Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 07 2025 20:01:00 ACUS01 KWNS 072000 SWODY1 SPC AC 071959 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Thu Aug 07 2025 Valid 072000Z - 081200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS.... ....SUMMARY... Scattered severe thunderstorms are expected later today into tonight across the northern Plains. The most likely corridor is centered on North Dakota, where a few tornadoes, very large hail, and a conditional risk for significant severe gusts are possible. ....20z Update Northern Plains... Early afternoon surface and satellite observations show low-level convergence increasing along the intersection of an outflow boundary/composite front and weak lee low over eastern MT. Along and south of the front, strong diurnal heating should gradually destabilize a very moist air mass with dewpoints in the low 70s F. Large to extreme CAPE is expected, owing to steep mid-level lapse rates, though with some capping likely to remain in place with southward extent. Rapid thunderstorm initiation appears probable this afternoon along the low-level convergence zone and in the higher terrain farther west as a shortwave trough proceeding the primary mid-level wave over the Northern Rockies ejects eastward. Initial storm mode is likely to be supercellular along or on the immediate cool side of the surface boundary. This would initially favor a large hail risk (some significant), and the potential for a few tornadoes, should storms become surface based. Tonight, the primary uncertainty continues to be small-scale storm dynamics governing upscale growth and the potential for bowing MCS/rear-inflow jet development. Should this occur relatively early on in the convective evolution (as shown by some CAMs), significant damaging winds (Gusts 80+ mph) are possible across portions of ND/SD through tonight. However, this remains highly uncertain and conditional. Regardless of the initial evolution, significant ascent from the primary upper trough ejecting eastward appears robust enough to support upscale growth with any ongoing convection and additional storms emanating from eastern MT later tonight. This could result in one or more clusters of strong storms capable of damaging gusts, hail and a tornado or two. Given recent trends, have shifted the northern bound of the level 3 Enhanced northward and eastward across ND/MN for significant damaging wind potential. Otherwise, see MCD #1896 and #1897 for short-term information. ...Lyons.. 08/07/2025 ..PREV DISCUSSION... /ISSUED 1114 AM CDT Thu Aug 07 2025/ ....Eastern MT/Dakotas/Western MN... A large upper trough is digging into the Pacific Northwest region today, with several shortwave perturbations tracking from the northern Great Basin into MT/ND. One feature is currently over eastern MT and has been fostering scattered thunderstorms across that region. Convection in this area is currently in a diurnal lull, but may re-invigorate later this afternoon across parts of central ND as daytime heating/destabilization occurs. Backed low-level winds, dewpoints in the 70s, and high CAPE values will promote a favorable environment for a few supercells capable of very large hail, a few tornadoes, and damaging wind gusts. These storms could persist into the evening, tracking into western MN. Another shortwave trough currently over western ID will overspread the mountains of ID/western MT this afternoon, promoting the development of scattered strong storms. This activity should intensify further as it moves into a very moist/unstable airmass across southeast MT, with a consensus of CAM guidance suggesting upscale growth into a bowing complex by early evening. As these storms progress rapidly eastward across ND/northern SD, there remains the potential for a swath of significant wind damage, along with large hail and a tornado or two. Some guidance suggests the MCS will remain severe well into the night, affecting parts of western/central MN. $$ = = = 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) .