Friday, May 26, 2017

Deadly Chetek Tornado Was Wisconsin's Longest on Record

Jon Erdman
Published: May 25, 2017


A deadly tornado which tore through northwest Wisconsin on May 16 left the longest damage path in the Badger State since modern records began, according to the National Weather Service.
(MORE: Tornado Central)
A storm damage survey completed Tuesday by the National Weather Service office in Chanhassen, Minnesota, found the tornado that killed one in a mobile home park near the town of Chetek was actually on the ground for 83 miles over almost an hour and a half from southeast Polk County to southwest Price County.
(INTERACTIVE: Experience the Formation of a Tornado)
The track of mid-level rotation as seen by radar corresponding, in part, to the Wisconsin record long-track tornado of May 16, 2017.
(NWS-Chanhassen, Minnesota)

The previous longest Wisconsin tornado path was also in northwest Wisconsin, an 80-mile long path through Burnett, Pierce, Polk, and St. Croix Counties on May 10, 1953, according to Tim Halbach, warning coordination meteorologist at the National Weather Service office near Milwaukee.
Modern historical tornado path records - dating to 1950 - are not as straight-forward as, say, temperature or precipitation records.
(MORE: The Future of Tornado Warnings)
"Some early long-track tornadoes, especially before the 1960s, are suspect due to the lack of data for post-storm analysis," Jeff Last, warning coordination meteorologist with the National Weather Service in Green Bay, told in an email.
In this case, Halbach said in an NWSchat entry Wednesday that a pair of seemingly longer-track tornadoes from May 10, 1953 were likely not a single, continuous tornado path, but rather a number of separate tornadoes from one parent thunderstorm, known as a "tornado family."
Last said aerial surveys, drones, high-resolution satellite imagery and dual-pol Doppler radar all help present-day meteorologists determine if a supercell produced multiple tornadoes or simply one long-track tornado.
In fact, a drone was used to assist in the Chetek tornado survey, according to NWS-Chanhassen.
(MORE: Most Tornado-Prone Counties in the U.S.)
The most recent tornado with a comparably long path so far north happened almost 30 years ago, a July 11, 1987 F3 tornado in Michigan's Upper Peninsula, which was at least 71 miles long.
With historical tornado paths of higher confidence, path lengths that long, while thankfully uncommon, typically occur in the Deep South, central and southern Plains, Ohio Valley or Lower Midwest.
Some Notable Tornado Path Lengths
(Sources: Dr. Greg Forbes/The Weather Channel, Midwest Regional Climate Center)
DatePath Length (miles)Location
Mar. 18, 1925151 to 235 Tri-State Tornado (MO/IL/IN based on 2012 research)
Apr. 24, 2010149LA/MS (Yazoo City)
Apr. 27, 2011132Hackleburg, Phil Campbell, AL
Apr. 3, 1974109Monticello, IN (after gap, previous tornado path removed)
Nov. 27, 198883From Raleigh metro to northern NC
While the lion's share of damage with this tornado was tree and minor building damage, the NWS survey found one home in Rusk County "collapsed down to the foundation," prompting an EF3 rating with winds up to an estimated 140 mph.
(MORE: Why Rating Tornadoes in Rural Areas is Challenging)
Damage near Chetek was found to be "high-end EF2", according to NWS-Chanhassen.
Wisconsin averages just under two dozen tornadoes a year. The average path length of a Wisconsin tornado is only about 3 to 6 miles, according to data compiled by the National Weather Service in Green Bay.
The longest path of the only three F5 tornadoes in the Badger State since 1950, the June 1984 Barneveld tornado, was less than half as long – 36 miles – as the Chetek tornado.
(MORE: Your Odds of Being Hit by a Tornado)
Jonathan Erdman is a senior meteorologist at and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7. Follow him on Facebook and Twitter.
MORE: Tornadoes in History

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