Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Aug 13 2023 19:47:18 ACUS01 KWNS 131947 SWODY1 SPC AC 131945 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Sun Aug 13 2023 Valid 132000Z - 141200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE OZARKS... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTH-CENTRAL PLAINS TO THE TENNESSEE VALLEY...AND PORTIONS OF NEW ENGLAND... ....SUMMARY... Severe thunderstorm wind gusts, large hail and a tornado threat are expected late this afternoon into tonight, especially across the south-central Plains and Ozarks. Other severe thunderstorms will persist into early evening across New England. ....20z Update... The overall forecast philosophy is unchanged from the 1630z outlook (see previous discussion below). The only minor change in severe probabilities is across parts of southeast MN into extreme southwest WI and eastern IA where the Marginal (level 1 of 5) risk has been expanded. This expansion is related to severe potential late tonight into early Monday morning associated with convection beneath the cold core of the upper shortwave trough and in the vicinity of the surface low. Damaging wind potential will continue this afternoon across the TN Valley as an ongoing MCS spreads east/southeast. Ref Severe Thunderstorm Watch 641 and forthcoming MCDs for short term severe trends. Additional isolated severe storms will continue the next several hours across parts of Maine and vicinity where Severe Thunderstorm Watch 640 is in effect until early 01z. Severe potential is expected to increase from late afternoon into this evening across the south-central Plains toward southern MO. See MCD 1982 for short term severe potential across parts of KS. Early day convection has modified and stabilized the low-levels across MO (per mesoanalysis and 18z SGF RAOB) and will likely delay convection until this evening as the airmass recovers and a low-level jet increases. Convection will then spread east/southeast from KS/OK along residual outflow/differential heating corridor posing an all-hazards risk. ...Leitman.. 08/13/2023 ..PREV DISCUSSION... /ISSUED 1154 AM CDT Sun Aug 13 2023/ ....South-Central Plains/Ozarks/Mid-South... The Lower Missouri Valley/Ozarks continue to be considerably influenced by persistent convection/MCVs at midday, with only modestly broken cloud cover across much of the warm sector ahead of the primary front. But a gradual trend of thinning/less prevalent cloud cover is noted from the west across the south-central Plains, which should allow for moderate to locally strong destabilization into/around peak heating. Deep convection is expected to develop in multiple zones by late afternoon/sunset, including across the middle Missouri Valley/eastern South Dakota vicinity near the surface low, and otherwise near the south/southeastward-moving front across southeast Nebraska and portions of Kansas, as well as across the Oklahoma/Texas Panhandles and western/northern Oklahoma. Some of this convection, as it evolves across eastern Kansas toward the Ozarks, will interface with residual differential heating and a weak residual boundary or two. Seasonally strong winds aloft will influence supercell-favorable hodographs, with large hail initially the primary hazard. Several clusters of storms should evolve by early evening, potentially including northern Oklahoma/southeast Kansas into the Ozarks, where a somewhat higher-probability for wind damage, along with some tornado potential, is expected to exist this evening, and possibly linger into the overnight. ....Tennessee Valley/southern Appalachians... On the northern fringe of the upper ridge and stronger capping aloft, a remnant cluster/MCV across far southeast Missouri/northeast Arkansas at midday will likely influence additional downstream convective development and intensification this afternoon within a moderate to strongly unstable environment. Westerlies remain a bit stronger than typical mid-August scenarios, and this should influence the persistence and organization of the storms, with some semi-organized multicellular clusters possible. Wind damage will be the primary hazard regionally. For additional details, see Mesoscale Discussion 1981. ....New England... A Slight Risk has been introduced for expectations of a somewhat greater severe-weather potential today. Isolated/widely scattered thunderstorms are expected to further develop through early afternoon along and ahead of the surface cold front. A moderately unstable environment and with deep-layer shear around 30-35 kt will support some organized multicells capable of severe hail and locally damaging wind gusts. For additional details, see Mesoscale Discussion 1980. $$ = = = 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) .