Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 251552
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1052 AM EST THU DEC 25 2014

.SYNOPSIS...

A LARGE AREA OF HIGH PRESSURE WILL BUILD NORTHEAST FROM THE GULF
COAST REGION BRINGING FAIR WEATHER WITH DIMINISHING WINDS THAT
WILL LAST THROUGH THE END OF THE WEEK. A WEAK COLD FRONT WILL
DRIFT SLOWLY ACROSS THE STATE SATURDAY NIGHT INTO SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

THE COLD FRONT IS CLEARING THE NEW ENGLAND COASTAL WATERS AS OF
MID MORNING...LEAVING BEHIND A STRONG PRESSURE GRADIENT AND GUSTY
WINDS OVER CENTRAL PA. THE PRESSURE GRADIENT WILL STEADILY WEAKEN
TODAY SO THE NOON TIME END TIME OF THE WIND ADVISORY LOOKS
REASONABLE.

COLDER AIR ALOFT AND SLIGHTLY CYCLONIC LOW LEVEL FLOW WILL SUPPORT
SOME SNOW SHOWERS ACROSS THE USUAL HIGHER ELEVATIONS OF THE WEST
AND NORTH THROUGH EARLY AFTERNOON. CONDITIONS WILL STEADILY
IMPROVE THIS AFTERNOON AS INVERSION HEIGHTS BEGIN TO
LOWER...CUTTING OFF THE SNOW SHOWERS AND HELPING TO TRIM THE
WINDS.

WITH SFC TEMPS EXPECTED TO BE ABV FREEZING EVERYWHERE ANY LIGHT
SNOW SHOWERS ARE NOT EXPECTED TO ACCUMULATE...EXCEPT FOR PERHAPS A
DUSTING OVR THE HIGHEST RIDGETOPS.

ENS MEAN 925/850 TEMPS SUPPORT HIGH TEMPS TODAY RANGING FROM THE
M30S OVR THE ALLEGHENY MTNS...TO THE U40S ACROSS THE LOWER SUSQ
VALLEY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
SFC HIGH PRESSURE WILL BUILD NE INTO THE REGION LATE TONIGHT AND
FRIDAY...ACCOMPANIED BY DECREASING WSW WIND AND CLEARING SKIES
ACROSS ALL BUT PORTIONS OF THE WESTERN MTNS WHERE SOME SHALLOW
STRATUS/STRATOCU WILL BE PRESENT...ALONG WITH THE CHC FOR SOME
VERY LIGHT SNOW OR -FZDZ AS CLOUD TEMPS WILL BE JUST A FEW TO
SEVERAL DEG C BELOW ZERO.

LOW TEMPS TONIGHT WILL BE FAIRLY UNIFORM AND IN THE MID TO UPPER
20S.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
POTENT LONGWAVE UPPER TROF EXITING THE EAST COAST AT THE START OF
THE PERIOD WILL BE REPLACED BY UPPER RIDGING INTO THE WEEKEND. AS
LONGWAVE UPPER TROFFING IS FORECAST TO DEVELOP OVER THE WRN US
STARTING EARLY IN THE PD AND NRN STREAM ENERGY RETREATS INTO
EASTERN CANADA...MDT TO STRONG SWRLY FLOW ALOFT IS THEN FORECAST
TO DOMINATE THE EASTERN CONUS FROM LATE IN THE WEEKEND THROUGH THE
REMAINDER OF THE YEAR.

MEDIUM RANGE GUIDANCE IS FAIRLY CONSISTENT ESPECIALLY EARLY IN
THE PERIOD...BUT THEN SOME DIFFERENCES ARISE IN 500MB FLOW
PATTERN AFTER MONDAY AS THE ECMWF MOVES ENERGY EAST FASTER...WHILE
THE GFS CLOSES OFF AN UPPER LOW OVER THE DESERT SW.

A NORTHERN STREAM WAVE IS FORECAST TO SUPPORT A COLD FRONT MOVING
EAST ACROSS THE STATE LATE IN THE WEEKEND...POSSIBLY STALLING
NEAR THE MASON DIXON LINE INTO MONDAY AS IT ENCOUNTERS RESISTANCE
FROM THE BUILDING UPPER FLOW. THIS FRONT LOOKS TO BE THE MAIN
FOCUS FOR PCPN IN THE LONG TERM PERIOD. WITH SNOW TO THE NORTH AND
WEST...AND A MIX TO RAIN ACROSS THE SOUTH.

WITH RIDGING OR SWRLY FLOW ALOFT MUCH OF THE PERIOD WILL FEATURE
ABOVE NORMAL TEMPS...WITH A COOL DOWN TOWARD NORMAL BY NEW YEARS
EVE.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...

WESTERN HIGH TERRAIN TERMINALS WILL REMAIN MVFR WITH PASSING SNOW
SHOWERS DROPPING VISIBILITIES TO IFR AT TIMES INTO THE LATE
AFTERNOON OR EARLY EVENING...BEFORE CONDITIONS IMPROVE TO VFR.
CENTRAL AND EASTERN TERMINALS WILL BE MAINLY VFR WITH CEILINGS
BETWEEN ABOUT 3000-6000` WITH LITTLE MORE THAN A BRIEF SPRINKLE OR
FLURRY.

GUSTY WESTERLY WINDS WILL SLOWLY DIMINISH TODAY WITH THE APPROACH
OF HIGH PRESSURE LEADING TO FAIR SKIES OVERNIGHT WITH WINDS
GENERALLY 10-15 MPH OR LESS.

OUTLOOK...

FRI-SAT...VFR.

SUN-MON...MVFR TO IFR WITH SCATTERED RAIN AND SNOW SHOWERS.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL NOON EST TODAY FOR PAZ004>006-010>012-017-
018-024-033.

&&

$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/GARTNER
AVIATION...LA CORTE/ROSS



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