Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 15 2023 05:36:33 ACUS01 KWNS 150536 SWODY1 SPC AC 150534 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Fri Sep 15 2023 Valid 151200Z - 161200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN HIGH PLAINS... ....SUMMARY... Isolated severe thunderstorms are expected over the southern High Plains Friday afternoon and Friday night. ....Southern High Plains... Southern influence of Four Corners short-wave trough will shift into the southern Rockies later today. Latest model guidance maintains seasonally strong 500mb flow across NM into central TX with speeds on the order of 35kt during the afternoon/evening. Additionally, substantial midlevel cooling will spread across NM by peak heating where boundary layer lapse rates will be steepest along the western fringe of higher PW air mass. Early this morning, a weak midlevel disturbance was ejecting east along the TX/NM border. This feature appears partly responsible for small cluster of convection that has gradually organized near CVS. This activity is forecast to propagate southeast toward the Big Country by sunrise, then possibly continue southeast toward south-central TX by afternoon. Strong heating south of the boundary may result in additional surface-based storms evolving ahead of this activity where temperatures rise into the mid 90s. Weak upslope flow will persist across eastern NM today and strong surface heating will allow convective temperatures to be breached by mid afternoon. Forecast soundings across this portion of the high Plains exhibit supercell profiles with 35-40kt of surface-6km bulk shear. Steep lapse rates favor robust updrafts and isolated supercells are expected to develop then track southeast. Greatest risk with this activity should be hail and gusty winds, though a brief tornado can not be ruled out given the moist profiles and favorable low-level turning. ....Upper MS Valley... Narrow corridor of modest instability is expected to develop across the upper MS Valley from southern MN into northwest WI, immediately ahead of a progressive surface front. This boundary is supported by a strong short-wave trough that is digging southeast across SK/MB early this morning. Height falls ahead of this feature, along with strong heating near the boundary, suggest isolated thunderstorms could evolve by late afternoon. Forecast soundings do not exhibit much instability but strong shear does favor some potential for organization, albeit likely for only a few hours. Marginally severe hail appears to be the greatest risk with the isolated storms that evolve ahead of the front. ...Darrow/Bentley.. 09/15/2023 $$ = = = 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) .