1035 AM CDT THU AUG 21 2014
.DISCUSSION...
LATEST VIS SATELLITE IMAGERY SHOWING EXPANSIVE STRATOCUMULUS DECK
ENCOMPASSING MOST OF THE FOUR STATE REGION THIS MORNING. CUMULUS
IS TAKING ON MORE OF A HORIZONTAL ROW APPEARANCE WHICH IS
INDICATIVE OF SOME MIXING BEGINNING TO TAKE PLACE IN THE LOWER
ATMOSPHERE AS HEATING TAKES PLACE. AS A RESULT...EXPECT SOME PEEKS
OF SUN TO BEGIN OVER THE NEXT COUPLE HOURS WITH EVENTUALLY SKIES
BECOMING PARTLY CLOUDY ACROSS THE REGION.
STRONG WINDS IN THE LOWEST 5KFT ALLOWED THE STRATUS TO MOVE
QUICKLY NORTHWARD AND CONDENSE EARLY THIS MORNING AND WE ARE
STARTING TO SEE SOME OF THIS MIX DOWN ACROSS NE TX THIS MORNING
WITH STRONGER WIND GUSTS NOTED NORTH AND WEST OF THE I-30 CORRIDOR
ACROSS TX.
LOOKING AT NEW RAW 12Z NAM OUTPUT...THERE REMAINS A WEAK SHEAR
AXIS ACROSS OUR EASTERN MOST ZONES EARLY THIS MORNING. WEAK BUT
OBVIOUS 850-700MB THETAE AXIS ALSO RESIDES ACROSS THIS GENERAL
AREA AND AS A RESULT...THIS WILL MOST LIKELY BE THE FAVORABLE
REGION TO SEE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS LATER
TODAY.
OTHERWISE...ONCE THE CLOUDS THIN...SHOULD HAVE NO PROBLEMS GETTING
TEMPERATURES TO REACH FCST MAX TEMPS WITH 15Z OBSERVATIONS ALREADY
RUNNING SOME 1 TO 3 DEGREES ABOVE THOSE EXPERIENCED ON WEDNESDAY
ATTM.
NO UPDATE NECESSARY TO THE FORECAST THIS MORNING.
13
&&
.PREV DISCUSSION... /ISSUED 435 AM CDT THU AUG 21 2014/
DISCUSSION...
11-3.9U SATELLITE IMAGERY THIS MORNING INDICATES A VORTICITY MAXIMUM
OVER NCNTRL LA...WHICH IS ALONG A ELEVATED WEAK SHEAR AXIS NOTED ON
THE WATER VAPOR LOOP EXTENDING FROM SE TX ACROSS NCNTRL LA INTO CNTRL
MS/NRN AL. THIS FEATURE HAS MAINTAINED AN EXTENSIVE AC CANOPY THIS
MORNING OVER MUCH OF NCNTRL LA...WHICH ARE THE CONVECTIVE REMNANTS OF
THE ISOLATED SEABREEZE CONVECTION THAT AFFECTED THESE AREAS WEDNESDAY
AFTERNOON AND EVENING. A WEAK UPPER LOW NOTED ON THE WATER VAPOR LOOP
NOW AFFECTING THE ERN MX COAST S OF BRO HAS ALREADY RESULTED IN
ENHANCED ONSHORE FLOW WHICH HAS LED TO INCREASED MOISTURE CONVERGENCE
ALONG A W TO E SFC TROUGH WHICH LIES NEAR THE I-10 CORRIDOR. THIS HAS
RESULTED IN ISOLATED CONVECTION DEVELOPING/STREAMING N ACROSS SW
LA...BUT HAVE WEAKENED WHERE SFC CONVERGENCE IS LOST FARTHER N OF THE
SFC TROUGH. THE PROGS DO WEAKEN THE VORT MAX LATER TODAY AS THE CENTER
OF THE 500MB RIDGE BEGINS TO BUILD NNW INTO THE LOWER MS VALLEY...BUT
SHOULD STILL SEE ANOTHER DAY WHERE SEABREEZE CONVECTION WILL AFFECT
THE SRN ZONES MAINLY DURING THE AFTERNOON/EARLY EVENING. GIVEN THE SSW
850-700MB FLOW...THE SEABREEZE SHOULD NOT PUSH AS FAR N ACROSS E TX/NW
LA AS IT HAS IN RECENT DAYS...BUT THE HRRR AND GFS SUGGEST THAT THE
CONVECTION COULD PUSH FARTHER NNE ACROSS THE ERN SECTIONS OF NCNTRL
LA. FOR THAT REASON...HAVE EXTENDED SLIGHT CHANCE POPS FARTHER N INTO
LINCOLN/UNION/OUACHITA PARISHES THIS AFTERNOON/EVENING...BUT A
STABILIZING BNDRY LYR FROM THE LOSS OF HEATING RESULTS IN THE QUICK
DISSIPATION OF THE CONVECTION. DID ALSO INCLUDE LOW CHANCE POPS FOR
THE SE SECTIONS OF NCNTRL LA...WHERE EXTRAPOLATION OF THE CURRENT
CONVECTION WILL LIKELY RESULT IN ADDITIONAL OUTFLOW BNDRYS THAT WILL
FOCUS MORE SCT DEVELOPMENT ESPECIALLY WHEN PEAK HEATING IS REACHED.
WITH THE AC SHIELD GRADUALLY THINNING BY AFTERNOON...AND THE MORNING
LOW STRATUS QUICKLY LIFTING THIS MORNING...MAX TEMPS TODAY SHOULD BE
NEAR IF NOT SLIGHTLY WARMER THAN WHAT WAS OBSERVED WEDNESDAY.
THE HEAT IS ON FRIDAY THROUGH EARLY NEXT WEEK AS THE CENTER OF THE
UPPER RIDGE RESIDES IN VC OF OUR REGION OVER LOWER MS VALLEY. THIS
SHOULD RESULT IN MAX TEMPS CLIMBING INTO THE UPPER 90S AREAWIDE BY THE
WEEKEND...WITH A FEW TRIPLE DIGIT TEMPS NOT OUT OF THE QUESTION OVER
PORTIONS OF THE REGION. EVEN WITH THE 700MB RIDGE CENTERED OVER ERN AR
SUNDAY...AMPLE SOIL MOISTURE OVER ERN LA/SE AR SHOULD HELP MAINTAIN
TEMPS BELOW THE CENTURY MARK...BUT RESULT IN HIGHER DEWPOINTS/HEAT
INDICES SUCH THAT A HEAT ADVISORY MAY BE NEEDED FOR PORTIONS OF NCNTRL
LA/S AR THIS WEEKEND. HAVE TRENDED SLIGHTLY COOLER THAN MAVMOS THIS
WEEKEND...ESPECIALLY GIVEN ITS WARM BIAS FOR THE LAST SEVERAL WEEKS.
THE PROGS CONTINUE TO SHIFT THE UPPER RIDGE CENTER FARTHER NE INTO THE
MID MS VALLEY BY MONDAY WITH THE RIDGE AMPLIFYING INTO THE GREAT LAKES
REGION...WITH THE EXTREME HEAT BEGINNING TO WEAKEN ITS GRIP ON OUR
AREA. BUT THIS WILL BE GRADUAL...UNTIL WEAKNESSES BENEATH THE RIDGE
CENTER ARE ABLE TO MIGRATE W ACROSS MS/SE LA MONDAY...WHICH MAY TOUCH
OFF ISOLATED CONVECTION OVER MUCH OF NCNTRL LA/DEEP E TX. WITH THESE
WEAKNESSES NUDGING CLOSER TO OUR REGION BY TUESDAY...MORE IN THE WAY
OF SCT CONVECTION IS EXPECTED OVER NCNTRL LA/DEEP E TX...WITH ISOLATED
CONVECTION POSSIBLE FARTHER W. FORECAST CONFIDENCE DIMINISHES
THEREAFTER...WITH THE GFS SUGGESTING AN UPPER TROUGH QUICKLY SHIFTING
E ACROSS THE PLAINS WEDNESDAY AND ACROSS THE SRN PLAINS/LOWER MS
VALLEY THURSDAY. MEANWHILE...THE ECMWF REMAINS STOUT WITH THE RIDGE
CENTER ACTUALLY RETROGRADING W BACK ACROSS THE CNTRL CONUS...WITH A
MUCH SLOWER AND WEAKER TROUGH PASSAGE /IF ANY AT ALL/ BY NEXT WEEKEND.
FOR NOW...HAVE MAINTAINED SLIGHT CHANCE POPS THROUGHOUT THE REMAINDER
OF THE EXTENDED...WHILE KEEPING NEAR NORMAL TEMPS THROUGH THE PERIOD.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 96 74 97 74 98 / 10 10 0 0 0
MLU 94 73 96 73 97 / 20 20 0 0 0
DEQ 94 72 95 72 96 / 0 0 0 0 0
TXK 95 74 96 74 97 / 0 0 0 0 0
ELD 94 72 96 73 97 / 10 10 0 0 0
TYR 97 75 97 75 97 / 10 10 0 0 0
GGG 95 74 96 74 97 / 10 10 0 0 0
LFK 96 74 97 74 97 / 20 10 0 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
13
AREA FORECAST DISCUSSION...UPDATE
NWS JACKSON MS
1030 AM CDT THU AUG 21 2014
.UPDATE...ROSE POPS SLIGHTLY THROUGH THE REST OF THE DAY IN MAINLY
THE WESTERN HALF OF ZONES. IN SOME OF THOSE WESTERN ZONES ALSO
LOWERED HIGH TEMPERATURE EXPECTATIONS A TOUCH. /BB/
&&
.DISCUSSION...VISIBLE SATELLITE ANALYSIS REVEALS A MESOSCALE
CONVECTIVE VORT (MCV) LEFTOVER FROM YESTERDAYS CONVECTION CURRENTLY
SPINNING OVER NE LA...EMBEDDED JUST TO THE WEST OF THE UPPER LEVEL
HIGH CENTER AFFECTING THE LOWER MS VALLEY REGION. DESPITE THE
PREVAILING RIDGE INFLUENCE...ISOLATED TO LOCALLY SCATTERED MIDDAY
THROUGH AFTERNOON SHOWERS AND THUNDERSTORMS LOOK TO BE POSSIBLE
ACROSS MAINLY THE WESTERN HALF OF ZONES OWING TO THE PRESENCE OF
SAID MCV. LATEST HRRR PAINTS THIS PICTURE QUITE WELL ALTHOUGH IT IS
POSSIBLE THOSE SOLUTIONS ARE A LITTLE OVERDONE. EXPECTING
CLOUDS/PCPN TO KEEP TEMPS DOWN A LITTLE IN WESTERN ZONES SO MAX
READINGS DROPPED THERE A DEGREE OR TWO. MORNING WET MICROBURST
CHECKLIST SUGGESTED MODERATE POTENTIAL FOR LOCALLY SEVERE DOWNBURSTS
GIVEN TEMPERATURES IN THE MID 90S SO CONVECTION WILL BE MONITORED
CLOSELY FROM THAT STANDPOINT...ALTHOUGH POTENTIAL STILL NOT DEEMED
HIGH ENOUGH TO INCLUDE MENTION IN THE HWO. /BB/
&&
.PREV DISCUSSION... /ISSUED 400 AM CDT THU AUG 21 2014/
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...A LITTLE WARMER EACH DAY
WITH AFTERNOON HEAT INDEX VALUES REMAINING THE MAIN CONCERN. EARLY
MORNING SURFACE ANALYSIS HAD A 1019MB RIDGE CENTERED OVER THE GULF
COAST. EARLY MORNING WATER VAPOR IMAGERY/RUC ANALYSIS SHOWED THE
CIRCULATION AROUND A 592DAM HIGH CENTERED OVER OUR AREA. THIS MID
LEVEL HIGH WILL STRENGTHEN FURTHER TODAY AND REMAIN CENTERED OVER
OUR CWA THROUGH FRIDAY NIGHT. TOGETHER RIDGING SURFACE AND ALOFT
OVER OUR REGION WILL ALLOW FOR A SLOW WARMING TREND INTO THE
WEEKEND. A RATHER MOIST AIRMASS WILL REMAIN OVER OUR AREA WITH PWS
OF AN INCH AND THREE QUARTERS TO TWO INCHES. THIS WILL HELP MAINTAIN
UPPER 60 TO LOWER 70 DEGREE DEW POINTS DURING THE HOTTEST PART OF
THE DAY. THE COMBINATION OF TEMPERATURES IN THE MID TO UPPER 90S
WITH THE HIGH RELATIVE HUMIDITY WILL RESULT IN MAXIMUM HEAT INDEX
VALUES OF 101-104F TODAY AND 102-106 FRIDAY. GFSMOS GUIDANCE WAS
AGAIN A LITTLE TOO WARM AND LEANED TOWARD A BLEND OF THE NAM AND
ECMWF MOS GUIDANCE FOR AFTERNOON HIGHS EACH DAY. MODEL CONSENSUS
STILL HINTS AT LATE AFTERNOON SEA BREEZE CONVECTION TRYING TO DRIFT
UP INTO OUR SOUTHERN ZONES. HAVE CARRIED ISOLATED WORDING IN THE
SOUTHWEST TODAY AND ONLY IN OUR SOUTHEAST MOST ZONES FRIDAY
AFTERNOON. RAIN CHANCES WILL REMAIN VERY LOW ELSEWHERE THROUGH THE
PERIOD. /22/
LONG TERM...SATURDAY THROUGH WEDNESDAY...THROUGH THE WEEKEND HEAT
AND HUMIDITY WILL BE BE THE PRIMARY ISSUE AS MEAN RIDGING CONTINUES
THROUGH SUNDAY...WHICH WILL BRING CLASSIC AUGUST SUMMER MUGGY
CONDITIONS. 850MB TEMPS WILL BE IN THE UPPER 20S TO AROUND 30C. THIS
WILL BRING TEMPS IN THE MID TO UPPER 90S THROUGH THE WEEKEND. WITH
LOWS IN THE 70S HEAT INDICES WILL BE A CONCERN. HEAT INDICES WILL BE
AROUND 100 TO 107 ON SATURDAY AND SUNDAY. WITH STRONG SUBSIDENCE
RAIN CHANCES WILL BE RATHER SCARCE THROUGH SUNDAY. AS WE GO INTO
NEXT WEEK MOISTURE WILL BUILD ACROSS THE REGION FROM THE EAST. THIS
WILL GIVE THE REGION A BREAK IN WARM AFTERNOON HIGH TEMPERATURES.
THUS 850MB TEMPS WILL COOL SOME INTO THE MIDDLE 20SC. RAIN CHANCES
WILL PICK UP AS DEEP TROPICAL MOISTURE BUILDS ACROSS THE REGION.
PWATS WILL INCREASE TO AROUND 2.2 INCHES. THERE WILL BE DECENT
INSTABILITY FOR SOME CONVECTIVE CHANCES FROM MONDAY THROUGH
WEDNESDAY WITH SOME LOCALLY HEAVY RAINFALL POTENTIAL. THE MEAN
RIDGING WILL FLUCTUATE SOME DURING THE UPCOMING WORK WEEK.
AS FAR AS THE TROPICS ARE CONCERN MODELS ARE KEEPING TROPICAL
SYSTEMS AWAY FROM THE GULF OF MEXICO AND PUSHING POSSIBLE TROPICAL
SYSTEMS OFF THE EAST COAST.
AS FAR AS MODEL DIFFERENCES ARE CONCERN MOST OF THE ENSEMBLES...
EURO...NAVY AND UK MODELS KEEP THE MEAN RIDGE DOMINANT OVER OUR
REGION. THE GFS TRIED TO BRING AN UPPER TROUGH OVER THE CENTRAL
PLAINS AND EVENTUALLY PUSHED A FRONT TOWARD THE REGION FOR THE LATER
PART OF THE WORK WEEK...WHICH SEEMS TO BE AN OUTLIER. MODELS WERE IN
GENERAL AGREEMENT WITH THE WEEKEND HEAT AND INCREASE IN TROPICAL
MOISTURE FROM THE EAST FOR NEXT WEEK.
AS FAR AS POPS AND TEMPS ARE CONCERN WENT CLOSE TO MEX AND GMOS
GUIDANCE FOR THE PERIOD./17/
&&
.AVIATION...VFR CONDS CURRENTLY PREVAIL AT ALL TAF SITES AND WILL
CONTINUE AT MOST INTO THE EVENING. ISOLATED SHOWERS/STORMS ARE PSBL
AT MAINLY IN W TO SW MS...WHICH COULD BRING DOWN KGLH/KJAN TO
MVFR/IFR CEILINGS BRIEFLY AROUND 20-23Z. WINDS WILL BE LIGHT MAINLY
FROM THE W TO SW AROUND 4-8KTS THIS AFTERNOON. /DC/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 96 73 97 73 / 14 6 7 5
MERIDIAN 96 72 97 73 / 8 6 9 5
VICKSBURG 94 73 97 72 / 26 6 5 4
HATTIESBURG 97 73 98 74 / 14 12 20 9
NATCHEZ 92 74 95 73 / 33 11 13 10
GREENVILLE 95 74 97 74 / 11 5 5 4
GREENWOOD 96 73 97 73 / 8 5 5 4
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
BB/DC/22/17
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1053 AM EDT THU AUG 21 2014
.SYNOPSIS...
THE POTENT UPPR LEVEL STORM SYSTEM CONTINUES TO SIT OVER THE
REGION. THIS SYSTEM WILL SUPPORT THE CHANCE FOR ADDITIONAL
SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT OVER NEW YORK AND
PENNSYLVANIA. THE UNSETTLED WEATHER PATTERN WILL SLOWLY IMPROVE BY
SATURDAY AS HIGH PRESSURE RETURNS TO THE REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
1050 AM UPDATE...
H5 LOW IS SPINNING OVR GEORGIAN BAY AT THIS TIME. S/WV IS MVG THRU
WRN NY AND HAS SPARKED OFF COMPLEX OF TSTMS ACRS THE FINGER LKS
AND NOW MVG INTO THE MOHAWK VLY. THESE STORMS HV DVLPD IN 500
MLCAPE AREA AND ARE MVG THUS ONLY GETTING 0.75-1 INCH PER HR AMNTS
OUT OF THE HEAVIEST CELLS.
EXPECT THIS WL LIKELY BE THE CASE THRU THE DAY AS STORMS DVLP THIS
AFTN. THE BULK OF CNY AND ALL OF NEPA ARE NOW IN SEE TEXT FOR SVR
STORMS THIS AFTN. 0-6KM BULK SHEAR VALUES INCRS ACRS ZONES FM THE
SRN TIER AND POINTS SOUTH TO BTWN 25-30KTS. WITH SOME BREAKS IN
CLDS ACRS FINGER LKS AS OF 14Z, INSTABILITIES WL BE ON THE INCRS
THIS AFTN. SFC LOW IS SITTING UP ACRS SRN ONTARIO WITH AN ILL-
DEFINED WMFNT EXTENDING SOUTH THRU CNTRL NY. LATEST HRRR IS NOW
SUGGESTING AREA OF STORMS MVG ACRS NRN ZONES WL BE PULLING INTO
ERN ZONES AND OUT OF CWA BY 20Z AS S/WV MVS OFF TO THE EAST.
HWVR, ATMOS WL RMN UNSTABLE THRU MOST OF THE DAY TDA AND WITH ANY
BNDRYS LURKING WL LKLY SEE DVLPMNT, THO NOT ENUF TO WARRANT LKLY
POPS AND WL REDUCE POPS DOWN TO HICHC AT BEST. NO OTHER CHGS
NEEDED TO GRIDS. WL CONTINUE THE MENTION OF LOCALLY HVY RAINFALL
IN HWO WITH PW VALUES 1-2 SD ABV NORMAL.
PREV DISCO BLO...
650 AM EDT UPDATE...
MOSTLY CLOUDY SKIES ARE PRESENT THIS MORNING ACROSS PORTIONS OF
CENTRAL NY AND NORTHEAST PA. PATCHY FOG HAVE DEVELOP ALONG THE
VALLEYS. EXPECT FOG TO LIFT WITHIN THE NEXT COUPLE OF HOURS.
SHOWERS HAVE ALSO DEVELOPED ACROSS WESTERN NY AND PA. EXPECT THESE
TO DRIFT TO THE EAST AROUND 15-20 MPH. MADE MINOR ADJUSTMENTS TO
THE PREVIOUS FORECAST. FOR MORE INFORMATION ON TODAY`S EVENT...
PLEASE READ DISCUSSION BELOW.
PREVIOUS FORECAST...
430 AM EDT UPDATE...
SHOWERS THIS MORNING HAVE PRETTY MUCH TAPERED OFF AND JUST AN
ISOLATED LIGHTNING STRIKE HERE ARE STILL GOING. PATCHY VALLEY FOG
HAVE ALSO DEVELOPED THIS MORNING AND EXPECT THIS TO MIX OUT
SHORTLY AFTER SUNRISE.
THE UPPR LEVEL LOW LOCATED OVER THE CENTRAL GREAT LAKES REGION
THAT HAVE BROUGHT US SHOWERS YESTERDAY WILL SLIGHTLY WEAKEN TODAY
AND DRIFT SLOWLY TOWARDS NY. AS THIS LOW DRIFTS TO THE SOUTH IT
WILL EJECT A VORTICITY MAXIMA ACROSS PORTIONS OF CENTRAL NY AND
NORTHEAST PA. THIS LOOKS LIKE IT WILL TRIGGER SHOWERS AND
THUNDERSTORMS ACROSS THE ARE LATE THIS MORNING/AFTERNOON.
ACTIVITY THAT DOES DEVELOPS TODAY WILL HAVE MORE INSTABILITY TO
WORK WITH THAN YESTERDAY. GUIDANCE IS INDICATING SBCAPE VALUES AROUND
2500 J/KG... BELIEVE THIS MAY BE A LITTLE HIGH BUT VALUES AROUND
1000 J/KG AREN`T TOO UNREASONABLE. 0-6KM BULK SHEAR VALUES ARE
EXPECTED TO BE AROUND 20 KNOTS OVER CENTRAL NY AND 30 OVER
NORTHEAST PA. A FEW STRONG STORMS MAY DEVELOP TOMORROW... AND ARE
EXPECTED TO BE MAINLY OVER NE PA WHERE THE SHEAR IS A LITTLE
STRONGER. WITH THE MENTIONED STATEMENTS ABOVE... EXPECT TO SEE
MORE CONVECTION OVERALL TODAY THAN PREVIOUS DAYS. THE BEST MID
LVL SUPPORT DURING THE TIME FRAME FOR LATE MORNING/AFTERNOON IS
EXPECTED TO BE I-81 AND EAST. PWAT VALUES TODAY ARE ALSO EXPECTED TO
BE AROUND 1.4 INCHES GIVE OR TAKE. WITH THAT BEING SAID WE COULD
SEE SOME LOCALIZED HEAVY RAINFALL RATES TODAY WITH THE CONVECTION.
TONIGHT THE UPPER LVL TROUGH WILL CONTINUE TO SHIFT EAST. SHOWERS MAY
LINGER THROUGH THE NIGHT AS WE MAY REMAIN UNDER CYCLONIC FLOW TILL
LATE IN THE NIGHT. THE TROUGH AXIS IS EXPECTED TO BE LOCATED OVER
CENTRAL NY BY LATE THURSDAY NIGHT/FRIDAY MORNING. DEPENDING ON HOW
QUICKLY THE AXIS MOVES EAST WILL DEPEND ON HOW LONG SHOWERS MAY
LINGER.
TEMPS ARE EXPECTED TO RISE INTO THE 70S AND ISOLATED SPOTS IN THE
80S THIS AFTERNOON AS 850MB TEMPS REMAIN NEAR 14 DECREES CELSIUS.
TEMPS TONIGHT ARE EXPECTED TO REMAIN IN THE 60S AS DENSE CLOUD
COVERAGE WILL INHIBIT STRONG COOLING.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
430 AM EDT UPDATE...
BY FRIDAY THE UPPR LVL TROUGH WILL BE EAST OF THE AREA AND
THE LARGE RIDGE CURRENTLY CENTERED OVER THE SOUTHERN CONUS WILL
MOVE EAST AND BECOME SLIGHTLY AMPLIFIED OVER THE MID-WEST. THIS
WILL RESULT IN OUR PATTERN ALOFT TRANSITIONING TO A NORTHWESTERLY
FLOW. WEAK SPURTS OF ENERGY WILL SLIDE SOUTH INTO OUR AREA ON
FRIDAY AND DUE TO THE COMBINATIONS OF LINGERING LOW LVL
MOISTURE... WEAK WAVES... AND HEATING FROM THE SUN... SHOWERS AND
THUNDERSTORMS MAY DEVELOP ACROSS THE AREA.
LATE FRIDAY NIGHT/SATURDAY MORNING WEAK VORTICITY MAXES WILL
TRAVEL ALONG THE OUTER EDGE OF THE RIDGE ALOFT AND MAY GENERATE
SOME SHOWERS OVER THE WESTERN CWA. BUT... BY SATURDAY AFTERNOON
THE UPPR RIDGE WILL BE FURTHER EAST AND SUBSIDENCE WILL START TO
TAKE CONTROL OF THE AREA. THIS WILL CREATE AN ENVIRONMENT THAT WILL
EVENTUALLY INHIBIT CONVECTIVE DEVELOPMENT. THUS... BY SATURDAY
EVENING THE CHANCE FOR SHOWERS WILL BE GONE.
TEMPERATURES DURING THIS TIME FRAME WILL RISE INTO THE 70S EACH
AFTERNOON AND FALL INTO THE LOW TO MID 50S EACH MORNING.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
3 AM UPDATE...MEDIUM RANGE MODELS INDICATE A STRONG UPPER LEVEL
RIDGE WILL EXTEND FROM THE GULF STATES NORTH INTO THE LOCAL AREA.
THIS COMBINED WITH SFC HIGH PRES ALONG THE NEW ENGLAND COAST WILL
PROVIDE A PLEASANT STRETCH OF DRY WEATHER WITH TEMPS RUNNING A FEW
DEGREES ABOVE SEASONAL NORMALS. BY LATE WEDNESDAY INTO WEDNESDAY
NIGHT AN UPPER LEVEL TROF AND ASSOCIATED SFC FRONT MAY BRING THE
AREA SOME SHOWERS.
245 PM UPDATE...
WPC GUIDANCE LOOKS FINE FOR THE EXTENDED FORECAST WITH DRY WEATHER
EXPECTED. A LARGE RIDGE OF HIGH PRESSURE ALOFT, WITH 588 DM
HEIGHTS WILL SPREAD INTO THE LOWER GREAT LAKES. SUNDAY THROUGH
EARLY NEXT WEEK WE WILL SEE THE IMPACTS OF THIS RIDGE WITH VERY
QUIET WEATHER. WITH A NORTHERLY TO NORTHEAST FLOW ALOFT AND NEAR
THE SURFACE IT WILL BE COMFORTABLE WITH HIGHS NEAR 80 AND
COMFORTABLE NIGHTS. FARTHER DOWN THE ROAD AS THE RIDGE MOVES EAST,
OUR FLOW ALOFT WILL BECOME MORE SOUTHWESTERLY. EVENTUALLY THIS
SHOULD TRANSLATE INTO MUCH, MUCH WARMER AIR BY THE MIDDLE OF NEXT
WEEK.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
MOST TERMINALS ARE VFR EARLY THIS MORNING WITH THE EXCEPTION OF
KELM WHERE CONDITIONS NEAR AIRPORT MINS WILL CONTINUE UNTIL 14Z
AND KBGM WHERE LOW MVFR CIGS WILL PERSIST UNTIL 14Z. BY MID
MORNING CONDITIONS WILL REMAIN VFR UNTIL WIDESPREAD CONVECTION
DEVELOPS THIS AFTERNOON IN RESPONSE TO A MID LEVEL SHORT WAVE
ROTATING AROUND THE UPPER LEVEL LOW OVER THE EASTERN LAKES.
SHOWERS AND EMBEDDED THUNDERSTORMS ARE LIKELY THIS AFTERNOON INTO
THE EARLY EVENING. FOR THE NYS TERMINALS INCLUDED PREVAILING MVFR
SHOWERS FROM 18Z-00Z, AT KAVP 21Z-03Z. MVFR RESTRICTIONS WILL
CONTINUE THIS EVENING AGAIN DUE TO RAINFALL AND WEAK MIXING. AT
KELM DENSE FOG WILL BE LIKELY ONCE AGAIN AFTER 06Z.
LIGHT WINDS BECOMING SOUTHWEST AROUND 5 KNOTS THIS MORNING THEN
LIGHT AGAIN TONIGHT.
OUTLOOK...
FRIDAY TO FRI NGT...MVFR RESTRICTIONS POSSIBLE IN AFTN SHRA/TSRA.
FRI NGT...IFR FOG AND STRATUS POSSIBLE.
SAT-MON...VFR EXCEPT SOME IFR POSSIBLE IN EARLY FOG AT KELM.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...KAH
NEAR TERM...KAH/PVN
SHORT TERM...KAH
LONG TERM...HEDEN/RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1045 AM EDT THU AUG 21 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW
ALOFT WILL CROSS THE REGION THROUGH LATE WEEK. A BACK DOOR COLD
FRONT IS FORECAST TO SLIP INTO THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM WEDNESDAY...
NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY
OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH
IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE
WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY
ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND
DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER
DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE
IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE
PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS
CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING
AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS
BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER
EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL
BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST
OF US 1.
OVERNIGHT LOWS IN THE LOWER 70S.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 320 AM THURSDAY...
UPPER RIDGE OVER THE CENTRAL US CONTINUES TO AMPLIFY AS THE UPPER
TROUGH MOVES OFF THE MID-ATLANTIC COAST. WHILE THERE CONTINUES TO
BE CONSIDERABLE RUN-TO-RUN VARIABILITY WITH HOW NWP GUIDANCE HANDLE
INDIVIDUAL SHORTWAVES EMBEDDED IN THE MEAN TROUGH...THE OVERRIDING
THEME OVER THE LAST SEVERAL DAYS HAS BEEN RATHER CONSISTENT IN
SHOWING AN INCREASE/UPTICK IN RAIN CHANCES/POPS LATE FRIDAY AND INTO FRIDAY
NIGHT IN RESPONSE TO THE BROADER SYNOPTIC SCALE ASCENT MOVING DOWN
THE MID-ATLANTIC COAST AND ATTENDANT BACK-DOOR FRONTAL INTO THE
AREA. WILL MAINTAIN CURRENT POP CONFIGURATION WITH HIGH CHANCE POPS
ACROSS THE NORTH INVOF OF THE BETTER FORCING AND LOW CHANCE POPS
SOUTH.
A TOUCH COOLER ON FRIDAY AS HEIGHTS LOWER ALOFT COMBINED WITH AN
INCREASE IN CLOUD COVER AND RAIN CHANCES. HIGHS IN THE LOWER 90S
NORTH TO MID 90S SOUTH. LOWS FRIDAY NIGHT IN THE UPPER 60S TO LOWER
70S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...
THE LONG TERM PERIOD WILL BE CHARACTERIZED BY A BUILDING UPPER RIDGE
ACROSS THE MISSISSIPPI RIVER VALLEY WITH AN UPPER TROUGH/CLOSED LOW
OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER A NORTHWESTERLY
UPPER FLOW REGIME. THIS UPPER RIDGE IS PROGGED TO SHIFT EAST TOWARDS
THE REGION BY THE MIDDLE OF NEXT WEEK. AS THE SURFACE...A BACKDOOR
COLD FRONT WILL BE SLIPPING FURTHER TO OUR SOUTH AND WEST THROUGH
THE DAY ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED OVER THE
REGION THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND AND GIVEN THIS
SURFACE BOUNDARY AND ANY DISTURBANCES ALOFT WITHIN THE NORTHWESTERLY
FLOW...PRECIP CHANCES WILL BE THE HIGHEST ON SATURDAY. THE DEEP
MOISTURE BEGINS TO GET SHUNTED TO OUR SOUTHWEST ON SUNDAY...BUT
ESPECIALLY INTO EARLY NEXT WEEK. THIS WILL RESULT IN DECREASING
PRECIP CHANCES AND IN FACT HAVE REMOVED MENTION OF PRECIP FROM THE
FORECAST BY THE EARLY TO MIDDLE PART OF NEXT WEEK...ESPECIALLY GIVEN
THAT THE UPPER RIDGE WILL BUILD TOWARDS THE AREA.
LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT
WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN
ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE
RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN
BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY AND
UPPER 70S TO LOW/MID 80S EXPECTED FOR SUNDAY AND EARLY NEXT WEEK.
TEMPS WILL BEGIN TO MODERATE TUESDAY AND ESPECIALLY INTO WEDNESDAY
AS THE UPPER RIDGE SHIFTS EAST. OVERNIGHT LOWS WILL INITIALLY BE IN
THE UPPER 60S TO LOWER 70S...WITH SLIGHTLY COOLER TEMPS FOR THE
REMAINDER OF THE PERIOD (MOSTLY MID/UPPER 60S WITH SOME LOWER 60S IN
THE COOLER LOCATIONS).
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 715 AM THURSDAY...
ANY SUB-VFR CONDITIONS WILL AGAIN LIFT TO VFR BY MID TO LATE MORNING
AT THE LATEST... WITH THE PROSPECTS OF VFR CONDITIONS BY 13-15Z AT
ALL TAF SITES. ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS WILL
BE POSSIBLE AGAIN ON THURSDAY ACROSS ALL OF CENTRAL NC. HOWEVER...
THE PROBABILITY AT A GIVEN SITE IS TOO LOW TO INCLUDE IN THE TAFS AT
THIS TIME.
OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS
AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD
FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING
ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...CBL/BLS
SHORT TERM...CBL
LONG TERM...KRD
AVIATION...CBL/BLS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1145 AM EDT THU AUG 21 2014
.SYNOPSIS...
A WARM FRONT WILL PIVOT INTO CENTRAL PENNSYLVANIA THROUGH
TONIGHT. UPPER TROUGHING MOVING EAST FROM THE GREAT LAKES ACROSS
THE NORTHEAST STATES INTO THE CANADIAN MARITIME REGION WILL PUSH
THE FRONT BACK TO THE SOUTH ALONG THE EAST COAST THIS
WEEKEND...ALLOWING A LARGE AREA OF HIGH PRESSURE OVER NORTHERN
NEW ENGLAND TO RIDGE SOUTHWEST ALONG THE EAST-SIDE OF THE
APPALACHIANS THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
ISOLATED TO LOCALLY SCATTERED COVERAGE OF SHOWERS EXPECT THIS
AFTERNOON AS BROAD UPPER SHEAR AXIS LIES ACROSS PA. PW IS MUCH
LOWER THAN YESTERDAY...ALONG WITH STRONGER NW FLOW ALOFT. THESE
TWO FACTORS SHOULD RESULT IN LITTLE CONCERN FOR HEAVY RAINERS THIS
AFTERNOON...AND JUST GENERIC OVERALL SHOWER/THUNDERSTORM CHANCES
THROUGH THIS EVENING.
A MOIST/MODESTLY UNSTABLE AIRMASS AND RELATIVELY STEEP MID LVL
LAPSE RATES WILL YIELD HIGHEST POPS /40-60%/ DURING PEAK HEATING
IN THE 18-00Z TIME WINDOW. HRRR IS LESS THAN IMPRESSIVE...
GENERALLY INDICATING ISOLATED TO SCATTERED COVERAGE IN MOST
PLACES.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
UPPER LOW WILL BE PASSING INTO NEW ENG BY FRI MORNING.
HOWEVER..SHORT TERM MDL DATA ALL TRACKING A TRAILING SHORTWAVE SEWRD
THRU CENTRAL PA FRIDAY PM...WHICH WILL LIKELY BRING ANOTHER ROUND OF
SHRA/TSRA TO THE AREA. HIGHEST /LIKELY/ POPS PLACED ALONG AND SW OF
QUASI-STATIONARY FRONT...WHICH MDLS PLACE ROUGHLY FROM KBFD SE TO
KTHV. SOUTH AND WEST OF THIS BNDRY...UNSTABLE SOUNDINGS AND HIGH
PWATS COULD RESULT IN LOCALLY HVY RAINFALL IN TSRA. CONVECTION-
ALLOWING MDLS PRODUCING ISOLATED SPOTS AMTS OF ARND 4 INCHES.
HOWEVER...AVERAGE AMTS BASED ON BLENDED QPF SHOULD BE LESS THAN A
HALF INCH. GEFS 925 TEMPS ARE SUPPORTIVE OF MAX TEMPS NR SEASONAL
LEVELS FRIDAY.
CONVECTION SHOULD DIMINISH AND PUSH SOUTH OF THE STATE FRIDAY
NIGHT...AS SHORTWAVE DIVES SOUTH OF THE AREA. BEHIND THIS
FEATURE...BACKDOOR COLD FRONT IS PROGGED TO WORK SWRD THRU CENTRAL
PA FRI NIGHT. MOIST EASTERLY FLOW ASCENDING THE APPALACHIANS MAY
PRODUCE LOW CLOUDS AND SPOTTY DRIZZLE LATE FRIDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
LARGE SFC HIGH OVR NEW ENG WILL BE THE PRIMARY DRIVER OF OUR WX THRU
MOST OF THE EXTENDED FCST. MOIST...EASTERLY FLOW OFF THE ATLANTIC
WILL LIKELY PRODUCE A DULL AND COOL SATURDAY...WITH AM LOW CLOUDS
GIVING WAY TO A BIT OF BRIGHTENING BY AFTN. GEFS 925 TEMPS OF ONLY
16C-18C IMPLY MAX TEMPS FROM JUST THE U60S OVR THE HIGH TERRAIN OF
THE CENTRAL MTNS...TO THE M70S OVR THE SUSQ VALLEY.
MED RANGE GUIDANCE INDICATES HIGH PRES AND ASSOC DRY AIR MASS WILL
DRIFT SOUTH LATE THIS WEEKEND...BRINGING FAIR AND BRIGHTER WX TO
CENTRAL PA. PTSUNNY SKIES SHOULD HELP TEMPS REBOUND A BIT ON
SUNDAY...BUT STILL REMAIN BLW NORMAL.
EARLIER CONCERNS OF CENTRAL PA DEALING WITH RING OF FIRE CONVECTION
APPEAR TO BE WANING...AS LARGE SCALE SUBSIDENCE AND DRY AIR ARE THE
THEMES OF THE MED RANGE GUIDANCE EARLY NEXT WEEK BENEATH SFC RIDGE
ALONG THE E COAST. FCST CONFIDENCE BEGINS LOWER BY THE MIDDLE OF
NEXT WEEK...WHEN MED RANGE MDLS BEGIN TO DIVERGE. GEFS KEEPS RIDGE
AND FAIR WX GOING THRU WED...WHILE ECMWF ENSEMBLE DATA INDICATES A
WEAK COLD FRONT COULD PUSH SE INTO THE REGION. THUS...HAVE ADDED A
LOW CHC OF TSRA WED. WHAT APPEARS CERTAIN IS THAT THE COOL TEMPS OF
THIS WEEKEND WILL GIVE WAY TO A SLOW WARMING TREND THRU THE FIRST
HALF OF NEXT WEEK...AS COOL AIR MASS MODIFIES UNDER STILL STRONG
AUGUST SUN. GEFS AND EC ENS 850 TEMPS SUPPORT HIGH RETURNING TO ABV
NORMAL BY WED.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
HI RES MODELS CONT TO DEPICT ISOLD SHRA AND TSTMS OVER CENTRAL PA
THIS AFTERNOON. SPARSE COVERAGE RESULTS IN LOW CONFIDENCE IN
POINT TERMINAL IMPACTS...SO WILL INDICATE VCSH MENTION THROUGH
THIS EVENING.
ANTICIPATE DECREASING COVERAGE OF SHRA AND TSTMS INTO THE
EVE/OVERNIGHT PERIOD WITH AREAS OF FOG/ST POSSIBLY RE- DEVELOPING
WITH SOME CLEARING/LGT WINDS/MOIST AIRMASS ESP IN THE NORTH. WILL
NEED TO WATCH UPSTREAM IN THE OH VLY FOR POSSIBLE CONVECTIVE
COMPLEX. FOR NOW EXPECT THIS MESOSCALE SYSTEM TO STAY SW OF THE
AIRSPACE FROM OH TO WV.
OUTLOOK...
FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF
MVFR/IFR RESTRICTIONS.
SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...DEVOIR/STEINBUGL
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...DEVOIR/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1129 AM EDT THU AUG 21 2014
.SYNOPSIS...
A WARM FRONT WILL PIVOT INTO CENTRAL PENNSYLVANIA THROUGH
TONIGHT. UPPER TROUGHING MOVING EAST FROM THE GREAT LAKES ACROSS
THE NORTHEAST STATES INTO THE CANADIAN MARITIME REGION WILL PUSH
THE FRONT BACK TO THE SOUTH ALONG THE EAST COAST THIS
WEEKEND...ALLOWING A LARGE AREA OF HIGH PRESSURE OVER NORTHERN
NEW ENGLAND TO RIDGE SOUTHWEST ALONG THE EAST-SIDE OF THE
APPALACHIANS THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
ISOLATED TO LOCALLY SCATTERED COVERAGE OF SHOWERS EXPECT THIS
AFTERNOON AS BROAD UPPER SHEAR AXIS LIES ACROSS PA. PW IS MUCH
LOWER THAN YESTERDAY...ALONG WITH STRONGER NW FLOW ALOFT. THESE
TWO FACTORS SHOULD RESULT IN LITTLE CONCERN FOR HEAVY RAINERS THIS
AFTERNOON...AND JUST GENERIC OVERALL SHOWER/THUNDERSTORM CHANCES
THROUGH THIS EVENING.
A MOIST/MODESTLY UNSTABLE AIRMASS AND RELATIVELY STEEP MID LVL
LAPSE RATES WILL YIELD HIGHEST POPS /40-60%/ DURING PEAK HEATING
IN THE 18-00Z TIME WINDOW. HRRR IS LESS THAN IMPRESSIVE...
GENERALLY INDICATING ISOLATED TO SCATTERED COVERAGE IN MOST
PLACES.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
UPPER LOW WILL BE PASSING INTO NEW ENG BY FRI MORNING.
HOWEVER..SHORT TERM MDL DATA ALL TRACKING A TRAILING SHORTWAVE SEWRD
THRU CENTRAL PA FRIDAY PM...WHICH WILL LIKELY BRING ANOTHER ROUND OF
SHRA/TSRA TO THE AREA. HIGHEST /LIKELY/ POPS PLACED ALONG AND SW OF
QUASI-STATIONARY FRONT...WHICH MDLS PLACE ROUGHLY FROM KBFD SE TO
KTHV. SOUTH AND WEST OF THIS BNDRY...UNSTABLE SOUNDINGS AND HIGH
PWATS COULD RESULT IN LOCALLY HVY RAINFALL IN TSRA. CONVECTION-
ALLOWING MDLS PRODUCING ISOLATED SPOTS AMTS OF ARND 4 INCHES.
HOWEVER...AVERAGE AMTS BASED ON BLENDED QPF SHOULD BE LESS THAN A
HALF INCH. GEFS 925 TEMPS ARE SUPPORTIVE OF MAX TEMPS NR SEASONAL
LEVELS FRIDAY.
CONVECTION SHOULD DIMINISH AND PUSH SOUTH OF THE STATE FRIDAY
NIGHT...AS SHORTWAVE DIVES SOUTH OF THE AREA. BEHIND THIS
FEATURE...BACKDOOR COLD FRONT IS PROGGED TO WORK SWRD THRU CENTRAL
PA FRI NIGHT. MOIST EASTERLY FLOW ASCENDING THE APPALACHIANS MAY
PRODUCE LOW CLOUDS AND SPOTTY DRIZZLE LATE FRIDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
LARGE SFC HIGH OVR NEW ENG WILL BE THE PRIMARY DRIVER OF OUR WX THRU
MOST OF THE EXTENDED FCST. MOIST...EASTERLY FLOW OFF THE ATLANTIC
WILL LIKELY PRODUCE A DULL AND COOL SATURDAY...WITH AM LOW CLOUDS
GIVING WAY TO A BIT OF BRIGHTENING BY AFTN. GEFS 925 TEMPS OF ONLY
16C-18C IMPLY MAX TEMPS FROM JUST THE U60S OVR THE HIGH TERRAIN OF
THE CENTRAL MTNS...TO THE M70S OVR THE SUSQ VALLEY.
MED RANGE GUIDANCE INDICATES HIGH PRES AND ASSOC DRY AIR MASS WILL
DRIFT SOUTH LATE THIS WEEKEND...BRINGING FAIR AND BRIGHTER WX TO
CENTRAL PA. PTSUNNY SKIES SHOULD HELP TEMPS REBOUND A BIT ON
SUNDAY...BUT STILL REMAIN BLW NORMAL.
EARLIER CONCERNS OF CENTRAL PA DEALING WITH RING OF FIRE CONVECTION
APPEAR TO BE WANING...AS LARGE SCALE SUBSIDENCE AND DRY AIR ARE THE
THEMES OF THE MED RANGE GUIDANCE EARLY NEXT WEEK BENEATH SFC RIDGE
ALONG THE E COAST. FCST CONFIDENCE BEGINS LOWER BY THE MIDDLE OF
NEXT WEEK...WHEN MED RANGE MDLS BEGIN TO DIVERGE. GEFS KEEPS RIDGE
AND FAIR WX GOING THRU WED...WHILE ECMWF ENSEMBLE DATA INDICATES A
WEAK COLD FRONT COULD PUSH SE INTO THE REGION. THUS...HAVE ADDED A
LOW CHC OF TSRA WED. WHAT APPEARS CERTAIN IS THAT THE COOL TEMPS OF
THIS WEEKEND WILL GIVE WAY TO A SLOW WARMING TREND THRU THE FIRST
HALF OF NEXT WEEK...AS COOL AIR MASS MODIFIES UNDER STILL STRONG
AUGUST SUN. GEFS AND EC ENS 850 TEMPS SUPPORT HIGH RETURNING TO ABV
NORMAL BY WED.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
FOG AND LOW CLOUDS /IFR-LIFR CONDITIONS/ WILL GIVE WAY TO VFR BY
13-14Z. LATEST COSPA/HRRR INDICATES MORE DISORGANIZED WDLY SCT
SHRA AND TSTMS DEVELOPING THIS AFTN/MAINLY AFTER 17Z. EXPECTED
SPARSE COVERAGE/LOW CONFIDENCE IN POINT-TERMINAL IMPACTS WILL
LIMIT VCTS MENTION ATTM...AND WILL ALLOW THIS TO BE ADDRESSED WITH
THE 15Z INTERMEDIATE UPDATE AND 18Z SCHEDULED ISSUANCE. ANTICIPATE
DECREASING COVERAGE OF SHRA AND TSTMS INTO THE EVE/OVERNIGHT
PERIOD WITH AREAS OF FOG/ST POSSIBLY RE-DEVELOPING WITH SOME
CLEARING/LGT WINDS/MOIST AIRMASS ESP IN THE NORTH. WILL NEED TO
WATCH UPSTREAM IN THE OH VLY FOR POSSIBLE CONVECTIVE COMPLEX. FOR
NOW EXPECT THIS MESOSCALE SYSTEM TO STAY SW OF THE AIRSPACE FROM
OH TO WV.
OUTLOOK...
FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF
MVFR/IFR RESTRICTIONS.
SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...DEVOIR/STEINBUGL
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1051 AM CDT THU AUG 21 2014
.DISCUSSION...
PER TRENDS SO FAR THIS MORNING IT LOOKS LIKE THE SLUG OF DEEPER
TROPICAL MOISTURE HAS SHIFTED TO THE EAST AND THINGS ARE DRYING
OUT ACROSS MOST OF OUR CWA. NO CHANGES PLANNED ATTM AS THE CUR-
RENT FCST LOOKS TO BE ON TRACK. 41
&&
.PREV DISCUSSION... /ISSUED 347 AM CDT THU AUG 21 2014/
SOME OBSERVATIONS ARE NOW INDICATING LOW CLOUDS STARTING TO FORM
TONIGHT. THESE WILL QUICKLY BURN OFF THIS AFTERNOON ALLOWING FOR
ANOTHER HOT AND MUGGY DAY. CHANCE OF RAIN TODAY WILL BE FAR LESS
THAN YESTERDAY. AT 250 MB BEST UPPER LEVEL DIFFLUENCE IS OFF TO
THE EAST OF THE AREA THANKS TO AN UPPER LEVEL RIDGE MOVING INTO
CENTRAL TEXAS. AT 500 MB HEIGHTS HAVE ALSO STARTED TO RISE ACROSS
SOUTHEAST TEXAS THANKS TO A BUILDING RIDGE. THE RAP PERFORMED
PRETTY WELL YESTERDAY AND SHOWS ALMOST NO RAIN FOR SOUTHEAST TEXAS
EXCEPT FOR A SPOTTY SHOWER OR TWO IN SAN JACINTO AND LIBERTY
COUNTIES LATER THIS AFTERNOON. THE TEXAS TECH WRF ALSO SHOWS THIS.
GIVEN THE EVIDENCE FROM THE UPPER LEVEL MAPS MENTIONED ABOVE THIS
MAKES SENSE.
THE UPPER LEVEL RIDGE WILL CONTINUE TO BUILD AND POSITION ITSELF
NEAR THE ARKANSAS/ LOUISIANA BORDER ON FRIDAY. THE HEAT ADVISORY
WILL LIKELY BE NEEDED THROUGH THE WEEKEND. BY SUNDAY THE RIDGE
WILL BEGIN TO WEAKEN. GFS FORECAST SOUNDINGS STILL SHOW RELATIVELY
LOW PWAT AIR IN PLACE FOR THIS TIME OF YEAR AND A CAP IN PLACE AT
850MB. ON MONDAY THE CAP WEAKENS ENOUGH TO INTRODUCE THE CHANCE OF
RAIN BACK INTO THE FORECAST. THE CHANCE OF AFTERNOON SHOWERS AND
THUNDERSTORMS AND ABOVE NORMAL TEMPERATURES LOOKS TO REMAIN IN
PLACE THROUGH NEXT WEDNESDAY. 23
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 77 99 77 99 / 10 10 10 10 10
HOUSTON (IAH) 97 77 97 77 97 / 10 10 10 10 10
GALVESTON (GLS) 92 84 92 84 92 / 20 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON...
MATAGORDA.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
612 AM CDT THU AUG 21 2014
.DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
&&
.AVIATION...
NO SIGNIFICANT CHANGES TO PREV TAF PACKAGE. FCST SOUNDINGS
INDICATE DRIER CONDS WITH PW VALUES DROPPING TO 1.5-1.7 INCHES.
RAP/HRRR KEEP MOST OF THE PRECIP TO THE EAST TODAY AS WELL. MVFR
CIGS WILL BE POSSIBLE EARLY THIS MORNING WITH CIGS MIXING OUT
BETWEEN 14-16Z. SHOULD GET SOME MVFR CIGS AGAIN OVER THE NW TAF
SITES AGAIN TOMORROW MORNING. 43
&&
.PREV DISCUSSION... /ISSUED 347 AM CDT THU AUG 21 2014/
DISCUSSION...
SOME OBSERVATIONS ARE NOW INDICATING LOW CLOUDS STARTING TO FORM
TONIGHT. THESE WILL QUICKLY BURN OFF THIS AFTERNOON ALLOWING FOR
ANOTHER HOT AND MUGGY DAY. CHANCE OF RAIN TODAY WILL BE FAR LESS
THAN YESTERDAY. AT 250 MB BEST UPPER LEVEL DIFFLUENCE IS OFF TO
THE EAST OF THE AREA THANKS TO AN UPPER LEVEL RIDGE MOVING INTO
CENTRAL TEXAS. AT 500 MB HEIGHTS HAVE ALSO STARTED TO RISE ACROSS
SOUTHEAST TEXAS THANKS TO A BUILDING RIDGE. THE RAP PERFORMED
PRETTY WELL YESTERDAY AND SHOWS ALMOST NO RAIN FOR SOUTHEAST TEXAS
EXCEPT FOR A SPOTTY SHOWER OR TWO IN SAN JACINTO AND LIBERTY
COUNTIES LATER THIS AFTERNOON. THE TEXAS TECH WRF ALSO SHOWS THIS.
GIVEN THE EVIDENCE FROM THE UPPER LEVEL MAPS MENTIONED ABOVE THIS
MAKES SENSE.
THE UPPER LEVEL RIDGE WILL CONTINUE TO BUILD AND POSITION ITSELF
NEAR THE ARKANSAS/ LOUISIANA BORDER ON FRIDAY. THE HEAT ADVISORY
WILL LIKELY BE NEEDED THROUGH THE WEEKEND. BY SUNDAY THE RIDGE
WILL BEGIN TO WEAKEN. GFS FORECAST SOUNDINGS STILL SHOW RELATIVELY
LOW PWAT AIR IN PLACE FOR THIS TIME OF YEAR AND A CAP IN PLACE AT
850MB. ON MONDAY THE CAP WEAKENS ENOUGH TO INTRODUCE THE CHANCE OF
RAIN BACK INTO THE FORECAST. THE CHANCE OF AFTERNOON SHOWERS AND
THUNDERSTORMS AND ABOVE NORMAL TEMPERATURES LOOKS TO REMAIN IN
PLACE THROUGH NEXT WEDNESDAY. 23
MARINE...
MODERATE ONSHORE WINDS WILL PERSIST THROUGH TONIGHT AND BEGIN TO
RELAX BY FRIDAY MORNING. WILL MAINTAIN THE SCEC FOR THE GULF WATERS
THROUGH THE EARLY MORNING. SURFACE HIGH PRESSURE WILL BE CENTERED
OVER THE WESTERN GULF BY SUNDAY MORNING AND THE PRESSURE GRADIENT
WILL SLACKEN CONSIDERABLY. LIGHT WINDS ARE EXPECTED OVER THE WEEKEND
AND INTO THE FIRST HALF OF NEXT WEEK. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 77 99 77 99 / 10 10 10 10 10
HOUSTON (IAH) 97 77 97 77 97 / 10 10 10 10 10
GALVESTON (GLS) 92 84 92 84 92 / 20 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON...
MATAGORDA.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 10 AM CDT THIS MORNING
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS ALBANY NY
638 PM EDT THU AUG 21 2014
.SYNOPSIS...
A SLOW MOVING UPPER LEVEL LOW OVER THE EASTERN GREAT LAKES REGION
WILL CONTINUE TO BRING SHOWERS AND THUNDERSTORMS...SOME WITH LOCALLY
HEAVY RAIN...AS IT DRIFTS EASTWARD THROUGH TONIGHT. THE UPPER LEVEL
LOW WILL TRACK OFF THE COAST TOMORROW WITH A FEW LINGERING SHOWERS
AND COOL TEMPERATURES OVER THE AREA. IMPROVING CONDITIONS ARE
EXPECTED OVER THE WEEKEND AS HIGH PRESSURE BUILDS AT ALL LEVELS OF
THE ATMOSPHERE FROM QUEBEC INTO THE NORTHEAST. IT WILL BRING INCREASING
AMOUNTS OF SUNSHINE AND WARMER TEMPERATURES INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 357 PM EDT...AN UPPER LEVEL LOW IS CURRENTLY SITUATED WEST OF
THE REGION JUST TO THE NORTH OF LAKE ONTARIO. WITH A MOIST AIR MASS
IN PLACE...THERE IS PLENTY OF FORCING IN PLACE TO ALLOW FOR
SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS THE REGION THROUGH
THE EVENING HOURS..
WITH PLENTY OF CLOUD COVER IN PLACE...INSTABILITY IS
LIMITED...WHICH IS HELPING KEEP THE THREAT FOR SEVERE WEATHER LOW.
HOWEVER...WITH PWATS ABOVE NORMAL /AROUND 1.63 INCHES FROM THIS
MORNINGS KALY SOUNDING/...DEW POINTS INTO THE 60S...AND HIGH FZL
LEVELS /FZL LEVELS AROUND 12000 FT/....THE THREAT FOR HEAVY
RAINFALL WILL BE POSSIBLE WITH ANY SHOWER OR THUNDERSTORM...AS
WARM RAIN PROCESSES WILL DOMINATE. THE RADAR HAS ALREADY SHOWN
SEVERAL SLOW MOVING LOW TOPPED STORMS...WITH HEAVY ECHOES LOCATED
TOWARDS THE BOTTOMS OF THE STORM...INDICATING HEAVY RAINFALL. THIS
WILL CONTINUE INTO THE EVENING HOURS...AS THE 3KM HRRR SHOWS
DISORGANIZED...BUT LOCALLY HEAVY...SHOWERS/THUNDERSTORMS TO MOVE
ACROSS THE REGION FROM WEST TO EAST THROUGH THE LATE EVENING
HOURS. WE WILL CONTINUE TO MONITOR FOR THE POTENTIAL FOR LOCALIZED
FLOODING. SEE OUR HYDRO DISCUSSION FOR MORE DETAILS.
POPS GRADUALLY TAPER DOWN TO CHANCE FOR LATE TONIGHT AS THE CORE
OF THE UPPER LEVEL LOW MOVES OVERHEAD...AND THE BEST FORCING
STARTS TO SHIFT EAST OF THE AREA. HOWEVER...IT STILL LOOKS TO
REMAIN CLOUDY THROUGH THE OVERNIGHT HOURS...WITH MIN TEMPS MAINLY
IN THE UPPER 50S TO MID 60S.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
TOMORROW...THE UPPER LEVEL LOW WILL START TO SHIFT OFFSHORE.
HOWEVER...CYCLONIC FLOW AROUND THIS SYSTEM WILL CONTINUE TO ALLOW
FOR THE THREAT FOR SOME SCATTERED SHOWERS...ESP DURING DAYTIME
HEATING. ANY RAINFALL WILL BE MUCH LIGHTER ON FRIDAY...AS THE BEST
MOISTURE WILL BE STARTING TO SHIFT SOUTH AND EAST TOWARDS
SOUTHERN NEW ENGLAND. IT STILL LOOKS TO STAY FAIRLY CLOUDY WITH
THE UPPER LOW NEARBY...SO TEMPS WILL BE HELD DOWN. MAX TEMPS WILL
ONLY BE IN THE UPPER 60S TO MID 70S.
THE UPPER LEVEL LOW WILL CONTINUE TO MOVE AWAY FROM THE REGION
BETWEEN FRIDAY NIGHT AND SATURDAY. A LINGERING SPRINKLE OR SHOWER
CANNOT TOTALLY BE RULED OUT OVER THE HIGH TERRAIN...OTHERWISE IT
LOOKS TO BE DRY. FINALLY...SOME BREAKS IN THE CLOUDS WILL START TO
OCCUR...ESP BY SAT MORNING FROM NORTH TO SOUTH...AS DRIER AIR
STARTS TO WORK IN FROM SOUTHERN CANADA. MIN TEMPS FRI NIGHT WILL
BE IN THE 50S...WITH HIGHS ON SATURDAY IN THE 70S.
UPPER LEVEL RIDGING WILL START TO BUILD INTO THE AREA FOR SATURDAY
NIGHT FROM THE GREAT LAKES AND OHIO VALLEY. WITH CLEARING SKIES
AND LIGHT WINDS...GOOD RADIATIONAL COOLING CAN BE
EXPECTED...ALLOWING FOR TEMPS TO FALL EASILY. OVERNIGHT LOWS WILL
RANGE FROM THE UPPER 40S OVER THE ADIRONDACKS TO THE MID 50S IN
THE CAPITAL REGION AND MID HUDSON VALLEY.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE DOMINATES THE WEATHER OVER THE REGION SUNDAY THROUGH
WEDNESDAY WITH GRADUAL WARMING EACH DAY AS THE HIGH PRESSURE BUILDS
OFFSHORE. HIGHS SUNDAY AND MONDAY IN THE MID 70S TO LOWER 80S. HIGHS
TUESDAY AND WEDNESDAY IN THE LOWER TO MID 80S...WITH UPPER 70S TO
LOWER 80S IN HIGHER TERRAIN.
A WEAK COLD FRONT JUST BEGINS TO APPROACH WEDNESDAY NIGHT AND
THURSDAY BUT THE LOW LEVEL THERMAL RIDGING SHOULD STILL BE IN PLACE.
SO...JUST SOME ISOLATED SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT
AND THURSDAY WITH HIGHS THURSDAY IN THE 80S.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
PRIMARY 500HPA SHORT WV IS MOVING INTO FCA W/ITS ASSOC WK SFC TROF...AND
SCT -SHRA/TSTMS ARE EVOLVING INTO MORE WIDESPREAD -SHRA...AND EMBEDDED
TSTMS AS THEY ARE MVNG INTO AREAS OF ELEVATED CAPE. CIGS AND OR
VSBYS WILL BE MVFR DURING THIS EVENING...WITH AREAS IFR IN TSTMS
THIS EVENING...BCMG IFR OVERNIGHT WITH LOWERING CIGS AND AREAS OF
FOG FORMING. WINDS WILL BE LIGHT NORTHEAST TO SOUTHEAST THIS
EVENING BCMG NEAR CALM OVERNIGHT.
FRI THE SFC TROF WILL LINGER NR WESTERN PERIPHERY OF FCA...AS SVRL
500HPA SHORT WVS DROP SE IN WAKE OF THE DEPARTING 500HPA CUTOFF.
SCT-BKN -SHRA WILL DIM THROUGH THE DAY AS DRIER AIR FILTERS IN
LLVLS FROM HIGH PRESSURE BUILDING SOUTH UNDER 500HPA RIDGE OVER
QB. WINDS WILL BCMG LIGHT NE. CIGS/VSBY WILL BE MVFR MUCH OF THE
DAY...IMPVG TO VFR TWRDS EVNG.
OUTLOOK...
FRIDAY NIGHT: LOW OPERATIONAL IMPACT. NO SIG WX.
SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SATURDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT WILL
KEEP FIRE WEATHER CONCERNS AT A MINIMUM. RH VALUES WILL BE NEAR
100 PERCENT IN MOST LOCATIONS TONIGHT. WITH CLOUDS AND SCATTERED SHOWERS
AROUND TOMORROW...RH VALUES WILL REMAIN ABOVE 70 PERCENT THROUGH
THE ENTIRE DAY...WITH LIGHT AND VARIABLE WINDS.
&&
.HYDROLOGY...
SHOWERS AND THUNDERSTORMS ARE CURRENTLY MOVING ACROSS THE REGION
THANKS TO A SLOW MOVING UPPER LEVEL LOW. THESE SHOWERS AND
THUNDERSTORMS ARE RATHER SLOW MOVING...AND WITH PWATS ABOVE NORMAL
/1.63 INCHES ON THIS MORNINGS 12Z KALY SOUNDING/...THERE IS THE
POTENTIAL FOR HEAVY RAIN IN A SHORT PERIOD OF TIME.
SOME AREAS...GENERALLY FROM AROUND AMSTERDAM NORTHEAST ACROSS THE
SACANDAGA LAKE AND INTO WESTERN SARATOGA COUNTY...SAW TWO TO FOUR
INCHES OF RAIN LAST NIGHT. ELSEWHERE...GROUND CONDITIONS HAVE BEEN
RATHER DRY...DUE TO A LACK OF RECENT RAINFALL. AS A RESULT...MOST
AREAS WILL BE ABLE TO HANDLE SOME RAINFALL. HOWEVER...IF HEAVY
RAIN OCCURS OVER THOSE AREAS THAT SAW RAINFALL LAST NIGHT OR IF
RAINFALL REPEATEDLY MOVES OVER THE SAME LOCATION THIS AFTN INTO
EVENING...THEN SOME MINOR FLOODING OF URBAN...POOR DRAINAGE AND
LOW LYING AREAS MAY OCCUR. AN ISOLATED FLASH FLOOD CANNOT TOTALLY
BE RULED OUT...ALTHOUGH ANY POSSIBLE FLOOD ISSUES WOULD LIKELY BE
MORE OF THE POOR DRAINAGE/URBAN TYPE CONCERNS.
