supercell storms -- fast and furious

supercell storms -- fast and furious

Summer storms can be sudden and scary–on Sunday, the sky turned dark at 3 in the afternoon. Lollapalooza  was evacuated, due to the weather. Performances were rescheduled due to the delay.

A tent collapsed in Wood Dale.  Sadly, one person was killed.

The most damage was in Rogers Park–rain, lightning, hurricane force winds, large hail,  trees knocked down, and power outages.   The  storm lasted about 15 minutes!

Later in the evening, another line of  supercell storms rushed through.  The National Weather Service has determined that an EF-1 tornado did touch down in the  Grayslake area.

The severity and duration of these storms is astonishing.  The blue sky the next morning is almost unbelievable.

It’s not that there was no warning. Weather forecasts even days before were saying conditions were ripe for  these kinds of storms arising. Officials at the festival  were kept informed of developing weather conditions,  and had contingency plans. Lollapalooza was closed early due to the storm at 10 pm.  There was quite a light show!  This Tribune graphic shows just how many lightning strikes there were on Sunday—

The development of such severe storms  and their intensity is  fast and furious. Here is Tom Skilling’s weather report.

Here’s a look at the structure of a supercell–




Just look at the height of those clouds. They can produce heavy rain, hail and strong winds.  See that tiny tornado way down there at ground level?  Even an EF-1 tornado can produce winds of over 100 miles an hour.

Supercells are big, fast, rotating, self-organizing systems.  That means they can change rapidly, and they can be difficult to predict. They look like a mother ship out of a science-fiction movie, and they are even more dramatic in reality!



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  • I think you have the two storms confused.

    The first storm was at about 3 p.m. and arose out of nothing some where around DeKalb county, and raced through Du Page and the middle of Cook County, and was the one that caused the tent to collapse in Wood Dale killing the father (the storm was reported to have struck at about 2:35) and the mess in Rogers Park. However, it did not get north of Evanston before going out over the Lake.

    There was a squall line and cold front that came down from Wisconsin in the evening, and the tornado hit about 8 p.m.

    The two unanswered questions I have are (a) how did a storm develop out of nothing in the afternoon, and (b) how could the tornado follow a consistent path 1/4 mile north of Illinois 120, when that road has a hook in it around Grayslake?

  • In reply to jack:

    Thank you, Jack. Yes, the tent collapsed in Wood Dale, and the afternoon storm hit Rogers Park. The tornado hit Grayslake in the evening. I will correct the confusion.

    The severe storm Sunday night caused Lollapalooza to be closed early, yet even as the lightning flashed, I could see planes taking off from O"Hare.

    Storm conditions were possible in the afternoon, and officials at the festival were prepared for that contingency. The suddenness and severity was shocking, though--that's the problem with those kinds of storms. They can arise out of a blue sky, and even NWS will say "as if they have a mind of their own." Maybe they really are Mother Ships. It would be a perfect cover.

    Tuesday evening--the Lake County News-Sun reports that according to NWS, the Grayslake tornado was so low to the ground it was not picked up on the radar!

  • Thanks for bringing this the analysis it needs. Well done.

  • In reply to Margaret H. Laing:

    Thanks so much for reading. I do like the Mother Ship theory...

  • Supercells are super scary! Even your picture made me a bit nervous.

  • In reply to Kathy Mathews:

    They sure are! Really apocalyptic...or the Mother Ship...

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