Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 212346 AFDCTP Area Forecast Discussion National Weather Service State College PA 746 PM EDT Mon May 21 2018 .SYNOPSIS... An area of high pressure will slide across upstate New York today. The frontal boundary that pushed southeast across the region Sunday will lift back to the north as a warm front later today into Tuesday. A cold front will sag southeast across the Commonwealth Tuesday afternoon and evening. High pressure will then bring a period of mainly dry weather with pleasant temperatures for Wednesday through Friday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... High pressure and associated low PWAT air mass tracking across southern New England is providing most of central Pa with a sunny evening. Somewhat higher dewpoints have resulted in scattered cumulus across the south central mountains and Laurels. Can`t rule out an isolated evening shower or thunderstorm over Somerset County, where SPC mesoanalysis is showing capes to near 1000 j/kg. An approaching warm front will bring an increasing chance of rain and possible embedded thunderstorms back into central PA late tonight. Latest model guidance supports near 100 pct POPs across the northwest counties, as nose of low level jet pushes through this part of the state roughly between 04Z-09Z. Will maintain lower POPs of around 50 pct across the southeast portion of the forecast area. Models continue to indicate some elevated instability tonight across the Allegheny Plateau, where thunderstorms could accompany the rain. Further east, see little chance of thunder due to stable air mass entrenched across the eastern half of the state. Increasing cloud cover ahead of approaching warm front will help to hold temperatures up tonight. Expect min temps to range mostly between 55 and 60. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Low level stability forecasts suggest the warm front could be slow moving north on Tuesday keeping relatively stable air in place over eastern areas at least into the afternoon hours. SPC shows us in a marginal risk but that seems like it will be dependent on the amount sun we can manage. I would think my western zones would be most at risk for a severe storm given the stability and shear being displayed at this point in time. Humidity will become noticeable as dewpoints push back into the 60s. Highs Tuesday will be a couple of deg either side of normal. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Unsettled weather continues Tue night with muggy airmass over the area. This will lead to a warm day Wed. Drier air will begin to filter into the area with pops decreasing through the day. Look for high pressure and dry weather Thursday and Friday with seasonable morning lows and warm afternoons. Saturday is trending drier and will probably be the warmest day of the holiday weekend with most locations in the 80s. A more unsettled, humid and a little cooler weather is likely by the end of the weekend and on Memorial Day. While there will be pops in the forecast, still uncertain exactly how wet things will turn out. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... VFR conditions exist across all of Central Pennsylvania this evening, although high clouds from approaching convection already overspreading from the west. A warm front will begin to push north overnight bringing widespread showers with embedded thunderstorms, along with deteriorating flying conditions. Look for MVFR/IFR to develop overnight. Tuesday will start with widespread rain/showers and even some embedded thunderstorms, along with associated MVFR/IFR conditions. Some slow improvement possible later Tuesday, with a cold front crossing the region. However, the cold front may trigger a gusty thunderstorm or two. Outlook... Wed...AM MVFR/IFR cigs wrn 1/3. Thu-Fri...VFR/No sig wx expected. Sat...Mainly VFR with scattered showers/thunderstorms. && .CLIMATE... Some perspective on the recent wet pattern... Total rainfall during the past 1 & 2 week periods ending on 5/19 ranked as the WETTEST on record at Harrisburg. Also through 5/19, the 5.28 inches of total rainfall ranks as the 3rd wettest month-to-date period. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...Fitzgerald/La Corte SHORT TERM...La Corte LONG TERM...Ross AVIATION...Jung/La Corte CLIMATE...Steinbugl

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