FXUS61 KCTP 190824 AFDCTP Area Forecast Discussion National Weather Service State College PA 424 AM EDT Tue May 19 2026 .WHAT HAS CHANGED... * Increasing odds for a noticeably cooler and rather wet start to Memorial Day weekend && .KEY MESSAGES... 1) Summerlike heat wave peaks today with record challenging temperatures in the mid 80s to mid 90s 2) Scattered strong to severe thunderstorms are possible across north central PA later today/tonight and south central PA Wednesday afternoon 3) Major cooldown arrives Thursday and lasts into Memorial Day weekend with widespread soaking rainfall likely Friday and Saturday && .DISCUSSION... KEY MESSAGE 1: Summerlike heat wave peaks today with record challenging temperatures in the mid 80s to mid 90s Another scorcher today with max temps 85-95F approaching daily records (see climate section). Max heat indices are fcst to reach the upper 90s or just shy of heat advy criteria across the LSV. Record hi minimum temps are also on the table today and Wednesday. -------------------------------------------------------------- KEY MESSAGE 2: Scattered strong to severe thunderstorms are possible across north central PA later today/tonight and south central PA Wednesday afternoon Moist and unstable pre-frontal airmass will be supportive of widely scattered thunderstorms this afternoon through the evening. However, marginal deep layer shear values suggest the primary severe risk is probably later tonight over the NW/NC mtns ahead of the sfc cold front crossing Lake Erie. Convective focus shifts to south central PA on Wednesday with narrow plume of weak to moderate CAPE fcst ahead of the aforementioned cold front. Steep low level lapse rates may support a few instances of strong to severe winds. The magnitude & location of the severe threat will be highly dependent on CFROPA timing and amount of cloud cover. SPC MRGL risk (level 1/5) covers the southeast half of the CWA where max temps are fcst btwn 80-90F. ----------------------------------------------------------------- KEY MESSAGE 3: Major cooldown arrives Thursday and lasts into Memorial Day weekend with widespread soaking rainfall likely 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 southeast half of the forecast area. 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 type event heading into Memorial Day weekend. We may not be bearish enough on daytime temperatures. It also appears probable that periods of soaking rain will dampen at least the start of the holiday weekend. WPC 48hr QPF amounts are quite wet with a widespread 1-2.5 inches fcst from 12Z Friday to 12Z Sunday. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... Prevailing VFR is favored through the 06Z TAF period, with the main exception being visibility restrictions in any heavier showers/thunderstorms that develop. A decaying shortwave moving across the Ohio Valley may initiate additional spotty showers/thunderstorms over Central PA overnight; nonetheless,a lull in convection is expected as forcing lessens through the morning. Otherwise, marginal LLWS is expected to continue through sunrise as surface winds have diminished in the evening while winds approach 40 kts within the lowest 2000 ft. Chances for spotty showers/thunderstorms will pick up again Tuesday afternoon and evening, primarily between 16Z-00Z, as weak shortwaves move around the periphery of a Western Atlantic ridge. Like yesterday, gusty winds may accompany these spotty showers/storms given the moderately unstable airmass (HREF mean SBCAPE around 1000-1500 J/kg) and steep low-level lapse rates (>8 C/km) in place. Most convection will diminish after 00Z Wednesday with the loss of daytime heating, though some models are hinting at an MCS from the Ohio Valley holding together until reaching KBFD around 03Z-06Z Wednesday, potentially bringing gusty winds and visibility restrictions. MCS timing/impacts will be sensitive to how it evolves across the Ohio Valley during the afternoon & evening, with TAF mentions not included at this time given high model variability. Outlook... Wed...Restrictions probable through Wednesday night with widespread showers/storms along CFROPA. Thu...Lingering showers across S PA, restrictions possible. Fri...Restrictions likely with rain moving in from south to north, lasting into Fri night. Sat...Restrictions likely with rain. && .CLIMATE... The following climate sites across central Pennsylvania set new daily high temperature records for May 18th: * A record high temperature of 92 degrees was set in Altoona, breaking the previous record of 91 degrees initially set back in 1962. This record was tied two times previously, back in 1996 and 2017. * A record high temperature of 86 degrees was set in Bradford, breaking the previous record of 85 degrees set back in 1962. ** Note: The high temperature for State College will be reported around 7AM on 5/19. This is due to the State College CO-OP observations running 7AM-7AM. Thus, today's (5/18) high temperature will be reported in tomorrow's (5/19) observation. This record, for reference, is 92 degrees set in 1962. --------------------------------------------- Abnormally warm temperatures will continue on May 19th, thus multiple sites could challenge daily record high temperatures. Daily Maximum High Temperatures for May 19th: * Harrisburg: 95F set in 1962 * Williamsport: 96F in in 1996 * Altoona: 92F set in 1996 * Bradford: 85F set in 1962 * State College: 92F set in 1934, tied in 1996. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ WHAT HAS CHANGED...Steinbugl KEY MESSAGES...Steinbugl DISCUSSION...Steinbugl AVIATION...Teare CLIMATE...Beaty