Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 172007 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 307 PM EST WED DEC 17 2014 .SYNOPSIS...
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BRISK WESTERLY WINDS WILL BRING IN COLDER AIR THIS AFTERNOON THROUGH FRIDAY NIGHT. SCATTERED...MAINLY MOUNTAIN SNOW SHOWERS ARE EXPECTED THROUGH THE END OF THE WEEK AS CLOUDY AND COLD CONDITIONS PERSIST. A WEAK LOW PRESSURE AREA IS EXPECTED TO MOVE WELL SOUTH OF THE REGION THIS WEEKEND...BUT MOST OR ALL OF THE PRECIPITATION WILL STAY TO THE SOUTH OF THE STATE.
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&& .NEAR TERM /THROUGH TONIGHT/...
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GUSTY WESTERLY WINDS WILL ADVECT SEASONABLY COLD AIR INTO THE REGION LATE THIS AFTERNOON AND TONIGHT. NARROW...EAST-WEST BANDS OF SNOW SHOWERS WILL OCCUR ACROSS MAINLY THE HIGHER TERRAIN OF THE NORTH AND WEST THIS AFTERNOON...WHILE ANY SNOW SHOWERS THROUGHOUT THE CENTRAL RIDGE AND VALLEY REGION FROM THE RELATIVELY SHALLOW STRATOCU DECK WILL BE ISOLATED AND BRIEF /THANKS TO DECREASING LAPSE RATES IN THE 850-700MB LAYER/. OCCASIONAL BREAKS IN THE CLOUD DECK WILL OCCUR ACROSS THE SCENT AND SERN COUNTIES. NO SNOW ACCUMULATION WILL OCCUR THROUGHOUT THE CENTRAL VALLEYS AND NEAR THE ALLEGHENY FRONT WHERE TEMPS WILL BE IN THE MID TO UPPER 30S. HOWEVER...A COATING TO ONE HALF OF AN INCH IS POSSIBLE ACROSS THE HIGHER TERRAIN CLOSE TO THE PA/NY BORDER WHERE MORE PERSISTENT/STEEPER LOW-MID LEVEL LAPSE RATES WILL BE FOUND. TEMPS WILL BE NEARLY STEADY OR SLOWLY FALLING FOR THE REST OF THE DAYLIGHT HOURS...RANGING FROM 30-32 ACROSS THE NW MTNS AND LAURELS...TO THE MID 40S IN THE LOWER SUSQ VALLEY. A COMPACT...THOUGH MDTLY STG MID-LEVEL SHORTWAVE WILL TRACK ESE ACROSS THE FCST AREA BETWEEN ABOUT 00-07Z THURSDAY /AT THE NRN EDGE OR LEFT EXIT REGION OF A POTENT 130 KT UPPER JET/ WITH A DISTINCT POCKET OF RELATIVELY STEEP...850-700MB LAPSE RATES IN EXCESS OF 5C/KM. THIS FEATURE SHOULD SUPPORT A FEW HOUR PERIOD OF SCT-NUMEROUS SNOW SHOWERS /THIS EVENING UNTIL SHORTLY AFTER MIDNIGHT/ WITH THE POTENTIAL FOR A QUICK GROUND WHITENING - EVEN ACROSS THE CENTRAL MTNS AND SUSQ VALLEY. MINS TONIGHT WILL FALL INTO THE 20S AND EVEN SOME UPPER TEENS IN THE HIGHEST ELEVS OF THE LAURELS. WIND CHILLS WILL BRUSH THE SINGLE DIGITS THERE. WEST TO NW WINDS WILL AVERAGE 10-15 KTS WITH GUSTS IN THE 20S LATE TODAY THROUGH TONIGHT. LOW TEMPS AT DAYBREAK THURS WILL BE NEAR 20F ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST...AND IN THE MID TO UPPER 20S THROUGHOUT THE SUSQ VALLEY.
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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THE PATTERN WILL REMAIN SEASONABLY COLD AND BRISK THROUGH THE END OF THE WEEK. LARGE SCALE SUBSIDENCE ASSOCIATED WITH SURFACE HIGH MIGRATING EAST FROM THE GREAT LAKES/MIDWEST INTO EASTERN CANADA SHOULD BRING AN END TO NUISANCE/MINOR SNOW SHOWER ACTIVITY AND LINGERING FLURRIES OVER THE NW ALLEGHENIES BY FRI NGT. CONCERNING THE WEEKEND SYSTEM... THE MODELS SHOW A SOUTHERN STREAM TROUGH DEVELOPING TOWARD THE SOUTHERN ROCKIES AND PLAINS ON FRIDAY WITH THE ASSOCIATED HEIGHT FALLS INVIGORATING A WAVE OF LOW PRESSURE OVER THE WESTERN GULF COAST STATES BY 00Z SAT. THERE REMAINS A BROAD MODEL CONSENSUS IN TRACKING THE DEVELOPING SFC WAVE EAST-NORTHEAST ACROSS THE SOUTHEAST PIEDMONT BEFORE EXITING THE LOWER 48 INVOF THE CAROLINA COASTAL PLAIN---BETWEEN HATTERAS AND MYRTLE BEACH. WHILE THERE IS MUCH BETTER MODEL AGREEMENT AND CONVERGENCE TOWARD A WEAKER/MORE SUPPRESSED SOLUTION OVER THE LAST 2 MODEL CYCLES...THERE IS STILL ENOUGH SPREAD/UNCERTAINTY IN THE EVOLVING SPLIT-FLOW PATTERN THAT A MORE SIGNIFICANT STORM SYSTEM STILL CANNOT BE RULE OUT. HOWEVER CONFIDENCE IN A MAJOR STORM HAS LARGELY DIMINISHED SINCE YESTERDAY WITH THIS SCENARIO NOW LOOKING LIKE A LOW PROBABILITY OUTCOME. CONFIDENCE REGARDING THE STORM TRACK AND ASSOCIATED WEATHER IMPACTS HAS INCREASED SOMEWHAT (FROM LOW TO AVERAGE) GIVEN THE CONVERGENCE TOWARD A MORE COMMON SOLUTION...WITH A LIGHT RAIN/SNOW EVENT EMERGING AS THE MOST LIKELY AND PROBABLE OUTCOME. HIGH PRESSURE SHOULD PROVIDE A QUIET WEATHER PERIOD EARLY NEXT WEEK BEFORE THE PATTERN TURNS INCREASINGLY UNSETTLED AND POTENTIALLY STORMY HEADING INTO CHRISTMAS EVE/DAY.
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&& .AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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WIDESPREAD STRATO CU AND PERSISTENT MVFR TO IFR CIGS WITH ISOLATED-SCATTERED AND GENERALLY BRIEF MVFR TO IFR VSBYS IN SNOW SHOWERS WILL OCCUR ACROSS THE NW MTNS AND LAUREL HIGHLANDS /INVOF KBFD AND KJST/ THROUGH FRIDAY MORNING. CONDITIONS ACROSS THE CENTRAL MTNS AND SUSQ VALLEY WILL VARY BETWEEN LOW END VFR...AND MVFR CIGS. GUSTY WEST TO WNW WINDS /UP AROUND 25 KTS AT TIMES/ WILL ADD SOME MECHANICAL TURBULENCE DURING TAKEOFF AND FAP TO REGIONAL AIRFIELDS THIS AFTERNOON THROUGH THURSDAY. A SECONDARY COLD FRONT AND COMPACT UPPER AIR DISTURBANCE DROPPING SE ACROSS THE REGION LATE TODAY AND EARLY TONIGHT COULD BRING SOME BRIEFLY HEAVIER SNOW SHOWERS...WITH A COATING TO 1/2 INCH POSSIBLE EVEN ACROSS THE CENTRAL MTN AND SUSQ VALLEY AIRFIELDS. OTHERWISE...NOT A LOT GOING ON TILL MAYBE JUST BEFORE CHRISTMAS. THERE COULD BE WIDESPREAD RAIN SHOWER ACTIVITY AROUND AS A POTENT SFC AND UPPER LOW TRACKS NE TWD THE OHIO RIVER VALLEY. OUTLOOK... THU-FRI...MVFR CIGS POSS NW. OTHERWISE NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW/REDUCED VSBY POSSIBLE ...MAINLY ALONG THE MD BORDER. MONDAY...MAINLY VFR. HOWEVER...AREAS OF MVFR STRATO CU ARE POSSIBLE IN DEVELOPING SERLY LOW LEVEL FLOW.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...STEINBUGL AVIATION...LAMBERT

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