Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 222129 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 529 PM EDT MON SEP 22 2014 .SYNOPSIS... A LARGE AREA OF HIGH PRESSURE OVER THE MIDWEST...WILL BUILD EAST ACROSS THE MID ATLANTIC REGION TUESDAY BEFORE DRIFTING OVER THE NEW ENGLAND STATES FOR THE LATTER HALF OF THE WEEK. THIS DOMINANT WEATHER FEATURE WILL PROVIDE GENERALLY FAIR AND COOL WEATHER FOR THE ENTIRE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... DEEP...AND WELL-ALIGNED NWRLY FLOW AND ASSOCIATED LAKE EFFECT CLOUDS/ISOLATED LIGHT SHOWERS ACROSS THE ALLEGHENIES WILL CONTINUE THROUGH EARLY TONIGHT...BEFORE THE MEAN BOUNDARY LAYER FLOW GRADUALLY WEAKENS BY 5 KTS OR SO AND CONTRACTS THE CLOUD COVER BACK TWD THE SOUTH SHORE OF LAKE ERIE. THE CLOUDS WILL BE TOUGH TO BREAK UP COMPLETELY...AND BASED ON SEVERAL FACTORS INCLUDING MODEL FCST OF HIGH RH/S IN THE 925-850 MB LAYER...THE 850 MB RIDGE AXIS WELL TO THE WEST OF PENN THROUGH 12Z TUESDAY...AND ANOTHER /ALBEIT WEAKER/ 850 MB THERMAL TROUGH DRIFTING SE ACROSS LAKE ERIE IN THE 06-09Z PERIOD TUESDAY...MVFR CIGS MAY HANG ON FOR MOST OR ALL OF THE NIGHT INVOF KBFD AND POINTS WEST. LLVL TRAJECTORIES APPEAR FAVORABLE TO KEEP PLENTY OF CLOUDS ACROSS THE LAUREL HIGHLANDS AS WELL THROUGH THIS EVENING. THE THINNER...AND MAINLY BKN STRATO CU THAT WILL BE PRESENT FOR THE REST OF TODAY ACROSS THE CENTRAL AND SE ZONES SHOULD SCT OUT EARLY TONIGHT...THANKS TO THE MEAN SFC-850 MB FLOW DECREASING TO AROUND 10 KTS. TEMPS SHOULD RISE JUST ANOTHER 1-3 DEG F THIS AFTERNOON...WITH MAX TEMPS RANGING FROM 50-55F ACROSS THE NRN AND WRN MTNS...TO THE MID AND UPPER 60S THROUGHOUT THE LOWER SUSQ VALLEY. THESE READINGS WILL GIVE US AN EARLY TASTE OF AUTUMN THAT OFFICIALLY BEGINS HERE AT 0229Z TUESDAY. THE HIGHS WILL BE A SOLID 6-10F BELOW NORMAL /WITH THE GREATEST DEPARTURES OF 12-14F BELOW NORMAL ACROSS THE NW MTNS. LOW TEMPS EARLY TUESDAY WILL REACH FROSTY LEVELS ACROSS THE HIGHER TERRAIN OF SOMERSET COUNTY...WHERE A FROST ADVISORY WAS POSTED FROM 07-13Z TUESDAY. ELSEWHERE...PATCHY FROST IS POSSIBLE FOR RURAL VALLEYS...EXCEPT FOR THE LOWER SUSQ VALLEY. LOWS WILL BE IN THE U30S TO AROUND 40F IN MOST LOCATIONS THROUGHOUT THE CENTRAL RIDGE AND VALLEY REGION...WITH LOWER 40S IN THE LARGER SERN PENN METRO AREAS SUCH AS YORK...HARRISBURG...AND LANCASTER. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... HIGH PRESSURE WILL BUILD EAST FROM THE OHIO NE UP THE OHIO VALLEY AND BECOME CENTERED RIGHT OVER THE REGION TUESDAY AFTERNOON. AFTER SOME LOCALLY DENSE RIVER VALLEY FOG AND PATCHY FROST IN A FEW OF THE COLDER SPOTS EARLY TUESDAY...EXPECT ABUNDANT SUNSHINE AND LIGHT WIND FOR THE LATE MORNING AND AFTERNOON HOURS. TUESDAY WILL BE A MUCH MILDER DAY WITH TEMPS RISING ABOUT 25F DURING THE DAY...AND REACHING ABOUT 10F MILDER THAN MONDAY/S HIGHS IN THE NW - BUT STAYING SIMILAR TO MONDAY IN THE LOWER SUSQ. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... STRONG HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN THROUGH THE REST OF THE WEEK AND INTO EARLY NEXT WEEK WITH HIGHER THAN NORMAL MSLP ANOMALIES OVER THE REGION. THE MODELS ARE IN FAIR AGREEMENT THROUGH MOST OF THE PERIOD...THOUGH THEY DIVERGE THIS WEEKEND AND THROUGH NEXT WEEK. HOWEVER...ALL SOLUTIONS KEEP THE REGION DRY DUE TO A BLOCKING 500 HPA ANTICYCLONE AND DRY MIDLEVELS. THE BIG QUESTION IS THE EXTENT OF DIURNAL VALLEY FOG. EXPECT PATCHY FOG WEDNESDAY AND THURSDAY MORNINGS WITH DENSE FOG AND LOW CLOUDS POSSIBLE. THE GFS AND EC AND CANADIAN MODELS DIVERGE BUT THE NEXT CHANCE FOR PRECIPITATION SHOULD/T BE UNTIL MID TO LATE NEXT WEEK. && .AVIATION /21Z MONDAY THROUGH SATURDAY/...
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22/21Z...LATEST VISIBLE STLT TRENDS SHOW GRADUAL BREAK-UP AND DISSIPATION OF LOW SC CLOUDS FROM SE TO NW ACROSS THE AIRSPACE. EXPECT MVFR CIGS TO PERSIST THE LONGEST AT BFD WHILE JST BREAKS OUT BY LATER THIS EVE. ELSEWHERE LOW VFR DECKS WILL TREND TWD SKC. NW WINDS WILL GRADUALLY WEAKEN TNGT AS HIGH PRES BUILDS INTO THE AREA FROM THE OH VLY. MAIN CONCERN FOR THE OVERNIGHT PERIOD WILL BE LOCALLY DENSE FOG. CONFIDENCE IS LOW TO MEDIUM CONCERNING TERMINAL IMPACTS BUT GENERALLY KEPT CONTINUITY FROM PREVIOUS 18Z SCHEDULED TAFS. GENERALLY TRANQUIL WEATHER WITH MAINLY VFR CONDITIONS SHOULD PREVAIL THROUGH MUCH OF THE WEEK...WITH THE EXCEPTION OF SOME PATCHY MORNING VALLEY FOG. OUTLOOK... WED-SAT...LCL AM FOG...OTHERWISE VFR.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY FROM 3 AM TO 9 AM EDT TUESDAY FOR PAZ033. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...GRUMM/CERU AVIATION...LAMBERT/STEINBUGL

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