Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 160343 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1143 PM EDT MON SEP 15 2014 .SYNOPSIS... A WEAK AREA OF LOW PRESSURE WILL MOVE EAST ACROSS THE OHIO RIVER VALLEY TONIGHT BEFORE SLIDING OFF THE DELAWARE COAST DURING THE MIDDAY HOURS TUESDAY. THIS LOW...WILL COMBINE WITH A DISTURBANCE ALOFT TO BRING NUMEROUS SHOWERS TO NORTHERN PENN OVERNIGHT...WITH SHOWERS OF THE MORE SCATTERED VARIETY OVER SOUTHERN PENN. THE REST OF THIS WEEK WILL BE MAINLY DRY AS HIGH PRESSURE BRINGS PLENTY OF SUNSHINE AND AND SLIGHTLY BELOW NORMAL TEMPERATURES TO THE AREA. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... THICKENING/LAYERED CLOUDS WILL CONTINUE TO SPREAD EAST ACROSS THE REGION OVERNIGHT. WEAK LOW PRESSURE OVER THE LOWER OHIO VALLEY /AND NEAR THE NOSE OF A SLIGHTLY ANOMALOUS...SWRLY LLJ/ WILL SLIDE JUST TO THE SOUTH OF THE STATE OVERNIGHT...WHILE BANDS OF 850-700 MB FGEN FORCING /BENEATH THE RIGHT ENTRANCE REGION OF A 115 KT JET OVER SRN ONTARIO/ MOVES ACROSS CENTRAL AND NRN PENN. A LARGE AREA OF LIGHT TO MDT SHOWERS /COVERING MUCH OF LAKE ERIE AND NRN OHIO AT 02Z/ WILL SHIFT EAST THROUGH THE OVERNIGHT HOURS AND TARGET MAINLY THE NORTHERN THIRD TO HALF OF THE STATE. 15Z AND 21Z SREF AND 18Z OPERATIONAL NAM AND GFS INDICATE BASIN AVERAGE QPF AMOUNTS OF 2-3 TENTHS ACROSS THE NRN TIER COUNTIES OF PENN. EC ENSEMBLES ALSO IMPLY QUITE A SHARP GRADIENT IN POPS FURTHER SOUTH ACROSS THE CWA - BETWEEN 1-80 AND I-70/76. HOURLY AND OVERNIGHT LOW TEMPS LOOK IN PRETTY GOOD SHAPE WITH MINS RANGING FROM 45-50F ACROSS THE NRN AND WRN MTNS...TO THE LOWER AND MID 50S ELSEWHERE. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... COLD FRONT WILL BE MOVING ACROSS THE AREA VERY FAST TUESDAY MORNING. ANY LIGHT PRECIP AFTER 12Z TUESDAY SHOULD BE CONFINED ACROSS THE REGION JUST TO THE EAST OF THE SUSQ MAINSTEM. SKIES WILL CLEAR OUT QUICKLY BY NOON IN MOST PLACES...THOUGH SOME BRIEFLY BKN...FLAT STRATO CU ARE POSSIBLE DURING THE MIDDAY AND AFTERNOON HOURS ACROSS THE NRN TIER OF PENN. HEIGHTS STAY FAIRLY HIGH...SO NOT SEEING MUCH LAKE EFFECT ACTIVITY. SOME CLOUDS EARLY ON. WIND WILL LIKELY KICK UP SOME. MAIN CONCERN WILL BE POTENTIAL FOR FROST AND FREEZING TEMPS ACROSS THE NORTH TUE NIGHT. MAV NUMBERS HAVE BFD BELOW 32. CLEAR SKIES AND LIGHT WINDS...ALONG WITH HIGH HEIGHTS AND LOW DEWPOINTS/PW VALUES SUPPORT SOME POTENTIAL FOR FROST ETC. STILL A WAYS OUT...LATER SHIFTS CAN MONITOR AND ISSUE FLAGS AS NEEDED. && .