Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 200636
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
136 AM EST SAT DEC 20 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 8 AM THIS MORNING/...
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 CENTRAL PENNSYLVANIA EARLY THIS
MORNING. APPROACH OF SFC HIGH AND FALLING INVERSION HGT HAS
RESULTED IN PARTIAL CLEARING ACROSS THE SC MTNS AND NR TERM MDL
SOUNDINGS INDICATE THIS AREA WILL REMAIN MCLEAR THRU DAWN...WHILE
STRATOCU PERSISTS ELSEWHERE. TEMPS ON TRACK TO BOTTOM OUT IN THE
20S.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM SUNDAY/...
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 NIGHT 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 /06Z SATURDAY THROUGH WEDNESDAY/...
NORTHWESTERLY SFC FLOW THAT HAS CAUSED OROGRAPHIC FORCING OF A
SHALLOW MOIST LAYER WILL CONTINUE TO PRODUCE PLENTY OF CLOUDS
ACROSS THE NW AND THE LAURELS WITH MAINLY MVFR BKN-OVC CIGS
THROUGH TONIGHT. KJST AND KBFD WILL TREND IFR THROUGH 12Z...AND
CIGS WILL SLOWLY INCREASE AS THE LOW LEVELS DRY OUT BY MID TO LATE
TOMORROW MORNING. IN CONTRAST...THE SE PENN AIRFIELDS SUCH AS
KMDT...KTHV AND KLNS WILL SEE MAINLY VFR.

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...FITZGERALD
SHORT TERM...LAMBERT
LONG TERM...EVANEGO
AVIATION...LAMBERT/CERU



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