-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 112221
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
521 PM EST WED DEC 11 2013

.SYNOPSIS...
A COLD CYCLONIC FLOW OVER THE GREAT LAKES WILL MAINTAIN BELOW
NORMAL TEMPERATURES THROUGH THE END OF THE WEEK...WITH LAKE
EFFECT SNOWS FOCUSED OVER FAR NORTHWEST PENNSYLVANIA IN THE
PERENNIAL SNOWBELT REGION. A PAIR OF WEAK CLIPPER SYSTEMS PASSING
TO THE NORTH WILL REINFORCE THE COLD AIR. FOR MOST OF THE AREA...THE
NEXT FEW DAYS WILL BE COLD AND DRY. THE ACTIVE EARLY SEASON WINTER
PATTERN LOOKS TO RESUME WITH ANOTHER STORM SYSTEM LIKELY IMPACTING
THE AREA SATURDAY INTO SATURDAY NIGHT...FOLLOWED BY MORE COLD AND
BRISK CONDITIONS INTO EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SAT IMAGERY SHOWS WEAK/MOISTURE LIMITED UPPER TROF MOVING EAST
ACROSS LAKE ERIE INTO WESTERN PA. PASSAGE OF THIS TROF SHOULD
SERVE TO RESTRUCTURE WIND FLOW TO ENHANCE LE SNOW SHOWER ACTIVITY
ACROSS NWRN COUNTIES INTO THURSDAY MORNING AS WELL AS INCREASE
COVERAGE OF CLOUDS AND ISOLATED SNOW SHOWERS ACROSS THE NRN AND
WRN MTNS. OTHERWISE LITTLE WIDESPREAD SIGNIFICANT WEATHER SHOULD
ACCOMPANY THIS TROF/SHORTWAVE GIVEN THE LIMITED MOISTURE.

LES ADVISORY REMAINS IN EFFECT FOR WARREN CO.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
A SERIES OF NRN STREAM IMPULSES ARE FCST TO RACE EWD ACRS THE GRT
LKS AROUND THE BASE OF LARGE POLAR VORTEX OVER HUDSON BAY. THE
VORTEX SHOULD GRADUALLY SHIFT TO THE NORTH AND EAST BY THE END OF
THE PERIOD AND ALLOW FOR AT LEAST MODEST 500MB HGT RISES AND
SLIGHTLY MODERATING TEMPS AS THE 1000-500DM THICKNESSES GRADUALLY
INCREASE. THERE IS SOME UNCERTAINTY FOCUSED ON THE UPSTREAM SIDE
OF THE TROUGH WITH PLACEMENT DIFFS OVER ONTARIO...WHICH APPEARS TO
IMPACT THE LOW-LEVEL TEMP GRADIENT AND MAGNITUDE OF HIGH PRES CELL
MOVING OVER MONTREAL CANADA BY 12Z SAT. THIS FEATURE LOOKS TO PLAY
A ROLE IN ANOTHER WINTER MIXED PCPN EVENT INTO THE WEEKEND.

IN GENERAL...EXPECT THE LAKE EFFECT SNOW MECHANISM TO FADE INTO
DAY 3 WITH THE FOCUS SHIFTING TO DEVELOPING LOW PRES/INVERTED
TROUGH OVER THE TN VLY AND ASSOCD WAA/OVERRUNNING PCPN POSSIBLY
REACHING THE AREA BY EARLY SATURDAY MORNING. DAY 2/THU LOOKS LIKE
THE COLDEST DAY BASED ON CONSENSUS GUIDANCE WITH HIGHS 20 DEGREES
BELOW NORMAL. WIND CHILLS WILL REMAIN A CONCERN AND WILL CONTINUE
TO HIGHLIGHT IN THE HWO. SUB-ZERO APPARENT TEMPS SEEM LKLY DURING
THE NIGHTTIME AND EARLY MORNING HOURS ACRS THE W-CNTRL MTNS.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
THE ACTIVE EARLY/COLD-SEASON PATTERN ACRS THE ERN CONUS WILL
RESUME THIS WEEKEND...LIKELY BRING MORE WINTER WEATHER TO THE AREA
FROM SATURDAY INTO EARLY SUNDAY. A CONSENSUS OF MODEL DATA AND
THEIR RESPECTIVE ENSEMBLE MEANS SHOW THE MOST LIKELY OUTCOME
BEING A TRANSFER OF SFC LOW PRESSURE FROM THE OHIO VALLEY TO THE
MID ATLANTIC COAST BY SATURDAY NIGHT...WITH SUBSEQUENT DEEPENING
OF THE COASTAL LOW AS AN ARCTIC VORTEX PLUNGES INTO THE GREAT
LAKES ON SUNDAY. THE FAR SE COULD GO OVER TO A COLD RAIN AROUND
33 DEGREES.