THE THREAT FOR HEAVY RAINFALL WILL END TONIGHT...AS THE BEST
FORCING STARTS TO SHIFT AWAY FROM THE AREA. EVEN THOUGH THERE MAY
SOME LINGERING RAIN SHOWERS INTO TOMORROW...NO ADDITIONAL HEAVY
RAINFALL IS EXPECTED.
WHILE THERE MAY BE SOME RISES ON MAIN STREAM RIVERS DUE TO THE
RAINFALL...NO FLOODING OF LARGER RIVERS IS EXPECTED. WITH DRY
WEATHER RETURNING FOR SUNDAY INTO NEXT WEEK...RIVER LEVELS WILL
RECEDE AND/OR HOLD STEADY INTO NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS/SNYDER
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...IRL/SNYDER
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS ALBANY NY
357 PM EDT THU AUG 21 2014
.SYNOPSIS...
A SLOW MOVING UPPER LEVEL LOW OVER THE EASTERN GREAT LAKES REGION
WILL CONTINUE TO BRING SHOWERS AND THUNDERSTORMS...SOME WITH LOCALLY
HEAVY RAIN...AS IT DRIFTS EASTWARD THROUGH TONIGHT. THE UPPER LEVEL
LOW WILL TRACK OFF THE COAST TOMORROW WITH A FEW LINGERING SHOWERS
AND COOL TEMPERATURES OVER THE AREA. IMPROVING CONDITIONS ARE
EXPECTED OVER THE WEEKEND...WITH INCREASING AMOUNTS OF SUNSHINE AND
WARMER TEMPERATURES INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 357 PM EDT...AN UPPER LEVEL LOW IS CURRENTLY SITUATED WEST OF
THE REGION JUST TO THE NORTH OF LAKE ONTARIO. WITH A MOIST AIRMASS
IN PLACE...THERE IS PLENTY OF FORCING IN PLACE TO ALLOW FOR
SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS THE REGION THROUGH
THE EVENING HOURS..
WITH PLENTY OF CLOUD COVER IN PLACE...INSTABILITY IS
LIMITED...WHICH IS HELPING KEEP THE THREAT FOR SEVERE WEATHER LOW.
HOWEVER...WITH PWATS ABOVE NORMAL /AROUND 1.63 INCHES FROM THIS
MORNINGS KALY SOUNDING/...DEWPOINTS INTO THE 60S...AND HIGH FZL
LEVELS /FZL LEVELS AROUND 12000 FT/....THE THREAT FOR HEAVY
RAINFALL WILL BE POSSIBLE WITH ANY SHOWER OR THUNDERSTORM...AS
WARM RAIN PROCESSES WILL DOMINATE. THE RADAR HAS ALREADY SHOWN
SEVERAL SLOW MOVING LOW TOPPED STORMS...WITH HEAVY ECHOES LOCATED
TOWARDS THE BOTTOMS OF THE STORM...INDICATING HEAVY RAINFALL. THIS
WILL CONTINUE INTO THE EVENING HOURS...AS THE 3KM HRRR SHOWS
DISORGANIZED...BUT LOCALLY HEAVY...SHOWERS/THUNDERSTORMS TO MOVE
ACROSS THE REGION FROM WEST TO EAST THROUGH THE LATE EVENING
HOURS. WE WILL CONTINUE TO MONITOR FOR THE POTENTIAL FOR LOCALIZED
FLOODING. SEE OUR HYDRO DISCUSSION FOR MORE DETAILS.
POPS GRADUALLY TAPER DOWN TO CHANCE FOR LATE TONIGHT AS THE CORE
OF THE UPPER LEVEL LOW MOVES OVERHEAD...AND THE BEST FORCING
STARTS TO SHIFT EAST OF THE AREA. HOWEVER...IT STILL LOOKS TO
REMAIN CLOUDY THROUGH THE OVERNIGHT HOURS...WITH MIN TEMPS MAINLY
IN THE UPPER 50S TO MID 60S.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
TOMORROW...THE UPPER LEVEL LOW WILL START TO SHIFT OFFSHORE.
HOWEVER...CYCLONIC FLOW AROUND THIS SYSTEM WILL CONTINUE TO ALLOW
FOR THE THREAT FOR SOME SCATTERED SHOWERS...ESP DURING DAYTIME
HEATING. ANY RAINFALL WILL BE MUCH LIGHTER ON FRIDAY...AS THE BEST
MOISTURE WILL BE STARTING TO SHIFT SOUTH AND EAST TOWARDS
SOUTHERN NEW ENGLAND. IT STILL LOOKS TO STAY FAIRLY CLOUDY WITH
THE UPPER LOW NEARBY...SO TEMPS WILL BE HELD DOWN. MAX TEMPS WILL
ONLY BE IN THE UPPER 60S TO MID 70S.
THE UPPER LEVEL LOW WILL CONTINUE TO MOVE AWAY FROM THE REGION
BETWEEN FRIDAY NIGHT AND SATURDAY. A LINGERING SPRINKLE OR SHOWER
CANNOT TOTALLY BE RULED OUT OVER THE HIGH TERRAIN...OTHERWISE IT
LOOKS TO BE DRY. FINALLY...SOME BREAKS IN THE CLOUDS WILL START TO
OCCUR...ESP BY SAT MORNING FROM NORTH TO SOUTH...AS DRIER AIR
STARTS TO WORK IN FROM SOUTHERN CANADA. MIN TEMPS FRI NIGHT WILL
BE IN THE 50S...WITH HIGHS ON SATURDAY IN THE 70S.
UPPER LEVEL RIDGING WILL START TO BUILD INTO THE AREA FOR SATURDAY
NIGHT FROM THE GREAT LAKES AND OHIO VALLEY. WITH CLEARING SKIES
AND LIGHT WINDS...GOOD RADIATIONAL COOLING CAN BE
EXPECTED...ALLOWING FOR TEMPS TO FALL EASILY. OVERNIGHT LOWS WILL
RANGE FROM THE UPPER 40S OVER THE ADIRONDACKS TO THE MID 50S IN
THE CAPITAL REGION AND MID HUDSON VALLEY.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE DOMINATES THE WEATHER OVER THE REGION SUNDAY THROUGH
WEDNESDAY WITH GRADUAL WARMING EACH DAY AS THE HIGH PRESSURE BUILDS
OFFSHORE. HIGHS SUNDAY AND MONDAY IN THE MID 70S TO LOWER 80S. HIGHS
TUESDAY AND WEDNESDAY IN THE LOWER TO MID 80S...WITH UPPER 70S TO
LOWER 80S IN HIGHER TERRAIN.
A WEAK COLD FRONT JUST BEGINS TO APPROACH WEDNESDAY NIGHT AND
THURSDAY BUT THE LOW LEVEL THERMAL RIDGING SHOULD STILL BE IN PLACE.
SO...JUST SOME ISOLATED SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT
AND THURSDAY WITH HIGHS THURSDAY IN THE 80S.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
A MIXTURE OF VFR/MVFR FLYING CONDITIONS ARE GENERALLY EXPECTED AT
THE TAF SITES THIS AFTERNOON BEFORE LOWERING TO MVFR/IFR TONIGHT.
THIS AFTERNOON...AN AREA OF LOW PRESSURE AND ITS ASSOCIATED FRONTAL
BOUNDARY WILL CONTINUE TO SLOWLY PUSH ACROSS THE REGION THIS
AFTERNOON...WITH A MIXTURE OF VFR/MVFR CEILINGS AND VISIBILITIES
EXPECTED. PERIODS OF SHOWERS AND A FEW ISOLATED THUNDERSTORMS WILL
BE POSSIBLE...WITH TEMPO GROUPS INDICATING PERIODS OF PRIMARILY MVFR
AT THE TAF SITES ASSOCIATED WITH THE SHOWERS/STORMS WITH EVEN SOME
IFR CEILINGS POSSIBLE AT KGFL AND KPSF. THE GREATEST THREAT FOR
SHOWERS/STORMS APPEARS TO BE BETWEEN 20Z AND 02Z THIS
AFTERNOON/EARLY EVENING. WINDS WILL BE LIGHT AND VARIABLE GENERALLY
LESS THAN 5 KNOTS.
TONIGHT INTO FRIDAY...AS THE LOW PRESSURE SYSTEM CONTINUES TO SLOWLY
MOVE ACROSS THE AREA...SHOWERS WILL CONTINUE TO LINGER INTO THE
OVERNIGHT HOURS AS FLYING CONDITIONS FALL TO MVFR/IFR. AT THIS TIME
THE GREATEST LIKELIHOOD FOR IFR IS AT KGFL AND KPSF...ALTHOUGH
CANNOT RULE OUT A PERIOD OF IFR STRATUS AT KALB AND KPOU AFTER 06Z
AS WELL. SHOWER ACTIVITY IS EXPECTED TO WANE AFTER 06Z AT KGFL AND
KALB...BUT CONTINUE TO LINGER THROUGH THE REMAINDER OF THE NIGHT AT
KPOU AND KPSF. KEPT IFR STRATUS OUT OF KALB AND KPOU FOR THIS TAF
ISSUANCE AS CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN TAFS. MVFR
CEILINGS ARE EXPECTED TO LINGER THROUGH THE REMAINDER OF THE TAF
PERIOD AFTER 12Z FRIDAY WITH A GRADUALLY DECREASING CHANCE FOR
SHOWERS AS DRIER AIR BEGINS TO BUILD INTO THE REGION.
WINDS TONIGHT WILL TREND TOWARDS CALM BEFORE BECOMING LIGHT AND
VARIABLE FRIDAY AROUND 5 KNOTS.
OUTLOOK...
FRIDAY NIGHT: LOW OPERATIONAL IMPACT. NO SIG WX.
SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SATURDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT WILL
KEEP FIRE WEATHER CONCERNS AT A MINIMUM. RH VALUES WILL BE NEAR
100 PERCENT IN MOST LOCATIONS TONIGHT. WITH CLOUDS AND SCATTERED SHOWERS
AROUND TOMORROW...RH VALUES WILL REMAIN ABOVE 70 PERCENT THROUGH
THE ENTIRE DAY...WITH LIGHT AND VARIABLE WINDS.
&&
.HYDROLOGY...
SHOWERS AND THUNDERSTORMS ARE CURRENTLY MOVING ACROSS THE REGION
THANKS TO A SLOW MOVING UPPER LEVEL LOW. THESE SHOWERS AND
THUNDERSTORMS ARE RATHER SLOW MOVING...AND WITH PWATS ABOVE NORMAL
/1.63 INCHES ON THIS MORNINGS 12Z KALY SOUNDING/...THERE IS THE
POTENTIAL FOR HEAVY RAIN IN A SHORT PERIOD OF TIME.
SOME AREAS...GENERALLY FROM AROUND AMSTERDAM NORTHEAST ACROSS THE
SACANDAGA LAKE AND INTO WESTERN SARATOGA COUNTY...SAW TWO TO FOUR
INCHES OF RAIN LAST NIGHT. ELSEWHERE...GROUND CONDITIONS HAVE BEEN
RATHER DRY...DUE TO A LACK OF RECENT RAINFALL. AS A RESULT...MOST
AREAS WILL BE ABLE TO HANDLE SOME RAINFALL. HOWEVER...IF HEAVY
RAIN OCCURS OVER THOSE AREAS THAT SAW RAINFALL LAST NIGHT OR IF
RAINFALL REPEATEDLY MOVES OVER THE SAME LOCATION THIS AFTN INTO
EVENING...THEN SOME MINOR FLOODING OF URBAN...POOR DRAINAGE AND
LOW LYING AREAS MAY OCCUR. AN ISOLATED FLASH FLOOD CANNOT TOTALLY
BE RULED OUT...ALTHOUGH ANY POSSIBLE FLOOD ISSUES WOULD LIKELY BE
MORE OF THE POOR DRAINAGE/URBAN TYPE CONCERNS.
THE THREAT FOR HEAVY RAINFALL WILL END TONIGHT...AS THE BEST
FORCING STARTS TO SHIFT AWAY FROM THE AREA. EVEN THOUGH THERE MAY
SOME LINGERING RAIN SHOWERS INTO TOMORROW...NO ADDITIONAL HEAVY
RAINFALL IS EXPECTED.
WHILE THERE MAY BE SOME RISES ON MAIN STREAM RIVERS DUE TO THE
RAINFALL...NO FLOODING OF LARGER RIVERS IS EXPECTED. WITH DRY
WEATHER RETURNING FOR SUNDAY INTO NEXT WEEK...RIVER LEVELS WILL
RECEDE AND/OR HOLD STEADY INTO NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...IRL
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS ALBANY NY
135 PM EDT THU AUG 21 2014
.SYNOPSIS...
A SLOW MOVING UPPER LEVEL LOW OVER THE GREAT LAKES REGION WILL
IMPACT THE FORECAST AREA WITH SHOWERS AND THUNDERSTORM AS IT DRIFTS
EASTWARD THROUGH TONIGHT. THE UPPER LEVEL LOW WILL TRACK OFF THE
COAST TOMORROW WITH A FEW LINGERING SHOWERS AND COOL TEMPERATURES
OVER THE AREA. IMPROVING CONDITIONS ARE EXPECTED OVER THE
WEEKEND...WITH INCREASING AMOUNTS OF MORE SUNSHINE AND WARMER
TEMPERATURES INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 135 PM EDT...LATEST REGIONAL MOSAIC RADAR SHOWS AREAS OF
MAINLY SCATTERED SHOWERS AND THUNDERSTORMS OVER THE
REGION. THE BIGGEST CONCENTRATION IS WEST OF THE AREA TOWARDS
CENTRAL NY...THE FINGER LAKES...AND THE SOUTHERN TIER. OVER THE
NEXT FEW HOURS...THIS ACTIVITY WILL SPREAD ACROSS EASTERN NY AND
EVENTUALLY WESTERN NEW ENGLAND FROM THE WEST TO EAST...AS SHOWN IN
THE LATEST 3KM HRRR GUIDANCE. ANY THUNDERSTORMS MAY CONTAIN A
BRIEF PERIOD OF HEAVY RAINFALL...AND IF THIS OCCURS OVER ANY AREAS
THAT SAW SIGNIFICANT RAIN LAST NIGHT /SUCH AS THE SACANDAGA
AREA/...THEN THERE MAY BE SOME MINOR FLOODING...ESP OF LOW LYING
AND URBAN AREAS. OTHERWISE...OUTSIDE THE ON AND OFF
SHOWERS/THUNDERSTORMS...IT WILL REMAIN FAIRLY CLOUDY OVER THE
AREA THIS AFTERNOON WITH JUST A FEW BREAKS OR LIGHTENING UP OF THE
SKIES...ALONG WITH CONTINUED MUGGY CONDITIONS.
TEMPS ARE ALREADY CLOSE TO THEIR HIGHS FOR THE DAY AND WILL EITHER
HOLD STEADY OR ONLY RISE A DEGREE OR TWO MORE. HIGHS ARE GENERALLY
EXPECTED TO BE IN THE 70S...WITH UPPER 60S OVER THE HIGH TERRAIN
OF NEW ENGLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
THE SYSTEM WILL MOVE OFF THE COAST TONIGHT AND EARLY FRIDAY...WITH
DRIER AIR WORKING SOUTHWESTWARD INTO THE REGION FROM A SPRAWLING
HIGH PRESSURE SYSTEM OVER THE CANADIAN MARITIMES. POPS ARE SLOWLY
FORECAST TO DECREASE TONIGHT AND FRIDAY...WITH MAINLY JUST SLIGHT
CHANCE POPS ACROSS THE REGION BY FRIDAY AFTERNOON. AS THE DRIER AIR
CONTINUES TO PUSH INTO THE REGION AND HIGH PRESSURE AT ALL LEVELS OF
THE ATMOSPHERE BEGINS TO BUILD INTO THE REGION...CLOUDS WILL SLOWLY
DECREASE LATE FRIDAY THROUGH FRIDAY NIGHT...WITH PARTLY SUNNY SKIES
ON SATURDAY.
LOWS TONIGHT WILL BE IN THE MID 50S TO LOWER 60S. HIGHS FRIDAY MID
60S TO LOWER 70S. LOWS FRIDAY NIGHT IN THE 50S. HIGHS SATURDAY IN
THE 70S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A NICE STRETCH OF WEATHER IS EXPECTED IN THE LONG TERM FROM THE
WEEKEND INTO THE MIDDLE OF NEXT WEEK WITH TEMPS RISING TO SLIGHTLY
ABOVE NORMAL LEVELS AS WE ENTER THE LAST WEEK OF AUGUST.
WPC GUIDANCE/ECMWF/ENSEMBLES/GFS ARE IN PRETTY GOOD AGREEMENT HIGH
PRESSURE WILL BUILD IN OVER NY AND NEW ENGLAND FROM SRN QUEBEC AND
NRN NEW ENGLAND SAT NIGHT...AND BE CENTERED OVER THE NORTHEAST
SUNDAY TO TUESDAY...AS A MID AND UPPER LEVEL RIDGE BUILDS IN FROM
THE MS RIVER VALLEY AND PLAINS. AN UPPER LEVEL TROUGH SETS UP DOWN
STREAM OVER THE CANADIAN MARITIMES...AND LARGE-SCALE SYNOPTIC
SUBSIDENCE WILL INFLUENCE THE WEATHER OVER THE LONG TERM STRETCH.
A WEAK COLD FRONTAL BOUNDARY WITH LIMITED LOW-LEVEL MOISTURE TO WORK
WITH MAY MOVE ACROSS THE REGION WEDNESDAY AFTERNOON INTO THURSDAY.
ONLY A SLIGHT CHC OF SHOWERS WAS ADDED TO THE GRIDDED FORECASTS WED
PM INTO WED NIGHT NW OF THE CAPITAL REGION.
TEMPS WILL START OUT COOLER THAN NORMAL FOR THE CLOSE OF THE WEEKEND
WITH 50S FOR LOWS...AND HIGHS IN THE LOWER TO M70S IN THE
VALLEYS...AND M60S TO L70S OVER THE HILLS AND MTNS.
MONDAY INTO TUESDAY...H850 TEMP MODERATE TO +13C TO +14C WITH DECENT
MIXING...AS SFC HIGH PRESSURE DRIFTS SLIGHTLY SOUTH AND WEST OF
UPSTATE NY AND NEW ENGLAND. EXPECT HIGHS TO REACH THE U70S TO L80S
IN THE VALLEY AREAS...AND LOWER TO M70S OVER THE MTNS. LOWS WILL BE
IN THE 50S TO L60S. WEDNESDAY LOOKS LIKE THE WARMEST AFTERNOON WITH
M70S TO L80S FOR HIGHS...AND HUMIDITY LEVELS CREEPING UP WITH SFC
DEWPTS IN THE M50S TO L60S.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
A MIXTURE OF VFR/MVFR FLYING CONDITIONS ARE GENERALLY EXPECTED AT
THE TAF SITES THIS AFTERNOON BEFORE LOWERING TO MVFR/IFR TONIGHT.
THIS AFTERNOON...AN AREA OF LOW PRESSURE AND ITS ASSOCIATED FRONTAL
BOUNDARY WILL CONTINUE TO SLOWLY PUSH ACROSS THE REGION THIS
AFTERNOON...WITH A MIXTURE OF VFR/MVFR CEILINGS AND VISIBILITIES
EXPECTED. PERIODS OF SHOWERS AND A FEW ISOLATED THUNDERSTORMS WILL
BE POSSIBLE...WITH TEMPO GROUPS INDICATING PERIODS OF PRIMARILY MVFR
AT THE TAF SITES ASSOCIATED WITH THE SHOWERS/STORMS WITH EVEN SOME
IFR CEILINGS POSSIBLE AT KGFL AND KPSF. THE GREATEST THREAT FOR
SHOWERS/STORMS APPEARS TO BE BETWEEN 20Z AND 02Z THIS
AFTERNOON/EARLY EVENING. WINDS WILL BE LIGHT AND VARIABLE GENERALLY
LESS THAN 5 KNOTS.
TONIGHT INTO FRIDAY...AS THE LOW PRESSURE SYSTEM CONTINUES TO SLOWLY
MOVE ACROSS THE AREA...SHOWERS WILL CONTINUE TO LINGER INTO THE
OVERNIGHT HOURS AS FLYING CONDITIONS FALL TO MVFR/IFR. AT THIS TIME
THE GREATEST LIKELIHOOD FOR IFR IS AT KGFL AND KPSF...ALTHOUGH
CANNOT RULE OUT A PERIOD OF IFR STRATUS AT KALB AND KPOU AFTER 06Z
AS WELL. SHOWER ACTIVITY IS EXPECTED TO WANE AFTER 06Z AT KGFL AND
KALB...BUT CONTINUE TO LINGER THROUGH THE REMAINDER OF THE NIGHT AT
KPOU AND KPSF. KEPT IFR STRATUS OUT OF KALB AND KPOU FOR THIS TAF
ISSUANCE AS CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN TAFS. MVFR
CEILINGS ARE EXPECTED TO LINGER THROUGH THE REMAINDER OF THE TAF
PERIOD AFTER 12Z FRIDAY WITH A GRADUALLY DECREASING CHANCE FOR
SHOWERS AS DRIER AIR BEGINS TO BUILD INTO THE REGION.
WINDS TONIGHT WILL TREND TOWARDS CALM BEFORE BECOMING LIGHT AND
VARIABLE FRIDAY AROUND 5 KNOTS.
OUTLOOK...
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
FRIDAY NIGHT-MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
SCATTERED TO NUMEROUS SHOWERS WILL PERSIST THROUGH TONIGHT. IT WILL
REMAIN MOSTLY CLOUDY AND DAMP FOR FRIDAY WITH A FEW LINGERING
SHOWERS POSSIBLE.
RH VALUES WILL BE ELEVATED THE NEXT COUPLE OF DAYS...GENERALLY OVER
60 PERCENT...SOMETIMES CLOSE TO 100 PERCENT...DUE TO THE WET WEATHER
AND CLOUDY CONDITIONS.
THE WIND WILL VARIABLE TO SOUTHEASTERLY AT 5-10 MPH TODAY THROUGH
FRIDAY.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS AT THIS TIME.
A SLOW MOVING WEAK LOW PRESSURE SYSTEM OVER THE GREAT LAKES REGION
WILL IMPACT THE FORECAST AREA WITH SHOWERS AND POSSIBLY A STRAY
THUNDERSTORM AS IT DRIFTS EASTWARD OVERNIGHT INTO THURSDAY NIGHT.
THE LOW WILL TRACK OFF THE COAST FRIDAY.
AS OF 400 AM...RADAR INDICATES THAT LOCALIZED AMOUNTS OF UP TO THREE
INCHES OF RAIN HAD FALLEN SINCE WEDNESDAY FROM THE MOHAWK VALLEY
INTO THE SARATOGA REGION. GENERALLY A THIRD OF AN INCH TO ONE AND A
HALF INCHES OF RAIN HAD FALLEN ACROSS THE NORTHWEST THIRD OF THE
FORECAST AREA...WITH MUCH LOWER AMOUNTS ELSEWHERE.
THIS SYSTEM WILL CONTINUE TO PRODUCE AREAS OF SHOWERS THROUGH
TONIGHT...WITH ADDITIONAL RAINFALL AMOUNTS OF A HALF TO ONE INCH IN
MANY AREAS...BUT LOCALIZED AMOUNTS OF ANOTHER TWO TO THREE INCHES
ARE POSSIBLE.
DUE TO LOW RIVER LEVELS AND FAIRLY DRY SOIL CONDITIONS BEFORE THE
RAIN BEGAN...THE IMPACT ON AREA STREAMS AND RIVERS WILL GENERALLY BE
MINOR AND NO RIVER FLOODING IS EXPECTED. BE.
HOWEVER...ANY SHOWER OR THUNDERSTORM COULD PRODUCE LOCALIZED HEAVY
RAINFALL AMOUNTS...WHICH COULD RESULT IN SIGNIFICANT PONDING OF
WATER ON ROADWAYS AND MINOR FLOODING IN AREAS OF POOR DRAINAGE.
THERE COULD BE SOME ADDITIONAL SHOWERS ON FRIDAY BUT THESE SHOULD BE
LIGHT.
DRY WEATHER RETURNS BY THE WEEKEND AND FOR MUCH OF NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...GJM
LONG TERM...WASULA
AVIATION...IRL
FIRE WEATHER...GJM
HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
535 PM EDT THU AUG 21 2014
.SYNOPSIS...
A BUILDING UPPER RIDGE WILL LEAD TO CONTINUED HOT CONDITIONS
FRIDAY. A BACK DOOR COLD FRONT WILL MOVE SW INTO THE NORTHERN AND
CENTRAL MIDLANDS SATURDAY AFTERNOON...AND SHIFT TOWARDS THE CSRA
SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND
AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL
LEVELS BEHIND IT. THE FRONT WILL SHIFT TO OUR SOUTH EARLY TO MID
NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL
TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
UPPER RIDGE AND SURFACE HIGH PRESSURE CENTERED OVER THE LOWER
MISSISSIPPI VALLEY/GULF COAST BUILDING INTO THE REGION. LATE
AFTERNOON VISIBLE SATELLITE CONTINUES TO INDICATE SUBSIDENCE
ACROSS THE AREA WITH VERY FEW CLOUDS.
WEAK INSTABILITY AND WARM TEMPERATURES ALOFT. LFC REMAINS
HIGH...CONVECTIVE TEMPS HIGH AND TRIGGER LACKING. CURRENT RAP AND
NAM MODEL STILL INDICATING A WEAKENING SHORT WAVE CROSS THE AREA
AFTER 22Z. 88D REGIONAL COMPOSITE SHOWS A FEW
SHOWERS/THUNDERSTORMS ACROSS THE UPSTATE AND GEORGIA...BUT THE
MIDLANDS AND CSRA REMAIN PRECIP FREE. HOWEVER WITH S/W...AN ISOLATED
EARLY EVENING THUNDERSTORM IS STILL POSSIBLE WITH HE BEST CHANCES
ALONG AND WEST OF THE SAVANNAH RIVER INTO CENTRAL GEORGIA. HAVE
KEPT POPS LESS THAN 15 PERCENT WITH NO MENTION IN THE FORECAST.
EXPECT SOME DEBRIS CLOUDS TONIGHT FROM UPSTREAM CONVECTION.
OVERNIGHT LOWS IN THE LOW TO MID 70S ARE FORECAST.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
LITTLE CHANGE FRIDAY. UPPER RIDGE WILL REMAIN CENTERED JUST TO OUR
WEST...WITH SURFACE TROUGH ACROSS THE COASTAL CAROLINAS. THIS AND
A LOW LEVEL DOWNSLOPE FLOW WILL LEAD TO CONTINUED HOT MAX TEMPS.
MODELS CONTINUE TO INDICATE MAX TEMPS NEAR 100 DEGREES AGAIN MOST
AREAS...AND ALSO CONTINUES TO INDICATES DEW POINTS MIXING DOWN
INTO THE 60S ACROSS MOST OF OUR FA TO NEAR 70 SE FA...KEEPING HEAT
INDICES BELOW OUR HEAT ADVISORY CRITERIA OF 110F. ONLY ISOLATED TO
SLIGHT CHANCE DIRUNAL TSTMS AT BEST DUE TO BUILDING RIDGE
ALOFT...AND FAIRLY DRY LOW LEVEL AIR LEADING TO HIGH LEVELS OF
FREE CONVECTION/HIGH CONVECTIVE TEMPS.
MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING
BACK DOOR FRONT. LATEST NAM A LITTLE FASTER THAN GFS. GUIDANCE
BLEND AND SHORT RANGE ENSEMBLE SUGGEST FRONT WITH ASSOCIATED BAND
OF THUNDERSTORMS MOVING INTO THE NORTHERN AND CENTRAL FA SATURDAY
AFTERNOON. CHANCE POPS SHOULD GENERALLY SUFFICE.
WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH
WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN.
WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE
NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX
TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100
REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH
TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY
CRITERIA OF 110F.
FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NT THRU SUN NT. EXPECT
CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS
ALONG AND NORTH OF IT. SO...POPS SUN AFTN FAVORING THE CSRA. HIGH
TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
FRONT TO PUSH TO OUR SOUTH EARLY TO MID NEXT WEEK WITH SURFACE HIGH
PRESSURE BUILDING DOWN THE EASTERN SEABOARD...WITH UPPER RIDGE
ALOFT. SLIGHTLY COOLER AND DRIER AIR BEHIND THE FRONT ALONG WITH
RIDGE ALOFT WILL REDUCE CONVECTIVE CHANCES...TO SLIGHT CHANCE AT
BEST. TEMPS EXPECTED TO BE GENERALLY NEAR NORMAL.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS EXPECTED TO DOMINATE THE PERIOD.
EXPECT A FEW DIURNAL CUMULUS THIS AFTERNOON...BUT SKIES WILL
REMAIN NEARLY SUNNY. POTENTIAL FOR CONVECTION REMAINS TOO LOW TO
INCLUDE IN TAFS. CUMULUS WILL DISSIPATE WITH SUNSET WITH
CONVECTIVE DEBRIS CROSSING THE AREA TONIGHT...WHICH WILL AGAIN
WORK TO PREVENT FOG DEVELOPMENT. GFS LAMP STILL INDICATING MVFR
FOG AT AGS/OGB 06Z- 13Z. GIVEN EXPECTED DRY AIRMASS AND HIGH
CLOUDS...WILL NOT INCLUDE IN FOG IN THE FORECAST. NORTHERLY WINDS
AROUND 5 KNOTS THIS AFTERNOON DIMINISHING TO NEAR CALM TONIGHT.
EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE
NIGHT AND EARLY MORNING FOG SATURDAY THROUGH MONDAY. ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
77
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
214 PM EDT THU AUG 21 2014
.SYNOPSIS...
A BUILDING UPPER RIDGE WILL LEAD TO CONTINUED HOT CONDITIONS
FRIDAY. A BACK DOOR COLD FRONT WILL MOVE SW INTO THE NORTHERN AND
CENTRAL MIDLANDS SATURDAY AFTERNOON...AND SHIFT TOWARDS THE CSRA
SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND
AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL
LEVELS BEHIND IT. THE FRONT WILL SHIFT TO OUR SOUTH EARLY TO MID
NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL
TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPPER RIDGE AND SURFACE HIGH PRESSURE CENTERED OVER THE LOWER
MISSISSIPPI VALLEY/GULF COAST BUILDING INTO THE REGION. VISIBLE
SATELLITE INDICATING SUBSIDENCE ACROSS THE AREA WITH PRACTICALLY NO
CLOUDS. 850MB WARM ADVECTION/DOWNSLOPE FLOW WILL RESULT IN
TEMPERATURES APPROACHING 100 DEGREES.
WEAK INSTABILITY AND WARM TEMPERATURES ALOFT. LFC REMAINS
HIGH...CONVECTIVE TEMPS HIGH AND TRIGGER LACKING. CURRENT RAP AND
NAM MODEL STILL INDICATING A WEAKENING SHORT WAVE CROSS THE AREA
AFTER 22Z. SO CANNOT RULE OUT ISOLATED LATE AFTERNOON/EARLY EVENING
THUNDERSTORM. HAVE LOWERED POPS TO LESS THAN 15 PERCENT.
DEW POINTS MIXING OUT INTO THE LOW/MID 60S THIS AFTERNOON SO HEAT
INDEX LIKELY MAXING OUT AROUND 102 DEGREES.
EXPECT DEBRIS CLOUDS TONIGHT FROM UPSTREAM CONVECTION. OVERNIGHT
LOWS IN THE LOW TO MID 70S ARE FORECAST.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
LITTLE CHANGE FRIDAY. UPPER RIDGE WILL REMAIN CENTERED JUST TO OUR
WEST...WITH SURFACE TROUGH ACROSS THE COASTAL CAROLINAS. THIS AND
A LOW LEVEL DOWNSLOPE FLOW WILL LEAD TO CONTINUED HOT MAX TEMPS.
