Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 260310
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1010 PM 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 AND SUNDAY. A SERIES
OF WEAK STORM SYSTEMS PASSING SOUTH OF PA EARLY NEXT WEEK MAY
BRING SOME LIGHT SNOW TO THE KEYSTONE STATE AT TIMES. COLDER
AIR WILL SLOWLY WORK SOUTHWARD INTO PENNSYLVANIA...AS A LARGE
HIGH PRESSURE SYSTEM BUILDS INTO THE PLAINS.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
STRATOCU REMAINS TRAPPED BENEATH INVERSION ACROSS THE NW HALF OF
PA LATE THIS EVENING...WHILE DRYING/DOWNSLOPING FLOW HAS PRODUCED
CLEARING ACROSS THE SE COUNTIES. HIGH PRESSURE BUILDING INTO THE
AREA OVERNIGHT WILL CAUSE WINDS TO DIMINISH AND FALLING INVERSION
HGT WILL RESULT IN CLEARING SKIES EAST OF THE ALLEGHENY FRONT. MDL
SOUNDINGS INDICATE THE SHALLOW CLOUD LYR WILL PERSIST ALL NIGHT
ACROSS THE NW MTNS.

LOW TEMPS TONIGHT WILL BE FAIRLY UNIFORM IN THE U20S TO
L30S...QUITE A BIT ABV NORMAL FOR LATE DECEMBER.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
FRIDAY SHOULD PROVIDE ABOUT THE MOST WIDESPREAD SUNSHINE WE HAVE
SEEN IN MANY A DAY...AS RIDGING AT THE SFC AND ALOFT BUILDS OVR
THE AREA. THERE MAY BE SOME LINGERING AM STRATOCU ACROSS THE NW
MTNS...BUT EVEN THERE SKIES SHOULD BRIGHTEN TO AT LEAST PARTLY
SUNNY.

18Z GEFS MEAN 925 TEMPS ARND 2C SHOULD SUPPORT HIGHS FROM ARND
40F OVER THE HIGHEST TERRAIN OF THE NW...TO NEAR 50F ACROSS THE SE
PIEDMONT.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
AFTER BEING AT 41 DEGREES ALL SHIFT...NOW 39 WITH JUST A FEW SNOW
FLAKES OUTSIDE THE OFFICE FOR CHRISTMAS.

ANYWAY...AFTER A NICE MILD DAY ON FRIDAY...ANOTHER MILD AND
MAINLY SUNNY DAY WILL BE ON TAP FOR SAT. A WELCOME BREAK FROM THE
RECENT CLOUDY PERIOD...LAST TIME I SAW MUCH SUN WAS NORTH OF THE
PA BORDER ON 12/2. ANYWAY...ENJOY THE MILD SPELL.

FOR SUNDAY INTO MID WEEK...MODELS HAVE BEEN SHOWING SOME SPREAD
WITH POTENTIAL FOR COASTAL STORMS.

MEAN RIDGE IS WELL TO THE WEST. THIS SHOULD HELP KEEP A W-SW FLOW
ALOFT WITH HIGHER THAN NORMAL HEIGHTS ACROSS THE EAST. THIS WILL
TAPER THE COLDER AIR...AS A LARGE HIGH BUILDS INTO THE STATES.
ALSO THIS WILL CUT BACK THE RISK OF A MAJOR COASTAL STORM.

INSTEAD...A SERIES OF FAST MOVING WEAK SYSTEMS WILL LIKELY PASS
JUST SOUTH OF PA.

TEMPS SUNDAY WILL START OFF MILD...THUS MAINLY RAIN. BY LATE
SUNDAY NIGHT...IT SHOULD BE COLD ENOUGH FOR JUST MAINLY SNOW.

THE CHC FOR SNOW TAPERS DOWN BY LATE WED...IF NOT SOONER.

MINOR ADJUSTMENTS MADE TO THE GRIDS.

MERRY CHRISTMAS TO ALL.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
03Z UPDATE...
WESTERN EDGE OF THE LOW CLOUD DECK IS MOVING STEADILY EASTWARD.
EASTERN EDGE INCHING TO THE NORTHWEST. SO NO LARGE CHANGES...ONLY
TO TWEAK FOR THE RECESSION OF CLOUDS AT AOO AND ALLOW FOR LIGHTER
WINDS AT A FEW LOCATIONS.

PREV...
THE WIND AT MOST SITES HAS SLACKENED AND WILL
CONTINUE TO DO SO AS THE SFC RIDGE AXIS SLIDES OVERHEAD TONIGHT.
THE PRESSURE GRADIENT WILL STILL LEAD TO SOME LIGHT WIND...BUT
SPEEDS SHOULD BE LESS THAN 10 KTS ON THE WHOLE...WITH IPT PERHAPS
GOING CALM FOR A TIME. THE CLOUDS ARE THE MOST INTERESTING PART OF
THIS AVIATION FORECAST THIS EVENING. THE TYPICAL WESTERLY FLOW AND
DOWNSLOPING CLOUD PATTERN OF CLEARING SE OF THE RIDGE AND VALLEY
REGION IS ON DISPLAY FOR ALL TO SEE. THE SFC RIDGE AND ASSOCIATED
SUBSIDENCE IS BUILDING IN AND PRESSING DOWN ON THE THIN LAYER OF
MOISTURE THAT IS THE CLOUD DECK. IN GENERAL...WE WOULD EXPECT A
GRADUAL E-W CLEARING TO OCCUR TONIGHT AS THE INVERSION LOWERS. THE
SAME LOW CLOUD DECK IS BACK TO THE OH/IN BORDER...AND IS STARTING
TO CLEAR FROM SWRN OH AT 00Z. WITH THE RECENT CLOUDY STRING WE
HAVE HAD IT IS DIFFICULT TO FATHOM THAT THE AREA WILL ENTIRELY
CLEAR OUT TONIGHT...AND LLVL RH PLOTS SUPPORT THIS GLOOMY
SUPERSTITION. BUT...PREV FORECASTS AND CURR MODEL GUID DOES
INDICATE THAT THE MVFR CLOUDS DO GET EATEN AWAY EARLY TONIGHT AT
ALL BUT JST AND BFD. WILL JUST MAKE IT A BIT MORE PESSIMISTIC THAN
THAT AND CLEAR IT MORE SLOWLY. FRIDAY SEEMS LIKE A /FINALLY/ SUNNY
DAY. THE NEXT CHC OF PRECIP WILL BE SAT NIGHT AS ANOTHER MID-
CONTINENT TROUGH AGAIN PULLS SOME GULF MOISTURE UP TO THE WEST OF
THE AREA. BUT THE RESULTANT PRECIP AND SEVERITY OF THE AIRMASS
CHANGE LOOK LESS IMPRESSIVE THAN WHAT WE JUST WENT THROUGH.
HOWEVER...IT WILL END UP COOLING OFF THE TEMPS MORE CERTAINLY THAN
THE LATEST ATTEMPT AT RETURNING TO WINTER.

OUTLOOK...

SAT...VFR.

SAT NITE-SUN...MVFR/IFR WITH SCATTERED RAIN OR SNOW SHOWERS.

MON-TUE...MAINLY VFR. PERHAPS MVFR IN SOME LIGHT SNOW
AT TIMES...MAINLY NW PA AND FAR SOUTHERN PA.

&&

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

&&

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



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