Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Nov 15 2023 12:43:44 ACUS01 KWNS 151243 SWODY1 SPC AC 151242 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0642 AM CST Wed Nov 15 2023 Valid 151300Z - 161200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Severe thunderstorms are not forecast. ....Synopsis/Discussion... The synoptic/upper-air pattern over the CONUS will be dominated by three troughs (and related smaller-scale features): 1. A northern-stream perturbation, splitting eastward out of mean troughing over the northeast Pacific, across BC and the Canadian Rockies. This feature should extend across much of SK and northern/western MT by 12Z tomorrow, remaining too removed from sufficient low-level theta-e to support thunderstorm potential despite cold air aloft. 2. A Pacific cutoff low, centered around 500-550 nm off the central CA coast, forecast to drift erratically southward/southwestward through the period. A basal shortwave trough is apparent in moisture-channel imagery approaching 130W, south of the main mid/ upper low, with sporadic lightning detected. This feature should eject northeastward across parts of the central/southern CA coastline between 00-03Z, while deamplifying. An associated band of enhanced large-scale DCVA/lift should precede the trough across the region and inland, steepening mid/upper-level lapse rates over a cool, moist, stable low-level profile. Elevated MUCAPE to around 500 J/kg is possible (rooted between 700-800 mb), amidst 35-40 kt effective-shear magnitudes. This indicates that the most vigorous cells may produce small hail or locally gusty winds through the stable low-level profiles. Organized severe appears unlikely. 3. A southern-stream trough -- initially apparent from central/ southern MS to a prominent low/middle-level vorticity max near the Mississippi River mouth, then across the central Gulf toward the Yucatan Peninsula. The low-level circulation should drift erratically near its present position today, then shift farther offshore and weaken tonight, as the trough aloft starts to eject away from the low-level vortex. A low-level baroclinic zone -- extending from the low east-southeastward over parts of south FL -- should remain quasistationary through the period. Mesobeta-scale oscillations of the diffuse surface boundary are possible in response to areas of precip (including embedded thunderstorms) to its north. Lapse rates, lift and deep shear each should remain too weak for overland severe. A few weak/shallow supercells may occur around the Keys, with slightly enlarged hodographs in deep low-level eaterlies, but weak flow aloft. The greatest convective coverage/intensity should remain over the open Gulf, where marine moisture/heat fluxes are maximized into the boundary layer near the Loop Current. ...Edwards/Gleason.. 11/15/2023 $$ = = = 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) .