Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 300425
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1225 AM EDT TUE SEP 30 2014

.SYNOPSIS...
A WEAK COLD FRONT AND AN UPPER LEVEL DISTURBANCE WILL MOVE OUT OF
THE GREAT LAKES AND BRING AN INCREASE IN CLOUDS ALONG WITH SOME
SHOWERS OR THUNDERSTORMS TUESDAY INTO WEDNESDAY. A STRONGER COLD
FRONT WILL PUSH EAST INTO THE COMMONWEALTH LATE FRIDAY NIGHT OR
SATURDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A LONE SHOWER COULD AFFECT A FEW SPOTS ALONG THE MASON DIXON LINE
IN YORK AND ADAMS CO BTWN 04Z-07Z. SHIELD OF MID AND HIGH LVL
CLOUDS OVER EASTERN PA SHOULD PUSH EAST OF THE AREA BY ARND
06Z...AS SHORTWAVE AND ASSOC WAA ALOFT SHIFT EAST OF THE STATE.

CENTRAL PA WILL BE IN BTWN SHORTWAVES TONIGHT...ONE DEPARTING THE
E COAST AND NEXT SHORTWAVE DIVING ACROSS THE GRT LKS. LG SCALE SUBSIDENCE
BTWN THESE SYSTEMS SHOULD ENSURE A DRY FCST OVERNIGHT. MCLEAR SKIES
AND A CALM WIND WILL PROMOTE AREAS OF LATE NIGHT VALLEY FOG.
LATEST SREF AND RAP OUTPUT SUGGEST...UNLIKE MANY RECENT NIGHTS...SOME
OF THE FOG COULD AFFECT EVEN THE LOWER SUSQ VALLEY. DWPTS IN THE
50S SHOULD TRANSLATE TO ANOTHER MILD NIGHT FOR LATE SEPT...WITH
LOWS MOSTLY IN THE L/M 50S.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
A POTENT UPPER SHORTWAVE/LOW OVR THE GRT LKS WILL DIVE SE ACROSS
PA ON TUESDAY. DECREASING STABILITY UNDER THE COLD POOL ALOFT
WILL HELP SUPPORT THE DEVELOPMENT OF SCATTERED SHOWERS AND
THUNDERSTORMS. ENSEMBLES AND OPERATIONAL GUIDANCE INDICATE THAT
CAPE WILL BE MODEST...BUT FORECAST TOTAL-TOTALS IN EXCESS OF 50
ARE USUALLY A GOOD INDICATOR FOR THE POTENTIAL OF SOME LOW TOPPED
CONVECTION.

BASIN AVERAGE RAINFALL IS EXPECTED TO BE LIGHT...ON THE ORDER OF
0.10 OF AN INCH OR LESS...BUT AMOUNTS COULD BE SLIGHTLY HEAVIER...0.15
TO 0.25 OF AN INCH...ACROSS THE FAR NW TUESDAY AFTERNOON AND
EVENING.

MAX TEMPS TUESDAY ARE EXPECTED TO BE JUST A FEW DEG COOLER AND IN
THE LOWER TO MID 70S.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
PROGRESSIVE UPPER LOW/COMPACT TROF AXIS OVER THE NERN U.S. AT THE
START OF THE PERIOD IS FORECAST TO LIFT OUT BY THE END OF THE
WEEK...AS UPPER RIDGE REBUILDS ACROSS THE REGION INTO THE EARLY
PART OF THE WEEKEND. 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.

CLOUDIER AND MORE UNSETTLED WEATHER THAN RECENT DAYS IS EXPECTED
TO ACCOMPANY THE FIRST TROF WED...HOWEVER THE SYSTEM IS SOMEWHAT
MOISTURE-LIMITED AND SIGNIFICANT PCPN IS NOT EXPECTED. TEMPS ON
WED HOWEVER WILL BE COOLER THAN RECENT DAYS. WARMER WEATHER MAKES
A BRIEF RETURN THUR...FRI AND EARLY SAT AS THE UPPER RIDGE
REBUILDS....WITH MAXES AND MINS AT LEAST SEVERAL DEGREES ABOVE
CLIMO NORMALS.

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.
PASSAGE OF THE FRONT WILL ALSO BRING NOTICEABLY COOLER TEMPS TO
THE REGION FOR SUNDAY INTO MONDAY. A SHORT WAVE WITHIN THE THEN
EXPECTED CYCLONIC FLOW OVER THE REGION WILL BRING ANOTHER FRONTAL
SYSTEM TO THE REGION WITH AN INCREASED CHANCE OF SHOWERS FOR THE
END OF THE PERIOD.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
FOG ALREADY FORMING...ADJUSTMENTS MADE TO 03Z TAFS.

EARLIER DISCUSSION BELOW.

CLOUDS WILL CONTINUE TO THIN OVERNIGHT. DID HIT THE FOG
A LITTLE HARDER THAN IN THE 18Z TAF PACKAGE...ESPECIALLY WITH
HIGHER DEWPOINTS THIS EVENING THAN IN RECENT DAYS.

THERE WAS LITTLE FOG LAST NIGHT...AS MID AND HI CLDS
MOVED IN OVERNIGHT.

PERHAPS A FEW SHOWERS ACROSS THE WEST ON TUE.

WED...AN UPPER TROUGH/LOW DROPPING OUT OF THE GR LAKES INTO
THE LOCAL AREA WILL BRING SCT RAIN SHOWERS AND EVEN SOME
THUNDERSTORMS. LOW CIGS PROBABLE AT NIGHT.

OUTLOOK /THU THROUGH SAT/...

THU...LOW CIGS COULD LINGER MUCH OF THE DAY AS HIGH PRESSURE
TO THE EAST PROVIDES AN EAST-SOUTHEAST MARITIME FLOW.

FRI...SHOWERS AND THUNDERSTORMS PSBL ASSOC WITH GUSTY FROPA.

SAT...BREEZY WITH IMPROVING CONDITIONS. SHOWERS AND LOCAL MVFR
POSSIBLE OVER NWRN AREAS.

&&

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

&&

$$
SYNOPSIS...LA CORTE
NEAR TERM...DEVOIR/FITZGERALD
SHORT TERM...FITZGERALD/LA CORTE
LONG TERM...LAMBERT/GARTNER
AVIATION...MARTIN



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