Area Forecast Discussion
Issued by NWS State College, PA

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622 FXUS61 KCTP 220358 AFDCTP Area Forecast Discussion National Weather Service State College PA 1158 PM EDT Mon Aug 21 2017 .SYNOPSIS... High pressure moving off the Mid Atlantic coast will bring a warm and increasingly humid southerly flow to the region into Tuesday. A strong cold front will move through the region late Tuesday and Tuesday night. Cooler and drier conditions will return for the second half of the week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Flat upper ridge in zonal flow with several weak shortwaves aloft working on increasing deep layer moisture and moderate instability to produce scattered coverage of showers and storms through late this evening. Activity continues to weaken overall but still some local heavy rainers over the lower Susq River Valley early tonight. Holding onto slight chc pops in most areas for the overnight with additional disturbances working eastward from eastern OH and deep layer moisture continuing to increase in weak boundary layer convergence. Patchy fog expected especially over portions of the Lower Susq. which have had persistent rainfall this evening. Mins will range from the lower 60s north to the lower 70s southeast. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Warm humid day Tuesday. Some issues with the timing of the showers in CAM verse none convective allowing models. Most guidance suggest rain likely and some strong to severe storms possible in the late afternoon/evening. Timing in some CAMS implies earlier convection than non- convective models. The front should bring in much cooler weather Tuesday night. But ahead of it Tuesday will be a warm humid day with a good chance of showers and thunderstorms. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... A strong cold frontal passage late Tuesday (NW PA)/Tuesday night (SE PA) will be followed by a extended period of early autumn-like weather for Wednesday into the upcoming weekend as an anomalously deep sfc low/upper trough slides east across southeastern Canada. Daytime high temps will be about 5-7 Deg F below normal across the Western Mtns on Wednesday, though still just slightly below normal across the SE zones prior to the arrival of the deeper/colder air for the latter part of the week. GEFS mean 850 mb temps will dip about 2-3 deg C in all locations for Thursday-Sunday, leading to max temps averaging 5-10 F below normal (with min temp departures about 10-13F below normal Friday-Sunday) as a large Canadian High Pressure area pushes SE across the Glakes Region and becomes centered over the NE states. Lows Fri/Sat/Sun mornings with high centered overhead, will be dipping into the l-m 40s over the Northern Mountains (and deeper valleys of the Central Mountains) and solidly into the 50s elsewhere. Some of the perennial cold spots near and to the east of KBFD could see readings of 38 or 39F. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/...
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Stubborn scattered showers and thunderstorms continue across Central Pennsylvania at 04z. Most are now moving across the northern tier counties at this time. Areas of fog beginning to develop, with a few areas of LIFR already being reported at KIPT. Overnight, expect widespread MVFR fog, with areas of IFR/LIFR visibilities and ceilings. Morning fog gives way to VFR conditions Tuesday, but widespread TSRA expected during the afternoon and evening. .OUTLOOK... Tue...Patchy AM fog. Afternoon/evening TSRA impacts possible. Wed...AM low cigs BFD/JST, otherwise VFR. Thu-Sat...No sig wx expected.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...Grumm/DeVoir SHORT TERM...Grumm/La Corte LONG TERM...La Corte/Lambert AVIATION...Jung

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