On September 24th, 2011 an unseasonably cold air mass flowed over the warm waters of Lake Michigan creating very unstable conditions in the low levels of the atmosphere.  The lake surface temperature was estimated to be in the lower to middle 60s F.  Meanwhile, the ambient air around 4000 feet was estimated to be 40 degrees F creating very unstable conditions over the low levels of Lake Michigan.  Updrafts from nearby showers and thunderstorms resulted in convergent boundaries over the near shore waters of Lake Michigan.  The combination of the unstable atmosphere and these boundaries caused five observed waterspouts just offshore of downtown Milwaukee, and two observed waterspouts just offshore of Kenosha.  The waterspouts remained offshore and did not cause any property damage.  Most of the waterspouts were filmed by WISN-TV.

Waterspout in NORTH PT LT TO WIND PT WI, LAKE MICHIGAN
From 24-SEP-11 09:40:00 to 24-SEP-11 09:45:00 (CST-6)
Location: NORTH POINT LTHOUSE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This was the last and furthest north in a series of five waterspouts observed in Milwaukee Bay that morning.  This waterspout was observed by multiple people at the Milwaukee Yacht Club.

Waterspout in NORTH PT LT TO WIND PT WI, LAKE MICHIGAN
From 24-SEP-11 09:30:00 to 24-SEP-11 09:40:00 (CST-6)
Location: CUDAHY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Coast Guard

This was the fourth in a series of five waterspouts observed in Milwaukee Bay that morning.  This waterspout was observed by multiple people at the Milwaukee Yacht Club as well as Coast Guard personnel on ship.

Waterspout in WIND PT LT WI TO WINTHROP HBR IL, LAKE MICHIGAN
From 24-SEP-11 14:12:00 to 24-SEP-11 14:17:00 (CST-6)
Location: KENOSHA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

One of two waterspouts that developed just east of the Kenosha lake shore, caused by very unstable conditions in the low levels of the atmosphere over Lake Michigan and weak low level convergent boundaries caused by nearby showers.

Waterspout in WIND PT LT WI TO WINTHROP HBR IL, LAKE MICHIGAN
From 24-SEP-11 14:22:00 to 24-SEP-11 14:36:00 (CST-6)
Location: KENOSHA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

One of two waterspouts that developed just east of the Kenosha lake shore, caused by very unstable conditions in the low levels of the atmosphere over Lake Michigan and weak low level convergent boundaries caused by nearby showers.

Waterspout in NORTH PT LT TO WIND PT WI, LAKE MICHIGAN
From 24-SEP-11 08:45:00 to 24-SEP-11 08:55:00 (CST-6)
Location: CUDAHY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This was the first of five waterspouts that developed just southeast of Milwaukee Harbor.

Waterspout in NORTH PT LT TO WIND PT WI, LAKE MICHIGAN
From 24-SEP-11 09:00:00 to 24-SEP-11 09:20:00 (CST-6)
Location: CUDAHY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This was the second of five waterspouts observed just southeast of Milwaukee Harbor.

Waterspout in NORTH PT LT TO WIND PT WI, LAKE MICHIGAN
From 24-SEP-11 09:02:00 to 24-SEP-11 09:23:00 (CST-6)
Location: CUDAHY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Coast Guard

This was the third in a series of five waterspouts observed in Milwaukee Bay.  Observed by commodore of Milwaukee Yacht Club.