Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 250927 AFDCTP Area Forecast Discussion National Weather Service State College PA 527 AM EDT THU AUG 25 2016 .SYNOPSIS... A seasonally warm and humid late-summer weather pattern will continue across Central Pennsylvania into next week. Scattered thunderstorms with strong wind gusts are possible in the Northwest Alleghenies later this afternoon into the evening. && .NEAR TERM /THROUGH TONIGHT/... Line of showers associated with pre-frontal trough will move across the Alleghenies early this morning before weakening to the east of RT 219/I-99. Followed the recently upgraded HRRR very closely through late morning which seemed to have a good handle on the current/evolving radar trends. Used a blend of convective- allowing models (CAMs) for the remainder of the near term period which resulted in max POPs over the NW Alleghenies during the late afternoon into early evening. This area is included in the MRGL severe Tstom risk outlook from SPC. In the absence of large-scale forcing for synoptic lift/neutral- to-weak height rises, diurnal heating - which may be delayed due to cloud cover early in the day - and small scale shortwave impulses will play a key role in renewed convective development. This of course adds some degree of uncertainty into the forecast. Assuming this occurs as is generally depicted by a consensus of CAM guidance, a few strong to locally damaging wind gusts will be possible mainly over Northwest PA within corridor of high PW and 30-40kt mid-level flow. Expect any storms to weaken after dark given loss of instability, with decreasing coverage into the overnight hours. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
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There is increasing confidence in a dry Friday, as all models now push dying cold front southeast of the region by 12Z Sat. Main effect of fropa will be to lower humidity, as GEFS 8h temps remain above normal behind front, likely supporting max temps from the low 80s across the nw mtns, to around 90F in the Susq Valley. Model soundings suggest Friday could begin mcldy over the Alleghenies, but any post-frontal stratocu should mix out to msunny skies everywhere by aftn. Sfc high will build over the region Friday night, resulting in a fair and mild night. Will have to watch for the possibility of patchy valley fog over the northern mtns late.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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Center of subtropical ridge over the southeast conus is progged by all models to migrate northeast to the Mid Atlantic by this weekend. Lg scale subsidence and warm temps aloft assoc with this feature should translate to hot and humid conds with little chance of rain across most of Central Pa. However, a shortwave tracking across southern Ontario could trigger sct late day shra/tsra on Sunday across northwest Pa. 00Z NAEFS and ECENS both strongly favor a continuation of well abv normal temps into next week with mean 8h temps still btwn 18-20C. Weakening upper ridge is progged by mdls to slip southward a bit, placing Pa within a more favorable regime for diurnal convection on northern edge of upper ridge within plume of anomalous PWATS. High humidity and warm nights appear likely into next week, esp across southern Pa, where anomalous PWATs on the order of +1SD indicated in the 00Z GEFS.
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&& .AVIATION /09Z 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...Steinbugl NEAR TERM...Fitzgerald/Steinbugl SHORT TERM...Fitzgerald LONG TERM...Fitzgerald AVIATION...Steinbugl

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