Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 241258 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 758 AM EST SAT JAN 24 2015 .SYNOPSIS... LOW PRESSURE NEAR THE DELMARVA PENINSULA THIS MORNING WILL TRACK QUICKLY NORTHEAST TODAY. AN ALBERTA CLIPPER WILL TRACK JUST SOUTH OF PENNSYLVANIA SUNDAY NIGHT WITH ANOTHER WEAKER CLIPPER TAKING THE SAME PATH MONDAY NIGHT AND EARLY TUESDAY. HIGH PRESSURE WILL BUILD OVER THE REGION MID WEEK...FOLLOWED BY ANOTHER CLIPPER LATE THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... REGIONAL RADAR INDICATING DIMINISHING PRECIP RATES AT 09Z...AS LL JET AND ASSOC STRONGEST FORCING SHIFTS OFF THE E COAST. HOWEVER...LIGHTER PRECIP ASSOC WITH PASSAGE OF MID LVL SHORTWAVE WILL CONTINUE TO FALL OVR MUCH OF CENTRAL PA THRU THIS MORNING...AND INTO THE AFTN OVR AREAS EAST OF THE SUSQ RIVER. SFC OBS AT 09Z INDICATE THE RAIN/SNOW LINE RUNS FROM KHGR NEWRD THRU KMDT. MDL SOUNDINGS IMPLY PTYPES SOUTH OF THIS LINE WILL WAVER BTWN SNOW/RAIN TODAY. REGARDLESS...EXPECT LITTLE IF ANY ADDITIONAL SNOW ACCUM FROM SOUTH OF HARRISBURG...BASED ON MARGINAL BLYR TEMPS. FURTHER NORTH...UPSTREAM RADAR TRENDS AND MDL QPF SUPPORT PERHAPS AN ADDITIONAL INCH OF SNOW BTWN 5 AM AND NOON. WILL MOST LIKELY BE ABLE TO CANCEL EXISTING WARNINGS/ADVISORIES EARLY...AS ROAD CONDS IMPROVE LATER THIS AM. NW FLOW IN WAKE OF THIS SYSTEM SHOULD BRING PARTIAL CLEARING THIS AFTN TO AREAS EAST OF THE ALLEGHENIES. HOWEVER...A FAST MOVING AND WEAK CLIPPER TYPE SHORTWAVE WILL BE DIVING INTO THE REGION FROM THE GRT LKS TOWARD EVENING...LIKELY SPREADING -SHSN ACROSS THE ALLEGHENY PLATEAU TOWARDS DUSK. THE AIR MASS BEHIND TONIGHT/S LOW IS NOT PARTICULARLY COLD AND ENS MEAN 925 TEMPS SUPPORT HIGHS TODAY IN THE M/U30S OVR MUCH OF THE AREA...WHICH SHOULD RESULT IN MUCH IMPROVED ROAD CONDS BY AFTN. ACROSS THE ALLEGHENY PLATEAU...UPSLOPING FLOW AND RESIDUAL LOW LVL MOISTURE WILL LIKELY RESULT IN PERSISTENT STRATOCU ALL DAY...HOLDING TEMPS JUST BLW FREEZING. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... PASSAGE OF SHORTWAVE THIS EVENING SHOULD PRODUCE -SHSN ACROSS THE ALLEGHENY PLATEAU WITH A SMALL ACCUM OF AN INCH OR LESS. LATE TONIGHT...SHORTWAVE PASSES EAST OF THE STATE...CAUSING -SHSN TO TAPER OFF OVR THE NW MTNS. HOWEVER...RESIDUAL UPSLOPE FLOW INTO THE LAURELS WILL KEEP THE -SHSN GOING DOWN THERE. A DOWNSLOPING WEST WIND SHOULD RESULT IN NOTHING MORE THAN FLURRIES EAST OF THE MTNS TONIGHT. WIDESPREAD STRATOCU SHOULD HOLD READINGS UP TONIGHT WITH LOWS IN THE 20S. SOME LIGHT OROGRAPHIC SNOW MAY BE ONGOING SUNDAY MORNING ACROSS THE LAUREL HIGHLANDS. HOWEVER...MAIN FOCUS WILL BE ON POTENT ALBERTA CLIPPER DIVING INTO THE OHIO VALLEY. BLEND OF MED RANGE GUIDANCE SUPPORTS A GOOD CHANCE OF SNOW OVERSPREADING AT LEAST THE SOUTHWEST QUARTER OF THE STATE BY EVENING. A BIT OF SUN APPEARS POSSIBLE ACROSS NE PA ON SUNDAY. OTHERWISE...PLENTY OF MID LVL CLOUDINESS INDICATED BY MDLS IN ADVANCE OF CLIPPER. CONSALL MAX TEMPS RANGE FROM THE L20S NW MTNS...TO THE U30S S OF HARRISBURG. