ACUS01 KWNS 201231 SWODY1 SPC AC 201230 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Wed Aug 20 2025 Valid 201300Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS/DEEP SOUTH AND NORTHERN PLAINS... ...SUMMARY... Scattered thunderstorms from Texas across the Lower Mississippi Valley and Gulf Coast states may pose a risk for localized damaging wind gusts this afternoon and evening. Isolated severe thunderstorms may also occur across eastern Montana and northern North Dakota. ...Texas to Lower Mississippi Valley/Gulf Coast States... A convectively augmented effective front will continue to progress southward, southward-shifting the potential for microburst-related wind damage regionally. Diurnal heating of a moist boundary layer will result in a moderately to strongly unstable and weakly capped airmass by afternoon, with the strongest buoyancy (2500+ J/kg MLCAPE) expected across central/east Texas east-northeastward to Mississippi/western Alabama/southern Tennessee. Some small-scale clusters may evolve, but weak vertical shear will otherwise tend to keep the overall pulse-type damaging wind potential very isolated. ...Northern Plains... The region will be influenced by late-day/nighttime height falls as a shortwave trough emerges eastward from the Canadian Rockies, with an eastward-advancing cold front moving across eastern Montana into North Dakota tonight. A narrow corridor of moderate to large buoyancy is expected along/ahead of the surface cold front, and near a pre-frontal surface trough. Beneath a plume of warm elevated mixed-layer air, mid/upper-level support for the initiation of boundary-layer based thunderstorm development is forecast to generally remain north of the international border. One exception may be in the post-frontal environment across eastern Montana, the environment would be conducive to a few severe storms capable of hail/wind. While the risk for severe thunderstorms appears largely conditional into North Dakota where stronger destabilization is expected, isolated deeper convective development is plausible across northwestern North Dakota in proximity to the surface low/front late this afternoon, and more so this evening. Should this occur, forecast soundings indicate the environment would support isolated supercell development and related severe-weather risks. ..Guyer/Marsh.. 08/20/2025 $$