Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 301157 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 757 AM EDT THU OCT 30 2014 .SYNOPSIS... HIGH PRESSURE OVER THE OHIO VALLEY THIS MORNING WILL MOVE INTO THE APPALACHIANS TONIGHT. A VIGOROUS UPPER LEVEL TROUGH DIGGING THROUGH THE CAROLINAS WILL SUPPORT THE DEVELOPMENT OF A STRONG COASTAL STORM TRACKING JUST EAST OF THE NEW ENGLAND BENCHMARK THIS WEEKEND. THIS WILL LEAD TO A BRISK NORTH NORTHWEST WIND WITH MUCH COLDER AIR SUPPORTING SNOW SHOWERS OVER THE WESTERN ALLEGHENIES SATURDAY NIGHT. HIGH PRESSURE WILL RETURN TO THE AREA BEHIND THE DEPARTING STORM SYSTEM ON MONDAY WITH MODERATING TEMPERATURES INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... PATCHY DENSE FOG OVR PORTIONS OF THE LOWER SUSQ VALLEY SHOULD LIFT OVER THE NEXT 1-2 HOURS AS A LIGHT NW WIND ADVECTS DRIER AIR INTO THE AREA. COOL AIR SPREADING DOWNWIND OF THE LOWER GREAT LAKES ALONG WITH WEAK UPSLOPE FLOW IS SUPPORTING AN EXPANSIVE AREA OF STRATOCU CLOUDS ACROSS THE NW ALLEGHENIES. THESE CLOUDS WILL PREVAIL THROUGH THE MORNING AS THE LLVL MSTR GETS TRAPPED UNDER THE SUBSIDENCE INVERSION ASSOCIATED WITH SFC HIGH MIGRATING SLOWLY EWD FROM THE OH VLY. MDL DATA SUGGESTS BINOVC THIS AFTN WHICH MAY BE A LITTLE TOO OPTIMISTIC. DOWNSLOPE FLOW SHOULD LEAD TO MORE SUN EAST OF THE ALLEGHENY FRONT. SHORTWAVE RIDGING ALOFT AND HIGH PRES AT THE SFC WILL COMBINE TO BRING DRY WX TO CENTRAL PA FROM THIS AFTN INTO TONIGHT. HIGH TEMPS WILL RANGE FROM THE MID 40S IN THE NW TO NEAR 60F IN THE LWR SUSQ. AMPLIFYING UPPER TROUGH PIVOT INTO THE UPPER GREAT LAKES BY 12Z FRI WITH A SFC LOW DEVELOPING NEAR LAKE HURON. MDL CONSENSUS SUPPORTS A SCHC OF SHOWERS OVER FAR NW PA BY THE END OF THE PD. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... ALL MEDIUM RANGE GUIDANCE STILL SHOWS A POTENT SHORTWAVE DIVING SE THRU THE GRT LKS AND CARVING OUT A DEEP TROUGH OVR THE NORTHEAST CONUS BY FRI NIGHT. TRACK OF THIS FEATURE NOW APPEARS RELATIVELY CERTAIN BASED ON LACK OF SPREAD IN MDL RUNS...ALL OF WHICH INDICATE A PATH ACROSS EASTERN OHIO FRIDAY PM. BEST LG SCALE FORCING OVR PA...AS IMPLIED BY MDL 300-500MB Q-VEC CONVERGENCE...SHOULD BE ACROSS THE WESTERN HALF OF THE STATE. LATEST GEFS/SREF OUTPUT SUPPORT CATEGORICAL POPS ACROSS THE ALLEGHENY PLATEAU FRI AFTN/FRI NIGHT AND ONLY CHC POPS ACROSS THE SUSQ VALLEY. LACK OF DEEP MOISTURE SHOULD RESULT IN FAIRLY LIGHT RAINFALL WITH THIS FEATURE...PERHAPS UP TO A QUARTER INCH OVR THE W MTNS. RISK OF SNOW OVR THE ALLEGHENIES FRIDAY NIGHT APPEARS LOW GIVEN LATEST OPER MDL SOUNDINGS...AS WELL AS GEFS/SREF PROBS. HAVE REMOVED CHC OF SNOW AND RAISED OVERNIGHT LOWS TO ABOVE FREEZING EVERYWHERE FRI NIGHT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... ALL MED RANGE GUIDANCE CUTS OFF UPPER LOW SOUTH OF PA SATURDAY. REMNANTS OF ASSOC CLIPPER LOW SHOULD DIE OVR THE CENTRAL APPALACHIANS AS ENERGY IS TRANSFERRED TO DEVELOPING COASTAL LOW NR CAPE HATTERAS. AS COASTAL STORM LIFTS NE...A TIGHTENING PRESSURE GRADIENT AND NW FLOW WILL DRAW MUCH COLDER/DRIER AIR INTO PA. OPERATIONAL RUNS AND NEARLY ALL ENSEMBLE MEMBERS KEEP COASTAL LOW FAR ENOUGH OUT TO SEA TO NOT DIRECTLY IMPACT CENTRAL PA. HOWEVER...COLD NW FLOW WILL LIKELY PRODUCE SCT LAKE EFFECT SNOW SHOWERS ACROSS THE ALLEGHENY PLATEAU SATURDAY NIGHT. GIVEN DRYNESS OF AIR MASS MOVING IN...DON/T EXPECT ANY SIG ACCUMS...BUT A COATING OF SNOW DOES APPEAR POSSIBLE OVR THE W MTNS. TEMPS THIS WEEKEND WILL ALMOST CERTAINLY BE THE COLDEST YET THIS SEASON. ENSEMBLE MEAN 8H TEMPS POINT TOWARD DAYTIME HIGHS FROM THE U30S-L40S OVR THE ALLEGHENIES TO 45-50F ACROSS THE LOWER SUSQ VALLEY. THE COLDEST NIGHT OF THIS OUTBREAK WILL LIKELY BE SUNDAY NIGHT...WHEN SFC HIGH BUILDS OVR THE REGION. THOSE LOCATIONS THAT HAVE YET TO SEE A FREEZE WILL LIKELY GET IT BY MONDAY AM. HIGH CONFIDENCE IN A PERIOD OF DRY WEATHER SUNDAY/MONDAY...WHEN ALL GUIDANCE BUILDS SFC HIGH AND ASSOC DRY AIR MASS ACROSS PA. AN APPROACHING COLD FRONT WILL BRING THE NEXT CHC OF SHRA BY MIDWEEK. DEEP UPPER TROF WILL LIFT OUT QUICKLY EARLY NEXT WEEK...ALLOWING A MUCH MILDER RETURN SW FLOW TO OVERSPREAD THE REGION. TEMPS LIKELY TO RETURN TO ABV NORMAL READINGS BY TUESDAY. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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DENSE FOG HAS FINALLY SCOURED OUT AT LNS WITH A RETURN TO VFR EXPECTED BY 13Z. OUTSIDE CHANCE BFD/JST MAY DIP TO IFR CIG BUT DECIDED TO GO WITH PREVAILING LOW MVFR WITH THE 12Z ISSUANCE BASED ON PERSISTENCE AND GUIDANCE. HIGH CONFIDENCE IN MVFR CIGS PREVAILING OVER THE WRN 1/3 OF THE AIRSPACE EARLY TODAY WITH CIGS REMAINING AOB 050 FOR MUCH OF PERIOD. SCT-BKN LOW VFR CIGS WILL BE ACROSS THE CENTRAL AND ERN SXNS OF THE AIRSPACE THROUGH THE AFTERNOON WITH LAYERED MID AND HIGH CLOUDS INCREASING LATE TONIGHT INTO FRIDAY. OUTLOOK... FRI...VFR/MVFR EARLY WITH RAIN SHOWERS DEVELOPING WRN SXNS BY EVE. REDUCED CONDS LKLY FRI NIGHT WEST-CENTRAL 1/2 OF AIRSPACE WITH RAIN SHOWERS MIXING WITH/CHANGING TO SNOW SHOWERS WESTERN 1/3. SAT...MVFR/IFR WITH SCATTERED RAIN/SNOW SHOWERS WEST. VARYING CONDS FROM VFR-MVFR CENTRAL/EAST WITH OCNL -SHRA. N-NW WIND GUSTS 25-40 MPH. SUN...RAIN/SNOW SHOWERS ENDING WEST. LOW CIGS WEST BECOMING VFR. GUSTY NNW WINDS GRADUALLY DECREASING AREA-WIDE. MON...VFR.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD/STEINBUGL SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...STEINBUGL

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