MODELS CONTINUE TO INDICATE MAX TEMPS NEAR 100 DEGREES AGAIN MOST
AREAS...AND ALSO CONTINUES TO INDICATES DEW POINTS MIXING DOWN
INTO THE 60S ACROSS MOST OF OUR FA TO NEAR 70 SE FA...KEEPING HEAT
INDICES BELOW OUR HEAT ADVISORY CRITERIA OF 110F. ONLY ISOLATED TO
SLIGHT CHANCE DIRUNAL TSTMS AT BEST DUE TO BUILDING RIDGE
ALOFT...AND FAIRLY DRY LOW LEVEL AIR LEADING TO HIGH LEVELS OF
FREE CONVECTION/HIGH CONVECTIVE TEMPS.
MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING
BACK DOOR FRONT. LATEST NAM A LITTLE FASTER THAN GFS. GUIDANCE
BLEND AND SHORT RANGE ENSEMBLE SUGGEST FRONT WITH ASSOCIATED BAND
OF THUNDERSTORMS MOVING INTO THE NORTHERN AND CENTRAL FA SATURDAY
AFTERNOON. CHANCE POPS SHOULD GENERALLY SUFFICE.
WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH
WARMEST TEMPS FAVOIRNG THE CSRA WHERE TEMPS COULD REACH 100 AGAIN.
WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE
NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX
TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100
REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH
TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVIOSRY
CRITERIA OF 110F.
FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NT THRU SUN NT. EXPECT
CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS
ALONG AND NORTH OF IT. SO...POPS SUN AFTN FAVORING THE CSRA. HIGH
TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
FRONT TO PUSH TO OUR SOUTH EARLY TO MID NEXT WEEK WITH SURFACE HIGH
PRESSURE BUILDING DOWN THE EASTERN SEABOARD...WITH UPPER RIDGE
ALOFT. SLIGHTLY COOLER AND DRIER AIR BEHIND THE FRONT ALONG WITH
RIDGE ALOFT WILL REDUCE CONVECTIVE CHANCES...TO SLIGHT CHANCE AT
BEST. TEMPS EXPECTED TO BE GENERALLY NEAR NORMAL.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS EXPECTED TO DOMINATE THE PERIOD.
EXPECT SOME DIURNAL CUMULUS TO DEVELOP THIS AFTERNOON.
POTENTIAL FOR CONVECTION REMAINS TOO LOW TO INCLUDE IN TAFS.
CUMULUS WILL DISSIPATE WITH SUNSET WITH CONVECTIVE DEBRIS CROSSING
THE AREA TONIGHT...WHICH WILL AGAIN WORK TO PREVENT FOG DEVELOPMENT.
GFS LAMP STILL INDICATING MVFR FOG AT AGS/OGB 06Z-13Z. GIVEN
EXPECTED DRY AIRMASS AND HIGH CLOUDS...WILL NOT INCLUDE IN FOG IN THE
FORECAST. NORTHERLY WINDS AROUND 5 KNOTS THIS AFTERNOON DIMINISHING
TO NEAR CALM TONIGHT.
EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE
NIGHT AND EARLY MORNING FOG SATURDAY THROUGH MONDAY. ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
300 PM CDT THU AUG 21 2014
.DISCUSSION...
300 PM CDT
SHORT TERM DISCUSSION TO BE ISSUED SHORTLY.
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
THE MID SUMMER PATTERN WILL CONTINUE THROUGH AT LEAST WEDNESDAY NEXT
WEEK BEFORE A STRONG UPPER TROUGH DIGS INTO THE GREAT LAKES REGION
AND PUTS AN END TO THE EXTENDED STRETCH OF HEAT AND HUMIDITY.
SUNDAY THROUGH TUESDAY...
ENSEMBLES ARE EXHIBITING HIGH CONFIDENCE
IN A 590+ DAM H5 RIDGE CENTERED OVER THE LOWER AND MID MS VALLEY
SUNDAY NIGHT BEFORE BEING FLATTENED/SHUNTED EAST MONDAY INTO TUESDAY
BY DISTURBANCES EMANATING FROM UPPER TROUGH FROM THE CANADIAN
PRAIRIES TO THE NORTHERN ROCKIES. 850/925 MB CLIMO ON MONDAY-TUESDAY
SUPPORTS HIGHS OF AT LEAST AROUND 90/LOW 90S...BUT MAIN UNCERTAINTY
IS EXTENT OF CONVECTIVE ACTIVITY. SYNOPTIC SET-UP WITH FLATTENING
RIDGE FAVORS MAINTAINING LOW TO MID CHANCE POPS ON MON-TUE AS SW
FLOW DISTURBANCES COULD KICK OFF SHRA/TSRA IN PRESENCE OF MINIMAL
CAPPING PER SOUNDINGS AND CONTINUED LOW-MID 70S DEW POINTS. ANY TSRA
COULD PRODUCE HEAVY DOWNPOURS GIVEN PROGGED PWAT VALUES IN 1.5 TO
1.75 INCH RANGE.
AT THIS TIME...IT WOULD APPEAR THAT MONDAY HAS A BETTER CHANCE TO
HAVE LESS IN THE WAY OF CONVECTION AND CLOUDS. IF THIS
OCCURS...FORECAST HIGH TEMPS COULD EVEN BE A BIT CONSERVATIVE...WITH
GUIDANCE INDICATING 850 MB TEMPS IN THE LOW 20SC AND 925 MB TEMPS IN
THE MID 20SC. BOTH DAYS COULD HAVE SOME LAKE COOLING GIVEN FAIRLY
WEAK GRADIENT AND FLOW ALOFT. IF CLOUDS/CONVECTION DO NOT LIMIT
WARMING POTENTIAL TOO MUCH...THEN BOTH DAYS ARE LIKELY TO HAVE HEAT
INDEX VALUES APPROACHING OR EXCEEDING 100 DEGREES FOR AT LEAST
PORTIONS OF THE CWA.
TUESDAY NIGHT THROUGH THURSDAY...
SPREAD INCREASES ON THE ENSEMBLES AND OPERATIONAL MODELS WITH
RESPECT TO SPEED AT WHICH DEEP UPPER TROUGH AND ASSOCIATED SURFACE
LOW DIG INTO GREAT LAKES REGION. HAVE CONCERN IN THIS PERIOD EVEN
THIS FAR OUT FOR HEAVY RAIN/FLOODING POTENTIAL...AS POSITION OF CWA
BETWEEN DEEP UPSTREAM TROUGH AND STRONG DOWNSTREAM RIDGE IS A
SYNOPTICALLY FAVORABLE SET-UP FOR STRONG LLJ/MOISTURE TRANSPORT.
PWAT VALUES COULD NEAR 2 INCHES. INCREASED FLOW ALOFT WILL ALSO
RESULT IN INCREASED DEEP LAYER SHEAR SUPPORTIVE OF STRONG/SEVERE
STORMS PENDING MESOSCALE COMING TOGETHER. 12Z ECMWF IS ACTUALLY ON
FASTER END OF SPECTRUM COMPARED TO GFS AND ENSEMBLE MEAN WITH
PROGRESSION OF SYSTEM...SO GENERALLY MAINTAINED CHANCE POPS FROM
BLENDED GUIDANCE DUE TO UNCERTAINTY. TEMPERATURES WEDNESDAY WILL BE
DICTATED BY TIMING...AS UPSTREAM AIR MASS IS MUCH
COOLER...ESPECIALLY ON LATEST ECMWF. THURSDAY TEMPS COULD RANGE FROM
NEAR TO SLIGHTLY BELOW SEASONABLE TO WELL BELOW NORMAL...BUT DID NOT
STRAY AWAY FROM SMART BLEND.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH A CHANCE
LATE THIS AFTERNOON...AND AGAIN OVERNIGHT.
* LOWER CEILINGS OR VISIBILITY FRIDAY MORNING
* POTENTIAL EAST WINDS FRIDAY AFTERNOON BUT GENERALLY UNDER 10 KT
KMD
//DISCUSSION...UPDATED 18Z...
THUNDER HAS REMAINED WEST AND NORTH WITH THE CURRENT BAND OF
SHOWER ACTIVITY THAT WILL PUSH THROUGH NORTHEAST ILLINOIS IN THE
NEXT FEW HOURS. THERE IS ANOTHER AREA OF THUNDERSTORMS THAT
CONTINUES TO ORGANIZE IN EASTERN IOWA THAT WILL GET AN ADDITIONAL
SHOVE EASTWARD LATER THIS AFTERNOON AS A SHORT WAVE IN WESTERN
CENTRAL IOWA SPREADS INTO ILLINOIS AND THEN SOUTHEASTWARD INTO
INDIANA THIS EVENING. THIS MAY BRING A PERIOD OF SHOWERS OR
THUNDERSTORMS TO THE TERMINALS DURING THE LATE AFTERNOON INTO THE
EARLY EVENING PERIOD. HAVE GONE WITH SHOWERS FOR NOW GIVEN RECENT
TRENDS BUT THIS MAY BE A PERIOD DURING THE AFTERNOON-EARLY EVENING
RUSH WHERE THERE MAY BE THUNDER IN THE VICINITY AND IS A PERIOD WE
WILL MONITOR IN THE COMING HOURS.
THEN THERE APPEARS TO BE A BREAK IN THE EVENING TIME FRAME AS
UPPER LEVEL FORCING DIMINISHES. WARM AIR ADVECTION THEN RAMPS BACK
UP IN WEST CENTRAL IOWA. IF THIS ACTIVITY GETS MOVING INTO
ILLINOIS IT LOOKS TO COME THROUGH OVERNIGHT. THEREFORE PUSHED THE
GOING PROB30 BACK TO ACCOUNT FOR THIS TIME FRAME.
THERE MAY ALSO BE SOME LOWER CLOUDS OR REDUCED VISIBILITIES LATE
TONIGHT INTO EARLY FRIDAY AFTER ADDITIONAL CONVECTIVE ACTIVITY
WINDS DOWN AND WINDS SLACKEN.
KMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-HIGH IN PERIODS OF SHOWERS THIS AFTERNOON...HIGH IN NO
THUNDER FOR THE NEXT FEW HOURS. LOW IN THUNDER CHANCES LATER
THIS AFTERNOON. LOW- MEDIUM IN THUNDER CHANCES TONIGHT AND LOW
IN TIMING.
* LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION
EXCEPT AROUND SHOWERS.
* LOW IN WIND DIRECTION FRIDAY AFTERNOON
KMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
* FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA
WITH OCNL MVFR CIGS/VIS.
KREIN
&&
.MARINE...
205 PM CDT
THE WEATHER PATTERN WILL NOT CHANGE MUCH OVER LAKE MICHIGAN
THROUGH THIS WEEKEND WITH LOW PRESSURE ACROSS THE CENTRAL PLAINS AND
HIGH PRESSURE OVER ONTARIO. A FRONT EXTENDING EAST FROM THE LOW IS
PRESENTLY DRAPED ACROSS THE FAR SOUTHERN PART OF THE LAKE AND THIS
WILL MOVE LITTLE THROUGH EARLY FRIDAY BEFORE SHIFTING BACK
SOUTH OF THE LAKE ON FRIDAY NIGHT. SOME THUNDERSTORMS ACROSS THE
SOUTHERN PART OF THE LAKE LATE THIS AFTERNOON MAY CAUSE SOME
VARIABILITY AND SLIGHTLY ENHANCED GUSTS IN THE WINDS...BUT ANY OF
THIS SHOULD BE TEMPORARY. THE WINDS WILL THEN TURN SOUTHERLY
ACROSS THE ENTIRE LAKE BY SUNDAY WITH THE LOW PRESSURE LIFTING
NORTH INTO SOUTHERN CANADA BY SUNDAY NIGHT. SPEEDS WILL INCREASE
DURING THE MIDDLE OF NEXT WEEK BEFORE A SURFACE TROUGH / COOL
FRONT PASSES.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
257 PM CDT Thu Aug 21 2014
.SHORT TERM...(This evening through Friday)
ISSUED AT 255 PM CDT THU AUG 21 2014
18Z/1pm surface analysis shows stationary frontal boundary extending
from northern Iowa to southern Lake Michigan. Scattered convection
continues to develop and track along this boundary, mainly impacting
locations north of the I-80 corridor. An outflow boundary is
evident on visible satellite imagery dropping southeastward across
eastern Iowa and this may trigger isolated showers/thunder across
the far northwest KILX CWA this afternoon into the early evening.
Aside from this possible convection, the next round of significant
precip will likely hold off until late tonight when 30-35kt LLJ
develops from the southern Plains northeastward into Iowa. As this
jet interacts with the frontal boundary, a cluster of thunderstorms
will develop across eastern Iowa/northwest Illinois toward midnight,
then will track E/SE across north-central Illinois overnight.
Models continue to struggle with exact placement and track of
convection, with the 12z NAM once again appearing to be too
aggressive with its southward push of precip into the CWA tonight.
Prefer the Rapid Refresh model solution which keeps most of the
convection confined to locations along/northeast of the I-74
corridor. As a result, will carry likely PoPs after midnight
northeast of I-74, tapering down to just slight chances further
south along a Springfield to Paris line. Thunderstorm complex will
track into Indiana Friday morning, resulting in decreasing PoPs
across the board. With frontal boundary well to the north and upper
heights rising across the area, mainly dry weather will be on tap
Friday afternoon. High temperatures will reach the upper 80s and
lower 90s. These readings combined with dewpoints in the lower to
middle 70s will produce heat index values of around 100 degrees,
with readings approaching 105 degrees across the S/SE CWA, where a
Heat Advisory will be issued beginning Friday afternoon.
&&
.LONG TERM...(Friday night through Thursday)
ISSUED AT 255 PM CDT THU AUG 21 2014
12Z forecast models continue to build a strong upper level ridge
over IL this weekend and lingers over the Ohio River valley early
next work week. This will bring the longest and strongest heat wave
of the summer to central and southeast IL with highs in the low to
mid 90s from Friday through Tue and dewpoints peaking in the mid 70s
from late morning into early evening. This giving afternoon heat
indices of 98-106F and highest in sw counties where a heat
advisory will be issued from Friday afternoon through Monday
afternoon. Heat indices could even peak around 105F sw counties
this weekend. Southeast IL will continue to have heat indices of
100-105F Tuesday afternoon so heat advisory may need to be
extended with future updates. Due to uncertainty of convection
chances and possibly more cloud cover at times over ne counties
Fri and Sat, especially from I-74 ne, kept them out of heat advisory
but will issue SPS product to ahead heat indices reaching 100F or
even a few degree higher at time through early next week.
Another short wave riding se over top off upper level ridge across
northern/ne IL could bring 20-30% chance of showers and
thunderstorms to ne CWA especially from I-74 ne Friday night and
then shifting further ne during the day Saturday with just slight
pops ne areas. Upper level ridge appears strong enough over
central/se IL to keep convection chances ne of area from Saturday
night through Monday.
Models have trended slower with bringing a frontal boundary se into
NW IL Monday night/Tue and trimmed pops and confined them further nw
during that time. Also went a bit warmer with highs Monday and
Tuesday due to slower frontal movement and upper level ridge holding
longer over central/se IL. Better chance of showers and
thunderstorms appears to now be Wed/Thu time frame with upper level
trof starting to dig more into the upper Midwest and driving front
further southeast into central IL Wed and toward the Ohio river
valley on Thursday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1241 PM CDT THU AUG 21 2014
Scattered convection continues to track along a nearly stationary
frontal boundary draped across far northern Illinois/southern
Wisconsin early this afternoon. This activity will remain north of
the central Illinois terminals through this evening. Main aviation
question will be when/where additional nocturnal convection will
develop later tonight. Once again the NAM seems too aggressive in
driving precip southward into the area tonight, while the HRRR is
completely dry through 04z. Prefer a compromise solution as seen
on the latest Rapid Refresh model, which features a cluster of
showers/storms developing across eastern Iowa by around midnight,
then tracking E/SE across north-central Illinois overnight. Based
on this model, have introduced VCTS at the I-74 terminals between
07z and 09z. Further south, have gone completely dry at both KSPI
and KDEC through the night. Once any early morning convection
clears the area, dry weather is anticipated after 14z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY from 1 PM Friday to 7 PM CDT Monday FOR ILZ042-
047>054-056-061>063-066>068-071>073.
&&
$$
SHORT TERM...BARNES
LONG TERM...07
AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
208 PM CDT THU AUG 21 2014
.DISCUSSION...
1155 AM CDT
THE AFTERNOON FORECAST HAS BEEN UPDATED TO REFLECT COOLER
TEMPERATURES AND INCREASE POPS FOR THE NORTHERN FORECAST AREA. IT
REMAINS CHALLENGING TO GET VERY SPECIFIC WITH REGARD TO TIMING
THUNDERSTORM CHANCES.
EARLY THIS AFTERNOON...THE SYNOPTIC WARM FRONT EXTENDS FROM
NORTHERN IA THROUGH FAR NORTHERN IL AND TO THE MI/IN BORDER. THIS
FEATURE IS SOMEWHAT BAGGY OVER OUR AREA DUE TO OUTFLOW BOUNDARIES
AND CLOUDS FROM EARLIER ACTIVITY KEEPING THE MAIN BAROCLINIC ZONE
SOUTH OF THE WIND SHIFT AND MORE SO IN THE SOUTHERN FORECAST AREA.
PROFILERS INDICATE 15 TO 25 KT WESTERLY FLOW IN THE 850-925MB
LAYER WITH WEAK TO MODEST ISENTROPIC ASCENT ALONG THIS BOUNDARY.
AREAS OF MORE FOCUSED ASCENT ARE BASICALLY IN TANDEM WITH
MULTIPLE SHORT WAVES...WITH THE ONES OF INTEREST OVER SOUTHERN WI
AND WESTERN/CENTRAL IA. THESE FEATURES WILL CONTINUE TO SUPPORT
AREAS OF SHOWERS WORTHY OF LIKELY TO CATEGORICAL RAIN CHANCES FOR
THE NORTHERN FORECAST AREA. ELEVATED INSTABILITY IS ON THE ORDER
OF 400-700 J/KG PER THE 12Z DVN SOUNDING AND RAP ANALYSIS...SO
THUNDER COVERAGE IS LIKELY TO REMAIN LESS THAN RAIN COVERAGE
THROUGH EARLY AFTERNOON...AND AT TIMES HAS ONLY BEEN ISOLATED.
THE WESTERN WAVE OVER IA IS ONE OF A LITTLE MORE INTEREST AS THAT
COMES EASTWARD. HIGH RESOLUTION MODELS HAVE A SURPRISINGLY LARGE
SPREAD IN SOLUTIONS WITH THIS...WITH THE RAP BEING A FURTHER SOUTH
ONE. RADAR AND SATELLITE TRENDS ARE SUPPORTING THIS HOWEVER. AS
THIS MOVES EASTWARD THERE COULD BE A RESULTANT UPTICK IN THUNDER
COVERAGE DURING THE LATTER AFTERNOON INTO EARLY EVE...BUT LAPSE
RATES ARE POOR AND LIKELY WILL CONTINUE TO BE SO...COMMON WITH A
HIGH PWAT ATMOSPHERE AND NO SIGNIFICANT DIFFERENTIAL TEMPERATURE
ADVECTION. THE BETTER WARM AIR ADVECTION AND MOISTURE TRANSPORT
DEVELOP OVER THE MIDWEST LATER THIS EVENING...AND AN EVEN LARGER
SPREAD IN MODELS EXIST WITH THIS. AS SUCH...HAVE NOT MADE ANY
MAJOR CHANGES TO TONIGHTS POPS YET. THERE STILL LOOKS TO BE A
HEAVY RAINFALL THREAT WITHIN THE GENERAL REGION...BUT SPECIFICS
ARE QUITE DIFFICULT TO LOCK IN.
THE BOUNDARY SHOULD STRUGGLE TO MOVE MUCH NORTHWARD THIS AFTERNOON
DUE TO THE AREAS OF RAIN. THE SHOWERS AND WARM AIR ADVECTION
ALONG THE FRONTAL ZONE WILL HELP SUPPORT CLOUDS AND KEEP
TEMPERATURES COOLER. HIGHS LOOK TO STAY BELOW 80 FOR SOME
COMMUNITIES IN NORTHERN IL. UPPER 80S ARE STILL FAVORED ACROSS
THE FAR SOUTHERN FORECAST AREA WHERE SCATTERING OF CLOUDS AND
INCREASING SOUTHWEST SURFACE FLOW WILL FURTHER WARMING.
MTF
//PREV DISCUSSION...
330 AM CDT
SHORT TERM...THROUGH THURSDAY NIGHT...
FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND
THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC
ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER
SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS
IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER
MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE
RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO
FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE
THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED
OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA
COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED
BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE
SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL
THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS
THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS
WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE
SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT
THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE
AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED
OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO
GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE.
SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL
FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE
UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE
MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE
OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER.
LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED
CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL
BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS
ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE
UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE
EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE
THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS
TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE
CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD
FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL
PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES.
HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS
SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME
URBAN AND SMALL STREAM TYPE FLOODING ISSUES.
KREIN
FRIDAY THROUGH SUNDAY...
MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A
PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH.
GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE
FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED
FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST
INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS
EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE
CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE
ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS
CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO
THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY
LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80.
THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING
HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH
INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS
FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY
SAT.
OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT
THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL
BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING
LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF
THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN
THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK
CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES
BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE
SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE
WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO
BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH
OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE
CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH
WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE
ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN
THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST
AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO
POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS
WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL
LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH
AS 105 SUN AFTN FOR AREAS SOUTH OF I-80.
MONDAY THROUGH WEDNESDAY...
GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR
WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON
AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE
DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER
HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS
UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH
COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST
HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL
FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE
ROBUST RIDGE WILL OCCUR.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH A CHANCE
LATE THIS AFTERNOON...AND AGAIN OVERNIGHT.
* LOWER CEILINGS OR VISIBILITY FRIDAY MORNING
* POTENTIAL EAST WINDS FRIDAY AFTERNOON BUT GENERALLY UNDER 10 KT
KMD
//DISCUSSION...UPDATED 18Z...
THUNDER HAS REMAINED WEST AND NORTH WITH THE CURRENT BAND OF
SHOWER ACTIVITY THAT WILL PUSH THROUGH NORTHEAST ILLINOIS IN THE
NEXT FEW HOURS. THERE IS ANOTHER AREA OF THUNDERSTORMS THAT
CONTINUES TO ORGANIZE IN EASTERN IOWA THAT WILL GET AN ADDITIONAL
SHOVE EASTWARD LATER THIS AFTERNOON AS A SHORT WAVE IN WESTERN
CENTRAL IOWA SPREADS INTO ILLINOIS AND THEN SOUTHEASTWARD INTO
INDIANA THIS EVENING. THIS MAY BRING A PERIOD OF SHOWERS OR
THUNDERSTORMS TO THE TERMINALS DURING THE LATE AFTERNOON INTO THE
EARLY EVENING PERIOD. HAVE GONE WITH SHOWERS FOR NOW GIVEN RECENT
TRENDS BUT THIS MAY BE A PERIOD DURING THE AFTERNOON-EARLY EVENING
RUSH WHERE THERE MAY BE THUNDER IN THE VICINITY AND IS A PERIOD WE
WILL MONITOR IN THE COMING HOURS.
THEN THERE APPEARS TO BE A BREAK IN THE EVENING TIME FRAME AS
UPPER LEVEL FORCING DIMINISHES. WARM AIR ADVECTION THEN RAMPS BACK
UP IN WEST CENTRAL IOWA. IF THIS ACTIVITY GETS MOVING INTO
ILLINOIS IT LOOKS TO COME THROUGH OVERNIGHT. THEREFORE PUSHED THE
GOING PROB30 BACK TO ACCOUNT FOR THIS TIME FRAME.
THERE MAY ALSO BE SOME LOWER CLOUDS OR REDUCED VISIBILITIES LATE
TONIGHT INTO EARLY FRIDAY AFTER ADDITIONAL CONVECTIVE ACTIVITY
WINDS DOWN AND WINDS SLACKEN.
KMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-HIGH IN PERIODS OF SHOWERS THIS AFTERNOON...HIGH IN NO
THUNDER FOR THE NEXT FEW HOURS. LOW IN THUNDER CHANCES LATER
THIS AFTERNOON. LOW- MEDIUM IN THUNDER CHANCES TONIGHT AND LOW
IN TIMING.
* LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION
EXCEPT AROUND SHOWERS.
* LOW IN WIND DIRECTION FRIDAY AFTERNOON
KMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
* FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA
WITH OCNL MVFR CIGS/VIS.
KREIN
&&
.MARINE...
205 PM CDT
THE WEATHER PATTERN WILL NOT CHANGE MUCH OVER LAKE MICHIGAN
THROUGH THIS WEEKEND WITH LOW PRESSURE ACROSS THE CENTRAL PLAINS AND
HIGH PRESSURE OVER ONTARIO. A FRONT EXTENDING EAST FROM THE LOW IS
PRESENTLY DRAPED ACROSS THE FAR SOUTHERN PART OF THE LAKE AND THIS
WILL MOVE LITTLE THROUGH EARLY FRIDAY BEFORE SHIFTING BACK
SOUTH OF THE LAKE ON FRIDAY NIGHT. SOME THUNDERSTORMS ACROSS THE
SOUTHERN PART OF THE LAKE LATE THIS AFTERNOON MAY CAUSE SOME
VARIABILITY AND SLIGHTLY ENHANCED GUSTS IN THE WINDS...BUT ANY OF
THIS SHOULD BE TEMPORARY. THE WINDS WILL THEN TURN SOUTHERLY
ACROSS THE ENTIRE LAKE BY SUNDAY WITH THE LOW PRESSURE LIFTING
NORTH INTO SOUTHERN CANADA BY SUNDAY NIGHT. SPEEDS WILL INCREASE
DURING THE MIDDLE OF NEXT WEEK BEFORE A SURFACE TROUGH / COOL
FRONT PASSES.
MTF
&&
.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:
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WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
115 PM CDT THU AUG 21 2014
.DISCUSSION...
1155 AM CDT
THE AFTERNOON FORECAST HAS BEEN UPDATED TO REFLECT COOLER
TEMPERATURES AND INCREASE POPS FOR THE NORTHERN FORECAST AREA. IT
REMAINS CHALLENGING TO GET VERY SPECIFIC WITH REGARD TO TIMING
THUNDERSTORM CHANCES.
EARLY THIS AFTERNOON...THE SYNOPTIC WARM FRONT EXTENDS FROM
NORTHERN IA THROUGH FAR NORTHERN IL AND TO THE MI/IN BORDER. THIS
FEATURE IS SOMEWHAT BAGGY OVER OUR AREA DUE TO OUTFLOW BOUNDARIES
AND CLOUDS FROM EARLIER ACTIVITY KEEPING THE MAIN BAROCLINIC ZONE
SOUTH OF THE WIND SHIFT AND MORE SO IN THE SOUTHERN FORECAST AREA.
PROFILERS INDICATE 15 TO 25 KT WESTERLY FLOW IN THE 850-925MB
LAYER WITH WEAK TO MODEST ISENTROPIC ASCENT ALONG THIS BOUNDARY.
AREAS OF MORE FOCUSED ASCENT ARE BASICALLY IN TANDEM WITH
MULTIPLE SHORT WAVES...WITH THE ONES OF INTEREST OVER SOUTHERN WI
AND WESTERN/CENTRAL IA. THESE FEATURES WILL CONTINUE TO SUPPORT
AREAS OF SHOWERS WORTHY OF LIKELY TO CATEGORICAL RAIN CHANCES FOR
THE NORTHERN FORECAST AREA. ELEVATED INSTABILITY IS ON THE ORDER
OF 400-700 J/KG PER THE 12Z DVN SOUNDING AND RAP ANALYSIS...SO
THUNDER COVERAGE IS LIKELY TO REMAIN LESS THAN RAIN COVERAGE
THROUGH EARLY AFTERNOON...AND AT TIMES HAS ONLY BEEN ISOLATED.
THE WESTERN WAVE OVER IA IS ONE OF A LITTLE MORE INTEREST AS THAT
COMES EASTWARD. HIGH RESOLUTION MODELS HAVE A SURPRISINGLY LARGE
SPREAD IN SOLUTIONS WITH THIS...WITH THE RAP BEING A FURTHER SOUTH
ONE. RADAR AND SATELLITE TRENDS ARE SUPPORTING THIS HOWEVER. AS
THIS MOVES EASTWARD THERE COULD BE A RESULTANT UPTICK IN THUNDER
COVERAGE DURING THE LATTER AFTERNOON INTO EARLY EVE...BUT LAPSE
RATES ARE POOR AND LIKELY WILL CONTINUE TO BE SO...COMMON WITH A
HIGH PWAT ATMOSPHERE AND NO SIGNIFICANT DIFFERENTIAL TEMPERATURE
ADVECTION. THE BETTER WARM AIR ADVECTION AND MOISTURE TRANSPORT
DEVELOP OVER THE MIDWEST LATER THIS EVENING...AND AN EVEN LARGER
SPREAD IN MODELS EXIST WITH THIS. AS SUCH...HAVE NOT MADE ANY
MAJOR CHANGES TO TONIGHTS POPS YET. THERE STILL LOOKS TO BE A
HEAVY RAINFALL THREAT WITHIN THE GENERAL REGION...BUT SPECIFICS
ARE QUITE DIFFICULT TO LOCK IN.
THE BOUNDARY SHOULD STRUGGLE TO MOVE MUCH NORTHWARD THIS AFTERNOON
DUE TO THE AREAS OF RAIN. THE SHOWERS AND WARM AIR ADVECTION
ALONG THE FRONTAL ZONE WILL HELP SUPPORT CLOUDS AND KEEP
TEMPERATURES COOLER. HIGHS LOOK TO STAY BELOW 80 FOR SOME
COMMUNITIES IN NORTHERN IL. UPPER 80S ARE STILL FAVORED ACROSS
THE FAR SOUTHERN FORECAST AREA WHERE SCATTERING OF CLOUDS AND
INCREASING SOUTHWEST SURFACE FLOW WILL FURTHER WARMING.
MTF
//PREV DISCUSSION...
330 AM CDT
SHORT TERM...THROUGH THURSDAY NIGHT...
FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND
THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC
ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER
SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS
IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER
MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE
RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO
FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE
THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED
OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA
COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED
BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE
SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL
THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS
THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS
WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE
SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT
THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE
AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED
OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO
GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE.
SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL
FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE
UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE
MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE
OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER.
LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED
CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL
BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS
ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE
UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE
EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE
THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS
TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE
CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD
FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL
PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES.
HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS
SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME
URBAN AND SMALL STREAM TYPE FLOODING ISSUES.
KREIN
FRIDAY THROUGH SUNDAY...
MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A
PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH.
GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE
FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED
FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST
INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS
EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE
CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE
ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS
CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO
THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY
LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80.
THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING
HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH
INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS
FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY
SAT.
OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT
THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL
BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING
LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF
THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN
THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK
CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES
BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE
SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE
WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO
BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH
OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE
CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH
WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE
ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN
THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST
AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO
POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS
WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL
LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH
AS 105 SUN AFTN FOR AREAS SOUTH OF I-80.
MONDAY THROUGH WEDNESDAY...
GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR
WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON
AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE
DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER
HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS
UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH
COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST
HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL
FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE
ROBUST RIDGE WILL OCCUR.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH A CHANCE
LATE THIS AFTERNOON...AND AGAIN OVERNIGHT.
* LOWER CEILINGS OR VISIBILITY FRIDAY MORNING
* POTENTIAL EAST WINDS FRIDAY AFTERNOON BUT GENERALLY UNDER 10 KT
KMD
//DISCUSSION...UPDATED 18Z...
