Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Oct 11 2023 16:24:29 ACUS01 KWNS 111624 SWODY1 SPC AC 111622 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CDT Wed Oct 11 2023 Valid 111630Z - 121200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL TO NORTHERN FLORIDA... ....SUMMARY... Damaging thunderstorm gusts and a few tornadoes are possible this evening and tonight over parts of central/northern Florida to the coastal-bend region. Strong to severe thunderstorms over the central Plains and Midwest will be capable of severe hail late tonight. ....Synopsis... Mid-morning water-vapor imagery and upper-air analyses depict a strong mid/upper-level jet nosing into the central Rockies. Steady surface pressure falls have been ongoing over the past 24 hours along the high Plains ahead of this jet and the attendant upper wave, and are expected to intensify through tonight as a consolidated low deepens over western KS/NE. Over the Gulf, a surface low continues to gradually intensify within the right-entrance region of a broad mid-level jet. A diffuse residual frontal zone draped across the central Gulf and the FL Peninsula is forecast to gradually lift north as a warm front into north FL/south GA by 12 UTC Thursday. This frontal zone will be the focus of thunderstorm development today through tonight. ....Florida... Latest surface observations across FL show the diffuse nature of the frontal zone with low 70s across northern FL warming into the 80s to the south. The approach of the low through tonight will strengthen south/southeasterly flow and should result in a gradual northward progression of a frontogenetical warm front. However, some uncertainty regarding the placement of the front by 12 UTC remains owing to the influence of diabatic cooling driven by stratiform rain currently overspreading northern FL/southern GA. Regardless, 12 UTC soundings sampled a weakly capped environment with rich low-level moisture, which should support isolated to scattered thunderstorm development by mid-afternoon across the central/southern Peninsula. Kinematic fields will gradually improve through tonight and with forecast soundings suggesting 0-1 km SRH on the order of 100-200 m2/s2 and effective bulk shear around 40 knots between 03-12 UTC. These wind fields over the warm sector suggest that convection will increasingly pose a threat for severe wind and tornadoes heading into the overnight hours. However, there may be some spatial offset between the best kinematic environment closer to the warm front across north-central FL and the better buoyancy further south. The degree of overlap of favorable buoyancy/shear remains uncertainty, and will likely depend on the evolution of the stratiform rain field currently noted over the central Gulf to the north of deeper convection. ....Central Plains/Midwest... 12 UTC soundings across the Plains sampled very steep mid-level lapse rates between 8-9 C/km associated with the eastward advection of an elevated mixed layer emanating from the southern/central Rockies. Although the deepening surface low over KS/NE will strengthen southerly return flow through tonight, moisture return is expected to be inadequate to result in surface-based convection, but low-level moistening coupled with increasing isentropic ascent along a frontogenetical warm front later tonight should support elevated convection along the SD/NE border to northern IL. Effective bulk shear values between 30-40 knots will be supportive of storm organization with an attendant risk of large hail. This threat will likely be greatest across parts of southeast SD, northeast NE into IA and central IL, coincident with the steeper mid-level lapse rates/higher buoyancy. The hail risk is expected to be greatest with the initial development of discrete to semi-discrete cells, but weak storm motions out of the frontal zone should promote a tendency for clustering with time. ...Moore/Hart.. 10/11/2023 $$ = = = 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) .