ABERDEEN, S.D.–South Dakota’s first-ever documented tornado in February will go down as an “EF-U” on the Fujita scale, which gives twisters a ranking from EF-0 to EF-5, based on their strength and wind speed.
The U stands for “unknown.”
The tornado touched down Monday afternoon five miles east of Castlewood. It touched down in an open field, and was on the ground for only a minute.
No damage was observed, and without damage, the tornado will be documented as an Enhanced Fujita Scale Unknown or “EF-U.”
