Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Sep 21 2023 19:50:52 ACUS01 KWNS 211950 SWODY1 SPC AC 211949 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Thu Sep 21 2023 Valid 212000Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF WESTERN KS AND WESTERN/CENTRAL NE...AND OVER PARTS OF SOUTHERN OK AND NORTH TX... ....SUMMARY... Widely scattered strong to severe thunderstorms are possible this afternoon into tonight across parts of the southern and central Plains. ....20Z Update... ....NE/KS... Recent surface analysis places a low near the CO/NE/KS border intersection, with a dryline extending southward across western KS. As mentioned in recently issued MCD #2168, storm initiation appears probable in the next couple of hours across parts of southwestern Nebraska. The deepening surface low is supporting robust southeasterly flow and strong low-level shear. Moderate westerly flow exists atop this low-level southeasterly flow, supporting 30 to 40 kt of effective bulk shear. Strong buoyancy has also developed ahead of the dryline, with recent mesoanalysis estimating 1500 to 2500 J/kg MLCAPE across western KS and western/central NE. The overall environment supports supercells capable of all severe hazards including large to very-large (1-3 in.) hail, severe wind gusts (60-70 mph), and tornadoes. The tornado threat will generally be maximized near the warm front where surface winds remain more backed. ....Southern OK/North TX... Despite widespread clouds, temperatures have reached the upper 80s/low 90s across much of the region. Dewpoints are in the upper 60s/low 70s, and this combination of temperatures and dewpoints is supporting strong buoyancy. Recent mesoanalysis estimates MLCAPE is around 2000-2500 J/kg. Vertical shear is modest, but sufficient for some updraft organization. As such, a few strong to severe thunderstorms remain possible, with large hail and damaging gusts as the primary threats. ...Mosier.. 09/21/2023 ..PREV DISCUSSION... /ISSUED 1112 AM CDT Thu Sep 21 2023/ ....Central and Southern Plains... Morning water vapor imagery shows a subtle shortwave trough crossing the Rockies of central CO. This feature will move eastward and provide weak large scale ascent across much of the central Plains this afternoon and evening. Morning model solutions are diverse in placement/timing of thunderstorm activity, but generally show a larger envelope of potential risk. Therefore have expanded the MRGL to include much more of the central and southern Plains. ....NE/KS... A rather pronounced surface dryline is expected to develop later today from western NE southward into western KS, with dewpoints in the 60s and MLCAPE values of over 2500 J/kg to the east of the boundary. Given the weak forcing and some cap, the areal coverage of convective initiation is uncertain. However, any storm that forms along this axis will have a conditional threat of very large hail and a tornado or two. These storms may persist for several hours after dark and track eastward into parts of north central KS and central NE. ....OK/TX... A weak sub-tropical shortwave trough is moving into west TX. Lift ahead of this feature is resulting in a large region of accas and a few showers and thunderstorms moving into southwest OK/northwest TX. Continued daytime heating is expected to lead to convective intensification by late afternoon across north TX and southern OK. The strongest cells in this area may produce hail and gusty winds for a few hours into this evening. ....Eastern NC... The outer bands of the strengthening tropical system off the southeast Atlantic coast are forecast to still be well offshore by Fri/12z. Therefore will defer any increasing tornado risk to the Day2 period. $$ = = = 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) .