Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Dec 04 2022 19:51:43 ACUS01 KWNS 041951 SWODY1 SPC AC 041950 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0150 PM CST Sun Dec 04 2022 Valid 042000Z - 051200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... The risk for thunderstorms appears negligible across much of the U.S. this afternoon through tonight. ....20Z Update... ....Northern California... Orographic forcing along the western slopes of the northern Sierra Nevada might still contribute to isolated convective development vigorous enough to pose some risk for producing lightning. However, in the wake of one perturbation pivoting around the periphery of the offshore low, mid-levels are in the process of gradually warming from southwest to northeast. Even with insolation this afternoon, this will tend to limit further boundary-layer destabilization, which remains negligible at this time. Otherwise, widely scattered convection capable of producing lightning remains possible near immediate coastal areas, mainly late this evening into the overnight hours with the approach of the remnant upstream cyclonic mid-level circulation. ....Southwest... A continued increase in low-level moisture may now be contributing to weak conditional boundary-layer instability across southeastern Arizona into adjacent portions of southwestern New Mexico. However, VWP from Tucson indicates that low/mid-level wind fields have been gradually veering through the day, in the wake of one weak low-amplitude mid-level perturbation. And model output generally suggests that forcing associated with any upstream perturbations will be weaker and largely confined to areas near or south of the international border late this afternoon into tonight. ...Kerr.. 12/04/2022 ..PREV DISCUSSION... /ISSUED 1010 AM CST Sun Dec 04 2022/ ....Discussion... A mid/upper-level low west of the OR/CA border area will drift towards the coast through early Monday. Bands of ascent associated with embedded perturbations along with moderately steep lower-level lapse rates and weak buoyancy will support potential for isolated thunderstorms from the northern CA coast into the Sacramento Valley through tonight. Small hail is possible in low-topped convection along the immediate coast where buoyancy should be relatively greater, but the bulk of strong mid/upper speed shear will exist above the buoyancy profile owing to a pronounced inversion between 500-350 mb. Weak elevated convection will remain possible across southeast AZ and far southwest NM, within a persistent subtropical moisture plume. Scant buoyancy might support sporadic lightning flashes. $$ = = = 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) .