Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 161035 AFDCTP Area Forecast Discussion National Weather Service State College PA 535 AM EST Sat Dec 16 2017 .SYNOPSIS... Cold northwest flow and lake effect snow showers in the lee of Lake Erie are expected today. High pressure and a brief moderating trend in the temperature are expected by Sunday. A series of cold fronts will move across the area late Sunday into Wednesday. Windy and colder temperatures will follow. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Upper trof moving off of the eastern seaboard this morning with channeled northwest flow organizing lake effect snow bands over the eastern lakes and depositing over my northwest mountains. CAMs indicate incoming banding will extend into the central and north central mountains this morning with light coatings expected there. Going advisories in good shape with several more inches of accumulation expected through this afternoon. Lake effect snow showers will diminish by late this afternoon as heights continue to rise and inversion heights lower. It will still be colder than normal with highs ranging from the upper 20s northwest to around 40 over the south.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... HIgh pressure centered over eastern Ontario and southern Quebec and over the southeastern coastal states tonight will bring fair and cold conditions. Upper ridging will be tempered on Sunday by an embedded disturbance in the return moisture flow west of the sfc ridge axis, which may bring scattered rain and snow showers to the southern third of central PA Sunday afternoon. Amounts will be barely measurable, and with marginal sfc temperatures am not expecting any accumulations...just melting at this time. Highs will range from the mid 30s north to the lower 40s south on Sunday. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... This coming week will see the long-wave upper level trough that has been dominating out weather shift east as a deep trough digs over the Western U.S. Lake enhanced snow showers should be ending by Saturday night with the surface high pressure ridge moving off the coast and the winds becoming move west to southwesterly. The western trough kicks a strong shortwave out across the Plains Sunday into Monday. The associated low center will move northeast across the Great Lakes staying to our North and west. This system will bring in warmer air in southwest flow ahead of it. However, we may be cold air dammed near the surface so the +1 to -2C air at 850 hPa may not translate to a warm boundary layer. The warm advection should bring snow and snow to rain in the south but QPF amounts are light. Will have to watch for potential for some ice also Sunday night. We look to move into a fast moving pattern of weak shortwaves and chances for precipitation (mainly over the northern mountains) through the week. As a northern stream wave zips by to our north by Monday night, it should drag cold air back into the region Tuesday into Wednesday. The northwest flow triggers snow in relatively high POPS in NW PA due to LES. This cold surge should be relatively fleeting and high pressure and a potential surge of relatively warmer air follows Thursday. The warm advection and approaching cold front will likely produce increased potential for snow in NW Thursday into Friday. Farther south any precipitation would likely be mixed or rain. A strong frontal boundary will likely push another surge of cold air into the region Friday into Saturday as the eastern long wave trough tries to re-establish itself. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... The snow bands have lessened thought stronger bands continue through NW. Most of the snow is producing VFR to MVFR restrictions, with some heavier snow showers are producing IFR restrictions at BFD. Arctic fropa overnight will shift winds to the northwest, producing a more favorable over-lake trajectory. This will invigorate snow showers over the western and northern mountains. Result will be highly variable visibility conditions in the north and west as snow showers drift in and out. Outlook... Sat...Scattered snow showers and local restrictions NW/Laurels. Sun-Mon...Mainly VFR. Tue-Wed...mainly VFR, but possible restrictions in the western and northern mountains in snow showers. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 4 PM EST this afternoon for PAZ004-005. && $$ SYNOPSIS...DeVoir NEAR TERM...DeVoir SHORT TERM...DeVoir LONG TERM...Watson AVIATION...Jung/Ceru

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