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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BY WED...SURFACE HIGH PRESSURE OVER OHIO VALLEY WITH DRIER COOLER NORTHWEST FLOW IN LOWER LEVELS. THERE MAY BE SOME CLOUDS LINGERING OVER HIGHER TERRAIN UNDER SUBSIDENCE INVERSION EARLY...BUT CENTRAL PA SHOULD SEE GOOD DEAL OF SUNSHINE OVERALL. HIGHS WILL BE ABOUT 5F BELOW NORMAL. TROUGH ALOFT SHARPENS OVER QUEBEC WED NIGHT/THU...PUSHING A WEAK FRONTAL BOUNDARY SOUTH TOWARD PA ON THU. THIS FRONT WILL CONTINUE TO WEAKEN AS IT EDGES SOUTHWARD...BUT A WEAK SHORTWAVE WILL SLIDE OVERHEAD FROM THE MIDWEST. THIS WILL BRING AN INCREASE IN CLOUDS COVER ALONG WITH JUST A CHANCE FOR A SPRINKLE. NORTHERN PA WILL GET A REINFORCING SHOT OF COOLER AIR...KEEPING HIGHS IN THE UPPER 50S TO LOWER 60S. HIGH PRESSURE THEN BUILDS ACROSS THE GREAT LAKES INTO A 1030MB HIGH OVER NEW ENGLAND BY FRI...BRINGING A PERIOD OF QUIET WEATHER AND UNSEASONABLY COOL TEMPERATURES. MORNING LOWS IN THE 30S ARE LIKELY THU NIGHT IF SKIES CLEAR OUT AS ANTICIPATED. HIGHS ON FRI WILL BE MAINLY IN THE 60S AS NW FLOW CONTINUES. RETURN FLOW BEGINS WEAKLY FRI NIGHT...TAKING A LITTLE OF THE BITE OUT OF OVERNIGHT LOWS /THOUGH STILL CHILLY WITH READINGS MAINLY IN THE 40S/. BUT THIS WILL BEGIN A WARMING TREND FOR THE WEEKEND. TEMPS SAT INTO SUN WILL BE 5-8F WARMER THAN FRI...WITH HIGHS APPROACHING 80F IN THE SE. LOWS WILL BE NOTICEABLY MILDER AS WELL AS LOW LEVEL MOISTURE INCREASES IN STRENGTHENING SW FLOW. HEADING INTO SUNDAY...DEEPENING LOW CENTERED WELL TO OUR NORTH AS A TROUGH AXIS ROTATES THROUGH THE GREAT LAKES WILL BRING PLENTY OF CLOUDS AND A CHANCE FOR SHOWERS. MODELS STILL SHOWING LARGE DIFFERENCES ON EVOLUTION OF THIS SYSTEM...WITH GFS MORE PROGRESSIVE AND ECMWF ACTUALLY BRINGING A SECOND WAVE AROUND THE BACKSIDE OF THE TROUGH AND DEVELOPING A STUBBORN CLOSED UPPER LOW OVER THE REGION. FOR NOW WILL SPLIT THE DIFFERENCE AND HOLD ON TO MENTION OF SHOWERS INTO MON ALONG WITH ANOTHER SHOT OF COOLER AIR AND SEE HOW THIS PLAYS OUT OVER NEXT COUPLE OF DAYS.
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&& .AVIATION /04Z TUESDAY THROUGH SATURDAY/...
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AREA OF SHOWERS MOVING INTO NWRN PA ATTM. ARE FAIRLY LIGHT BUT WILL LEAD TO SOME GRADUAL REDUCTIONS ESP ACROSS NWRN AIRFIELDS EARLY THEN CENTRAL AND SRN OVERNIGHT. CONDITIONS SHOULD BECOME VFR BY MID TO LATE MORNING ON TUESDAY...AS THE COLD FRONT MOVES EAST OF THE AREA. IT WILL BE BREEZY AT TIMES ON TUE. SOME POTENTIAL FOR FOG TUESDAY NIGHT...AS HIGH PRESSURE BUILDS OVER THE AREA. MAINLY DRY CONDITIONS THE REST OF THE WEEK...AS HIGH PRESSURE PREVAILS. OUTLOOK... WED-SAT...MAINLY VFR CONDITIONS.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT/MARTIN NEAR TERM...LAMBERT/MARTIN SHORT TERM...LAMBERT LONG TERM...RXR AVIATION...GARTNER/MARTIN

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