DID NOT CHANGE A LOT ON THE PACKAGE. SYSTEM IS SIMILAR TO WHAT
WE HAD LAST SUNDAY. EXPECT SOME LIGHT SNOW ON SATURDAY...MIXING
WITH SOME SLEET AND VERY LIGHT FREEZING RAIN/DRIZZLE ACROSS
SOUTHERN PA SATURDAY AFT INTO SATURDAY NIGHT.

BY 12Z SUNDAY...COLD ADVECTION WILL SET IN...AS THE COASTAL
TAKES OVER.

NOT SEEING A LOT OF SUPPORT FOR A REAL INTENSE SNOW BAND
NEAR THE MD BORDER AS WAS THE CASE ON SUNDAY. OVERALL EXPECT
MOST AREAS TO SEE 1 TO 3 INCHES...PERHAPS 4 TO 5 INCHES IN A FEW
SPOTS.

A COLD AND BLUSTERY WNW FLOW SHOULD FOLLOW BEHIND THE DEPARTING
COASTAL LOW WITH LAKE EFFECT/UPSLOPE SNOWS OVER THE NW MTNS AND
WRN HIGH TERRAIN LATER SUNDAY INTO SUNDAY NIGHT. HIGH PRES SHOULD
ARRIVE BY EARLY NEXT WEEK. TEMPS SHOULD MODERATE INTO TUE/WED AS
FLOW VEERS TO THE W/SW AHEAD OF A CLIPPER WAVE DROPPING ACROSS THE
NRN GREAT LAKES. LARGE SCALE HGT FALLS ASSOCD WITH ANOTHER POLAR
SHORTWAVE SPREADING ACRS THE GRT LKS/MID-ATLC MAY SPIN-UP ANOTHER
LOW OFF THE COAST...BUT AT THIS POINT ITS LATITUDE WOULD BE TOO
FAR NORTH TO IMPACT THE LOCAL AREA.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...

-- Changed Discussion --
VFR WILL CONTINUE OVER MOST OF THE REGION THROUGH THE EVENING
AND OVERNIGHT...EXCEPT FOR BFD WHERE IFR CONDITIONS WITH FREQUENT
SNOW SHOWERS WILL DOMINATE. JST COULD ALSO SEE BRIEF REDUCTIONS AS
UPSLOPE FLOW BRINGS CLOUDS AND SOME SNOW SHOWERS.

A WEAK COLD FRONT WILL MOVE ACROSS THE REGION TONIGHT REINFORCING
THE COLD FLOW OVER THE LAKES AND THE LAKE EFFECT SNOWS THAT WILL
CONTINUE OVER THE NW AND PARTS OF THE LAURELS.

ON THURSDAY...HIGH PRESSURE WILL BUILD OVER THE TN VALLEY AND SRN
APPALACHIANS BRINGING WIDESPREAD VFR CONDITIONS TO THE REGION ONCE
AGAIN. THOUGH BFD COULD LINGER WITH REDUCED CONDITIONS DUE TO
LAKE ENHANCED CLOUDS/SNOW SHOWERS INTO THURSDAY AFTERNOON.

OUTLOOK...

FRI...NO WIDESPREAD SIG WX.

SAT-SUN...SNOW OR MIXED PRECIP WITH LOW CIGS/VSBYS POSSIBLE.

MON...MAINLY VFR. PERHAPS A FEW SNOW SHOWERS NEAR THE NY
BORDER.
-- End Changed Discussion --

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ004.

&&

$$
SYNOPSIS...GARTNER/STEINBUGL
NEAR TERM...GARTNER
SHORT TERM...GARTNER/STEINBUGL
LONG TERM...MARTIN/STEINBUGL
AVIATION...LA CORTE/GARTNER/MARTIN