Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Sep 25 2023 19:56:16 ACUS01 KWNS 251956 SWODY1 SPC AC 251954 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0254 PM CDT Mon Sep 25 2023 Valid 252000Z - 261200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE FLORIDA PENINSULA AND SOUTH TEXAS TO SOUTHWEST LOUISIANA... ....SUMMARY... Isolated severe thunderstorms remain possible across southern parts of Texas, southwestern Louisiana, and the Florida Peninsula late this afternoon into this evening. ....20Z Update... No changes have been made to the severe probabilities. Isolated strong to potentially severe thunderstorms remain possible across parts of the FL Peninsula, and also across southern parts of Texas into southwest LA. See the previous discussion below for more information. Also see MCD 2196 for more information regarding the short-term threat near the upper TX coast. ...Dean.. 09/25/2023 ..PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Sep 25 2023/ ....Southern Texas/southwest Louisiana... Multiple areas of widely scattered showers and thunderstorms, generally in a weakening/diminishing trend through mid/late morning, exist across the region. Additional widely scattered thunderstorm development is expected to uptick in coverage and intensity later this afternoon, influenced by the southward-sagging front as well as several zones of outflow/differential heating. Multicellular storms will be common, with some potential for a few supercells particularly with westward extent across south-central/southwest Texas toward the Rio Grande, where deep-layer shear and buoyancy will be a bit stronger and where large hail potential is more apparent. This is aside from the potential for isolated severe wind gusts that will more broadly exist across the region. ....Central/southern Florida... Scattered thunderstorms are expected to develop across the region this afternoon. Localized strong/severe wind gusts are possible along with the possibility of marginally severe hail. This regime is the east of upper troughing over the central/northeast Gulf of Mexico, with a moist environment (PW 1.75-2.25-inches) existing across much of the Peninsula, with sea breeze boundaries focusing increasing diurnal thunderstorm development. While deep-layer winds will be weak, veering with height will contribute to 20-30 kt effective-shear magnitudes, supporting multicellular storm organization. Convection should diminish in coverage and strength after sunset as a combination of nocturnal cooling and increasingly prevalent outflow air stabilizes the boundary layer inland. ....Southeast MN/western WI/northeast IA/northwest IL... A few funnels may occur this afternoon across the region in relative proximity to the southeastward-moving upper low (-16C at 500mb), focused near the surface occluded front that will be located near the Mississippi River, and generally oriented parallel to it. There is where low-level buoyancy including 100-125 J/kg 0-3 km CAPE will be maximized with ambient vorticity. While a tornado cannot be entirely discounted, the potential for such currently appears to be very low, while funnels/briefly strong storms are otherwise plausible within the weak vertical shear environment (effective/0-6 km shear magnitudes less than 20 kt). $$ = = = 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) .