Area Forecast Discussion
Issued by NWS State College, PA

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872 FXUS61 KCTP 080818 AFDCTP Area Forecast Discussion National Weather Service State College PA 418 AM EDT Tue Jul 8 2025 .SYNOPSIS...
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* Flash flooding and damaging thunderstorm wind risk expected this afternoon and evening across the southeastern portion of central PA * Similar pattern setup for Wednesday with renewed damaging wind and flash flooding risks focused over southeast PA * Best odds for a dry day now appear to peak on Friday; otherwise continued seasonably warm and humid with scattered afternoon and evening thunderstorms through the weekend
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&& .NEAR TERM /THROUGH TONIGHT/...
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Another warm and muggy morning in CPA with areas of fog and low clouds primarily across the western and northern Alleghenies. Shower activity has faded out for the most part overnight with only 1 small area of precip left in the northern tier near KN38. Not as hot today as yesterday across the northwest 3/4 of the forecast area with 24hr MaxT changes on the order of 5-10F to the northwest of I-81. That said, highs will still be near/above climo in most locations. Dewpoints in the 65-75F range will continue to bring humid conditions with max heat index values approaching 100F advisory threshold in the Lower Susquehanna Valley. Convective temperatures will be breached by 17-18z as readings climb into the mid 80s, allowing scattered thunderstorms to readily develop. CAMs show initial t-storm development over southwest/south central PA before noon. As this convection moves eastward with time and takes on a more linear mode, it will carry an attendant risk for isolated damaging wind gusts given an environment characterized by tall/thin, weakly sheared/capped and water loaded sounding profiles. Speaking of water-loading, pwats eclipsing 2" over southeast PA will support a flash flood threat with slow moving t-storms. We issued a flood watch starting 18Z today for a portion of the Lower Susquehanna Valley in coordination with WFO LWX. In addition to the robust and anomalous pwat values, very efficient warm-rain processes could lead to rain rates >2"/hr at times resulting in potential instances of flash flooding. Ahead of the rain, there also remains some concern for max HX values to reach or exceed the century mark in parts of the LSV. A heat advy may still be needed; but for now we will continue to highlight in the HWO. Hires models show the majority of showers/storms will shift to the east after midnight. Min temps trend a bit cooler night over night with fog likely forming in the valleys through the predawn hours Wednesday.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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Similar overall synoptic setup on Wednesday & Thursday with gradual southward shift to the severe t-storm and FF risk areas coincident with zone of max PW. Conditions will remain humid and with daytime highs in the 80s.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...
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The forecast for Friday and the weekend is more uncertain, with some guidance suggesting a break in the unsettled pattern, and others suggesting active weather continues. An active pattern would favor continue heat/humidity while a quieter pattern could support the intrusion of lower dewpoints and more refreshing conditions.
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&& .AVIATION /07Z TUESDAY THROUGH SATURDAY/...
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A very sluggish, weak cold frontal boundary extended from near KBFD to KPIT early this morning, preceded by a surface trough from the Wyoming Valley south to the Lower Susquehanna Valley. A few small clusters of slow moving showers (with brief heavy rain) were noted along and just ahead of the cold front across the North-central Mountains. Muggy air with sfc dewpoints in the upper 60s to low 70s covered much of the SE 2/rids of the state at 06Z and these conditions will persist ahead of this front across much of Central and SE PA, while slightly cooler air with an 8-10 deg F drop in dewpoint values will occur across the NW part of PA today. Patchy fog is possible at all TAF sites early this morning. However, cloud cover and a light breeze from the west early today will likely negate a significant threat for widespread fog. IFR/LIFR ceilings are favored for several hours at BFD and JST with MVFR likely at IPT, UNV, and AOO. A few additional showers could develop by midday today, but showers and thunderstorms will become more widespread as we head into the afternoon. Brief restrictions are possible everywhere except BFD, with storms starting in the vicinity of a line extending from JST/AOO to UNV to IPT and then moving east- southeastward and affecting MDT and LNS later in the afternoon/early evening. Outlook... Tue PM...Showers fade, fog possible across much of the region into Wednesday morning. Wed...Best chance for storms and restrictions in southern PA. Thu-Sat...Potential for showers and thunderstorms, mainly aftn/eve.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... Flood Watch from 2 PM EDT this afternoon through this evening for PAZ057-059-065-066. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Lambert/Banghoff AVIATION...Lambert