FXUS61 KPBZ 202009 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 409 PM EDT Fri Mar 20 2026 .WHAT HAS CHANGED... Severe storm potential has trended down a bit for this afternoon and evening, given the preceding rain hindering heating. Given strong heating and favorable dynamics Sunday, a small uptick in strong storm potential is noted. && .KEY MESSAGES... 1) Low potential for strong to severe storms during the late afternoon and evening, with hail appearing to be the primary threat. 2) Somewhat better storm potential on Sunday, with all severe threats in play. && .DISCUSSION... KEY MESSAGE 1... Severe potential for this afternoon appears to be on the downswing overall. An area of largely stratiform rain is advancing southward into the region ahead of a mid-level shortwave. An associated surface cold front and perhaps some left exit region jet dynamics are supplying the lift, while precipitable water slowly increases in mean low-level southwest flow. This rain should hinder destabilization during the afternoon, and even the thickening clouds ahead of this rain are inhibiting surface heating. CAM guidance supports the notion that healthy convective updrafts will be hard to come by, with HREF mean surface-based CAPE topping out at 300 J/kg or less. That said, the post-frontal environment during the evening could support a low-end risk for hail. While the boundary layer remains stable due to the rain and the setting sun, steepening mid-level lapse rates, approaching the 7-8 C/km range, may support some elevated instability (MUCAPE of around 500 J/kg). Combined with 0-6km shear still between 40 and 50 knots, post- frontal convection suggested by CAMs could have sufficient updraft/downdraft separation for marginally severe hail in the strongest cells. If some sort of surface-based instability can develop, one or two strong to marginally severe wind gusts could be possible. QPF totals through tonight top out in the 0.25 to 0.50 inch range, with the higher totals likely in the ridges as supported by hi-res model data. Of course, locally higher totals could be possible in any heavier storms. Any showers/storms should largely pull south of the region by 06Z with the departing boundary. KEY MESSAGE 2... After a quiet Saturday, a somewhat more robust threat for severe weather is present for Sunday. Warm frontal passage Saturday night, attached to Great Lakes low pressure, allows for southwest flow promoting strong heating during the Sunday daylight hours. Well-above normal high temperatures are forecast, supported by 850mb temperatures approaching 15C. Highs will mainly be in the 70s, perhaps near 80 in the vicinity of the Mason-Dixon Line. MUCAPE levels of at least 500-1000 J/kg are suggested by ensembles Sunday afternoon, with a lot of that in the ideal hail growth zone. 0-6km shear may top out in the range of 50-60 knots. As another cold front drops across the region during the afternoon and evening, some supercell structures may be supported in this environment, with all severe hazards on the table. At present, parameters appear best aligned in eastern Ohio. This is where SPC has placed a Slight (level 2 of 5) severe risk, with a Marginal (level 1 of 5) in much of the rest of the CWA away from the ridges. Weakening convection would accompany the front through the night, with dry weather and cooler temperatures returning for Monday. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... Southwesterly wind gusts persist today ahead of a surface cold frontal passage. Rain has already began aloft, which will progressively filter its way to the surface at ports over the next couple hours. Through 00Z, showers will be hit or miss, and while thunder couldn't be completely ruled out, its generally less than 20% likely at any given port. Along/behind the front itself, the environment may be a bit more unstable, but there is a low probability of convective development, therefore, maintained PROB30 groups at any ports where an isolated thunderstorm is most possible after sunset. Into tonight, recent rains and saturation in wake of the front will allow the chance of widespread MVFR cigs, with a chance of IFR at DUJ/FKL. Dry air advection in wake of the front will progressively improve cigs into the morning hours Saturday. Widespread return to VFR are likely by 16Z. Outlook... VFR cigs return late morning Saturday. A frontal passage Sunday could return strong thunderstorms to the region during the afternoon. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ DISCUSSION...CL AVIATION...Milcarek