Late-season tornado hits east side of Madison, Wisconsin

Late-season tornado hits east side of Madison, Wisconsin

A late-season tornado swept through the east side of Madison, Wisconsin on Saturday, October 7, 2017, damaging dozens of businesses and cutting off power to at least 600 people. After surveying the damage, the National Weather Service's Milwaukee region office said the tornado swept through East Washington Avenue and rated it EF-0

Tornadoes in Wisconsin in October aren't common, but not unprecedented, NWS said. Late Saturday afternoon (local time), a line of showers developed along a frontal boundary pushing northeast through southern Wisconsin.

These showers weren't big/tall enough to produce lightning, but there was enough shear (changing wind directions and wind speeds) and instability, coupled with a very moist atmosphere, to cause many of the showers to rotate. The shower that moved through the east side of Madison was strong enough to produce a tornado along East Washington Ave, tracking northeast to the Interstate 39/90.

Peak winds were estimated between 112 and 129 km/h (70 and 80 mph). The tornado had a path length of 6.7 km (4.2 miles) and width of 46 - 91 m (50 - 100 yards). It touched down at 04:59 CDT and was on the ground for 7 minutes. There are no reports of casualties or injuries.

Madison tornado path - October 7, 2017

Madison, WI tornado path - October 7, 2017. Credit: NWS

Credit: NOAA/GOES-16, UW-CIMSS

The visible animation, above, from GOES-16, shows a thin line of weak convection moving through the central part of the state.

Below are a series of radar images (4 panel) that begin at around 16:58 CDT and end around 17:12 CDT in the Sun Prairie area. 

The top left quadrant is reflectivity, top right is velocity, bottom left is reflectivity and bottom right is Correlation Coefficient (CC). CC is is a dual-pol product that allows us to see if debris is being lofted into the storm from a tornado. You'll see at around 17:02 there is a good CC signature of the debris (mostly leaves).  

Madison tornado genesis - 16:58 CDT, October 7, 2017

Madison tornado genesis - 16:58 CDT, October 7, 2017

Madison tornado genesis - 17:02 CDT, October 7, 2017

Madison tornado genesis - 17:02 CDT, October 7, 2017

Madison tornado genesis - 17:06 CDT, October 7, 2017

Madison tornado genesis - 17:06 CDT, October 7, 2017

Madison tornado genesis -  7:11 CDT, October 7, 2017

Madison tornado genesis -  7:11 CDT, October 7, 2017

"All of this information is preliminary and subject to change as our survey crew assesses the damage, path, strength, and timing," NWS said. "We have received reports of several trees down, some trees on homes, and damage to a few businesses."

The pictures below are from John Marion and provided by Milwaukee SKYWARN:

Madison tornado, October 7, 2017 - Damage

Madison, Wisconsin tornado damage - October 7, 2017. Credit: John Marion, Milwaukee SKYWARN

Madison tornado, October 7, 2017 - Damage

Madison, Wisconsin tornado damage - October 7, 2017. Credit: John Marion, Milwaukee SKYWARN

Madison tornado, October 7, 2017 - Damage

Madison, Wisconsin tornado damage - October 7, 2017. Credit: John Marion, Milwaukee SKYWARN

Featured image credit: Live Storms Media

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