Subj : DAY1SVR: Day 1 Convective To : All From : Mike Powell Date : Tue Sep 05 2023 06:58:00 ACUS01 KWNS 050549 SWODY1 SPC AC 050548 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Tue Sep 05 2023 Valid 051200Z - 061200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER MISSISSIPPI VALLEY... ....SUMMARY... Isolated severe storms -- accompanied primarily by hail/wind potential -- will be possible on Tuesday across parts of the Upper Mississippi Valley. Gusty winds are also possible with isolated storms across the mid Mississippi Valley into portions of the southern Plains. ....Upper Mississippi Valley... Strong short-wave trough is progressing east across the northern High Plains early this morning. Latest water-vapor imagery depicts a well-defined mid-level vort near the Black Hills. This feature is forecast to eject across SD early in the period before approaching the SD/MN border around 05/00z. Associated surface front should sag southeast across northwestern MN by mid day as a weak surface low advances east across the upper MS Valley. Latest radar data depicts a notable MCS has evolved over eastern ND with a progressive-propagating squall line now spreading toward northwest MN. This activity should spread into southeast MB/northwest ON early in the period. By late morning, model guidance suggests boundary-layer heating will aid destabilization immediately ahead of the wind shift across northern/central MN. Renewed convection should initiate along the wind shift by 18z then spread/develop east toward the Arrowhead/northwestern WI. Forecast soundings exhibit substantial flow/shear for supercells and initial convection may be supercellular in nature. Thermodynamic profiles favor hail and wind with this activity. Strong deep-layer flow and adequate low-level shear suggest some tornado potential, but this should be secondary to the hail/wind threat. ....Mid MS Valley/Southern Plains... As the northern Plains short-wave trough advances toward the MS Valley, stronger mid-level flow will spread across KS toward MO. Some increase will likely be noted at lower latitudes into northern OK/AR. There is increasing concern that isolated severe storms will evolve along the southern influence of the short wave where intense surface heating is expected ahead of the front. Latest model guidance suggests a deep boundary layer along a corridor from northwest TX, across central OK into southeast KS by late afternoon. Forecast soundings suggest convective temperatures will be breached between 22Z and 00Z as temperatures soar to near/just above 100F. With seasonally high PW values, it appears gusty downbursts may be noted with this activity. At this time will introduce a MRGL to account for this threat, but some large-scale support appears possible across southeast KS into MO as the ridge is suppressed. This activity could be a bit more organized than convection farther southwest along the wind shift across central OK into northwest TX. ...Darrow/Wendt.. 09/05/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .