Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 240154
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
954 PM EDT WED JUL 23 2014

.SYNOPSIS...
A COLD FRONT WILL PUSH SOUTHEAST OF THE COMMONWEALTH OVERNIGHT.
A REFRESHING...COOLER AND LESS HUMID AIRMASS WILL OVERSPREAD THE
COMMONWEALTH FOR THE END OF THE WEEK INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SFC FRONT PUSHING OUT OF THE LOWER SUSQ RIVER VALLEY AT THIS HOUR
WITH DEEP CONVECTION HAVING PUSHED WELL EAST OF THE AREA. SOME
ISOLATED SEVERE REPORTS WERE RECEIVED BY THE OFFICE ON A HANDFUL
OF WARNINGS THIS EVENING...BASICALLY A LOW END EVENT WITH SLOW
MOVING PULSING CELLS IN WEAK SHEAR AND VERY WARM AIR ALOFT.

DEEP LAYER DRYING TAKES PLACE FROM NORTHWEST TO SOUTHEAST
OVERNIGHT WITH CYCLONICALLY SHEARED FLOW PERSISTING ACROSS THE
EASTERN GREAT LAKES AND NORTHERN MID ATLANTIC. THERE COULD STILL
BE BE A LIGHT SHOWER OR TWO THROUGH LATE THIS EVENING AS A POCKET
OF COOLER AIR ALOFT MOVES THROUGH NY STATE AND BRUSHES THE NRN
TIER INTO THE POCONO PLATEAU REGION. ISOLATED SHOWERS MAY ALSO
BRUSH THE LAUREL HIGHLANDS THROUGH MIDNIGHT. ELSEWHERE SHOULD BE
MAINLY DRY FOR THE REMAINDER OF THIS EVENING WITH VARYING AMOUNTS
OF CLOUDS...AVERAGING OUT MOSTLY CLOUDY.

CONDITIONS DRY OUT OVERNIGHT WITH ANY LINGERING SHOWER ACTIVITY
DROPPING SOUTH OF THE MASON DIXON LINE BY 12Z THU. THE GUIDANCE
TEMPS TONIGHT DO DROP NICELY OVER THE NORTH - BUT WILL TEMPER THAT
FALL DUE TO THE ANTICIPATED LOWER CLOUD DECK THERE. MID 50S SHOULD
BE LOW ENOUGH EXCEPT FOR THE MOST RURAL VALLEYS. THUS...THERE
COULD BE A BIT OF VALLEY FOG TONIGHT...BUT THE AIR IS VERY DRY.
WILL THEREFORE NOT MENTION FOG FOR TONIGHT IN THE GRIDS.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
THURSDAY SEEMS LIKE A GREAT DAY FOR ANY OUTDOOR ACTIVITY WITH ANY
LOW CLOUDS BURNING AWAY IN THE MORNING. HIGHER CLOUDS ALONG THE
SRN BORDER MAY LINGER FOR A BIT LONGER...BUT NOT ENOUGH TO WARRANT
A MOSTLY CLOUDY FCST. DESPITE THE 8H TEMPS AS LOW AS +10C IN THE
MORNING ACROSS THE NORTHERN TIER...EVEN THEY SHOULD WARM BACK INTO
THE LOWER/MID 70S. 80F AND MAYBE A LITTLE WARMER IS EXPECTED IN
THE SOUTH.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
OVERALL SCENARIO REMAINS UNCHANGED IN THE LONG TERM PERIOD AS A
LARGE UPPER RIDGE BUILDING OVER THE FOUR CORNERS REGION IS
FORECAST TO EXPAND NORTH AND EAST INTO THE ROCKIES AND PLAINS
DURING THE PERIOD. DOWNSTREAM...THIS WILL LEAD TO MODERATE TO
STRONG LONG WAVE TROFFING OVER THE EASTERN THIRD OF THE COUNTRY.

UPPER LOW TO THE EAST OF HUDSON BAY WILL BE STRENGTHENED AT TIMES
BY SHORTWAVE ENERGY IN THE STRONGER JET STREAM FLOW ACROSS CANADA.
SOUTHWARD EXTENSION OF THIS LOW/TROF WILL AT TIMES DURING THE
PERIOD STRENGTHENING THE TROFFING ACROSS THE NORTHEASTERN U.S./OUR
REGION. THE TREND OF MEDIUM RANGE MODEL GUIDANCE IS FOR
STRONGER/DEEPER TROFFING DOWNSTREAM ACROSS THE EASTERN
U.S...DEVELOPING AN ALMOST FULL LATITUDE TROF EXTENDING FROM THE
EASTERN CANADA LOW SWD TO FLORIDA. THIS WILL LIKELY SERVE TO
EXPAND AND PROLONG THE CHANCES FOR PCPN THIS WEEKEND.

CONDS WILL BE IMPROVING AT THE START OF THE PERIOD AS COLD FRONT
EXITS. A SECOND...POTENTIALLY STRONGER SYSTEM WILL AFFECT THE
REGION LATE NEXT WEEKEND. THE TREND OF STRONGER TROUGHING
MENTIONED ABOVE HAS LEAD TO SLOWER ARRIVAL AND DEPARTURE OF THE
FRONTAL SYSTEM IN THE DAILY PROGS. THE ECMWF IN LATEST RUN HAS
SLOWED UP THE PROGRESSION OF THIS UPPER LEVEL LOW...WHERE THE GFS
OPERATIONAL AND ENSEMBLES HAVE SPED UP ITS PROGRESSION THROUGH THE
GREAT LAKES REGION. A WARM FRONT WILL BE ON THE DOORSTEP OF PA
SUNDAY...AS THE EC CONTINUES TO SLOW ITS PROGRESSION SO EXPECT THE
WARM FRONT TO MOVE IN CLOSER TO MIDDAY SUNDAY. HAVE THUS ADJUSTED
POPS/TIME.

ASSOCIATED COLD FRONT DOES NOT CROSS THE STATE TIL MONDAY...WHERE
SURPRISINGLY AT THIS POINT...THE EC AND GFS COME CLOSELY IN PHASE.
THIS LARGE UPPER LEVEL LOW COULD BECOME QUASI STATIONARY OVER
SOUTHERN CANADA...GREAT LAKES REGION WHICH COULD LEAD TO A
POTENTIAL PROLONGED PERIOD OF SHOWERS AND THUNDERSTORM THROUGH THE
MIDDLE OF NEXT WEEK.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
PRECIPITATION HAS MOVED OUT OF THE AREA...WITH FRONTAL PASSAGE
SLATED TO MOVE THROUGH THE LOWER SUSQUEHANNA REGION IN THE NEXT
FEW HOURS. FOR LOCAL AIRFIELDS...ALL LOCATIONS VFR AT THIS
TIME...WITH THE EXCEPTION OF A SMALL AREA OF MVFR CIGS AROUND
KIPT.

EXPECTING UPSLOPE MOIST FLOW TO ADVECT LOWER CLOUDS INTO THE
WESTERN AND NORTHWESTERN AREAS OVERNIGHT...WITH AREAS OF MVFR/IFR
CIGS AND VSBYS DEVELOPING OVERNIGHT. ELSEWHERE...ESPECIALLY IN
AREAS THAT RECEIVED RAIN...EXPECT FOG FORMATION OVERNIGHT WITH
WIDESPREAD MVFR CONDITIONS...AND LOCAL IFR CONDITIONS.

HIGH PRESSURE TO PROVIDE GENERALLY VFR CONDITIONS THROUGH
SATURDAY...BEFORE SHRA/TSRA MOVE INTO THE WEST LATER
SATURDAY...WITH THE RISK OF SHRA/TSRA SUN/MON.

OUTLOOK...

FRI...PATCHY AM FOG...OTHERWISE VFR.
SAT...PATCHY AM FOG...OTHERWISE MAINLY VFR. PM TSRA/MVFR POSS W.
SUN...SHRA/TSRA WITH WARM FRONT PASSAGE
MON...MORE WIDESPREAD SHRA/TSRA WITH COLD FRONT PASSAGE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...DANGELO/DEVOIR
NEAR TERM...DANGELO/DEVOIR
SHORT TERM...DANGELO/DEVOIR
LONG TERM...LAMBERT/GARTNER
AVIATION...JUNG


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