Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 151625 AFDCTP Area Forecast Discussion National Weather Service State College PA 1225 PM EDT Sun Oct 15 2017 .SYNOPSIS... A rather strong cold front will push east through the region late today and early tonight. Blustery and cool weather is in store for Monday. Temperatures will rebound to near normal on Tuesday and continue to gradually rise right into this upcoming weekend, as a large area of high pressure builds east over Ohio Valley and Mid Atlantic states bringing an extended period of dry conditions. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Regional, blended satellite/radar mosaic loop shows thickening clouds and showers spreading across western Lake Erie attm, while a preceding area of strato cu was streaming northeast within a belt of strong llvl warm advection via a 50-60 KT LLJ across eastern Ohio and NW PA. Models generate a few to several hundred J/KG of cape this afternoon into early this evening, so some tall, gusty showers and even a few low-topped TSRA are expected across the NW third to half of the state along and just ahead of the Cfropa. SPC has upgraded a large the previous MRGL Risk area to a SLGT risk, and even extended the MRGL area a few layer of counties further to the SE to near the I-99/RT 220 corridor. Higher Res CAMs data indicates the potentially strong to highly isolated SVR TSRA (with the severe weather threat almost exclusively from straight line wind gusts) to be located near and to the west of a line from KBFD to KDUJ and KLBE at 22Z. This convection may maintain its strength through 00Z Monday before gradually weakening as the front crosses the central counties, then the Susq Valley between 00Z and 04Z Monday. Expect to see a decent amount of sunshine in many locations throughout Central PA and the Susq Valley for much of this afternoon within the unseasonably warm airmass ahead of the Cfropa. Max temps in the low to mid 70s across the nrn and wrn mtns....and 75 to 80F in the central and SE zones look in decent shape ATTM, so no big changes there. QPF should be low in the SE, but up to a half of an inch in the NW. Winds will get gusty out of the SW in advance of the cfront. This is usually means that the convergence along the front will be poor, and dry air may also be worked into the mix. Again, we expect to see the showers dwindle as they move through the CWA from NW to SE this evening. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... After the front clears the area early this evening, the cold NW flow will make quite a dramatic difference in the temps and apparent temp. Again, we have become acclimated (sp?) to the very warm weather as of late. So, a drop to much below normal temps and cold, cross-lake flow and strato cu and sprinkles/light showers will be a shock. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Monday, We`ll see maxes about 5-10F below normal with highs ranging from the U40s to L50s across the mtns, to around 60F in the SE. As the mid-level thermal trough crosses the region Monday, isolated to scattered instability (and lake effect) showers will occur across the NW Mtns and Laurel Highlands, with just some sprinkles accompanying expanding MDT cu clouds in the afternoon elsewhere. A cold night is in store for Monday night/early Tuesday as the center of a 1030 mb high passes near or just to the south of the CWA with clear, and calm conditions with -1 to -2 sigma PWATs. Min temps Tuesday morning are expected to be around -5F degrees below normal. Have increased temps a little based on low cloud presence. However frost across much of Central and Northern PA remains likely with even sub- freezing conditions across the perennial cold spots INVOF KBFD. For the mid to late week period, heights gradually rise with a multi-model consensus indicating a string of dry and increasingly warm days and mainly clear/cool nights. We could have a period true Indian Summer weather with high temps in the 60s to 70s Thursday through Saturday. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... Low stratus was gradually eroding from the north and west, and will be followed by a several hour period of mostly sunny skies across all, but the nw part of the CWA for this afternoon. LLWS at KBFD has turned into more a well mixed, gusty southwesterly flow as of midday, and a somewhat similar increase in the swrly gradient wind will occur across the Central PA airfields. The lingering low clouds, and greater separation from the main core of the strong Swrly low-level jet at 4-7 kft AGL (over far nwrn PA and Lake Erie), will lead to light moderate winds and gusts out of the 200-220 deg range for the rest of this afternoon and early this evening. A sharp cold front will cross the area late this afternoon and this evening, accompanied by showers and isolated strong to potentially severe tsra across the NW mtns of PA, followed by MVFR cigs across the western mountains, as residual low level moisture ascends the Alleghenies. Outlook... Mon...No sig wx expected. Tue...Patchy AM fog possible. Wed-Thu...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert SHORT TERM...Dangelo LONG TERM...Lambert/Ceru AVIATION...Lambert/Gartner is the U.S. government's official web portal to all federal, state and local government web resources and services.