Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Dec 27 2022 12:47:48 ACUS01 KWNS 271247 SWODY1 SPC AC 271246 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0646 AM CST Tue Dec 27 2022 Valid 271300Z - 281200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Isolated lighting is possible near the coasts of northern California and Oregon. ....Synopsis/Discussion... A progressive upper-air pattern will continue across the CONUS, characterized by rising heights in most of the East, and falling heights across the West. The latter will occur ahead of a synoptic-scale trough -- currently located just offshore from the West Coast, with an embedded cyclone apparent in moisture-channel imagery centered about 175 nm west of UIL. Though the cyclone should dissipate around 18Z as it moves ashore in WA, the broader trough will amplify somewhat through the period. By 00Z, the trough should reach the inland Pacific Northwest and coastal northern CA. By 12Z tomorrow, the trough should be located from near the AB/SK border across northern MT to southern ID, central NV and southern CA. At the surface and in low levels, the western height falls will foster a broad area of falling heights/pressures east of the Rockies, along with return flow in a broad low-level warm-advection regime. However, with much of it still originating from an insufficiently modified continental/polar air mass, this return flow should be too dry to support thunderstorms through the period. Instead, a few lightning strikes are possible near portions of the central Pacific Coast prior to the passage of the trough. This will occur as cooling in midlevels extends upward into thermal layers supporting lightning production in a buoyant column, with enough moisture/theta-e in the marine layer for MLCAPE to at least briefly reach the 100-300 J/kg range. Small hail and strong gusts (somewhat above ambient strong gradient winds) may be noted from the most persistent/vigorous cells. ...Edwards.. 12/27/2022 $$ = = = 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) .