Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 08 2025 19:42:35 ACUS01 KWNS 081942 SWODY1 SPC AC 081941 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0241 PM CDT Fri Aug 08 2025 Valid 082000Z - 091200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT FOR PARTS OF THE UPPER MIDWEST AND THE CENTRAL HIGH PLAINS... ....SUMMARY... Scattered severe thunderstorms with damaging winds, large hail, and a couple tornadoes are possible this evening and tonight across parts of the Upper Midwest and the central High Plains. ....20z Update... ....Upper Midwest... Latest radar/satellite trends show a residual storm complex and cloud cover over northeast Minnesota. This activity continues to diminish, with some weak convection developing in proximity. Surface observations suggest little evidence of extensive outflow in its wake, though southeasterly surface winds are prevalent across much of Minnesota where cloud cover has remained persistent. To the west, a cold front continues to advance eastward and is beginning to impinge upon portions of northwest Minnesota into eastern South Dakota. Storm initiation is still expected by early evening along the cold front in eastern South/North Dakota, with a quick transition from cellular to linear modes. Not much has changed in terms of expectations from the prior outlook. As this activity grows upscale and matures, some potential for a more concentrated corridor of damaging winds may emerge in far northeast Minnesota, but details remain uncertain and will be reevaluated in the 01z Outlook. With that said, given the potential for upscale growth, have expanded the Marginal area (Level 1 of 5) eastward into portions of northeast Iowa and vicinity. ....Southwest South Dakota/Nebraska Panhandle... Surface observations and SPC mesoanalysis show a post-frontal airmass with enough residual moisture to allow for modest destabilization across the region. Recent CAM guidance suggests the potential for isolated convection to develop in the high terrain of eastern Wyoming and persist eastward into southwest South Dakota and the Nebraska Panhandle. Given effective shear of 45-50 kt in association with enhanced flow along the southern periphery of the upper-level trough, a few supercell storms are possible with severe hail/wind the main threats. Therefore, have introduced a Slight Risk (Level 2 of 5) to encompass this potential. ...Karstens/Lyons.. 08/08/2025 ..PREV DISCUSSION... /ISSUED 1118 AM CDT Fri Aug 08 2025/ ....Upper Midwest... The large convective complex that affected ND/MN last night has mostly dissipated, with the associated shortwave trough lifting across the MN Arrowhead. Shortwave ridging is occurring in the wake of this system, which should suppress deep convective development for most of the afternoon. Southeasterly low-level winds and daytime heating across much of MN and eastern SD will help re-establish a very moist/unstable air mass (MLCAPE > 4000 J/kg) by late afternoon. Another strong shortwave trough now over WY will begin affecting the ND/MN area by that time, with an associated cold front approaching the area. Scattered thunderstorms are expected to form along/ahead of the front, mainly after 00z. Deep-layer shear will support supercell storm structures capable of large hail and damaging wind gusts. A few tornadoes are also possible, given the very moist environment and backed low-level winds. However, many of the storms may be elevated and behind the front. Activity will persist deep into the night, spreading eastward across MN and into parts of northern WI and western Upper MI. $$ = = = 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) .