Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 260554 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1254 AM EST WED NOV 26 2014 .SYNOPSIS...
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LOW PRESSURE FORMING OFF THE SOUTHEAST COAST WILL DEEPEN SIGNIFICANTLY AS IT MOVES NORTHEASTWARD ALONG THE EAST COAST ON WEDNESDAY...BRINGING SIGNIFICANT SNOW TO MUCH OF CENTRAL PENNSYLVANIA. ANOTHER SHOT OF COLDER AIR WILL FOLLOW FOR THE END OF THE WEEK...BEFORE TEMPERATURES MODERATE OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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MESO ANAL AT MIDNIGHT SHOWS THE LOW FORMING JUST OFF THE GA COAST. MODELS AGREE IN TRACKING THE STORM UP ALONG THEN OFF THE NJ COAST BY 100 MILES OR SO. THIS SHOULD ASSURE A WIDESPREAD MODERATE TO HEAVY SNOW OVER MUCH OF EASTERN PA WITH SIG ACCUMS ALL THE WAY BACK INTO CENTRAL AREAS. HAVE MADE NO CHANGES TO THE UPDATE PACKAGE. INITIAL THOUGHTS FOR THE NEXT UPDATE ARE THAT WE WILL BE HARD PRESSED TO REACH WARNING SNOW AMOUNTS OVER OUR VERY SERN COUNTIES WHERE A RAIN-SNOW MIX COULD LAST A WHILE. HOWEVER I WILL NOT CHANGE THE WARNING CONFIGURATION DUE TO EXPECTED IMPACT ON THE HEAVY HOLIDAY TRAVEL. FROM EARLIER... LITTLE CHANGE TO THE GOING FORECAST THIS EVENING. HIGH PRESSURE CENTERED ALONG THE IL/IN BORDER BUILDING EASTWARD THROUGH THE OHIO VALLEY WITH RIDGE AXIS EXTENDING NEWD ALONG THE LAKE ERIE SHORELINE TO LAKE ONTARIO. STRATUS IS PACKED AGAINST THE ALLEGHENIES OVER NORTHWEST PA. MID AND HIGH CLOUDS HAVE OVERTAKEN THE REMAINDER OF CENTRAL PA THIS EVENING...AND WILL BE THICKENING AS THE NIGHT WEARS ON. TEMPERATURES HAVE FALLEN TO THE LOWER 30S IN MOST PLACES AND WILL DROP A FEW MORE DEGREES ACROSS THE NORTH. STAGE IS SET FOR A LIGHT TO MODERATE SNOWFALL ACROSS A GOOD PART OF CENTRAL AND EAST CENTRAL PA. MINOR ADJUSTMENTS TO SNOWFALL MAP THIS EVENING FOR QUICKER EXIT OF SNOWFALL WEDNESDAY AFTERNOON... AND SLIGHTLY LESSER QPF ALONG THE WESTERN EDGE OF THE WARNINGS. HRW-ARW SUGGESTS ACCUMULATING SNOWFALL IS OVER BY 21Z...EVEN ACROSS THE EAST...AND IS THE MOST AGGRESSIVE IN PUSHING THE ACCUMULATING SNOWFALL OUT OF MY CWA WED AFTERNOON. HAVE NUDGED THINGS IN THAT DIRECTION...AS OTHER GUIDANCE IS ALSO FASTER...BUT MAINTAINED A BLEND OF GUIDANCE MID TO LATE AFTERNOON. FOR THE OVERNIGHT...PRECIP OVERSPREADING THE SOUTHERN TIER COUNTIES QUICKLY AFTER 08Z...WITH QPF APPROACHING A TENTH OF AN INCH BY 12Z. TEMPS ALOFT AND ON THE SURFACE SUGGEST THAT PRECIP STARTING OVER SOUTHERN /ESPECIALLY SE/ AREAS LATE TONIGHT WILL LIKELY BE AT LEAST A MIX OF RAIN AND SNOW WITH LIGHT SNOW ON THE NORTHERN EDGE. SIMPLY...PRECIP WILL MOVE INTO SOUTHERN HALF OF CWA BEFORE SUNRISE AND WILL BE LIGHT...BUT QUICKLY INTENSIFY DURING THE MORNING RUSH HOUR ACROSS THE SOUTH.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... WINTER STORM WARNINGS/ADVISORIES NOW IN EFFECT. A LOW PRESSURE SYSTEM DEVELOPS AND INTENSIFIES AS IT TRACKS FROM THE CAROLINA COAST AT 12Z WED TO OFF THE NJ COAST BY 00Z THU... BRINGING BIGGEST IMPACTS TO CENTRAL PA DURING THE DAY WED. CONFIDENCE IS GROWING IN THE STORM TRACK WITH GFS COMING IN LINE WITH THE ECMWF CLOSER TO THE COAST...WHICH WILL PUSH THE QPF SHIELD A BIT FURTHER WEST. PRECIP WILL BE ONGOING IN THE SOUTH BY SUNRISE...AND SPREADING QUICKLY INTO THE CENTRAL AND NORTHEAST BY MID MORNING. ANY RAIN WILL QUICKLY CHANGE TO SNOW IN THE SE AS COLUMN COOLS. PERIOD OF HEAVIEST INTENSITY PRECIP WILL BE WED MORNING THROUGH MID AFTERNOON...WHERE SNOW RATES COULD BE 1-2 INCHES PER HOUR IN THE WARNING AREA. LATEST WWD GRAPHICS CONTINUE TO SHOW A SWATH OF 6-8 SNOWS OVER THE SERN 1/3 OR SO OF MY FCST AREA. CONFIDENCE FOR SIG SNOWS UP INTO CENTRAL/NW PA NOT AS HIGH GIVEN THE LACK OF A SIG EASTERLY LOW LEVEL WIND ANOMALY IN THE ENSEMBLES...AND A SHORTWAVE SLIDING IN FROM THE WEST WHICH MAY SHARPEN GRADIENT OF SNOW. BUT FOR A COUPLE INCHES OF SNOW AND IMPACTS ON THE BUSIEST TRAVEL DAY OF THE YEAR WE STRUNG AN ADVISORY OVER THE NORTHERN EDGE OF THE WARNING AREA. SNOW SHOULD TAPER OFF QUICKLY BY LATE WED AFT/WED EVE AS STORM QUICKLY MOVES INTO NEW ENGLAND. FLOW TRANSITIONS BACK TO A NW FETCH ACROSS THE LAKES...WITH LIGHT SCT SNOW SHOWERS POSS BY THU MORNING IN THE UPSLOPE OF THE WESTERN HIGHER TERRAIN. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... UPPER TROFFING OVER THE EASTERN THIRD OF THE COUNTRY AT THE START OF THE LONG TERM PERIOD IS FORECAST TO FLATTEN OUT INTO AN EXTENSIVE WEST TO EAST ZONAL FLOW PATTERN COVERING MUCH OF NORTH AMERICA. HEIGHTS OVER THE NORTHEASTERN U.S. ARE THEN FORECAST TO RISE FROM LATE IN THE WEEKEND ONWARD AS THE CABOOSE IN THE CURRENT SHORTWAVE TRAIN EXITS THE EAST COAST ON FRIDAY AND ENERGY APPROACHING THE PACIFIC COAST CLOSES OFF AND BUILDS HEIGHTS OVER THE WESTERN AND CENTRAL U.S. A SHOT OF COLD AIR WILL MOVE INTO THE REGION FOR THURSDAY AND FRIDAY BEHIND THE AFOREMENTIONED CABOOSE SHORTWAVE. THIS WAVE MAY ALSO SUPPORT AN AREA OF PCPN MOVING WEST TO EAST ACROSS THE STATE THANKSGIVING DAY. ADDITIONALLY...THIS PUSH OF ENERGY/COLD AIR 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 ASSOCIATED WITH THE RISING HEIGHTS WILL MAKE THIS 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. A FRONTAL SYSTEM IN ADVANCE OF THE WARM AIR WILL MOVE ACROSS THE STATE ON SUNDAY...BRINGING THE BEST CHANCE OF PCPN DURING THE PERIOD. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... 26/03Z UPDATE...MINOR CHANGES TO ONSET OF PCPN. PROJECTED ONSET MAY BE A BIT FAST WITH THE LATEST HRRR FAVORING THE 12-15Z WINDOW ACROSS THE SRN AIRFIELDS. MDL SOUNDINGS AND HIGH RES GUIDANCE STILL SHOW RELATIVELY QUICK CHANGEOVER FROM RAIN-TO-SNOW OVER THE SE TERMINALS WITH ALL SNOW PTYPES EXPANDING NWD TO FIG-IPT LINE BY 15Z. FINALLY...BFD REMAINS ON EDGE OF LOW CLOUDS AND MVFR CIGS ACROSS NE OH/NW PA INTO WRN NY. 26/00Z...LOW PRESSURE DEVELOPING OFF THE SOUTHEAST COAST LATE TONIGHT WILL STRENGTHEN AS IT LIFTS NWD JUST OFF THE EAST COAST THROUGH WED NGT. EXPECT RAPIDLY DETERIORATING CONDS FROM SOUTH TO NORTH DURING THE PREDAWN AND EARLY MORNING HOURS AS SNOW OVERSPREADS THE AIRSPACE. PCPN WILL LKLY BEGIN AS A MIX IN THE MDT/LNS AREA BEFORE CHANGING TO ALL SNOW. MOST INTENSE SNOWFALL RATES AND REDUCED VSBYS WILL BE OVER THE SERN AIRSPACE WITH RATES UP TO 2"/HR WITH FLGT CATS AOB AIRFIELD MINS. HIGH CONFIDENCE IN WIDESPREAD IFR CONDS DUSK-DAWN BEFORE SNOW ENDS FROM SW TO NE BY WED NGT. LOW CIGS SHOULD PERSIST OVER THE WRN 1/3 OF THE AREA WED NGT WITH MARGINAL IMPROVEMENT ELSEWHERE. OUTLOOK... THU...IFR/MVFR WITH OCNL -SHSN WRN 1/3. VFR TO MVFR CIGS CNTRL/EAST. FRI...AM MVFR/-SHSN NW...OTHERWISE BCMG VFR. SAT-SUN...MAINLY VFR. -SHRA PSBL. && .CTP WATCHES/WARNINGS/ADVISORIES...
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WINTER STORM WARNING UNTIL 4 AM EST THURSDAY FOR PAZ019-042- 045-046-049>053. WINTER WEATHER ADVISORY UNTIL 4 AM EST THURSDAY FOR PAZ012-017- 018-037-041. WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR PAZ024>028- 033>036-056>059-063>066.
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&& $$ SYNOPSIS...LA CORTE/STEINBUGL NEAR TERM...DEVOIR/LA CORTE SHORT TERM...RXR LONG TERM...LA CORTE/GARTNER AVIATION...STEINBUGL

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