Area Forecast Discussion
Issued by NWS State College, PA

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096 FXUS61 KCTP 230935 AFDCTP Area Forecast Discussion National Weather Service State College PA 535 AM EDT Sat Sep 23 2017 .SYNOPSIS... A ridge of high pressure at the surface and aloft will keep the region dry through at least the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... Fewer high clouds over top of the region tonight so temperatures are falling and night time blended satellite images are starting to show some valley fog forming over the Northern Mountains as well as portion of the Central Mountains. After the early morning fog dissipates, another dry and unseasonably warm day with comfortable humidity is in store for the forecast area as the broken weather record keeps playing the same song. The recent spell of very dry weather where we have seen no significant rain for the last 2 weeks seems to be starting the stress local vegetation with many trees locally beginning to shed their leaves. Seems a little early. Tonight...more of the same, though temperatures will trend several degrees warmer as humidity begins to make a rebound. && .SHORT TERM /SUNDAY/... Sunday will continue the rain free portion of the forecast with unseasonable warmth, however guidance is consistent in bringing in some summer-like dewpoints, making it noticeably humid by Sunday afternoon. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... The large blocking high is made to remain over the region through early next week as the remains of Jose continue to weaken, with the models showing the circulation eventually either dissipating or getting absorbed into the northern periphery of the slowly advancing Hurricane Maria off the SERN US coastline. Shortwave energy is eventually made to track east through SRN Canada causing our upper heights to begin falling by Wednesday. At the same time Hurricane Maria is forecast to be moving northward off the eastern seaboard. Models are trending closer to the coast by the Wednesday-Thursday timeframe with several members of the ECENS/GEFS actually bringing the storm very close to or even hitting Cape Hatteras, before finally recurving the storm out to sea south of the 40th parallel. The main issue locally is whether we see any kind of marine influence possibly bring some light rain/drizzle into my eastern zone for Wednesday as is suggested by the ECMWF. While the latter portion of the forecast will depend on just how fast Maria moves north as the upper shortwave approaches the area from the north, I used the blended MOS to put low chance POPs in the forecast starting Wednesday. From that point it`s still uncertain how fast and deep the northern stream shortwave ends up being. There is reasonable agreement through Thursday before the GFS speeds up and deepens the wave through the area Friday. The ECMWF and the GEFS are slower and less amplified, holding the most significant troughing off until the weekend with a cooler showery pattern. The bulk of the extended will be much warmer than normal, a true late season visit from summer, before the pattern turns cooler to end the new work week. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
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Still no fog as of 530 AM. No big changes to 09Z TAFS. Dewpoints lower than in recent days, so fog is less likely this morning. More detail below. High pressure will remain over Pennsylvania today, ensuring VFR conditions and light wind for most of the area. The only issue will be some patchy valley fog during the early morning hours. The air mass is a bit drier than yesterday, so expect fog to be confined to the deep river valleys north of I-80, likely leaving the central PA airfields unaffected. Can`t rule out a brief reduction at KBFD or KIPT around dawn, but believe the odds are below 50 pct based on a combination of conditional climatology, SREF prob charts and MOS guidance. .Outlook... Sun-Wed...Patchy AM valley fog possible, mainly northern PA.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...La Corte AVIATION...Martin

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