Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 05 2025 09:00:15 ACUS48 KWNS 050900 SWOD48 SPC AC 050858 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0358 AM CDT Tue Aug 05 2025 Valid 081200Z - 131200Z ....DISCUSSION... ....Friday/Day 4 to Sunday/Day 6... On Friday, a mid-level trough and an associated speed max is forecast to move into the northern Plains. At the surface, a moist airmass will be in place over much of the northern Plains, where surface dewpoints are likely to be in the lower to mid 70s F. As surface temperatures warm during the day, moderate to strong instability is expected to develop. Along the northwestern edge of this unstable airmass, thunderstorms should form in parts of central and eastern North Dakota. Convective coverage is forecast to expand southward into South Dakota during the evening. Moderate to strong deep-layer shear associated with the speed max will be favorable for a severe threat during the afternoon and evening. Supercells with large hail, severe wind gusts and a tornado threat will be possible. On Saturday, the mid-level trough and associated cold front are forecast to move eastward into the upper Mississippi and mid Missouri Valleys. Thunderstorms are forecast to be ongoing along and near the front during the morning, with additional thunderstorm development taking place further southeast in the afternoon. Moderate instability and deep-layer shear is forecast across much of the region, suggesting that a severe threat will again be possible. There is some uncertainty as to how much the airmass will be negatively affected by the morning convection. Also, model forecasts suggest that the greatest convective potential will be during the overnight period on Saturday. For this reason, will not add a threat area for Saturday at this time. On Sunday, a mid-level trough is forecast to move across the north-central U.S., being positioned from the northern Plains to the central Rockies by afternoon. A moderately unstable airmass is forecast further to the east, from the upper Mississippi Valley southward into the mid Missouri Valley. An isolated severe threat will be possible Sunday afternoon along and near the instability axis. However, the mid-level trough is forecast to remain well to the west of the instability axis, which should limit large-scale ascent over the unstable airmass, helping to keep any severe threat isolated. ....Monday/Day 7 and Tuesday/Day 8... A low-amplitude mid-level trough is forecast to move into the upper Mississippi Valley on Monday, and into the western Great Lakes on Tuesday. Further southwest, a mid-level low is forecast across the central Plains. Thunderstorms will be possible on Monday and Tuesday afternoon, along the northern edge of a moist airmass from the central Plains northeastward to the Great Lakes. Model forecasts suggest that deep-layer shear will be relatively weak. Although convective coverage and any associated severe threat will likely remain isolated, a few marginally severe storms could occur in areas that heat up the most. ...Broyles.. 08/05/2025 = = = 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) .