May 30, 2003

Statistics:

Initial Target: South of Rockford, IL
Departure: Bolingbrook, IL 4:00 pm CDT
Arrival: Bolingbrook, IL 8:45 pm CDT
Intercepts: Roscoe, IL 6:30 pm CDT
Tornadoes: 0
Hail: Non-Severe Pea Sized
Wind: Non-Severe (30 -  40 mph est.)
Features: Shelf and remnants of meso and lowering
Miles: 211

Summary:
Waited until red box went up in North Central IL before leaving, targeting south of Rockford.  Tornado reported on the ground in North Winnebago county as we entered the south part of the county.  Intercepted this cell at Roscoe at 6:30.  Photographed the shelf cloud and remnants of a meso and lowering.  Passed through the precip core of this storm on the way back and encountered some pea sized hail.

Crew and Equipment:
One vehicle chase team included:  Mike Collart and Adam Nekola.  Equipment consisted of a NOAA weather radio and cell phone.  Photography by Adam Nekola.

Details:

My second chase and a much better one at that.  Learning our lesson from last time, this was a daytime chase.  Watching the changing weather forecasts and target areas in the morning and afternoon, we didn't leave until a tornado watch was finally issued for North Central IL and into Wisconsin.  Leaving Bolingbrook at 4:00 pm we had about four more good hours of light left.

 

When we left the radar scopes were clear except for departing showers in Indiana.  There was a cloud deck still as scene here.  We cleared it about a half hour later where the sunshine's warmth was creating the unstable conditions we were after.

 
Taking I-88 to Dekalb we headed north on I-39 towards Rockford.  Just before entering Winnebago county we saw a modest looking cell to our west.  It was intensifying as we passed it and I later learned from the weather radio and other chase accounts that this cell dropped a brief tornado.  No warnings had been issued for it at the time so we continued north towards another cell that did have a recently issued tornado warning.  Law enforcement near the IL/WI border in northwest Winnebago county had reported a touch down.

Doppler at 6:34 pm CDT

Exiting I-39 between Roscoe and Rockton we got our first look at the storm, see right.

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We stopped by a school in Roscoe to observe.  A shelf cloud was rapidly approaching and behind it some suspicious lowerings.  Sirens wailing, strong south easterly winds abruptly changed to north westerly and intensified as the gust front went overheard.

 

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This is the feature that grabbed our attention.  A grungy lowering beneath a horseshoe shaped base.  Spotters reported a funnel near Roscoe at approximately the time this photo was taken.  Was this the feature?  Is it scud, or the remains of a wall cloud or funnel?  Due to my lack of experience in the field, I don't know. 

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Here is a close up of the feature as it approaches.  Although Doppler was reporting strong rotation, it was hard to detect at the base. 

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20 second QuickTime animation

Low clouds were building up along the feature.  If only we had the view of the two atop the school.

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Panning left you can see the shelf cloud's profile making a funnel like point and the meso base behind it.  As this part of the storm passed overheard you could see it kicking up quite a bit of dust.

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Mike and I watch the features to the west.  Notice how dark the precip core is to the north.

 
We got a up close and personal with the precip core as we headed back.  Torrential horizontal rains mixed with pea sized hail.  A real treat to drive in.  Not driving too much under the speed limit, a pickup tried to pass but had to swerve back when an oncoming car emerged from the wall of water.  I pulled over and let the crazed motorist pass.  The east highway took us right into the center of the southeast moving storm.  We got ahead of it and took I-90 home.
The perfect way to end an exciting and educational chase experience: a beautiful sunset.

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Almost over but not quite yet:

Of course we drive over two hundred miles only to learn on the way back that a tornado warning is currently in effect for my backyard in Bolingbrook.  We saw the back end of the storm from 355.  Quite a bit of CG and CC.  Fox in Chicago showed video of "funnel" which looked a lot like a shelf, but there were numerous reports of a rotating wall cloud in Plainfield (this town has seen enough).  Reviewing the radar and storm reports, I'm not disappointed in our choices.  We got the better storm.
Lesson learned:
  • Drive slow on wet roads.  Hydroplaning is not fun.
  • I know well that when they issue a warning its too late to jump in the car and try and catch anything.  The same can be said about a watch if you aren't in it.  We arrived in Roscoe with not more then a few minutes to spare before the storm struck.  Arriving an hour earlier would have made things less hectic and perhaps we would have bagged the nader that dropped before we got there.

Look at those sexy storm chasers!

From left: AJ, Mike, Ski