Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 221454 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1054 AM EDT MON SEP 22 2014 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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FIRST BOUT OF COLD SEASON LAKE EFFECT CLOUDS AND SHOWERS IN FULL SWING ACROSS THE NRN AND WRN MTNS OF PENN...THANKS TO DELTA LAKE-850 MB TEMPS AROUND 20C AND A DEEP... WELL-ALIGNED NWRLY FLOW ACROSS LAKE ERIE AND THE LONG AXIS OF LAKE HURON. THE CLOUDS WILL BE TOUGH TO BREAK UP...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...IT SHOULD STAY OVERCAST FOR AT LEAST THE FIRST HALF /IF NOT ALL/ OF THE NIGHT TONIGHT ACROSS THE NW MTNS. LLVL TRAJECTORIES APPEAR FAVORABLE TO KEEP PLENTY OF CLOUDS ACROSS THE LAUREL HIGHLANDS AS WELL. 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 VEERING AROUND TO THE NNW AND DECREASING TO AROUND 10 KTS. MAX TEMPS TODAY WILL RANGE FROM THE L-M 50S 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. THERE WILL BE A FEW...THIN STREAMERS OF SHOWERS DRIFTING OFF LAKE ERIE AND CROSSING THE NW MTNS AND LAUREL HIGHLANDS...SO WE MAINTAINED THE 20-30 POPS IN THOSE AREAS TODAY. NOTHING MORE THAN A FEW BRIEF SPRINKLES WILL OCCUR NEAR...AND JUST TO THE SE OF THE ALLEGHENY FRONT.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
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HIGH PRESSURE NOSES IN FROM THE MIDWEST AND BE RIGHT ABOUT OVERHEAD BY TUESDAY EVENING. 8H TEMPS WILL ALREADY BE RISING TONIGHT. CLEARING IS EXPECTED FOR MUCH OF THE AREA...BUT SOME REINFORCEMENT TO THE CLOUDS MAY COME DOWN FROM THE NORTH LATE TONIGHT/TUESDAY MORNING. REFER TO THE ABOVE /NEAR TERM SECTION/ FOR ADDITIONAL DETAILS ON THE CLOUD TRENDS TONIGHT. THE SHALLOW COLD AIR AND INVERSION WILL LET THE WINDS GO CALM AND TEMPS COULD DROP INTO THE M/U30S IN THE HIGHER ELEVATIONS. EMPLOYING SOME OF THE COLDER MODEL SOLUTIONS WHERE SKIES DO CLEAR OUT TONIGHT AND WINDS LIGHTEN...WILL MENTION PATCHY FROST WITH MIN TEMPS IN THE MID 30S. HOWEVER...A TRUE CONSENSUS ALL/MODEL BLEND APPROACH TO OUR TEMP GRIDS TONIGHT AND EARLY TUESDAY WOULD YIELD MINS IN THE UPPER 30S TO AROUND 40F WITH LITTLE OR NO CONCERN FOR FROST. A BETTER BET IS THAT SOME VALLEY FOG WILL FORM IN THE DEEPER/DARKER VALLEYS BY SUNRISE TUES AS THE TEMPS FALL WELL BELOW THE WATER TEMPS. THE COLDER SPOTS IN THE EASTERN VALLEYS WILL ALSO DROP OFF NEAR 40F BY MORNING. TUESDAY WILL BE A MUCH MILDER DAY WITH TEMPS RISING ABOUT 25F DURING THE DAY AND REACHING ABOUT 10F MILDER THAN MONDAY IN THE NW - BUT STAYING SIMILAR TO MONDAY IN THE LOWER SUSQ.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGH PRESSURE WILL PARK ITSELF OVER NEW YORK AND NEW ENGLAND WITH +2 TO +3 SIGMA ABOVE NORMAL MSLP ANOMALIES BY WEDNESDAY-THURSDAY. THE MODELS SEEM TO BE IN FAIR AGREEMENT SHOWING A BLOCKING 500 HPA ANTICYCLONE TO THE NORTHWEST AS A MASSIVE 500 HPA POSITIVE HEIGHT ANOMALY OF +2 TO +3 SIGMA DEVELOPS OVER CENTRAL CANADA BY THURSDAY AND INTO FRIDAY. THE MODELS AND ENSEMBLE MEANS DO WELL FORECASTING ANTICYCLONES SO THERE SEEMS TO BE MORE OF A CONSENSUS ON THE FAIR WEATHER FORECAST NEXT WEEK. EXPECT DIURNAL VALLEY FOG AND LOW CLOUDS LIKELY TO AFFECT THE REGION EACH MORNING ONCE THE BIG HIGH TAKES HOLD....AND CONTINUING DAILY INTO NEXT WEEKEND. THAT MASSIVE HIGH SHOULD CONTINUE THE DRY FAIR WEATHER THROUGH NEXT WEEKEND. && .AVIATION /14Z MONDAY THROUGH FRIDAY/...
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EXTENSIVE CLOUD DECK CONTINUES TO COVER WESTERN AND CENTRAL AREAS LATE THIS MORNING. IN THE WESTERN AND NORTHERN MOUNTAINS... WIDESPREAD MVFR TO IFR CIGS ARE IN PLACE. OVER CENTRAL AIRFIELDS...MVFR CIGS PREVAIL. OVER EASTERN AREAS...VFR CONDITIONS CAN BE FOUND WITH DOWNSLOPING LEADING TO A HIGHER...SCT-BKN CLOUD BASE. RADAR CONTINUES TO SHOW SEVERAL NARROW...STREAMERS OF LIGHT PCPN ACROSS WESTERN AND CENTRAL AREAS OF THE STATE. WIDESPREAD NATURE OF CLOUDS WILL MEAN THAT THEY WILL LINGER ACROSS THE WEST WELL INTO THE AFTERNOON...BEFORE DRIER AIR...SURFACE RIDGING...AND MIXING HELP TO BREAK THESE UP ACROSS THE SE HALF OF THE STATE TONIGHT. THE WELL-ALINGED AND DEEP NWRLY FLOW WILL HELP TO MAINTAIN THICKER STRATO CU ACRS THE NW MTNS...AND TO A SLIGHTLY LESSER DEGREE OVER THE LAUREL HIGHLANDS. GENERALLY TRANQUIL WEATHER WITH MAINLY VFR CONDITIONS SHOULD PREVAIL TUESDAY THROUGH WED...WITH THE EXCEPTION OF SOME PATCHY MORNING FOG. OUTLOOK... TUE-FRI...MAINLY VFR...BUT WITH DAILY RESTRICTIONS IN MORNING FOG POSSIBLE.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...LAMBERT SHORT TERM...DANGELO LONG TERM...GRUMM/CERU AVIATION...JUNG/LAMBERT

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