Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Aug 16 2025 01:00:58 ACUS01 KWNS 160100 SWODY1 SPC AC 160059 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Fri Aug 15 2025 Valid 160100Z - 161200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO THE OVERNIGHT HOURS ACROSS PARTS OF CENTRAL AND EASTERN SOUTH DAKOTA...NORTHERN NEBRASKA...SOUTHWESTERN MINNESOTA...NORTHWESTERN IOWA...PARTS OF SOUTHEASTERN IOWA AND SOUTHWESTERN WISCONSIN... ....SUMMARY... An organizing cluster of thunderstorms with potential to produce strong to severe wind gusts may still evolve later this evening into the overnight hours across parts of the middle Missouri Valley and adjacent Great Plains. ....01Z Update... Stronger westerlies remain generally confined to the higher latitudes, near/north of the Canadian/U.S. border. To the southwest of one significant embedded short wave trough crossing the Hudson Bay and northern Ontario vicinity, modest westerly mid-level flow (including speeds of 30-40 kt around 500 mb) is overspreading areas as far south as the Dakotas into Upper Midwest, near the northern periphery of mid-level ridging. Forcing associated with subtle perturbations embedded within this regime has contributed to several developing clusters of storms. A couple now propagating east of the upper Mississippi Valley appear to be in the process of weakening, likely due to some combination of weak/weakening lift and increasing inhibition beneath relatively warm mid-level temperatures encompassing much of the northern and central Great Plains into Midwest. Beneath steeper mid-level lapse rates upstream, boundary-layer moisture east of the lee surface trough across the high plains is still contributing to strong to extreme potential instability across much of central and eastern South Dakota/Nebraska, as scattered high based convection emerges from eastern Wyoming and northeastern Colorado. It appears possible that low-level forcing for ascent, near the nose of a nocturnally strengthening southerly low-level jet, could contribute to a consolidating and upscale growing cluster, particularly as activity acquires more unstable inflow later this evening into the overnight. Various model output, including the NAM and Rapid Refresh, suggest that the evolution of a notable convective perturbation is possible, which could be accompanied by a swath of strong to severe wind gusts. ...Kerr.. 08/16/2025 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .