Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 100805 AFDCTP Area Forecast Discussion National Weather Service State College PA 305 AM EST Sun Dec 10 2017 .SYNOPSIS... Low pressure will move off the mid Atlantic coast tonight. A deep upper level trough will remain over the eastern conus into Thursday, before a westerly flow of milder air works into the area by next weekend. Low pressure moving just north of the area late Sunday will bring some snow to the north and west Sunday into Sunday night. Another low moving just north of the area late Monday night will bring some snow to the area late Monday into Tuesday, mainly across the north and west. && .NEAR TERM /UNTIL 7 AM THIS MORNING/...
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Regional radar loop at 0730Z showing light, orographically enhanced lake effect snow overspreading western Pa. HREFV2 qpf suggest most of the Allegheny Plateau will see a fresh dusting between 06Z-12Z. However, the snowbelt of northwest Warren County is likely to see additional accums of around an inch between 06Z-12Z. Expect partial clearing east of the Alleghenies during the pre- dawn hours, as large scale subsidence briefly overspreads the region behind departing mid level shortwave. Lake effect stratocu will keep skies overcast across the western counties.
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&& .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM TODAY/...
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Light, orographically enhanced lake effect snow should taper off over the Alleghenies by this afternoon, as boundary layer flow backs to the southwest. HREFV2 qpf is supporting an additional inch of accumulation between 12Z-18Z across the snowbelt of northwest Warren County, while no more than an additional dusting is expected over the rest of the Allegheny Plateau. Downsloping subsidence should result in partly sunny, dry weather east of the mountains later today, while stratocu trapped beneath subsidence inversion lingers over the western portion of the forecast area. Mixing down model 850mb temps of -10C to -12C translates to below normal max temps today, ranging from the upper 20s over the Alleghenies, to the mid and upper 30s in the Susq Valley. A gusty west wind will add an additional bite to the air. Bufkit soundings support frequent gusts to around 20kts.
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&& .LONG TERM /TONIGHT THROUGH SATURDAY/...
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A weak low moving north of the area will bring a northwest flow of air to the area late Sunday into early Monday. This will result in some snow showers. A stronger low moving across upstate New York on Tuesday will bring some snow to the area late Monday night into Tue. THis will be followed by a cold northwest flow across the Great Lakes. This will result into some snow showers off the lakes. The west coast ridge weakens some toward next weekend, which will result in a westerly flow of milder air working into the area. Minor changes to the package. Went with dry conditions next weekend.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/... The snow bands have moved eastward however, Periods of IFR will continue at LNS with reduced vsbys until around 06Z. The focus will continue to shift to the NW as the westerly upslope flow will continue to bring restrictions and widespread snow showers to the northern/western mountains along with brisk NW flow and the potential for scattered heavier squalls that will linger into the first half of Sunday. Scattered snow showers will bring intermittent MVFR incursions into the central mountains, while downslope flow will keep the SE VFR. Outlook... Sun...AM snow showers/reductions likely Allegheny Plateau, becoming confined to the NW mtns in the afternoon. Scattered squalls also poss. Mon...Cig reductions likely western portions. PM light snow developing, mainly northwest Pa. Mon night and Tuesday...Periods of light snow. Widespread MVFR likely, with periods of IFR and brief LIFR cigs and vsbys. Wed...Reductions poss west in sct snow showers. Otherwise VFR. Thu...Still a chance of a few snow showers. && .CTP WATCHES/WARNINGS/ADVISORIES...
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Winter Weather Advisory until 3 PM EST this afternoon for PAZ004.
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&& $$ SYNOPSIS...Dangelo NEAR TERM...Fitzgerald SHORT TERM...DeVoir/Fitzgerald LONG TERM...Martin AVIATION...DeVoir/Ceru

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