Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 182132 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 532 PM EDT THU SEP 18 2014 .SYNOPSIS... A TROUGH OF LOW PRESSURE OVER EASTERN NORTH AMERICA WILL SLOWLY WEAKEN INTO SATURDAY BEFORE RE-INTENSIFYING LATER ON SUNDAY. OVERALL IT SHOULD BE A RELATIVELY COOL AND DRY PERIOD WITH A BRIEF WARM UP EXPECTED OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... FAIR WEATHER CU SHOULD DISSIPATE QUICKLY THIS EVENING IN THE FAIRLY DRY AIRMASS ACROSS THE REGION. MOISTURE-LIMITED COLD FRONT ACROSS SRN NY STATE THIS AFTN HAS MADE ONLY SLOW PROGRESS SWD DURING THE DAY TODAY. THE FRONT IS FORECAST TO THE STATE LATE THIS AFTERNOON AND EVENING. GENERALLY FAIR WEATHER CU WILL BE THE RULE THIS AFTERNOON IN THE COOL AND DRY AIRMASS REMAINING OVER THE STATE. TONIGHT WILL BY QUITE COLD WITH SCATTERED FROST POSSIBLE ACROSS THE COLDEST VALLEYS ALONG THE NORTHERN PA BORDER. CLOUDS ASSOCIATED WITH THE FRONTAL BOUNDARY MAY HOWEVER LINGER ALONG THE NRN BORDER. ALSO..WITH THE SFC HIGH PRESSURE CENTER LOCATED NORTH OF PA...ENOUGH EASTERLY GRADIENT MAY REMAIN TO KEEP WINDS FROM GOING CALM. CURRENT GUIDANCE CONTINUES TO INDICATE BORDERLINE TEMP/DEWPOINTS FOR WIDESPREAD FROST UP NORTH ATTM...BUT GIVEN THE MENTIONED UNCERTAINTY AND AFTER COORDINATION WITH SURROUNDING WFOS...HAVE DECIDED TO RUN WITH THE MENTION OF SCATTERED FROST IN THE CURRENT FORECAST. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... AS HIGH PRESSURE CENTER MOVES EAST OF THE NEW ENGLAND COAST FRIDAY...SFC WINDS WILL TURN SERLY/SRLY HELPING DAYTIME TEMPS TO RISE A FEW DEGREES HIGHER THAN TODAY. OTHERWISE EXPECT CONTINUED RAIN FREE..MOSTLY SUNNY EARLY FALL-FEELING DAY ACROSS CENTRAL PA. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... WARMER AIR AND HIGHER MOISTURE WILL ADVECT INTO THE REGION THIS WEEKEND ON INCREASING SW FLOW AROUND A HIGH PRESSURE AREA /RETREATING TO THE EAST/. AT THE SAME TIME...SHORTWAVE DROPPING OUT OF CANADIAN ROCKIES WILL BEGIN TO CARVE OUT A TROUGH OVER THE GREAT LAKES AS DEVELOPING SYSTEM APPROACHES PA FOR SUN/MON. THE INITIAL RESULT WILL BE A PAIR OF ABOVE NORMAL TEMPERATURE DAYS SAT-SUN WITH TEMPS MAINLY IN THE 70S...AND TAKING A RUN AT 80F IN THE SE. WE/LL ALSO GET A BREAK FROM OUR RUN OF CHILLY OVERNIGHTS AS LOWS REMAIN IN THE 50S FRI NIGHT TO AROUND 60F SAT NIGHT. A PERIOD OF LOW/STRATUS AND PATCHY DRIZZLE IS POSSIBLE FOR A FEW HOURS EARLY SATURDAY AS A WARM FRONTAL BOUNDARY SLIDES NORTHWARD...OTHERWISE SHOWER ACTIVITY SHOULD REMAIN CONFINED TO THE UPPER MIDWEST THROUGH EARLY SUNDAY. THE CENTER OF THE APPROACHING LOW PRESSURE SYSTEM WILL REMAIN WELL TO OUR NORTH...BUT A WEAK COLD FRONT WILL PUSH THROUGH PA SUNDAY INTO SUN NIGHT. THIS WILL BE THE BEST CHANCE OF RAIN/SHOWERS THROUGH DURATION OF THE EXTENDED FORECAST. THE LATEST ECMWF/GFS GENERALLY AGREEING ON POTENTIAL FOR A TENTH TO POTENTIALLY A QUARTER OF AN INCH OF QPF. THE 500 HPA TROUGH BEHIND THE FRONT BOTTOMS OUT OVER THE REGION MONDAY. THIS WILL KEEP MENTION FOR SCT INSTABILITY SHOWERS...MAINLY IN HIGHER TERRAIN OF N/W CWA. COOLER AIR ON NW FLOW WILL GRADUALLY FILTER BACK INTO THE REGION...WITH MONDAY/S HIGHS ABOUT 8-10F COOLER AND TUESDAY SLIPPING ANOTHER COUPLE OF DEGREES AS TROUGH LIFTS AWAY TO THE NE. LOOKS LIKE LOWS IN THE MID/UPPER 30S AGAIN BECOME LIKELY ACROSS THE NORTHERN MTNS FOR MIDWEEK AS LARGE AREA OF HIGH PRESSURE SETTLES IN OVER NEW ENGLAND. TEMPS WILL GRADUALLY WARM HEADING INTO NEXT WEEKEND. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... A COLD FRONT...LOCATED ALONG THE NY/PA BORDER AT 21Z...WILL PUSH SOUTH THROUGH PENNSYLVANIA THIS EVENING. DUE TO A LACK OF DEEP MOISTURE...THE FRONT WILL PRODUCE NO PRECIP AND EVEN THE SCT CU OBSERVED AT 21Z SHOULD DISSIPATE TOWARD SUNSET. THE MAIN AVIATION CONCERN LATER TONIGHT WILL BE THE POSSIBILITY OF LOW CIGS DEVELOPING OVR THE ALLEGHENY PLATEAU...THE RESULT OF RELATIVELY MOIST EASTERLY FLOW ASCENDING THE HIGHER TERRAIN OF CENTRAL PA. A PATCH OF LOWER CIGS ARE NOTED ACROSS WESTERN NY STATE AT 21Z IN WAKE OF COLD FRONT AND NEAR TERM MDL DATA SUGGESTS THESE CLOUDS COULD SPREAD INTO KBFD LATE THIS EVENING...AND EVEN POSSIBLY KJST LATE TONIGHT. ALTHOUGH SOME PATCHY FOG IS CERTAINLY POSSIBLE LATE TONIGHT...PRES GRADIENT SUGGESTS A NERLY BREEZE WILL MAKE WIDESPREAD VIS RESTRICTIONS UNLIKELY. ANY EARLY LOW CIGS ACROSS THE W MTNS SHOULD MIX OUT SHORTLY AFTER SUNRISE FRIDAY. ALL MODEL DATA THEN SUPPORTS A HIGH CONFIDENCE FCST OF VFR CONDS FOR THE REST OF THE DAY...AS HIGH PRES RIDGE COVERS THE AREA. OUTLOOK... SAT...AM LOW CIGS/FOG POSSIBLE. SUN...SLIGHT CHC OF PM TSRA IMPACTS W MTNS. MON-TUE...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GARTNER NEAR TERM...GARTNER SHORT TERM...LAMBERT/GARTNER LONG TERM...RXR AVIATION...FITZGERALD/GARTNER

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