THUNDER HAS REMAINED WEST AND NORTH WITH THE CURRENT BAND OF
SHOWER ACTIVITY THAT WILL PUSH THROUGH NORTHEAST ILLINOIS IN THE
NEXT FEW HOURS. THERE IS ANOTHER AREA OF THUNDERSTORMS THAT
CONTINUES TO ORGANIZE IN EASTERN IOWA THAT WILL GET AN ADDITIONAL
SHOVE EASTWARD LATER THIS AFTERNOON AS A SHORT WAVE IN WESTERN
CENTRAL IOWA SPREADS INTO ILLINOIS AND THEN SOUTHEASTWARD INTO
INDIANA THIS EVENING. THIS MAY BRING A PERIOD OF SHOWERS OR
THUNDERSTORMS TO THE TERMINALS DURING THE LATE AFTERNOON INTO THE
EARLY EVENING PERIOD. HAVE GONE WITH SHOWERS FOR NOW GIVEN RECENT
TRENDS BUT THIS MAY BE A PERIOD DURING THE AFTERNOON-EARLY EVENING
RUSH WHERE THERE MAY BE THUNDER IN THE VICINITY AND IS A PERIOD WE
WILL MONITOR IN THE COMING HOURS.
THEN THERE APPEARS TO BE A BREAK IN THE EVENING TIME FRAME AS
UPPER LEVEL FORCING DIMINISHES. WARM AIR ADVECTION THEN RAMPS BACK
UP IN WEST CENTRAL IOWA. IF THIS ACTIVITY GETS MOVING INTO
ILLINOIS IT LOOKS TO COME THROUGH OVERNIGHT. THEREFORE PUSHED THE
GOING PROB30 BACK TO ACCOUNT FOR THIS TIME FRAME.
THERE MAY ALSO BE SOME LOWER CLOUDS OR REDUCED VISIBILITIES LATE
TONIGHT INTO EARLY FRIDAY AFTER ADDITIONAL CONVECTIVE ACTIVITY
WINDS DOWN AND WINDS SLACKEN.
KMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-HIGH IN PERIODS OF SHOWERS THIS AFTERNOON...HIGH IN NO
THUNDER FOR THE NEXT FEW HOURS. LOW IN THUNDER CHANCES LATER
THIS AFTERNOON. LOW- MEDIUM IN THUNDER CHANCES TONIGHT AND LOW
IN TIMING.
* LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION
EXCEPT AROUND SHOWERS.
* LOW IN WIND DIRECTION FRIDAY AFTERNOON
KMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
* FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA
WITH OCNL MVFR CIGS/VIS.
KREIN
&&
.MARINE...
310 AM CDT
NOT MUCH IN THE WAY OF A GRADIENT FOR THE NEXT SEVERAL DAYS...WITH
WEAK SYSTEMS EXPECTED. HIGH PRESSURE OVER QUEBEC AND A SERIES OF
WEAK TROUGHS OVER THE NORTHERN PLAINS. THERE WILL BE A QUASI-
STATIONARY FRONTAL BOUNDARY THAT WILL MEANDER NORTH AND SOUTH
ACROSS LAKE MICHIGAN...ALLOWING WINDS TO CHANGE DIRECTION BUT
STILL NOT EXPECTING MUCH OF A WIND GRADIENT TO DEVELOP. THE
HIGHEST WINDS WILL LIKELY BE ASSOCIATED WITH ANY THUNDERSTORMS
THAT CAN PRODUCE BRIEF GUSTS.
BEACHLER
&&
.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:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1158 AM CDT THU AUG 21 2014
.DISCUSSION...
1155 AM CDT
THE AFTERNOON FORECAST HAS BEEN UPDATED TO REFLECT COOLER
TEMPERATURES AND INCREASE POPS FOR THE NORTHERN FORECAST AREA. IT
REMAINS CHALLENGING TO GET VERY SPECIFIC WITH REGARD TO TIMING
THUNDERSTORM CHANCES.
EARLY THIS AFTERNOON...THE SYNOPTIC WARM FRONT EXTENDS FROM
NORTHERN IA THROUGH FAR NORTHERN IL AND TO THE MI/IN BORDER. THIS
FEATURE IS SOMEWHAT BAGGY OVER OUR AREA DUE TO OUTFLOW BOUNDARIES
AND CLOUDS FROM EARLIER ACTIVITY KEEPING THE MAIN BAROCLINIC ZONE
SOUTH OF THE WIND SHIFT AND MORE SO IN THE SOUTHERN FORECAST AREA.
PROFILERS INDICATE 15 TO 25 KT WESTERLY FLOW IN THE 850-925MB
LAYER WITH WEAK TO MODEST ISENTROPIC ASCENT ALONG THIS BOUNDARY.
AREAS OF MORE FOCUSED ASCENT ARE BASICALLY IN TANDEM WITH
MULTIPLE SHORT WAVES...WITH THE ONES OF INTEREST OVER SOUTHERN WI
AND WESTERN/CENTRAL IA. THESE FEATURES WILL CONTINUE TO SUPPORT
AREAS OF SHOWERS WORTHY OF LIKELY TO CATEGORICAL RAIN CHANCES FOR
THE NORTHERN FORECAST AREA. ELEVATED INSTABILITY IS ON THE ORDER
OF 400-700 J/KG PER THE 12Z DVN SOUNDING AND RAP ANALYSIS...SO
THUNDER COVERAGE IS LIKELY TO REMAIN LESS THAN RAIN COVERAGE
THROUGH EARLY AFTERNOON...AND AT TIMES HAS ONLY BEEN ISOLATED.
THE WESTERN WAVE OVER IA IS ONE OF A LITTLE MORE INTEREST AS THAT
COMES EASTWARD. HIGH RESOLUTION MODELS HAVE A SURPRISINGLY LARGE
SPREAD IN SOLUTIONS WITH THIS...WITH THE RAP BEING A FURTHER SOUTH
ONE. RADAR AND SATELLITE TRENDS ARE SUPPORTING THIS HOWEVER. AS
THIS MOVES EASTWARD THERE COULD BE A RESULTANT UPTICK IN THUNDER
COVERAGE DURING THE LATTER AFTERNOON INTO EARLY EVE...BUT LAPSE
RATES ARE POOR AND LIKELY WILL CONTINUE TO BE SO...COMMON WITH A
HIGH PWAT ATMOSPHERE AND NO SIGNIFICANT DIFFERENTIAL TEMPERATURE
ADVECTION. THE BETTER WARM AIR ADVECTION AND MOISTURE TRANSPORT
DEVELOP OVER THE MIDWEST LATER THIS EVENING...AND AN EVEN LARGER
SPREAD IN MODELS EXIST WITH THIS. AS SUCH...HAVE NOT MADE ANY
MAJOR CHANGES TO TONIGHTS POPS YET. THERE STILL LOOKS TO BE A
HEAVY RAINFALL THREAT WITHIN THE GENERAL REGION...BUT SPECIFICS
ARE QUITE DIFFICULT TO LOCK IN.
THE BOUNDARY SHOULD STRUGGLE TO MOVE MUCH NORTHWARD THIS AFTERNOON
DUE TO THE AREAS OF RAIN. THE SHOWERS AND WARM AIR ADVECTION
ALONG THE FRONTAL ZONE WILL HELP SUPPORT CLOUDS AND KEEP
TEMPERATURES COOLER. HIGHS LOOK TO STAY BELOW 80 FOR SOME
COMMUNITIES IN NORTHERN IL. UPPER 80S ARE STILL FAVORED ACROSS
THE FAR SOUTHERN FORECAST AREA WHERE SCATTERING OF CLOUDS AND
INCREASING SOUTHWEST SURFACE FLOW WILL FURTHER WARMING.
MTF
&&
.PREV DISCUSSION...
330 AM CDT
SHORT TERM...THROUGH THURSDAY NIGHT...
FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND
THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC
ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER
SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS
IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER
MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE
RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO
FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE
THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED
OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA
COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED
BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE
SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL
THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS
THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS
WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE
SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT
THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE
AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED
OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO
GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE.
SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL
FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE
UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE
MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE
OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER.
LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED
CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL
BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS
ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE
UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE
EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE
THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS
TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE
CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD
FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL
PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES.
HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS
SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME
URBAN AND SMALL STREAM TYPE FLOODING ISSUES.
KREIN
FRIDAY THROUGH SUNDAY...
MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A
PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH.
GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE
FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED
FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST
INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS
EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE
CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE
ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS
CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO
THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY
LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80.
THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING
HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH
INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS
FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY
SAT.
OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT
THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL
BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING
LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF
THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN
THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK
CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES
BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE
SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE
WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO
BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH
OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE
CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH
WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE
ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN
THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST
AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO
POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS
WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL
LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH
AS 105 SUN AFTN FOR AREAS SOUTH OF I-80.
MONDAY THROUGH WEDNESDAY...
GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR
WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON
AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE
DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER
HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS
UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH
COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST
HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL
FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE
ROBUST RIDGE WILL OCCUR.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH LOW CHANCES
THIS AFTERNOON...AND BETTER CHANCES THIS EVENING AND OVERNIGHT.
* SWLY WINDS GUSTING UP TO 20KT IN THE AFTERNOON.
KMD
//DISCUSSION...UPDATED 12Z..
PRIMARY FORECAST CONCERN WILL REMAIN THE CHANCES FOR THUNDERSTORMS
OVER THE AREA. AT ISSUANCE TIME...WIDESPREAD SHOWERS AND
THUNDERSTORMS COVER NRN IL/NWRN IN. THIS ACTIVITY IS DEVELOPING
ALONG AN ELEVATED WARM FRONT WITH INDIVIDUAL CELLS TRACKING TO THE
SOUTHEAST UNDER NWLY FLOW ARND 30KT ALOFT. THE WHOLE AREA OF PCPN
IS SLOWLY TRANSLATING TO THE EAST AS AN UPPER RIDGE BUILDS OVER
THE MIDDLE/UPPER MISSISSIPPI VALLEY...SO THUNDERSTORMS SHOULD
IMPACT THE TERMINALS THROUGH THE MORNING. HAVE GONE WITH
PREVAILING THUNDER RIGHT OUT OF THE GATE AND ADJUSTED THE INITIAL
TEMPO GROUP MORE TO COVER THE POSSIBILITY FOR PERIODS OF MVFR
CIGS/VIS UNDER THE PCPN SHIELD. TIMING OF BREAKS IN THE ACTIVITY
TODAY IS DIFFICULT AS THE MAIN BAROCLINIC ZONE WILL REMAIN IN
PLACE ALOFT THROUGH THE DAY. LATEST HIGH RES MODEL GUIDANCE
SUGGESTS THAT THE BEST OPPORTUNITY FOR A LULL IN THE ACTIVITY WILL
BE DURG THE AFTERNOON HOURS WHEN WEAK SHORTWAVE RIDGING MOVES OVER
THE REGION. THERE SHOULD BE ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH A SHORTWAVE CURRENTLY MOVING THROUGH
ERN NEBRASKA. ANTICIPATE THAT THIS SHORTWAVE SHOULD TRAVERSE THE
REGION BY LATE THIS EVENING GENERATING MORE SHRA/TSRA OVERNIGHT
TONIGHT. THERE IS ALSO THE POSSIBILITY THAT THIS SHORTWAVE COULD
PHASE WITH THE SHORTWAVE MOVING THROUGH MINNESOTA AND IF THAT
HAPPENS...THE COVERAGE OF SHRA/TSRA COULD BE MORE EXTENSIVE FOR A
LONGER PERIOD OF TIME. THE SHRA/TSRA POTENTIAL SHOULD COME TO AN
END BY EARLY TOMORROW MORNING AS THE UPPER RIDGE BUILDS EAST
ACROSS IL/WI/THE WESTERN GREAT LAKES REGION. AS PCPN ENDS...THERE
COULD BE A PERIOD OF LINGERING MVFR CIGS/VIS INTO LATE FRIDAY
MORNING.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH IN SHOWERS THIS AFTERNOON...LOW-MEDIUM IN NO THUNDER OR
THIS AFTERNOON. LOW-MEDIUM IN THUNDER CHANCES AND TIMING TONIGHT.
* LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION
EXCEPT AROUND SHOWERS.
KMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
* FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA
WITH OCNL MVFR CIGS/VIS.
KREIN
&&
.MARINE...
310 AM CDT
NOT MUCH IN THE WAY OF A GRADIENT FOR THE NEXT SEVERAL DAYS...WITH
WEAK SYSTEMS EXPECTED. HIGH PRESSURE OVER QUEBEC AND A SERIES OF
WEAK TROUGHS OVER THE NORTHERN PLAINS. THERE WILL BE A QUASI-
STATIONARY FRONTAL BOUNDARY THAT WILL MEANDER NORTH AND SOUTH
ACROSS LAKE MICHIGAN...ALLOWING WINDS TO CHANGE DIRECTION BUT
STILL NOT EXPECTING MUCH OF A WIND GRADIENT TO DEVELOP. THE
HIGHEST WINDS WILL LIKELY BE ASSOCIATED WITH ANY THUNDERSTORMS
THAT CAN PRODUCE BRIEF GUSTS.
BEACHLER
&&
.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 CHICAGO/ROMEOVILLE IL
1126 AM CDT THU AUG 21 2014
.MESOSCALE DISCUSSION...815 AM CDT
THE FORECAST HAS BEEN UPDATED TO RAISE POPS AND QPF IN EASTERN
AREAS THIS MORNING AS WELL AS ADJUST HOURLY FORECAST TRENDS OF
OTHER ELEMENTS.
A SHORT WAVE CENTER OVER NORTH CENTRAL IL IS MOVING ALONG THE
ELEVATED WARM AIR ADVECTION PATTERN. FORCING AHEAD OF THIS WITHIN
HIGH PWAT AIR /1.82 INCHES ON 12Z DVN RAOB/ HAS LED TO SOME
EFFICIENT RAINFALL RATES. MUCH OF THE THUNDERSTORM ACTIVITY
HAS BEEN PROGRESSIVE WITH JUST NUISANCE TYPE FLOODING REPORTS.
THIS WAVE SHOULD EXIT THE EASTERN FORECAST AREA BY 10 AM. CONTINUED
WARM AIR ADVECTION MAY SUPPORT SCATTERED STORMS ACROSS MAINLY
NORTHERN IL LATE THIS MORNING ALTHOUGH WITH THE VEERED LOW-LEVEL
JET PER PROFILERS AND THE 12Z DVN RAOB...ORGANIZATION OR MAJOR
INTENSIFICATION IS NOT ANTICIPATED. SUCH SCATTERED ACTIVITY HAS
ALREADY BEEN SEEN ACROSS FAR NORTHWEST IL AND SOUTHWEST WI. THERE
HAS BEEN WARMING OF CLOUD TOPS ON IR WITH THESE STORMS.
THE LOW-LEVEL FRONTAL ZONE IS DRAPED OUT FROM WEST TO EAST ACROSS
THE FORECAST AREA. IT IS TOUGH TO SAY WHERE FOR CERTAIN BUT LOOKS
LIKE IT HAS BEEN CONVECTIVELY DISRUPTED FROM ITS EARLIER NORTH
PLACEMENT. THIS SHOULD BEGIN TO SHIFT SLOWLY BACK NORTH BY EARLY
AFTERNOON BUT WILL BE AN IMPORTANT FEATURE FOR
PLACEMENT/MORPHOLOGY OF ANY AFTERNOON AND EVENING CONVECTION.
MTF
&&
.DISCUSSION...
330 AM CDT
SHORT TERM...THROUGH THURSDAY NIGHT...
FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND
THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC
ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER
SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS
IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER
MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE
RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO
FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE
THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED
OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA
COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED
BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE
SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL
THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS
THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS
WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE
SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT
THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE
AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED
OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO
GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE.
SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL
FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE
UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE
MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE
OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER.
LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED
CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL
BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS
ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE
UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE
EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE
THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS
TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE
CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD
FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL
PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES.
HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS
SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME
URBAN AND SMALL STREAM TYPE FLOODING ISSUES.
KREIN
FRIDAY THROUGH SUNDAY...
MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A
PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH.
GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE
FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED
FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST
INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS
EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE
CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE
ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS
CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO
THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY
LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80.
THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING
HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH
INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS
FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY
SAT.
OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT
THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL
BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING
LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF
THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN
THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK
CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES
BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE
SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE
WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO
BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH
OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE
CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH
WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE
ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN
THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST
AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO
POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS
WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL
LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH
AS 105 SUN AFTN FOR AREAS SOUTH OF I-80.
MONDAY THROUGH WEDNESDAY...
GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR
WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON
AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE
DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER
HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS
UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH
COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST
HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL
FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE
ROBUST RIDGE WILL OCCUR.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH LOW CHANCES
THIS AFTERNOON...AND BETTER CHANCES THIS EVENING AND OVERNIGHT.
* SWLY WINDS GUSTING UP TO 20KT IN THE AFTERNOON.
KMD
//DISCUSSION...UPDATED 12Z..
PRIMARY FORECAST CONCERN WILL REMAIN THE CHANCES FOR THUNDERSTORMS
OVER THE AREA. AT ISSUANCE TIME...WIDESPREAD SHOWERS AND
THUNDERSTORMS COVER NRN IL/NWRN IN. THIS ACTIVITY IS DEVELOPING
ALONG AN ELEVATED WARM FRONT WITH INDIVIDUAL CELLS TRACKING TO THE
SOUTHEAST UNDER NWLY FLOW ARND 30KT ALOFT. THE WHOLE AREA OF PCPN
IS SLOWLY TRANSLATING TO THE EAST AS AN UPPER RIDGE BUILDS OVER
THE MIDDLE/UPPER MISSISSIPPI VALLEY...SO THUNDERSTORMS SHOULD
IMPACT THE TERMINALS THROUGH THE MORNING. HAVE GONE WITH
PREVAILING THUNDER RIGHT OUT OF THE GATE AND ADJUSTED THE INITIAL
TEMPO GROUP MORE TO COVER THE POSSIBILITY FOR PERIODS OF MVFR
CIGS/VIS UNDER THE PCPN SHIELD. TIMING OF BREAKS IN THE ACTIVITY
TODAY IS DIFFICULT AS THE MAIN BAROCLINIC ZONE WILL REMAIN IN
PLACE ALOFT THROUGH THE DAY. LATEST HIGH RES MODEL GUIDANCE
SUGGESTS THAT THE BEST OPPORTUNITY FOR A LULL IN THE ACTIVITY WILL
BE DURG THE AFTERNOON HOURS WHEN WEAK SHORTWAVE RIDGING MOVES OVER
THE REGION. THERE SHOULD BE ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH A SHORTWAVE CURRENTLY MOVING THROUGH
ERN NEBRASKA. ANTICIPATE THAT THIS SHORTWAVE SHOULD TRAVERSE THE
REGION BY LATE THIS EVENING GENERATING MORE SHRA/TSRA OVERNIGHT
TONIGHT. THERE IS ALSO THE POSSIBILITY THAT THIS SHORTWAVE COULD
PHASE WITH THE SHORTWAVE MOVING THROUGH MINNESOTA AND IF THAT
HAPPENS...THE COVERAGE OF SHRA/TSRA COULD BE MORE EXTENSIVE FOR A
LONGER PERIOD OF TIME. THE SHRA/TSRA POTENTIAL SHOULD COME TO AN
END BY EARLY TOMORROW MORNING AS THE UPPER RIDGE BUILDS EAST
ACROSS IL/WI/THE WESTERN GREAT LAKES REGION. AS PCPN ENDS...THERE
COULD BE A PERIOD OF LINGERING MVFR CIGS/VIS INTO LATE FRIDAY
MORNING.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH IN SHOWERS THIS AFTERNOON...LOW-MEDIUM IN NO THUNDER OR
THIS AFTERNOON. LOW-MEDIUM IN THUNDER CHANCES AND TIMING TONIGHT.
* LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION
EXCEPT AROUND SHOWERS.
KMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
* FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA
WITH OCNL MVFR CIGS/VIS.
KREIN
&&
.MARINE...
310 AM CDT
NOT MUCH IN THE WAY OF A GRADIENT FOR THE NEXT SEVERAL DAYS...WITH
WEAK SYSTEMS EXPECTED. HIGH PRESSURE OVER QUEBEC AND A SERIES OF
WEAK TROUGHS OVER THE NORTHERN PLAINS. THERE WILL BE A QUASI-
STATIONARY FRONTAL BOUNDARY THAT WILL MEANDER NORTH AND SOUTH
ACROSS LAKE MICHIGAN...ALLOWING WINDS TO CHANGE DIRECTION BUT
STILL NOT EXPECTING MUCH OF A WIND GRADIENT TO DEVELOP. THE
HIGHEST WINDS WILL LIKELY BE ASSOCIATED WITH ANY THUNDERSTORMS
THAT CAN PRODUCE BRIEF GUSTS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1015 AM CDT Thu Aug 21 2014
.UPDATE...
ISSUED AT 1015 AM CDT THU AUG 21 2014
15z/10am surface analysis shows warm front extending from northern
Iowa to southern Lake Michigan. Numerous showers and thunderstorms
have been tracking along this boundary early this morning, mainly
impacting locations along/north of the I-80 corridor. This is a
bit further north than previously forecast, thanks to the upper
ridge building across the region. 12z NAM keeps central Illinois
dry throughout the day, then develops nocturnal convection as far
south as the I-72 corridor late tonight. NAM was too aggressive
with the southward extent of precip last night, so am skeptical
of its latest solution. HRRR is also dry through the day, and
does not develop any convection across the area through 03z this
evening. Based on latest satellite/radar trends and NAM/HRRR data,
have trimmed PoPs today and tonight. Will maintain slight chance
for showers/thunder across the far N and E CWA through the
morning, then will go with dry conditions across the board this
afternoon. Have also reduced PoPs for tonight, focusing highest
chances across the north from the Peoria and Bloomington areas
northward after midnight. With a good deal of sunshine and
southwesterly winds, afternoon highs will reach the upper 80s and
lower 90s.
&&
.SHORT TERM...(Today and Tonight)
ISSUED AT 342 AM CDT THU AUG 21 2014
Warm front has lifted north through most of the area and based on
surface observations, looks to be just north of I-74 at this point.
Believe the front will continue to lift north through the day,
resulting in the whole CWA being in the warm sector for the end of
the week. However, the mid level ridge will be somewhat flat and any
disturbance or wave that moves along the top of the ridge could
result in precip dropping into the northern and northeastern part of
the CWA. So chance pops will continue to be warranted over parts of
the CWA today and tonight. Pops will be less during the daytime
hours but then increase over the northeastern half of the CWA for
the overnight hours, tonight. Temperatures will be warm today, but
cloud cover could keep afternoon highs from getting too high, though
still expecting highs around 90 today. Lows tonight will be similar
to now, just about 1-2 degrees warmer.
&&
.LONG TERM...(Friday through Wednesday)
ISSUED AT 342 AM CDT THU AUG 21 2014
Summer heat continues through the remains of the weekend. Hot and
humid conditions lending to an isolated thunderstorm threat through
the weekend, particularly towards the NE as waves push over the
upper ridge building into the Midwest. Models shifting with each
issuance as to the actual increased threat with the erosion of the
ridging to the NE. Heat and humidity has been more consistent,
though even that has seen some shifts, starting to retract some of
the eastward creep of the 850 mb temps. Not pulling back too much
in the way of guidance just yet and temps Fri-Sun still in the 90s,
heat indices over 100F. Issuance of a Heat Advisory covered
above...however, should the dwpts materialize, or see the temps
respond as expected behind this mornings warm front today... will
rethink the issuance of a Heat Advisory for the weekend as these
temps are not only well above normal, but more impactful after such
a mild summer so far. Into the extended, day 6/just into day 8,
models have gone back to a divergence in solutions as the GFS is
more progressive with the next upper trof moving a cold front
through with storms and cooler temps in the wake...while the 00Z
ECMWF is now cutting off the low over the NW, extending the ridges
hold over the region.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 626 AM CDT THU AUG 21 2014
The warm front has lifted north of all the TAF sites and all pcpn
has moved north or east of the sites this morning. So most of the
day all sites will be pcpn free. So, there will be some high CU/SC
today with some cirrus early and then maybe some AC later this
morning. Then by this afternoon, skies should become scattered.
Clouds will then be on the increase around midnight as a complex
of storms will develop west of the area and move along the warm
front tonight. This should bring broken AC clouds to SPI and DEC,
but VCTS and broken SC/CU at PIA/BMI/CMI. Winds will be southwest,
but become southerly this evening for a brief time, then back to
southwest around midnight. Wind speeds will be around 7-10kts
through the period.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...AUTEN
LONG TERM...HJS
AVIATION...AUTEN
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
155 PM EDT THU AUG 21 2014
.SYNOPSIS...
ISSUED AT 154 PM EDT THU AUG 21 2014
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION WILL BECOME
MORE LIKELY TONIGHT AS A COUPLE OF UPPER LEVEL DISTURBANCES
APPROACH. HIGHS TODAY WILL BE IN THE LOWER TO MID 80S. LOWS THE
NEXT SEVERAL NIGHTS WILL BE AROUND 70. HIGHS THIS WEEKEND WILL BE
AROUND 90 DEGREES.
&&
.UPDATE...
ISSUED AT 1128 AM EDT THU AUG 21 2014
BROAD ISENTROPIC LIFT/LOW LEVEL MOISTURE TRANSPORT WILL CONTINUE
THROUGH THIS AFTERNOON FROM THE MID MS RIVER VALLEY EXTENDING
EASTWARD TO THE OHIO RIVER VALLEY. RUC INITIALIZATION SUPPORT
CONVECTIVE ENHANCEMENT TO SMALL SCALE VORT MAX TRACKING ACROSS
SOUTH/SOUTHEAST PORTIONS OF THE AREA THIS MORNING...WITH SOME
INDICATIONS OF MCV HAVING ALSO FORMED ACROSS FAR NORTH CENTRAL
INDIANA. A BRIEF LULL IN PRECIP IS POSSIBLE IN WAKE OF THIS
FEATURE OVER NEXT FEW HOURS...BUT A STEADY STREAM OF SMALLER SCALE
WAVES EMBEDDED IN NORTHWEST UPPER FLOW AND POOLED LOW LEVEL
MOISTURE AXIS ACROSS MUCH OF LOCAL AREA WILL SUPPORT AT LEAST
CHANCE TSRA MENTION THROUGH THE REMAINDER OF THE AFTERNOON.
SLIGHTLY MORE STABLE CONDITIONS ASSOCIATED WITH MORNING
CLOUDS/PRECIP MAY TEMPER SEVERE THREAT AT LEAST THROUGH MUCH OF
THE AFTERNOON HOURS. POCKET OF STRONGER MID/UPPER FLOW IS EXPECTED
TO OVERSPREAD THE AREA THIS EVENING AND THIS MAY SUPPORT SOUTHEAST
PROPAGATION OF POTENTIAL CONVECTIVE SYSTEM FORMING UPSTREAM OF
LOCAL AREA TONIGHT. RADAR ESTIMATES THAT MANY LOCATIONS FROM
WESTERN STARKE COUNTY INTO GRANT COUNTY HAVE EXPERIENCED 1 TO 2
INCHES OF RAINFALL WITH MORNING STORMS...AND SOME HYDRO CONCERNS
MAY EVOLVE TONIGHT DEPENDING ON UPSTREAM LATE AFTERNOON/EVENING
CONVECTIVE EVOLUTION...BUT WILL HOLD OFF ON ANY HYDRO HEADLINES AT
THIS TIME.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 449 AM EDT THU AUG 21 2014
UPPER LEVEL JET DYNAMICS COMBINED WITH THE LEADING EDGE OF THETA E
CONVERGENCE WAS HELPING TO TRIGGER ISOLATED STORMS AND AN AREA OF
SHOWERS NORTH OF THE FRONT. THE STORMS WERE HIGH BASED EARLY THIS
MORNING...BUT SHOULD BECOME MORE SURFACE BASED AS THE FRONT MOVES
NORTH AND AS THE ATMOSPHERE DESTABILIZES WITH DAYTIME HEATING LATER
TODAY. THETA E FLUX WILL INCREASE TONIGHT...WITH A BETTER CHANCE FOR
SHOWERS AND STORMS AS AN UPPER LEVEL DISTURBANCE TOPS THE UPSTREAM
RIDGE AND MOVES INTO THE WESTERN GREAT LAKES REGION. THE 12KM NAM
APPEARED TO HAVE A REASONABLE HANDLE ON THE TIMING OF THIS UPSTREAM
SYSTEM AND THE TRACK OVER THE UPPER LEVEL RIDGE...SO HAVE LIKELY
THUNDERSTORM CHANCES LATER TONIGHT. SEVERE STORMS ARE POSSIBLE GIVEN
DEEP LAYER SHEAR TOPPING OUT AT 30 TO 40 KNOTS. HAVE RAISED HIGHS
TODAY. THE NAM/MET HAS RAISED HIGHS TODAY 5 DEGREES AT SBN AND
APPEARS ON TRACK...COMING MORE IN LINE WITH THE GFS/MAV. 850 MB
TEMPS WILL BE BETWEEN 18C AND 19C TODAY...AND SOME SUN TODAY SHOULD
ALLOW HIGHS TO RISE TO BETWEEN 82F AND 86F.
&&
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 449 AM EDT THU AUG 21 2014
MAIN CONCERN THIS PERIOD IS POTENTIAL FOR EXCESSIVE HEAT AS STRONG
UPR LEVEL RIDGE BUILDS INTO THE AREA RESULTING IN HEAT INDEX
READINGS IN THE 90S EACH AFTN. ALTHOUGH THESE READINGS ARE A BIT
BLO OUR ADVISORY CRITERIA... IMPACTS MAY BE GREATER THAN USUAL DUE
TO EXPECTED RATHER LONG DURATION OF THE HEAT WAVE... AND
DIFFICULTY FOR PEOPLE TO BECOME ACCLIMATED TO THE HEAT GIVEN
ABNORMALLY COOL TEMPS THUS FAR THIS SUMMER.
CONVECTION AT NOSE OF A WK WLY LLJ MAY BE ONGOING IN OUR AREA AT
THE START OF THE PERIOD FRIDAY MORNING. WK LOW LEVEL WAA PATTERN
AND STNRY SFC BOUNDARY DRAPED ACROSS NERN PORTION OF THE CWA
EXPECTED FRI WHICH MAY PROVIDE FOCUS FOR REDEVELOPMENT IN THE AFTN
AS AIRMASS DESTABILIZES. THIS BOUNDARY EXPECTED TO REMAIN OVER THE
AREA FRI NGT WITH NOSE OF WSWLY LLJ OVER THE MID MS VALLEY
PROVIDING FORCING FOR CONVECTION UPSTREAM OVERNIGHT WHICH COULD BE
SUSTAINED INTO OUR AREA GIVEN LINGERING WK/MODERATE ELEVATED
INSTABILITY. RATHER STRONG NWLY UPR LEVEL FLOW ON EAST SIDE OF MS
VALLEY RIDGE WILL PROVIDE DECENT DEEP LAYER SHEAR FRI/FRI
NGT...ESPECIALLY OVER ERN PORTIONS OF THE CWA WHICH ALSO COULD AID
IN CONVECTIVE PERSISTENCE AS WELL AS SUPPORT A FEW STRONG/SVR
STORMS AROUND PEAK HEATING FRI AFTN/EVE. DOUBT CONVECTION WILL BE
SUFFICIENTLY WIDESPREAD OR LAST LONG ENOUGH TO HOLD TEMPS DOWN
SIGNIFICANTLY FRIDAY. GIVEN H85 TEMPS PROGGED IN THE 19-20C RANGE
STAYED CLOSE TO PREVIOUS FCST WITH HIGHS RANGING FROM THE M80S NE
TO AROUND 90 SW. DWPTS SHOULD ALSO BE RISING TO THE L-M70S WHICH
WILL RESULT IN AFTN HEAT INDICES ABOUT 5-10F HIGHER THAN TEMPS.
LIGHT WINDS FRI NGT SHOULD ALLOW FOR SOME RADIATIONAL COOLING SO
EXPECT MINS TO BE IN THE U60S NE AND L70S SW.
