Mesoscale Discussion 1733 NWS Storm Prediction Center Norman OK 0927 PM CDT Mon Jul 29 2024 Areas affected...parts of southern Illinois...adjacent portions of Indiana and Kentucky Concerning...Severe Thunderstorm Watch 563... Valid 300227Z - 300430Z The severe weather threat for Severe Thunderstorm Watch 563 continues. SUMMARY...Ongoing thunderstorms may gradually evolve into organizing southeastward propagating cluster with increasing risk for potentially damaging wind gusts through 11 PM-Midnight CDT. DISCUSSION...Storms initiating to the northeast through east of the Greater St. Louis area, have been supported by forcing for ascent associated with low-level warm advection, in the wake of mid-level troughing slowly digging through the upper Great Lakes/Ohio Valley. This has been occurring within a very moist (including upper 70s surface dew points) and highly buoyant boundary layer, in the presence of at least modest clockwise curved hodographs, beneath 30-40+ kt northwesterly flow in the 700-500 mb layer. While a few supercell structures have evolved, with gradual decoupling of the boundary layer underway and flow closer to the surface (near and below 850 mb) forecast to remain more modest, tornadic potential seems likely to remain limited. However, with some further upscale growth still probable through 04-05Z, increasing outflow, aided by evaporative cooling within dry/potentially cool air in the lower/mid-troposphere and melting hail, may be accompanied by increasing potential for damaging surface gusts. ..Kerr.. 07/30/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IND...PAH...ILX...LSX... LAT...LON 38448874 38668808 38498750 37888723 37578843 38078912 38548949 38448874
Storm Prediction Center Mesoscale Discussion 1733

29
Jul