EL RENO, Okla. — The National Weather Service says it's officially rating a deadly tornado that struck part of Oklahoma on May 31 as an EF3 on the Enhanced Fujita Scale.
Forecasters previously gave the twister a preliminary top-of-the-scale EF5 rating after analysis showed the storm packed 295 mph winds.
The threshold for an EF5 designation is 200 mph, but the National Weather Service says a survey team didn't find damage that would support a rating higher than EF3.
The National Weather Service says the policy for determining EF ratings is based on ground damage surveys, though it says it's exploring whether that policy should change.
More than 20 people died when the tornado hit El Reno, Okla., on May 31.
Two dozen others died when another tornado struck Moore, Okla., on May 20.