Area Forecast Discussion
Issued by NWS State College, PA

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673 FXUS61 KCTP 151927 AFDCTP Area Forecast Discussion National Weather Service State College PA 327 PM EDT Tue Jul 15 2025 .SYNOPSIS...
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* Elevated risk of excessive rainfall and flash flooding Wednesday afternoon and evening * Scattered thunderstorms with locally heavy rain forecast through late week * Heat risk builds Wednesday and likely peaks on Thursday with potential for heat indices to exceed 100 degrees
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&& .NEAR TERM /THROUGH TONIGHT/...
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Very isolated and weakly forced airmass/terrain induced convection mainly over the Allegheny "rim" this afternoon should quickly dissipate this evening with the loss of daytime heating. Crumbling cumulus gives way to mainly clear skies tonight with areas of fog/stratus are set to redevelop into early Wednesday morning. It will be muggy with min temps 65-75F or 5 to 10 degrees above climo.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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Fog/low stratus mix out shortly after sunrise giving way to a mix of sun and clouds into the afternoon. Key message for tomorrow centers around an elevated risk of excessive rainfall and potential for flash flooding. Return flow pattern continues to set the stage for rounds of enhanced thunderstorms capable of producing very heavy rainfall on Wednesday afternoon and evening. Given impressive thermodynamics (MUCAPE >2000 J/kg), exceptional to near daily record moisture availability (PW 1.5-2.2") and strong llvl convergence signal, localized rainfall rates of 2"/hr are probable and could quickly produce point totals of 2-4" in some areas during the afternoon and evening. This will likely result in instances of flash flooding particularly in areas recently inundated by heavy rain over the past 24 to 48hrs. A watch will likely be needed in the next 1-2 forecast cycles with growing confidence based on recent trends in the hires/CAM guidance. The heavy rain threat should taper off into Wednesday night. While vertical shear will remain quite limited, SPC did expand the MRGL risk over central PA to account for potential isolated strong water-loaded wind gusts that could occur in the most intense storm cores. Building heat and increasing dewpoints are expected through midweek with a peak in Heatrisk on Thursday afternoon. A heat advisory may be needed for portions of south central and southeast PA including the mid and lower Susquehanna Valley. Additional PM thunderstorms with the potential for heavy rainfall are likely on Thursday as a cold front pushes to the southeast from the Lower Great Lakes. Minimum QPF signal over the southeast half of the CWA may be related to capping and warm temps aloft that would limit convective initiation/coverage.
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/...
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Signal in the latest suite of model guidance suggests that we could be in for a bit of a drier and less humid stretch of wx heading through the end of the week/start to the weekend. Sfc cold front stalls just south of the MD line Saturday then returns back to the north as a warm front by Sunday. So on balance, Friday and Saturday could be dry in most places for the majority of the time. Unsettled conditions are likely into early next week with scattered thunderstorms. Typical max/min temps near the historical avg for mid to late July with the largest departures from climo normals vs. nighttime lows.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/... For the 18Z TAF group, added VCSH for most of the area, as clearing skies have quickly resulted in TCU just to the south of the office here. Also showers near JST on the radar since late morning. After Midnight, expect some fog overnight, even without the rain. This based on guidance and that winds will be light and dewpoints still quite high. For Wednesday, a weak upper level trough in combination of high dewpoints and heating will result in the increasing chance of shower and storms across the area after late morning. The activity may linger into at least late Thursday, until a weak cold front drops south and east of the area. Outlook... Thu...Sct/Nmrs SHRA/TSRA. Fri-Sat...Mainly dry. Sun...Showers and storms likely. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Jurewicz/Steinbugl AVIATION...Martin