Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 282003 AFDCTP Area Forecast Discussion National Weather Service State College PA 403 PM EDT Fri Apr 28 2017 .SYNOPSIS... A ridge high pressure will slide east over the region today. A warm front will move slowly north, keeping moist and mild air in place into early next week. A strong trough should bring cooler drier weather to the region for the second part of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Satellite shows high clouds streaming into the region out of decaying convection over the midwest. We will remain dry today, but the chance for rain will increase this evening and overnight. Guidance indicates that an MCS will form over the Ohio Valley later today and stream NE into the region overnight. ECMWF/GFS as well as The SREF and GEFS all show the MCS decaying as it enters Central PA, while the 12Z NAM and latest HRRR are more aggressive sliding the convection through the area between about 03-10Z. I used a blend of POPs overnight which is not as wet as the HRRR, but wetter than the other models that break up the showers as they approach. I favored the north with the best POPs. Overnight, lows will range from the mid 50s to mid 60s, or about 15-20 deg above normal. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Guidance agrees in bringing the warm front northward late tonight and Saturday, but differences exist as to how far north it manages to progress. Warm and muggy air will pool along and just to the south of the boundary. Models develop a fair amount of CAPE, they just differ on whether the most unstable air will favor the Maryland border areas or extend up into the Central Mountains. SPC has the region under a marginal risk for severe storms, and with moderate deep layer shear expected, this looks reasonable. Look for the best chance of showers and storms to be from mid day into the afternoon. Highs will vary from around 70 along the NY border to the mid/upper 80s over the SE. If we end up with more sunshine than currently expected, I would not rule out a high temp near 90 in a couple of places. With dewpoints well up into the 60s over at least the southern half of the CWA, it will begin to feel humid. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
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Upper level ridge tries to builds in for Saturday night through Sunday but continued southerly flow/instability and a weak warm front lifting through the Ohio Valley and W PA will lead to continued chances for showers and even a tstorm - mainly in the NW half of the area. Temps remain very warm into Monday. A massive and deepening cyclone lifting into the western Great Lakes Sun night into Monday will push a strong cold front through PA Mon into Mon night, accompanied by a round of potentially potent showers and thunderstorms (likely reaching western half of CWA in the afternoon and eastern half during the evening). Once this front passes by much chillier air will advect into PA on cyclonic flow with unsettled light showery weather persisting mainly for the northern part of the state right into Wednesday. Chance for a more widespread light rain arrives Thu into Fri as a low progged to develop along the southern Appalachians and lift northward. Models showing strength/timing issues so not getting to specific this far out, but looks like unsettled weather pattern continues.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... Expect VFR conditions into the evening with localized MVFR/IFR developing with scattered showers and thunderstorms after about 03Z. Guidance suggests an area of thunderstorms this evening causing the restrictions. A slow moving warm front will act as the catalyst for additional showers and thunderstorms/restricted conditions Saturday. The best chance for showers and thunderstorms will be during the afternoon into the evening. Outlook... Sat-Sun...Sct showers/Tstorms with periods of sub-VFR. Mon...Breezy. Showers/thunderstorms likely with periods of sub- VFR. FROPA. Tue-Wed...Breezy with a chance of showers NW 1/2. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...RXR AVIATION...La Corte

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