Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 211021 AFDCTP Area Forecast Discussion National Weather Service State College PA 621 AM EDT Fri Jul 21 2017 .SYNOPSIS... Pennsylvania will be on the northern periphery of a subtropical ridge passing across the southern states through the weekend. A slow moving cold front will push through the area early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Satellite loop at 09Z showing fairly widespread low clouds and fog across the Alleghenies. Model soundings indicate this low level moisture will mix out to a sct-bkn cu field by late morning. Large scale subsidence and arrival of much lower PWATs should result in a rain free Friday for most if not all of the forecast area. However, will maintain a slight chance of an afternoon thunderstorm near the Mason Dixon Line, which will remain on northern edge of ring of fire. GEFS mean 850 temps still around 18C today, which should translate to max temps from the mid 80s over the northern mountains, to the low 90s in the Susq Valley. The southeast counties fell just short of heat advisory criteria yesterday and expect a similar scenario today with heat indices over that part of the state peaking in the upper 90s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Any isolated diurnally-driven showers/storms along the southern tier should die out around sunset. Otherwise, all model guidance supporting a dry forecast tonight, as weak surface ridge passes over Pa. Concern remains for possible severe weather Saturday PM, as warm front pushes into the region ahead low pressure over the Grt Lks. Extensive cloud cover associated with warm front will likely result in limited CAPE Saturday as the 00Z GEFS shows. However, a powerful low level jet and plume of anomalous PWATs is progged to work through the area Sat night. Convection associated with this feature could potentially evolve into an MCS with potential for overnight severe weather in central Pa. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Favorable scenario for additional severe weather across central Pa Sunday as the region will be within warm sector south of anomalous surface low tracking eastward along the PA/NY border. Moderate CAPES and moderate westerly flow aloft, combined with large scale forcing ahead of approaching upper trough, should support widespread convection by afternoon. Some uncertainty with regards to timing of upper trough passage early next week, but additional showers/storms appear possible. A period of dry and cooler weather appears very likely by midweek, as upper trough axis finally passes east of Pa and surface high builds into the area. && .AVIATION /10Z FRIDAY THROUGH TUESDAY/...
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Lower Susq remains VFR, but fairly widespread low clouds and fog across the western portion of CWA (Allegheny Front) early this morning - with IFR conditions extending from BFD-JST and MVFR working into the central mtn sites of AOO-UNV. Model soundings indicate this low level moisture will mix out to a sct-bkn VFR cu field by mid-late morning - likely lingering the longest at JST. Large scale subsidence expected to result in a rain-free Friday for most, though slight chance for an afternoon thunderstorm will persist across southern mtns in deeper moisture. Quiet night tonight, with most locales remaining VFR, though the usual spiderweb of valley fog will settle into the western and northern mtns. Warm front pushes into the region on Sat followed by an upper trough on Sun, which will keep numerous showers and thunderstorms around over the weekend. .OUTLOOK... Sat...AM valley fog possible. TSRA/SHRA likely with intermittant impacts. Sun...AM valley fog likely. Cig restrictions likely north. TSRA/SHRA likely with intermittant impacts. Sun night...Cig restrictions likely. Scattered TSRA/SHRA. Mon...AM restrictions likely. Scattered TSRA. Tue...Patchy AM fog. Otherwise no sig wx.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Fitzgerald AVIATION...Jung/RXR

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