Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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172 FXUS61 KCTP 270921 AFDCTP Area Forecast Discussion National Weather Service State College PA 521 AM EDT Thu Jun 27 2024 .SYNOPSIS... Partly to mostly sunny and less humid for today and Friday. A return of summertime heat and humidity will fuel thunderstorms for the last Saturday of June followed by improving conditions Sunday into Monday with unseasonably cooler and dry weather to start the month of July. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A secondary push of cooler and drier air will move Southeast across the region this morning. Variable amounts of clouds this morning will give way to increasing increasing sunshine this afternoon. PWAT will dive to around 0.6-0.7 of an inch over much of the region by later today or about -1 sigma. Highs today will be in the low to mid 70s over the higher terrain of the north and west and low to mid 80s in the Central and Southern Valleys. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... High pressure near Chicago late this afternoon will build to the east and become centered over Western New York and Northwestern Pennsylvania tonight with clear skies, cool temperatures and light wind, leading to the formation of valley fog given moist ground from yesterdays widespread convection and air/water T spreads 20-30 degrees. Lows tonight will vary from the chilly mid and upper 40s across the Northern Mountains to the upper 50s and low 60s in the Southern Valleys. Partly cloudy and slightly warmer conditions are likely Friday, as low pwats persist over PA and a return southerly flow develops as the surface high passes off the coast. Latest model data suggests some showers and storms may develop Friday night over the western portion of the forecast area. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Latest medium range guidance is showing an unusual lack of spread among its members, all of which track a surface low north of PA Saturday, with a trailing cold front coming through Sat night into early Sunday. The lack of spread with regards to timing of the front, combined with progged GEFS pwats of +2-3SD, supports an increasing confidence in showers/tsra Saturday. A leading warm front could produce showers/tsra as early as Friday night and a slowing cold front could cause convection to linger into Sunday, mainly over the southeast counties. However, ensemble plumes indicate the most widespread convection should occur Sat afternoon and evening. There is some potential for severe wx Saturday PM, as decent mid level flow overspreads an increasingly moist warm sector. Ensemble plumes currently indicate moderate CAPE in the 1000 J/kg range and model 0-6km shear is in the 35-40kt range. If the cold front slows enough, severe wx would also be possible across the eastern edge of the forecast area Sunday PM. Latest EPS and GEFS both support fair weather with near to slightly below normal temps and low humidity early next week associated with high pressure building east from the Grt Lks. A seasonably cool and dry start to July! && .AVIATION /09Z THURSDAY THROUGH MONDAY/... Widespread low stratus has developed across northwestern PA including the Alleghenies. IFR conds are likely at BFD and JST, with LIFR possible between 09z and sunrise. Downslope flow and some wind will probably keep IPT/UNV/AOO from getting as bad (low) of conditions overnight. But, some IFR is possible at those locations, too (less than a 50% chc), and fog can not be ruled out at MDT and LNS if the midlevel clouds move out before sunrise. All TAF sites will be VFR by mid morning Thursday. Winds will remain from the NW with gusts generally less than 20 kts. Outlook... Fri...Generally VFR. Sat-Sun...Thunderstorm impacts possible. Mon...Generally VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert SHORT TERM...Lambert LONG TERM...DeVoir/Steinbugl AVIATION...Dangelo/Colbert