Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 010018
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
818 PM EDT TUE SEP 30 2014

.SYNOPSIS...
A SLOW MOVING UPPER LOW AND WEAKENING COLD FRONT WILL DROP
SOUTHEAST ACROSS THE REGION TONIGHT...BRINGING A LIKELIHOOD OF
SHOWERS AND THUNDERSTORMS...ESPECIALLY ACROSS THE EASTERN HALF OF
PENN. UNSETTLED CONDITIONS WILL MOVE EAST OF THE REGION LATER
WEDNESDAY...WITH DRY WEATHER EXPECTED THROUGH THE END OF THE WEEK.
A STRONGER COLD FRONT WILL PUSH EAST INTO THE COMMONWEALTH LATE
FRIDAY NIGHT AND SATURDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
SLOW MOVING BROKEN LINE OF THUNDERSTORMS HAS BEEN IMPACTING
MUCH OF CENTRAL PENN AND THE AREA RIGHT ALONG THE ALLEGHENY FRONT
OVER THE PAST SEVERAL HOURS...AS A RESULT OF A REGION OF
ENHANCED/DEEP UVVEL AT THE NOSE OF AN APPROACHING 80 KT
CYCLONICALLY CURVED UPPER JET. THE FORCING ASSOCIATED WITH THIS
JET MAX WILL SLIDE TO THE SUSQ VALLEY AND POINTS EAST AFTER 03Z AS
THE CENTERED OF A 568 DAM 500 MB LOW BECOMES CENTERED NEAR KPIT.

THIS CONVECTION HAS BEGUN TO SLOWLY WEAKEN OVER THE PAST HOUR AS
BOUNDARY LAYER HEATING WANES WITH THE ONSET OF NIGHTFALL.

EXPECT THIS AREA OF CONVECTION TO CONTINUE TO WEAKEN GRADUALLY
THROUGH THE LATE EVENING HOURS AS IT DRIFTS EAST TOWARD THE SUSQ
MAINSTEM.

RAINFALL RATES AND 1-3 HOUR TOTALS HAVE BEEN CONTAMINATED GREATLY
/PERHAPS BY 50 PERCENT OR SE/ BY NUMEROUS  OCCURRENCES OF
PEA...TO DIME- SIZE HAIL IN THE STRONGEST CORES THAT HAVE HAD
TROUBLE PENETRATING THE -20C LEVEL UP AROUND 23 KFT. STILL...SOME
OF THE STORMS HAVE DROPPED 0.50 TO 1.00 INCH OF RAIN IN LESS THAN
AN HOUR.

WILL HAVE TO MONITOR THE REGION NEAR AND TO THE NORTH OF
HARRISBURG /TO KIPT AND KAVP/ OVERNIGHT AS THIS UPPER LOW SLOWLY
PROGRESSES EAST ACROSS SCENT PENN AND MAINTAINS A CONCENTRATED
AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP...LOW TO MID LEVEL
FRONTOGENESIS. A BLEND OF THE LATEST HRRR/S PRECIP...AND THE LOCATION
OF THE BEST FGEN FORCING VIA THE 18Z NAM WILL LEAD US TO INCREASE
POPS TO AT LEAST THE HIGH LIKELY CATEGORY LATE TONIGHT ACROSS MUCH
OF THE CENTRAL AND LOWER SUSQ VALLEY.

THE MAIN THREAT TONIGHT WILL BE AREAS OF 1.00 INCH
RAINFALL...WHILE THE CHC OF HAIL GREATLY DIMINISHES BY 01Z.

AS THE UPPER LOW NEARLY GRINDS TO A HALT ACROSS SCENT PENN
TONIGHT...SCATTERED SHOWERS WILL CONTINUE OVERNIGHT...BUT NOT A
CONTINUOUS OR WIDESPREAD RAIN BY ANY MEANS. LOWS GENERALLY IN THE
50S WILL AVERAGE ABOUT 5-10 DEG ABOVE NORMAL FOR THE LAST DAY OF
SEPTEMBER.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
SLOWLY FILLING UPPER LOW WILL MOVE SLOWLY EASTWARD ACROSS THE
COMMONWEALTH ON WEDNESDAY...BRINGING A STEADY DECLINE IN THE
FORCING FOR THE SCATTERED SHOWERS. IT LOOKS QUITE CLOUDY BUT
MAINLY DRY WITH ONLY SLGT CHC POPS UNDER THE "COOL" CORE ALOFT.

