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Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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973 FXUS61 KCTP 032345 AFDCTP Area Forecast Discussion National Weather Service State College PA 745 PM EDT Wed Jul 3 2024 .SYNOPSIS... Warm and humid conditions will prevail through week`s and into the start of the coming weekend. A weakening cold front will push in from the Great Lakes tonight, then stall out over the area late this week. Low pressure tracking north of Pennsylvania will drag a cold front through the state Saturday. Drier and more comfortable conditions are expected for Sunday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... The focus tonight will be on a an approaching, slow-moving cold front, which lies from near Detroit into Northern Indiana at 22Z. Diurnal heating ahead of the front has resulted in a band of convection along the attendant low level jet/plume of highest pwats from the Ohio Valley into Northwest PA. Expect the prefrontal convection to make slow eastward progress overnight and diminish in coverage/intensity with loss of heating. Latest convection-allowing guidance supports a good chance of showers and isold tsra across the NW Mtns tonight, but little chance of any rain reaching the Lower Susq Valley. By dawn, the best chance of showers will likely be in the vicinity of the surface cold front, which is progged to be entering the N Mtns by that time. Surging pwats ahead of the cold front, combined with modest instability, could support some locally heavy downpours later this evening over the extreme northwest part of the forecast area (Warren Co). Otherwise, rainfall amounts should generally remain light, with most locations southeast of the Allegheny Plateau remaining dry. Mostly cloudy skies over the northwest counties and increasing clouds elsewhere, combined with surging humidity, will result in a much warmer night than we`ve seen recently, with low temperatures in the mid 60s to lower 70s. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/... The front will slowly sag across the area on Thursday, with a mostly cloudy day in store for the Fourth of July and even muggier conditions as dewpoints reach the lower 70s in some spots. Morning showers and storms associated with the decaying cold front will gradually move southeast through the day and should remain scattered in coverage. The front will be located over southern PA by Thursday afternoon, which is where most of the shower activity should be concentrated for any 4th of July and/or fireworks festivities. Highs on Thursday afternoon will generally be in the 80s with a few spots potentially reaching 90 degrees in the southeast before convection arrives. Severe and excessive rainfall risks remain low on Thursday, with SPC MRGL clipping portions of my southern tier counties THursday afternoon/eve. Rain is greatly needed in areas that have the highest POPs Thursday afternoon. Any stronger storms could produce gusty winds and potentially a downburst, but this seems contingent on there being some breaks in the clouds to fuel potential instability. As mentioned previously, bulk shear near the front will be sufficient for organization, but CAPE may be lacking owing to persistent cloud cover. Regardless, the chance of showers and storms should be monitored for anyone who plans to take part in outdoor festivities to celebrate Independence Day. The front is progged to stall out in the vicinity of Southern PA Thursday night, then return north as a warm front Friday ahead of low pressure lifting across the Grt Lks. Falling heights and surging pwats ahead of an upstream shortwave and associated surface low lifting across the Grt Lks should bring a round of showers/tsra in the Friday PM to Saturday timeframe. Current guidance suggests the shortwave and bulk of the large scale forcing will pass north of PA, leading to unimpressive mean qpf in the ensemble plumes of 0.25 to 0.50 inches Fri PM to Saturday. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Deterministic guidance continues to outline fair and seasonable conditions on Sunday and into early Monday with surface ridging and drier air working in behind the frontal passage. There is a bit of uncertainty into the later hours on Monday as ECMWF guidance outlines drier conditions prevailing across all of central PA, with GFS outlining some showers and thunderstorms Monday late afternoon/evening across mainly southern Pennsylvania where moisture and lift will be slightly more favorable. Given some uncertainty, have mainly kept PoPs confined along the Turnpike and the higher elevations of Schuylkill County for this forecast cycle, slightly cutting back from NBM PoPs in this timeframe. Both ENS and GEFS plumes begin to outline greater chances for precipitation into Tuesday, as a low pressure north of the area continues to push eastwards and drag a cold front across the region. Some instability will bring some potential for storms especially in the afternoon/evening hours, but cannot rule them out throughout the morning hours during this forecast cycle. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... A few showers have developed across the northern tier and will continue to push eastward over the next few hours. More showers and thunderstorms ahead of an approaching cold front are expected to move into the region tonight, with the bulk of the overnight activity expected to remain across the northern half of the area. Ceilings will gradually lower at BFD as these showers and storms move in, and a period of MVFR ceilings is likely afer 06Z with IFR ceilings expected after 09Z. There is fairly high confidence that the low clouds extend down to JST with the HREF showing a 60-70% chance of MVFR ceilings there. Elsewhere, VFR conditions are anticipated. As the front progresses through the area, thunderstorms will become more focused across the south. While all sites will likely see thunderstorms at some point during the TAF period, the exact timing of thunder will have to be adjusted in the forecast once we have a better idea of the exact placement of storms. Brief visibility restrictions and gusty winds will be possible in any of the stronger thunderstorms. Outlook... Fri...Sct TSRA w/ possible impacts; Mainly PM w/ highest coverage across the west. Sat...Sct to Nmrs TSRA areawide, highest chances SE in PM. Sun...AM fog possible; otherwise, no sig wx. Mon...SHRA possible SE late PM; otherwise, no sig wx. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/Fitzgerald NEAR TERM...Fitzgerald SHORT TERM...DeVoir/Fitzgerald/Banghoff LONG TERM...Fitzgerald/NPB AVIATION...Bauco