Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Mar 20 2024 09:01:53 ACUS48 KWNS 200901 SWOD48 SPC AC 200900 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Wed Mar 20 2024 Valid 231200Z - 281200Z ....DISCUSSION... Medium-range models suggest that blocking centered over the northeastern Pacific will break down this weekend, as a more progressive regime shifts across the central into eastern mid-latitude Pacific, and gradually inland through much of the U.S. by the middle to latter portion of next week. Initially, flow downstream of the weakening blocking may undergo amplification, including mid-level troughing offshore of the southern Atlantic Seaboard, and larger-scale mid-level troughing progressing inland of the U.S. Pacific coast through the Great Plains and Mississippi Valley through early next week. Within the inland advancing troughing, there appears reasonable agreement between the ECENS/ECMWF, GEFS and GFS model output that a significant lead short wave perturbation will accelerate northeastward out of the Southwest across the southern Rockies late Sunday into Sunday night. As this occurs, a rather deep cyclone is forecast to continue to form to the lee of the Front Range during the day, before migrating southeastward then eastward into the adjacent high plains. Although it still appears that low-level moisture return in the wake of prior low-level drying and cooling across the northern Gulf Basin may still be on the margins for vigorous thunderstorms, the development of steep lower/mid-tropospheric lapse rates may compensate. Coupled with potentially intense wind fields and strong forcing for ascent, organized severe thunderstorm development seems probable late Sunday afternoon into Sunday night. This may include supercells initially, then an evolving narrow squall line. Into the early through middle portion of next week, uncertainties concerning a subsequent short wave emerging from the Southwest increase. However, it appears probable that there will be at least narrow corridors of strong to severe thunderstorm development on following days across the southeastern Great Plains into lower Mississippi Valley and perhaps parts of the Southeast. ...Kerr.. 03/20/2024 = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .