Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 251601 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1101 AM EST TUE NOV 25 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD NORTHEAST FROM THE OHIO RIVER VALLEY TODAY WITH FAIR AND COOLER CONDITIONS. A STORM SYSTEM WILL FORM ALONG THE SOUTHEASTERN COASTLINE OF THE UNITED STATES AND MOVE UP ALONG OR JUST OFF THE EASTERN SEABOARD WEDNESDAY...BRINGING A CHANCE OF SIGNIFICANT SNOW TO SOUTHERN AND EASTERN PA WEDNESDAY. ANOTHER SHOT OF COLDER AIR WILL FOLLOW FOR NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE CONTINUES TO SHOWS SHIELD OF MID-HIGH CLOUDS RACING NE OVER THE REGION IN RESPONSE TO A SHEARING OUT SHORTWAVE EMBEDDED IN THE FAST SWLY FLOW ALOFT. REGIONAL RADAR SHOWS THAT PRECIP IS REMAINING WELL SOUTH AND EAST OF THE LOCAL AREA. FOR TODAY WEAK RIDGE OF HIGH PRESSURE NOSING IN FROM THE OHIO VALLEY. COLD AIR STRATOCU WORKING INTO THE NW MTNS...WITH SCT CLOUDS STRETCHING FROM KJST-KUNV-KIPT. TRICKIER CLOUD FORECAST IN THE SE WITH HIGH CLOUDS STREAMING OVERHEAD IN FAST SW FLOW ALOFT...BUT TRICK IS THE OPACITY OF THE CLOUDS. APPEARS THAT THEY WILL REMAIN THIN ENOUGH IN MOST PLACES TO KEEP PARTLY SUNNY WORDING FOR THIS AFTERNOON. COLD AIR GRADUALLY FILTERING IN FROM THE WEST TODAY...AND KBFD ALREADY PUSHING TO TODAYS FCST HIGHS...SO BUMPED THE NW MTNS UP A COUPLE OF DEGREES BEFORE TEMPS LEVEL OFF. SE LOOKS BASICALLY ON TARGET WITH MILD HIGHS PEAKING MAINLY IN THE MID 50S. MODELS ARE IN GOOD AGREEMENT TO DEVELOP A NEW STORM ALONG THE GA/SC COAST IN RESPONSE TO A POTENT SHORTWAVE APPROACHING FROM THE MISSISSIPPI VALLEY. THE SYSTEM ALOFT TAKES ON A NEG TILT AS IT MOVES UP THE EASTERN SEABOARD...WITH THE SURFACE LOW MADE TO TRACK ALONG THEN JUST OFFSHORE OF THE EAST COAST WEDNESDAY. TIMING SUGGESTS PRECIP OVERSPREADING THE SOUTHERN TIER COUNTIES BEFORE DAYBREAK WEDNESDAY. TEMPS ALOFT AND ON THE SURFACE SUGGEST THAT PRECIP STARTING OVER SOUTHERN AREAS LATER TONIGHT WILL LIKELY BE AT LEAST A MIX OF RAIN AND SNOW WITH LIGHT SNOW ON THE NORTHERN EDGE. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... THE MAIN SHOW WILL OCCUR WEDNESDAY AS THE STORM DEVELOPS AND INTENSIFIES AS IT TRACKS FROM THE CAROLINA COAST TO OFF THE NJ COAST BY WED EVENING. THE TRACK IS CLOSE ENOUGH TO PLACE MY EASTERN ZONES UNDER THE THREAT FOR WARNING CRITERIA SNOWS...WITH AMOUNTS OF 3-6" POSSIBLE EVEN BACK INTO THE LAURELS. AS A RESULT I EXTENDED THE WATCH TO INCLUDE SOMERSET AND CAMBRIA COUNTIES...GIVEN THE EXPECTATIONS OF A HIGH IMPACT SNOWFALL ON A WHAT IS TRADITIONALLY ONE OF THE MOST HEAVILY TRAVELED DAYS OF THE YEAR. LATEST WWD GRAPHICS SHOW A SWATH OF 6-8 SNOWS OVER THE SERN 1/3 OR SO OF MY FCST AREA. THIS IS NOT SIGNIFICANTLY DIFFERENT THAN THE SREF THREAT PAGE THAT SHOWS A SIMILAR ORIENTATION OF WARNING SNOWS