Worst of the worst of Wisconsin’s severe weather

In Wisconsin we know extremes. Our record book shows temps as high as 114° (Wisconsin Dells July 13, 1936) and as low as -55° (Couderay Feb. 2 & 4, 1996). But what about severe weather?

Does our biggest hail, fastest winds, and strongest tornadoes stand toe to toe with the worst severe weather in the heart of Tornado Alley? The answer is a resounding YES, though we don’t see these extremes as often.

Hail

The largest hailstone in Wisconsin’s history is 5.7” in diameter. It dropped on Wausau in 1921. While I don’t have a picture of this monster chunk of ice I can show you the runner up, a 5.5” rock of ice from Port Edwards in 2007.

Photo by Bart McCarthy

The largest hail ever recorded was 8”. It plummeted to the ground in Vivian, South Dakota on July 23, 2010.

Wind

In recent years southeast Wisconsin has experienced straight line (non tornadic) winds exceeding 100 mph! On the night of May 30, 1998 and into the morning hour of the 31st, a derecho screamed across southeast Wisconsin. The line of storms brought widespread damaging wind gusts exceeding 58mph which is the threshold for a severe thunderstorm. But in a few spots “downbursts” boosted the wind speeds to over 100mph.

One gust northeast of Watertown (southern Dodge Co.) was measured at 128mph. This wind speed correlates to a category 3 hurricane, or about the strength of Hurricane Katrina when it made landfall in southern Louisiana.

Peak wind gusts in mph

On July 4, 1977, Mother Nature brought her own fireworks to the Northwoods of Wisconsin. A derecho, similar to the southern Wisconsin event 21 years later, delivered peak wind gusts estimated at 135mph to the Flambeau River State Forest.

Tornadoes

Since 1950 Wisconsin has been hit with three F-5 tornadoes (we have yet to see an EF-5 tornado since the scale was switched circa 2007). The first of these struck Menomonie in northwest Wisconsin on June 4, 1958.

Barneveld took a direct hit from an F-5 on June 7, 1984. This twister struck in the middle of the night catching many off guard.

Finally, the well known (for these parts) Oakfield tornado on July 18, 1996. It cut a path through Oakfield as an F-4 before leaving town and strengthening to an F-5. Years later I spoke with one of the survivors who described looking up through the clothes chute of his basement only to see the rest of his house get blown away.

Since very few structures survive wind speeds above 200mph it is difficult to compare F-5 tornadoes. Essentially, the weakest F-5s are just as bad as the strongest.

But since we’re comparing numbers, the Oakfield tornado is estimated to have a peak wind gust around 260mph. The strongest wind ever measured was by a mobile doppler radar on wheels when the May 3, 1999 Moore, OK tornado spun at up to 301mph!