Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 200959
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
559 AM EDT WED AUG 20 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 6 PM THIS EVENING/...
SHORTWAVE ROTATING THRU BASE OF UPPER LOW WILL SWING THRU CENTRAL
PA LATER TODAY...BRINGING NUMEROUS SHRA/TSRA. THE HIGHEST
CONFIDENCE OF RAIN /WITH POPS NR 100 PCT/ WILL COME ARND 12Z OVR
THE NW MTNS IN CONJUNCTION WITH PASSAGE OF ANOMALOUS PWATS AND
BEST LG SCALE FORCING AS IMPLIED BY MDL 500-300MB Q-VEC
CONVERGENCE FIELDS. LATEST RAP/HRRR CONSISTENT IN BRINGING SHOWERS
INTO THE CENTRAL MTNS BY LATE AM/EARLY AFTN. FURTHER EAST...SHOWERS
NOT LIKELY TO OVERSPREAD THE SUSQ VALLEY UNTIL THE AFTN HOURS.

WANING LG SCALE FORCING ANTICIPATED BY AFTN...AS SHORTWAVE LIFTS
TO THE NORTH. HOWEVER...HEATING OF MOIST/UNSTABLE AIR MASS IS
EXPECTED TO RESULT IN MODERATE CAPES BY AFTN ACROSS THE WESTERN
HALF OF THE STATE. NO CAPPING INVERSION IN PLACE...SO EXPECT
NUMEROUS SHRA/TSRA TO DEVELOP AS WE REACH CONVECTIVE TEMP DURING
THE AFTN HOURS. LATEST GEFS DATA AND OPER MDL QPF IMPLY MOST AREAS
WILL SEE MEASURABLE RAINFALL ACROSS CENTRAL PA WITH THE POSSIBLE
EXCEPTION OF THE EXTREME SE COUNTIES.

MDL BLENDED QPF SUGGESTS RAINFALL WILL AVERAGE CLOSE TO 0.25 INCHES
TODAY. HOWEVER...COMBINATION OF HIGH PWAT/CAPES ACROSS THE W MTNS
IMPLY THE POTENTIAL OF MUCH HIGHER AMTS IN THUNDERSTORMS.
CONVECTION-ALLOWING MDLS SUPPORT THIS SCENARIO WITH SPOTS AMTS
ARND 2 INCHES ACROSS THE W MTNS BY LATE TODAY.

ALTHOUGH CLOUDS WILL PREDOMINATE TODAY...ENOUGH BREAKS EXPECTED TO
PUSH READINGS TO NEAR SEASONAL NORMS WITH HIGHS FROM THE M70S OVR
THE HIGH TERRAIN OF THE ALLEGHENIES...TO THE M80S ACROSS THE LOWER
SUSQ VALLEY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
FOCUS OF DWINDLING SHRA/TSRA WILL SHIFT TO THE EASTERN COUNTIES
THIS EVENING ALONG AXIS OF WEAKENING LL JET/PLUME OF HIGHER PWATS.
AFTER A LULL IN THE ACTIVITY THU AM...ANOTHER ROUND OF CONVECTION
IS EXPECTED THURSDAY AFTERNOON AS UPPER TRACKS NORTH OF THE STATE.
STEEP LPS RATES CAUSED BY COOL POOL ALOFT WILL PROMOTE WIDESPREAD
AFTN CONVECTION...ESP ACROSS THE N MTNS. HAVE BUMPED POPS UPWARD
TO THE LIKELY CATEGORY ACROSS MOST OF CENTRAL PA BASED ON LATEST
GEFS/CONSALL. GEFS 925 TEMPS IMPLY ANOTHER DAY OF NEAR SEASONAL
TEMPS WITH HIGHS FROM THE M70S TO M80S.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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-MON 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 ISSUES WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
AN ISOLATED SHOWER WILL BE POSSIBLE THROUGH 1 AM ACROSS SOUTH
CENTRAL PA.

MOST OF THE ACTIVITY IS OVER OH AND MOVING EAST. TOPS WERE
COOLING...BUT NOW STORMS ARE WEAKENING SOME.

MINOR CHANGES MADE ON THE 03Z PACKAGE.

OTHERWISE THE MAIN CONCERN WILL BE MVFR AND IFR CONDITIONS
LATE...GIVEN LIGHT WINDS...MAINLY CLEAR SKIES...AND DEWPOINTS
HIGHER THAN WE HAVE SEEN THEM FOR MUCH OF THE SUMMER SEASON SO
FAR.

EXPECT THINGS TO IMPROVE WED MORNING...BUT THE REMAINS OF
CONVECTION TO THE WEST AND THE UPPER LVL TROUGH MOVING IN
WILL RESULT IN AT LEAST SOME SHOWERS. SOME THUNDERSTORMS
WITH HEAVY RAIN WILL BE POSSIBLE.

NOT A LOT OF CHANGE IN THE PATTERN BEFORE THE WEEKEND IF
THEN.

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...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...MARTIN


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