Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Nov 28 2023 05:07:52 ACUS01 KWNS 280507 SWODY1 SPC AC 280506 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 PM CST Mon Nov 27 2023 Valid 281200Z - 291200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... The risk of thunderstorms appears negligible across much of the U.S., today through tonight. ....Synopsis... Split westerlies emanating from the mid-latitude Pacific will continue to converge into broad, deep troughing east of the Great Plains into the western Atlantic. Within this regime, models indicate that one significant short wave perturbation, crossing the lower Great Lakes/upper Ohio Valley at the outset of the period, will fairly rapidly pivot across the northern Atlantic Seaboard by early this evening. However, broadly cyclonic northwesterly mid-level flow appears likely to linger across and east of the Mississippi Valley. Cool to cold, dry and stable conditions will generally be maintained beneath this regime, while downslope warming contributes to moderating temperatures across much of the Great Plains. Upstream, within a branch of westerlies across the southern mid-latitude eastern Pacific into the Southwest, mid-level troughing is forecast to dig across the California coast, with an embedded weakening low and associated occluding surface cyclone approaching the San Francisco Bay area by 12Z Wednesday. A modest plume of moisture will generally remain focused along the occluding boundary near/offshore of California coastal areas through the period, but the mid-level cold core may begin to spread inland across northern through central California coastal areas by the end of the period. ....Lower Great Lakes region... Steep lapse rates beneath the lower/mid-tropospheric cold core will be maintained beyond 12Z this morning. Forecast soundings, mainly over/near the relatively warm lake waters (particularly near southeastern Lake Ontario coastal areas), suggest that this may continue to contribute to thermodynamic profiles potentially conducive to low-topped convection capable of producing lightning, possibly into the midday or early afternoon hours. ....California coast... Due to the occluding and weakening nature of the approaching surface cyclone, and its offshore forecast track, the potential for appreciable boundary-layer destabilization inland of coastal areas near San Francisco Bay appears quite low. While mid-level cooling ahead of the modest mid-level cold core (including 500 mb temperatures of -22 to -24C) may contribute to convective development capable of producing lightning offshore of coastal areas, lightning production with the convection may tend to wane as it reaches central California coastal areas late tonight into early Wednesday. ...Kerr.. 11/28/2023 $$ = = = 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) .