April 25, 2008 - Wyocena Tornado - Columbia County

Wyocena Tornado - Columbia County

April 25, 2008

On Friday, April 25, 2008, several clusters of severe storms moved northeast through south-central and southeast Wisconsin. Based on an intial NWS damage survey, subsequent video tapes and digital pictures from three severe weather spotters, and other spotter reports, we have concluded that two tornadoes spun up in Columbia County during the late afternoon hours:

1. One brief EF0 tornado spun up about 3.3 miles west-southwest of Wyocena at 520 pm and resulted in just tree damage. This tornado was rain-wrapped and difficult to see.

2. A longer-tracked tornado spun up about 2.0 miles east of Dekorra at 518 pm and traveled northeast for about 27 miles to a point about 1.8 miles southeast of Markesan. This tornado intensified to an EF1 status with winds of about 100 mph, and was rain-wrapped at times. Preliminary Columbia County Emegency Management damage estimates indicated that 4 homes had minor damage and one home had major damage. Additionally, 2 agricultural buildings had minor damage, 2 had major damage, and 3 were destroyed. At least 2 vehicles were damaged, 2 horses were injured, and many trees sustained damage. After this tornado moved east of Wyocena it diminished in strength to an EF0 rating and only damaged trees on its track into southeast Green Lake County. Information about the EF-scale can be found here: Enhanced Fujita Scale

In the early and late stages of this tornadoe’s life it wasn’t in constant contact with the ground. As the parent supercell thunderstorm moved northeast through western Fond du Lac County it maintained its internal circulation and generated at least one funnel cloud report in northwestern Fond du Lac County.

The first map below is the path that the tornado took.

April 25th tornadoes

The following are radar images from the storm. Note the "hook" shape of the radar echo as the parent supercell thunderstorm moves into northeastern Columbia County. In the Storm Relative Velocity images on the right side of each pair note the so-called "velocity-couplet" which represents the circulation or rotation inside the updraft tower of the supercell thunderstorm. This internal rotation is referred to as "mesocyclone" by meteorologists and severe weather spotters.

Below are some images from the NWS Survey by former Warning Coordination Meteorologist Rusty Kapela and Science and Operations Officer Jeff Craven

These images are all from the area around Wyocena.