Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 250948 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 448 AM EST TUE NOV 25 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD NORTHEAST FROM THE OHIO RIVER VALLEY TODAY WITH FAIR AND COOLER CONDITIONS. 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 THE SOUTHERN AND EASTERN PA WEDNESDAY. ANOTHER SHOT OF COLDER AIR WILL FOLLOW FOR NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE SHOWS A 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 WE WILL SEE A WEAK RIDGE OF HIGH PRESSURE NOSE IN FROM THE OHIO VALLEY. I WENT FOR PARTLY TO MOSTLY SUNNY SKIES BUT WILL NOT BE SURPRISED IF A FAIR AMOUNT OF HIGH CLOUDINESS PREVAILS AS WE STAY UNDER A FAST SWLY FLOW ALOFT. IT`S GOING TO TAKE A WHILE FOR THE COLD AIR TO FILTER IN TODAY...SO MUCH OF THE SERN HALF OF MY FCST AREA WILL REMAIN UNSEASONABLY MILD IN THE MID TO UPPER 50S...WHILE THE NW WILL BE COOLER IN THE 30S. 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 /09Z TUESDAY THROUGH SATURDAY/... GUSTY WINDS HAVE RETURNED DUE TO THE STRONG WEST TO NORTHWESTERLY FLOW. GUSTY WINDS AT UNV...BFD SHOULD CONTINUE . CAN/T RULE OUT A PERIOD OF MVFR CIGS AT KBFD LATE TONIGHT INTO EARLY TUE MORNING. HOWEVER...MDL SOUNDINGS NOT MAKING A CONVINCING CASE FOR IT. HIGH CONFIDENCE IN WIDESPREAD VFR CONDS HOLDING THRU TUESDAY...AS A RIDGE OF HIGH PRESSURE AND DRY AIR WORK IN FROM THE OHIO VALLEY. ONLY POSSIBLE EXCEPTION WOULD BE KBFD...WHERE OROGRAPHIC LIFT COULD CONCEIVABLY SUPPORT OCNL MVFR CIGS...MAINLY TUESDAY MORNING. OUTLOOK... WED...SNOW/LOW VSBYS SOUTHEAST HALF OF PA. 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 NEAR TERM...LA CORTE SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...FITZGERALD/CERU

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