Area Forecast Discussion
Issued by NWS State College, PA

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914 FXUS61 KCTP 240002 AFDCTP Area Forecast Discussion National Weather Service State College PA 802 PM EDT MON MAY 23 2016 .SYNOPSIS... The slow moving storm system that brought rainy cool weather all weekend will slowly edge away from the region today and Tuesday. A noticeably warmer and more summer-like pattern is forecast from mid week into the holiday weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Showers and isolated thunderstorms slowly diminishing across southern half of central PA this evening. Cyclonic circulation and low heights around offshore upper low circulation created rare NE to SW storm tracks this evening...with one prolific hail producer in Lancaster/York Counties. Red Lion saw the ground whitened by 4-5 minutes of pea to nickle sized hail. Very weak environmental winds but southwest propogating cold pools produced local 30+ mph wind gusts with isolated tree damage...and an already delapidated structure in Lancaster County was further damaged. HRRR continues the current trend of the regional radar mosaic in dissipating showers completely by late evening. Most areas will clear out overnight. In areas of rain this afternoon..increased chance of patchy valley fog. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Tuesday looks to be a generally good day. Low probability of precipitation. Mostly sunny day. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Extended guidance continues the idea the development of an eastern ridge/western trough pattern, bringing the arrival of the first extended period of summer-like temperatures and humidity. By Wednesday... central PA will be under rising heights as the low lifts out and the ridge bulges east. At the same time a weakening back door cold front will be sliding out of Canada into the rising heights aloft. The models use this to develop scattered showers and thunderstorms Wed afternoon and evening. Precip confidence is never terribly high with surface fronts moving into ridges aloft. By Thursday we will be embedded in a broad wsw flow aloft. Slightly above normal PWATS support the idea that humidity will become noticeable over most of the area for the first time this warm season. It also means we will be susceptible to mainly afternoon convection pretty much on a daily basis into the weekend. The limiting factor will be the eventual sharpness of the upper ridge and how warm we manage to get aloft. The GFS is very aggressive poking the Bermuda ridge strongly up over the eastern U.S. Saturday while the ECMWF is a little flatter. The NAEFS is more in line with the GFS which hints that Saturday could be the day with smallest convective chances. I don`t have anything more than chance pops in the extended given the muddy nature of the ridge and low confidence that it will be able to shield us from upstream convection that will be embedded in the flow. The highest confidence part of the forecast is for temperatures to be above normal through the end of the month. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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Regional radar mosaic at 00Z shows the last of the diurnally-driven showers falling apart over southern Pa. For much of central Pa, confidence in vfr conds overnight is high. However, fog is a concern across portions of southern Pa, esp where rain fell earlier today. The dwpt depression at KMDT is only 6 degrees at 23Z, and with clearing skies developing toward sunset it`s an ideal setup for fog. Current hrrr and lamp guidance not indicating any vis restrictions there this evening and only mvfr restrictions late tonight, but felt compelled to paint a more pessimistic picture in the TAF. Current dwpt depressions and SREF probs suggest KLNS may also experience some fog late tonight. Elsewhere, the prospects of sig vis reductions appear low overnight. Ridge of high pressure will build in from the west on Tuesday, bringing a near certainty of widespread VFR conds. OUTLOOK... Wed...No sig wx expected. Thu-Sat...Isold pm tsra impacts possible.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...Grumm/DeVoir SHORT TERM...Grumm LONG TERM...RXR AVIATION...Fitzgerald

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