Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri May 12 2023 01:07:53 ACUS01 KWNS 120107 SWODY1 SPC AC 120105 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0805 PM CDT Thu May 11 2023 Valid 120100Z - 121200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN AND CENTRAL PLAINS... ....SUMMARY... Scattered severe thunderstorms are expected this evening across parts of the Great Plains centered on Kansas and Oklahoma. The greatest threat for a couple strong tornadic supercells should exist across central and southern Oklahoma. Isolated severe storms will also be possible in parts of the Southeast. ....Southern and Central Plains... The latest water vapor imagery shows an upper-level low moving into the central High Plains with southwest mid-level flow located across much of the southern and central Plains. At the surface, a moist airmass is located across the eastern half of Texas extending northward into much of Oklahoma, where surface dewpoints are generally from the mid 60s to the lower 70s F. Further northwest, into northwest Kansas and southwest Nebraska, surface dewpoints are generally in the 50s F. The airmass across the southern Plains is moderately to strongly unstable, with the RAP showing MLCAPE from north Texas into central Oklahoma in the 2500 to 3500 J/kg range, in agreement with the Norman 00Z sounding. This sounding also has moderate deep-layer shear with some directional shear in the boundary layer. This is contributing to 0-6 km shear near 40 knots which will be favorable for continued supercell development this evening. Supercells will be capable of producing tornadoes, wind damage and large hail, with the more intense updrafts likely generating hailstones of greater than 2 inches in diameter. As cell coverage gradually expands across the southern and central Plain, large hail will become likely across much of central and northern Oklahoma, extending northwestward into south-central Kansas. Concerning the tornado threat, the 00Z Norman sounding has 0-3 km storm relative helicity near 250 m2/s2. A clockwise hodograph is evident with winds increasing to about 25 knots near 850 mb. On the sounding, significant tornado parameter is around 2, which suggests there will be a potential for strong tornadoes with the more intense and well-developed supercells. The greatest threat for strong tornadoes will exist from near the Red River northward to the vicinity of Oklahoma City, where instability and low-level shear is currently maximized. Supercells will also be associated with a wind-damage threat. The wind-damage threat could increase as cells merge and multicell line segments organize. The severe threat across the southern and central Plains will likely continue into late evening and the early overnight period. ....North-central States... An upper-level low will move across the central High Plains this evening, as mid-level flow remains from the south and southeast from Nebraska into the Dakotas. Surface dewpoints are generally in the 50s F across this area, where the RAP is analyzing MLCAPE generally in the 500 to 1000 J/kg range. Regional WSR-88D VWPs have the strongest deep-layer shear across western and central Nebraska, where isolated supercells will be possible. A few of the stronger storms could produce hail and marginally severe winds. ....Southeast... The latest surface analysis shows a moist airmass in place across the central and eastern Gulf Coast states, with surface dewpoints generally in the 60s F. This is contributing to moderate instability with MLCAPE in the 1000 to 2500 J/kg range. A decaying MCS is ongoing within this moist airmass in the central Gulf Coast states. Although deep-layer shear across this area is relatively weak, steep low-level lapse rates will be sufficient for a marginal wind-damage threat for a few more hours this evening. ...Broyles.. 05/12/2023 $$ = = = 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) .