Was the Greenfield tornado the strongest tornado ever? What mobile wind speed data shows.
New data shows that winds in the recent Greenfield, Iowa tornado surpassed 300 mph, marking only the third time that scientists have calculated wind speeds that high within a tornado.
Where did data on Greenfield, Iowa tornado's wind speed come from?
A radar truck, called a Doppler on Wheels or DOW, recorded the storm data. The mobile radar is operated by a research team from the University of Illinois, National Weather Service officials told the Register.
Storm chasers took the readings from multiple angles, offering new findings of the winds and inner dynamics of the storm, according to a news release from the team. The team told NBC News it stationed its radar truck about a mile east of the center of Greenfield, about 300 yards from the edge of the tornado.
Scientists say the Greenfield tornado intensity was rare
“Tornadoes producing this intensity and this kind of damage are rare in the United States. We only get a handful of these each year,” Tony Lyza, a physical scientist at the National Severe Storms Laboratory in Norman, Oklahoma, uninvolved in the research, told NBC.
Multiple vortices swirled within the tornado, NBC reported. For less than a second, the researchers calculated wind speeds of more than 300 mph in a portion of the tornado.
The storm was up to 1,000 feet wide at times, NWS said. But by the time it hit Greenfield, it had narrowed. Scientists aren’t quite sure why that happened, said NBC, but that’s one of the mysteries a DOW could eventually help solve.
What was the Greenfield, Iowa tornado rated?
The tornado that hit Greenfield is officially rated an EF4, the second strongest on the Enhanced Fujita scale. The NWS has previously said that additional analysis is being done and that refinements to its rating are possible.
The scale looks at damages observed to estimate maximum wind speeds. It would take estimated speeds of 200 mph or higher to achieve an EF5 rating.
What are the highest tornado wind speeds recorded by a Doppler on Wheels?
The University of Illinois team calculated wind speeds as high as 309-318 mph with the tornado in Greenfield. It's only the third time speeds have been calculated at more than 300 mph, according to a news release.
Here are the highest speeds, according to the University of Illinois:
El Reno, Oklahoma tornado: Calculations placed the top speeds from the May 31, 2013 tornado at 291-336 mph.
Bridgecreek, Oklahoma tornado: Original calculations from the May 3, 1999 placed wind speeds observed by a DOW at 302 mph. Newer research with improved techniques revised that calculation to 321 mph.
Greenfield, Iowa tornado: The May 21, 2024 tornado has calculated speeds of 309-318 mph
Victoria Reyna-Rodriguez is a general assignment reporter for the Register. Reach her at vreynarodriguez@registermedia.com or follow her on Twitter @VictoriaReynaR.
This article originally appeared on Des Moines Register: Was the Greenfield tornado the strongest tornado? See its wind speeds
