Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Oct 23 2023 12:33:03 ACUS01 KWNS 231232 SWODY1 SPC AC 231231 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0731 AM CDT Mon Oct 23 2023 Valid 231300Z - 241200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF SOUTHWEST TX AND THE UPPER MS VALLEY... ....SUMMARY... A brief tornado is possible across a portion of southwest Texas this evening into tonight. Isolated large hail will be possible late tonight across parts of the Upper Mississippi Valley. ....Big Bend to western Edwards Plateau of TX... A persistent fetch of gradually increasing low-level moisture is forecast across this region to the east of a weak surface trough/diffuse dryline. A cirrus canopy associated with the decayed remnants of TC Norma will act to limit the overall magnitude of destabilization. However, weak buoyancy is expected to develop and episodic bouts of isolated to scattered thunderstorms will focus from the Big Bend north-northeast across the western Edwards Plateau, mainly this evening through tonight. A strengthening low-level jet during this time frame will enlarge hodographs and may be sufficient for a transient supercell or two. But weak lapse rates through much of the vertical column will likely mitigate a threat beyond a low probability for a brief/weak tornado. ....Upper MS Valley... A low-amplitude shortwave trough near the MN/IA border has aided in scattered showers/thunderstorms this morning. In its wake, a capping inversion will likely limit renewed thunderstorm activity until at least the late evening when a southwesterly low-level jet becomes maximized across parts of NE/KS/IA. This will probably result in a west-east oriented band of thunderstorms overnight. But above-average spread does exist across guidance in terms of spatial and temporal extent of storm development, perhaps related to the lack of a focused shortwave impulse compared to this morning and handling of capping around 700 mb. As such, have expanded the level 1/MRGL area to account for greater areal uncertainty. Conditionally, ample elevated buoyancy owing to the plume of steep mid-level lapse rates will favor potential for isolated large hail. Despite strengthening upper-level flow late in the period, modest effective bulk shear should tend to favor multicell clustering and mitigate a more substantial severe hail threat. ...Grams.. 10/23/2023 $$ = = = 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) .