Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 24 2025 07:30:18 ACUS03 KWNS 240730 SWODY3 SPC AC 240729 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Thu Jul 24 2025 Valid 261200Z - 271200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SATURDAY THROUGH SATURDAY NIGHT ACROSS PARTS OF THE MIDWEST INTO SOUTHERN PORTIONS OF THE GREAT LAKES REGION AND ACROSS PARTS OF THE NORTHERN ROCKIES INTO THE DAKOTAS... ....SUMMARY... Strong thunderstorms accompanied by potentially damaging wind gusts are possible Saturday through Saturday night, across parts of the Midwest into southern Great Lakes region and across parts of the northern Rockies into the Dakotas. ....Discussion... Models indicate that weak mid-level troughing inland of the Pacific Northwest and across California into the Great Basin will persist through this period, but mid-level heights downstream across the Rockies, much of the Great Plains/Mississippi Valley and adjacent portions of southern Canada are forecast to rise within consolidating large-scale anticyclonic flow. Farther east, subtle mid-level troughing associated with a couple of perturbations may overspread the Great Lakes region. In lower latitudes, it appears that the prominent center of highest mid-level heights (in excess of 594 dm at 500 mb) will begin expanding westward out of the Southeast, toward the central and southern Great Plains. However, a weak wave on its southern periphery may continue slowly inland of the northwest Gulf coast. In lower levels, a remnant frontal zone may become increasingly diffuse while advancing offshore of the northern and middle Atlantic Seaboard, and returning northward through southern portions of the Great Lakes. ....Midwest into southern Great Lakes Region... Confidence is low, but models suggest that a possible convectively augmented perturbation may progress east of the Dakotas through the upper Great Lakes region during this period, with another convectively generated or augmented perturbation, emerging from the Great Plains to its south, turning eastward across the Midwest into southern portions of the Great Lakes. It appears that this may be accompanied by a belt of 20-40 kt westerly lower/mid-tropospheric flow. With the boundary-layer becoming characterized by seasonably high moisture content and sizable CAPE, along and south of the remnant frontal zone by Saturday afternoon, mid-level forcing for ascent may support an evolving cluster of storms. Although mid-level lapse rates may be modest to weak, the modest shear/westerly deep-layer mean flow may be sufficient to support a developing risk for strong to severe wind gusts as activity progresses eastward, aided by heavy precipitation loading and evaporative cooling/melting in downdrafts. ....Northern Rockies into the Dakotas... Confidence is low due to uncertain forcing for convective development across the northern Rockies, and potential for substantive inhibition eastward into the Great Plains. However, models suggest areas of stronger sub-synoptic ascent may overspread the higher terrain of southern Montana by late Saturday afternoon and evening. In the presence of a deeply mixed boundary layer with modest CAPE, this may become supportive of scattered upscale growing thunderstorm development capable of produce strong downbursts. There appears some potential for consolidating cold pools to support intensifying thunderstorm development, with a continuing risk for strong to severe surface gusts, in better potential boundary-layer instability across southeastern Montana into central North Dakota Saturday evening, before activity weakens in the presence of increasing inhibition. ...Kerr.. 07/24/2025 $$ = = = 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) .