Area Forecast Discussion
Issued by NWS State College, PA

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019 FXUS61 KCTP 231028 AFDCTP Area Forecast Discussion National Weather Service State College PA 628 AM EDT Tue May 23 2017 .SYNOPSIS... Rain should pass to the southeast of the area later today and tonight. The most likely period for rain in Central PA will be Wednesday night into Thursday. The weather pattern will be unsettled into the holiday weekend with a few opportunities for rain through Memorial Day. Seasonal temperatures will trend a bit cooler with rain expected late-week, with a modest rebound likely into the weekend. && .NEAR TERM /THROUGH TONIGHT/... Dense fog has dissipated over the LSV as of 10z. Beautiful sunrise locally with a pink and purple hues illuminating layer of bkn-ovc cirrus. Perusal of later arriving HIRES data including HRRR suggesting perhaps a slightly better chance for rain to reach/crossover the Mason-Dixon line around 00z and have adjusted POPs accordingly. Overall, expect most of the area to remain dry through tonight with greatest risk for light pcpn south of PA Turnpike closest to MD border. Broad SW flow in advance of deep trough/closed low dropping south from MN to MO will provide steady stream of high clouds which may end up shaving a few degrees off of max temps. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... The deep closed low evolves slowly east from the Mid MS Valley across the Central Appalachians Wed-Thu with complex surface low occlusion over the OH Valley and secondary development from the Mid Atlantic Piedmont to the New England coast by 26/12z. Despite differences in QPF, the models generally agree with the most likely period of rain from Wed ngt-Thu. Total rain amounts for the 24hr period ending 00z Fri are 0.50-1" and derived from a multi-model/WPC blend. Rain should turn more showery Thu ngt into Friday under cyclonic flow aloft. Temps trend cooler with expected clouds and rain. && .LONG TERM /FRIDAY THROUGH MONDAY/... Cool cyclonic flow on backside of departing cyclone will maintain risk for showers on Friday. A lower-amplitude mid level flow pattern will develop into the weekend with some ridging likely at 500mb. Uncertainty regarding location and timing of shortwave impulses rounding the ridge and effect of prior upstream convection leaves plenty of question marks for Saturday - but there is some agreement in area of max POPs over S OH/into WV and SW PA. NBM/ECE blend yielded the highest POPs for Sunday across Central PA associated with cold front moving south/eastward across the Great Lakes/Appalachians. A severe risk may accompany the cold front but still to early for details. The large scale pattern evolves into a broadly cyclonic regime into early next week around an upper low between the Great Lakes and Hudson Bay. This should keep the pattern unsettled with another round of showers/Tstorms possible next Tuesday. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... Fog starting to thin out. 09Z TAFS adjusted for this and sent. Any fog across eastern PA will burn off just after sunrise. Most of the day will feature just some high clouds. Perhaps some light rain late, but mainly south of the TAF sites, based on the airmass in place and guidance keeping most of the area dry. Wed morning may feature more fog and low clouds, given that fcst lows are at or below fcst dewpoints, cross over temperatures. Still time to look this over, as it would be mainly after 06Z. Another factor will be that the high clouds could cut down on the cooling late Tuesday and early Wed. .OUTLOOK... Wed...Evening rain/low cigs possible, esp JST/AOO. Thu...Rain/low cigs likely. Fri...Showers/MVFR cigs NW. VFR SE. Sat...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Steinbugl AVIATION...Fitzgerald/Martin

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