The Wisconsin tornado count from last weekend is now at eight, following National Weather Service surveys that completed on Monday afternoon.
The eight tornadoes came on Saturday as part of a severe weather system that dumped rain across the state and left over 10,000 without power for a time. The severe weather also closed roads due to downed powerlines and dumped more than 5 inches of rain in some areas.
“The event that we had was kind of complicated. There were some embedded supercells in the main line,” said Nate Falkinham, a local meteorologist at the Milwaukee office of the NWS, on the weekend weather. “I wouldn’t say it was typically normal, but it’s not unheard of.”
Here’s where the tornadoes occurred and how strong they were, according to NWS reports:
Lafayette County Tornado
A minor tornado occurred in western Lafayette County. That tornado was an EF-0 and had a path length of 5.6 miles, was 75 yards wide and lasted about 10 minutes, from 6:02 p.m. to 6:12 p.m.
The tornado reached peak wind speeds of about 80 miles per hour and NWS surveyors noted sheet metal damage to a barn roof and tree damage.
Argyle Tornado
Among the most significant tornadoes from Saturday was one the NWS is calling the Argyle Tornado, which demolished the Argyle-Apple Grove Lutheran Church. NWS surveyors rated this tornado an EF-2 and it had a path length of 6.94 miles, was 500 yards wide and lasted about 12 minutes, from 6:36 p.m. to 6:48 p.m.
The tornado’s peak wind speeds reached 135 mph and damaged barns, in addition to the church.
Dane County – Marshall Tornado
An EF-1 tornado developed south of Marshall in Dane County. The tornado had a path length of 4.6 miles, was 300 yards wide and lasted about five minutes, from about 7:10 to 7:15 p.m.
The tornado reached peak wind speeds of around 105 mph. It damaged farms and a large area of trees, before it ended on the south side of Waterloo.
Jefferson County Tornado
Another EF-1 tornado developed in Jefferson County, west of Watertown. The tornado had a path length of 2.07 miles, was 150 yards wide and lasted about five minutes, from 7:30 to 7:35 p.m.
The tornado’s estimated peak winds were about 105 mph and it caused “significant” damage to a farm.
Janesville Tornado
Along with the Argyle Tornado, an EF-2 tornado in Janesville was the most significant of the day’s storms. The tornado’s path length was 6.21 miles, it was 700 yards wide and lasted for 11 minutes, around 7:42 p.m. to 7:53 p.m.
The tornado reached peak wind speeds of 115 mph and cause damage to the southern inside of Janesville. Most of the damage was at an EF-1 level, otherwise, according to the NWS report.
Williams Bay Tornado
An EF-1 tornado occurred in Walworth County, near Delavan Lake and Williams Bay. The tornado had a path length of 6.07 miles, was 150 yards wide and lasted for about eight minutes, from 8:22 p.m. to 8:30 p.m.
The tornado had peak wind speeds of 105 mph and caused homes to lose portions or most of their rooftops in a subdivision northwest of Williams Bay.
Geneva Lake Tornado
Another EF-1 tornado developed south of Geneva Lake and moved northeast across the lake before lifting south of Lake Como. The tornado had a path length of 5.31 miles, was about 100 yards wide and lasted for seven minutes, from 8:22 p.m. to 8:29 p.m.
The tornado reached an estimated 100 mph peak wind speed and damaged trees, piers and caused other structural damage.
Grant County Tornado
Another tornado occurred outside of the Milwaukee area, according to the La Crosse office of the NWS.
That was an EF-0 tornado and reached peak winds 70 mph, its path length was .16 miles and 40 yards wide, said Jonathan Maylor, a meteorologist at the La Crosse NWS.
The tornado caused tree damage near the intersection of Highway O and North Lane, according to the storm report. It occurred in Grant County, near the small village of Tennyson, at about 5:37 p.m.
How tornadoes are rated
The National Weather Service rates tornadoes on what’s called the Enhanced Fujita Scale, which categorizes tornadoes from 0 to 5. According to the NWS website, the rating began use in 2007 and is based on estimated wind speed and damage.
NWS surveyors investigate the site of tornado damage to help inform estimated wind speed base on the level of damage found.
The meteorologist Quigley said any tornado at an EF-2 rating or above is considered significant.
The EF rating is determined by the following estimated wind speeds:
- EF-0: 65 to 85 mph
- EF-1: 86 to 110 mph
- EF-2: 111 to 135 mph
- EF-3: 136 to 165 mph
- EF-4: 166 to 200 mph
- EF-5: Over 200 mph
Wisconsin’s tornadoes by rating over the decades
According to data kept by NWS from 1950 through last year, Wisconsin tornadoes break down by EF rating as follows:
EF-0: 498 tornadoes
EF-1: 558 tornadoes
EF-2: 266 tornadoes
EF-3: 53 tornadoes
EF-4: 18 tornadoes
EF-5: 3 tornadoes
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