Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Aug 11 2025 05:42:25 ACUS01 KWNS 110542 SWODY1 SPC AC 110541 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Mon Aug 11 2025 Valid 111200Z - 121200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS AND RED RIVER VALLEY OF THE NORTH... ....SUMMARY... Strong thunderstorms accompanied by at least some risk for severe wind and hail may impact parts of eastern New Mexico into the Texas South Plains, as well as parts of eastern North Dakota into northwestern Minnesota, late this afternoon and evening. ....Synopsis... Late-evening water-vapor imagery depicts an upper trough/vorticity maximum settling into the southern/central High Plains. This feature is expected to stall and weaken over the Plains over the next 24 hours with a gradual abatement of mid-level flow. To the north, a pronounced mid-level wave is apparent over the Canadian Rockies/Prairies. This feature will continue southeastward into the northern Plains and upper Mississippi River Valley through tonight. Strong/severe thunderstorm chances will largely be attendant to these mid-level features. ....Southern High Plains... 05z surface observations across the southern Plains reveal a composite frontal zone/outflow boundary draped from far northeast NM through the TX/OK Panhandles and roughly along the OK/KS border. This boundary will likely be displaced southward as a result of early-morning convection, though precisely where this boundary resides by peak heating is somewhat uncertain. Regardless, thunderstorm development along this boundary is expected by late afternoon/early evening. To the south of this boundary, easterly winds on the northern periphery of a weak surface low over the Permian Basin will maintain an upslope flow regime along the eastern slopes of the Sacramento, Sandia Manzano, and Sangre de Cristo Mountains. Modest westerly mid-level flow atop easterly low-level winds should yield sufficient deep-layer shear for a few organized storms, including a supercell or two. With time, upscale growth and/or merging with additional convection developing along the surface boundary will promote an increased threat for severe gusts through early evening. While convection is expected northeastward along much of the boundary from central OK into adjacent portions of KS/MO, weaker mid-level winds with eastward extent casts doubt on the potential for a robust severe threat (aside from occasional strong wet downbursts). ....Red River Valley of the North... Modest surface cyclogenesis is anticipated across the central Canadian Prairies over the next 24 hours as the mid-level wave approaches the international border. An attendant cold front is forecast to spread across the northern Plains through late afternoon and will impinge on a plume of seasonal low-level moisture. While mid-level lapse rates will remain modest (around 6-7 C/km), adequate buoyancy should be in place for deep convection. 30-40 knot mid-level flow should provide sufficient deep-layer shear for organized storms, though the marginal thermodynamic environment will likely be a modulating factor in overall storm intensity. Strong frontal forcing should promote upscale growth through the evening hours with an associated threat for damaging/severe winds. ...Moore/Darrow.. 08/11/2025 $$ = = = 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) .