Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 27 2025 20:04:09 ACUS01 KWNS 272002 SWODY1 SPC AC 272000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Sun Jul 27 2025 Valid 272000Z - 281200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN/CENTRAL MINNESOTA AND FAR EASTERN SOUTH DAKOTA... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID-ATLANTIC STATES... ....SUMMARY... Severe thunderstorms are expected this afternoon and evening across parts of the Upper Midwest to western Great Lakes. Other severe storms are also possible in parts of the northern Plains, central Appalachians, and Mid-Atlantic. ....20Z Update... Both the Slight and Enhanced risks were expanded slightly west-southwestward in eastern SD with this update. Here, the latest guidance has come into relatively good agreement, depicting convective development ahead of a gradually evolving surface low into this evening. Very steep deep-layer lapse rates/extreme surface-based buoyancy and 40-50 kt of effective shear will promote supercells/organized clusters capable of producing large hail and severe wind gusts. Farther east, the Marginal risk was expanded southward across southeastern NC into northern SC. Strong heating/destabilization will promote damaging wind gusts with any small thunderstorm clusters that evolve. ...Weinman.. 07/27/2025 ..PREV DISCUSSION... /ISSUED 1200 PM CDT Sun Jul 27 2025/ ....Upper Midwest/western Great Lakes including MN/eastern SD... A convectively enhanced mid-level shortwave trough over northern/eastern North Dakota will continue generally eastward toward northern Minnesota, with a modest flattening of the downstream upper-level ridge into tonight. A modest deepening of the surface low will occur across eastern South Dakota toward the southwest Minnesota border vicinity, with intense thunderstorm development later today generally expected to focus along the southeastward-advancing front, although differential heating and a convectively aided cluster/possible MCV across northeast South Dakota at midday may also be factors. Given the strong buoyancy near/south of the front, and very steep lapse rates/elevated mixed layer impinging from the west-southwest, modestly strong wind profiles will be sufficient for intense supercell development with initial storms, including large hail potential (higher magnitudes possible especially eastern South Dakotas and southwest Minnesota) and some tornado risk. Multiple southeastward-moving clusters should evolve this evening with an increasing likelihood of damaging wind across southern Minnesota into western/northern Wisconsin. Portions of the region have been upgraded to an Enhanced Risk. ....Mid-Atlantic/Central Appalachians... Scattered afternoon thunderstorms will continue to increase regionally. Similar to previous days, mid-level lapse rates will be weak and considerable mid-level moisture will keep the overall potential somewhat limited/isolated. However, the strongest cells will be capable of occasional gusty/damaging winds, with a somewhat higher probability of wind damage seemingly existing across eastern Virginia where buoyancy will be greater. ....Montana... Strong heating will occur this afternoon across much of central/eastern Montana, where deep boundary-layer mixing will lead to inverted-v profiles. Scattered thunderstorms are forecast to develop along a corridor from southwest into central Montana by late afternoon. These high-based storms may pose a risk of a few severe-caliber wind gusts. $$ = = = 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) .