Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 241048 AFDCTP Area Forecast Discussion National Weather Service State College PA 648 AM EDT WED AUG 24 2016 .SYNOPSIS... A seasonably warm and humid late-summer weather pattern will continue across Central Pennsylvania through the weekend. The most likely periods for thunderstorms are Thursday and early next week. && .NEAR TERM /THROUGH TONIGHT/... Minor update to hourly temperatures. Valley fog will dissipate by 8-9am. High pressure retreating off the Northeast coast will ensure another dry day with southerly return flow bringing warmer temperatures and a gradual uptick in dewpoints/humidity levels. Forecast maximum temperatures this afternoon are running about 5 degrees above normal for late August. Multi-model/high resolution ensemble blend still highlights NW PA to the west of US-219 with max POPs /20-40 percent/ in the 00-12z Thursday period. The risk for showers is coincident with surge of theta-e/warm advection and moisture flux on nose of 20-30kt WSW LLJ. Milder overnight readings in the low-mid 60s. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... A closed 594DM upper high initially centered over the Deep South will slowly migrate northeastward into the southern Mid Atlantic by the end of the period. A de-amplifying shortwave trough moving through Ontario/Quebec will send a cold front through the Lower Lakes on Thursday. The front is forecast to weaken as it continues to push southeast encountering the building ridge aloft. A moist and unstable airmass will reside in advance of the weakening cold front which should prove favorable for the development of isolated to scattered convection from the OH Valley into western PA during the afternoon/evening hours. SPC D2 MRGL remains focused from the OH Valley into far western PA where the strongest mean wind fields are projected. The front/sfc trough becomes very diffuse on Friday as it slips south toward the Mason Dixon line. Weak instability and rich boundary layer moisture in advance of the weak front/sfc trough supports maintaining very low tstm probs /20 pct or less/ primarily across the southern 1/2 to 1/3 of the CWA. However, this may be overdone given increasing large scale subsidence and falling PWATs. Temperatures and humidity will be on the rise with 90F heat likely returning to the Lower Susquehanna Valley by Friday. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The deep-layer ridge will gradually slide off the Mid Atlantic coast this period, which allows another frontal boundary to sink southward from the Lower Lakes and become quasi-stationary over PA early next week. This will favor unsettled conditions Mon-Tue with POPs trending upward following a mainly dry weekend. Temps will remain above normal by late August standards. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Expect VFR conditions early this morning to give way to some areas of MVFR and local IFR conditions in fog. Morning fog will give way to another VFR day on Wednesday. Approaching front with increased moisture could bring a chance of TSRA on Thursday, mainly in the west. Outlook... Wed...Patchy AM fog possible, otherwise VFR. Thu...Generally VFR, but with Isold pm tsra impacts possible, mainly w mtns. Fri...Morning low cigs possible across the Western Mountains, otherwise VFR. Sat-Sun...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Steinbugl AVIATION...Jung/Gartner

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