Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 200000
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
700 PM EST FRI DEC 19 2014

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE WESTERN GREAT LAKES WILL SLIDE
EAST ACROSS PENNSYLVANIA THIS WEEKEND...BRINGING DRY WEATHER WITH
LIGHTER WIND. A DEEP UPPER TROUGH AND ASSOCIATED SFC LOW WILL LIFT
NORTHEAST THROUGH THE GREAT LAKES DURING THE MIDDLE OF NEXT WEEK
LIKELY BRINGING US RAIN AND WIND FOR CHRISTMAS EVE...THEN BLUSTERY
AND COLDER CONDITIONS FOR CHRISTMAS DAY WITH SCATTERED SNOW
SHOWERS.

&&

.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
7 PM UPDATE...
BIG BREAKS IN CLOUDS LOCALLY. NRLY FLOW IS SHOVING THE CLOUDS DOWN
INTO THE POCONOS AND TRYING TO GET THEM INTO LEB/LANC COS. AT THIS
POINT...WILL CONTINUE TO COUNT ON THE DOWNSLOPE TO KEEP IT FROM
GOING TOTALLY OVC...BUT SOME INCREASE IN CLOUDS OVER THE NEXT FEW
HRS IN THE SE IS PROBABLY A GOOD CALL. OTHERWISE...THE SUBSIDENCE
IN BETWEEN THE NERN AND SERN PARTS OF THE STATE MAY CONTINUE TO
OPEN UP BIGGER BREAKS. WILL HAVE TO TWEAK NWRN MIN TEMPS AS THEY
ARE EXTREMELY CLOSE TO GOING MINS ATTM. ELSEWHERE...DEWPOINTS AND
ONLY SLOW DECREASE IN COVG LOOK LIKE THE MINS ARE OKAY FOR NOW.

PREV...
STUBBORN...ALBEIT SHALLOW STRATO CU CLOUD DECK TRAPPED BELOW A
MODERATELY STRONG SUBSIDENCE INVERSION /BASED AT AROUND 2-3KFT
AGL/ WILL PERSIST ACROSS MUCH OF NORTHERN AND WESTERN PENNSYLVANIA
LATE TODAY INTO SATURDAY...WHILE PARTIAL CLEARING OCCURS ACROSS
THE LOWER SUSQ VALLEY AND SURROUNDING AREAS.

TEMPS WILL REMAIN STEADY THROUGH LATE THIS AFTERNOON UNDER THE
10-15 KT NWRLY FLOW. READINGS WILL VARY FROM THE MID TO UPPER 20S
ACROSS THE NORTHERN AND WESTERN MOUNTAINS...TO THE LOWER 40S IN
THE SOUTHEAST.

A WEAK SFC RIDGE WILL MOVE TO NEAR THE PENN/OHIO BORDER BY 12Z
SATURDAY...BUT THE WEAK WESTERLY ISENTROPIC LIFT ALONG THE 285K
THETA SFC...AND SOME SHALLOW MOISTURE BEING ADVECTED SWD INTO THE
NRN MTNS OF PENN FROM LAKE ONTARIO...WILL MAINTAIN MOSTLY CLOUDY
TO CLOUDY SKIES. LITTLE MORE THAN A FEW FLURRIES OR SPOTTY -FZDZ
WILL FALL FROM THIS THIN CLOUD LAYER ACROSS THE HIGHER TERRAIN OF
THE LAURELS AND INVOF KBFD.

AFTER A PTLY CLOUDY LATE AFTERNOON AND EVENING IN THE SE PART OF
THE CWA...A BKN LAYER OF STRATO CU IS EXPECTED TO DRIFT SE /OR
FORM/ ACROSS THE REGION OVERNIGHT.

DUE TO THE NW-SE GRADIENT OF DECREASING CLOUDS...LOW TEMPS AT
DAYBREAK SAT WILL BE IN A RATHER TIGHT RANGE...FROM THE UPPER
TEENS TO LOWER 20S ACROSS THE MOUNTAINS...TO THE LOWER 20S IN THE
SE

&&

.SHORT TERM /7 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
A RIDGE OF HIGH PRESSURE...LIGHTER WIND...AND ASSOC DRIER AIR
MASS WILL BUILD EAST ACROSS THE STATE SATURDAY...PROVIDING THE
AREA WITH FAIR WEATHER.

HIGH RES MODEL DATA CONTINUES TO PAINT A MOSTLY CLOUDY PICTURE FOR
MUCH OF THE REGION SATURDAY INTO SATURDAY NIGHT...THOUGH PERIODS
OF SUNSHINE ARE LIKELY THROUGHOUT THE CENTRAL RIDGE AND VALLEY
REGION...AND SUSQUEHANNA RIVER VALLEY.

