Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Nov 05 2023 05:43:47 ACUS01 KWNS 050543 SWODY1 SPC AC 050541 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Several rounds of scattered thunderstorms are expected across the Pacific Northwest this afternoon through early Monday morning. ....Synopsis... The upper-level ridge across the central CONUS will flatten through the day on Sunday. Farther west, a mid-level trough will approach the Pacific Northwest coast. At the surface, a surface low will develop across the northern Plains in response to a shortwave moving through the region. In addition, a surface low will develop off the Oregon coast and approach the Pacific Northwest coastline near the end of the period. ....Pacific Northwest Coast... Temperatures will start to cool aloft by later this afternoon off the Oregon coast. These cooling temperatures over the marine airmass will result in an increase in thunderstorm activity during the afternoon which will persist through the overnight period. Forecast soundings show marginal instability (~250 J/kg MLCAPE) and strong shear with some low-level turning. The most favorable period for rotating updrafts and potentially some enhanced low-level rotation is expected late in the period 06Z to 12Z when the surface low approaches the coast. As this occurs, cooling temperatures aloft should result in maximum instability with some backing surface winds ahead of the approaching surface low. This pattern loosely matches previous patterns which have resulted in tornadoes in the northern California/Oregon coast environment. However, at this time, forecast instability and low-level streamwise vorticity remains too limited for a marginal risk along the coast. ...Bentley.. 11/05/2023 $$ = = = 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) .