Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 242144 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 444 PM EST MON NOV 24 2014 .SYNOPSIS... A COLD FRONT WILL PASS THROUGH THIS EVENING AND EARLY TONIGHT. AN AREA OF LOW PRESSURE WILL MOVE NORTHWARD ALONG THE EAST COAST...BRINGING A CHANCE OF SIGNIFICANT SNOW TO THE EASTERN HALF OF PENNSYLVANIA ON WEDNESDAY. ANOTHER SHOT OF COLD AIR WILL FOLLOW FOR NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... FRONT APPEARS TO BE THROUGH KCLE AND ALMOST TO WRN PA. GUSTS ALONG THE FRONT AND IN SOME OF THE SHOWERS AHEAD OF IT ARE UP TO 40KTS AND EXPECT THESE GUSTS TO TRANSLATE TO THE EAST AS THE SHOWERS PASS. THEREFORE...WILL CONTINUE THE WIND ADVY AS IS. IT MAY BE CHOPPED EARLIER THAN CURR EXP TIME AS DECOUPLING SHOULD HELP. TEMPS VERY CLOSE TO RECORD MAXES THIS AFTN...BUT ARE STRUGGLING AS THE MIXING IS ALREADY PRETTY DEEP AND SUN ANGLE IS LOWERING. FRONT SHOULD MOVE TO THE EAST BY MIDNIGHT/2 AM...AND OVERNIGHT TEMPS BEHIND THE FRONT WILL GET COLD ENOUGH FOR SOME SHSN IN THE NWRN FEW COS. BUT OTHER AREAS WILL PROBABLY STAY ABOVE FREEZING. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... STRONG CAA ON TUESDAY AS A MINOR HIGH PRESSURE BUILDS IN FROM THE W/SW. CLOUDS AND SCT SHSN IN THE FAR NW WILL KEEP TEMPS VERY COOL...AND THEY MAY NOT RISE AT ALL IN THE NW. BUT THE REST OF THE STATE WILL HAVE MORE SUNSHINE AND THE SE WILL GET SOME DOWNSLOPING. EVEN SO...DIURNAL RANGES OF 10F ARE ABOUT ALL THAT THE SE WILL MANAGE ON TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
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POTENTIAL FOR SIG WINTER IMPACTS FROM LOW PRESSURE MOVING UP THE EAST COAST ON WED/WED NIGHT. WILL CONTINUE TO INJECT INTERPRETATION OF THE LATEST MODEL GUIDANCE WITH EACH 3-HOURLY UPDATE TO GUIDE DECISION SUPPORT LEADING UP TO THE PRIME TRAVEL PERIOD FOR THE THANKSGIVING HOLIDAY. FOCUS IN LONG TERM CONTINUES TO BE POTENTIAL FOR SIG IMPACTS FROM A LOW PRESSURE SYSTEM QUICKLY DEEPEING AND SLIDING UP THE EAST COAST ON WED. TROUGH SLIDING THROUGH CENTRAL U.S. TODAY WILL SWING TOWARD THE EAST COAST AS A WAVE OF LOW PRESSURE IS BORN OVER FLORIDA ON TUES. THE LOW WILL DEEPEN AS IT TRACKS NORTHWARD JUST OFF THE EASTERN SEABOARD...PASSING BY THE NJ COAST BY 00Z THU AS A STILL DEEPENING 998MB LOW. FORECAST CONFIDENCE IN DEVELOPMENT OF THIS LOW REMAINS VERY HIGH...WITH FAIR AMOUNT OF UNCERTAINTY PERSISTING IN EXACT TRACK OF THE LOW WHICH WILL IMPACT ASSOCIATED SNOW/RAIN AMOUNTS. THE TAKEAWAY FROM THE 12Z MODEL SUITE IS THAT THE WESTWARD DRIFT OF THE TRACK EVIDENT IN DATA OVER THE PAST SEVERAL DAYS HAS STOPPED...WITH ECMWF CONTINUING TO FORECAST THE TRACK WEST OF THE GFS/GEFS. VARIATIONS IN QPF FIELDS CONTINUE...BUT SETTLING IN ON AROUND A QUARTER INCH FROM KJST-KIPT TO CLOSER TO 0.75 IN THE LOWER SUSQ VALLEY. PRECIP SHOULD SLIDE IN FROM THE SOUTH BEFORE SUNRISE ON WED AS WEAK HIGH PRESSURE LIFTS NORTHWARD AS STORM APPROACHES. NORTHERLY FLOW OVER CENTRAL PA NOT PARTICULARLY STRONG IN ANY MODEL...BUT A SHORTWAVE LOOKS POISED TO SLIDE IN FROM THE GREAT LAKES ON WED TO ADD SOME SYNOPTIC LIFT TO THE RAPIDLY DEEPENING AND FAST MOVING SURFACE LOW. AIR MAY BE WARM ENOUGH AT ONSET IN FAR SE COUNTIES TO BEGIN PRECIP AS RAIN OR A MIX OF RAIN/SNOW. BUT COOLING OF THE COLUMN WILL CHANGE PRECIP OVER TO ALL SNOW...WITH HIGHEST TOTALS MOST LIKELY EAST OF A KAOO-KUNV-KIPT LINE WHICH LOOKS TO INCLUDE THE HARRISBURG METRO AREA. ENOUGH CONFIDENCE AT THIS POINT FOR A HIGH IMPACT EVENT /ON THE BUSIEST TRAVEL DAY OF THE YEAR/ TO ISSUE A WATCH FOR SE HALF OF CWA. BIGGEST IMPACTS WILL BE POTENTIAL FOR A SEVERAL HOUR PERIOD OF HEAVY ACCUMULATING SNOW DURING THE DAY WED. BUT AGAIN...SMALL CHANGES IN THE ULTIMATE TRACK COULD LEAD TO MODIFICATIONS OF SNOWFALL FORECASTS. THE TAKE AWAY...THOUGH THE DETAILS REMAIN FLUID...THERE WILL BE SIG IMPACTS TO TRAVEL ALONG THE U.S. EAST COAST ON ONE OF THE BUSIEST DAYS OF THE YEAR /WED/. PLAN ACCORDINGLY. COLDER AIR REMAINS IN PLACE LATE IN THE WEEK AS SCT SNOW SHOWERS RETURN TO THE WESTERN HIGHER TERRAIN. TEMPS LOOK TO GRADUALLY MODIFY STARTING THIS WEEKEND HEADING INTO NEXT WEEK AS MID LEVEL FLOW FLATTENS AND THEN BROAD RIDGE DEVELOPS OVER EASTERN 2/3 OF U.S. WE COULD BE BRUSHED BY A COUPLE WEAK SYSTEMS...BUT NO ADDITIONAL BIG STORM SYSTEMS EXPECTED AFTER THANKSGIVING.
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&& .AVIATION /21Z MONDAY THROUGH SATURDAY/... DEEP SYSTEM LIFTING NE. STRONGEST WIND FIELDS LIFT NE THIS AFT. TOOK OUT LLWS. MAIN CONCERN IS LINES OF SHOWERS TO THE WEST. WILL CONTINUE TO MONITOR...NO THUNDER AT THIS PT. NOT REAL COLD ALOFT...THUS NOT CONCERN ABOUT DAMAGING WINDS AT THIS TIME. WINDS WILL WEAKEN OVERNIGHT. DID NOT WEAKEN THEM TOO MUCH. SHOULD THE WIND DIE AT SPOTS LIKE IPT...MDT...AND LNS... THEN FOG COULD BE AN ISSUE. EXPECT DRIER AIR TO THE WEST. LOOKING AT VFR CONDITIONS INTO EARLY TUE AFT...GIVEN DIRECTIONAL SHEAR AND LIMITED COLD AIR. MAIN CONCERN WILL BE WED...PERIODS OF WET SNOW EXPECTED...AS A COMPLEX LOW LIFTS NE. OUTLOOK... TUE...NO SIG WX EXPECTED. WED...SNOW/LOW VSBYS POSS EASTERN PA. THU...-SHSN/REDUCED VSBYS POSS NW MTNS. FRI...NO SIG WX EXPECTED. SAT...NO SIG WX EXPECTED...AS HIGH PRESSURE BUILDS IN. && .CTP WATCHES/WARNINGS/ADVISORIES...
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WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR PAZ019-042-045-046-049>053. WIND ADVISORY UNTIL 4 AM EST TUESDAY FOR PAZ004>006-010-011- 017-024-033. WINTER STORM WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY EVENING FOR PAZ025>028-034>036-056>059-063>066.
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&& $$ SYNOPSIS...DANGELO NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...RXR AVIATION...MARTIN

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