Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 161607 AFDCTP Area Forecast Discussion National Weather Service State College PA 1107 AM EST Mon Jan 16 2017 .SYNOPSIS... High pressure will drift east and off the Mid Atlantic Coast today. A warm 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 follow and bring mainly dry conditions with temperatures several degrees above normal from the middle of the week into the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Surface high over SERN Pa will provide the region with mainly fair and dry weather through much of today. However warm advection is already making itself felt with a shield of clouds that is steadily progressing eastward from the complex frontal system moving through the central part of the country. There is a slight chance for some light rain across the SW part of the Forecast Area late this afternoon, but most locations will remain dry. The cold start to the day and thickening cloudcover throughout the day will hold temps lower by several degrees compared to earlier guidance that suggested more sunshine. Highs will be mainly in the mid 30s to mid 40s for the bulk of the forecast area. && .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 /16Z MONDAY THROUGH FRIDAY/... Low cigs remain over the SRN portion of the flying area as a weak SSE low level flow has kept the moisture locked in over the area. The MVFR ceilings will slowly lift through early afternoon, but overall trend will be for more cloudiness to increase from the west as a frontal system takes aim at the area. Restrictions are likely to develop/return during the evening with widespread MVFR to LIFR conditions a good bet late tonight into Tuesday. Rain will gradually spread across the airspace with risk for freezing rain mainly over the northern 1/2 of the airspace between 05-15Z Tue. 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...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...Lambert/Gartner AVIATION...La Corte/Steinbugl

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