Double Derecho: July 19-20th Storm Recap

July 25, 2019 1 Comment

 The “double derecho” event brought extensive wind damage across most of northern and central Wisconsin during the evening of Friday July 19th and the morning of Saturday July 20th. Here’s a complete recap of what happened both days (this post will be updated if new storm reports are issued):

Friday June 19th

A rare PDS (Particularly Dangerous Situation) Severe Thunderstorm Watch was issued around 6 p.m. Friday evening for most of the viewing area. The Storm Prediction Center was calling for a few isolated tornadoes and widespread significant straight-line wind gusts up to 105 mph.

A significant line of storms was already producing tennis ball sized hail in east central Minnesota during the afternoon and continued to produce significant wind damage as it moved into west central Wisconsin. This damaging area of storms produced two tornadoes near village of Turtle Lake. The brunt of the bowing line of storms then moved into Taylor and Clark counties, while a separate supercell tracked across southern Price county into southern Oneida and northern Lincoln counties.

The bowing line of storms ended up producing two tornadoes west (EF0 – peaks winds 85 mph) and north (EF1 – peak winds 110mph) of Withee. The EF0 west of Withee caused significant damage to the roof of a barn and a silo at a farm on county road O. Numerous 10-20 inch diameter trees were uprooted and power lines were brought down from Neillsville to Abbotsford. The northern edge of this line of storms also produced a 61 mph gust in Dorchester.

Withee Damage Credit: NWS La Crosse

Meanwhile the supercell produced egg sized hail in Price county south of Phillips, and then produced two separate tornadoes. The first one touched down near Tripoli on the Lincoln/Oneida county border and was rated an EF0 with peaks winds of 75 mph. A second, stronger tornado touched down west of Pelican Lake and was rated an EF1 with peak winds of 100 mph. Large trees were also blown down in Rhinelander.

Tripoli Tornado. Credit: Jason Jerome and Jennifer Hess

Eventually the line of storms caught up with that supercell and merged together over Elcho and continued through Langlade county.

Credit: NWS Green Bay

This is where the most significant wind damage occurred. The National Weather Service in Green Bay determined that a macroburst, a large downburst of straight-line winds up to 100 mph, produced a damage path 15 miles wide and 25 miles long across the northern/eastern half of Langlade and western Oconto counties. Tens of thousands of trees and power lines were snapped or uprooted across the counties.

Farther south, the line of storms continued into central Wisconsin, after  where it produced an EF1 tornado in Knowlton and straight-line wind damage throughout Marathon county. This tornado was on the ground for 9 miles, produced 90 mph winds, and destroyed a barn and several roofs of nearby buildings. Not only did the straight-line winds cause tree and power line damage throughout the county, there was a well constructed 100 ft by 60 ft pole barn in Edgar that was completely destroyed by estimated 65 mph wind gusts.

Barn destroyed Knowton. Credit: NWS Green Bay

This line of storms continue to produce widespread tree and power line damage across Wood, Portage, and Shawano counties, with Shawano county taking the brunt of the wind damage. These storms continued to weaken as they pushed into Juneau, Adams, and Waushara counties, but they were still strong enough to produce some tree and power line damage in Big Flats. These storms also produced hundreds of thousands of lightning strikes, and because it moved through just before sunset, many people were able to capture an awesome rainbow along with the lightning!

Photo credit: Keith Simson Town of Marathon

 

Saturday July 20th

The weather turned quiet during the overnight hours Friday night in our area, but a second derecho was already developing and moving across portions of South Dakota, southern Minnesota, and northern Iowa. Around 9 a.m., this line of storms began producing wind damage across Trempealeau and Jackson counties. It even produced two EF0 tornadoes (peak winds 80-85 mph) near the Town of North Bend. This line of storms picked up in speed and intensity as it moved through Jackson and Clark counties, with numerous reports of widespread wind damage coming in between 9:45 -10 a.m from Black River Falls, to Hatsfield, to Neillsville. This line of storms even blew a semi off of HWY 10 near Neillsville.

The line of storms began moving over 65 mph as it pushed through Wood and Marathon counties, causing extremely severe wind damage. The “weaker” portion of the line caused a 64 mph wind gust at the Marshfield airport, and two separate 74 mph gusts at the Wausau airport. Another 64 mph gust occurred at the Wausau airport, with both gusts taking News 9 off the air during extended severe weather coverage.

Large trees on Wisconsin Rapids home. Photo credit: Lisa Vechinski Williams

The wind was so strong when it moved through Wisconsin Rapids that it broke the ASOS station used to measure current weather conditions. Power outages impacted nearly all of Wood county, with many trees falling on homes in Wisconsin Rapids.

The line of storms got even stronger as it crossed into Portage county and southeastern Marathon counties. There was incredible damage in Lake DuBay, including at the Rivers Edge Campground where numerous campers were destroyed.

Rivers Edge Campground Photo Credit: Becky Bohte Chapman

 

Incredibly extensive wind damage occurred all across Portage county. Plover was one of the hardest hit areas, and a place where power still hasn’t been restored 5 days later. There, a 86 mph wind gust was recorded at Tim Bubla’s weather station. The wind was powerful enough to blow in both of the glass front doors of the Menards in town. The storm then produced an estimated 90 mph wind gust in the Town of Arnott. By this time, a little hook was forming at the leading edge of the most devastating winds, so the National Weather Service issued a Tornado Warning for the eastern portion of Portage county, including Amherst, and for central Waupaca county. Extensive damage occurred in Amhert, so much so that the Portage county fair was cancelled for the remainder of the weekend. Widespread wind damage continue across all of Waupaca county and into Outagamie county. 5 additional tornadoes were confirmed in this area, including an EF0 near the Waupaca airport with estimated peak winds of 85 mph and an an EF1 with 90 mph winds near New London.

Damage in Stevens Point/Whiting area. Photo credit: Kim O’Flaherty

In total, the two derechos produced 14 confirmed tornadoes in Wisconsin on Friday and Saturday. At this time of this post (2 p.m. on Thursday July 25th), 40% of Elcho remains without power and over 1,000 residents in the Plover area still don’t have power.

Path of both derechos. Yellow = Friday night, Orange = Saturday morning

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  1. Mike Plant says:

    I have been trying to find information on these two derecho events on NWS or NOAA websites and am not able to find anything. Wondering if you could provide links to the information from NWS and/or NOAA.

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