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Main Page Reports Data Summary 1st Round

The previous night, the evening of July 13th into the early morning hours of July 14th, a cluster of severe thunderstorms moved through southern North Dakota and into northwest Minnesota. Shortly after daybreak, this cluster or line of storms diminished over Wadena County while a second area of thunderstorms rapidly intensified just ahead of that in southwest Cass County. These new thunderstorms formed quickly into a squall line by 8 AM and then proceeded to push across the southern half of the NWS Duluth County Warning Area over the next 4 hours.

The squall line exhibited two significant bowed segments, and both of these "bow echoes" exhibited an area of enhanced wind velocities as sampled by the doppler radar at the NWS Duluth. Those areas are highlighted (by approximation) with light blue shading on the graphic above. Here is the definition of a bow echo from the NWS Glossary:

A radar echo which is linear but bent outward in a bow shape. Damaging straight-line winds often occur near the "crest" or center of a bow echo.

The curved radar echoes in these types of storms often form when strong downburst winds develop, accelerating the gust front (and therefore the leading edge of the storm) forward, creating a bowed shape. Bow echoes are commonly associated with significant straight-line wind damage, sometimes equivalent to damage in a weak tornado, but this is not an absolute rule. One of the more famous blowdowns in the Northland was associated with a bow echo on July 4, 1999. Below is an animation of the evolution of the storms on July 14.

Hayward Area

A damage survey of the Hayward, Wisconsin area was conducted on July 22nd - about a week after the event. The survey revealed a swath of non-tornadic thunderstorm wind damage from far eastern Washburn County (about 4.8 miles west of Hayward) east-northeast to the Round Lake area (about 8 miles ENE of Hayward). Below is a color-coded map of the swaths of wind damage found on that survey.

Damage was first evident along Hayward Rd. about 1.6 miles east of the Washburn-Sawyer County border. A few trees and some large branches were downed in this area, along with spots along Chippanazie Rd. where the swath intercepted the road. The survey team was unable to access the area north of County Hill Road in far western Sawyer County due to a lack of roads. This forested area is the Kissick Swamp State Wildlife Management Area.

The swath of wind damage was then picked up crossing Gorud Rd. where some trees were blown down along about a 0.2 to 0.3 mile long stretch of the north-south road. This was where the area of enhanced wind damage started, with a few trees observed to have been uprooted or even snapped. Similar damage was observed on several residential streets to the west of the Hayward Golf and Tennis Club - especially along Wittwer Rd., Deer Lane, and Eagle Tree Rd. Winds in these areas from Gorud Rd. to the northwest corner of the golf course probably increased to about 70-85 mph based on observed damage.

Pictures from Deer Lane (left 2 pictures) and Gorud Rd. (right 2 pictures)
All pictures were taken by NWS Duluth Storm Survey team

The intensity of the damage increased again on the northern fringes of the golf course. A stand of large trees was completely demolished, with some of the trees snapped off about 6-10 feet above their bases. The snapped trees appeared to be primarily of evergreen variety, with other evergreens and some deciduous trees uprooted.

Pictures from near the Golf Course
From left to right, and then top to bottom, the first 6 pictures are courtesy of Terrell Boetcher at the Sawyer County Record newspaper (used with permission)

Significant wind damage continued east into a small subdivision just east of the golf course. Some homes received some light damage, with some shingles and siding removed by the severe winds. One home had a detached garage collapse, which was likely due in part to an open door on the west-facing wall. This home also had part of the roof deck removed, and nearby willow trees were badly damaged. Similar garages in the neighborhood sustained no visible damage.

Pictures from Homes East of Golf Course
All pictures were taken by NWS Duluth Storm Survey team

Slightly further east from that, the Evergreen Professional Building at Company Lake Rd. and Nyman Ave. received substantial tree damage, with large trees more than a foot in diameter uprooted and blown into the building and even onto a vehicle in the parking lot. Many of these trees were large evergreens. Just south of that building, three other houses had some shingles removed, and several other large evergreen trees along Company Lake Rd. were snapped.

Pictures from Near Evergreen Professional Building
First 3 pictures are courtesy of Terrell Boetcher at the Sawyer County Record newspaper (used with permission). Last picture was taken by NWS Duluth Storm Survey team

The damage was probably at its most intense near the intersection of Hospital Road and Highway 27. In a small park just west of the Highway, every tree was either uprooted or snapped. North of Hospital Road there was a large stand of red pine trees that was completely demolished with all trees either snapped off about 6-10 feet above the base, or uprooted. South of Hospital Road, the forest was more of a mixed variety, with about 50-60% of the trees uprooted or snapped. These large trees (some with trunks over 2 feet in diameter) may have fallen into Hospital Road, as some appeared to have been cut and pushed to the side of the road. The very intense tree damage, in which all trees were either snapped or uprooted, continued about 0.4 miles east from Highway 27 along Hospital Road.

Pictures from along Hospital Road
All pictures were taken by NWS Duluth Storm Survey team

Tree damage was still noted along Hospital Road all the way to Highway 63, gradually becoming more sporadic towards the Hayward Airport, where wind speeds (estimated based on damage) probably decreased back into the 70-85 mph range. Some evergreen trees were still observed to be uprooted or snapped as far east as the airport. The strong winds also damaged the tail of an aircraft at the airport. The damage fanned out over a much broader area to the east hitting a forested area bounded by Highway 63, Highway 77, and Mosquito Brook Rd. In that area, there were scattered places where some trees were still uprooted or snapped. The most concentrated area appeared to be along the east-west bend in Mosquito Brook Rd. Damage abated towards Highway 77 at the north tip of Round Lake, and the last observed damage was to several exposed birch trees that were pushed to be leaning over.

Pictures from just north of the Hayward Airport
All pictures were taken by NWS Duluth Storm Survey team

The damage was most likely caused by non-tornadic thunderstorm winds based on how most trees and debris were blown to the east and northeast, and how the damage swath started very narrow and gradually fanned out in the area east of the airport. The total length of the swath of enhanced wind damage was about 13 miles long. Winds probably peaked around 95-100 mph in the area near the intersection of Hospital Rd. and Highway 27 based on the extensive and total damage to heavily forested areas. Such wind speeds and damage are equivalent to an EF-1 tornado on the Enhanced Fujita Scale. The area of most intense damage was only about 1 mile long, and the swath in that area was about 1/4 to 1/2 mile wide.

Below are a series of radar images from around the time that Hayward was hit (approximately 10:40 AM). Each image is a 2-panel, with the left panel being the radar reflectivity - something that people are accustomed to looking to when they see radar images. The right panel is what the radar is sampling for wind velocities. In this case, salmon/pink colors tend to show areas of at least 50 knots (58 mph) of wind, and orange colors suggest values closer to 60 knots (69 mph). It's important to remember that, because of the curvature of the Earth, these values are not necessarily indicative of what is occurring at the surface. In this case, the radar beam is hitting the storm about 6000 feet above the ground. is the U.S. government's official web portal to all federal, state and local government web resources and services.