Radar Update: Thunderstorms Developing in Southeast South Dakota – 9:30 PM Monday (5/18)

South Dakota Thunderstorms Bring Severe Weather Risks as Storms Develop in Southeast Region

A radar update from Monday, May 18, 2026, indicated the formation of strong thunderstorms in far southeastern South Dakota, with meteorologists warning of potential hail up to half-dollar size as the system continued to organize. The National Weather Service (NWS) has not yet issued formal severe weather advisories for the region, but local officials are advising residents to remain alert as the storms progress.

Storm Development and Forecasted Impacts

According to verified radar data from the NWS, thunderstorms began developing around 3:51 PM local time near the southeastern corner of South Dakota, near the intersection of Charles Mix and Clark counties. The system showed signs of intensification, with potential for isolated severe weather, including damaging winds and large hail. While no tornado warnings have been issued at this time, meteorologists are monitoring the storm cells for rapid changes in structure.

Residents in the affected areas, including the towns of Murdo, Mitchell and nearby rural communities, have been advised to secure loose outdoor items, seek shelter if thunder is heard, and avoid driving through flooded roadways. The NWS typically issues severe thunderstorm warnings when storms produce hail measuring at least one inch in diameter or winds exceeding 58 mph, though no such warnings have been confirmed for this event as of the latest radar update.

Preparedness and Safety Measures

Local emergency management agencies have urged residents to review severe weather preparedness plans. This includes having an emergency kit on hand, identifying safe shelter locations, and staying informed through local weather alerts. The NWS encourages the public to use multiple sources for weather updates, including NOAA Weather Radio, mobile weather apps, and official NWS websites.

No reports of injuries, property damage, or significant disruptions have been confirmed at this time. However, as the storm system continues to move, conditions may deteriorate rapidly. Authorities are advising caution, particularly for those in low-lying or flood-prone areas.

Next Steps and Monitoring

The NWS will continue to provide updates as the storm system evolves. Residents are encouraged to remain vigilant and follow guidance from local officials. For the latest information, the public can visit the NWS Sioux Falls or NWS Aberdeen websites, or tune into local radio stations for emergency broadcasts.

If severe weather conditions worsen, additional advisories will be issued. Until then, preparedness remains the top priority for affected communities.