Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 250551 AFDCTP Area Forecast Discussion National Weather Service State College PA 151 AM EDT THU AUG 25 2016 .SYNOPSIS... A seasonably warm and humid late-summer weather pattern will continue across Central Pennsylvania through the weekend. The best chance for scattered showers or thunderstorms will come on Thursday and early next week. && .NEAR TERM /UNTIL 8 AM THIS MORNING/... Main focus early this morning is on line of showers/storms approaching from Ohio. Parent shortwave is tracking north of Lake Ontario at 05Z, so expect little in the way of lg scale forcing to support line of convection as it pushes into Central Pa later this morning. Latest HRRR supports this idea of a weakening band of showers moving into the Allegheny Plateau arnd dawn along trailing low lvl jet and assoc plume of higher PWATs. Based on latest radar trends and HRRR output, will place likely POPS across the nw mtns toward dawn, with slight chc POPS extending into the Central Mtns. Surging dwpts on southerly flow will yield a much milder night than those recently, with min temps in the mid to upper 60s most places. && .SHORT TERM /8 AM THIS MORNING THROUGH 6 PM FRIDAY/... Have further refined skycover and POPs - allowing for a dry slot behind the early morning scattered showers. However, the guidance keeps high llvl moisture (low clouds) around in the NW after the overnight/morning showers. If those NWrn areas can break out, it will likely allow some heating/instability for the aftn and evening over the NW and sct tsra have a good chc of forming in NW PA and trying to slide into the central mtns. Model CAPEs of 1000 in the NW and 1500 central areas and 06km shear of 30-40kts are respectable. However, there will be some CIN to overcome. MRGL risk seems well- placed at this point. Prev... Did adjust clouds up and temps down slightly for the daytime on Thursday. While precip still looks scattered, the initial cloud cover may delay/hinder heating. Curr POPs and timing of front looking fine. How much/strong convection will be is the question. Prev... Decaying frontal boundary will feed on 2"+ PW Thursday leading to scattered coverage of showers and thunderstorms on Thursday. Main problem may be developing sufficient CAPE as overnight convective remnants from the Ohio Valley may plague a good portion of central PA into Thu afternoon. Latest SPC Day 2 has western portion of my CWA in MRGL risk for Thu afternoon...as setup is far from ideal. Still...the moist and unstable air mass will support scattered convection ahead of the weakening front. Sfc dewpoints will make a run at or exceed 70 in many areas...so it will be noticeably stickier than Wed afternoon. Highs central and north should be a few degrees lower due to cloud cover...while southern areas will warm another degree or two over Wed highs. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... The high pressure over the southeast will weaken the trough moving through and it will become very diffuse on Friday as it slips south toward the Mason Dixon line. Temperatures and humidity will be on the rise with 90F heat likely returning to the Lower Susquehanna Valley by Friday and through the weekend. A drier air mass will reside over the area through most of Sunday. 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 /06Z THURSDAY THROUGH MONDAY/... Line of showers/storms over eastern OH should gradually weaken as it shifts ewd across the western-central airspace between 09-12z. Confidence is low in the band holding together into ZNY sector. Agree with guidance bringing a short period of low MVFR to IFR cigs into KBFD/KJST behind the line given moist low level flow ascending the higher terrain. Conditions trend to VFR into mid-day with focus shifting to potential thunderstorm impacts for the afternoon/evening. Will wait to examine the latest CAM guidance before adding mention of thunder with the 25/12z scheduled TAFs. Scattered showers remain possible tonight with some restrictions likely heading into Friday morning. Outlook... Fri...A.M. restrictions possible; becoming VFR. Isold thunderstorms possible southern 1/4 airspace in the afternoon. Sat...Patchy A.M. fog. Otherwise no sig wx expected. Sun...Isold thunderstorms possible western 1/3 airspace in the afternoon. Mon...Isold-sct thunderstorms possible. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir NEAR TERM...Fitzgerald SHORT TERM...Dangelo/DeVoir LONG TERM...Ceru/Steinbugl AVIATION...Steinbugl

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