Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 190634 AFDCTP Area Forecast Discussion National Weather Service State College PA 134 AM EST Sun Feb 19 2017 .SYNOPSIS... An extended period of mild, spring-like weather with above normal temperatures is expected through the end of the upcoming week. A weak cool front will push through the state late Tuesday and Tuesday night, possibly accompanied by a few light showers. A better chance for showers will come Friday and Saturday. && .NEAR TERM /UNTIL 10 AM THIS MORNING/... Early morning Water Vapor loop and regional 88D radar mosaic loop shows two features of interest for central Pa today. The first is an upper low tracking across the southern Appalachians. Radar trends and near term model guidance indicate the northern edge of showers/steady light rain associated with this system should stay just to the south of the Mason...Dixon line through Daybreak Based on latest, 05Z HRRR, will maintain a very low chance of measurable rain south of the turnpike and west of Chambersburg through 15z. The Second feature of interest is approaching shortwave over the Upper Great Lake region early this morning. This feature will help to push a weak back door cold front into Pa today. Skies early this morning will range from mostly clear across northern Pa, to mostly cloudy across the south. An active westerly breeze should hold temps up over most of the area through the mid morning hours today. Readings at dawn are expected to range from just the upper 30s north to the mid and upper 40s across the south. && .SHORT TERM /10 AM THIS MORNING THROUGH 6 PM MONDAY/... Upper low and associated threat of showers should have passed east of the region by shortly after 12Z Sunday. However, based on upslope flow and nearly saturated soundings below 850mb, can`t rule out a bit of drizzle over Somerset Co to start the day. A weak back door cold front will deliver slightly cooler air, but it will still be much warmer than normal. GEFS mean 850mb temps about 2-4C cooler than today, likely translating to maxes from around 50F over the northern tier, to the low and mid 60s in the southern valleys. Model soundings suggest Sunday could dawn a bit gloomy over the NW Mtns/Laurels with low level moisture/upslope flow beneath inversion resulting in low clouds. However, SREF probability data strongly suggests these low clouds mix out by midday, resulting in mostly sunny skies across the entire region for the afternoon. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The mild temperatures will continue through the extended forecast as no cold air push is in sight. High temperatures in general will be 10 to 20 degrees above normal with min temperatures mainly above freezing. a rather strong ridge builds in for early next week. Surface ridge axis splitting the region will bring a bit of northerly/ northeast flow to eastern sections, suppressing temps a bit (but still remaining well above average). Weak system slides by to the north Tue night, and brings quick chance for showers. Flow turns SW by Wed as temps rebound. Pattern becomes more amplified late week as a system over the central plains deepens and lifts into the Great Lakes. Clouds will increase late week, with warm front lifting through Thu into Fri - bringing increasing rain chances heading into the weekend. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Guidance trend has been too bullish for sub-VFR cigs over the western 1/2 of the airspace, with dry air/large T-Td spreads keeping cigs AOA 10kft. Therefore 06/19z TAFs are more optimistic with prevailing VFR through the period. MVFR cigs and -RA near KMGW/K264 should remain south of PA/MD border, but did include BKN050 group at JST to reflect some lowering of clouds toward daybreak. Surface wind gusts up to 20kts from 250-280 degrees from mid morning through the afternoon. Backdoor cold front may bring some lower cigs into the northeast 1/2 of the airspace after midnight into early Monday morning. Outlook... Mon...VFR/No sig wx. Tue-Thu...Sub-VFR psbl with chance of rain showers. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert SHORT TERM...Lambert LONG TERM...Gartner/RXR AVIATION...Steinbugl

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