Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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000 FXUS61 KPBZ 250755 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 355 AM EDT Mon Mar 25 2024 .SYNOPSIS... Dry and warmer today under high pressure. Rain chances return Tuesday as an upper level disturbance swings through the region. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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KEY MESSAGES: - Dry day. Warmer temperatures. Increasing wind gusts this afternoon. - Limited fire weather threat is expected for West Virginia and eastern OH due to low relative humidity and increasing wind gusts. A Special Weather Statement may be need. ------------------------------------------------------------------- Deep surface high will drift across northern New England today. As this high moves northeastward, an upper level ridges will amplify over eastern PA. This setup will mean plenty of subsidence over the region leading to another dry day with minimal cloud cover. Strong warm air advection will push highs 10+ degrees above normal. With the broad surface high over New England, and a deepening system over the central US, the surface pressure gradient will tighten today leading to increased surface wind gusts this afternoon. Gusts of 20 to 30 mph are possible, with the strongest over the ridges. A very dry atmosphere will remain in place today. RH values may drop into the upper teens to lower 20s over portions of the region this afternoon. Surface winds will also strengthen this afternoon. This will increase the fire weather threat as the day progresses.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... KEY MESSAGES: - Strong wind gusts (over 40mph) due to downsloping along the ridges of West Virginia and Pennsylvania is possible tonight. - Rain chances return to the region Tuesday with an approaching disturbance. - Scattered light showers continue Wednesday with the slow crossing of a cold front. ------------------------------------------------------------------- Upper level ridge will remain parked over eastern PA tonight. This will slow the eastward movement of an upper level wave rotating northeastward on the eastern side of the massive central US trough. This should keep the area dry tonight. A tight surface pressure gradient, and crossing low-level jet, will increase the risk for strong wind gusts over the ridges tonight. Latest probabilities keep the wind gusts just below advisory levels. NBM probs for >40 mph are 40% to 50%, with probs of >45 mph around 15% to 20%. The wind direction may not be just right for optimal downsloping, and it appears a large low level inversion will develop tonight as warmer air continues to push northward aloft. Still seeing some timing issues with the onset of rain on Tuesday and how far east it will push before either stalling or dissipating. The amplified ridge over the east coast will begrudgingly move eastward on Tuesday. The shift will be in response to a shortwave trough that will eject eastward from the central US trough. Much of the energy from the shortwave may be spent fighting the ridge. Models are showing a descent moisture plume passing through the region on Tuesday, which will aid in bring widespread rain to the area. It does appear that as the rain moves eastward, it will decrease in coverage and intensity. Probabilities for >0.25 inches for the eastern half of the forecast area are 40% to 60% while over the western half are 60% to 70%. Looking at probs >0.50 seeing around 15% to 45%, with the higher numbers over Ohio. Rainfall will be generally light with the higher QPF mainly over Ohio. With rain and increased cloud cover, highs on Tuesday will drop a few degrees, but still remain above normal. With the slow eastward movement of a cold front, due to the stubborn east coast ridge, the risk for scattered showers will continue on Wednesday. However, a large upper level dry slot will spread across the region ahead of the front, greatly limiting rainfall amounts. Its not out of the question that much of the rain directly along the front will dissipate Wednesday afternoon. Temperatures remain above normal on Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... KEY MESSAGES: - Dry conditions are favored Thursday and Friday. - Unsettled weather returns for the weekend. ---------------------------------------------------------------- Dry conditions are more likely with the reestablishment of high pressure Thursday and Friday. Although an isolated shower cant be completely ruled out over the ridges on Thursday. Eastern CONUS ridge will try to amplify over the weekend. However, it appears as if we will be located right at the top of the ridge. Shortwaves, riding over the ridge, will keep in the risk for scattered showers both Saturday and Sunday. Above normal temperatures will remain through the weekend. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... VFR will prevail through the TAF period. Tightening pressure gradient will gradually strengthen southeasterly winds through the day. Downsloping is expected to enhance gusts in the LBE area, though a strong inversion and poor low-level lapse rates will likely limit the depth of the boundary layer... keeping strongest winds aloft. Occasional gusts of 10-20 kts are possible during the day, increasing to near 30 kts for LBE by 00z Tuesday. With limited gusts at the surface and a strong LLJ, low-level wind shear will become an issue near the end of the TAF period and into early Tuesday. High clouds will increase today ahead of the next approaching low pressure system. .Outlook... High pressure maintains VFR conditions through tonight with only mid and high clouds expected. Rain and restrictions return Tuesday and Wednesday with the approach and passage of a cold front. VFR then returns Thursday and Friday under high pressure. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...22 NEAR TERM...22 SHORT TERM...22 LONG TERM...Hefferan/22 AVIATION...Cermak/Rackley

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