Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Sep 05 2023 19:54:55 ACUS01 KWNS 051954 SWODY1 SPC AC 051953 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Tue Sep 05 2023 Valid 052000Z - 061200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY/WESTERN UPPER GREAT LAKES REGION...AND FROM MISSOURI AND VICINITY SOUTHWESTWARD INTO NORTHEASTERN OKLAHOMA... ....SUMMARY... Severe thunderstorms are expected this afternoon and evening over parts of the upper Mississippi Valley/Lake Superior region, and across the Ozarks and parts of Oklahoma. Severe wind gusts and isolated large hail are possible. ....Discussion... Along with minor line tweaks in a few areas, including some eastward expansion of thunder into parts of Wyoming for the overnight period, the only other substantive change at this time is the northward expansion of SLGT risk/15% wind into parts of northern Missouri. Here, a similar thermodynamic pre-frontal environment is indicated as compared to areas a bit farther south, and several CAM runs are indicating development along the front may extend a bit farther north than previously hinted at in the outlook. Otherwise, expectations remain similar to those in prior outlooks. ...Goss.. 09/05/2023 ..PREV DISCUSSION... /ISSUED 1131 AM CDT Tue Sep 05 2023/ ....Upper Mississippi Valley... A shortwave trough over the Dakotas this morning will continue eastward toward the upper Mississippi Valley through tonight. A slight cooling of mid-level temperatures (-10C at 500 mb) will accompany this trough, while only a modest strengthening of trough-preceding winds aloft is expected, given that the trough is somewhat removed from the stronger westerlies over the Canadian prairies. While some warm-sector cloud cover persists early today regionally, the boundary layer ahead of an eastward-moving cold front should become minimally inhibited by early into mid-afternoon, with MLCAPE reaching 2500+ J/kg especially across the eastern halves of Minnesota and Iowa, as well as much of western Wisconsin and far northwest Illinois. Initial thunderstorm intensification is expected this afternoon across northern/central Minnesota, potentially with an ongoing band of storms across northern Minnesota, and more so near the aforementioned front and surface wave, with subsequent scattered development southward into southeast Minnesota/eastern Iowa and western Wisconsin through late afternoon and early evening. Severe wind gusts and hail will be possible with a mixed mode of storms including multicells and some transient supercells. Some tornado risk may exist as well, mainly across northeast Minnesota/northwest Wisconsin. ....Middle Mississippi Valley/Ozarks/southern Plains... Widely scattered mid-level convection across the region trails a shortwave trough centered generally near the confluence of the Mississippi/Ohio Rivers. This convection is atop a warm-sector boundary layer that will heat and become strongly unstable by peak heating, particularly across eastern Oklahoma into Missouri western/northern Arkansas ahead of an east/southeastward-moving front. Isolated to widely scattered thunderstorms are expected to develop by mid/late afternoon near the front, and somewhat across the warm sector, potentially influenced by lingering cloud cover/zones of differential heating. While tropospheric winds will only be modest strength (effective shear less than 30 kt), strong heating, steep lapse rates, and ample buoyancy will support the potential for severe-caliber wind gusts, especially with the aforementioned corridor of greatest destabilization. Some severe hail may occur as well. $$ = = = 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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .