Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 07 2025 06:10:57 ACUS02 KWNS 070610 SWODY2 SPC AC 070609 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0109 AM CDT Thu Aug 07 2025 Valid 081200Z - 091200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ....SUMMARY... Scattered severe thunderstorms are expected Friday afternoon and evening across parts of the northern Plains and upper Mississippi Valley. ....Northern Plains/Upper Mississippi Valley... A negatively tilted mid-level trough and an associated 50 to 60 knot jet streak will move through the northern Plains on Friday. At the surface, a cold front will advance eastward across the Dakotas, as convection early in the day moves through the upper Mississippi Valley. Ahead of the front, a moist and strongly unstable airmass will be in place, with surface dewpoints from the upper 60s to the mid 70s F. Low-level convergence will increase ahead of the front in the afternoon, helping to support scattered thunderstorm development. A cluster of strong to severe storms appears likely across parts of the northern Plains Friday afternoon and evening. A pristine thermodynamic environment is forecast to develop across the northern Plains Friday afternoon. NAM forecast soundings in the late afternoon along the instability axis near Fargo, North Dakota have MLCAPE near 5,500 J/kg with 700-500 mb lapse rates approaching 8.5 C/km. Along the axis of instability, 0-6 km shear is forecast to be in the 35 to 45 knot range, which should be favorable for supercells with large hail. Hailstones of greater than 2 inches in diameter will be possible within the stronger cores. Severe wind gusts will also be possible. There is some concern that convection along or ahead of the front will remain to the west of the strongest instability. Although the models vary concerning this scenario, the latest ECMWF has trended toward an earlier convective initiation. The ECMWF solution, which also develops convection further to the south, would be more favorable for a significant severe weather event across the northern Plains Friday afternoon and evening. ....Western Dakotas... A post-frontal airmass will be in place across the western Dakotas on Friday, as a cold front advances eastward away from the region. Warming surface temperatures will contribute to weak instability by afternoon, with MLCAPE approaching 1000 J/kg in some areas. Large-scale ascent associated with a mid-level shortwave trough should aid the development of a few thunderstorms during the late afternoon and early evening. Moderate deep-layer shear and steep mid-level lapse rates could be enough for a localized severe threat, with hail and isolated severe wind gusts possible. ...Broyles.. 08/07/2025 $$ = = = 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) .