Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 182019 AFDCTP Area Forecast Discussion National Weather Service State College PA 419 PM EDT Sun Mar 18 2018 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Clear skies dominate the weather this afternoon over central PA. West winds have picked up a bit in deep layer mixing, but overall speeds in that layer are light resulting in surface speeds around 10 mph with occasional gusts to 15-20 mph. It is also quite dry out there today with RH values between 20-30%. Though RTMA not doing too bad overall, near term model forecasts (esp HRRR) have really been struggling with dewpoint forecast all day long requiring forecaster-based adjustments in the grids. Highs do look like they will top out near both this morning`s MaxT forecast numbers and seasonal averages - peaking in the 40s to lower 50s. Clear skies will continue in most places overnight with lows dropping back into the teens and 20s, with dewpoints slowly rising through the teens 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/...
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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.
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&& .AVIATION /20Z SUNDAY THROUGH FRIDAY/... VFR conditions will persist nearly everywhere into Mon night. However, there is a low chance of MVFR stratocu dropping from NY state into northern PA late this evening associated with the passage of a weak cold front. But the airmass remains quite dry over our area which will erode most of these clouds as they drop southward overnight. WNW winds around 10 mph become light tonight. Low level flow gradually turns around to the SE ahead of a low pressure system progged to track to our south Mon night into Tue. Biggest impacts of this system will be south of the PA Turnpike and southward into the Mid-Atlantic region Mon Night into Tues. Outlook... Mon...No sig wx expected. Tue...Snow/restrictions likely southern Pa...mainly early AM. Wed...AM light snow possible southern tier. Thu...No sig wx expected. Sct cig restrictions poss NW/Laurels. 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...RXR SHORT TERM...RXR LONG TERM...Steinbugl AVIATION...RXR CLIMATE...Steinbugl is the U.S. government's official web portal to all federal, state and local government web resources and services.