Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 270326 AFDCTP Area Forecast Discussion National Weather Service State College PA 1126 PM EDT Wed Jul 26 2017 .SYNOPSIS... A cold front will push across the area Thursday night and Friday morning. The front will likely stall along the Maryland border for Friday. Heavy rain is possible Friday and Friday night. A much cooler airmass will overspread the commonwealth over the weekend and dry and slightly cooler than normal weather will last into mid-week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Satellite imagery at 02Z showing cirrus of varying opacity covering central Pa in region of WAA aloft ahead of approaching trough. Some thin spots noted upstream, but expect a mostly cloudy night on balance based model rh time sections. Band of showers associated with dying cold front over southern Ontario is progged to remain north of the forecast area overnight. However, stratus and potentially some spotty drizzle is expected to develop over the higher terrain of northeast Pa late tonight in response to moist southerly flow and associated orographic lift over the Poconos. Model soundings show a nearly saturated 0-1km layer by dawn over the high terrain of Sullivan county. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Thursday is likely to dawn gloomy over parts of the region, especially the northeast portion of the forecast area. However, model soundings indicate low level cloudiness will mix out to party sunny skies by midday. Diurnal heating of marginally unstable air mass, combined with passage of shortwave during the PM hours, should produce isolated to scattered thunderstorm coverage during the afternoon and evening hours. Have placed the highest POPS across the eastern counties, where CAPE the highest, and also in the vicinity of weak frontal boundary along the NY/PA border. Despite decent 0-6km shear, lack of much instability is limiting the severe weather threat to marginal. As surface high drifts off the east coast, return southerly flow will advect much higher humidity into the area Thursday. Model 850 temps support seasonal max temps in the upper 70s to mid 80s from north to south. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Main story in the long term is the change from a muggy, stormy, and wet day on Friday to a very dry and fair pattern for the rest of the term. A strong short wave trough is slated to push across the Great Lakes and Ohio Valley Friday. This should help to deepen at least one ripple of low pressure along an old front. The front will be over srn PA or MD at first and heavy rain is possible. WPC hydro outlook for Fri-night is for a SLGT risk of excessive rainfall. QPF from some output is over 3 inches total for the southern third to half of the area. Plumes from GEFS have averages of at least 2 inches there. Lighter amounts are fcst for the northern half of the area. Convection and mean westerly flow aloft and light winds at the low levels seem likely to produce much higher point amounts. The trough rounds the base of a long-wave trough after it passes our longitude, and clears things out nicely. This should happen sometime Sat. Will linger POPs in the S for the day Sat, but go very dry and sunny/clear for the next 2-3 days. Scattered diurnal convection may then start to pop up - esp in NY state Tues/Wed. But, the risk of a shra/tsra in PA is very low until at least Wed as the humidity rises back to more-August like values. && .AVIATION /04Z THURSDAY THROUGH MONDAY/...
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Widespread VFR expected for much of the overnight. Some fog possible late tonight, but clouds may limited fog to the southeast. Some chance of showers and storms on Thu, but nothing widespread. Used VCSH for now. More widespread showers and storms on Friday will be possible. .OUTLOOK... Fri...Scattered SHRA north with more numerous and heavier SHRA/TSRA across the south. Sat-Mon...No sig wx.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald/Martin LONG TERM...Dangelo AVIATION...Gartner/Martin

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