SIMILAR CONDITIONS EXPECTED SATURDAY. UPR RIDGE AXIS SHOULD MOVE
SLIGHTLY EAST INTO OUR AREA AS STRONG TROF MOVES ACROSS THE NRN
ROCKIES. E-W ORIENTED SURFACE BOUNDARY WILL LIKELY REMAIN OVER THE
AREA PROVIDING SOME FOCUS FOR CONVECTION AS AIRMASS DESTABILIZES
DURING THE DAY. WK LOW LEVEL GRADIENT WINDS AND VERY MOIST AIRMASS
OVER THE AREA SHOULD AGAIN LIMIT HEATING BUT EXPECT SUFFICIENT
MIXING TO ALLOW FOR HIGHS CLOSE TO FRIDAYS READINGS AS SUGGESTED BY
MAV MOS TEMPS.
STNRY SFC BOUNDARY SHOULD LIFT NORTH OF OUR CWA SAT NGT-SUNDAY AS
SFC LOW DEEPENS OVER THE NRN PLAINS. THIS SHOULD RESULT IN MAINLY
DRY CONDITIONS BY SUNDAY WITH TEMPS CONTG TO SLOWLY WARM. NRN PLAINS
LOW EXPECTED TO LIFT NE-E INTO ONTARIO MONDAY AND TO QUEBEC TUE WITH
TRAILING WK CDFNT DROPPING SOUTH INTO OUR AREA BY THAT TIME. SOME
SUPPRESSION OF UPR RIDGE PER ECMWF SOLUTION SEEMS APPROPRIATE AS
SHRTWV BREAKS OVER THE TOP ACROSS THE UPR GRTLKS... SO WKNG CAPPING
INVERSION/CHC TSTMS... AND SLIGHTLY LOWER TEMPS FCST BY TUE. MEDIUM
RANGE MODELS DIFFERING SOLUTIONS WRT PERSISTENCE OF UPR RIDGE TUE
LEADING TO EVEN GREATER DIFFERENCES BY WED WITH ECMWF SUGGESTING
RIDGING BUILDING BACK INTO OUR REGION AS CLOSED LOW DEVELOPS IN
THE WRN U.S., WHILE GFS FCSTG MORE PROGRESSIVE WRN TROF WITH A STRONG
SHRTWV APPROACHING THE MIDWEST BY WED EVE. GIVEN LARGE DIFFERENCES
STAYED CLOSE TO PREVIOUS FCST WHICH WAS FOR CONTD SLOW COOLING
TREND AND A LOW CHC OF TSTMS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 129 PM EDT THU AUG 21 2014
FIRST WAVE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO EXIT
NORTHEAST INDIANA OVER THE NEXT FEW HOURS...WITH ATTENTION FOR
REMAINDER OF AFTERNOON AND EVENING TURNING UPSTREAM WITH A COUPLE
OF ADDITIONAL SHORT WAVE PROGRESSING THROUGH UPPER RIDGE. SOME
LINGERING IFR CONDITIONS WILL PERSIST OVER THE NEXT HOUR OR TWO
BEFORE IMPROVING AFTER 20Z. THE NEXT SHORT WAVE ACROSS SOUTHERN
WISCONSIN SHOULD ALLOW SHOWERS TO MOVE BACK INTO NORTH CENTRAL
INDIANA LATE THIS AFTERNOON. A RELATIVE STABLE BUBBLE PERSISTS
ACROSS NORTH CENTRAL INDIANA IN REGARDS TO SFC BASED CONVECTIVE
POTENTIAL...BUT SUSPECTING ENOUGH ELEVATED INSTABILITY WILL BE
PRESENT FOR SOME THUNDER POTENTIAL AS THE SRN WISCONSIN SHORT
WAVE SHIFTS EASTWARD THIS AFTERNOON. BETTER CHANCE OF THUNDER
STILL APPEARS TO BE IN STORE FOR LATE EVENING INTO THE OVERNIGHT
AS NEXT UPSTREAM IOWA SHORT WAVE APPROACHES THE AREA WITH
PERSISTENT ISENTROPIC UPGLIDE ASSOCIATED WITH LOW LEVEL BOUNDARY
ACROSS THE REGION. HAVE KEPT IN VCSH MENTION AFTER 12Z WITH A MORE
MUDDLED PICTURE AT THIS FORECAST DISTANCE IN TERMS OF LATCHING
ONTO ANY SIGNIFICANT ADDITIONAL SHORT WAVES. GRADUALLY MID LEVEL
HEIGHT RISES TOWARD THE END OF THE PERIOD SHOULD DIMINISH
CONVECTIVE POTENTIAL LATER FRIDAY AFTERNOON.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
UPDATE...MARSILI
SYNOPSIS...MARSILI
SHORT TERM...SKIPPER
LONG TERM...JT
AVIATION...MARSILI
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AREA FORECAST DISCUSSION
NWS WICHITA KS
305 PM CDT THU AUG 21 2014
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 252 PM CDT THU AUG 21 2014
TNGT-SAT: ANOTHER HOT AFTERNOON UNDER WAY ACROSS THE FORECAST AREA
TODAY...AS BREEZY SOUTHWEST WINDS ARE LEADING TO TEMPS SLIGHTLY
WARMER THAN THE PREVIOUS FEW DAYS. SURFACE DEWPOINTS MIXING OUT A
LITTLE BETTER OVER SOUTH CENTRAL KS...BUT NOT AS FAST OVER SE
KS...SO COULD SEE HEAT INDEX VALUES HOVER NEAR 105 FOR AN HOUR OR
TWO LATE THIS AFTERNOON...ESPECIALLY OVER SE KS.
MID/UPPER LEVEL FLOW IS MORE OUT OF THE SW THIS AFTERNOON...WITH
LATEST WATER VAPOR IMAGERY SHOWING A NICE MOISTURE PLUME OUT OF THE
SW US FROM THE MONSOONAL FLOW INTO SW KS. LATEST SURFACE ANALYSIS
SHOWS SURFACE TROUGH LOCATED GENERALLY JUST EAST OF KGLD TO NEAR
KGCK. INSTABILITY AXIS CONTINUES ALONG THIS BOUNDARY WITH SBCAPES
VALUES OF 2500-2800 J/KG. THE COMBINATION OF THE HEAT AND UNSTABLE
AIRMASS...IS EXPECTED TO ERODE THE CAP AND DEVELOP STORMS ALONG THIS
INSTABILITY AXIS LATE THIS AFTERNOON INTO THIS EVENING.
ANY CONVECTION OVER WRN KS WILL SLOWLY MOVE TO THE NORTHEAST AS THE
LATE EVENING PROGRESSES...AS LOW LEVEL MOISTURE TRANSPORT FROM THE
OK PANHANDLE INCREASES ALONG THE WRN EDGE OF THE FORECAST AREA. SO
EXPECT STORMS TO MOVE INTO CENTRAL KS LATE THIS EVENING...WITH SOME
BACKBUILDING POSSIBLE ACROSS PORTIONS OF CENTRAL KS AT LEAST UNTIL
MIDNIGHT. EXPECT MOST OF THE CONVECTION TO BE LOCATED ALONG OR NORTH
OF HIGHWAY 56 FROM GREAT BEND TO MCPHERSON AS MOISTURE TRANSPORT
FOCUSES THE CONVECTION IN THIS AREA AND MORE TO THE NORTHEAST
TOWARDS KMHK AFTER MIDNIGHT. SO WILL KEEP CHANCE POPS GOING FOR THIS
CHANCE.
NOT EXPECTING MUCH OF CHANGE IN HOW THE GOING FORECAST WILL PLAY
OUT FRI/SAT...WITH HOT TEMPS DURING THE DAYTIME HOURS...WITH BETTER
MIXING IN WRN SECTIONS OF THE FORECAST AREA. SO MAX TEMPS IN THE
MID-UPPER 90S WILL BE COMMON...BUT BETTER MIXING OF SURFACE
DEWPOINTS WILL KEEP HEAT INDEX VALUES IN THE 100-104 RANGE.
WILL ALSO SEE A VIRTUAL REPEAT OF THE CONVECTIVE CHANCES FOR FRI/SAT
AS WELL...AS THE SURFACE BOUNDARY REMAINS JUST TO THE WEST OF THE
FORECAST AREA...WITH AFTERNOON/EVENING CONVECTION MOVING NORTHEAST
OVER PORTIONS OF CENTRAL KS FOR BOTH FRI AND SAT NIGHTS.
KETCHAM
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 252 PM CDT THU AUG 21 2014
SUN-TUE: SW FLOW CONTINUES ACROSS THE HIGH PLAINS THROUGH THE END
OF THE WEEKEND INTO THE BEGINNING OF THE WEEK...WITH EACH
SUCCESSIVE SHORTWAVE IN THE FLOW HELPING TO PUSH THE FRONTAL
BOUNDARY A LITTLE CLOSER TOWARDS THE FORECAST AREA FOR SUN. BOTH
THE GFS AND ECMWF SHOW THIS BOUNDARY DRIFTING INTO THE FORECAST
AREA FOR SUN-SUN NIGHT. THIS TIME FRAME LOOKS LIKE THE BEST CHANCE
FOR WIDELY SCATTERED SHOWERS/STORMS...ESPECIALLY FOR AREAS WEST OF
THE KS TURNPIKE.
CHANCE FOR STORMS LOOKS A LITTLE MORE UNCERTAIN FOR MON/TUE...AS
POSITION OF THE BOUNDARY OVER THE FORECAST AREA WILL BE IN
QUESTION. BOTH THE GFS AND ECMWF BOTH SUGGEST THAT THE BOUNDARY
WILL BE LOCATED SOMEWHERE OVER SRN KS...AND POSSIBLY WASH OUT OVER
THE AREA BY TUE. THINK STORM CHANCES WILL HAVE ALOT OF MESOSCALE
EFFECTS...SO HARD TO PIN DOWN WHERE THE BEST CHANCE OF STORMS WILL
BE LOCATED IN THE WEAKLY CAPPED ENVIRONMENT THAT WILL BE OVER THE
AREA.
REST OF THE EXTENDED: LOTS OF UNCERTAINTY ON HOW THE MIDDLE OF THE
WEEK WILL EVOLVE...AS THE MEDIUM RANGE MODELS CANT DECIDE ON WHAT
TO DO WITH TEMPS/PRECIP AS A MORE POTENT SHORTWAVE MOVES OUT OF
THE SW FLOW AND ACROSS THE NRN PLAINS. GFS IS A LOT MORE
PROGRESSIVE WITH THE TIMING OF THIS SHORTWAVE...BRINGING IT ACROSS
THE PLAINS ON WED...WITH A COLD FRONT PUSHING SOME COOLER AIR INTO
THE PLAINS FOR WED THRU THE END OF THE WEEK. THE ECMWF ON THE
OTHER HAND IS A LOT SLOWER WITH THIS IMPULSE...HOLDING IT BACK
UNTIL LATER IN THE WEEK...WHICH WOULD SUGGEST THAT THE HOT TEMPS
WILL STAY AROUND POSSIBLY THROUGH THU OR FRI. SO POPS FOR THIS
TIME FRAME WILL ALSO BE HIGHLY CONTINGENT ON WHEN THE BOUNDARY
MAKES ITS WAY ACROSS.
KETCHAM
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1256 PM CDT THU AUG 21 2014
THE MAIN FORECAST PROBLEM FOR THE NEXT 24 HOURS REMAINS
CONVECTION. THE HRRR MODEL RUNS THIS MORNING HAVE ALL CONTINUED TO
SHOW CONVECTIVE INITIATION IN AN AREA ROUGHLY FROM HUTCHINSON TO
DODGE CITY. THIS IS JUST AHEAD OF A STALLED FRONT. CONVERGENCE
ALONG THIS BOUNDARY IS FAVORABLE AND THE STRUCTURE OF THE
ATMOSPHERE HAS NOT SIGNIFICANTLY CHANGED MUCH.
THE HRRR FORECASTS FOR THE LAST SEVERAL DAYS HAVE BEEN PRETTY
ACCURATE AND THERE IS NO REASON TO THINK TODAYS WILL NOT BE. THAT
SAID...THE MODEL IS TRENDING TOWARD LESS PRECIPITATION MOVING
INTO NORTH-CENTRAL KANSAS...WHILE TRENDING MORE TOWARD STORMS
REMAINING SOUTH AND BUILDING SOUTH INTO THE TEXAS PAN HANDLE.
KEPT CONTINUITY IN THE TAFS FOR NOW. BEST TIME FOR CONVECTION TO
AFFECT THE TAFS IS FROM 00Z-05Z. THIS TIMING IS MUCH EARLIER THAN
THE LAMP OUTPUT...BUT MORE IN LINE WITH THE HRRR. THE LAMP OUTPUT
HAS BEEN TRENDING TOWARD THE HRRR.
COOK
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 77 98 75 97 / 10 10 10 0
HUTCHINSON 76 99 74 97 / 20 10 20 0
NEWTON 76 98 74 96 / 20 10 10 0
ELDORADO 77 98 74 97 / 10 10 10 0
WINFIELD-KWLD 77 98 75 98 / 0 10 10 0
RUSSELL 74 98 73 95 / 20 10 30 0
GREAT BEND 74 97 73 96 / 20 10 20 0
SALINA 77 100 74 97 / 20 10 20 0
MCPHERSON 76 98 74 96 / 20 10 20 0
COFFEYVILLE 76 98 74 98 / 0 10 0 0
CHANUTE 76 97 73 97 / 0 10 0 0
IOLA 76 97 73 97 / 0 10 0 0
PARSONS-KPPF 76 98 73 98 / 0 10 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
110 PM CDT THU AUG 21 2014
...UPDATED FOR 18Z AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 355 AM CDT THU AUG 21 2014
SCATTERED THUNDERSTORMS THAT HAVE BEEN OCCURRING FROM NORTHEAST CO TO
CENTRAL & EASTERN NEBRASKA HAVE BEEN OCCURRING ALONG A SLOW SE-MOVING
COLD FRONT CURVING FROM THE EASTERN DAKOTAS TO THE CO/NM BORDER. THE
DRIVING MECHANISM HAS BEEN A BROAD MID-LEVEL TROF EXTENDING FROM THE
WESTERN DAKOTAS TO EXTREME NORTHEAST NM. THIS PATTERN IS PRODUCING YET
ANOTHER VERY WARM NIGHT ACROSS THE WFO WICHITA PREMISES WHERE SOUTH 15
TO 25 MPH WINDS HAVE HELD TEMPERATURES TO THE LOWER 80S IN ALL AREAS.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 355 AM CDT THU AUG 21 2014
TODAY:
THE LARGE MID-UPPER HIGH COVERING THE GULF COAST REGION THAT HAS BEEN A
TOPIC THE PAST 3 NIGHTS IS BEHAVING AS EXPECTED...SPREADING SLOWLY WEST
ACROSS THE LOWER MS VALLEY. THIS WOULD FORCE THE BROAD MID-LEVEL TROUGH
SITUATED OVER THE WESTERN PLAINS NE ACROSS NEBRASKA WHERE IT`LL SHEAR
QUICKLY TODAY. THE RESULT: MORE DRY WEATHER FOR THE NEIGHBORHOOD TODAY.
TONIGHT:
THE FOCUS SHIFTS TO THUNDERSTORM POTENTIAL. PERSISTENT SURFACE TROFFING
ALONG THE FRONT RANGE WILL CONTINUE INDUCING FAIRLY RICH MOISTURE TO
MIGRATE NE ACROSS WESTERN & CENTRAL KS BUT MID-LEVEL DYNAMICS ARE A BIT
FEEBLE & WITH WARM MID LEVELS...THUNDERSTORM POTENTIAL WOULD BE LIMITED
WITH ANY CHANCES CONFINED TO CENTRAL KS.
FRI & FRI NIGHT:
AFTER ANOTHER HOT & BREEZY DAY A FEW THUNDERSTORMS MAY VENTURE INTO THE
NEIGHBORHOOD FROM WESTERN KS LATE TONIGHT AS A MORE ROBUST MID-LEVEL
SHORTWAVE QUICKLY STRENGTHENS OVER THE NEBRASKA PANHANDLE & NORTHEAST
CO BUT WITH THE MASSIVE MID-UPPER HIGH CONTINUING TO SPREAD/RETROGRADE
TOWARD THE SOUTHERN PLAINS THE SHORTWAVE WOULD BE FORCED NE TOWARD THE
NEBRASKA/SD BORDER. AS SUCH THE BETTER CHANCES OF THUNDERSTORMS WOULD
OCCUR ACROSS THE WESTERN HALF OF KS. HAVE ASSIGNED 20-30% POPS TO AREAS
PRIMARILY ALONG & W OF I-135.
SAT & SAT NIGHT:
WITH THE AFORE-MENTIONED INTENSE MID-LEVEL SHORTWAVE BEING "FORCED" TO
MOVE DUE N OVER THE DAKOTAS ON SAT HOT & DRY WEATHER WILL AGAIN GRIP
ALL AREAS ON SAT. THUNDERSTORM POTENTIAL SHOULD BEGIN TO INCREASE SAT
NIGHT AS INTENSE CYCLOGENESIS ENSUES OVER THE MT/ND BORDER. A MID-LEVEL
SHORTWAVE WILL SCOOT DUE EAST AROUND THE BASE OF CYCLONE TOWARD...THEN
ACROSS...THE CO/KS BORDER. THIS WOULD FORCE A COLD FRONT ESE ACROSS THE
CO/KS BORDER LATE SAT NIGHT. THUNDERSTORMS DEVELOPING OVER THE WESTERN
PLAINS WOULD SURGE E/NE TOWARD...THEN ACROSS...CENTRAL & SOUTH-CENTRAL
KS LATE SAT NIGHT & EARLY SUN MORNING.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 355 AM CDT THU AUG 21 2014
WHILE THUNDERSTORMS ARE CERTAINLY ANTICIPATED FOR SUN & SUN NIGHT THE
BETTER CHANCES ARE STILL EXPECTED TO OCCUR FROM MON NIGHT THRU TUE
NIGHT WHEN THE STRONGEST/MOST INTENSE MID-UPPER WAVE SURGES E ACROSS
KS & NEBRASKA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1256 PM CDT THU AUG 21 2014
THE MAIN FORECAST PROBLEM FOR THE NEXT 24 HOURS REMAINS
CONVECTION. THE HRRR MODEL RUNS THIS MORNING HAVE ALL CONTINUED TO
SHOW CONVECTIVE INITIATION IN AN AREA ROUGHLY FROM HUTCHINSON TO
DODGE CITY. THIS IS JUST AHEAD OF A STALLED FRONT. CONVERGENCE
ALONG THIS BOUNDARY IS FAVORABLE AND THE STRUCTURE OF THE
ATMOSPHERE HAS NOT SIGNIFICANTLY CHANGED MUCH.
THE HRRR FORECASTS FOR THE LAST SEVERAL DAYS HAVE BEEN PRETTY
ACCURATE AND THERE IS NO REASON TO THINK TODAYS WILL NOT BE. THAT
SAID...THE MODEL IS TRENDING TOWARD LESS PRECIPITATION MOVING
INTO NORTH-CENTRAL KANSAS...WHILE TRENDING MORE TOWARD STORMS
REMAINING SOUTH AND BUILDING SOUTH INTO THE TEXAS PAN HANDLE.
KEPT CONTINUITY IN THE TAFS FOR NOW. BEST TIME FOR CONVECTION TO
AFFECT THE TAFS IS FROM 00Z-05Z. THIS TIMING IS MUCH EARLIER THAN
THE LAMP OUTPUT...BUT MORE IN LINE WITH THE HRRR. THE LAMP OUTPUT
HAS BEEN TRENDING TOWARD THE HRRR.
COOK
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 99 77 97 75 / 10 10 10 10
HUTCHINSON 99 76 99 75 / 10 20 10 20
NEWTON 98 76 97 75 / 10 10 10 10
ELDORADO 98 77 98 75 / 10 10 10 10
WINFIELD-KWLD 99 77 97 76 / 0 0 10 10
RUSSELL 100 74 97 74 / 20 20 10 30
GREAT BEND 100 74 97 74 / 20 20 10 20
SALINA 101 77 99 75 / 10 20 10 20
MCPHERSON 100 76 98 75 / 10 20 10 20
COFFEYVILLE 98 76 97 74 / 10 0 0 0
CHANUTE 98 76 97 74 / 10 0 0 0
IOLA 97 76 97 74 / 10 0 0 0
PARSONS-KPPF 97 76 97 74 / 10 0 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
355 PM EDT THU AUG 21 2014
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 355 PM EDT THU AUG 21 2014
19Z SFC ANALYSIS SHOWS A SEASONALLY STRONG AREA OF LOW PRESSURE OVER
THE HIGH PLAINS WITH HIGH PRESSURE OVER THE DEEP SOUTH. THIS NEARBY
HIGH IS NOT ENOUGH TO PREVENT THE LATEST INCARNATION OF MCS ACTIVITY
FROM DIVING THROUGH EASTERN KENTUCKY. THIS IS TAKING ADVANTAGE OF
HIGH INSTABILITY THROUGHOUT THE AREA GIVEN TEMPERATURES IN THE UPPER
80S AND DEWPOINTS IN THE LOWER 70S. IN ADDITION TO THE SEVERE
THUNDERSTORM THREAT...HIGH PWS...LOW FFG...AND A POTENTIAL FOR
TRAINING WILL KEEP FLASH FLOODING A CONCERN THROUGH THE EVENING.
THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION
OF THE FORECAST WITH A LARGE AREA OF RIDGING STRETCHING FROM THE
LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY. AS IT DOES SO...A
DEEP LOW TO THE NORTHEAST WILL SEND PACKETS OF ENERGY THROUGH THE
OHIO VALLEY AND INTO THE CENTRAL APPALACHIANS IN FAIRLY FAST
NORTHWEST FLOW. THIS WILL PLACE AT LEAST NORTHEAST PARTS OF THE JKL
CWA IN THE STORM TRACK AND AS PRIME REAL ESTATE FOR MCS ACTIVITY.
GIVEN THE MODEL AGREEMENT HAVE FAVORED A BLEND WITH EXTRA EMPHASIS ON
THE HRRR AND NAM12 FOR THE FIRST 12 TO 24 HOURS.
SENSIBLE WEATHER WILL FEATURE ON GOING THUNDERSTORM ACTIVITY
DIMINISHING INTO THE EVENING...BUT PROGRESSING SOUTH WITH THE FAVORED
INSTABILITY. LATER TONIGHT...PARTLY CLOUDS SKIES AND THE MOISTURE
FROM THE RAIN OF THIS AFTERNOON AND EVENING WILL LIKELY LEAD TO
AREAS OF FOG...LOCALLY DENSE. INDICATIONS ARE THAT THE NEXT ROUND OF
STORMS STAY TO THE NORTHEAST OF THE CWA TONIGHT. AFTER THE FOG BURNS
OFF ON FRIDAY MORNING THE INSTABILITY WILL BUILD AGAIN WITH ANOTHER
VERY HUMID AND WARM DAY. THIS WILL BE A SIMILAR SETUP FOR SEVERE AND
EXCESSIVE RAIN POTENTIAL...MAINLY IN THE NORTHEAST BASED ON THE
EXPECTATION OF EARLY STORMS TRACKING JUST OUTSIDE OF THE CWA AND
DEVELOPMENT ON THEIR SOUTHWEST FLANKS. LIKEWISE...PATCHY FOG WILL BE
AN ISSUE FOR THE AREA LATER FRIDAY NIGHT GIVEN A SIMILAR SETUP...
BUT STILL DEPENDENT ON THE RAINS EARLY IN THE DAY AND EVENING.
USED THE CONSSHORT AS A STARTING POINT FOR THE T...TD...AND WINDS
THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME
MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND FRIDAY NIGHT.
AS FOR POPS...ENDED UP HIGHER THAN GUIDANCE...EXCEPT FOR THE MET
NORTH OF JKL ON FRIDAY NIGHT...THROUGH SATURDAY MORNING OWING TO THE
TENDENCY FOR STORMS TO EXPAND SOUTHWEST OF THEIR DEPICTIONS IN THE
MODELS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 315 PM EDT THU AUG 21 2014
STRONG RIDGING WILL LIKELY HOLD OVER THE AREA FOR THE BALANCE OF THE
EXTENDED PART OF THE FORECAST. SHOWER AND THUNDERSTORM CHANCES WILL
CONTINUE EACH DAY THROUGH THE MIDDLE OF NEXT WEEK. IN
ADDITION...WARM AND MUGGY CONDITIONS WILL REMAIN ANCHORED BENEATH
THE RIDGE. BEST TIME FOR SHOWERS AND STORMS WILL CONTINUE TO BE EACH
AFTERNOON/EVENING...BUT CANNOT RULE OUT AN ISOLATED SHOWER OR STORM
AT ANY TIME INTO NEXT WEEK. GFS MOS IS LIKELY A BIT TOO HIGH AND
WILL CONTINUE TO GO BETWEEN GFS AND MET MOS THROUGH SATURDAY. ECMWF
SEEMS TO BE A GOOD COMPROMISE WITH REGARDS TO TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 210 PM EDT THU AUG 21 2014
THE AVIATION FORECAST WILL BE A CHALLENGE WITH THE TIMING OF MCS
CLUSTERS AND POTENTIAL FOR FOG FORMATION THROUGH THE PERIOD. EXPECT
THE BETTER CHANCES FOR LOWER CIGS AND VIS ASSOCIATED WITH STORMS WILL
BE FOR THE NORTHERN TAF SITES THROUGH EARLY EVENING. THESE LOCATIONS
MAY HAVE A BETTER CHANCE FOR MORE IN THE WAY OF LOWER VIS PRODUCING
FOG. HOWEVER...THAT WILL BE DEPENDENT ON ADDED MOISTURE FROM
CONVECTION DURING THE REST OF THE DAY AND SOME CLEARING LATER
TONIGHT. FOR NOW...HAVE BROUGHT ALL THE SITES TO MVFR IN BR AFTER 06Z
AND CLEARING OUT...BACK TO VFR BY 14Z FRIDAY. CANNOT RULE OUT
ADDITIONAL STORMS FRIDAY AFTERNOON...ESPECIALLY NORTHEAST...BUT
THROUGH 18Z THE TAF SITES SHOULD REMAIN CALM. WINDS THROUGH THE NIGHT
WILL BE LIGHT AND VARIABLE...FAVORING THE SOUTHWEST AT 5 TO 10 KTS
DURING THE DAYLIGHT HOURS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GREIF
LONG TERM...KAS
AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
210 PM EDT THU AUG 21 2014
.UPDATE...
ISSUED AT 140 PM EDT THU AUG 21 2014
WITH AN AREA OF SCATTERED STORMS NOW MOVING EAST ALONG INTERSTATE 64
HAVE UPDATED THE FORECAST TO REFLECT THE HIGHER POPS NORTH OF THE
MOUNTAIN PARKWAY AND LOWER TEMPS THERE. ALSO ADDED MORE POPS IN THE
HIGHER TERRAIN OVER THE FAR SOUTHEAST AND LOWERED THEM ELSEWHERE FOR
THE NEXT FEW HOURS. AFTER THAT...OUTFLOWS FROM THE NORTHERN STORMS
WILL POTENTIALLY BRING CONVECTIVE DEVELOPMENT FURTHER SOUTH...AIDED
BY THE HIGHER INSTABILITY. IN ADDITION...MADE SOME TWEAKS TO THE
HOURLY TEMPS AND DEWPOINTS FOR THE REST OF THE AFTERNOON GIVEN THE
CURRENT OBS AND TRENDS. THESE UPDATED GRIDS HAVE BEEN SENT TO THE
NDFD AND WEB SERVERS.
UPDATE ISSUED AT 1050 AM EDT THU AUG 21 2014
14Z SFC ANALYSIS SHOW GENERAL LOW PRESSURE NORTH OF THE OHIO RIVER
WITH HIGHER PRESSURE FOUND TO THE SOUTH. A STATIONARY BOUNDARY EXISTS
THROUGH THE NORTHERN PORTIONS OF THE OHIO VALLEY AND WESTERN PARTS OF
THIS FRONT...CONNECTED BACK TO DEEPER LOW PRESSURE OVER THE NORTHERN
PLAINS...HAS BEEN A GENESIS REGION FOR RECENT MCS ACTIVITY. THIS
ACTIVITY IS ALSO SUPPORTED BY A STREAM OF MID LEVEL ENERGY RIDING
ALONG THE NORTHERN FRINGE OF A DEVELOPING RIDGE TO THE SOUTHWEST OF
KENTUCKY. THIS WOULD TEND TO SUPPORT CONVECTION WORKING SOUTHEAST
FROM THE UPPER MIDWEST TO THE CENTRAL APPALACHIANS PASSING BY JUST TO
OUR NORTHEAST. HOWEVER...INSTABILITY BUILDING WITH THE RECENT
ARRIVAL OF SUMMER TIME HEAT AND HUMIDITY ACROSS KENTUCKY WILL BE
ENOUGH TO KEEP A THREAT OF THE STORMS AND THEIR OUTFLOW BOUNDARIES
SNEAKING INTO NORTHEAST PORTIONS OF THE CWA AND PERHAPS FURTHER TO
THE SOUTHWEST IN THE AFTERNOON. THE CURRENT RADAR HAS A HEALTHY
CLUSTER OF STORMS CROSSING FROM INDIANA INTO OHIO WITH A GROWING
SOUTHERN EXTENT TRACKING THROUGH NORTHERN KENTUCKY. EXPECT THIS TO
BRUSH INTO NORTHERN PARTS OF THE FORECAST AREA THROUGH THE NEXT
SEVERAL HOURS. THE HRRR KEEPS THIS FIRST WAVE JUST NORTH OF THE
CWA...WHILE THE 12Z NAM12 DIPS THE CONVECTION DEEPER INTO EAST
KENTUCKY. FOR THIS UPDATE HAVE SPLIT THE DIFFERENCE BETWEEN THESE TWO
SCENARIOS AND PEAKED POPS IN THE NORTHEAST THROUGH THE AFTERNOON WITH
SOME SMALL TO MODERATE POPS EVEN DOWN INTO THE CUMBERLAND VALLEY BY
EVENING. HIGH PWS AND THE RAINS OF THE PAST SEVERAL DAYS WILL MEAN A
THREAT OF FLASH FLOODING FOR PLACES THAT SEE REPEATED STORMS...
PARTICULARLY THROUGH THE MID SECTION OF THE CWA. SPC HAS PLACED
EASTERN PARTS OF THE AREA...ALONG THE PREVIOUSLY DISCUSSED STORM
TRACK...IN A SLIGHT RISK FOR SEVERE WEATHER...MAINLY DAMAGING WINDS
AND LARGE HAIL. THIS APPEARS REASONABLE GIVEN THE HIGH CAPE...LOW
LIS...AND LACK OF A MID LEVEL CAP. ACCORDINGLY THIS CONCERN WILL
CONTINUE TO BE HIGHLIGHTED IN THE HWO ALONG WITH A MENTION OF THE
HEAT AND HUMIDITY...TEMPS NEAR 90 AND DEWPOINTS IN THE 70S...THROUGH
THE WEEKEND. HAVE ALSO FINE TUNED THE T AND TD GRIDS PER THE LATEST
OBS...TRENDS...AND CONSSHORT GUIDANCE. THESE UPDATES HAVE BEEN SENT
TO THE NDFD AND WEB SERVERS WITH NEW HWO AND ZONES ON THEIR WAY.
UPDATE ISSUED AT 757 AM EDT THU AUG 21 2014
THE FORECAST REMAINS ON TRACK THIS MORNING. FRESHENED UP THE HOURLY
TEMPERATURES...DEW POINTS...AND SKY COVER TO ACCOUNT FOR THE LATEST
TRENDS IN THE OBSERVATIONS.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 357 AM EDT THU AUG 21 2014
THE LATEST SURFACE MAP FEATURES HIGH PRESSURE ACROSS THE GULF COAST
STATES...WITH LOW PRESSURE ACROSS THE PLAINS STATES. A STATIONARY
BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE GREAT LAKES/OHIO
VALLEY REGION. ALOFT...AN UPPER LEVEL LOW CONTINUES TO SPIN ACROSS
THE NORTHERN GREAT LAKES...WITH AN UPPER LEVEL RIDGE CENTERED NEAR
THE NORTHERN GULF OF MEXICO...AND MORE TROUGHING FEATURED ACROSS
THE NORTHERN ROCKIES. SEVERAL COMPLEXES OF THUNDERSTORMS HAVE BEEN
GENERATING AND THEN RIDING SOUTHEAST ON THE PERIPHERY OF THE UPPER
LEVEL RIDGE OVER THE PAST FEW DAYS.
