Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Nov 18 2023 19:50:27 ACUS01 KWNS 181950 SWODY1 SPC AC 181948 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Sat Nov 18 2023 Valid 182000Z - 191200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Organized severe thunderstorms are unlikely through tonight. ....20Z Update... The categorical (10 percent probability) thunderstorm line has been adjusted, mostly to account for the progression of synoptic features. Across California, in the wake of one short wave trough progressing across and east of the northern Sierra Nevada, weak mid-level warm advection is ongoing across much of the Sacramento/San Joaquin Valleys. While increasing breaks in the overcast may allow for boundary-layer warming to contribute to weak destabilization, orographic ascent, associated with an increasingly upslope component along the western slopes of the Sierra Nevada, appears the most prominent potential forcing for any thunderstorm development. Otherwise, increasing low-level convergence across the northern Sacramento Valley vicinity might provide another focus for thunderstorm development, mainly after 00-02Z, as mid-level forcing for ascent and cooling (within the exit region of a 100+ kt 500 mb jet) spread inland near and north/northeast of Eureka. ...Kerr.. 11/18/2023 ..PREV DISCUSSION... /ISSUED 1030 AM CST Sat Nov 18 2023/ ....Discussion... Aside from the potential for a lightning flash or two near (but primarily off) the eastern Florida coast, greater lightning coverage will remain confined to southwestern and, later, south-central portions of the country. This convection will be associated with the continued advance/evolution of large-scale upper troughing across the western half of the country (and, downstream, the associated low-level warm advection that will occur later in the period in tandem with low-level jet development over western portions of the Plains). Beneath the trough during the afternoon, low-level and deep-layer wind profiles across the Central Valley of California will remain conditionally supportive of organized convection. However, widespread cloud cover persists across the area, which should remain the case through the afternoon, when low-level shear will become maximized (followed by a weakening into the early evening hours). As such, destabilization potential will remain minimal -- which is supported by new/12Z model guidance showing minimal buoyancy at best. Thus, any potential for a brief tornado appears too low to include in an areal outlook. $$ = = = 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) .