There is a moderate risk of severe weather for southwest Minnesota and adjacent areas of South Dakota and Iowa for late this afternoon and tonight. The primary severe weather threat will be damaging winds during the evening although an isolated tornado is possible late this afternoon and early this evening.
A strong cold front will move into eastern South Dakota late this afternoon. Scattered thunderstorms will begin to develop along the front by mid afternoon from northeast South Dakota into south central South Dakota. Initially, these storms will have the potential to produce hail up to half-dollar size and wind gusts to 60 mph. As the storms move south and east toward Brookings and Marshall, there will also be a threat of hail up to golf ball size and isolated tornadoes early this evening. As the evening progresses, the storms are expected to form into a squall line over southern Minnesota and far eastern South Dakota and begin to accelerate to the southeast. While the threat for hail will diminish, the threat for damaging winds will increase. There is the potential for wind gusts in excess of 75 mph over portions of southwest Minnesota, far eastern South Dakota and into northwest Iowa. While storms may continue to develop to the southwest toward Yankton, and Sioux City after sunset, the threat for severe weather is not as great although quarter size hail and wind gusts to 60 mph will be possible in these areas overnight.
If you are planning any type of outdoor activity, including camping, you need to be prepared to take shelter should severe thunderstorms develop later this afternoon and overnight. Be sure to monitor NOAA weather radio or local media for the latest on this severe weather situation and for any watches or warnings that may be issued across the area later today and tonight.
Finally, in addition to the threat of severe weather, dangerous heat and humidity can be expected from the Missouri Valley into portions of northwest Iowa where the heat index is expected to exceed 105 degrees this afternoon. Stay cool by remaining in air conditioned places or if you do go outdoors, be sure to drink plenty of non-alcoholic beverages such as water to keep yourself hydrated.