Wind Storms can and do occur in all months of the year, however, the most severe windstorms usually occur during severe thunderstorms in the warm months.
The most common windstorms to affect St. Louis County are straight-line winds or downbursts associated with strong thunderstorms. A downburst is a severe localized downdraft from a thunderstorm or a rain shower. This outflow of cool or colder air can create damaging winds at or near the surface. Winds up to 130 M.P.H. have been reported in the strongest thunderstorms. Downburst winds can cause as much damage as a small tornado and are frequently confused with tornadoes because of the extensive damage they cause. As these downburst winds spread out they are often referred to as straight-line winds. They can cause major structural and tree damage over a relatively large area. They can also create a hazard for small watercraft on Lake Superior.
Winds of greater than 60 M.P.H. are also associated with intense winter, spring, and fall low-pressure systems. These can also inflict damage to buildings and in some cases overturn high profile vehicles. This type of windstorm can particularly impact residents living on the shore of Lake Superior and watercraft on Lake Superior and damage shoreland structures such as docks and marinas. Most of the Arrowhead Region of Minnesota, including St. Louis County, is located in Wind Zone II. Wind zone I is designated as a moderate wind speed area while wind zone II is a high wind speed area. Buildings within this Zone II should be able to withstand wind speeds of up to 160 M.P.H.
Summer Storm History
The most recent large-scale summer storm that affected St. Louis County was the July 4th, 1999 windstorm, which caused significant damage in the northern part of St. Louis County to the forestlands. This event resulted in a Presidential Disaster Declaration for St. Louis County. Much of the blow down was located in the Boundary Waters Canoe Area Wilderness (BWCAW) and the Superior National Forest (SNF) in the northeast portion of St. Louis County. Other areas that have experienced straight-line winds include the Meadowlands area in August of 1995 and the Brimson are in July and August of 2002.