Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 29 2023 05:30:10 ACUS01 KWNS 290530 SWODY1 SPC AC 290528 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1228 AM CDT Fri Sep 29 2023 Valid 291200Z - 301200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MISSOURI VALLEY INTO MINNESOTA... ....SUMMARY... Scattered storms may produce hail or isolated severe gusts over parts of the Upper Missouri Valley into Minnesota today. ....Synopsis... Weak upper-level troughing will move through the Mid-Atlantic and southern New England this afternoon as well as northern/central Florida late in the period. In the northern Plains, a relatively strong upper-level shortwave will lift northeast through the eastern Dakotas and northern/central Minnesota early in the day. In its wake, upper-level ridging will increase within the Mississippi/Missouri Valleys. Farther west, an upper trough will deepen and dig into California and the western Great Basin. Thunderstorms are probable in parts of the Mid-Atlantic and Florida. Weak shear and relatively poor lapse rates should keep the potential for severe weather low. ....Parts of Upper Missouri Valley into Minnesota... Convection is likely to occur early in the day as the shortwave trough moves through the region and low-level warm advection remains strong. The strongest of these elevated storms would be capable of marginally severe hail given deep-layer shear of 35-40 kts and sufficient MUCAPE (generally 1000-1500 J/kg). A strong wind gust would be possible, but low-level stability should keep such activity quite isolated. Later into the afternoon/early evening, additional storm development is possible along either the cold front or effective warm front/composite outflow. Several factors contribute to the uncertainty in this scenario. First, the shortwave trough will be moving away and modest height rises aloft will be occurring during the afternoon. Second, warm air around 800 mb was present on the 00Z observed ABR and MPX soundings. This is at least somewhat present on forecast sounding for this afternoon. That being said, areas of heating near the surface boundaries may be enough to initiate isolated to potentially widely scattered storms. Some development would also be possible as a modest low-level jet develops during the early evening. Should storms form, shear, though weaker than earlier in the day, will be sufficient for marginal supercell structures. Marginally severe hail and damaging winds would be the primary threats. Low-level flow/shear will remain weak with only modest enhancement expected during the early evening. By that time, however, storms are much less likely to be surface-based. ...Wendt/Lyons.. 09/29/2023 $$ = = = 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) .