


Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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802 FXUS61 KPBZ 151754 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 154 PM EDT Tue Jul 15 2025 .SYNOPSIS... Mostly dry today save south the WV ridges with heat risk increasing. Daily severe and flood risk continue through at least Friday, with a cooldown to near normal temperatures for the weekend. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Chance of afternoon storms in mostly WV high terrain; marginal risk of excessive rainfall for WV high terrain. - Heat risk increases to moderate (with patchy major) today. --------------------------------------------------------------- A weak trough of low pressure exists on the leeward side of the Appalachians, with both surface and satellite imagery showing southeast flow for the day today. In areas north of the surface front (including Pittsburgh), rain and storm chances remain very low today with PWATS likely hitting a early week minimum of 1.4" on the 12Z sounding. A strong cap aloft with plentiful dry air above should limit convective development north of I-70. Elsewhere, in southeast flow, some high moisture from south of the boundary will come streaming into the West Virginia ridges, with some lift enhanced by orographics. The 12Z Sterling, VA sounding showed this high moisture with PWATS of ~1.8" This will lead to a chance of storm development. With minimal dry air in the lowest 500mb on the sterling sounding, outflows and severe potential looks generally unlikely, but this may also mean that storms cold stall, tied to the high terrain ridge-top convergence in the WV mountains. Conditional on storm development and training, HREF maxima suggest the potential for 3" to 5" exists on a very localized bases, but this still remains low probability. Into the overnight hours, chances of rain drop off with loss of heating and dews in the upper 60s to low 70s will inhibit much cooling, keeping lows above normal and allowing patchy fog. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... KEY MESSAGES: - Wednesday and Thursday will feature an afternoon/evening chance of rain, heat, severe, and flooding, with flash flooding being the primary risk. ---------------------------------------------------------------- Any patchy fog will readily erode in the morning with mixing. Through the day, a shortwave will cross the area, veering wind profiles aloft and enhancing lift in the low levels. This will translate to more warm, moist advection in the low-levels with PWATS pushing back close to the 1.9" or 2" mark (between the 90th percentile and maximums). This southwest flow will also all the northeastward push of the aforementioned front back across the area as a warm front, allowing an additional defined forcing axis. This push in higher moisture air will also allow an increase in the flow fields, with mean storm motions up to 15kts to 25kts. With all the moisture in the profiles, severe chances appear quite low unless the drier air aloft is slower to retreat or we get deep morning convection (low probability). No dry air will be favorable for flash flooding, however, with cold pools unable to undercut showers and storms. Warm rain processes in the lowest levels, long skinny CAPE (>95% chance of non-zero MLCAPE), and potential for training, flash flooding risks maximize tomorrow in the afternoon/evening hours. HREF maxima tend to indicate as much as localized 3" to 5" of rain is possible in eastern Ohio, with 2" to 4" of rain possible in PA and WV. After a decrease in convection, patchy fog in high moisture overnight Thursday night, and lows above average yet again, another active day is possible Thursday. Behind the shortwave and the frontal passage, the area will be throughly warm sectored Thursday with a bit more low-flow in wave of the shortwave passage. This might slightly increase the chances of severe, though PWATS appear to remain quite high near the 1.9" to 2.0" PWAT range. Moisture be toward the lower end of the distribution would be needed to realize any downburst wind threats, otherwise, flash flooding remains the primary risk. Warm overnight lows are expected again overnight with a decrease in convective coverage. A weak cold front may enter the northern fringes of the area overnight, cooling temperatures for some along the I-80 corridor. && .LONG TERM /FRIDAY THROUGH MONDAY/... KEY MESSAGES: - More seasonable conditions are likely Friday with precipitation chances mainly south of I-70. - Any reprieve from storm potential is short-lived as active weather pattern likely resumes late Saturday into next week. ------------------------------------------------------------------- The stalled surface cold front is likely to continue its progression south through the morning. It`s expected to be positioned south of Pittsburgh for most of the day Friday. For areas north of the boundary, modest dry, cool advection and high pressure will support dry weather and temperature close to or even below seasonable average. For areas near to south of the boundary, residual moisture and jet aided ascent is likely to foster scattered afternoon thunderstorms; lowering PWATs and weak shear should limit flood potential but keep the threat non- zero. Ensemble models favor a transient area of high pressure north of the area to slide toward New England Saturday but provide enough influence to promote mostly dry weather (though the linger stalled boundary south of the area could spawn isolated afternoon storms). This front will meander north and south somewhere in the periphery of the area for most of the weekend, dipping south and north on shortwave troughs/ridges. This "front meandering" will continue to allow non- zero" rain, severe, and and flooding chances through the weekend and early next week though CIPS and ML keep chances respectively lower. By the middle of next week, there is a bi-modal solution of either developing weak eastern troughing or continued ridging. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... The CU rule and model soundings indicate a scattered (to locally broken) diurnal cumulus layer will continue through late this afternoon. Capping warmth aloft should confine any chance for thunderstorms the WV and PA ridges, where a slightly weaker cap is in place. Expect VFR tonight with increasing high clouds ahead of an approaching shortwave and surface warm front. This wave and warm front will result in scattered showers by morning, with more numerous showers and thunderstorm by the afternoon with building diurnal instability. Included a tempo for thunderstorms in the extended portion of the PIT taf, with thunder likely starting after the end of the forecast period in the remaining sites. Outlook... Numerous showers and thunderstorms are to continue into Wednesday evening as the warm front lifts back north across the region. Daily shower and thunderstorm chances are then expected to continue, especially in the afternoons/evenings, as the front becomes quasi-stationary and drifts across the region. Fog and stratus is also possible each morning, especially where rain fell the previous day. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Milcarek NEAR TERM...Milcarek SHORT TERM...Milcarek LONG TERM...Frazier/Milcarek AVIATION...WM