639 FXUS61 KCTP 230322 AFDCTP Area Forecast Discussion National Weather Service State College PA 1122 PM EDT Sun Jun 22 2025 .SYNOPSIS... * Significant and dangerous heat wave continues through Wednesday with major to extreme heat risk for all of central Pennsylvania. * Clear skies for the next couple of nights with little relief from the daytime heat. * Increasingly unsettled mid-to-late week with daily chances for soaking downpours and thunderstorms as heat slowly breaks. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Skies have cleared out early this evening, with high confidence in clear skies overnight across all of central Pennsylvania into Monday morning. Clear skies will allow for radiational cooling and undercutting of NBM temperatures overnight, with low temperatures ranging from the upper 60s across higher elevations of western Pennsylvania to the mid-70s across the Lower Susquehanna Valley. Light winds will also be present overnight; however, fog formation seems very unlikely at this time given relatively dry air in the lower levels. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Plenty of sunshine, humid conditions, and well-above normal temperatures will remain the story of the short-term with dry conditions and sunny conditions outside of afternoon stratocumulus clouds. Ample daytime heating with dewpoints likely reaching into the 60s and 70s during daytime heating will allow for heat index values to reach above the century mark with many locations across the Susquehanna Valley reaching close to/above 105F. No changes to heat headlines for the evening package, keeping the Extreme Heat Warning as-is now through Wednesday. In terms of low temperatures, little relief is expected Monday and Tuesday nights, with low temperatures generally in the upper 60s (NW PA) to the mid-70s across the Lower Susquehanna Valley. It will be important for those with heightened susceptibility to heat, such as young children, older adults, people with chronic medical conditions, and pregnant women, to take action now and make plans to limit time outdoors, wear light clothing, and have plenty of water on hand this week. Another factor to consider will be lack of acclimation to the warm temperatures given recent cooler weather. Stagnant air, coupled with the aforementioned hot temperatures, across the Lower Susquehanna Valley and portions of the Laurel Highlands will lead to development of surface ozone, resulting in poor air quality. The PA DEP has issued a Code Orange Air Quality Alert Day (see AQACTP) for the typical LSV zones (Dauphin, Lebanon, Cumberland, Lancaster, and York counties) along with Blair and Cambria counties for Monday. The short-term will also remain fairly dry with little moisture in the way for work with for shower/thunderstorm development in the afternoon hours on Monday and Tuesday. Low-level moisture does begin to increase on Wednesday with relatively higher chances coming during the afternoon and evening hours across north/western Pennsylvania with an approaching cold front. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Evening Update: Little change with respect to the evening update, as the unsettled pattern continues into the first half of the weekend with slightly lower chances for precipitation coming on Sunday. Previous Discussion: Issued 4:13 PM EDT Sunday, June 22, 2025: Increasing low-level moisture under northwesterly flow begins later on into Wednesday. NBM PoPs increases into the 30-60 pct range Thu afternoon as a slow moving cold front approaches southern New York State and stability begins to erode, with increased chances coming on Friday with ample lift and low-level moisture over central Pennsylvania. Predictability further out into Friday and Saturday remains low with a decent spread in model guidance, thus have leaned on NBM PoPs in this timeframe, with highest chances in the afternoon/evening hours. Repeated bouts of heavy rainfall during the middle and end of the week may result in flooding concerns, particularly if the steering flow lines up parallel with thermal boundaries. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... Widespread VFR conditions through Tuesday across central PA. With temperatures and humidity on the rise, please be mindful of the impact of hot and humid weather on density altitude. Outlook... Tue...VFR. Hot. Wed...Mainly VFR with increasing chances of SHRA/TSRA, especially north. Thu-Fri...Increasing impacts from SHRA/TSRA. && .CLIMATE... With a heat wave starting on Sunday and lasting into the middle of next week, some locations may reach or exceed the daily record hi/max and hi/min temperatures. Record temperatures are most likely on Monday morning through Wednesday morning (to include high and low temperatures records). && .CTP WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM EDT Wednesday for PAZ004>006-010>012- 017>019-024>026-033>035-037-041-042-045. Air Quality Alert from 10 AM to 8 PM EDT Monday for PAZ024-025- 057-059-063-065-066. Heat Advisory until 10 AM EDT Monday for PAZ027-028-046- 049>053-058. Heat Advisory from 8 PM Monday to 8 PM EDT Wednesday for PAZ027-028-046-049>053-058. Extreme Heat Warning from 10 AM to 8 PM EDT Monday for PAZ027- 028-046-049>053-058. Extreme Heat Warning until 8 PM EDT Wednesday for PAZ036-056- 057-059-063>066. && $$ SYNOPSIS...NPB NEAR TERM...NPB SHORT TERM...NPB LONG TERM...Colbert/NPB AVIATION...Colbert/Bauco/RXR CLIMATE...Banghoff