Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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374 FXUS61 KPBZ 122328 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 728 PM EDT Sat Jul 12 2025 .SYNOPSIS... Hot and humid weather is forecast with with isolated showers/storms this afternoon and evening. A frontal passage on Sunday brings a bit higher risk for severe storms and isolated flash flooding, with muted heat. A relatively drier period is forecast next week with another heat concern by midweek. && .NEAR TERM /THROUGH SUNDAY/... KEY MESSAGES: - Hot; high temperatures climb into the 90s and heat indices approach 100 degrees in spots - Isolated thunderstorms possible this evening into tonight, especially across east-central OH - Storms will be capable of producing damaging wind gusts and localized flooding issues in heavy downpours --------------------------------------------------------------- 500mb heights remain elevated over our region this afternoon, as we remain in the warm sector of surface low pressure over the northern Great Lakes. The main initial impact is the heat this afternoon. 850mb temperatures climb to around 19C this afternoon, supporting high temperatures in the lower 90s. Combined with dewpoints in the lower 70s, heat index values of 95 to 100 are forecast, highest in valley and urban locations. Portions of eastern OH, the lowlands of northern WV, and far southwest PA will likely see low temperatures of 70 or higher tonight (>50% chance), offering little relief. The elevated 500mb heights suggest lesser initial coverage of popup showers/storms into early afternoon due to mid-level subsidence, especially in southwest PA/northern WV. PIT ACARs soundings support this, showing a skinny CAPE profile and relatively warm mid-level air. Low-level convergence near the ridges may allow for an isolated storm or two, although CAMs suggest most of this remains to our east. In eastern Ohio, on the western side of the ridge, isolated coverage is possible during the early to mid- afternoon hours. Any storm that manages to form and produce a strong enough updraft may be able to tap into 800-1000 J/kg of DCAPE, suggesting a downburst wind threat. This is conditional on storm development, which is still in question, but the SPC marginal severe risk still seems justified. The evening hours may allow for a slightly better severe threat in eastern Ohio. Storms have already fired in northwest Ohio ahead of an eastward-moving outflow boundary. This boundary will be moving into an environment with 2500-3000 J/kg of surface-based CAPE and little capping, thus continued scattered to numerous storms are expected in the SPC Slight Risk region. These storms would present mainly a wind threat as they cross Ohio, and should be beginning a weakening trend as they reach the ZZV area by early to mid- evening as instability begins to diurnally decrease. Still, an isolated risk of damaging wind still exists, particularly if some cold pool conglomeration can occur with storm clusters - overall shear levels are a bit weak to support storm organization. Also of note - an isolated flooding threat cannot be ruled out with PWATs in the 75th to 90th percentile, deep warm cloud depths, and slow storm motion. Convective activity will become more isolated and reach a relative minimum during the early overnight. Some nocturnal scattered development is possible east of Pittsburgh overnight in weak inverted surface troughing, with much of this activity departing after sunrise. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... KEY MESSAGES: - Slightly higher flash flooding threat Sunday; marginal severe risk to the east of Pittsburgh. - Lesser storm/shower chances Monday, mainly in the West Virginia ridges - Sunday/Monday temperatures in the mid to upper 80s ---------------------------------------------------------------- Frontal passage on Sunday still presents a bit better threat of flooding as compared to today with the arrival of the surface cold front. PWATs of 1.6 to 1.7 still represent 90th percentile levels, and the same support for warm rain processes and slow storm motions remain. Given better precipitation coverage with the boundary, the ongoing WPC marginal excessive rainfall risk seems reasonable. The severe risk remains in place as well, particularly to the east of Pittsburgh in the SPC day 2 marginal risk area, with sufficient MLCAPE and DCAPE to continue to support a downburst wind risk. Overall, the flood risk looks to be a bit more concerning than severe potential, but trends will continue to be monitored. Although temperatures remain a bit above normal Sunday, the clouds and precipitation will mitigate the heat risk. After a quiet and still balmy overnight period Sunday night, a shortwave passage on Monday is still forecast. The axis looks to be east of Pittsburgh by the time of peak heating, and may be trending a bit faster. Chances for scattered showers/storms are best in the WV ridges, but at this time, it appears that any isolated severe/flooding threat would lie to the east of our region. A slower timing could pull these threats back west. Temperatures remain above normal with a very modest air mass change behind the Sunday front. && .LONG TERM /TUESDAY THROUGH SATURDAY/... KEY MESSAGES: - Mostly dry and warm Tuesday. - Heat Wednesday, with rain chances increasing late week. ------------------------------------------------------------------- Rain chances decrease into Tuesday with the arrival of surface high pressure and general upper subsidence. Because of this, the region will likely have light to calm winds with a slight decline in dew points with mostly clear skies and mixing into drier air aloft. his should keep conditions pleasant despite general upper ridging and highs above normal. Into Wednesday and Thursday, the high is generally expected to move east off the Atlantic coast, allowing the return of warm and moist southwest flow. This will likely result in Wednesday being the hottest day of the work-week with overnight lows staying elevated Thursday morning in moisture. Heat Risk tops out at "Major" levels with the most recent update. There is still about five degrees of temperature uncertainty Wednesday related to precipitation chances and cloud cover. Depending on the speed of a trough passage and cloud cover trends, temperature spread increases Thursday. Thursday has the potential to be comparable to Wednesday heat, through most ensembles are lower in clouds and the best chances of rain this week as a shortwave skirts south of the main surface front. Wednesday and Thursday also have the highest proportional chances of severe weather and flooding as indicated by machine learning, and CIPS analogs. Rain chances linger through Friday as the probability for the main surface front passage increases, though at this point, there are varying solutions in clustered guidance with some solutions suggesting ridging in the upper Great Lakes which would maintain near 588dm heights and warmth, but some show trough development which might sweep downstream and return temperatures close to normal. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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Ongoing convection across eastern Ohio and the ridges of northeast West Virginia will continue to dissipate over the next few hours as heating wanes. This also goes for the isolated activity that developed in western PA. Kept a mention (via PROB30s) of -SHRA through 03z to reflect this gradual process, followed by a quiet night. Some MVFR ceilings are possible southwest of PIT overnight in low-level moisture and cannot rule out fog as well, particularly at any terminal that receives a storm this afternoon. However, confidence in impacts at any of the area terminals remains too low to warrant a mention in the 00z TAF cycle. A cold front brings more widespread precipitation chances on Sunday. Best coverage likely occurs after 18z, though some isolated morning showers could bring rain (and possibly a few rumbles of thunder) to terminals earlier than that. VFR will prevail outside of showers/storms, with brief restrictions possible in any precipitation. Any stronger storms will also be capable of producing damaging wind gusts and frequent lightning. Outlook... Ensemble models favor high pressure that drastically limits convective potential Monday/Tuesday (but localized morning fog can`t be ruled out). Precipitation and restrictions become more likely on Wednesday and Thursday as southwest flow and moisture increase.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...CL NEAR TERM...CL SHORT TERM...CL LONG TERM...Milcarek AVIATION...Cermak/CL