Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Nov 17 2023 12:45:51 ACUS01 KWNS 171245 SWODY1 SPC AC 171243 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Fri Nov 17 2023 Valid 171300Z - 181200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ....Synopsis/Discussion... In mid/upper levels, large-scale troughing will prevail over eastern North America through the period. Associated cyclonic flow will be traversed by several shortwaves, including one evident in moisture- channel imagery from Lake Superior to eastern Kansas. The northern part of this perturbation will move southeastward to the lower Great Lakes, lower Ohio Valley and Ozarks by 00Z, then split, with the northern part being absorbed into a trailing perturbation now over the eastern Dakotas. The southern part should extend from western NC to central MS by 12Z. An associated surface cold front -- analyzed at 11Z from Lake Huron and southern Lower MI across central parts of IL/MO to southwestern OK and northwest TX -- will move southeastward by 00Z to northern NY, western PA, eastern parts of KY/TN, southern MS, central/southern LA, and southeast TX. Low-level moisture is very limited in the prefrontal return flow, which consists of mostly recycled continental/polar air behind a prior front. Still, low- density MUCAPE of 100-300 J/kg -- sometimes extending into icing layers suitable for lightning -- may support sporadic thunder within a near-frontal precip belt over parts of the Ohio Valley to southern Appalachians. Elsewhere, a southern-stream shortwave trough and associated low/ middle-level cyclone were evident over the coastal east-central FL vicinity. These will support isolated thunder potential today over parts of FL, then tonight in the NC Outer Banks area as the low-level circulation moves/redevelops northeastward to the east of the Carolinas. In the West, an initially cut-off cyclone centered near 35N132W will devolve to a progressive, open-wave trough by this evening, as heights fall to its northwest from a strongly progressive shortwave over the northeastern Pacific. The lead trough will move ashore over CA near the end of the period. Cooling/destabilization aloft will support episodic belts of convection -- including some thunderstorms, across parts of north-central to coastal southern CA today and tonight. Small hail and strong gusts may occur, but organized severe is not expected. Diurnal heating may yield MLCAPE up to about 500 J/kg, but with the trough still well offshore this afternoon, deep shear and low-level hodographs still should be limited. Colder air aloft, in the zone of strongest DCVA preceding the trough, will support showers and isolated thunderstorms this evening into tonight. Strengthening lift with low-level warm advection and collocated southwesterly moisture transport should support increasing precip late tonight over parts of AZ, including isolated to widely scattered thunderstorms. In the low-level source area, surface dewpoints already are in the 60s F from portions of south-central AZ across western Sonora, central parts of Baja and intervening waters. ...Edwards.. 11/17/2023 $$ = = = 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) .