@ FXUS61 KCTP 200645 AFDCTP Area Forecast Discussion National Weather Service State College PA 245 AM EDT Wed May 20 2026 .WHAT HAS CHANGED... * Low/marginal severe storm risk area now confined to the southern tier of CPA this afternoon into early evening * Reiterating bearish trend for max temps Friday and Saturday && .KEY MESSAGES... 1) A few storms with isolated severe wind gusts and hail will be possible over the southern tier of CPA this afternoon/evening 2) Major cooldown to close out the week and start Memorial Day weekend with widespread soaking rainfall over 1 inch Friday and Saturday && .DISCUSSION... KEY MESSAGE 1: A few storms with isolated severe wind gusts and hail will be possible over the southern tier of CPA this afternoon/evening Sfc cold front crossing western Lake Erie at 06Z will advance south and east across CPA today before stalling out to the south of the MD line tonight into Thursday. Moist and unstable air ahead of the cold front combined with increasing low level convergence will lead to sct thunderstorm development by the afternoon across the southeast 1/2 to 1/3 of the fcst area. The instability along with sufficient 0-6km shear and steep low level lapse rates should support a few stronger storms with potential for isolated severe wind gusts. SPC rolled over the D2 MRGL risk (level 1 out of 5) to D1 with a slight south/east shift in the outlook area. HREF/REFS also indicate potential for locally heavy rainfall >1" near the MD line as showers and storms likely persist through the evening into the overnight period across the southern tier of CPA. ----------------------------------------------------------------- KEY MESSAGE 2: Major cooldown to close out the week and start Memorial Day weekend with widespread soaking rainfall over 1 inch Friday and Saturday Relief from the early season heat wave arrives in earnest on Thursday with max temps 20-30 degrees lower vs. Wednesday across the LSV. Strong high pressure slides from the Lower Great Lakes to off the New England coast to close out the week. Model data shows the high channeling southward down the east-side of the Appalachians, setting up a cold air damming (CAD) event heading into Memorial Day weekend. Increasing CAD signal strength enhanced by moderately strong east/southeast low level flow and soaking rainfall has prompted a considerable bearish/lower adjustment to max temps Friday and Saturday. In fact, highs on Saturday are near daily record lows at several locations (mini/max). Guidance may be too optimistic in rebounding temps Sunday into Monday, but opted to keep baseline NBM for now. That said, the trend will be to moderate warmer with steadier rain giving way to more showery conditions for the unofficial start of summer. NBM/WPC QPF continues to show widespread 48hr rainfall totals in the 1-2 inch range Friday-Saturday. The cool/stable air will cap rates with longer duration helping to mitigate flooding risk in most areas. The forecast rainfall is much needed over the far south central/southeastern counties who remain under D1-D2 moderate to severe drought conditions. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... Widespread VFR conditions prevail as of 01Z Wednesday, with these conditions likely (80-90% confidence) to continue at all airfields outside of BFD through ~12Z Wednesday. In this timeframe, approaching a line of SHRA with embedded TSRA will approach NW PA closer to the ~03/04Z timeframe. This will likely bring low-end VFR to high-end MVFR ceilings which will persist throughout the entire overnight period and throughout much of the evening hours on Wednesday (~22/23Z Wednesday). Closer to the 12Z timeframe, increasing signals for IFR at BFD based on a consensus of HREF ensemble members and multiple cycles of GLAMP model guidance, so have decided to include these in the TAFs with moderate (~40-50%) confidence on timing. A brief period of lower ceilings trending towards LIFR will be possible; however, confidence remains too low for inclusion in the 00Z TAFs. Elsewhere, the aforementioned line of SHRA/TSRA is expected to diminish in intensity/coverage overnight, leading many airfields unlikely to receive any SHRA in the 00Z-12Z Wednesday timeframe. Recent HREF runs have been fairly consistent with the progression of a low-level cloud deck across all of central Pennsylvania, so have included these mentions and slightly adjusted timing based on recent HREF/NBM/GLAMP model guidance in order to outline initial onset of MVFR restrictions. There is high (~70-80%) confidence on SHRA/TSRA reforming during the late morning to early afternoon hours (mainly after 16Z) with increasing coverage into the evening hours. Current SHRA mentions have been included at all terminals across central Pennsylvania based on recent forecast/HREF/GLAMP model guidance with most uncertainty with respect to timing. In terms of TSRA coverage, the highest potential at this time is outlined across SE PA (MDT/LNS) where enough instability will be present in order for some mentions in the TAF. At this time, have trended towards PROB30s; however, if the cold frontal passage trends quicker than forecast, could see mentions removed at MDT/LNS in future TAF packages. Outlook... Thu...Lingering showers across S PA, restrictions possible. Fri...Restrictions likely with rain moving in from south to north, lasting into Fri night. Sat-Sun...Restrictions likely with rain. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ WHAT HAS CHANGED...Steinbugl KEY MESSAGES...Steinbugl DISCUSSION...Steinbugl AVIATION...Beaty