High Wind in Iowa, May 10, 1999

A warm front had moved north into northern Iowa during the day as a cold front approached from the west. At the same time, a very strong upper level low pressure was located over the northern Rockies. Thunderstorms formed in the warm sector over Iowa as an upper level impulse moved through. These storms were mainly restricted to the southeast and south central parts of the state. They moved north during the late afternoon and early evening hours. Though the storms themselves were not severe, they were quite intense and produced gusty winds and hail up to one half inch in size. The storms began to weaken as sunset approached. During the very late afternoon and early evening hours strong winds developed to the west of the thunderstorm area. These were likely either the result of the storms collapsing and drawing higher momentum air toward the surface or by a gravity wave set off by the stronger cluster of storms. High winds of 50 to 60 MPH were common over much of the central and north central parts of the state into the early evening hours. Damage was spotty, however there was scattered tree damage and some outbuilding damage caused by the winds. The strongest winds occurred on a farm near Algona. Winds of at least 70 MPH caused significant damage to buildings and grain bins on a farm there. A semi tractor-trailer rig was blown of f of Iowa Highway 3 in Humboldt County. The driver received minor injuries and damage was set at about $15,000.