CURRENTLY...EASTERN KENTUCKY REMAINS QUIET AS ONLY A WEAKENING
SMALLER COMPLEX OF THUNDERSTORMS IS SLOWLY MOVING THROUGH SOUTHEAST
ILLINOIS AND SOUTHWEST INDIANA. THE NEXT MORE ORGANIZED COMPLEX IS
CURRENTLY MOVING THROUGH MINNESOTA.
THE MODEL GUIDANCE HAS BEEN ALL OVER THE PLACE WITH THE TIMING OF THE
MORE ORGANIZED CONVECTION AS OF LATE. AS SUCH...HAVE USED A GENERAL
BLEND OF THE GUIDANCE AND THE INHERITED FORECAST. AS THE UPPER LEVEL
RIDGE SLOWLY BUILDS INTO THE REGION THROUGH FRIDAY...IT WILL
GENERALLY NUDGE THE MCS TRACK FURTHER NORTHEAST...HOWEVER SINCE THERE
WILL BE PLENTY OF FUEL FOR THE STORMS AND A WEAK SYNOPTIC PATTERN IN
PLACE...CAN NOT RULE OUT OUTFLOW INFLUENCE FURTHER SOUTHWEST. SOME
STORMS COULD APPROACH SEVERE LIMITS...AND ISOLATED FLASH FLOODING
WILL ALSO BE A POSSIBILITY...ESPECIALLY WHERE STORMS CAN MOVE
PARALLEL TO ANY ESTABLISHED OUTFLOW BOUNDARIES. WILL HIGHLIGHT THESE
THREATS IN THE HWO. POPS WILL GENERALLY PEAK IN THE AFTERNOON HOURS
TODAY AND FRIDAY...WITH LESSER CHANCES DURING THE OVERNIGHT HOURS.
HIGHS TODAY WILL AVERAGE IN THE 85 TO 90 DEGREE RANGE...WITH AROUND
90 DEGREES EXPECTED FOR MOST LOCATIONS ON FRIDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 357 AM EDT THU AUG 21 2014
THE EXTENDED PORTION OF THE FORECAST BEGINS ON FRIDAY NIGHT WITH A
WELL DEVELOPED MID LEVEL RIDGE CENTERED OVER THE MID WEST AND
LONGWAVE TROUGH ENTERING THE NORTHWEST WITH AN EXITING TROUGH OVER
THE NORTHEAST. THE MID LEVEL RIDGE AXIS EVENTUALLY SHIFTS EAST OVER
THE OH VALLEY BY MONDAY AS IT WEAKENS A BIT WITH THE APPROACHING
TROUGH OVER THE NORTHERN PLAINS AND THE TROUGH OVER THE NORTHEAST
EXITING INTO THE ATLANTIC. THIS PATTERN BASICALLY KEEPS THE RIDGE
OVER EASTERN KENTUCKY THROUGH THE REST OF THE EXTENDED.
WITH THIS PATTERN IN PLACE THROUGH SUNDAY...EASTERN KENTUCKY REMAINS
IN NORTHWEST FLOW WITH STILL A FEW MCS/S LIKELY POISED TO TRACK
SOUTHEAST INTO THE AREA FOR THIS WEEKEND. WHILE MODELS INHERENTLY
WILL HAVE TROUBLE TRACKING THEM...THE FIRST ONE SHOULD BE MOVING
THROUGH FRIDAY NIGHT WITH THE NEXT ONE POSSIBLY SATURDAY NIGHT. BY
SUNDAY...THE RIDGE AXIS REALLY BEGINS TO SET IN AND ADDITIONAL
STRONG CONVECTION MAY BE LESS LIKELY AND MAY BE MORE TIED TO DIURNAL
PROCESSES WITH A STATIONARY BOUNDARY ALONG THE EASTERN PORTION OF THE
CWA. BY MONDAY AND THROUGH WEDNESDAY...THE MID LEVEL RIDGE AXIS
MOVES OVER THE AREA WHICH SHOULD EFFECTIVELY CUT OFF CONVECTION...AT
LEAST DEEP CONVECTION. SOME AFTERNOON SHOWERS AND POSSIBLY A STORM OR
TWO MAY DEVELOP UNDER THE RIDGE. THE SOLUTION OF THE ALL MODEL BLEND
WOULD SUGGEST SOME UNCERTAINTY THERE WITH THE BEST CHANCE OF PRECIP
FRIDAY NIGHT THROUGH SUNDAY. THIS IS IN GOOD AGREEMENT WITH THE GFS
AND EURO AS WELL. OVERALL THE BROAD BRUSH OF POPS THROUGH THE FIRST 3
DAYS OF THE EXTENDED SEEMS NEEDED DUE TO THE NATURE OF THE MODELS
HAVING TROUBLE DEPICTING THE COMPLEXES MOVING THROUGH BUT DID GO WITH
SOME DIURNAL CHARACTERISTICS.
BY THE END OF THE EXTENDED...THE MODELS SEEM TO HINT AT THE RIDGE
MOVING FARTHER EAST AS A STRONG SHORTWAVE AND ASSOCIATED COLD FRONT
SEEMS POISED TO MOVE THROUGH THE MS RIVER VALLEY AND INTO THE OH
VALLEY. IN ADDITION...THE WARM AND MUGGY WEATHER STILL LOOKS TO BE
ON TAP THROUGH THE WEEKEND WITH HIGHS AROUND 90 THROUGH MONDAY AND
DEW POINTS AROUND 70. THE END OF THE EXTENDED DOES SHOW SOME RELIEF
FROM THE WARM AND HUMID WEATHER WITH THE APPROACH OF THE
AFOREMENTIONED COLD FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 210 PM EDT THU AUG 21 2014
THE AVIATION FORECAST WILL BE A CHALLENGE WITH THE TIMING OF MCS
CLUSTERS AND POTENTIAL FOR FOG FORMATION THROUGH THE PERIOD. EXPECT
THE BETTER CHANCES FOR LOWER CIGS AND VIS ASSOCIATED WITH STORMS WILL
BE FOR THE NORTHERN TAF SITES THROUGH EARLY EVENING. THESE LOCATIONS
MAY HAVE A BETTER CHANCE FOR MORE IN THE WAY OF LOWER VIS PRODUCING
FOG. HOWEVER...THAT WILL BE DEPENDENT ON ADDED MOISTURE FROM
CONVECTION DURING THE REST OF THE DAY AND SOME CLEARING LATER
TONIGHT. FOR NOW...HAVE BROUGHT ALL THE SITES TO MVFR IN BR AFTER 06Z
AND CLEARING OUT...BACK TO VFR BY 14Z FRIDAY. CANNOT RULE OUT
ADDITIONAL STORMS FRIDAY AFTERNOON...ESPECIALLY NORTHEAST...BUT
THROUGH 18Z THE TAF SITES SHOULD REMAIN CALM. WINDS THROUGH THE NIGHT
WILL BE LIGHT AND VARIABLE...FAVORING THE SOUTHWEST AT 5 TO 10 KTS
DURING THE DAYLIGHT HOURS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1257 PM CDT THU AUG 21 2014
.AVIATION...
FOR THE 21/18Z TAFS...DENSE CU FIELD WITH CIGS GENERALLY BETWEEN
2500 AND 3000 FEET PERSISTS RESULTING IN A MIX OF MVFR/LOW-END VFR
FLIGHT CONDITIONS. CIGS SHOULD CONTINUE TO SLOWLY LIFT WHILE
OVERALL CLOUD COVER GRADUALLY THINS. SEA BREEZE CONVECTION IS
ALREADY DEVELOPING AND WILL LIKELY EXPAND IN COVERAGE SLIGHTLY BUT
SHOULD REMAIN SOUTH OF A LINE FROM KLFK TO KMLU. SHWRS/TSTMS
SHOULD DISSIPATE AROUND SUNSET. ANOTHER ROUND OF MVFR/IFR
CIGS/VSBYS ARE EXPECTED DURING THE OVERNIGHT/EARLY MORNING HRS
FRIDAY WITH SLOW IMPROVEMENT LATE IN THE TAF PERIOD. /09/
&&
.PREV DISCUSSION... /ISSUED 1035 AM CDT THU AUG 21 2014/
DISCUSSION...
LATEST VIS SATELLITE IMAGERY SHOWING EXPANSIVE STRATOCUMULUS DECK
ENCOMPASSING MOST OF THE FOUR STATE REGION THIS MORNING. CUMULUS
IS TAKING ON MORE OF A HORIZONTAL ROW APPEARANCE WHICH IS
INDICATIVE OF SOME MIXING BEGINNING TO TAKE PLACE IN THE LOWER
ATMOSPHERE AS HEATING TAKES PLACE. AS A RESULT...EXPECT SOME PEEKS
OF SUN TO BEGIN OVER THE NEXT COUPLE HOURS WITH EVENTUALLY SKIES
BECOMING PARTLY CLOUDY ACROSS THE REGION.
STRONG WINDS IN THE LOWEST 5KFT ALLOWED THE STRATUS TO MOVE
QUICKLY NORTHWARD AND CONDENSE EARLY THIS MORNING AND WE ARE
STARTING TO SEE SOME OF THIS MIX DOWN ACROSS NE TX THIS MORNING
WITH STRONGER WIND GUSTS NOTED NORTH AND WEST OF THE I-30 CORRIDOR
ACROSS TX.
LOOKING AT NEW RAW 12Z NAM OUTPUT...THERE REMAINS A WEAK SHEAR
AXIS ACROSS OUR EASTERN MOST ZONES EARLY THIS MORNING. WEAK BUT
OBVIOUS 850-700MB THETAE AXIS ALSO RESIDES ACROSS THIS GENERAL
AREA AND AS A RESULT...THIS WILL MOST LIKELY BE THE FAVORABLE
REGION TO SEE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS LATER
TODAY.
OTHERWISE...ONCE THE CLOUDS THIN...SHOULD HAVE NO PROBLEMS GETTING
TEMPERATURES TO REACH FCST MAX TEMPS WITH 15Z OBSERVATIONS ALREADY
RUNNING SOME 1 TO 3 DEGREES ABOVE THOSE EXPERIENCED ON WEDNESDAY
ATTM.
NO UPDATE NECESSARY TO THE FORECAST THIS MORNING.
13
PREV DISCUSSION... /ISSUED 435 AM CDT THU AUG 21 2014/
DISCUSSION...
11-3.9U SATELLITE IMAGERY THIS MORNING INDICATES A VORTICITY MAXIMUM
OVER NCNTRL LA...WHICH IS ALONG A ELEVATED WEAK SHEAR AXIS NOTED ON
THE WATER VAPOR LOOP EXTENDING FROM SE TX ACROSS NCNTRL LA INTO CNTRL
MS/NRN AL. THIS FEATURE HAS MAINTAINED AN EXTENSIVE AC CANOPY THIS
MORNING OVER MUCH OF NCNTRL LA...WHICH ARE THE CONVECTIVE REMNANTS OF
THE ISOLATED SEABREEZE CONVECTION THAT AFFECTED THESE AREAS WEDNESDAY
AFTERNOON AND EVENING. A WEAK UPPER LOW NOTED ON THE WATER VAPOR LOOP
NOW AFFECTING THE ERN MX COAST S OF BRO HAS ALREADY RESULTED IN
ENHANCED ONSHORE FLOW WHICH HAS LED TO INCREASED MOISTURE CONVERGENCE
ALONG A W TO E SFC TROUGH WHICH LIES NEAR THE I-10 CORRIDOR. THIS HAS
RESULTED IN ISOLATED CONVECTION DEVELOPING/STREAMING N ACROSS SW
LA...BUT HAVE WEAKENED WHERE SFC CONVERGENCE IS LOST FARTHER N OF THE
SFC TROUGH. THE PROGS DO WEAKEN THE VORT MAX LATER TODAY AS THE CENTER
OF THE 500MB RIDGE BEGINS TO BUILD NNW INTO THE LOWER MS VALLEY...BUT
SHOULD STILL SEE ANOTHER DAY WHERE SEABREEZE CONVECTION WILL AFFECT
THE SRN ZONES MAINLY DURING THE AFTERNOON/EARLY EVENING. GIVEN THE SSW
850-700MB FLOW...THE SEABREEZE SHOULD NOT PUSH AS FAR N ACROSS E TX/NW
LA AS IT HAS IN RECENT DAYS...BUT THE HRRR AND GFS SUGGEST THAT THE
CONVECTION COULD PUSH FARTHER NNE ACROSS THE ERN SECTIONS OF NCNTRL
LA. FOR THAT REASON...HAVE EXTENDED SLIGHT CHANCE POPS FARTHER N INTO
LINCOLN/UNION/OUACHITA PARISHES THIS AFTERNOON/EVENING...BUT A
STABILIZING BNDRY LYR FROM THE LOSS OF HEATING RESULTS IN THE QUICK
DISSIPATION OF THE CONVECTION. DID ALSO INCLUDE LOW CHANCE POPS FOR
THE SE SECTIONS OF NCNTRL LA...WHERE EXTRAPOLATION OF THE CURRENT
CONVECTION WILL LIKELY RESULT IN ADDITIONAL OUTFLOW BNDRYS THAT WILL
FOCUS MORE SCT DEVELOPMENT ESPECIALLY WHEN PEAK HEATING IS REACHED.
WITH THE AC SHIELD GRADUALLY THINNING BY AFTERNOON...AND THE MORNING
LOW STRATUS QUICKLY LIFTING THIS MORNING...MAX TEMPS TODAY SHOULD BE
NEAR IF NOT SLIGHTLY WARMER THAN WHAT WAS OBSERVED WEDNESDAY.
THE HEAT IS ON FRIDAY THROUGH EARLY NEXT WEEK AS THE CENTER OF THE
UPPER RIDGE RESIDES IN VC OF OUR REGION OVER LOWER MS VALLEY. THIS
SHOULD RESULT IN MAX TEMPS CLIMBING INTO THE UPPER 90S AREAWIDE BY THE
WEEKEND...WITH A FEW TRIPLE DIGIT TEMPS NOT OUT OF THE QUESTION OVER
PORTIONS OF THE REGION. EVEN WITH THE 700MB RIDGE CENTERED OVER ERN AR
SUNDAY...AMPLE SOIL MOISTURE OVER ERN LA/SE AR SHOULD HELP MAINTAIN
TEMPS BELOW THE CENTURY MARK...BUT RESULT IN HIGHER DEWPOINTS/HEAT
INDICES SUCH THAT A HEAT ADVISORY MAY BE NEEDED FOR PORTIONS OF NCNTRL
LA/S AR THIS WEEKEND. HAVE TRENDED SLIGHTLY COOLER THAN MAVMOS THIS
WEEKEND...ESPECIALLY GIVEN ITS WARM BIAS FOR THE LAST SEVERAL WEEKS.
THE PROGS CONTINUE TO SHIFT THE UPPER RIDGE CENTER FARTHER NE INTO THE
MID MS VALLEY BY MONDAY WITH THE RIDGE AMPLIFYING INTO THE GREAT LAKES
REGION...WITH THE EXTREME HEAT BEGINNING TO WEAKEN ITS GRIP ON OUR
AREA. BUT THIS WILL BE GRADUAL...UNTIL WEAKNESSES BENEATH THE RIDGE
CENTER ARE ABLE TO MIGRATE W ACROSS MS/SE LA MONDAY...WHICH MAY TOUCH
OFF ISOLATED CONVECTION OVER MUCH OF NCNTRL LA/DEEP E TX. WITH THESE
WEAKNESSES NUDGING CLOSER TO OUR REGION BY TUESDAY...MORE IN THE WAY
OF SCT CONVECTION IS EXPECTED OVER NCNTRL LA/DEEP E TX...WITH ISOLATED
CONVECTION POSSIBLE FARTHER W. FORECAST CONFIDENCE DIMINISHES
THEREAFTER...WITH THE GFS SUGGESTING AN UPPER TROUGH QUICKLY SHIFTING
E ACROSS THE PLAINS WEDNESDAY AND ACROSS THE SRN PLAINS/LOWER MS
VALLEY THURSDAY. MEANWHILE...THE ECMWF REMAINS STOUT WITH THE RIDGE
CENTER ACTUALLY RETROGRADING W BACK ACROSS THE CNTRL CONUS...WITH A
MUCH SLOWER AND WEAKER TROUGH PASSAGE /IF ANY AT ALL/ BY NEXT WEEKEND.
FOR NOW...HAVE MAINTAINED SLIGHT CHANCE POPS THROUGHOUT THE REMAINDER
OF THE EXTENDED...WHILE KEEPING NEAR NORMAL TEMPS THROUGH THE PERIOD.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 96 74 97 74 98 / 10 10 0 0 0
MLU 94 73 96 73 97 / 20 20 0 0 0
DEQ 94 72 95 72 96 / 0 0 0 0 0
TXK 95 74 96 74 97 / 0 0 0 0 0
ELD 94 72 96 73 97 / 10 10 0 0 0
TYR 97 75 97 75 97 / 10 10 0 0 0
GGG 95 74 96 74 97 / 10 10 0 0 0
LFK 96 74 97 74 97 / 20 10 0 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
09
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
239 PM EDT THU AUG 21 2014
.SYNOPSIS...
A STATIONARY FRONT WILL WAVER ACROSS THE MID ATLANTIC AS RIPPLES
OF LOW PRESSURE MOVE ALONG THE BOUNDARY. AN WILL TRAVERSE THE FRONT
FRIDAY NIGHT...WHICH WILL PUSH IT SOUTH AS A COLD FRONT. HIGH
PRESSURE FROM NEW ENGLAND WILL DOWN DOWN THE EAST COAST THIS
WEEKEND.
&&
.NEAR TERM /TONIGHT/...
ISOLD TSTMS HV ALREADY DVLPD IN THE WRN PART OF THE FCST AREA IN
THE SUMMERTIME AIR MASS. MAIN AREA OF PCPN HAS SPENT THE DAY
TRAVERSING ACROSS IN INTO SRN OH ALONG A WARM FNT. THIS WL LKLY
MOVE INTO THE WRN SXN OF THE CWA IN THE 4-5 PM TIMEFRAME...MOVG E
OF THE MTNS THIS EVE. QUSTN WL BE IF IT CAN HOLD TOGETHER - IT
ISN`T TOO IMPRESSIVE ATTM AND HRRR IS EVEN LESS SO AS IT TRIES TO
MOVE TOWARDS THE METROS AFTR 00Z. REGARDING SVR THREAT - PULSE SVR
WOULD BE WORST CASE SCENARIO.
FOG LOOKS TO BE OF LESSER CONCERN TNGT THAN LAST NGT.
LOWS IN THE 60S W OF I-95...L70S E.
&&
.SHORT TERM /FRIDAY/...
BNDRY RMNG IN THE AREA FRIDAY WL MOST LKLY SERVE AS A FOCUS FOR
TSTMS. WL KEEP POPS IN CHC RANGE. AGN SVR THREAT LOOKS LOW - LO
LVL WIND FIELD IS WEAK...CAPE IS NOT OVERLY IMPRESSIVE. FFG IS
RLTVLY HIGH.
HIGHS IN THE MU80S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
AN UPPER LEVEL VORTICITY MAX WILL DIP THROUGH THE AREA OVERNIGHT
FRIDAY...BRINGING ANOTHER BOUT OF ENHANCED RAINFALL. SURFACE HIGH
PRESSURE CENTERED OVER NEW ENGLAND WILL RIDGE DOWN THE EAST COAST AS
AN UPPER LEVEL SUBTROPICAL RIDGE BUILDS OVER THE EASTERN US. THE
SURFACE RIDGE BUILDING DOWN INTO THE AREA WILL WORK WITH LOW
PRESSURE OFF OF THE CAROLINA COAST TO BRING ONSHORE FLOW INTO THE
MID-ATLANTIC BEGINNING SATURDAY MORNING. THE PRIMARY EFFECTS OF THE
INCOMING MARINE AIRMASS WILL BE SEASONABLY COOL TEMPERATURES AND
MOSTLY CLOUDY TO OVERCAST SKIES. EXPECT HIGHS ON SATURDAY...SUNDAY
AND MONDAY TO ONLY BE IN THE MID TO UPPER 70S.
HIGH PRESSURE WILL MOVE MORE OVERHEAD BY MONDAY NIGHT AND ONSHORE
FLOW WILL MOSTLY BE SHUT OFF. LIGHT SOUTHERLY FLOW WILL BEGIN TO
FILL INTO THE AREA TUESDAY...LEADING TO AN TREND TOWARD MORE
SEASONABLE TEMPERATURES BY THE MIDDLE OF THE WEEK WITH HIGHS NEAR 80
ON TUESDAY AND IN THE MID 80S WEDNESDAY AND THURSDAY. HOWEVER...WITH A
RATHER DRY PROFILE CONVECTION IS UNLIKELY TUESDAY OR WEDNESDAY. THE
NEXT THREAT FOR STORMS ACROSS THE AREA SHOULD BE THURSDAY AS A COLD
FRONT APPROACHES THE AREA.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR CONDS XPCTD OUTSIDE OF ANY TSTMS. FOG MAY DVLP AT IAD/CHO/MRB
AFTR MDNGT...BUT NOT XPCTD TO BE AS DENSE AS IT WAS THIS MRNG.
TSTMS AGN PSBL FRI AFTN.
PERIODS OF LOW CEILINGS ARE POSSIBLE AS AN UPPER LEVEL VORT MAX
CROSSES THE AREA FRIDAY NIGHT AND THEN AGAIN OVER THE WEEKEND AND
INTO EARLY NEXT WEEK AS A MARINE AIRMASS SETTLES INTO THE AREA.
&&
.MARINE...
WINDS XPCTD TO RMN BLO SCA VALUES TNGT/FRI. RW/TRW MAY OCCUR ON
THE WATERS THIS EVE AND AGN FRI AFTN.
A SMALL CRAFT ADVISORY MAY BE NECESSARY FOR THE WIDEST ZONES OF THE
LOWER MARYLAND CHESAPEAKE BAY AND THE LOWER TIDAL POTOMAC SATURDAY
AFTERNOON THROUGH SUNDAY NIGHT IN BREEZY EASTERLY FLOW.
&&
.TIDES/COASTAL FLOODING...
WATER LVLS ABOUT 3/4 FT ABV ASTRO NORMS. FRI MRNG TIDE WL BE
HIGH...BUT AM NOT ANTICIPATING REACHING CRITERIA ATTM. HOWEVER...
WE ARE WORKING ON A MARGIN OF INCHES. LATER SHIFTS WL MONITOR THE
SITUATION.
THERE COULD BE MORE NUISANCE ISSUES THIS WKND.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
PRODUCTS...WOODY!/CEB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
227 PM EDT THU AUG 21 2014
.SYNOPSIS...
UNSETTLED WEATHER WILL CONTINUE THROUGH THE WEEKEND WITH
OCCASIONAL SHOWERS AND THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS AND THUNDERSTORMS SUPPORTED BY UPPER LEVEL WAVE IS NOW
MOVING ACROSS THE UPPER OHIO VALLEY. ADDED LIKELY POPS TO THE
NORTH AS UPPER WAVE PASSES THROUGH IN THE AFTERNOON WITH COVERAGE
OF CONVECTION EXPECTED TO INCREASE. VISIBLE SATELLITE IMAGERY
SHOWS AMPLE CLOUD COVERAGE ACROSS PITTSBURGH AND SOUTH. HENCE...OPTIMAL
DAYTIME HEATING WILL NOT OCCUR IN THAT REGION...HOWEVER...INCREASING
MOISTURE WILL AID IN INSTABILITY YIELDING SHOWERS AND
THUNDERSTORMS. TO THE NORTH...SUFFICIENT HEATING DUE TO LESS
CLOUDS HAVE RAMPED UP INSTABILITY. RAP ANALYSIS SHOWS RELATIVELY
STRONGER SHEAR IN THIS ZONE AS WELL. THEREFORE...ISOLATED STRONG
TO MARGINALLY SEVERE STORMS ARE POSSIBLE THIS AFTERNOON NORTH OF
PITTSBURGH.
GREATER COVERAGE OF CONVECTION IS EXPECTED TO WANE LATER IN THE
EVENING DUE TO LOSS OF HEATING. SOME SHOWERS MAY STILL LINGER
ACROSS THE AREA OVERNIGHT DUE TO THE NEARLY STATIONARY SURFACE
BOUNDARY.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
AS THE NEXT SHORTWAVE CROSSES THE REGION FROM A WEAKENING AND
EXITING UPPER LOW...AXIS OF HEAVY RAINFALL WILL SHIFT EAST ON
FRIDAY AS THE BOUNDARY BEGINS TO SLOWLY MOVE. UNCERTAINTY STILL
EXISTS FOR ANY FLOODING AS MODELS ARE IN MINOR DISAGREEMENT FOR
THE PLACEMENT OF HEAVY RAIN. USED MODEL BLEND OF GFS/NAM FOR POPS
AND HPC FOR QPF.
UPPER LEVEL RIDGE DEVELOPS THROUGH THE WEEKEND BRINGING SLIGHTLY
WARMER THAN NORMAL TEMPERATURES. A FEW SHORTWAVES TOPPING THE RIDGE
BRINGS THE CHANCE OF SHOWERS AND THUNDERSTORMS...AT LEAST FOR
SATURDAY BUT OVERALL COVERAGE SHOULD BE SMALL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
MORE CLARITY EXISTS IN THE EXTENDED FORECAST WITH THE LATEST ROUND
OF MODEL GUIDANCE. UPPER RIDGE BUILDING NORTH WILL WORK TO DEFLECT
AN ADVANCING LOW PRESSURE SYSTEM WELL NORTH OF THE GREAT LAKES EARLY
NEXT WEEK...RESULTING IN A WARMING AND DRYING TREND. TEMPERATURES
SHOULD REMAIN AT OR EVEN JUST ABOVE AVERAGE INTO THE MIDDLE OF NEXT
WEEK. LOOKING A LITTLE FARTHER OUT IN TIME THAN USUAL...NO EFFECTS
ARE EXPECTED LOCALLY FROM ANYTHING THAT MAY DEVELOP IN THE TROPICS.
TAX/TG
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
ALTHOUGH STRATIFORM RAIN THIS AFTERNOON/EVENING IS EXPECTED TO
PRIMARILY AFFECT ZZV...HLG...AND MGW...SCATTERED PRECIPITATION IS
EXPECTED AT THE REST OF TAF SITES. A SECONDARY AXIS OF PRECIPITATION
SEEMS TO BE DEVELOPING ALONG THE INTERSTATE 80 CORRIDOR...AND
PRECIPITATION HAS BEEN ADDED TO FKL/DUJ TAFS AS WELL. IFR CONDITIONS
WILL BE POSSIBLE IN ANY THUNDERSTORM...BUT DID NOT WANT TO BLANKET
ALL SITES WITH THAT IN PREVAILING CONDITIONS. SHOWERS SHOULD
DIMINISH IN COVERAGE OVERNIGHT...ALTHOUGH MODELS ARE SUGGESTING
ANOTHER ROUND OF RAIN AFTER MIDNIGHT. HAVE CONTINUED WITH PREVAILING
PRECIPITATION LATE TONIGHT INTO FRIDAY MORNING AT MANY SOUTHERN
TERMINALS. ANY RESTRICTIONS OVERNIGHT WILL BE HIGHLY DEPENDENT ON
PLACEMENT AND AMOUNT OF RAINFALL TODAY.
OUTLOOK.../FRIDAY THROUGH TUESDAY/...
SEVERAL CROSSING DISTURBANCES WILL CAUSE PERIODIC RESTRICTIONS INTO
THE WEEKEND...WITH VFR CONDITIONS EXPECTED MONDAY AND TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
225 PM EDT THU AUG 21 2014
.SYNOPSIS...
UNSETTLED WEATHER WILL CONTINUE THROUGH THE WEEKEND WITH
OCCASIONAL SHOWERS AND THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS AND THUNDERSTORMS SUPPORTED BY UPPER LEVEL WAVE IS NOW
MOVING ACROSS THE UPPER OHIO VALLEY. ADDED LIKELY POPS TO THE
NORTH AS UPPER WAVE PASSES THROUGH IN THE AFTERNOON WITH COVERAGE
OF CONVECTION EXPECTED TO INCREASE. VISIBLE SATELLITE IMAGERY
SHOWS AMPLE CLOUD COVERAGE ACROSS PITTSBURGH AND SOUTH. HENCE...OPTIMAL
DAYTIME HEATING WILL NOT OCCUR IN THAT REGION...HOWEVER...INCREASING
MOISTURE WILL AID IN INSTABILITY YIELDING SHOWERS AND
THUNDERSTORMS. TO THE NORTH...SUFFICIENT HEATING DUE TO LESS
CLOUDS HAVE RAMPED UP INSTABILITY. RAP ANALYSIS SHOWS RELATIVELY
STRONGER SHEAR IN THIS ZONE AS WELL. THEREFORE...ISOLATED STRONG
TO MARGINALLY SEVERE STORMS ARE POSSIBLE THIS AFTERNOON NORTH OF
PITTSBURGH.
GREATER COVERAGE OF CONVECTION IS EXPECTED TO WANE LATER IN THE
EVENING DUE TO LOSS OF HEATING. SOME SHOWERS MAY STILL LINGER
ACROSS THE AREA OVERNIGHT DUE TO THE NEARLY STATIONARY SURFACE
BOUNDARY.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS THE NEXT SHORTWAVE CROSSES THE REGION FROM A WEAKENING AND
EXITING UPPER LOW...AXIS OF HEAVY RAINFALL WILL SHIFT EAST ON
FRIDAY AS THE BOUNDARY BEGINS TO SLOWLY MOVE. UNCERTAINTY STILL
EXISTS FOR ANY FLOODING AS MODELS ARE IN MINOR DISAGREEMENT FOR
THE PLACEMENT OF HEAVY RAIN. USED MODEL BLEND OF GFS/NAM FOR POPS
AND HPC FOR QPF.
UPPER LEVEL RIDGE DEVELOPS THROUGH THE WEEKEND BRINGING SLIGHTLY
WARMER THAN NORMAL TEMPERATURES. A FEW SHORTWAVES TOPPING THE RIDGE
BRINGS THE CHANCE OF SHOWERS AND THUNDERSTORMS...AT LEAST FOR
SATURDAY BUT OVERALL COVERAGE SHOULD BE SMALL.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
MORE CLARITY EXISTS IN THE EXTENDED FORECAST WITH THE LATEST ROUND
OF MODEL GUIDANCE. BY SUN THE SFC LOW FROM THE EARLY WEEKEND DEEPENS
OVER THE PIEDMONT OF VA/NC PULLING THE DEEPER MOISTURE SOUTH WITH
IT. IN THE MEANTIME...THE UPPER RIDGE CURRENTLY SETTING UP OVER THE
SRN MS VALLEY WILL BUILD NORTH FURTHER WITH ITS AXIS SHIFTING EAST
THROUGH SUN. THIS WILL WORK TO DEFLECT AN ADVANCING LOW PRESSURE
SYSTEM WELL NORTH OF THE GREAT LAKES EARLY NEXT WEEK...RESULTING IN
A WARMING AND DRYING TREND. TEMPERATURES SHOULD REMAIN AT OR EVEN
JUST ABOVE AVERAGE INTO THE MIDDLE OF NEXT WEEK.
TAX
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
STILL LOOKING AT THE BEST PRECIP CHANCES ACROSS NORTHERN WEST
VIRGINIA AND SOUTHEAST OHIO THIS AFTERNOON...LESS TO THE NORTH.
