FLOYD COUNTY, Iowa - A tornado Wednesday near the Avenue of the Saints in Floyd County was classified as an EF-1 with a max wind speed of 90 miles per hour.
The National Weather Service in La Crosse said the length of the tornado was 11 miles and went from 5:35 p.m. to 6 p.m.
It was located three miles north of Rockford to five miles northwest of Charles City.
A second tornado near Oelwein was an EF-0 with a max wind speed of 70 miles per hour.
The NWS in La Crosse WI conducted a damage survey today and documented two tornado tracks in northeast Iowa near Oelwein and Charles City, respectively. Full details can be found here: https://t.co/lDCYsDL0Ma pic.twitter.com/O7YXI3HNy2
— NWS La Crosse (@NWSLaCrosse) July 15, 2021
Following a day that was forecasted for severe weather, regions of North Iowa are cleaning up after what is estimated to be multiple confirmed tornadoes that developed between Cerro Gordo and Floyd counties.
Just after 3 PM CDT the Storm Prediction Center in Norman, Oklahoma issued a mesoscale discussion indicating a 95% probability of a Tornado Watch being issued across Central and North Iowa. Roughly thirty minutes later, the watch was issued as the forecast called for convective initiation to develop just after 4 PM CDT along the Iowa and Nebraska border.
As expected, storms began to show up on the Des Moines, IA radar site. Quickly, tornadic supercells developed across Central Iowa. Leading up to Wednesday, the big question across the meteorology community was "When will the clearing occur and who will see it?" This meaning that during the break between waves one and two of Wednesdays severe weather threat, where would the clouds dissipate, and sun return.
As showers continued to suppress the severe threat for most of Southern Minnesota, cloud coverage soon became pockets of sunshine and blue skies across North and Central Iowa. This allowed for CAPE (Convective Available Potential Energy) to surge northward, destabilizing the atmosphere. At the same time, with dew points in the mid 60s, shear, and Storm Relative Helicity (SRH) great enough to aid in the development of tornadic genesis, it was only a matter of time before warnings would come across a NOAA Weather Radio, and mobile devices.
As Central Iowa saw the tornadic genesis unfold early in the tornado watch period (which was set to expire at 9 PM CDT), it wouldn't be until 5 PM CDT that North Iowa would become a part of the action. Cells soon began to show up west of Garner, IA as the atmosphere around it became more unstable with time. While this occurred, a cell soon developed to the South of Mason City, IA. It would be this cell that would spawn the tornado near Nora Springs, IA as it traveled SSE, coming close to Highway 18, likely crossing it.
As the storm evolved, a tornado warning was issued as a pronounced couplet formed on the radars velocity scan. It was here the National Weather Service (NWS) in La Crosse, WI issued the tornado warning. Sirens quickly sounded across Rockford, Nora Springs and Rudd. Moments later images of the stove pipe tornado surfaced across social media platforms. The once semi-rain wrapped tornado was on the ground and in a region of clearing, away from rain. This made it visible to viewers across Rockford, IA.
After its initiation, the tornado became cyclic in nature as the velocity couplet would decrease in intensity, then quickly resurface with each radar pass. This would continue on for around forty to fifty minutes as the cell continued a path now towards Charles City, IA before falling apart soon after.
Behind this cell, another cell south of Garner, IA was also issued a tornado warning. That warning was discontinued at its set time seen in the warning discussion.
Today, the NWS will be sending a crew to conduct damage evaluations of the region impacted, as well as other observations before coming to a conclusion on the appropriate scaled intensity of the tornadoes spotted. A report is expected to be released following the crews analysis.