Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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000 FXUS61 KPBZ 271320 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 920 AM EDT Tue Oct 27 2020 .SYNOPSIS... Light rain chances will continue today with a weak crossing disturbance. Widespread rain is expected Thursday and Thursday night with low pressure. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A rather dreary and stagnant pattern continues across the forecast area. Adjusted temperatures just a degree cooler to account for the persistent cloud cover. Light rain chances continuing to be intermittant through this afternoon and evening will leave a slight to chance of measurable precip. Temperatures continue to be 5 to 10 degrees below normal. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... The last in a series of weak crossing shortwaves, and limited jet ascent, should maintain the patchy light rain chances tonight. Weak sfc high pressure is expected to briefly build across the Upper Ohio Valley region Wednesday, with dry weather expected. A closed upper low is progged to advance out of the Southern Plains Wednesday night and Thursday, as remnant tropical low tracks NE from the Gulf in SW flow ahead of the upper low. The upper low is then expected to phase with a northern stream trough later Thursday and Thursday night as it crosses the Ern CONUS, as the associated sfc low tracks across the Ohio Valley/Mid Atlantic region. The combination of the remnant tropical moisture, and increasing jet and shortwave supported ascent, should result in widespread rain across the region late Wednesday night through Thursday night. At this time, total QPF amounts of 1.5 to 2.5 inches are expected over a 36 hour period. With relatively dry antecedent conditions in place, these amounts should not result in any major hydro issues, though future trends will continue to be monitored. The sfc low is progged to track to the Mid Atlantic Coast Thursday night. Cold advection behind the low could result in some of the rain mixing with snow north of I 80 late Thursday night, though no accumulation is expected. Seasonably cool temperatures are expected through the period. && .LONG TERM /FRIDAY THROUGH MONDAY/... The upper trough should complete its passage Friday, with rain chances diminishing. Dry weather should return Friday night through Saturday night as high pressure builds across the region ahead of a Central CONUS trough. The trough is then expected to cross the region Sunday with low chances for showers. Sfc high pressure building under NW flow aloft should return dry and cool weather for Monday. && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... MVFR stratus is expected for much of the day due to saturated low levels within a somewhat stagnant flow. However, slight sfc high pressure building and increasing lift ahead of an approaching shortwave trough should lift area cigs and could potentially create brief breaks in the low level deck. The passage of the shortwave trough will create areas of light rain/drizzle late today through the overnight period, favoring the I-80 corridor. In addition, top-down moistening plus weak frontal convergence will drop area restrictions overnight, with widespread IFR/LIFR cigs expected. Building sfc high pressure, weak shortwave ridging, and slight dry air intrusion will all help area restrictions improve through the day Wednesday. .Outlook... Widespread restrictions amid light to moderate rainfall is expected Thursday into early Friday morning as tropical remnants pass southeast of the region. VFR conditions should return by Saturday with building sfc high pressure and shortwave ridging. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.