KEPT PREVAILING SHRA AT ZZV/MGW AND HAVE ONLY VCTS MENTIONED TO
THE NORTH. IFR POSSIBLE IN ANY THUNDERSTORM. SHOULD SEE A DECREASE
IN COVERAGE WITH LOSS OF HEATING DURING THE EVENING. PUT IN MVFR
FOG AT SOME LOCATIONS LATE. WILL NEED TO WATCH EASTERN OHIO LATE
TONIGHT FOR POSSIBLE INTRUSION OF MCS. ZZV WOULD HAVE THE BEST
CHANCE OF BEING AFFECTED.
OUTLOOK.../FRIDAY THROUGH MONDAY/...
SEVERAL CROSSING DISTURBANCES WILL CAUSE PERIODIC RESTRICTIONS
INTO THE WEEKEND.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
153 PM EDT THU AUG 21 2014
.SYNOPSIS...
THE POTENT UPPER LEVEL STORM SYSTEM CONTINUES TO SIT OVER THE
REGION. THIS SYSTEM WILL SUPPORT THE CHANCE FOR ADDITIONAL SHOWERS
AND THUNDERSTORMS TODAY AND TONIGHT OVER NEW YORK AND
PENNSYLVANIA. THE UNSETTLED WEATHER PATTERN WILL SLOWLY IMPROVE BY
SATURDAY AS HIGH PRESSURE RETURNS TO THE REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
1050 AM UPDATE...
H5 LOW IS SPINNING OVR GEORGIAN BAY AT THIS TIME. S/WV IS MVG THRU
WRN NY AND HAS SPARKED OFF COMPLEX OF TSTMS ACRS THE FINGER LKS
AND NOW MVG INTO THE MOHAWK VLY. THESE STORMS HV DVLPD IN 500
MLCAPE AREA AND ARE MVG THUS ONLY GETTING 0.75-1 INCH PER HR AMNTS
OUT OF THE HEAVIEST CELLS.
EXPECT THIS WL LIKELY BE THE CASE THRU THE DAY AS STORMS DVLP THIS
AFTN. THE BULK OF CNY AND ALL OF NEPA ARE NOW IN SEE TEXT FOR SVR
STORMS THIS AFTN. 0-6KM BULK SHEAR VALUES INCRS ACRS ZONES FM THE
SRN TIER AND POINTS SOUTH TO BTWN 25-30KTS. WITH SOME BREAKS IN
CLDS ACRS FINGER LKS AS OF 14Z, INSTABILITIES WL BE ON THE INCRS
THIS AFTN. SFC LOW IS SITTING UP ACRS SRN ONTARIO WITH AN ILL-
DEFINED WMFNT EXTENDING SOUTH THRU CNTRL NY. LATEST HRRR IS NOW
SUGGESTING AREA OF STORMS MVG ACRS NRN ZONES WL BE PULLING INTO
ERN ZONES AND OUT OF CWA BY 20Z AS S/WV MVS OFF TO THE EAST.
HWVR, ATMOS WL RMN UNSTABLE THRU MOST OF THE DAY TDA AND WITH ANY
BNDRYS LURKING WL LKLY SEE DVLPMNT, THO NOT ENUF TO WARRANT LKLY
POPS AND WL REDUCE POPS DOWN TO HICHC AT BEST. NO OTHER CHGS
NEEDED TO GRIDS. WL CONTINUE THE MENTION OF LOCALLY HVY RAINFALL
IN HWO WITH PW VALUES 1-2 SD ABV NORMAL.
PREV DISCO BLO...
650 AM EDT UPDATE...
MOSTLY CLOUDY SKIES ARE PRESENT THIS MORNING ACROSS PORTIONS OF
CENTRAL NY AND NORTHEAST PA. PATCHY FOG HAVE DEVELOP ALONG THE
VALLEYS. EXPECT FOG TO LIFT WITHIN THE NEXT COUPLE OF HOURS.
SHOWERS HAVE ALSO DEVELOPED ACROSS WESTERN NY AND PA. EXPECT THESE
TO DRIFT TO THE EAST AROUND 15-20 MPH. MADE MINOR ADJUSTMENTS TO
THE PREVIOUS FORECAST. FOR MORE INFORMATION ON TODAY`S EVENT...
PLEASE READ DISCUSSION BELOW.
PREVIOUS FORECAST...
430 AM EDT UPDATE...
SHOWERS THIS MORNING HAVE PRETTY MUCH TAPERED OFF AND JUST AN
ISOLATED LIGHTNING STRIKE HERE ARE STILL GOING. PATCHY VALLEY FOG
HAVE ALSO DEVELOPED THIS MORNING AND EXPECT THIS TO MIX OUT
SHORTLY AFTER SUNRISE.
THE UPPR LEVEL LOW LOCATED OVER THE CENTRAL GREAT LAKES REGION
THAT HAVE BROUGHT US SHOWERS YESTERDAY WILL SLIGHTLY WEAKEN TODAY
AND DRIFT SLOWLY TOWARDS NY. AS THIS LOW DRIFTS TO THE SOUTH IT
WILL EJECT A VORTICITY MAXIMA ACROSS PORTIONS OF CENTRAL NY AND
NORTHEAST PA. THIS LOOKS LIKE IT WILL TRIGGER SHOWERS AND
THUNDERSTORMS ACROSS THE ARE LATE THIS MORNING/AFTERNOON.
ACTIVITY THAT DOES DEVELOPS TODAY WILL HAVE MORE INSTABILITY TO
WORK WITH THAN YESTERDAY. GUIDANCE IS INDICATING SBCAPE VALUES AROUND
2500 J/KG... BELIEVE THIS MAY BE A LITTLE HIGH BUT VALUES AROUND
1000 J/KG AREN`T TOO UNREASONABLE. 0-6KM BULK SHEAR VALUES ARE
EXPECTED TO BE AROUND 20 KNOTS OVER CENTRAL NY AND 30 OVER
NORTHEAST PA. A FEW STRONG STORMS MAY DEVELOP TOMORROW... AND ARE
EXPECTED TO BE MAINLY OVER NE PA WHERE THE SHEAR IS A LITTLE
STRONGER. WITH THE MENTIONED STATEMENTS ABOVE... EXPECT TO SEE
MORE CONVECTION OVERALL TODAY THAN PREVIOUS DAYS. THE BEST MID
LVL SUPPORT DURING THE TIME FRAME FOR LATE MORNING/AFTERNOON IS
EXPECTED TO BE I-81 AND EAST. PWAT VALUES TODAY ARE ALSO EXPECTED TO
BE AROUND 1.4 INCHES GIVE OR TAKE. WITH THAT BEING SAID WE COULD
SEE SOME LOCALIZED HEAVY RAINFALL RATES TODAY WITH THE CONVECTION.
TONIGHT THE UPPER LVL TROUGH WILL CONTINUE TO SHIFT EAST. SHOWERS MAY
LINGER THROUGH THE NIGHT AS WE MAY REMAIN UNDER CYCLONIC FLOW TILL
LATE IN THE NIGHT. THE TROUGH AXIS IS EXPECTED TO BE LOCATED OVER
CENTRAL NY BY LATE THURSDAY NIGHT/FRIDAY MORNING. DEPENDING ON HOW
QUICKLY THE AXIS MOVES EAST WILL DEPEND ON HOW LONG SHOWERS MAY
LINGER.
TEMPS ARE EXPECTED TO RISE INTO THE 70S AND ISOLATED SPOTS IN THE
80S THIS AFTERNOON AS 850MB TEMPS REMAIN NEAR 14 DECREES CELSIUS.
TEMPS TONIGHT ARE EXPECTED TO REMAIN IN THE 60S AS DENSE CLOUD
COVERAGE WILL INHIBIT STRONG COOLING.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
430 AM EDT UPDATE...
BY FRIDAY THE UPPR LVL TROUGH WILL BE EAST OF THE AREA AND
THE LARGE RIDGE CURRENTLY CENTERED OVER THE SOUTHERN CONUS WILL
MOVE EAST AND BECOME SLIGHTLY AMPLIFIED OVER THE MID-WEST. THIS
WILL RESULT IN OUR PATTERN ALOFT TRANSITIONING TO A NORTHWESTERLY
FLOW. WEAK SPURTS OF ENERGY WILL SLIDE SOUTH INTO OUR AREA ON
FRIDAY AND DUE TO THE COMBINATIONS OF LINGERING LOW LVL
MOISTURE... WEAK WAVES... AND HEATING FROM THE SUN... SHOWERS AND
THUNDERSTORMS MAY DEVELOP ACROSS THE AREA.
LATE FRIDAY NIGHT/SATURDAY MORNING WEAK VORTICITY MAXES WILL
TRAVEL ALONG THE OUTER EDGE OF THE RIDGE ALOFT AND MAY GENERATE
SOME SHOWERS OVER THE WESTERN CWA. BUT... BY SATURDAY AFTERNOON
THE UPPR RIDGE WILL BE FURTHER EAST AND SUBSIDENCE WILL START TO
TAKE CONTROL OF THE AREA. THIS WILL CREATE AN ENVIRONMENT THAT WILL
EVENTUALLY INHIBIT CONVECTIVE DEVELOPMENT. THUS... BY SATURDAY
EVENING THE CHANCE FOR SHOWERS WILL BE GONE.
TEMPERATURES DURING THIS TIME FRAME WILL RISE INTO THE 70S EACH
AFTERNOON AND FALL INTO THE LOW TO MID 50S EACH MORNING.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
3 AM UPDATE...MEDIUM RANGE MODELS INDICATE A STRONG UPPER LEVEL
RIDGE WILL EXTEND FROM THE GULF STATES NORTH INTO THE LOCAL AREA.
THIS COMBINED WITH SFC HIGH PRES ALONG THE NEW ENGLAND COAST WILL
PROVIDE A PLEASANT STRETCH OF DRY WEATHER WITH TEMPS RUNNING A FEW
DEGREES ABOVE SEASONAL NORMALS. BY LATE WEDNESDAY INTO WEDNESDAY
NIGHT AN UPPER LEVEL TROF AND ASSOCIATED SFC FRONT MAY BRING THE
AREA SOME SHOWERS.
245 PM UPDATE...
WPC GUIDANCE LOOKS FINE FOR THE EXTENDED FORECAST WITH DRY WEATHER
EXPECTED. A LARGE RIDGE OF HIGH PRESSURE ALOFT, WITH 588 DM
HEIGHTS WILL SPREAD INTO THE LOWER GREAT LAKES. SUNDAY THROUGH
EARLY NEXT WEEK WE WILL SEE THE IMPACTS OF THIS RIDGE WITH VERY
QUIET WEATHER. WITH A NORTHERLY TO NORTHEAST FLOW ALOFT AND NEAR
THE SURFACE IT WILL BE COMFORTABLE WITH HIGHS NEAR 80 AND
COMFORTABLE NIGHTS. FARTHER DOWN THE ROAD AS THE RIDGE MOVES EAST,
OUR FLOW ALOFT WILL BECOME MORE SOUTHWESTERLY. EVENTUALLY THIS
SHOULD TRANSLATE INTO MUCH, MUCH WARMER AIR BY THE MIDDLE OF NEXT
WEEK.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
18Z UPDATE...
AN UPPER LEVEL LOW IS MOVING THROUGH THE EASTERN GREAT LAKES THIS
AFTERNOON. A DISTURBANCE ASSOCIATED WITH THE UPPER LOW...AND
DAYTIME HEATING...WILL GENERATE SCATTERED SHOWERS AND
THUNDERSTORMS. WHILE MUCH OF THE TIME WILL BE VFR...MOST TERMINALS
SHOULD BE IMPACTED AT SOME POINT THIS AFTERNOON TO EARLY
EVENING...AND TIMING OF TSRA TEMPO GROUPS IN TAFS HONES INTO MOST
LIKELY PERIOD AS BEST AS POSSIBLE /DEFINITELY SUBJECT TO AMENDING
AS THINGS EVOLVE/. SYR-RME MAY GET MORE CONVECTION...BUT EARLIER
CONVECTION FORCED STABILIZING BOUNDARY TO THE SOUTH AND THUS
ACTUAL CB IS LESS CERTAIN COMPARED TO THE REMAINDER OF THE
TERMINALS. MOISTURE FROM RAINFALL...AND VERY WEAK FLOW/LACK OF
MIXING TONIGHT...WILL LEAD TO MVFR TO IFR DEVELOPMENT
OVERNIGHT...AND LIKELY WORSE THAN THAT FOR KELM WHERE FOG WILL
SHOULD TURN DENSE. AT LEAST MVFR FOR MUCH OF FRIDAY MORNING WITH
SOME GRADUAL IMPROVEMENT BY MIDDAY...YET ALSO NEW SCATTERED SHRA-
TSRA POSSIBLE. VARIABLE OR LIGHT SW WIND THIS AFTERNOON...BECOMING
LIGHT- VARIABLE TO CALM TONIGHT. LIGHT SE TO S FRIDAY.
OUTLOOK...
FRI THROUGH FRI NGT...BRIEF RESTRICTIONS POSSIBLE IN SCT SHRA/TSRA FRI
AFTERNOON...THEN IFR FOG/STRATUS DEVELOPMENT POSSIBLE FRIDAY
NIGHT...ESPECIALLY KELM.
SAT THROUGH TUE...VFR EXCEPT RESTRICTIONS POSSIBLE IN EARLY
MORNING FOG...MAINLY KELM.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...KAH
NEAR TERM...KAH/PVN
SHORT TERM...KAH
LONG TERM...HEDEN/RRM
AVIATION...MDP
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 PM EDT THU AUG 21 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES WILL DIVE SOUTHEAST
INTO OUR REGION FROM THE OHIO VALLEY AND MIDWEST. A COLD FRONT
LOCATED ACROSS THE MID ATLANTIC ON FRIDAY WILL MOVE SOUTH THROUGH
THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 310 PM WEDNESDAY...
NORTHWEST FLOW CONTINUES ALOFT. THE PIEDMONT TROUGH IS SET UP OVER
THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE WEST HAVE SEEN
MORE MIXING THAN IN THE EAST WITH MORE WESTERLY FLOW AND DRIER AIR
ALOFT. MLCAPE RANGES FROM LESS THAN 1000 J/KG TO AS MUCH AS 2000
J/KG. THE CUMULUS FIELD OVER THE COASTAL PLAIN IN A BIT MORE
PRONOUNCED WHERE LOW-LEVEL CONVERGENCE AND INSTABILITY OVERLAP. TO
THE NORTHWEST...A SERIES OF UPPER DISTURBANCES ARE MOVING ACROSS
KENTUCKY/WEST VIRGINIA. THE MEAN FLOW MAY CAUSE SOME OF THE
SCATTERED CONVECTION THAT TRIGGERS FROM THIS DISTURBANCE TO MOVE
SOUTHEAST INTO THE NORTHWEST OR NORTHERN PIEDMONT BY THIS EVENING.
HOWEVER...THE HRRR CONTINUES TO SHOW VERY LITTLE ACTIVITY THIS
AFTERNOON. EFFECTIVE SHEAR WILL INCREASE 25-30KT ACROSS THE NORTH
THIS EVENING...SO IF ANY STORMS CAN GET GOING THERE...THEY WILL
STAND THE BEST CHANCE OF BEING STRONG TO SEVER
WITH THE LOSS OF HEATING...THE CHANCE OF SHOWERS OR STORMS WIL
SLOWLY DIMINISH...THOUGH A CHANCE MAY LINGER ACROSS THE NORTH
THROUGH MIDNIGHT AS CONVECTION OVER VIRGINIA EVOLVES. LOWS IN THE
LOWER 70S.
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 235 PM THURSDAY...
FRIDAY WILL BE ANOTHER DAY WITH NORTHWESTERLY FLOW ALOFT...SURFACE
TROUGHING IN THE EAST...AND THE POTENTIAL FOR A DISTURBANCE OR TWO
TO CROSS THE AREA. THE MAIN DISTURBANCES IN QUESTION ARE LIKELY
ASSOCIATED WITH CONVECTION OVER THE UPPER MIDWEST...AND ARE PROGGED
TO MOVE SOUTHEAST ACROSS THE AREA LATE FRIDAY AFTERNOON. TIMING OF
SUCH A FEATURE IS STILL TOUGH THIS FAR OUT...SO CONFIDENCE IN ITS
ADDITIONAL SUPPORT FOR AFTERNOON CONVECTION IS LOW. DEEP MIXING IS
EXPECTED AGAIN DURING THE AFTERNOON...WHICH WILL TEMPER INSTABILITY
A LITTLE IN THE WEST WHERE DEWPOINTS SHOULD DROP BACK INTO THE MID
60S. THERMAL PROFILES ARE RELATIVELY SIMILAR TO TODAY...SO MLCAPE
SHOULD AGAIN RANGE FROM LESS THAN 1000 J/KG IN THE WEST TO OVER 1500
J/KG IN THE EAST. A BELT OF STRONGER WESTERLIES OVER THE CENTRAL
APPALACHIANS WILL LIKELY ENHANCE CONVECTION OVER VA...AND SOME OF
THIS ACTIVITY MAY DRIFT SOUTH INTO THE NORTHERN PORTIONS OF THE CWA
BY FRIDAY EVENING...SO WILL HAVE THE HIGHEST CHANCE POPS ACROSS THE
NORTH...WHILE AREAS IN SOUTHERN PIEDMONT MAY STAY DRY.
H85 TEMPS ARE FORECAST TO BE ABOVE 20C AGAIN FRIDAY AND WITH DEEP
MIXING RESULTS IN MID TO POSSIBLY UPPER 90S. DEWPOINTS ARE FORECAST
TO MIX OUT A LITTLE MORE IN THE EAST THAN TODAY...THOUGH ONLY
SLIGHTLY...SO HEAT INDEX VALUES SHOULD AGAIN HOLD AROUND 100F IN THE
SOUTHEAST.
DEPENDING ON HOW MUCH CONVECTION THERE IS TO THE NORTH FRIDAY
EVENING...THERE IS THE POTENTIAL FOR A WEAK EFFECTIVE FRONT INTO THE
NORTHERN COASTAL PLAIN FRIDAY NIGHT...NECESSITATING POPS THROUGH THE
OVERNIGHT HOURS. LOWS IN THE UPPER 60S TO LOWER 70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 145 PM THURSDAY...
THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE
ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF
THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS
CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE
SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED
OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE
BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE
BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT
WITHIN THE NORTHWEST FLOW.
THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO
SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST
OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL
SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP
CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY.
LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT
WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN
ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE
RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN
BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY
FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY.
TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER
RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S
TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE
REMAINDER OF THE WEEK.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 200 PM THURSDAY...
VFR CONDITIONS ACROSS CENTRAL NC THIS AFTERNOON WITH A GENERALLY
LIGHT WESTERLY WIND. A COUPLE WEAK DISTURBANCES WITHIN THE
NORTHWESTERLY FLOW ALOFT WILL CROSS THE APPALACHIANS THIS
EVENING...BUT THERE IS RELATIVELY LOW CONFIDENCE IN WHETHER OR NOT
ADDITIONAL SHOWERS AND STORMS WILL BE ABLE TO MOVE EAST INTO THE
PIEDMONT THIS AFTERNOON. TO THE EAST...WHERE INSTABILITY IS
GREATEST...SOME WEAK CONVERGENCE MAY SUPPORT STORMS OVER THE COASTAL
PLAIN...MOSTLY FROM KFAY TO KRWI AND EAST. HOWEVER...CONFIDENCE IS
TOO LOW FOR MENTION IN THE CURRENT TAF.
MOST OF ANY CONVECTION WILL DIE DOWN AFTER SUNSET...THOUGH MODELS
SHOW THE POTENTIAL FOR SOME ADDITIONAL STORMS MOVING THROUGH SOUTHERN
VA TO TRACK INTO THE NORTHERN COASTAL PLAIN OVERNIGHT. FOG AND
STRATUS SHOULD AGAIN BE ISOLATED AND MOSTLY MVFR.
OUTLOOK... A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE
WEEKEND...BRINGING A PERIOD OF UNSETTLED WEATHER AND ADVERSE
AVIATION CONDITIONS. DRIER WEATHER IS EXPECTED NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...BLS
SHORT TERM...BLS
LONG TERM...MLM
AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
235 PM EDT THU AUG 21 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES WILL DIVE SOUTHEAST
INTO OUR REGION FROM THE OHIO VALLEY AND MIDWEST. A COLD FRONT
LOCATED ACROSS THE MID ATLANTIC ON FRIDAY WILL MOVE SOUTH THROUGH
THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM WEDNESDAY...
NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY
OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH
IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE
WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY
ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND
DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER
DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE
IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE
PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS
CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING
AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS
BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER
EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL
BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST
OF US 1.
OVERNIGHT LOWS IN THE LOWER 70S.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 235 PM THURSDAY...
FRIDAY WILL BE ANOTHER DAY WITH NORTHWESTERLY FLOW ALOFT...SURFACE
TROUGHING IN THE EAST...AND THE POTENTIAL FOR A DISTURBANCE OR TWO
TO CROSS THE AREA. THE MAIN DISTURBANCES IN QUESTION ARE LIKELY
ASSOCIATED WITH CONVECTION OVER THE UPPER MIDWEST...AND ARE PROGGED
TO MOVE SOUTHEAST ACROSS THE AREA LATE FRIDAY AFTERNOON. TIMING OF
SUCH A FEATURE IS STILL TOUGH THIS FAR OUT...SO CONFIDENCE IN ITS
ADDITIONAL SUPPORT FOR AFTERNOON CONVECTION IS LOW. DEEP MIXING IS
EXPECTED AGAIN DURING THE AFTERNOON...WHICH WILL TEMPER INSTABILITY
A LITTLE IN THE WEST WHERE DEWPOINTS SHOULD DROP BACK INTO THE MID
60S. THERMAL PROFILES ARE RELATIVELY SIMILAR TO TODAY...SO MLCAPE
SHOULD AGAIN RANGE FROM LESS THAN 1000 J/KG IN THE WEST TO OVER 1500
J/KG IN THE EAST. A BELT OF STRONGER WESTERLIES OVER THE CENTRAL
APPALACHIANS WILL LIKELY ENHANCE CONVECTION OVER VA...AND SOME OF
THIS ACTIVITY MAY DRIFT SOUTH INTO THE NORTHERN PORTIONS OF THE CWA
BY FRIDAY EVENING...SO WILL HAVE THE HIGHEST CHANCE POPS ACROSS THE
NORTH...WHILE AREAS IN SOUTHERN PIEDMONT MAY STAY DRY.
H85 TEMPS ARE FORECAST TO BE ABOVE 20C AGAIN FRIDAY AND WITH DEEP
MIXING RESULTS IN MID TO POSSIBLY UPPER 90S. DEWPOINTS ARE FORECAST
TO MIX OUT A LITTLE MORE IN THE EAST THAN TODAY...THOUGH ONLY
SLIGHTLY...SO HEAT INDEX VALUES SHOULD AGAIN HOLD AROUND 100F IN THE
SOUTHEAST.
DEPENDING ON HOW MUCH CONVECTION THERE IS TO THE NORTH FRIDAY
EVENING...THERE IS THE POTENTIAL FOR A WEAK EFFECTIVE FRONT INTO THE
NORTHERN COASTAL PLAIN FRIDAY NIGHT...NECESSITATING POPS THROUGH THE
OVERNIGHT HOURS. LOWS IN THE UPPER 60S TO LOWER 70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 145 PM THURSDAY...
THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE
ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF
THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS
CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE
SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED
OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE
BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE
BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT
WITHIN THE NORTHWEST FLOW.
THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO
SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST
OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL
SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP
CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY.
LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT
WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN
ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE
RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN
BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY
FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY.
TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER
RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S
TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE
REMAINDER OF THE WEEK.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 200 PM THURSDAY...
VFR CONDITIONS ACROSS CENTRAL NC THIS AFTERNOON WITH A GENERALLY
LIGHT WESTERLY WIND. A COUPLE WEAK DISTURBANCES WITHIN THE
NORTHWESTERLY FLOW ALOFT WILL CROSS THE APPALACHIANS THIS
EVENING...BUT THERE IS RELATIVELY LOW CONFIDENCE IN WHETHER OR NOT
ADDITIONAL SHOWERS AND STORMS WILL BE ABLE TO MOVE EAST INTO THE
PIEDMONT THIS AFTERNOON. TO THE EAST...WHERE INSTABILITY IS
GREATEST...SOME WEAK CONVERGENCE MAY SUPPORT STORMS OVER THE COASTAL
PLAIN...MOSTLY FROM KFAY TO KRWI AND EAST. HOWEVER...CONFIDENCE IS
TOO LOW FOR MENTION IN THE CURRENT TAF.
MOST OF ANY CONVECTION WILL DIE DOWN AFTER SUNSET...THOUGH MODELS
SHOW THE POTENTIAL FOR SOME ADDITIONAL STORMS MOVING THROUGH SOUTHERN
VA TO TRACK INTO THE NORTHERN COASTAL PLAIN OVERNIGHT. FOG AND
STRATUS SHOULD AGAIN BE ISOLATED AND MOSTLY MVFR.
OUTLOOK... A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE
WEEKEND...BRINGING A PERIOD OF UNSETTLED WEATHER AND ADVERSE
AVIATION CONDITIONS. DRIER WEATHER IS EXPECTED NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...CBL/BLS
SHORT TERM...BLS
LONG TERM...MLM
AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
200 PM EDT THU AUG 21 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW
ALOFT WILL CROSS THE REGION THROUGH LATE WEEK. A BACK DOOR COLD
FRONT WILL MOVE SOUTH OF THE AREA ON SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM WEDNESDAY...
NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY
OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH
IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE
WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY
ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND
DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER
DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE
IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE
PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS
CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING
AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS
BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER
EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL
BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST
OF US 1.
OVERNIGHT LOWS IN THE LOWER 70S.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 320 AM THURSDAY...
UPPER RIDGE OVER THE CENTRAL US CONTINUES TO AMPLIFY AS THE UPPER
TROUGH MOVES OFF THE MID-ATLANTIC COAST. WHILE THERE CONTINUES TO
BE CONSIDERABLE RUN-TO-RUN VARIABILITY WITH HOW NWP GUIDANCE HANDLE
INDIVIDUAL SHORTWAVES EMBEDDED IN THE MEAN TROUGH...THE OVERRIDING
THEME OVER THE LAST SEVERAL DAYS HAS BEEN RATHER CONSISTENT IN
SHOWING AN INCREASE/UPTICK IN RAIN CHANCES/POPS LATE FRIDAY AND INTO FRIDAY
NIGHT IN RESPONSE TO THE BROADER SYNOPTIC SCALE ASCENT MOVING DOWN
THE MID-ATLANTIC COAST AND ATTENDANT BACK-DOOR FRONTAL INTO THE
AREA. WILL MAINTAIN CURRENT POP CONFIGURATION WITH HIGH CHANCE POPS
ACROSS THE NORTH INVOF OF THE BETTER FORCING AND LOW CHANCE POPS
SOUTH.
A TOUCH COOLER ON FRIDAY AS HEIGHTS LOWER ALOFT COMBINED WITH AN
INCREASE IN CLOUD COVER AND RAIN CHANCES. HIGHS IN THE LOWER 90S
NORTH TO MID 90S SOUTH. LOWS FRIDAY NIGHT IN THE UPPER 60S TO LOWER
70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 145 PM THURSDAY...
THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE
ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF
THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS
CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE
SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED
OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE
BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE
BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT
WITHIN THE NORTHWEST FLOW.
THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO
SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST
OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL
SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP
CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY.
LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT
WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN
ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE
RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN
BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY
FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY.
TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER
RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S
TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE
REMAINDER OF THE WEEK.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 200 PM THURSDAY...
VFR CONDITIONS ACROSS CENTRAL NC THIS AFTERNOON WITH A GENERALLY
LIGHT WESTERLY WIND. A COUPLE WEAK DISTURBANCES WITHIN THE
NORTHWESTERLY FLOW ALOFT WILL CROSS THE APPALACHIANS THIS
EVENING...BUT THERE IS RELATIVELY LOW CONFIDENCE IN WHETHER OR NOT
ADDITIONAL SHOWERS AND STORMS WILL BE ABLE TO MOVE EAST INTO THE
PIEDMONT THIS AFTERNOON. TO THE EAST...WHERE INSTABILITY IS
GREATEST...SOME WEAK CONVERGENCE MAY SUPPORT STORMS OVER THE COASTAL
PLAIN...MOSTLY FROM KFAY TO KRWI AND EAST. HOWEVER...CONFIDENCE IS
TOO LOW FOR MENTION IN THE CURRENT TAF.
MOST OF ANY CONVECTION WILL DIE DOWN AFTER SUNSET...THOUGH MODELS
SHOW THE POTENTIAL FOR SOME ADDITIONAL STORMS MOVING THROUGH SOUTHERN
VA TO TRACK INTO THE NORTHERN COASTAL PLAIN OVERNIGHT. FOG AND
STRATUS SHOULD AGAIN BE ISOLATED AND MOSTLY MVFR.
OUTLOOK... A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE
WEEKEND...BRINGING A PERIOD OF UNSETTLED WEATHER AND ADVERSE
AVIATION CONDITIONS. DRIER WEATHER IS EXPECTED NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...CBL/BLS
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
145 PM EDT THU AUG 21 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW
ALOFT WILL CROSS THE REGION THROUGH LATE WEEK. A BACK DOOR COLD
FRONT WILL MOVE SOUTH OF THE AREA ON SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM WEDNESDAY...
NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY
OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH
IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE
WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY
ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND
DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER
DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE
IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE
PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS
CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING
AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS
BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER
EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL
BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST
OF US 1.
OVERNIGHT LOWS IN THE LOWER 70S.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 320 AM THURSDAY...
UPPER RIDGE OVER THE CENTRAL US CONTINUES TO AMPLIFY AS THE UPPER
TROUGH MOVES OFF THE MID-ATLANTIC COAST. WHILE THERE CONTINUES TO
BE CONSIDERABLE RUN-TO-RUN VARIABILITY WITH HOW NWP GUIDANCE HANDLE
INDIVIDUAL SHORTWAVES EMBEDDED IN THE MEAN TROUGH...THE OVERRIDING
THEME OVER THE LAST SEVERAL DAYS HAS BEEN RATHER CONSISTENT IN
SHOWING AN INCREASE/UPTICK IN RAIN CHANCES/POPS LATE FRIDAY AND INTO FRIDAY
NIGHT IN RESPONSE TO THE BROADER SYNOPTIC SCALE ASCENT MOVING DOWN
THE MID-ATLANTIC COAST AND ATTENDANT BACK-DOOR FRONTAL INTO THE
AREA. WILL MAINTAIN CURRENT POP CONFIGURATION WITH HIGH CHANCE POPS
ACROSS THE NORTH INVOF OF THE BETTER FORCING AND LOW CHANCE POPS
SOUTH.
A TOUCH COOLER ON FRIDAY AS HEIGHTS LOWER ALOFT COMBINED WITH AN
INCREASE IN CLOUD COVER AND RAIN CHANCES. HIGHS IN THE LOWER 90S
NORTH TO MID 90S SOUTH. LOWS FRIDAY NIGHT IN THE UPPER 60S TO LOWER
70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 145 PM THURSDAY...
THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE
ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF
THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS
CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE
SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED
OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE
BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE
BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT
WITHIN THE NORTHWEST FLOW.
THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO
SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST
OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL
SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP
CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY.
LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT
WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN
ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE
RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN
BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY
FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY.
TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER
RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S
TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE
REMAINDER OF THE WEEK.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 715 AM THURSDAY...
ANY SUB-VFR CONDITIONS WILL AGAIN LIFT TO VFR BY MID TO LATE MORNING
AT THE LATEST... WITH THE PROSPECTS OF VFR CONDITIONS BY 13-15Z AT
ALL TAF SITES. ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS WILL
BE POSSIBLE AGAIN ON THURSDAY ACROSS ALL OF CENTRAL NC. HOWEVER...
THE PROBABILITY AT A GIVEN SITE IS TOO LOW TO INCLUDE IN THE TAFS AT
THIS TIME.
OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS
AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD
FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING
ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...CBL/BLS
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...CBL/BLS