SIOUX CITY | An early morning storm packing winds reaching speeds more than 80 mph caused widespread tree and building damage in at least two Northwest Iowa counties.
The storm struck between 4 and 5:30 a.m. and was the result of a heat burst, National Weather Service meteorologist Alex Ferguson said. The rare atmospheric phenomena is when a thunderstorm begins to die, air sinks quickly and warms up, leading to gusty, damaging winds.
The National Weather Service in Sioux Falls reported a wind gust of 83 mph in Lake Park, Iowa, early Tuesday that caused tree damage in that Dickinson County community.
Dickinson County emergency management coordinator Mike Ehret said storm damage was limited to the western quarter of the county, where winds gusted in excess of 80 mph. Ehret said that by the time the storm moved through the Spirit Lake area, winds were down to 40 mph.
A steel shed two miles west of Lake Park was damaged, and two Lake Park businesses had tin sheets blown off of their roofs.
The O'Brien County Sheriff's Office reported numerous trees down in Sheldon and in the Hartley and Sanborn areas. There were also reports of a couple of gravel roads in rural areas blocked by downed trees.
No injuries have been reported.
MidAmerican Energy worked to restore power to 36 customers in the Ritter area north of Sheldon. High winds blew down power lines, and tree limbs had fallen on other lines.
Sheldon public works director Todd Uhl said the city had some minor power outages after the storm. He said trees and limbs were down in the city, but there was no major damage.
"It's not horrendous by any means," Uhl said.
Hartley city administrator Patty Anderson said school started two hours late this morning as the storm knocked out the city's electric substation. Several trees were blown down in town, Anderson said, and she had reports of at least two cars being struck by falling trees and a trampoline being blown through the side of the owner's house.
Sioux City escaped the brunt of the storm, receiving 0.11 of an inch of rain and wind gusts of 40-50 mph.
Sioux City experienced humid conditions Tuesday with a high in the 80s.
The region was issued a severe thunderstorm watch Tuesday evening until midnight Wednesday. Thunderstorms containing hail and damaging winds are possible before 4 a.m., the weather service said.
More showers and scattered storms are forecast for Wednesday into Thursday morning, with high temperatures cooling into the 70s on Wednesday and 60s on Thursday. Friday also is expected to be cool and rainy with a high of 57 degrees. Ferguson said Sioux City could receive up to 1.50 inches of rain from now through Thursday.