Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
108 ACUS02 KWNS 121734 SWODY2 SPC AC 121733 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1233 PM CDT Tue May 12 2026 Valid 131200Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTH-CENTRAL MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern High Plains Wednesday afternoon and evening. Severe wind gusts are the primary hazard. ...Northern Rockies and High Plains into northern Utah... A potent mid-level shortwave trough over western OR/WA will move east across the northern Rockies into the northern High Plains as a downstream ridge shifts east into the Upper Midwest by early Thursday morning. An attendant 80-90 kt 500 mb speed max will overspread ID/MT by peak heating as a cold front sweeps east across portions of the northern Rockies into the northern parts of the Great Basin. Forcing for ascent and diurnal destabilization will lead to scattered thunderstorms developing by mid afternoon. Forecast soundings show large surface temperature-dewpoint depressions and inverted-V thermodynamic profiles. Increasing flow through the cloud-bearing layer will result in relatively swift storm motions within pre-conditioned, dry-adiabatic 0-3 km lapse rates. Isolated to scattered storms developing over the higher terrain will move into the lower elevations and increase in coverage as a couple of linear clusters evolve towards early evening across central MT, and to a lesser degree, across eastern ID. The primary risk will be severe gusts (60-80 mph) accompanying the stronger cores and outflow. Farther south, very deeply mixed boundary layers evident in forecast soundings across northern UT into southern ID will favor severe gusts with the stronger cores. ...Ohio Valley/Central Appalachians... An upper-level trough initially over the central Great Lakes will move east-southeastward to the Lower Great Lakes and Mid-Atlantic states vicinity during the period. Strong cyclonically curved, 500-mb flow (50+ kt) will move through the base of the trough. A surface low will move eastward across southwestern Ontario as a cold front advances east-southeastward into the central Appalachians. Ahead of the front, surface dewpoints in the lower to mid 50s F will contribute to weak instability as surface temperatures warm during the day. Increasing low-level convergence near the front will lead to scattered thunderstorm development, with additional storms forming due to topographic forcing in the central Appalachians. Ahead of the front, low to mid-level lapse rates are forecast to steepen by midday/early afternoon, lending the potential for several stronger thunderstorms capable of an isolated risk for wind damage and localized severe gusts. ...TX Panhandle... Despite a 500-mb ridge overhead, very strong boundary layer heating may sufficiently erode convective inhibition and yield a couple of thunderstorms developing near the Caprock (22-00 UTC). Very steep lapse rates will support an isolated risk for hail/wind if sustained storms develop. This activity will likely dissipate by mid evening. ..Smith.. 05/12/2026 $$