Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 221209 AFDCTP Area Forecast Discussion National Weather Service State College PA 809 AM EDT Tue May 22 2018 .SYNOPSIS... Low pressure will track across the eastern Great Lakes today and push a warm front across Pennsylvania. A trailing cold front will then sag southeast across the Commonwealth tonight. High pressure will build southeast into the region for the second half of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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The RAP low level LI field suggests the warm front is over eastern PA, but the surface meso-anal doesn`t support this with a low level cool wedge and SE winds. The weak surface low is over southern WI with the wavy front eastward over Lake Erie. This will continue to track down the ST. Lawrence which will lead to the cool wedge mixing out and leaving the local area in the warm-humid and unstable airmass. Radar shows widespread rain showers and these are stacked up all the way back to southern OH so a wet day is in store, with a few thunderstorms thrown in for good measure. Model CAPEs` suggest that western areas will break out today and become the most unstable with CAPE`s in excess of 1500J possible. HREF radar forecast shows the steady rain moving through this morning with more in the way of scattered showers/storms in the afternoon, but none of the CAMs suggest strong convection at this time. From earlier... Still focused on MRGL severe potential in the warm sector over mainly western and central portions of the state. Overcast skies should give way to breaks of sunshine west of the warm front during the afternoon, leading to moderate instability. Large scale forcing ahead of approaching shortwave over the Grt Lks and favorable jet dynamics beneath right entrance region will enhance the convective potential. 0-6km shear in the 40-45kt range will likely support organized bands of convection and possible supercells across the western counties. Cloud cover through at least the first half of the day will hold temperatures down, although humidity will become noticeable as dewpoints push back into the 60s. Highs will range from the low to mid 70s over much of the forecast area, with readings possibly stuck in the 60s east of the Susquehanna River.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
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Trailing cold front sags across the region this evening, starting over the NW Mountains by 00z this evening and clearing my southeastern counties after 06z. A few post-frontal showers may still linger into the early AM on Wednesday, but much improved conditions are expected later Wednesday morning and afternoon as much drier air aloft arrives and PWs fall to between 0.55" and 0.65" in the afternoon. Highs will range through the 70s with a comfortable northwest breeze in the afternoon.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Look for high pressure and dry weather Wednesday night through 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 /12Z TUESDAY THROUGH SATURDAY/...
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Scattered to numerous showers with embedded thunderstorms have spread across much of the airspace since midnight. Flight categories have been holding VFR for the most part, but anticipate lowering trend to MVFR through the predawn hours into mid Tuesday morning. Latest guidance favors a consolidation of rain areas over the eastern airspace by mid-late morning. Current thinking is that a resurgence of isolated to scattered showers and thunderstorms will develop in the OH vicinity during the afternoon and move east southeast in advance of a cold front pushing southeast from the lower Lakes. A few of these storms may be strong to severe with localized bouts of hail/wind before weakening during the evening. The great risk area at this time appears to be over the southwest 1/3 of the airspace. It appears the AM rain/clouds will maintain stability and limit thunderstorm potential over the eastern airfields. Therefore, kept mention of TS out of KIPT/KMDT/KLNS TAFs. Outlook... Wed...AM MVFR/IFR cigs wrn 1/3. Thu-Fri...VFR/No sig wx expected. Sat...Mainly VFR with scattered showers/thunderstorms.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/La Corte NEAR TERM...DeVoir SHORT TERM...DeVoir/Fitzgerald/La Corte LONG TERM...Ross AVIATION...Steinbugl

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