Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Feb 13 2023 12:57:10 ACUS01 KWNS 131257 SWODY1 SPC AC 131255 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0655 AM CST Mon Feb 13 2023 Valid 131300Z - 141200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Severe-thunderstorms potential appears minimal today and tonight. ....Synopsis... Unification of northern and southern streams is forecast in mid/upper levels, as a mean trough develops across the western CONUS. This will be driven mainly by a couple well-developed, closely spaced, northern-stream shortwave troughs. The leading one is located from southern BC across northwestern WA to just offshore from the Pacific Northwest, and is forecast to move east- southeastward across ID to central MT, western WY and northern parts of UT/NV by 12Z tomorrow. Meanwhile, the trailing perturbation -- apparent in moisture-channel imagery over the Gulf of Alaska, will dig southeastward to the coastal Northwest and extreme northern CA before the end of the period. Phasing/merger will begin around then, between the southwestern end of the leading perturbation and the southeastern segment of the trailing one. This will contribute to a larger-scale troughing and cyclonic flow covering much of the Great Basin and West Coast States. Cold air aloft, related steep low/middle-level lapse rates, and marginal low-level Pacific moisture will contribute to isolated thunder potential mainly west of the Cascades. ....AZ/NM... As those processes occur upstream, a deep-layer cyclone -- initially centered over the YUM area -- will modify gradually into a strong open-wave trough and eject northeastward, reaching eastern AZ and Sonora by 00Z, and the central/southern High Plains by 12Z, with a surface low then over southeastern CO. Associated low-level warm advection and limited moisture will underlie strong DCVA/cooling in middle levels, near a low-level Pacific cold front. Associated lift should contribute to thunderstorm potential across much of AZ and western/central NM, into the Four Corners area. Though the convection will be rooted in elevated buoyancy, the potential for a dry/well-mixed, mid/late-afternoon boundary layer with "inverted-V" thermodynamic profiles beneath the convection and near the front, may support locally strong convective gusts today over parts of central to northwestern NM. The severe threat is too conditional/ isolated for an outlook area, given the weak buoyancy (less than 300 J/kg MUCAPE atop immediately preconvective surface temperatures in the 30s to low 50s, elevation-dependent). ....Southern Plains... A strong low-level warm-advection and moisture-transport regime is expected through the period ahead of the ejecting trough/cyclone. By this evening and into tonight, this will lead to widespread but weak elevated MUCAPE (50-400 J/kg in most areas) ahead of the low-level cold front, from eastern NM across west/northwest TX, western/central OK and southern KS. The frontal lift zone and nearly collocated DCVA/ascent plume will exit the southern Rockies and ranges of central/southern NM by around 00Z, then move quickly eastward over the southern Plains, supporting a plume of convection and precip, with widely scattered to scattered embedded thunderstorms. Despite a 55-70-kt LLJ and strong deep-layer flow above that, boundary-layer stability and lack of greater buoyancy aloft should limit surface downdraft intensity. Severe-gust potential tonight currently appears too low for an unconditional outlook here as well. However, an isolated gust near severe limits, penetrating the stable layer somewhere between central TX and southern KS, may not be out of the question. ...Edwards/Mosier.. 02/13/2023 $$ = = = 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) .