FXUS61 KCTP 150243
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
943 PM EST MON DEC 14 2009

.SYNOPSIS...
A RIDGE OF HIGH PRESSURE OVER THE COMMONWEALTH WILL DRIFT
OFFSHORE TONIGHT ALLOWING A COLD FRONT TO PASS EARLY TUESDAY
FOLLOWED BY AN EXTENDED PERIOD OF BELOW NORMAL TEMPERATURES...AND
MOUNTAIN SNOW SHOWERS RIGHT INTO THE UPCOMING WEEKEND. AN AREA OF
LOW PRESSURE MAY DEVELOP ALONG THE SOUTHEAST COAST OF THE U.S.
SATURDAY NIGHT AND MOVE NORTHEAST...BRINGING A CHANCE FOR SOME
SNOW SUNDAY INTO MONDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
02Z SFC ANALYSIS PLACES SFC LOW JUST WEST OF LK ONTARIO WITH
TRAILING COLD FRONT ACROSS OHIO. BULK OF PRECIP PASSING WELL NORTH
OF PA ASSOCIATED WITH WAA AHEAD OF LOW. HOWEVER...A FEW -SHRA
SHOWING UP ON RADAR OVR WESTERN PA ALONG LL JET/PLUME OF HIGHER
PWATS. CAN/T RULE OUT A -SHRA OR TWO SURVIVING EAST OF THE MTNS
LATER TONIGHT. HOWEVER...WILL KEEP HIGHEST /CHC/ POPS ACROSS THE
OROGRAPHICALLY FAVORED ALLEGHENY MTNS.

INITIALLY ITS WARM ENUF ALOFT TO SUPPORT RAIN BUT DURING THE LATE
MORNING HOURS WE SEE DEEP ENUF COLD AIR MOVING IN TO CREATE A
CHANGE TO SNOW SHOWERS OVER THE NORTHWEST. I PUT A RAIN/SNOW MIX
ELSEWHERE. THE WESTERLY FLOW AND FAIRLY DRY UPSTREAM CONDITIONS
ARGUE FOR A SHARP DROP OFF IN POPS AS WE MOVE INTO CENTRAL AND
EASTERN AREAS...SO FOR TUES AFTERNOON I MENTIONED LITTLE MORE THAN
SCATTERED SPRINKLES OR FLURRIES OVER CENTRAL AREAS INTO THE
NORTHERN PARTS OF THE SUSQ VALLEY. TEMPS WILL NOT REALLY DROP OFF
UNTIL LATER IN THE DAY AND OVERNIGHT SO ANOTHER RELATIVELY MILD
DAY IS IN STORE.

&&

.SHORT TERM /TUESDAY NIGHT/...
TROUGH AXIS SWINGS THRU MID-ATLANTIC REGION AS FRONTAL BNDRY IS 
POISED TO PASS THRU PA EARLIER IN THE DAY...WITH A STEADY FEED OF 
COOLER AIR FILTERING INTO THE REGION. BNDRY LYR MOISTURE REMAINS 
SHALLOW UNTIL LATE AFTN/EVE...ONCE A WEAK VORT LOBE PIVOTS ARND 
TROUGH AXIS EARLY WED. THIS SHUD ELEVATE INVERSION HEIGHTS FOR THE 
NW MTNS...WITH MOISTURE ARRIVING IN THE DGZ OR ARND THE -20DEG C 
LYR. THUS STILL ANTICIPATE THAT LGT ACCUMS TUE NGT...THEN AGAIN FOR 
WED. ATTM IT APPEARS SUB-ADVISORY CRITERIA...HOWEVER A FEW 
LOCAL/HIGH TERRAIN AREAS COULD REACH CRITERIA. TEMPS WILL FALL INTO 
THE U-TEENS/L20S NW...M20S/U20S ELSEWHERE.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
GUIDANCE SUGGESTS A PERSISTENT PATTERN ARRIVING BEHIND FRONTAL 
PASSAGE TUE FOR WED THRU EARLY NEXT WEEK. CONFIDENCE BEGINNING TO 
INCREASE WITH RESPECT TO BLOCK OVER GREENLAND HOLDING THRU THE 
WEEKEND. EXPECT MID-LVL TROUGH TO ALSO MAINTAIN ITSELF ACROSS 
ONTARIO/QUEBEC...WHICH MAY ALLOW FOR WEAK VORT LOBES TO SLIDE SE 
FROM CENTRAL CANADA ACROSS THE GREAT LAKES REGION AND EVENTUALLY 
INTO THE MID-ATLANTIC. 

THE WILDCARD FOR THE SECOND HALF OF THE WEEKEND WILL BE THE 
INFLUENCE OF THE NORTH ATLANTIC BLOCK...AND POTENTIAL FOR A 
RETROGRADING 500MB VORT MAX INTO ONTARIO. A FEW GUIDANCE MEMBES HINT 
AT THIS SCENARIO...HOWEVER THE OVERALL CONFIDENCE IS THAT A 
CONTINUED NW FLOW PATTERN WILL MAINTAIN COOL CONDS. PRECIP APPEARS 
MINIMAL AS WELL. EXPECT DOWNSLOPING TO KEEP MINIMAL CLOUD COVER 
ACROSS THE SUSQ-VALLEY FOR THE AFTN HRS...WITH CONTINUED UPSLOPE AND 
LAKE EFFECT CLOUDS ACROSS THE ALLEGHENIES/NW MTNS. MAX TEMPS SHUD 
REMAIN UNIFORM FOR NEXT SEVERAL DAYS... ARND 30S TO U20S 
NW/CENTRAL...L30S/M30S FOR REMAINDER OF CWFA OVER THE WEEKEND/EARLY 
NEXT WEEK. OVERNIGHT LOWS WILL BE MAINLY IN THE TEENS/L20S...M20S 
ACROSS THE LOWER SUSQ-VALLEY FOR THE EXTENDED.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
LOW CLDS HUNG ACROSS EASTERN AREAS THIS AFT...WHILE OTHER AREAS
CLEARED OUT AS EXPECTED. MID DECK OVER THE AREA NOW...ALONG WITH
A FEW SPRINKLES NEAR THE NY BORDER. MOST AREAS VFR BUT FAR EASTERN
AREAS. THINK THIS WILL BE THE CASE FOR MUCH OF THE NIGHT.

LATER TONIGHT...SOME SHOWERS...AS FRONT NEEARS. MVFR AND IFR 
CONDITIONS TO PREVAIL LATER TONIGHT INTO TUE. RAIN SHOWERS WILL
MIX WITH SNOW SHOWERS ACROSS WESTERN AREAS LATER IN THE DAY.

SNOW SHOWERS ACROSS THE WESTERN AND NORTHERN MTS FOR LATE TUESDAY
NIGHT INTO WED.

HEIGHTS RISE SOME AS ONE HEADS INTO THU AND FRIDAY...WHICH WILL
ALLOW SNOW SHOWERS TO TAPER OFF. IT WILL BE BREEZY THROUGHOUT 
THE PERIOD.

OUTLOOK...

WED...MVFR IN -SHSN WEST AND NORTH. MAINLY VFR ELSEWHERE. 
GUSTY WNW WNDS. 
THU/FRI...BCMG VFR.
SAT...MAINLY VFR.

&&

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

&&

$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE/FITZGERALD
SHORT TERM...BEACHLER
LONG TERM...BEACHLER
AVIATION...MARTIN