Area Forecast Discussion
Issued by NWS State College, PA

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525 FXUS61 KCTP 211724 AFDCTP Area Forecast Discussion National Weather Service State College PA 1224 PM EST Tue Nov 21 2017 .SYNOPSIS...
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Pennsylvania will remain under a mean upper level trough through week, with a succession of shortwaves and accompanying cold fronts pushing southeast across the state.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A gusty southwest return flow and plenty of sunshine will allow temps to recover from a cool start today. The latest models have trended warmer 00Z model soundings become well mixed through at least 925mb, where temps between 6-8C should support highs well into the 50s. For now, have conservatively raised national/superblend numbers by a couple of degrees.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Clouds will increase tonight, as a cold front pushes into the area. Moisture will be lacking ahead of this front. However, impressive large scale forcing ahead of potent mid level shortwave should support a period of light rain changing to snow across the northwest mountains tonight. GFS, NAM and EC all showing a band of 850-700mb fgen forcing within right jet entrance region, resulting in bulk of precip falling in colder air behind surface cold front. With shortwave lifting north of Pa, expect band of rain/snow to diminish as it pushes southeast late tonight, with HREFV3 data supporting only slight chance of measurable precip southeast of the Allegheny Plateau. However, incipient secondary low off the Mid Atlantic coast could clip the southeast counties with a period of rain early Wed morning. A brief period of lake effect snow showers appears likely Wed morning, as a shot of seasonably chilly air works in behind front. However, approach of high pressure and falling inversion heights should result in minimal accums early in the day across the western mountains. For most of central Pa, Wednesday should be dry and breezy with temps below normal. GEFS mean 8h temps between -4C and -9C should translate to highs from the low 30s across the high terrain of northwest Pa, to the upper 40s across Lancaster Co. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... High confidence in fair/chilly weather Wed night and Thursday, when all model data tracks high pressure over the state. Return southwest flow ahead of an approaching cold front should bring fair and milder wx Friday. Relatively good agreement among med range guidance into next weekend, with cold front passage likely early Saturday. Scattered rain showers will likely to accompany the front Sat, followed by another period of lake effect snow showers Sat night into Sunday, as another blast of seasonably chilly air charges across the relatively mild waters of the Grt Lks. ECENS and GEFS both support below normal temperatures Sunday-Monday, as deep upper level trough swings over the northeast states. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/...
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VFR will continue through the forecast period as high pressure slides east of the Carolina coast. Tightening llvl pressure gradient above the decoupled/stable boundary layer will create LLWS across the Western Mtn TAF sites through the mid morning hours Tuesday. Sustained SSW winds of 10-13Kts with gusts into the mid and upper teens area likely Tuesday, thanks to abundant sunshine and vertical mixing up through several KFT AGL. Showers coming in from the west will bring down cigs and vsbys for a period between 03Z to 09Z behind frontal passage. There could be a brief period of rain just ahead of the front but will drop quickly to snow after 05Z. Outlook... Tue night-Wed...Rain/snow showers along and in the wake of a cold front. MVFR likely wrn 1/2. Thu-Fri...No sig wx expected. Sat...Chance of rain/snow showers.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald NEAR TERM...Fitzgerald/Ceru SHORT TERM...Fitzgerald LONG TERM...Fitzgerald AVIATION...Ceru/Gartner

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