National Weather Service rates tornadoes from Johnston, Greenfield

A map of tornado reports from the outbreak in Iowa on Tuesday, May 21. A total of 21 triangles indicate possible tornadoes from Red Oak to Nevada.

The National Weather Service in Des Moines confirmed at least two tornadoes following the rounds of severe weather on Tuesday. More reports are expected.

Adair County: Greenfield, Iowa tornado was at least an EF3

The tornado that swept across Greenfield, Iowa on Tuesday afternoon was at least an EF3 tornado

Additional damage assessments will continue over the next several days and results are subject to change, the NWS said in a social media post. It has not yet provided an exact path for the tornado.

Polk and Story counties: EF2 tornado tracked 41 miles from Johnston through Nevada to Zearing

A National Weather Service survey team working on the north side of the Des Moines metro and into Story County, confirmed one tornado as of Wednesday afternoon.

The team confirmed an EF2-rated tornado touched down and traveled from Johnston to Zearing between 4:30 and 5 p.m. Tuesday.

Wind speed is estimated to have reached up to 135 miles per hour. The tornado traveled approximately 41 miles. There are two recorded injuries, according to the post.

The tornado touched down near Johnston High School, causing "extensive" damage that canceled classes for Wednesday.

Iowa Department of Transportation cameras also captured the tornado crossing U.S. Highway 30 near Nevada. The camera showed a stop semitrailer being pushed over as the tornado and debris moved across the road shortly before 5 p.m. on Tuesday.

The semi driver did not report any injuries, Iowa State Patrol Sgt. Alex Dinkla told the Register on Wednesday.

How were other Iowa tornadoes from Tuesday rated?

Tornadoes can't be officially confirmed until the National Weather Service can send crews out to conduct surveys. On social media, the Des Moines office said three survey teams will be in the field on Wednesday. The National Weather Service in Omaha is also sending teams into southwest Iowa to complete surveys.

Unofficial reports from trained weather spotters throughout Tuesday included: A cluster of sightings in southwest Iowa in Cromwell, Prescott, Corning, Carbon, Red Oak and Villisca. Greenfield in southwest Iowa appeared to be a particularly hard hit. In central Iowa there were unconfirmed reports in Nevada, rural Story County and southeast of Polk City.

What is an EF3 tornado?

EF3 tornados have wind gusts of at least 136 mph, according to NWS' website. The EF scale is a set of wind estimates, not measurements, based on damage.

EF ratings begin a 0, with wind gusts of 65 to 85 mph. The highest rating a tornado can have is EF5, with wind gusts of 200 mph or more.

Has Iowa ever had an EF5 tornado?

The 16-year anniversary of the last EF5 tornado in Iowa is coming up this weekend, on May 25.

In 2008, the community of Parkersburg was hit by an EF5 tornado that was the second-deadliest tornado recorded in Iowa history. Nine people died and wind gusts were up to 205 mph, causing more $100 million dollars in damage.

Victoria Reyna-Rodriguez is a general assignment reporter for the Register. Reach her at or follow her on Twitter @VictoriaReynaR.

This article originally appeared on Des Moines Register: Two tornadoes confirmed in Iowa: EF3 in Greenfield, EF2 in Johnston