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Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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894 FXUS61 KCTP 270002 AFDCTP Area Forecast Discussion National Weather Service State College PA 802 PM EDT Wed Jun 26 2024 .SYNOPSIS... *Showers and thunderstorms with locally heavy rainfall will settle southward to the Mason Dixon line by midnight. *Partly to mostly sunny and less humid Thursday and Friday *Return of summertime heat+humidity will fuel thunderstorms for the last weekend of June; seasonably cooler & dry start to July && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 725PM EDT: Remainder of SVR WW #464 cleared from central PA at this time. Evolution from discrete and training cells to broken and bowing convective line segments occurred over the past 2 hours, with the most intense convection exiting to our east. Hires models show rain and storms progressing from northwest to southeast btwn 00-06Z with a general weakening trend expected as BL stabilizes after sunset. Main question is how much recovery occurs over southern half of central PA this evening, with consensus that it will be hard to destablize sufficiently to support intense convection. Showers and isold tsra should move across those areas late this evening through around midnight with decreasing activity after midnight. As the frontal zone sags southward this evening, we`ll be watching heavy rain potential as southwest to northeast storm motion and slow southward movement of the overall boundary may bring much needed rain to many areas south of I-80. CAMs indicate most numerous showers/storms settle south of the Mason dixon line after 06z. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... Large scale subsidence and the arrival of much drier (less humid) air behind the exiting cold front will lead to fair and seasonable conditions Thursday. Surface high pressure building over the region should result in fair and cool weather Thu night with valley fog formation likely given air/water spreads 20-30 degrees. Partly cloudy and slightly warmer conditions are likely Friday, as low pwats persist over PA and a return southerly flow develops as the surface high passes off the coast. Latest model data suggests some showers and storms may develop Friday night over the western portion of the forecast area. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Latest medium range guidance is showing an unusual lack of spread among its members, all of which track a surface low north of PA Saturday, with a trailing cold front coming through Sat night into early Sunday. The lack of spread with regards to timing of the front, combined with progged GEFS pwats of +2-3SD, supports an increasing confidence in showers/tsra Saturday. A leading warm front could produce showers/tsra as early as Friday night and a slowing cold front could cause convection to linger into Sunday, mainly over the southeast counties. However, ensemble plumes indicate the most widespread convection should occur Sat afternoon and evening. There is some potential for severe wx Saturday PM, as decent mid level flow overspreads an increasingly moist warm sector. Ensemble plumes currently indicate moderate capes in the 1000 J/kg range and model 0-6km shear is in the 35-40kt range. If the cold front slows enough, severe wx would also be possible across the eastern edge of the forecast area Sunday PM. Latest EPS and GEFS both support fair weather with near to slightly below normal temps and low humidity early next week associated with high pressure building east from the Grt Lks. A seasonably cool and dry start to July! && .AVIATION /00Z THURSDAY THROUGH MONDAY/... Storms that moved across northern and central sections of the state have exited to the east. However, southern PA is still relatively unstable and additional storms are moving through PIT now and LBE soon. The storms are expected to hold together at least until they get into JST and perhaps AOO. The wind gusts across the PIT metro area are into the 30s and 40s. So, we have pegged the gusts at 35KT at PBZ for 1 hr (roughly 02-03Z) and 25KT about an hour later at AOO. These storms could weaken some as they move to the east, but will hold together until they get close to MDT/LNS. Winds behind the storms will get light over the NW and (rather widespread) fog and/or stratus is expected to develop in the Alleghenies. We have brought BFD and JST into LIFR around 06-08Z time frame, with these conditions lasting past sunrise at those sites. Downslope and some wind will probably keep IPT/UNV/AOO from getting as bad (low) of conditions overnight. But, some IFR is possible at those locations, too - but only a 50% chc at this point. It has rained, but the wind won`t be as light at those 3 locations. The rain ending later at MDT and LNS will give them a 30% chc at fog bad enough to get to IFR. But, the wind/downslope will keep us from mentioning IFR at those 2 locations overnight/early AM. The wind picks up in the morning everywhere, and ends any flight category reductions at all sites, slowest over JST, of course. VFR then rules thru the end of the TAF period. Outlook... Fri...Generally VFR. Sat-Sun...Thunderstorm impacts possible. Mon...Generally VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/Steinbugl NEAR TERM...DeVoir/Steinbugl SHORT TERM...Lambert/Fitzgerald/Steinbugl LONG TERM...Fitzgerald/Steinbugl AVIATION...Dangelo