Damage surveyors have concluded that the massive tornado that left six people dead in and around the town of Winterset, Iowa, produced maximum winds of 170 mph.
The extreme wind speeds make it an EF-4 tornado, which is the second strongest on the Enhanced Fujita Scale, which measures the strength of a tornado based on the damage it causes. EF-4 tornadoes have wind speeds anywhere from 166 to 200 mph and are known to level well-built houses, throw cars and turn large debris into missiles.
Six people were killed and five others were injured. Among the dead are a 37-year-old man, two of his children, ages 5 and 2, and his mother-in-law. A seventh victim was killed in a separate EF-3 tornado that ripped through Red Hawk State Park.
The twister touched down just southwest of Winterset at 4:26 p.m. Saturday and continued for 69.5 miles before lifting around 6:01 p.m. just north of Newton, according to the National Weather Service.
It had a maximum width of 800 yards, which made it nearly a half-mile-wide tornado.
Here's another view of the tornado's track, with different colored markers identifying what type of damage was seen in specific areas. Blue is EF-0, green is EF-1, yellow is EF-2, orange is EF-3 and red signifies EF-4 damage, which was isolated to an area just southwest of Winterset.
Here's the radar loop from the National Weather Service in Des Moines showing all three supercells that spawned strong tornadoes during Saturday's outbreak.
The EF-4 Winterset tornado is the first of that rating in Iowa since 2013, and the nearly 70 miles it stayed on the ground is the second longest tornado in Iowa since a 1984 tornado traveled an incredible 117 miles across southern Iowa.