WAA ALOFT IN ADVANCE OF SHORTWAVE LIFTING OUT OF THE MISS VALLEY
WILL LIKELY SPREAD SOME THIN CIRRUS OVER THE LOWER/THIN STRATO CU
CLOUD DECK PRESENT ACROSS THE REGION SATURDAY. ALL 12Z OPERATIONAL
MODEL DATA CONTINUES TO SUPPORT A DRY DAY WITH SFC RIDGE AND LOW
PWAT AIRMASS OVR THE STATE. MAX TEMPS SHOULD BE FAIRLY CLOSE TO
SEASONAL NORMS NEAR 30 ACROSS THE MTNS...AND MID TO UPPER 30S IN
THE SE.

MOSTLY CLOUDY SKIES WITH LIGHT WIND SAT NIGHT WILL YIELD LOWS IN
THE LOWER 20S ACROSS THE MTNS...AND GENERALLY THE MID 20S
ELSEWHERE.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
HIGH PRES WILL PROVIDE TRANQUIL WEATHER ON SUNDAY...WITH PARTLY TO
MOSTLY SUNNY SKIES AND SEASONABLE TEMPS. AFTER THAT...THE WEATHER
WILL BECOME INCREASINGLY UNSETTLED AS NEXT WEEK PROGRESSES.

CLOUDS WILL INCR SUNDAY NIGHT INTO MONDAY...AS HIGH PRES LOSES
ITS GRIP AND A WEAK AREA OF LOW PRES ORGANIZES OVER THE SERN UNITED
STATES. LIGHT PRECIP WILL WORK NWD INTO PENNSYLVANIA LATE MONDAY
INTO MONDAY NIGHT AND CONTINUE INTO TUES. INITIALLY...CONDS WILL
BE COLD ENOUGH FOR THE POSSIBILITY OF SOME WINTRY PRECIP.
HOWEVER...WARMER AIR WILL MAKE ITS WAY NWD LATER MONDAY NIGHT INTO
TUES AND GRADUALLY CHANGE ANY LINGERING PRECIP OVER TO PLAIN RAIN.

A MORE SIGNIFICANT STORM SYSTEM WILL GET ORGANIZED OVER THE
MISSISSIPPI VALLEY TUES NIGHT BEFORE PUSHING NWD INTO THE GREAT
LAKES ON WED. THIS SYSTEM WILL DRAW EVEN MILDER AIR NWD INTO THE
REGION...AND PROVIDE A RAINY AND BREEZY CHRISTMAS EVE DAY.

AS THIS SYSTEM DRIFTS NWD INTO SRN CANADA...COLDER AIR WILL WRAP
INTO THE REGION ON BLUSTERY WEST WINDS. A CHANGEOVER FROM RAIN TO
SNOW SHOWERS FROM WEST TO EAST ACROSS PA IS POSSIBLE LATE WED/WED
NIGHT. SCT SNOW SHOWERS WILL CONTINUE INTO THURS ACROSS MAINLY
NRN AND WRN PA.

THE CHILLIER AIRMASS LOOKS LIKE IT WILL BE SHORT-LIVED...WITH
OPERATIONAL MODELS AND THE GEFS SHOWING 850HPA TEMPS ALREADY
BEGINNING TO RISE NEXT FRI.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
LLVL NWRLY FLOW AND OROGRAPHIC FORCING OF A SHALLOW MOIST LAYER
WILL CONTINUE TO PRODUCE PLENTY OF CLOUDS ACROSS THE NW 1/2 TO
2/3RDS OF THE STATE WITH MAINLY MVFR BKN-OVC CIGS THROUGH
TONIGHT. KJST AND KBFD MAY TEETER ON THE UPPER END OF IFR FOR A
FEW HOURS LATER TONIGHT /AFTER 06Z/. IN CONTRAST...THE SE PENN
AIRFIELDS SUCH AS KMDT...KTHV AND KLNS WILL SEE MAINLY VFR...WITH
SKY CONDITIONS VARYING SCT-BKN030-040.

NORTHWEST WINDS OF 10-15 KTS WITH HIGHER GUSTS WILL DECREASE TO 8
KTS OR LESS LATER TONIGHT AND SATURDAY.

HIGH PRESSURE BUILDS EAST ACROSS PENN SATURDAY...WITH BKN-OVC CIGS
VARYING BETWEEN MVFR OVER THE HIGHER TERRAIN OF THE NORTH AND
WEST...TO SCT-BKN VFR IN THE VALLEYS.

OUTLOOK...

SUN...NO SIG WX EXPECTED.

MON...LOW CIGS WITH LGT RAIN/SNOW POSSIBLE. BECOMING BREEZY.

TUE...LOW CIGS WITH RAIN LIKELY. BREEZY.

WED...MILD WITH PERIODS OF RAIN OF VARYING INTENSITY...LEADING TO
MVFR TO IFR. ALSO...WINDY WITH LLWS.

&&

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

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...DANGELO/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...EVANEGO
AVIATION...LAMBERT/CERU


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