Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 190247 AFDCTP Area Forecast Discussion National Weather Service State College PA 1047 PM EDT Sun Mar 18 2018 .SYNOPSIS... Fair and dry conditions will continue tonight into Monday. The start of Spring will marked by a rain/snow mix with light to moderate accumulations possible across south central Pennsylvania Tuesday into Wednesday. Cooler than average temperatures will dominate the pattern through the end of the week, with the next opportunity for precipitation coming this weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Valley winds have really dropped off the last few hours. Clear skies will continue to prevail overnight. Dewpoints in the teens will allow temperatures to cool off nicely and lows will fall into the teens and 20s, with dewpoints slowly rising to around 20F in all but the NE. Some stratocu should develop over upstate NY and try to slide into the northern mountains as a weak cold front slips through, but dryness of airmass should erode most of these clouds as they drop southward overnight. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... Monday will remain fair and dry, but with a gradual increase in clouds late in the day from S to N. Low level flow starts off light from the NW, but gradually turns around to the SE ahead of a low pressure system progged to track to our south Mon night into Tue. Highs will range from the mid 30s north to around 50 south. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... A pair of low pressure systems tracking to the south of PA across the southern Mid Atlantic region Mon. Night-Tue will eventually consolidate into a deepening cyclone off the New England coast Wed-Thu. It looks increasingly likely that Spring 2018 will start off on a wintry note with accumulating snow a good bet across far south central PA on Tuesday. Model guidance was in pretty good agreement QPF-wise Mon. Night into early Tuesday, but made a northward shift later Tue. into early Wed. The best period for accumulation will be early Tuesday morning and again during the late evening/overnight hours into early Wed. morning. Several inches are possible south of the PA Turnpike, particularly in the higher elevations but late-season factors will come into play. Timing and intensity will be key, with accumulation -especially on roads- very difficult this time of year from mid morning to mid afternoon due to the strong March sun. So just how disruptive the snow is on travel/AM Tue. commute is still in TBD with road conditions likely varying from wet to slushy or snow covered. We added the Tue. Night period to the storm total snow which now stretches from 00Z Tue to 12Z Wed. The late-season factors including marginal temperatures and elevation/precipitation-rate dependence continue to make this a challenging forecast. Pattern favors mainly dry wx and below average temperatures through the late week period, with a cold wind on the backside of the coastal storm. Models show the next opportunity for precip arriving this weekend as low pressure streaks east from the Plains. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Model data continues to support a high confidence forecast of VFR conditions and light wind over most of central Pa through Monday. However, there is a chance of MVFR stratocu dropping from NY state into northern PA early Monday morning associated with the passage of a weak cold front. Any stratocu that does affect northern Pa should mix out by late morning, with widespread VFR/light winds Monday afternoon. Outlook... Tue...Snow/restrictions likely southern Pa. Wed...AM light snow possible southern tier. Thu-Fri...No sig wx expected. && .CLIMATE... The Spring (Vernal) Equinox will be at 12:15 PM on Tuesday, March 20. Sunrise in State College, PA will be 7:14 AM and sunset at 7:23 PM, for a total daylength of just over 12 hours. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...DeVoir/RXR SHORT TERM...RXR LONG TERM...Steinbugl AVIATION...Fitzgerald CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.