Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 19 2025 08:52:11 ACUS48 KWNS 190852 SWOD48 SPC AC 190850 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Fri Sep 19 2025 Valid 221200Z - 271200Z ....DISCUSSION... A complex, split-flow, low-predictability upper pattern will exist early next week and eventually evolve into a closed upper low across the Midwest by the end of the week. The operational ECMWF and GFS have significantly different evolution of the upper pattern. However, the GEFS and EPS ensemble mean look very similar through much of the extended forecast. Therefore, the operational GFS will be treated as an outlier for this outlook cycle with an implied preference for the ECMWF/EPS/GEFS. ....Day 4/Monday - TX/OK Panhandles into western Kansas and western Oklahoma... ECMWF forecast soundings on Monday show a favorable environment featuring moderate to strong instability and moderate to strong shear as a 40+ knot mid-level jet ejects across the TX Panhandle and into Oklahoma. The primary trough will remain across the central Rockies with only weak height falls across the Plains. However, a strengthening low-level jet ahead of this trough may support thunderstorm potential within this favorable zone. Relatively weak synoptic support and lower predictability within the split-flow regime precludes 15% probabilities at this time, but probabilities may need to be included later, particularly if confidence in the location and coverage of storms across portions of OK/KS and the TX Panhandle increases. ....Day 5 and Beyond... If a closed upper-low develops (as forecast by the GEFS and EPS mean), some marginal severe weather concern will likely accompany the low as it drifts east. No specific periods of greater severe weather threat are apparent at this time, and given the slow forward speed of the closed low, any severe weather threat will likely remain marginal. ...Bentley.. 09/19/2025 = = = 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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .