


Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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528 FXUS61 KPBZ 301753 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 153 PM EDT Mon Jun 30 2025 .SYNOPSIS... Scattered showers and thunderstorms expected this afternoon and again on Tuesday. A few storms could produce damaging winds and localized flooding. Dry weather with slightly above normal temperatures returns through Saturday save a chance of showers and storms on Thursday. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Scattered strong to severe thunderstorms with heavy rain possible this afternoon and evening. - Muggy overnight with some areas of fog possible. --------------------------------------------------------------- A stalled boundary will lift north as a warm front today with increasing showers and thunderstorms in the warm sector aided by a passing mid-level shortwave. The environment will look a bit different today than the past several days with bit more shear be available with marginally increasing low and mid level flow, especially north of Pittsburgh. The morning showers and scattered cloud cover may mute the environment some for a severe threat farther north, but the 12z HREF still suggests a 60-70% chance of SBCAPE >1000 J/kg and 30 knots of deep layer shear by this afternoon. Equilibrium levels are high with a deeper CAPE profile, so wouldn`t be surprised to see better updraft cores today. This environment supports the chance for more organization in convective development potentially into broken line segments capable of damaging wind and marginally severe hail, though think the hail threat is lower given the saturated profile not supporting hail maintenance. There will also be a low, but not zero, tornado threat confined to around the US-422 to I-80 corridor in closest proximity to the surface boundary. Increasing south/southwest 925-850 mb flow atop south/southeasterly surface flow will elongate the lower part of the hodographs suggesting a bit higher potential for streamwise vorticity ingestion in favorably south/southeasterly right movers. STP there nudges up to 0.3-0.7. The other threat will be heavy rainfall with deep layer southerly flow pumping in PWAT values nearing 2 inches. What might help us mitigate a significant excessive rainfall threat is upwind propagation vectors in the 15-20 knot range rather than <10 knots and a deeper CAPE profile suggesting warm rain processes might not be as dominant as previous days. Still, with those PWATs, HREF probability for >1"/hour rates is as high as 50% in northwest PA, specifically Lawrence, Mercer, and Venango Counties, as well as in the PA ridges. So, have opted to go with a flood watch through 10pm tonight to cover this threat especially given our relatively hydrophobic conditions with recent rainfall. Convective activity likely wanes after sunset and gives way to a warm and humid overnight period with lows 8-10 degrees above normal. Some fog is possible in sheltered areas and valleys that see rain today, but elevated wind likely precludes most development. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Showers and thunderstorms with another risk for severe and heavy rainfall Tuesday. - Temperatures climb a bit with drier weather on Wednesday. ---------------------------------------------------------------- Another round of showers and storms will develop on Tuesday along and ahead of a passing cold front and mid level trough. Some uncertainty arises with potential morning convection along a pre- frontal trough, especially in northern WV and southwest PA. Not all CAMs have this, but if it does develop, it could taint the local environment ahead of the afternoon FROPA. What else it could do is enhance the flooding threat in the same area with several rounds of showers and storms in a still tropical-like environment with near 2" PWATs. Faster storm motion should again preclude more notable flood threats, but the environment will support heavy rainfall. With the frontal passage, HREF prob for 1000 J/kg SBCAPE and 30 knots of deep layer shear reaches 70-80%, so again a favorable environment to support organization and a damaging wind threat. Highest probability for severe at this point looks to be north of Pittsburgh, but with morning uncertainty that threat could shift farther south. SPC has maintained the expanded Marginal Risk (1/5) as far back as DUJ to PIT to HLG. A dry day comes Wednesday in the wake of the front with surface high pressure nosing in from the west. Dew points come down back into the low to mid 60s but temperatures are still likely to breach 85F for highs with up to an 80% chance in southeast Ohio and the southwest PA urban areas. && .LONG TERM /THURSDAY THROUGH SUNDAY/... KEY MESSAGES: - Cold front Thursday brings back showers and storms. - July 4th holiday looks dry. - Rain chances return late next weekend. ------------------------------------------------------------------- A shortwave will churn through the ECONUS longwave trough on Thursday and kick a cold front through the area from the northwest. Timing remains a bit uncertain, but passage is likely some time late morning to mid-afternoon which will return the chance for showers and storms. It remains unclear how much effect the high and associated lingering subsidence may have as the front butts up against it. Dew points ahead of it look to sit in the low 60s with not much return flow on Wednesday, but the NBM prob for >1000 J/kg SBCAPE is around 50-60% in the afternoon hours. Deep layer shear may be the lacking component with the best forcing and flow displaced to the north with the shortwave. Still, machine learning does peg at least a low-end chance of severe weather with the passage, contingent on it being at a favorable diurnal time. Headed into the fourth, ensembles are in good agreement on a return of mid-level ridging behind the departing longwave. Some subtle timing differences arise with how quickly the ridge builds which suggests that high temperatures are lower confidence right now, but some of the MaxT spread has decreased with a trend toward a warmer solution in the mid to upper 80s. Rain chances are low in any scenario at less than 20% with dry air advecting in in the wake of Thursday`s boundary. The ridge flattens out into the weekend with a mid-level zonal flow pattern taking over. Ensembles do agree on low pressure development across the Northern Plains sometime Friday into Saturday and quickly sliding east, but disagreement on timing lends low confidence precipitation chances locally as the attendant surface cold front follows along with it. Most of Saturday looks dry at this time with even the faster solutions holding precip chances off until early Sunday, so most likely will see a more unsettled pattern return for the latter half of the weekend and into next week. Temperatures around average through the second half of the week may warm to slightly above average for the weekend. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... Several rounds of showers and thunderstorms are expected through this evening in a very moist airmass behind a warm front. A shortwave currently crossing Ohio will likely provide the most focused threat for thunderstorms containing heavy rainfall/IFR visibility and wind gusts. Used 3-4 hour TEMPO groups for most terminals to illustrate most likely timing, based on the shortwave passage mainly, but recognizing that at least a few may get hit more than once with thunderstorms. Wind gusts could reach as high as 25-30 knots with any storm. Convection should gradually wane this evening with the loss of diurnal instability, and as the shortwave exits. Left VCSH mention at most sites for now into the overnight hours due to uncertainty regarding precip end times. Lingering low-level moisture will lead to an MVFR/IFR stratus deck overnight, with enough mixing remaining to keep widespread fog from developing. Slow improvement is expected after sunrise. Cannot rule out a shower or storm prior to 18Z, but left out for now due to low probability. Outlook... A crossing cold front will result in numerous showers and thunderstorms again on Tuesday afternoon and evening. VFR returns Wednesday under high pressure, before restriction and thunderstorm potential returns with a Thursday cold front. VFR is expected again by Friday under high pressure. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Flood Watch until 10 PM EDT this evening for PAZ007>009- 013>016-020>022-073>078. OH...None. WV...None. && $$ SYNOPSIS...MLB NEAR TERM...MLB SHORT TERM...MLB LONG TERM...Rackley/MLB AVIATION...CL/WM