Tonight marks the tenth anniversary of one of the most memorable severe weather events of my career. Here's a description from our National Weather Service:
You can click on the above image to download the radar animation from the Storm Prediction Center’s "About Derechos" web page.
This Friday/Saturday marks the 10 year anniversary of one of the most widespread severe wind events in recorded Wisconsin history. Southern Wisconsin residents and travelers experienced a significant and devastating thunderstorm wind damage event during the late evening hours on Saturday May 30th into the early morning hours of Sunday May 31, 1998. Southern Wisconsin was impacted generally between 1 AM and 4 AM local time.
The damage across the Milwaukee/Sullivan county warning area (CWA) totaled about $55 million to property and about $1.49 million to crops. Many trees and power lines were blown down and hundreds of structures across Southern Wisconsin were damaged.
Three fatalities occurred during, or immediately after, the event. One was direct, and two were indirect. At least 37 injuries were reported. At one point just after the event 60,000 customers were without electricity in South-Central Wisconsin, and about 170,000 customers were without electricity in Southeast Wisconsin.
This severe wind event was termed a derecho, which is basically a widespread and long lasting wind storm that is associated with a line of thunderstorms. This line of thunderstorms gained strength over Minnesota and Northern Iowa and then swept east across Southern Wisconsin at 50 to 60 mph.
Of the 20 counties in the Milwaukee/Sullivan CWA, 12 experienced gusts of 100 mph or greater, either based on measurements or estimated based on damage surveys. Below is a summary of some of the notable wind gusts from this event.
128 mph measured 1.5 miles northwest of Lebanon in Dodge County.
105 mph measured in Erin in Washington County.
103 mph measured in Greenfield in Milwaukee County.
100 mph measured at WITI TV station in Milwaukee County.
100 mph measured in Marshall in Dane County.
90 mph measured in Port Washington in Ozaukee County.
83 mph measured in Ripon in Fond du Lac County.
80 mph measured at the Waukesha Airport in Waukesha County (KUES).
71 mph measured at WTMJ TV station in Milwaukee County.
68 mph measured in Briggsville in Marquette County.
64 mph measured at the Watertown Airport in Jefferson County (KRYV).
61 mph measured at Mitchell International Airport in Milwaukee County (KMKE).
61 mph measured at the National Weather Service in Sullivan (KMKX).
Some notable damage also occurred around the area. Estimated peak wind gusts from Sauk, Columbia, and Iowa Counties were in the 100 to 120 mph range based on significant tree damage and some damage to structures. In Lafayette County, 10 city blocks in Darlington were closed due to debris. In Dane County, there was a swath of particularly strong winds from Waunakee to Sun Prairie to Marshall. Cars were blown off Interstate-94 north of Madison. A roof was torn off a home in Marshall.
In Dodge County, there was an accident on Highway 41 when the strong winds blew over a semi-tractor truck. Near Clyman, hay wagons were blown onto the second floor of damaged barns. At New Glarus Woods State Park in Green County, tents were shredded and many trees blown down. At the West Bend Airport in Washington County, 6 hangars and 6 planes were destroyed. At Mitchell International Airport in Milwaukee County, some of the hangars were blown in. Some stripped roof shingles were found to be embedded in nearby siding in Cudahy.
The peak wind gusts in the 110 to 130 mph range that were found in small pockets across Southern Wisconsin during this event are equivalent to the maximum 3-second wind gusts found in an EF-2 tornado (
click for EF-Scale). Such powerful winds illustrate the importance of seeking shelter when severe thunderstorms approach!
The derecho pushed east during the early morning hours across Lower Michigan, and eventually into Southern Ontario and New York during the morning hours of May 31st.
