A severe thunderstorm watch has been issued for northwest Iowa until 5am CDT. Primary threats include scattered large hail and isolated very large hail events to 2 inches in diameter possible. Scattered damaging wind gusts to 70-mph possible.
A cluster of thunderstorms over central South Dakota will continue to track east/southeast into the watch area overnight. Other storms are also expected to form out ahead of the initial cluster. Large hail and damaging winds will be possible with all of this activity.