Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 140331 AFDCTP Area Forecast Discussion National Weather Service State College PA 1031 PM EST Fri Jan 13 2017 .SYNOPSIS... An upper air disturbance will link up with a weak trough of surface low pressure nosing in from the Ohio River Valley late tonight and Saturday to bring periods of light snow to central portions of Pennsylvania and mixed precipitation or freezing rain across the south. Another area of high pressure will build east into the region for Sunday with some sunshine, seasonably cold temperatures and a light northwesterly breeze. Milder conditions will work back into the area for the middle of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Regional radar mosaic at 01Z shows a band of light mixed precip over the Ohio Valley into W Virginia associated with fgen forcing in entrance region of jet streak over the eastern Grt Lks/NY state. Latest model guidance suggests the northern edge of this precip shield may just barely sneak across the Mason Dixon Line after midnight. Model soundings support the mixed ptype forecast, with light snow/sleet/fzra equally possible as precip works into southern Somerset/Bedford/Fulton counties late tonight. For the rest of central Pa, a dry night is in store under thickening cloud cover. Min temps expected to range from the mid teens over the northern tier, to the upper 20s across the Lower Susq Valley. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Light snow and mixed precipitation will slowly advance northward into the southern half of Pa Saturday, as weak wave of low pressure approaches from the Ohio Valley. Latest guidance indicates a changeover to sleet and freezing rain across my southern tier where advisories are now in effect. Farther north, little if any snowfall is expected north of I80...thanks to cold dry high pressure. Light mixed precip will taper off by Saturday evening across the south. Blend of latest model guidance indicates any snow accums across central and southern Pa will be very light, ranging from zero to a half inch. Likewise, any icing across the southern counties will be very light as well, but enough to create travel concerns. Highs will be within a few degrees of freezing across the south, ranging to the upper 20s north. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Light mixed precip (or very light snow) may linger for a few hours into the evening hours Saturday across southern portions of our CWA. Little if any additional snow or ice accum is expected though as precip will be light. Partial clearing or better will occur after midnight Sat with just a few flurries possible across the northern and western mtns of the state. High pressure will build into the area from the Upper Great Lakes on Sunday, supplying us with fair, chilly weather and relatively light nwrly wind. High temps will rebound by some 5-8 deg F on Sunday with respect to Saturday`s highs. At the same time, stubborn trough/upper low over the west coast weakens and lifts across the southern plains into the great lakes region as pattern. Ridge over the area tries to hold firm as a warm front lifts through Ohio River Valley early in the upcoming week. This frontal boundary will be preceded and accompanied by a light, wintry mix of precip during the morning hours Monday. A good portion of next week is shaping up to be mild and showery, as bulk of med range guidance shows a ridge slowly retreating off the East Coast as remnants of that west coast low get picked up by the northern stream and track across PA midweek. For Tue into Tue night, deep southerly flow ahead of that trough will bring a plume of anomalous PWATS over the region which supports the idea of showery (rain) and mild weather. As has been the case frequently lately, the GFS brings the trough through faster than the ECMWF. Winds turn westerly behind the system as flow turns more zonal, but with no cold air in sight, temps will remain mild and above freezing. Ridge re-establishes itself over the eastern U.S. for late week, as mild SW flow persists over the midwest. We`ll be on the eastern side of this, so subtle shortwaves sliding into the Midwest will bring varying amounts of cloudiness to the west (less in the east) with low end chances for light showers. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
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VFR conditions will prevail tonight as mid-high clouds continue to increase across the forecast area. A wintry mix will spread northeast, reaching the southern Laurels around or shortly after sunrise. The area of mixed snow/sleet/freezing rain will continue northward Saturday morning, reaching JST-AOO by mid morning, and to about I-80 by mid day. Latest guidance suggests light snow along the very leading edge of the precipitation with a changeover to the wintry mix over about the southern half of the state. Where it snows, visibilities will quickly become IFR with the area of sleet and freezing rain favoring low VFR or MVFR conditions. These will develop during the morning and continue throughout the day. The northern third of the local flying area will remain VFR throughout as the precipitation slides just to the south. Reduced conditions over southern areas will continue into Saturday night with improving conditions returning for Sunday. Outlook... Mon-Tue...Sub-VFR likely with chc of freezing rain/rain. Wed...MVFR and snow showers west and north, VFR elsewhere.
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&& .CTP WATCHES/WARNINGS/ADVISORIES...
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Winter Weather Advisory until midnight EST Saturday night for PAZ033>035. Winter Weather Advisory from 7 AM Saturday to midnight EST Saturday night for PAZ024-025-036-064-065.
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&& $$ SYNOPSIS...DeVoir NEAR TERM...Fitzgerald SHORT TERM...DeVoir/Fitzgerald LONG TERM...RXR AVIATION...La Corte

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