TEMPS ON WED WILL BE COOLER THAN RECENT DAYS. EXPECT HIGHS TO
RANGE FROM THE UPPER 60S NORTH TO THE LOWER 70S SOUTH.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
PROGRESSIVE UPPER LOW/COMPACT TROF AXIS FORECAST TO BE LIFTING NE
INTO NEW ENGLAND AT THE START OF THE PERIOD WILL BE REPLACED BY
A SHORT PERIOD OF RISING HEIGHTS LATE IN THE WEEK. A SECOND...MUCH
STRONGER AND EXPANSIVE UPPER TROF AXIS EXTENDING SWD FROM AN UPPER
LOW ANCHORED OVER NRN ONTARIO IS FORECAST TO SWEEP ACROSS THE
EASTERN U.S. OVER THE WEEKEND.

WARMER WEATHER MAKES A BRIEF RETURN THUR...FRI AND EARLY SAT AS
THE UPPER RIDGE TEMPORARILY REBUILDS....WITH MOST MAXES AND MINS
AT LEAST SEVERAL DEGREES ABOVE CLIMO NORMALS. MAX TEMPS SAT WILL
BE BELOW NORMAL.

THE ARRIVAL OF THE SECOND TROF WILL SUPPORT A STRONG COLD FRONT
WITH DEEPER CONNECTIONS TO THE GOMEX AND THE ATLANTIC
OCEAN...THUS POTENTIAL FOR MORE WIDESPREAD AND HEAVIER
RAINFALL THAN WITH THE FIRST FRONT. PASSAGE OF THE FRONT WILL
ALSO BRING NOTICEABLY COOLER TEMPS TO THE REGION STARTING SATURDAY AFTERNOON
INTO MONDAY.

SEVERAL SHORT WAVES DROPPING INTO THE UPPER TROF / EXPECTED
CYCLONIC FLOW OVER THE REGION WILL KEEP THE WEATHER COOL AND
UNSETTLED INTO EARLY NEXT WEEK.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
SLOW MOVING BROKEN LINE OF THUNDERSTORMS HAS BEEN IMPACTING
MUCH OF CENTRAL PENN OVER THE PAST SEVERAL HOURS...AS A RESULT OF
A REGION OF ENHANCED/DEEP UVVEL AT THE NOSE OF AN APPROACHING 80
KT CYCLONICALLY CURVED UPPER JET. THE FORCING ASSOCIATED WITH THIS
JET MAX WILL SLIDE TO THE SUSQ VALLEY AND POINTS EAST THIS MID EVE
AS THE CENTERED OF A 568 DAM 500 MB LOW BECOMES CENTERED NEAR
KPIT.

THOUGH THIS CONVECTION HAS BEEN OVERALL SLOWLY WEAKENING SINCE
SUNSET...JUST ABOUT EVERY CELL PRODUCING SOME LIGHTNING. THIS
AREA OF CONVECTION SHOULD CONTINUE TO GRADUALLY WEAKEN/DIMINISH
THROUGH THE LATE EVENING HOURS AS IT DRIFTS EAST TOWARD THE SUSQ
MAINSTEM...THOUGH ISOLATED STRONGER CELLS STILL POSS IN VICINITY
OF TERMINALS FROM KSEG TO KMDT-KLNS THROUGH 06Z.

AS THE UPPER LOW NEARLY GRINDS TO A HALT ACROSS SCENT PENN
TONIGHT...SCATTERED SHOWERS WILL LINGER OVERNIGHT. FOG/LOW CLOUDS
WILL DEVELOP AS WELL WITH INCREASED LOW LEVEL MOISTURE ALONG WITH
LIGHT WINDS AND MID CLOUD DECK MOVING OUT. EXPECT IFR FOG/CIGS TO
DEVELOP AFTER 04Z ACROSS THE WEST/CENTRAL AND A BIT LATER AFTER
SHOWER ACTIVITY TAPERS OFF IN THE EAST...WITH IFR LINGERING TO THE
MID MORNING HOURS.

FOG/LOWER CIGS START THE DAY WED...WITH SLOW IMPROVEMENT THROUGH
MID/LATE MORNING BEFORE FINALLY ARRIVING AT VFR CONDITIONS FOR
LATE MORNING AND AFTERNOON. WINDS WILL BE LIGHT.


OUTLOOK...

THU...LOW CIGS LIKELY EARLY...AND COULD PERSIST THRU MUCH OF THE
DAY DUE TO HIGH PRESSURE FUELING A MOIST MARITIME FLOW E OF THE
APPLCHNS.

FRI...SHOWERS AND THUNDERSTORMS LKLY ASSOC WITH A STRONG COLD
FRONT. LLWS LKLY DUE TO STG SLY WINDS AHEAD OF THE COLD FRONT.

SAT...AM SHOWERS ERN AREAS. BREEZY WITH IMPROVING CONDITIONS E OF
THE MTNS. ISOLD SHOWERS AND LOCAL MVFR POSSIBLE OVER N/WRN AREAS.

SUN...NO SIG WX.

&&

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

&&

$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LA CORTE
LONG TERM...GARTNER
AVIATION...RXR


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