Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 160938 AFDCTP Area Forecast Discussion National Weather Service State College PA 438 AM EST Mon Jan 16 2017 .SYNOPSIS... High pressure will drift east and off the Mid Atlantic Coast today. A frontal frontal system will drift slowly northeast across the region Tuesday, followed by a cold front pushing east through the state Tuesday night and early Wednesday. High pressure will move northeast from the Tennessee valley and bring mainly dry conditions with temperatures several degrees above normal. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1032mb surface high pressure over Southeastern Pa will provide the region with fair and dry weather through much of today. a rather thick Cirrostratus/Altostratus layer streaming across much of southern Pa will hold temps up (in the 20s) down there, while much thinner cirrus across most of central and NEPA has allowed temps to fall into the mid and upper teens in many locations. Clouds will steadily thicken-up/lower during the day today as the crest of a flat upper level ridge moves NE across the Ohio River Valley and the mean 925-850mb flow backs to the WSW. This will push a sharp gradient of increasingly higher Theta-E NE across all of the CWA (except for the Northern Tier the state) by 00Z Tuesday. There is a slight chance for some light rain or drizzle across the SW part of the Forecast Area late this afternoon. The cold temps early this morning, and thickening cloud cover throughout the day will hold temps lower by a few to several deg F compared to earlier forecasts and model guidance. Highs will be mainly in the mid to upper 30s for the bulk of the forecast area, while some cooler readings will be found across the mtns of central and northern PA, and some higher readings across our far SW zones. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... The stubborn trough/upper low over the west coast will weaken and lift across the southern plains into the Great Lakes region as a pattern change begins. A good portion of the upcoming week is shaping up to be mild and showery (especially Tuesday) as the bulk of med range guidance shows a ridge slowly retreating off the East Coast as remnants of that west coast low get picked up by the northern stream and track across PA during the midweek. A warm front will be advancing northeast over the area early tonight, spreading a shield of thick altostratus and nimbostratus across central Pa. The strongest WAA is still indicated across western PA toward the end of the day/this evening, where scattered showers are possible. Further south, an increasingly moist southeast flow at low levels, will likely create some drizzle over the higher terrain of Somerset/Bedford counties. A combination of the NAM and NBM were used to paint hourly and low temps tonight. This greatly assisted in depicting the area where light ice accretion is likely later tonight through the mid morning hours Tuesday and the Areal Extent and duration of a recently issued Freezing Rain Advisory. Shield of mainly light rain overspreading the region from the SW tonight will initially fall into very dry LLVL air. This will allow temps to wet bulb down to the u20s and lower 30s over much of central and northern PA changing the rain to mainly light freezing rain between midnight and shortly after sunrise Tuesday. For midday Tue into Tue night, deep southerly flow ahead of that trough will bring a plume of anomalous PWATS over the region which supports the idea of showery (periods of steady rain on Tuesday) and mild weather. As has been the case frequently lately, the GFS brings the trough through faster than the ECMWF. Followed close to the Nat`l Blend of models vary high, 90-100 pops for Tuesday surround on either side by mainly likely pops. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Winds turn westerly behind the system by Wednesday morning as flow turns more zonal, but with no real cold air in sight, temps will remain on the mild side and above freezing during the day. Ridge re-establishes itself over the eastern U.S. for late in the week, as mild SW flow persists over the midwest. Guidance suggests energy will dive south along the west coast eventually helping to strengthen the building upper ridge over the east. We`ll be on the eastern side of this, so subtle shortwaves sliding into the Midwest will bring varying amounts of cloudiness to the west (less in the east) with low end chances for light showers. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... VFR flying today with clouds thickening and cigs lowering through the afternoon. Restrictions should develop around 16/00z with MVFR to IFR conditions good bet tonight into Tuesday. Rain will spread across the airspace late tonight through Tuesday with risk for freezing rain mainly over the northern 1/2 of the airspace btwn 00-15z Tue. Plan to add RA/FZRA groups with the 16/12z TAFs. Outlook... Wed...MVFR/IFR west; MVFR central to VFR southeast. Rain showers west ending Wed ngt. Thu-Fri...No sig wx. && .CTP WATCHES/WARNINGS/ADVISORIES... Freezing Rain Advisory from midnight tonight to 10 AM EST Tuesday for PAZ004>006-010>012-017>019-037-041-042-045-046- 049>053-058. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert SHORT TERM...Lambert LONG TERM...Lambert/Gartner AVIATION...Steinbugl

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