Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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911 FXUS61 KCTP 251826 AFDCTP Area Forecast Discussion National Weather Service State College PA 226 PM EDT Tue Jun 25 2024 .SYNOPSIS... High pressure will drift off of the Mid Atlantic Coast tonight, allowing increasing moisture to return to the region. Heat will build again by Wednesday leading to a chance of thunderstorms by late in the day and Wednesday night as a cold front pushes through the state. Dry weather with comfortable humidity on Thursday and Friday will be followed by another cold front late Saturday or early Sunday of next weekend. && .NEAR TERM /THROUGH TONIGHT/... Extensive mid and high clouds venting from decaying MCS over the eastern GLAKS and OH Valley have been streaming overhead for most of the day. This appears to have shaved 2 to 4 degrees Fahrenheit off of temperature trends, but thinning high clouds may allow mid to late afternoon temps to catch up to overall boundary layer warming and reach within a few degrees of previously forecast highs. We did cut maxes by 3-4 degrees throughout, but the slight increase in dewpoints accompanying slightly higher temps than yesterday (and less of that refreshing breeze) will counteract the underperforming temps. Focus is on moisture and heat return scenario tonight and Wednesday, and resulting complicated convective mode/forecast tonight and Wednesday. We start out with near term CAMs differing wildly on their initialization of the aforementioned ongoing MCS over OH, and how much recovery will be needed in these areas late tonight and Wednesday morning to support potentially another MCS in the Wednesday morning hours that can impact convective evolution Wednesday afternoon and evening. At the very least, a warm front will try to lift northeastward across the Eastern Grt Lks tonight with a few showers and possibly a tsra possible over the west/northwest mountains. Much less certain is the potential for showers or thunder farther east across the Central Ridge and Valley region of the state as the instability axis over Lake Erie, sags to the SE. Again, MCS propogation early Wednesday morning turning "right" towards the WV/MD panhandles can greater influence POPs farther north, and confidence is low on the timing and track of the Wednesday morning MCS. PW surges to between 1.0 and 1.5" by late tonight, at least providing the fuel for potential activity overnight and Wednesday morning. && .SHORT TERM /WEDNESDAY/... The aforementioned surging PWs and falling heights ahead of an upstream cold front will overall bring a much better chance of widespread showers and scattered strong to potentially severe thunderstorms Wednesday afternoon/evening. How we get there is far less certain, owing to the aforementioned uncertainy in MCS formation and track. There is a scenario where the early morning MCS pinches off moisture and instability to areas farther north as it curves southward, stably stratifying much of central PA early in the day and challenging temp/instability recovery ahead of the advancing cold front. Those details will need to play out to give us a better idea of convective setup later Wednesay and Wednesday evening, but the SPC slight risk for southeast and south central PA certainly highlight areas with the greatest threat for strong storms to develop later Wednesday. A ribbon of relatively strong low to mid level (west to southwest) winds of 50 to 55 kts, combined with moderate instability, suggests organized convection and locally severe weather is possible Wed PM. Latest ensemble plumes indicates most likely aerial average rainfall Wed will be between one half and one inch. High temps Wed should reach the upper 70s to low 80s across the Northern Mtns and upper 80s to low 90s respectively across the Central and SE zones. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... After the return of warmer and humid conditions Wednesday, Thu and Fri turn comfortable once again with dewopints dropping back into the 50s (and 40s up north). The rollwer coaster continues by late Friday and Saturday as warmth and moisture return...and it gets hot again on Saturday ahead of yet another cold front. Relief/precip/storms come from a cold front in the middle of the weekend (timing subject to change slightly) and yet another refreshing air mass to arrive Sunday night and Monday to start the month of July. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... High confidence in VFR flying through the evening into the first half of tonight/06Z Wed. Uncertainty ramps up overnight into early Wednesday morning with potential for showers and t-storms moving into the airspace from the north/west. Can`t rule out some cig restrictions in the 06-15Z window based on the latest probablistic guidance, but the overall pattern/low level flow don`t provide a strong enough signal to maintain in TAFs outside of KBFD. Confidence continues to trend lower from late Wed morning through 18Z and beyond given highly conditional/potential strong to severe t-storm scenario. A 40kt low level jet from 230-260 degrees will maintain LLWS at KBFD between 00-06Z. Outlook... Wed...Thunderstorm impacts likely. Thu-Fri...Generally VFR. Sat-Sun...Thunderstorm impacts possible. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/DeVoir NEAR TERM...Lambert/DeVoir/Dangelo SHORT TERM...Lambert/DeVoir LONG TERM...Banghoff AVIATION...Steinbugl/Bauco