Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 15 2025 16:33:40 ACUS01 KWNS 151632 SWODY1 SPC AC 151630 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Aug 15 2025 Valid 151630Z - 161200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND TONIGHT FROM PARTS OF SOUTH DAKOTA INTO THE UPPER MIDWEST... ....SUMMARY... Scattered strong to severe storms are likely today and tonight over parts of the northern Plains and Upper Mississippi Valley. ....MN/IA/WI... Recent satellite imagery shows a pair of convectively generated vorticity maxima moving across the northern/central Plains, with the northernmost vorticity max over the eastern ND/SD border and the southernmost vorticity max over north-central NE. Showers and thunderstorms have persisted near these features over the last several hours, but the strongest cells in both of these clusters have recently shown a weakening trend. A moist and buoyant airmass, characterized by dewpoints in the upper 60s/low 70s, exists downstream and redevelopment is possible ahead of both of these vorticity maxima. How that redevelopment evolves is uncertain, with recent guidance offering varied solutions regarding overall coverage and evolution. Redevelopment appears most probable with the southern vorticity maxima, given the ample moist and buoyancy that exists downstream. This development should grow upscale quickly, with the resulting convective cluster then tracking southeastward. Recent guidance continues to trend farther south, so the wind probabilities were extended southward to cover this potential. Damaging gusts appear like the most likely threat through the evening. Current progression of the northern vorticity maximum takes it into a less buoyant airmass across central MN and northern WI, and redevelopment along/ahead of this disturbance appears less likely. Depending on the strength of the IA cluster, additional development is possible in its wake amid a strengthening low-level jet and associated warm-air advection over its outflow. Steep mid-level lapse rates should still be in place, supporting strong updrafts and large hail with these elevated storms. Lastly, a decaying convective line may reach the southwestern MN/northwestern IA vicinity late in the period. Given the potential for preceding storms, the amount of buoyancy that will still be in place remains is uncertain. However, if thunderstorm coverage is low or most storms develop farther east, enough buoyancy could remain to support strong updrafts capable of damaging gusts and/or hail within the convective line or any preceding more cellular storms. ...NE/SD this afternoon through tonight... Strong heating and ample mid-level moisture will result in scattered high-based thunderstorm development across eastern WY and western NE/SD by late afternoon. Isolated hail and strong gusts are possible with this initial activity. This activity will then track east-northeastward through the early evening into a progressively more moist and unstable air mass across NE and SD. The combination of improving thermodynamic environment and an intensifying nocturnal low-level jet will likely aid in thunderstorm intensification and upscale growth through the evening across northern NE and central SD. Guidance continues to vary significantly with the strength of this MCS, but general consensus would suggest the threat for strong to severe gusts will persist across SD tonight. There is at least a low probability for the development of a well-organized MCS that could produce significant severe gusts. However, that probability is currently too low to introduce an unconditional sig wind area. ....TX Coastal Plain into the Hill Country and Southeast TX... A maturing tropical disturbance is near south TX, with associated outflow currently spreading northward across the TX Coastal Plain. Limited lightning has been noted with in the short-lived cores that have been developing along this outflow. This process of brief intensification along this outflow is expected throughout the day, with an overall increase in thunderstorm coverage anticipated. A modest increase in low to mid-level flow is expected along the eastern periphery of this system, spreading northward into central and southeast TX. Even so, shear will remain weak, with a disorganized multicellular pulse storm mode anticipated. Given the very moist profiles (i.e. PW values over 2"), a few water-loaded downbursts are possible, but should be isolated enough to preclude the need for severe probabilities. ...Mosier/Wendt.. 08/15/2025 $$ = = = 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) .