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Area Forecast Discussion
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000
FXUS61 KCTP 272234
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
534 PM EST THU NOV 27 2014

.SYNOPSIS...
A WEAK UPPER AIR DISTURBANCE WILL KEEP CLOUDS AND THE CHANCE OF A
FEW LIGHT SNOW SHOWERS IN THE FORECAST TONIGHT AND FRIDAY.
TEMPERATURES WILL BEGIN TO MODERATE THIS WEEKEND AS HIGH PRESSURE
MOVES OFF THE SE COAST. THE NEXT DISTURBANCE WILL BRING LIGHT
RAIN SHOWERS EARLY NEXT WEEK BEFORE A QUICK SHOT OF COOLER AIR FOR
MIDWEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
LATEST SFC ANALYSIS SHOWS A WEAK SFC LOW NEAR CAPE HATTERS AND
ALONG THE WEST COAST OF LAKE ONTARIO...SUPPORTED BY SEVERAL
SHORTWAVES SWINGING EAST FROM THE TENNESSEE VALLEY. THIS ENERGY
AND RESULTING SFC CONVERGENCE/UPSLOPE FLOW IS FORCING AN AREA OF
LIGHT SNOW ACROSS THE NRN AND CENTRAL MTNS THAT WILL AFFECT PARTS
OF CENTRAL PA INTO THE EVENING HOURS INTO THE CENTRAL COUNTIES.

AT THIS POINT STILL DO NOT EXPECT SIGNIFICANT SNOW ACCUMS WITH
BUT COULD BE ENOUGH TO COAT ROADS AND CAUSE SOME SLICK SPOTS...SO
HAVE UPDATED PHLHWOCTP TO GIVE THE PUBLIC/CUSTOMERS A HEADS UP.

BIGGEST QUESTION FOR THE OVERNIGHT WILL BE WHETHER A PERIOD OF
MORE ORGANIZED LAKE EFFECT CAN GATHER ITSELF OVER NWRN AREAS. DEEP
LAYER FLOW DOES LOOK FAVORABLE FOR A TIME TONIGHT...BUT RELATIVELY
SHORT OVER-LAKE TRAJECTORIES SHOULD LIMIT SNOWFALL TO MAINLY SUB
ADVISORY LEVELS.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
INVERSION HEIGHTS ARE EXPECTED TO LOWER FRIDAY WHICH SHOULD PUT A
DAMPER ON ANY OF THE BEST DEVELOPED LAKE EFFECT BANDS...BUT CLOUDS
AND PERHAPS A FEW SNOW SHOWERS WILL REMAIN POSSIBLE OVER THE
NORMAL WESTERN AND NORTHERN LOCATIONS. THE BEST CHANCES WILL BE
IN THE MORNING...WITH BRIGHTENING SKIES LIKELY IN THE AFTERNOON.

HIGHS WILL BE A FEW DEG COOLER THAN TODAY AS THE CORE OF THE POST
FRONTAL COLD AIR SETTLES OVERHEAD.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
BROAD ZONAL FLOW DEVELOPS DURING THE WEEKEND. THIS WILL PROMPT A
WARM-UP AS LOW LEVEL FLOW VEERS TO THE SW AS HIGH PRESSURE SLIPS
OFF FURTHER TO OUR SOUTHEAST.

AFTER A CHILLY NIGHT FRI NIGHT WITH LOWS INVOF 20F...THE AIRMASS
WILL BEGIN MODERATING ON SATURDAY...WITH READINGS REACHING THE
MID 40S TO MID 50S BY SUNDAY. MAY SEE SCT LIGHT SHSN ACROSS NW
MTNS IN WEAK NW/W FLOW.

MODELS SEEM TO BE BACK IN BETTER AGREEMENT ON APPROACH OF A FRONT
FOR MONDAY...THOUGH GFS/GEFS CONTINUE TO BE 6 TO MAYBE 12 HRS FASTER
WITH FROPA. 

AHEAD OF THAT...ONE AREA OF POSSIBLE CONCERN COULD BE THE
EXPECTED DEVELOPMENT OF SOME LIGHT WARM ADVECTION PRECIP SATURDAY
NIGHT INTO SUNDAY MORNING MAINLY ACROSS WESTERN SECTIONS. TEMPS
ALOFT WARM RAPIDLY...AND I KEPT FORECAST SURFACE MINS MAINLY ABOVE
FREEZING. BUT IF WE END UP A FEW DEG COOLER...WE COULD SEE A
PERIOD OF SOME LIGHT ICING UNTIL TEMPERATURES CAN RECOVER SUNDAY.

POST FRONT WILL BRING COOLER TEMPS BACK IN FOR MIDWEEK AS LARGE
SURFACE HIGH SLIDES ACROSS S CANADA...BUT NOTABLE MODEL DIFFS
BEGIN TO DEVELOP AROUND THEN WITH ECMWF MUCH FLATTER THAN GFS. EC
SOLUTION BRINGS HIGH PRESSURE OVER THE REGION BY LATE WEEK WITH
SLOWLY MODERATING TEMPS...WHILE THE GFS/GEFS SPINS UP A SURFACE
LOW OVER THE MIDWEST WHICH WOULD PUSH EVEN WARMER TEMPS OUR WAY.
FOR NOW...TEMPERED WARMUP A BIT AS MUCH UNCERTAINTY IN LATER TIME
PERIODS.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
AN UPPER LEVEL TROUGH WILL CROSS THE REGION TONIGHT AND EARLY
FRIDAY...DRIVING A NEW SURGE OF COLD AIR OVER THE RELATIVELY WARM
LAKES. A SUFFICIENT NORTHWESTERLY FETCH WILL BE IN PLACE FOR
NUMEROUS SNOW SHOWERS AND A FEW BRIEF/HEAVY SQUALLS OVER THE WRN
1/3 OF THE AIRSPACE - PRIMARILY AT THE HIGHER ELEVATION TERMINALS
IN ZOB SECTOR. PERIODS OF IFR ARE A GOOD BET AT JST/BFD WITH OCNL
VISBY REDUCTIONS BLW 1SM. DOWNSLOPE  TO THE EAST SHOULD KEEP MVFR
TO VFR CONDS IN PLACE THRU FRIDAY. THE SHSN ACTIVITY SHOULD TAPER
DOWN OVER THE WRN SXNS BY LATER FRIDAY AFTERNOON WITH IMPROVING
CONDS EXPECTED AT BFD AND JST.

OUTLOOK...
FRI...IFR-MVFR/-SHSN WEST...IMPROVING. MVFR TO VFR ELSEWHERE. 

SAT...VFR/MVFR. ISOLD -SHRASN PSBL.

SUN...MVFR/IFR. OCNL -SHRA NW 1/2. 

MON...MVFR WITH OCNL IFR. SCT -SHRA. COLD FROPA/WND SHFT 250-300.

TUE...VFR/MVFR CIGS. NO SIG WX.

&&

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

&&

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



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