Complex sentence: The fourth tornado formed near the unincorporated town of Leota in southwest Minnesota, spawning a "maxi" tornado that stayed on the ground for almost an hour and a half and did substantial damage to the cities of Chandler and Lake Wilson, Minnesota.
Split into simpler sentences: The fourth tornado formed near the town of Leota in southwest Minnesota and spawned a maxi tornado. It was on the ground for almost an hour and a half and did horrendous damage to the towns of Chandler and Lake Wilson, Minnesota.