FROM THE NRN PART OF THE STATE INTO MY SOUTH-CENTRAL MOUNTAINS...NUDGING SOMERSET AND CAMBRIA COUNTIES. I USED A BLEND OF MODEL QPF WHICH FAVORS SERN ZONES WITH HIGHEST AMOUNTS...WHICH MAKES SENSE GIVEN THE EXPECTED TRACK JUST OFFSHORE RATHER THAN CLOSER TO THE COAST WHICH IS PREFERABLE FOR LOCAL SNOW CROWS. I TRIED TO SIMILARLY PAINT THE BEST CHANCE OF WARNING SNOWS OVER THIS SERN 1/3 OR SO BACK INTO THE AREAS FAVORED BY THE SREF THREAT PAGE AND WWD FORECAST. I`M NOT AS CONFIDENT ABOUT SIG SNOWS UP INTO CENTRAL PA GIVEN THE LACK OF A SIG EASTERLY LOW LEVEL WIND ANOMALY IN THE ENSEMBLES...BUT FOR IMPACTS I CAN SEE AN ADVISORY BEING NEEDED SO NO CHANGES WERE MADE TO THE WATCH ON THE NORTHERN EDGES. && .LONG TERM /THURSDAY THROUGH MONDAY/... A SHOT OF COLD AIR WILL MOVE INTO THE REGION FOR THE HOLIDAY AND CONTINUE THROUGH FRIDAY. THIS SHOULD GENERATE THE USUAL POST FRONTAL LAKE AND OROGRAPHICALLY ENHANCED SNOW SHOWERS IN THE WAKE OF THE DEPARTING STORM SYSTEM WITH WESTERN AND NORTHERN AREAS SEEING THE BEST CHANCE OF SCATTERED LIGHT SNOWS...WHILE THE REST OF THE REGION SEES LITTLE OR NO SNOW SHOWER ACTIVITY AT ALL. A BROAD WSW FLOW ALOFT WILL MAKE THE NEXT COLD SHOT TEMPORARY WITH WARMER AIR BEGINNING TO MAKE A RETURN BY SATURDAY. HIGHS WILL RETURN TO NEAR OR EVEN A TICK ABOVE NORMAL BY THE WEEKEND BEFORE COOLER AIR APPROACHES AGAIN FOR EARLY NEXT WEEK. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... WHEN I DID THE 18Z TAFS YESTERDAY...WAS CONCERN ABOUT LOWER SC INTO BFD. BEEN SOME IN BFD THE LAST FEW HOURS...BUT THEY ARE ON THE EASTERN EDGE. DID HAVE SOME AT JST. CENTRAL AREAS HAVE BKN250...WHILE AREAS TO THE EAST AND SOUTH HAVE A THICKER CI DECK. WILL ADJUST 15Z TAFS AS NEEDED...BUT MOST OF THE AREA WILL BE VFR FOR MUCH OF THE DAY. EARLIER DISCUSSION BELOW. VFR WILL CONTINUE THROUGH THE FIRST HALF OF THIS EVENING. CONDITIONS WILL DETERIORATE LATE TONIGHT AND THROUGH WEDNESDAY. EXPECT MVFR CONDITIONS TO BEGIN THROUGH THE SOUTHEAST...AFFECTING MDT AND LNS BETWEEN 06Z TO 12Z AND SPREADING NORTHWARD. A SMALL BAND OF RAIN COULD OCCUR ON THE ONSET OF THE SYSTEMS ARRIVAL...BUT SWITCH QUICKLY OVER TO SNOW. IFR RESRECTIONS SHOULD BE POSSIBLE AT ALL TAF SITES EXCEPT BFD...WHICH WILL REMAIN VFR UNTIL THE SYSTEM CREEPS NORTHWARD WEDNESDAY AFTERNOON. REDUCED CIGS AND VSBYS WILL CONTINUE INTO WEDNESDAY EVENING. OUTLOOK... THU...AM FOG POSS SOUTH. EVENING -SHSN/REDUCED VSBYS POSS W MTNS. FRI-SAT...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR PAZ019-042-045-046-049>053. WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY EVENING FOR PAZ024>028-033>036-056>059-063>066. && $$ SYNOPSIS...LA CORTE/RXR NEAR TERM...LA CORTE/RXR SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...FITZGERALD/CERU/MARTIN

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