Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Oct 27 2023 12:47:56 ACUS01 KWNS 271247 SWODY1 SPC AC 271246 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0746 AM CDT Fri Oct 27 2023 Valid 271300Z - 281200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Organized severe weather is not expected through tonight. ....Synopsis... Positively tilted mid/upper-level troughing is forecast to amplify between the northern High Plains and northern CA through the period, thanks to a series of favorably positioned shortwaves in the associated cyclonic-flow field. That process will contribute to net height falls across most of the Southwest, central/southern Rockies, Upper Midwest, Upper Great Lakes, and Great Plains, between now and 12Z tomorrow. However, any substantial shots of large-scale DCVA/ ascent aloft, related to the shortwave troughs, should remain behind a strong and progressive surface cold front, which was analyzed at 11Z from a low in vicinity of IWD to near a line from LSE-MKC-OUN- FDR-ROW. By 00Z, the front should reach northern through southwestern Lower MI, as well as southern parts of IL/MO, northwestern AR, extreme southeastern OK, and central to southwest TX. By 12Z, the front is forecast from Lake Ontario southwestward over the lower Ohio Valley to the Arklatex region, becoming quasistationary over central/southwest TX to far west TX or extreme southern NM. ....Lower MI to central TX... Isolated to scattered thunderstorms are expected to develop this afternoon within a loosely organized, broken band of convection roughly along or just ahead of the front from Lower MI to the Ozarks, and mainly along and behind the front across the TX portion. Additional activity may form in a weakly capped warm sector over central/south TX, amidst modest lapse rates, but with rich enough low-level moisture (upper 60s to mid 70s F surface dewpoints) and enough diurnal heating to yield 1000-2000 J/kg MLCAPE. However, weak low/middle-level flow/shear will limit convective organization and keep severe potential too low-conditional for an outlook area. For flipped reasons (stronger shear but weaker instability), severe potential farther northeast across the IL-MI corridor is non-zero, but also too conditional/isolated for a categorical area at this time. Forecast soundings reasonably suggest that poor lapse rates in low levels, as well as above the boundary layer, will limit buoyancy substantially, despite seemingly favorable moisture. MLCAPE commonly under 800 J/kg will have to contend with stable layers at varying levels and depths in the thermodynamic profile, as well as entrainment (ECAPE) reductions. Long, nearly straight hodographs and 35-45-kt effective-shear magnitudes indicate at least transient/isolated storm-scale rotation may develop, so a few strong storms cannot be ruled out. ...Edwards/Goss.. 10/27/2023 $$ = = = 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) .