OMAHA — An increased risk for severe weather has been added across the Middle and Lower Missouri Valley for the remainder of Sunday, September 6, with a Slight Risk (Level 2 of 5) now in place over a corridor stretching from Sioux Falls through Omaha and Kansas City, as organized storm clusters and supercells are expected to develop through the afternoon and into the evening hours.
The severe weather outlook, updated at 4:05 p.m. ET Sunday, identifies damaging wind gusts and severe hail as the primary hazards for the remainder of the day, with a broader Marginal Risk zone surrounding the Slight Risk corridor and extending from the Dakotas through Texas and into the Southeast.
Breaking Down Sunday’s Severe Weather Zones
- Slight Risk (Level 2 of 5): A corridor from near Sioux Falls through Omaha and Kansas City, the day’s maximum risk category
- Marginal Risk (Level 1): Surrounding areas including Des Moines, Wichita, Oklahoma City, Dallas, Memphis and stretching into Alabama and Mississippi
- General thunderstorm potential: A much broader area covering the Upper Midwest and stretching into the Ohio Valley
- Primary hazards: Damaging wind gusts and severe hail
- Storm type: A mix of organized storm clusters and supercells
- Timing: Developing through the remainder of the afternoon and into the evening
- Issued: 20:05 UTC Sunday, September 6
The upgrade to a Slight Risk specifically over the Omaha and Kansas City corridor reflects growing forecaster confidence that this area faces a more organized and higher-end severe threat compared to the broader Marginal Risk zone surrounding it, where storms remain possible but with lower expected coverage or intensity.
Why Supercells Are Expected in This Corridor
The outlook specifically calls for a mix of organized storm clusters and supercells, rather than simply scattered thunderstorms, within the Slight Risk zone. Supercells are the most organized and potentially dangerous form of thunderstorm, capable of sustaining rotation for extended periods and producing the most significant hail and wind threats, and occasionally tornadoes, compared to more disorganized storm modes.
The narrow, elongated shape of the Slight Risk area, running roughly north-south through eastern Nebraska and western Iowa into the Kansas City area, suggests forecasters have identified a specific corridor where atmospheric ingredients, likely a combination of instability, wind shear, and a triggering mechanism such as a front or dryline, are most favorably aligned for these more intense storm types to develop.
Omaha and Kansas City Face the Sharpest Threat
With both major metro areas falling directly within the Slight Risk zone, residents in and around Omaha and Kansas City should prepare for the possibility of damaging, fast-moving storms capable of producing significant wind gusts and large hail as the afternoon transitions into evening. The relatively narrow width of the highest-risk corridor means that while these two cities face the greatest concern, the exact storms that develop could still shift somewhat within that zone as the event unfolds…