Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Nov 12 2024 06:58:58 ACUS02 KWNS 120658 SWODY2 SPC AC 120657 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CST Tue Nov 12 2024 Valid 131200Z - 141200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER MS VALLEY AND NORTHEAST GULF COAST...FOR COASTAL WA/OR/NORTHERN CA... ....SUMMARY... A marginal tornado/wind threat is apparent on Wednesday afternoon into Wednesday night across a part of the central Gulf Coast States. Thunderstorms with strong to locally severe gusts are also possible near the immediate coasts of Washington, Oregon, and northern California. ....Synopsis... A mid/upper-level shortwave trough is forecast to move eastward from the Great Plains toward the Midwest and OH/TN Valleys on Wednesday. In conjunction with this shortwave trough, a weak surface low will move from the east-central Plains toward the Great Lakes region, as a trailing cold front moves through parts of the middle/lower MS Valley. Farther west, a deep mid/upper-level trough will progress farther inland across the western CONUS, as an embedded shortwave moves across northern CA into the interior Northwest. ....Lower Mississippi Valley/Central Gulf Coast region... Rich low-level moisture (with upper 60s to lower 70s F dewpoints) is forecast to gradually spread northward across the lower MS Valley region from later in the D1/Tuesday period into D2/Wednesday. Weak lapse rates will tend to limit instability, while stronger mid/upper-level flow will generally remain north of the richer moisture. However, deep-layer shear will likely become at least marginally supportive of organized storms, while some enhancement to low-level flow/shear is forecast as the shortwave trough to the north glances the region. This evolution could support a few marginal supercells and/or stronger clusters during the afternoon and evening, with a threat of locally damaging winds and possibly a tornado or two. Elevated storms will also be possible through the day/evening to the north of the richer surface moisture. While effective shear will be sufficient for a few strong elevated storms, the severe potential with northward extent will tend to be limited by weak midlevel lapse rates and generally marginal MUCAPE. ....WA/OR/northern CA coasts... Cooling temperatures aloft will support weak destabilization in the vicinity of the WA/OR/northern CA coasts through the day on Wednesday. While convection will be rather low-topped, instability may become sufficient (with SBCAPE potentially in the 200-500 J/kg range) for occasional thunderstorms. The strongest low-level flow will precede the primary destabilization, but persistent and rather strong deep-layer southwesterly flow could support modestly organized line segments and/or weakly rotating cells, with a threat of isolated severe convective gusts and perhaps some small hail. A brief tornado also cannot be ruled out, though the favored location (if any) of any longer-lived rotating cells remains uncertain at this time. ...Dean.. 11/12/2024 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .