Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 171735 AFDCTP Area Forecast Discussion National Weather Service State College PA 1235 PM EST Wed Jan 17 2018 .SYNOPSIS... High pressure will build into the region this afternoon through Thursday, bringing clearing skies but cold temperatures. Temperatures will moderate to near normal Friday, then climb into the 40s or about 10 degrees above normal over the upcoming weekend with mainly dry weather continuing. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Some lingering flurries are falling over the western higher elevations where satellite shows some low clouds that look very thin in the high resolution GOES R visuals. Strong, deep-layer subsidence beneath left entrance region of a SW upper jet will combine with a light-moderate westerly surface flow of much drier air to bring clearing and several hours of sunny skies to the Central Mountains this afternoon. Overcast skies in the east will gradually improve as ceilings rise above 100,000` during the afternoon with some sunshine later in the day. Ensemble mean 925mb temps of around -13C support highs this afternoon ranging from the mid teens across the Western Mountains, to the mid 20s over the Susq Valley. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Periods of strato cu and brief flurries will linger across The Western Mtns early tonight, with just some sct-bkn alto cu clouds afterward across much of the CWA. Low temps tonight will vary from near 5 above zero across the perennial cold spots of the NW Mtns, to the low to mid teens across the Southern Valleys of PA. Mostly sunny skies will occur Thursday with temperatures rebounding to near or slightly below normal. Westerly sfc flow will freshen during this short term period, and will gust between 20-25 mph tonight (mainly over the western mtns). Gust potential will increase to 30 to 35 mph Thursday across Central and Western parts of the CWA as high pressure builds over the Lower Ohio Valley and SE States, while a strong North- South pressure gradient resides across the Midwest, Great Lakes Region, and Upper Ohio Valley into PA. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... The medium range will feature a fairly long period of dry- tranquil weather with soon to moderating temperatures. A milder westerly flow will develop to close out the week as a surface high slides along the Gulf coast toward the SERN US. By Friday...WSW flow will push daytime highs above freezing over most of the forecast area, and temperatures are expected to continue to creep upward into the weekend. Temperatures by the weekend will be well above normal under the building eastern ridge. The next chance for precipitation looks to not be until later Saturday into the overnight with a surge of warm advection that is made to develop with the approach a warm front that should slide up to our west into NY state. The chance of showers favoring mainly western areas will continue through Sunday. There is remarkably good agreement at this range in dragging a significant cold front through the area Monday afternoon or evening. The GEFS takes the best PWAT anomaly up through the eastern lakes mainly west of the CWA and right now shows a generally light-moderate rain event. Of course any kind of warmup accompanied by rain will create ice-jam and flooding concerns so that looks to be the next big threat moving forward. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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There is some lingering MVFR/IFR over my western higher elevation terminals with even some very light snow causing visibilities under 2 miles at JST. Drier air will limit the extent of the low clouds moving out of the mountains, but these high elevation sites may be stubborn to improve despite an overall fair weather pattern. It will become breezy, especially over the SE with gusts in the 10-20 mph range. Outlook... Thu...Mainly VFR. Breezy. Fri-Sun...Mainly VFR.
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&& .HYDROLOGY... The threat of ice jamming is diminishing. Dry and colder weather into mid week will form additional ice as stream flows and open channels decrease. Another warm up is expected by the end of the week into the weekend with rain to accompany a frontal system early next week. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...La Corte/Lambert AVIATION...La Corte/RXR HYDROLOGY...

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