Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 18 2023 01:00:50 ACUS01 KWNS 180100 SWODY1 SPC AC 180059 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Mon Jul 17 2023 Valid 180100Z - 181200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL/SOUTHERN HIGH PLAINS TO THE OHIO VALLEY AND FROM EASTERN WYOMING SOUTHEAST INTO SOUTHWEST SOUTH DAKOTA AND NORTHERN NEBRASKA...... ....SUMMARY... Severe storms producing large hail and damaging wind gusts are expected from the Black Hills southeastward into the central Plains tonight. Additional severe storms are possible and across portions of the Ozarks, ArkLaMiss, and Ohio Valley this evening. ....01z Update... A complex forecast scenario is evolving this evening with multiple clusters of severe storms ongoing. Severe probabilities behind the cold front across northern IN and northwest OH, as well as portions of MT and western ND have been trimmed. ....OK/KS Border... A large and persistent supercell ongoing across far southern KS is expected to continue to pose a risk for damaging winds and large hail as it tracks slowly south/southeastward this evening. Very large buoyancy (upwards of 5000 J/kg of MLCAPE) and 40-45 kt of effective shear will support a risk for significant hail as well. Some upscale growth, and an increase in the potential for damaging gusts is possible, but it remains uncertain how far south the severe risk will persist this evening. The SLGT risk was expanded farther south and west near the OK/KS/TX borders to cover the risk. ....ArkLaMiss... The initial cluster of severe storms across northern AR has shown signs of weakening after encountering a partially modified air mass early this evening. New development upstream over central/southern MO has shown greater propensity for clustering and cold pool development, suggesting some upscale growth is possible this evening. Model forecast soundings show a 30-35 kt low-level jet over eastern OK and western AR may aid in the development of a small MCS moving south across the ArkLaMiss. Uncertainty on the southward extent of severe probabilities is high, but a large reservoir of MUCAPE and 30-35 kt of vertical shear would be sufficient to support a risk for damaging gusts tonight if storms can develop a strong enough cold pool. ....Black Hills into the central Plains... The main change tonight was to join the SLGT risk areas across portions of eastern NE and northwest KS. Storms over eastern WY and western SD should continue to move southeastward this evening with a risk for damaging gusts and hail. As the low-level jet increases, low-level warm advection near a frontal zone should aid in additional storm development ahead of this cluster across the conjoined SLGT. Large elevated buoyancy and moderate vertical shear will support a risk for hail and damaging gusts into the overnight hours. ...Lyons.. 07/18/2023 $$ = = = 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) .