Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 14 2025 19:59:54 ACUS01 KWNS 141959 SWODY1 SPC AC 141957 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Thu Aug 14 2025 Valid 142000Z - 151200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN NORTH DAKOTA...NORTHWEST MINNESOTA...AND FAR NORTHEAST SOUTH DAKOTA... ....SUMMARY... Thunderstorms capable of producing large hail and severe wind gusts may occur this afternoon into tonight across parts of the northern/central Plains and upper Mississippi Valley. Isolated strong to severe gusts are also possible from the eastern Great Basin into the central Rockies. ....20Z Update... The forecast remains on track, and only minor changes were made with this update. Isolated to widely scattered thunderstorms are still expected along the cold front as it impinges on a destabilizing air mass across the northern Plains/Upper MS Valley tonight. Large hail and locally severe gusts will be possible with any organized clusters/supercells that evolve. Elsewhere, see MCDs 1944 and 1945 for details on the near-term severe risks in the Great Basin/central Rockies and Upper Midwest. ...Weinman.. 08/14/2025 ..PREV DISCUSSION... /ISSUED 1129 AM CDT Thu Aug 14 2025/ ....Northern Plains into the Upper MS Valley... Recent surface analysis places a low over northwest ND, along a cold front arcing from west-central Manitoba into south-central MT. A surface trough also extends southward from this low to another weak low in southeast CO. Ample low-level moisture exists across the Plains east of this surface troughing, with mid 60s dewpoints extending up through central and eastern ND. Moist southerly low-level flow is forecast to persist throughout the day. This low-level moisture advection combined with evapotranspiration and low-level convergence near the front is expected to result in upper 60s to perhaps low 70s dewpoints ahead of the front across the eastern Dakotas by early evening. Cooling mid-level temperatures are expected across the region, which will combine with the abundant low-level moisture to support strong to very strong buoyancy by the late afternoon/early evening. Recent guidance suggests MLCAPE will range from 3000 to 4000 J/kg across the eastern Dakotas, western MN, and central/eastern NE by 00Z Friday. Despite this robust buoyancy, warm low to mid-level temperatures and related capping introduce uncertainty regarding convective initiation, particularly with southward extent. Greatest potential for convective initiation remains across eastern ND where glancing large-scale ascent attendant to the substantial shortwave trough moving through Saskatchewan will augment low-level convergence along the southeastward-progressing cold front. Any convection which can be sustained could pose a threat for large to isolated very large hail given a favorable thermodynamic and kinematic environment. Given the warm and dry low to mid-levels, strong downdrafts are possible as well. Upscale growth into clusters along the front is possible, and some damaging gusts could occur with these storms as well. Inhibition will quickly increase with eastward extent across MN as nocturnal cooling of the boundary layer occurs, limiting the eastward extent of the severe threat. Additionally, the low-level jet will likely weaken throughout the day but then strengthen again later this evening from western KS into western IA. Associated warm-air advection could result in isolated elevated convection across central MN. Most of these storms should be sub-severe, but a few instances of hail are possible. ....Central High Plains/Central Plains... Scattered high-based thunderstorms should develop across the central Rockies this afternoon before the spreading eastward/southeastward into the central High Plains. A deeply mixed boundary layer and high cloud bases will support strong gusts with this activity as it moves across central High Plains. As this convection spreads eastward and encounters greater instability along/east of a surface lee trough, it may reintensify, with the potential for severe gusts continuing into central NE. The lack of stronger forcing aloft and modest deep-layer shear should temper the overall severe threat with southward extent. ....Eastern Great Basin into central Rockies... The shortwave trough currently moving into central CA will continue eastward/southeastward throughout the day. Lift associated with this wave will interact with the modest mid-level moisture across the Great Basin to support scattered thunderstorm development. High cloud bases and a deeply mixed boundary layer could support strong downdrafts within the strongest storms, particularly across northern UT where the best overlap between forcing, buoyancy, and modest southwesterly flow aloft exists. $$ = = = 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) .