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MDL SPREAD DECREASING/CONFIDENCE INCREASING WITH RESPECT TO TIMING/TRACK OF CLIPPER SUNDAY NIGHT. HAVE THEREFORE RAMPED UP THE CHANCE OF SNOW ACROSS THE ENTIRE REGION...WITH CATEGORICAL POPS ACROSS THE LAURELS/SC MTNS. PLENTY OF COLD AIR AVAILABLE AND EXPECT NO PRECIP TYPE ISSUES WITH THIS EVENT. ADDITIONAL SHORTWAVE AND ASSOC WEAKER CLIPPER IS PROGGED TO TAKE A SIMILAR PATH SOUTH OF PA MON NIGHT/EARLY TUESDAY...LIKELY CAUSING OCNL LIGHT SNOW TO LINGER INTO TUESDAY. BLEND OF ENSEMBLE AND OPER MDL QPF IS POINTING TOWARD AN ADVISORY TYPE SNOWFALL ATTM ACROSS THE LAUREL/SC MTNS SUN NITE/MON AM...WITH LIGHTER ADDITIONAL ACCUMS LIKELY FROM SECOND CLIPPER MON NITE/TUE AM. COLDEST AIR OF THE WEEK DIVES IN BEHIND THE DEPARTING SYSTEM ON TUESDAY WITH STATEWIDE HIGHS A FEW DEGREES EITHER SIDE OF 20F. AS SFC HIGH BUILDS OVR THE AREA TUE NIGHT...CLEARING SKIES...A CALM WIND AND FRESH SNOW COVER COULD RESULT IN AN IDEAL RADIATIONAL COOLING SCENARIO WITH SUB-ZERO LOWS POSSIBLE IN MANY LOCATIONS. MODERATING CHILL IS IN STORE FOR THE MID TO LATE WEEK...AS RIDGING AT THE SURFACE AND ALOFT MOVES IN AHEAD OF NEXT IN SERIES OF ALBERTA CLIPPERS. DECENT AGREEMENT AMONG MED RANGE GUIDANCE WITH TIMING OF THIS NEXT CLIPPER...SO HAVE INCREASED CHC OF LGT SNOW LATE THU/THU NIGHT. LONGER RANGE OUTLOOK FEATURES NO RESPITE FROM THE COLD WX...WITH ECENS INDICATING A DEEPENING TROUGH OVR THE EASTERN CONUS. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/... LOW PRESSURE NEAR THE DELMARVA PENINSULA THIS MORNING WILL TRACK QUICKLY NORTHEAST TODAY. AN ALBERTA CLIPPER WILL TRACK JUST SOUTH OF PENNSYLVANIA SUNDAY NIGHT WITH ANOTHER WEAKER CLIPPER TAKING THE SAME PATH MONDAY NIGHT AND EARLY TUESDAY. THE MODERATE TO HEAVY SNOW AND SOME LIGHTER FREEZING RAIN IN THE LOWER SUSQ IS QUICKLY WINDING DOWN AS LOW PRESSURE QUICKLY MOVES TO THE NORTHEAST. BUT IFR/LIFR CIGS WILL LINGER. ONE LAST BAND OF LIGHT SNOW WILL REDUCE VSBYS FOR A SHORT TIME AS IT SLIDES EASTWARD...THEN IMPROVEMENTS TO CIGS WILL BEGIN LATE THIS MORNING AND EARLY AFTERNOON FOR THE CENTRAL AND EASTERN SECTIONS AS CIGS RISE TO MVFR AND EVENTUALLY TO VFR. IN THE WESTERN HIGHER TERRAIN...IMPROVEMENT WILL NOT BE QUITE AS ROBUST WITH CIGS LIKELY ONLY LIFTING TO MVFR AND MAYBE A SHORT PERIOD OF VFR. WINDS WILL SHIFT TO THE WEST AND PICK UP A BIT LATE IN THE DAY AS LOW LEVEL FLOW INCREASES...PUSHING WINDS TO AROUND 10-15 MPH IN THE WEST. STRONGER LOW LEVEL WESTERLY FLOW WILL KEEP WINDS UP AROUND 10-15 MPH IN THE WESTERN HIGHER TERRAIN TONIGHT...WITH 850MB WINDS INCREASING TO 35-45 KTS OVER THE SW HALF OF CWA...SO ADDED MENTION OF LLWS THERE. THIS IS ASSOCIATED WITH A WEAK SHORTWAVE THAT WILL ALSO SPAWN LIGHT SNOW SHOWERS WITH VSBY REDUCTIONS TONIGHT IN SAME AREA. COULD BE AN OCCASIONAL ENCROACHMENT INTO THE CENTRAL MTNS OF MVFR CIGS...WHILE SOUTHEAST REMAINS VFR. A PROLONGED PERIOD OF RESTRICTIONS LIKELY SUNDAY NIGHT INTO MON NIGHT AS ANOTHER CLIPPER LOW MOVES THROUGH. OUTLOOK... SUN...VFR INTO THE AFTERNOON...THEN SNOW DEVELOPING ACROSS THE WEST IN THE AFTERNOON OR EVENING...AND OVERSPREADING ALL OF CENTRAL PENN AND THE SUSQ VALLEY AT NIGHT. MON...AM SNOW WITH WIDESPREAD MVFR TO IFR LIKELY. TUE-WED...NO SIG WEATHER EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR PAZ019-024-025-033-042-045-046-064>066. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR PAZ026>028-034>036-049>053-056>059-063. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/GARTNER AVIATION...RXR

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