Multiple funnel clouds form over Iowa Sunday
Video shows two of the funnels spinning simultaneously close together.
Video shows two of the funnels spinning simultaneously close together.
Video shows two of the funnels spinning simultaneously close together.
Multiple funnel clouds developed Sunday across Iowa, including a pair of simultaneous funnels in Sac County.
Video shared with vlog by Bill Brotherton shows two well defined funnels rotating close together near Wall Lake around 11:30 a.m.
Radar data showed a small shower developing along the Sac/Carroll county line at the time.
Short-lived funnel clouds will often form in situations like this.
A low-pressure center called a mesoscale convective vortex was crossing northwest Iowa Sunday morning. These often help generate showers and thunderstorms.
In the same area was a boundary stretching from Minnesota down toward Omaha/Council Bluffs. Light winds blowing different directions along boundaries often lead to areas of increased vorticity, or spin, in the air.
These weak circulations can sometimes get lifted by the updraft of a developing storm, shower, or even just a cloud.
RAW VIDEO: Multiple funnel clouds form over Iowa Sunday
This rising motion will stretch the circulation into a narrow, faster spinning tube of air which appears as a funnel at the base of the clouds.
These funnels don't usually last long and rarely touch down as tornadoes.
Other funnel clouds were spotted later in the day in Hamilton and Marshall counties.