Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
398 ACUS02 KWNS 121736 SWODY2 SPC AC 121735 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1235 PM CDT Wed Aug 12 2026 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF SOUTHERN/CENTRAL NEVADA...AND FROM THE FRONT RANGE INTO THE MIDDLE OHIO VALLEY... ...SUMMARY... Isolated severe storms are possible on Thursday from the parts of the southern Great Basin, Colorado Front Range, and central High Plains into the Ohio Valley. ...Central Plains into Ohio Valley... Model guidance is uniform in placing early morning convection/MCS in Iowa. This feature will likely track into parts of the Upper Midwest as has been the case the past couple of days. What will be lacking on Thursday will be steep mid-level lapse rates owing to the amount of recent convective overturning. Secondary to that, the morning convection will likely move through and airmass north of the effective surface boundary. Isolated wind damage will be possible, however. There will be strong heating in Missouri with modest southwest flow into the surface boundary. There will be a conditional threat for a supercell or two along the boundary during the afternoon. Forcing will be weak, however, and this scenario is uncertain. As the low-level jet intensifies during the evening, areas of scattered storms will be possible from the central Plains into the Upper Midwest. These storms are likely to be at least slightly elevated. Boundary parallel deep-layer shear will also mean activity will tend to train/interact along the boundary and be only briefly supercellular. Isolated large hail and wind damage would be the main concerns. ...Front Range into central High Plains... Moist upslope flow on the north/northwest side of the surface low in the central Plains will promote moderate to locally strong destabilization within these regions. Deep-layer shear of around 30 kt can be expected along the Front Range. Scattered storms should develop by the afternoon. The strongest of this activity will be capable of large hail and severe wind gusts. Near the Sangre de Cristo/Raton Mesa, additional convection is expected to develop along the surface boundary with strong heating to the south. Severe winds would be the main hazard with this activity as it moves north and east. There is some signal for clustering within some of the CAMs which would promote a locally greater risk in parts of western Kansas. ...Nevada... A broad upper trough along the West Coast will bring modest southwesterly flow across the southern Sierra. Model guidance suggests that a shortwave perturbation will be favorably timed with afternoon heating and help to focus a small cluster of convection moving off of the higher terrain into parts of central/southern Nevada. Low-level lapse rates are expected to be steep, particularly in the lee of the Sierra. Severe wind gusts will be possible with this activity. ...Northeast... A broad upper trough with one or more embedded shortwave troughs will move across the region during the period. A strong mid-level jet will develop into parts of the northern Mid-Atlantic with decreasing mid-level flow to the north and east. While some drying/mixing can be expected, MLCAPE of 500-1000 J/kg is possible given cold temperatures aloft. The core of the mid-level jet will be offset from the larger instability. Furthermore, modest subsidence aloft is apparent in forecast soundings likely due to the region being in between shortwave troughs during the afternoon. Gusty winds and small hail are possible with the strongest storms, but severe potential appears too isolated for probabilities. ...Southeast... A remnant MCV is possible near the southern Appalachians during the morning. Models differ in the overall strength of this feature. The NAM has the most robust circulation, but also weakens it with time. Moderate to strong buoyancy is expected by the afternoon, but shear will remain weak. While a few strong to locally severe wind gusts are possible, confidence in an area of greater concentration/organization remains quite low at present time. ..Wendt.. 08/12/2026 $$