534 FXUS61 KPBZ 050706 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 306 AM EDT Thu Jun 5 2025 .SYNOPSIS... Shower and thunderstorm chances return today with an approaching cold front. This front will drift across the region through Sunday, as waves of low pressure track along it. This will result in periodic shower and thunderstorm chances through the weekend. && .NEAR TERM /THROUGH TODAY/... KEY MESSAGES: - Shower and thunderstorm chances increase today - Marginal Risk for mainly damaging wind gusts - Locally heavy rain possible --------------------------------------------------------------- Mid and high level clouds will continue to increase this morning ahead of an approaching cold front, which was located from wrn NY to southern Lake Erie to NW Ohio early this morning. With the flow aloft nearly parallel to the front, the southeastward progression will be slow. An upper level shortwave will also approach the region today in the SW flow aloft, crossing the Upper Ohio Valley region this afternoon/early evening. This should help drive the front further SEWD this afternoon, with showers and thunderstorm increasing. HREF mean MU CAPE shows 1000-1500 j/kg this afternoon as the front approaches. Shear should be relatively weak (20kt 0-6km), though some dry air in the mid levels could result in a damaging wind gust potential this afternoon into early evening. DCAPE levels are expected to range from 600-850 j/kg, as downdrafts experience evaporative cooling in the dry layer, and accelerate toward the surface. Some hail will also be possible, but the main hazard is expected to be damaging wind gusts. The Storm Prediction Center has much of the area highlighted in a Marginal Risk (or level 1 out of 5) for severe storms this afternoon and early evening. With the slower storm motion expected, and PWATS around 1.5, any training or repeated showers/storms over the same location could result in localized flooding. Will continue to include the severe and flood potential in the Hazardous Weather Outlook. Another warm day in the 80s is expected before the shower/storms increase later today. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... KEY MESSAGES: - Showers and thunderstorms continue at times - Marginal Risk for damaging thunderstorm wind gusts Friday - Locally heavy rainfall possible through Friday night ---------------------------------------------------------------- The front is expected to stall across the Upper Ohio Valley region tonight. Ongoing showers and thunderstorms should quickly lose intensity during the early evening, with the severe thunderstorm threat ending. Elevated instability is progged to remain overnight, with scattered showers and isolated thunderstorms still possible. The quasi stationary front will remain across the area on Friday, under westerly flow aloft. With building diurnal instability, expect an increase in coverage of showers and thunderstorms again through the day. Increasing flow aloft and MU CAPE from 1000-1500 j/kg could result in a marginal potential for damaging wind gusts again Friday afternoon and early evening (as highlighted in the SPC day 2 outlook.) A locally heavy rainfall potential will also continue with the quasi stationary front across the area. Will continue to highlight this and the severe storm potential in the Hazardous Weather Outlook. Models indicate a vort max in broad upper troughing will track across the region Friday night into early Saturday. This should result in another round of showers and thunderstorms crossing the region, with a locally heavy rain potential. This wave should drive the front further south later on Saturday, with some decrease in rain chances especially north of PIT. Another shortwave and surface low are expected to develop and track east along the front Saturday night, returning the front northward as a warm front. This should maintain a chance of showers across the region overnight. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... KEY MESSAGES: - Unsettled weather Sunday through Tuesday - Dry Wednesday ------------------------------------------------------------------- Models have trended toward a stronger shortwave trough crossing the Upper Ohio Valley region on Sunday, as a surface low tracks along the quasi stationary front to our south. The GFS is an outlier, developing a stronger surface low and pulling the front back farther northward than most other guidance. Stayed close to the ensemble solution, resulting in increasing shower and thunderstorm chances through the day with the passing wave. Another trough is progged to tack from the Upper Midwest to the Great Lakes and Upper Ohio Valley region Monday and Tuesday. Shower and thunderstorm chances will again increase with the approach and passage of the trough. Dry weather is expected to return on Wednesday as the trough exits, and surface high pressure builds in. Temperatures are expected to average near seasonable levels through the period. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... General VFR conditions are expected through the TAF period, with the exception of localized restrictions with afternoon/evening convection. Mid/upper level clouds will increase through the morning hours. Isolated to scattered showers and thunderstorms are expected Thursday afternoon, roughly developing near ZZV-BVI-FKL by around 18z and exiting the area shortly after 00z. Latest guidance leans towards lower coverage than previously anticipated, and quickly-dissipating storms as they cross western PA. There is low confidence on the continuation of showers after 00z. Generally have kept prevailing SHRA where confidence in showers/storms is highest, and Prob30s covering the most likely window of potential thunderstorms at each terminal. Showers and storms look to remain fairly high-based, so any restrictions will likely be limited to brief visibility reductions. Fog may develop into the overnight near terminals that do see rainfall. Outlook... Widespread MVFR/IFR ceiling restrictions are expected Friday as a series of shortwaves brings continued shower and thunderstorm chances Friday and Saturday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...WM NEAR TERM...WM SHORT TERM...WM LONG TERM...WM AVIATION...Rackley