Area Forecast Discussion
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000 FXUS61 KPBZ 250145 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 945 PM EDT Mon Jul 24 2017 .SYNOPSIS... A stagnant mid-level trough will keep very-humid conditions over the region today with a continued threat for showers and thunderstorms. Dry conditions are expected Tuesday through early Thursday. && .NEAR TERM /THROUGH TUESDAY/...
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Drier air is quickly filling into the region in the wake of a cold front that should be exiting the southeastern reaches of the CWA forthwith. That said, steep low level lapse rates do remain in the wake of the front, and stratocumulus has filled in behind it to a degree. This has basically bisected the area along a NW-SE line. To the north of this line, stratus will likely remain the majority of the night, and to the south, clearing may result in some valley fog as winds relax toward morning. Subsidence becomes the dominant player on Tuesday as high pressure moves into the region. Likewise, notable mid-level warming starts to occur, which should quickly eradicate any remnant layers of steepened lapse rates in the column and allow for ample sunshine through the day. Fries
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... Upper-level heights will rise on Tue ahead of a shortwave ridge, and broad surface high pressure will build into the Great Lakes region. The drying boundary layer and overall subsidence will support a dry, seasonable forecast for Tue/Wed. Low-level moisture will begin to increase again Wed, which will help maintain above-average minima despite light wind and increasing cloud cover. && .LONG TERM /THURSDAY THROUGH MONDAY/... Models are consistent for Thu in digging a deep upper-level trough along the Appalachians, which will act on an increasingly-moist and unstable airmass as a cold front crosses the region. Showers and storms along the boundary are highly probable, and PoPs were increased to reflect this expectation. The forecast for Friday into the weekend gets a bit muddy, as the evolution of the upper trough varies among the medium-range models. If the trough progresses sewd, then the weekend is shaping up to be dry and sunny, with seasonable highs. But other model solutions open the upper wave across the Appalachians, keeping the threat for clouds and precipitation (especially over the aforementioned eastern ridges) into Friday and Saturday. With an amplified upper ridge persisting in the wrn CONUS, it is likely that a mean trough will remain over the ern CONUS for the better part of the extended forecast. The net effect will be overall a seasonably-warm and -active weather pattern. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Relatively cool air encroaching aloft from the north will help deteriorate ceilings to IFR by Tuesday morning as low level moisture lingers across the region. These restrictions should be confined to the northern most ports and lower KPIT`s condition to MVFR. Brief MVFR visibility could occur at KMGW and ZZV. Expect conditions to be VFR by Tuesday afternoon as high pressure builds. .OUTLOOK... VFR is expected to prevail through mid-week as high pressure builds maintains over the region. Moisture will return Thu ahead of a sewd- moving trough. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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