Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 30 2023 20:00:07 ACUS01 KWNS 302000 SWODY1 SPC AC 301958 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Jul 30 2023 Valid 302000Z - 311200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA... ....SUMMARY... Severe thunderstorms should be most organized over parts of the northern/central Plains through tonight, with the greatest threat for very large hail and severe outflow gusts centered near the Black Hills. ....20Z Update... No changes have been made to severe probabilities across the northern/central Plains. See Mesoscale Discussion 1786 and recently issued Severe Thunderstorm Watch 573 for more details on the potential for very large hail and severe wind gusts with developing thunderstorms over the Black Hills of SD. Wind probabilities have generally been adjusted southward across parts of the Southeast based on the progression of loosely organized clusters ongoing across AL/GA. Reference Mesoscale Discussion 1787 for additional information on the threat for strong to damaging winds associated with this convection. ...Gleason.. 07/30/2023 ..PREV DISCUSSION... /ISSUED 1125 AM CDT Sun Jul 30 2023/ ....Northern Plains/MO Valley through tonight... Around the northern periphery of the central Rockies midlevel high, embedded speed maxima will continue to move eastward over MT and southeastward from the Dakotas to the upper MS Valley. Elevated convection is ongoing in a band of frontogenesis/warm advection from southern ND into northern SD, along the east edge of the steeper midlevel lapse rate plume. MUCAPE near 1500 J/kg and long hodographs with effective bulk shear in excess of 50 kt will continue to support the potential for elevated supercells capable of producing large hail and isolated strong outflow gusts as the storms spread southeastward through the afternoon. Farther west this afternoon/evening, additional storm development is likely across the northern High Plains in the zone of low-level upslope flow, and isolated storms may also form with daytime heating over the Black Hills. Very steep midlevel lapse rates noted in the 12z UNR sounding and relatively strong mid-upper flow/long hodographs will initially favor supercells capable of producing very large hail of 2-3 inches in diameter or greater. Some upscale growth is expected this evening as the storms move east of the higher terrain, with an increase in the potential for severe outflow gusts. The convection will likely persist overnight and develop southeastward toward middle/lower MO Valley as warm advection increases with a nocturnal low-level jet, with isolated large hail/damaging winds possible. ....Southeast this afternoon... A weak midlevel trough is moving slowly southeastward over northern MS/AL and the southern Appalachians. Isolated thunderstorms are ongoing along the wind shift across northern MS/AL, and this convection will likely increase through the afternoon as the low levels warm/destabilize to the south of the wind shift. Deep-layer flow/vertical shear will remain rather weak, so the primary threat will be downburst winds with multicell clusters through the afternoon. ....Southern AZ/southeast CA this afternoon/evening... Easterly flow aloft is established over AZ to the south of the Four Corners high, and on the northern periphery of a weak wave moving westward over northwest Mexico. Despite some moistening, 12z soundings still revealed steep lapse rates and the potential for deep inverted-V profiles across southern AZ this afternoon. Storms that form over the higher terrain will have the potential to spread westward over the lower deserts and produce isolated strong-severe outflow gusts. $$ = = = 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) .