Area Forecast Discussion
Issued by NWS State College, PA

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460 FXUS61 KCTP 212203 AFDCTP Area Forecast Discussion National Weather Service State College PA 503 PM EST Wed Feb 21 2018 .SYNOPSIS... A cold front will push southeast across the area this afternoon and evening, then stall out in the vicinity of the Mason-Dixon line or across the Virginias for the remainder of the week into the upcoming weekend. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Cold front working through the Lower Susq Valley at 22Z accompanied by a broken line of convection. No lightning strikes currently, but some modest CAPE noted in SPC mesoanalysis, so will maintain the chance of thunder through 00Z over portions of York/Lancaster counties. A lull in the precip is expected the first part of the night, as dying cold front sags south of the state and high pressure and colder air mass settles in. Precipitation will redevelop late tonight, as a wave along the stalled front ripples eastward. The issue that will arise is the potential for a wintry mix to develop and settle south as colder temperatures return to northern PA. Right now we have an advisory for the northern counties from I-80 northward. The in house HRRR shows mainly freezing rain and sleet as the winter Wx threats while the SPC HREF has a colder solution and brings the chance of freezing rain all the way down to the MD border. Blended MOS hourly temperatures don`t support being that pessimistic at this time so for now we will concentrate the headlines over the northern tier.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... Highs Thursday will be some 30-35 deg colder than today as a big burly high builds to our north and pushes the new chilly airmass south into the Mid Atlantic states. The first wave is expected to slide east with the steadiest precipitation being in the morning, becoming more scattered and showery in the afternoon. There will likely be a prolonged period into early afternoon where temperatures flirting with freezing will keep the threat of sleet/ice/snow as the predominant weather types over the northern 1/3 or so of the forecast area. Right now it looks like a thin coating of ice with perhaps as much as 2-3 inches of snow from Warren County east through Tioga County. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Did not change much for Thursday night into Friday. New 12Z GFS numbers show some sites colder tonight and Thursday night and some warmer. Current fcst looks decent. While it could be a little cooler...we are colder than others by a tad...especially on Friday...so I did not want to go down more at this point. Weekend still looks similar to the last few days. Best chance for a warm up is Sunday...as system lifts to the north and west of central PA. This track is a little further west now...which would keep the heavy rain threat further away from our area. Depending on the mixing...more record highs could occur. Looks dry after Sunday evening. More information below. Forecast for Thursday into Friday looks cloudy and damp with periods of light rain/drizzle and areas of fog. The fog will be locally dense at times, especially on East-Facing slopes and ridgetops during the overnight and early to mid morning hours. Stalled out sfc front across the Virginias and Ohio River Valley and SW flow aloft will be the conduit for a few waves of low pressure to ripple NE along, and bring us this rather dismal weather. There is the potential for a significant change in practical weather...if frontal position changes north or south very much. && .AVIATION /22Z WEDNESDAY THROUGH MONDAY/... A sharp cold front will continue to slide SE across the flying area with VFR dominating the warm air east of the front and MVFR/IFR with scattered rain and showers on the cold side of the front. Some drier air and improved conditions will move in this evening as the front settles south, but will be replaced by lowering ceilings once again between about 06-12Z as a new area of rain overspreads the region. Across the far north a wintry mix of freezing rain, sleet and snow is likely and could last into the early afternoon hours. An active second half of the week follows, as several weak waves of low pressure bringing bouts of rain, and even some light freezing precipitation to the north Thu into early Fri. Outlook... Fri...Widespread restrictions in periods of rain. Some improvement poss SW late. Sat...Rain remains likely. Widespread restrictions north, gradual improvement south. Sun...Widespread restrictions likely in periods of rain. Mon...No sig wx. && .HYDROLOGY... Recent rainfall and snowmelt has resulted in wet soil and well above normal streamflows across much of the area especially south-central PA. Rainfall of 0.50 to 1.00 inch is forecast between Wednesday and Thursday night, with additional rainfall likely into/over the weekend. River flood potential (including small streams, creeks and tributaries) is above normal and we will continue to monitor the risk in the coming days. && .CLIMATE... It Looks like another day of record highs across southern Pa today. Here are current records for today, Wednesday February 21st: MDT: 71/1997 IPT: 69/1930 BFD: 64/1997 AOO: 71/1997 && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 1 AM to 4 PM EST Thursday for PAZ004>006-010>012-037-041-042. && $$ SYNOPSIS...La Corte NEAR TERM...Fitzgerald/La Corte SHORT TERM...La Corte LONG TERM...Lambert/Martin AVIATION...La Corte HYDROLOGY... CLIMATE...

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