Subj : DAY1SVR: Enhanced Risk To : All From : Mike Powell Date : Wed Jun 21 2023 16:08:00 ACUS01 KWNS 212002 SWODY1 SPC AC 212000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Wed Jun 21 2023 Valid 212000Z - 221200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF EASTERN COLORADO...SOUTHEAST WYOMING...AND THE NEBRASKA PANHANDLE...AND FROM THE EASTERN TEXAS PANHANDLE AND WESTERN OKLAHOMA INTO CENTRAL TEXAS... ....SUMMARY... Intense severe thunderstorms are expected late this afternoon into this evening over parts of the central and southern Plains, where severe gusts, very large hail, and a few tornadoes are possible. ....20Z Update... The Marginal and Slight Risks have been trimmed over parts of OK, in the wake of an earlier storm cluster that has since weakened. Otherwise, the previous forecast reasoning remains valid. ....Eastern CO/Southeast WY Intense supercell development is underway across northeast CO into the NE Panhandle, with additional supercells expected later this afternoon into this evening farther west toward the CO Front Range and southeast WY. Very large hail, severe gusts, and a few tornadoes will be possible in this area. See MCD 1188, WW 349, and WW 350 for more information regarding the threats in this area. ....Extreme southwest KS into the TX/OK Panhandles and northwest TX... A separate zone of intense supercell development is expected late this afternoon from extreme southwest KS into the TX/OK Panhandles, within a region of very rich low-level moisture, steep midlevel lapse rates, and strong to extreme buoyancy. Very large hail, severe wind gusts, and a couple of tornadoes will be possible with initial supercells. Some upscale growth is possible this evening, which may result in a larger swath of destructive wind gusts as storms move southeastward, though the areal extent of MCS development remains somewhat uncertain, as a westward-moving outflow may result in a narrowing of the instability axis with time. See MCD 1189 and WW 351 for more information regarding the short-term threat in this area. ...Dean.. 06/21/2023 ..PREV DISCUSSION... /ISSUED 1123 AM CDT Wed Jun 21 2023/ ....TX/OK... Morning water vapor imagery shows a large upper trough over the western states, with moderately strong southwesterly mid-level winds across much of the central and southern High Plains. At the surface, an extremely moist and potentially unstable air mass (dewpoints in the mid 70s) is present from the eastern TX Panhandle eastward into western OK, and extending southeastward into central TX. Full heating will lead to afternoon MLCAPE values of 5000-6000 J/kg and minimal cap. Large scale forcing is weak, but circulations along the surface dryline will lead to rapidly thunderstorm development from extreme southwest KS into the eastern TX Panhandle. These storms are likely to be supercells capable of very large hail and a few tornadoes. These storms are likely to slowly congeal into one or more bowing complexes by mid evening, tracking southeastward into northwest and central TX. Several morning CAM solutions suggest the potential for a corridor of significant wind damage if this scenario unfolds. ....Eastern CO/Southeast WY... An extremely moist and unstable low-level air mass is streaming into the central High Plains, with dewpoints in the 70s being transported westward into the higher elevations of the eastern CO/southeast WY plains. Strong daytime heating and steep mid-level lapse rates will yield afternoon MLCAPE values over 3000 J/kg. All morning CAM solutions agree on the development of scattered thunderstorms by mid-afternoon along the front range and foothills, as well as the DCVZ along the Palmer Ridge. A combination of backed low-level winds and 30+ knots of southwesterly flow aloft will promote supercell structures capable of very large hail and a few tornadoes. The threat of severe storms may persist much of the evening, building southward along the Front Range into southeast CO. $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .