Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 20 2025 07:32:01 ACUS03 KWNS 200731 SWODY3 SPC AC 200730 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Fri Jun 20 2025 Valid 221200Z - 231200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL NE INTO NORTHWEST IA...THE EASTERN DAKOTAS...AND WESTERN/CENTRAL MN... ....SUMMARY... Severe thunderstorms may develop on Sunday from parts of the central and northern Plains into the upper Midwest. ....Synopsis... A mid/upper-level shortwave trough and attendant jet maximum are forecast to move from the central Rockies towards the northern Great Plains on Sunday. A surface low will move from NE/SD northeast toward Lake Superior, as a trailing cold front moves through parts of the northern/central Plains. Downstream, an upper ridge will amplify further across the eastern CONUS through the day, as a shortwave trough initially over New England moves offshore. ....Great Plains into the Upper Midwest... Strong to extreme instability is again forecast to develop along/ahead of the cold front across parts of the central/northern Plains into the Upper Midwest. Guidance generally suggests that stronger ascent and deep-layer flow associated with the ejecting mid/upper-level shortwave trough may lag behind the front, resulting in some uncertainty regarding the magnitude and coverage of the severe threat. However, strong diurnal heating will support potential for storm development in the vicinity of the front, and also southward along a surface trough into the central and perhaps southern High Plains. Given the magnitude of instability, deep-layer shear will be sufficient for some storm organization, with a few strong cells or clusters possible. A Slight Risk has been added from central NE into MN, where confidence is currently greatest in development of widely scattered strong to severe storms during the afternoon and evening. Convection may persist into late Sunday night, with an isolated severe threat spreading gradually eastward. Isolated severe storms will also be possible within the post-frontal regime across the central/northern High Plains, though guidance varies regarding the magnitude of MUCAPE in this region. High-based storms may develop into parts of the southern High Plains, with a threat of isolated strong to severe gusts. ....Parts of the Northeast/New England... Guidance varies substantially regarding the strength/timing of the shortwave trough and related flow fields that will move across New England Sunday morning. Depending on the strength of the system and the evolution of convection on D2/Saturday, there is some potential for isolated strong to severe storms Sunday across the region, given the presence of increasing buoyancy and favorable deep-layer shear. A slower system could result in a more robust diurnal threat, while a faster system may confine the primary threat to the morning. ...Dean.. 06/20/2025 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .