A deadly tornado that tore across southeastern North Dakota this summer has been upgraded to an EF5 with winds topping 200 mph (322 kph), the strongest classification of tornado and the first confirmed on American soil in a dozen years, meteorologists said Monday.

The June 20 twister near the town of Enderlin killed three people and at its largest was 1.05 miles wide (1.7 kilometers), carving a path across the prairie for just over 12 miles (19 kilometers). Meteorologists from the National Weather Service office in Grand Forks estimated the tornado's winds reached 210 mph (338 kph), according to the newly released analysis.

The 1999 Bridge Creek-Moore tornado in Oklahoma holds the record of the strongest winds ever recorded in the U.S. at 321 mph (517 kph).

Since the National Weather Se

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