Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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542 FXUS61 KPBZ 011821 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 221 PM EDT Tue Jul 1 2025 .SYNOPSIS... Showers and thunderstorms will continue today with a crossing cold front. High pressure will return dry weather to the region Wednesday. A weak cold front will bring a slight chance of showers and thunderstorms Thursday, before high pressure returns dry and warm weather through Saturday. && .NEAR TERM /THROUGH TONIGHT/...
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KEY MESSAGES: - Shower and thunderstorm chances continue today - Marginal Risk for excessive rain across eastern OH and portions of western PA & Slight Risk for excessive rain over southwestern PA and northern WV - Patchy fog tonight --------------------------------------------------------------- Widespread showers and thunderstorms are expected today ahead of an approaching front and an associated shortwave trough. The latest CAMs indicate the heaviest convection is east of Pittsburgh and in northern West Virginia through mid-afternoon. Behind the heaviest rainfall, light and steady showers are expected. PWATS will generally be lower today for much of the area, with a NW- SE gradient. NW PA should see values around 1.5, with areas across northern WV ranging from 1.8 to 2.0. The increasing flow aloft should result in faster storm motion today, though if any training or backbuilding occurs a localized flash flood potential is possible. The surface cold front is forecast to approach the region toward evening, decreasing available moisture and instability. This will create an unfavorable environment, weakening any potential convection along the front. Once the front has passed, the clearing sky along with nearly calm wind and moist ground could lead to some patchy fog tonight.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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KEY MESSAGES: - Dry Wednesday - Slight chances for showers and thunderstorms Thursday - Temperatures a few degrees above average. ---------------------------------------------------------------- The fog should quickly mix out and dissipate Wednesday morning. Dry weather is expected through Wednesday night as a ridge of surface high pressure builds across the Upper Ohio Valley region. A trough and its associated surface cold front, is expected to track southeastward across the Upper Ohio Valley region on Thursday. Very dry air aloft will likely inhibit updraft growth, inhibiting the chance for severe weather while limiting the chance for showers and thunderstorms. Temperatures should continue to average a few degrees above seasonable levels through the period.
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/...
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KEY MESSAGES: - Dry through the first half of the holiday weekend - Increasingly hot and humid with shower and thunderstorm chances returning Sunday and Monday ------------------------------------------------------------------- Friday and Saturday, a ridge is forecast to shift eastward resulting in dry and warm weather across the Upper Ohio Valley region. The ridge is then progged to flatten Sunday into early next week, with westerly flow aloft across the Upper Ohio Valley region. Disturbances embedded in this flow aloft are expected to periodically cross the region, with daily shower and thunderstorm chances returning. Even as the ridge flattens, 500 mb heights are still expected to be approach 590 dam, bringing hot and humid conditions across the region. High probability (70%-90%) of maximum temperatures at or above 90 degrees on Sunday and Monday.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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Exiting showers and thunderstorms along a pre-frontal trough will leave areas of lighter rain over the region through 23z; additional shortwave movement may create localized enhancement of rainfall rates that could briefly drop visibilities to MVFR/IFR. Otherwise, lowering precipitation trends will favor VFR improvements through 00z. The degree of cloud clearing overnight will dictate the extent/spread of low IFR/LIFR fog stratus as the surface cold front remains NW of the region. Latest high resolution modeling continues to suggest a 50-70 percent probability for visibilities below 3SM, with only about a 10 percent reduction for seeing visibilities below 1SM. Though river valley locations and locales SE of Pittsburgh are likely to see these restrictions, there is less certainty in whether fog/low stratus becomes widespread to impact harder-to-fog terminals like KPIT/KZZV/KBVI. Diurnal heating/mixing with the NW wind shift after the cold frontal passage should return VFR areawide by Wednesday afternoon, save for initial CU development that may be sct/bkn below 3kft. Outlook... Subtle shortwave movement could generate an isolated shower with the residual moisture east of KPIT, otherwise VFR is favored. Very localized river valley fog southeast of KPIT can`t be ruled out early Thursday morning. Additional shortwave movement within northwest flow may create isolated to scattered showers and thunderstorms Thursday into Friday. Brief ridging aloft and surface high pressure favors dry weather Saturday before storm chances return early next week.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...WM NEAR TERM...WM/Lupo SHORT TERM...WM/Lupo LONG TERM...WM/Lupo AVIATION...Frazier