Twin Mesoscale Convective Vortexes Over Lake Superior!

I've talked before about Mesoscale Convective Vortexes -- and we had a pair of them over Lake Superior Wednesday. I pulled up 3-D radar data just before the storms made "landfall":

Mesoscale low pressure systems like this are not common, but are also not unprecedented. Although usually associated with thunderstorms, the lake-effect snow Sunday was convective enough to spawn them. Here's a look at close-up shots from the MODIS satellite archive:

My friend, Scott, over at the CIMSS satellite blog has satellite loops, wind maps and more in-depth information. Below my radar animation, he says:

"As the feature approached the Upper Peninsula of Michigan, a secondary mesovortex could be seen to the east-southeast of the larger primary mesovortex. These mesovortices produced bands of heavy snowfall and strong winds (with gusts as high as 60 mph offshore at Stannard Rock, and 46 mph inland at Marquette), which reduced surface visibility to less than 0.1 miles at times."