A Near Catastrophe for Chicago: September 22nd 2006
The event September22nd 2006 will be remembered mostly for the F3 and F4 tornadoes that occurred across Missouri and parts of Illinois. On a more local scale though, It was also a day where the city of Chicago came close to a major disaster that many probably don't even know about.
To get this out of the way though, I DID chase this day, but I was downstate. Cool, huh? Not. In 2006 I was still new to chasing away from home. I chased with no laptop and no radar. All I had was a NOAA radio. The only radar Images I saw were at rest stops along the interstate. I busted this chase big time. It stung being 3hrs from home only to receive a call from my father about the sirens going off and there being some "really dark and crazy moving clouds."
Without getting to technical [and with no visual representation to back it up.] The day featured an unseasonably strong storm system. The Storm Predication Center had put out a Moderate risk for severe storms and significant tornado probabilities, mostly for areas down state.
Naturally most chasers set their target areas within the area of highest probability and I was no exception. If I was a better forecaster back then I may have been able to spot the threat that was brewing in the area on the edge of the lower probabilities.
As the low pressure system of the massive storm system began to deepen [get stronger.] A warm front began surging northward to the point where it was farther north than the center of the storm itself. This brought very warm and moist conditions to the Chicago area. More importantly though, with such a dynamic system in place, the lifting warm front backed the winds out of the southeast as they began to rotate around the massive storms center. This enhanced something called helicity [the airs ability to rotate.] This accompanied by the strong heating, and warm air began to brew a rare breed of thunderstorm. The supercell.
The following series of archived radar images will help tell the story. Supercell storms are the most powerful on the planet and the ones responsible for the most violent tornadoes. Its these elusive monsters that are the main target of storm chasers. Storms like these are much more common in the plains states, not so common around here and other parts of the country, but they can and DO occur.
The first radar Image shows the first supercell, with a well formed hook echo just south of Geneva. The hook echo region circled is where a tornado would likely occur with such a storm. The rapidly rotating air causes precipitation to be drawn around, but sometimes not completely around, thus the hook formation.
The Image also shows the second storm, although slightly more elongated. This storm is also showing signs of a forming mesocyclone which would be represented by a hook echo. All in all 3 tornadic storms would form and track over the same area. Each and every one of them capable of producing a tornado at any moment.
The next image shows the 3 supercells. The first one with a very well defined hook echo. This hook echo and associated rotation passed directly over O'hare Airport. The local observers reported a rapidly rotating wall cloud. Luckily that is all there was as this situation could have been the worst one imaginable, it was rush hour and things were extremely busy.
The image also shows a new storm trying to form in the SW suburbs as well.
The next image shows the storms starting to congeal into a line. This is pretty common in most storm setups. The supercells at this point often become embedded within the line. This can be even more dangerous because it often gets messier and harder to see what is actually going on. Plus to the untrained eye it looks like just another line of storms coming through. The hook echo on the first storm is still very well defined!
Storm number 4 is having a hard time organizing. There are a number of factors that could cause this. It is either too far away from the better dynamics of the warm front. Storm 3 could also be ingesting it with its powerful inflow. If storm 4 were able to mature, the entire metro area would have been at risk from any one of these storms.
Finally it happened. A tornado touched down IN CHICAGO at the Loyola University campus. Luckily, this touchdown occurred just before the Lake Michigan shoreline and the tornado quickly moved onto the water. Only tree and light roof damage was reported. After going over images and data I believe it was storm #2 that became the one to produce.
Image of the tornado moving onto Lake Michigan.
You can also see the hook echo from storm #3 not far behind it. This storm prompted a tornado warning in downtown Chicago, the first in over a decade.
Radar Images alone cannot illustrate the whole story though. Since I was busting down state and couldn't document any of this myself. Since we live in the digital age and everyone owns a recording device of some sort, and Chicago being densely populated sure enough some of these events were captured on camera.
These are NOT my videos.
The first video actually shows the tornado touching down at Loyola! It is incredible, you can see the rapidly rotating funnel cloud, it then gets obscured behind a tree and when you have full visibility once again you can see the circulation over the lake.
The next video is a view of downtown Chicago during the tornado warning for storm #3. The video is looking mostly west and south at would could be the rear flank area. You can clearly see a wall of precip being wrapped around. If there was a tornado here it likely would have been behind the precip and very hard to see!
I have tried to compile some of these events into a Google map to show how close these storms were to each other and how they would have affected nearly the same areas. The densely populated nature of these areas is what makes this threat so significant.
This tornado was never recognized on SPCs list of storm reports for the day.
The local NWS also had an excellent write up on this event, one that would have put the one I am doing to complete shame. It has also disappeared from their list of archived news stories. I wont get into X-file type conspiracy theories though. The tornado is listed on the NCDC's [National Climactic Data Center] database though:
Event: Tornado
Begin Date: 22 Sep 2006, 05:02:00 PM CST
Begin Location: Chicago... Read More
Begin LAT/LON: 41°50'N / 87°39'W
End Date: 22 Sep 2006, 05:03:00 PM CST
End Location: Chicago
End LAT/LON: 41°50'N / 87°39'W
Length: 0 Mile
Width: 50 Yards
Magnitude: F0
Fatalities: 0
Injuries: 0
Property Damage: $ 0.0
Crop Damage: $ 0.0
Local legend around Chicago states we are immune to tornadoes for a number of reasons. One of those reasons is that our areas proximity to Lake Michigan protects us. Like all myths, it was spawned over time by twisted facts. Chicago's weather is greatly impacted by Lake Michigan, and YES it can, and sometimes does kill thunderstorms before they reach the city. This happens because the cool water can stabilize the atmosphere above the lake. Storms cannot survive in a stable environment.
However, this is not always the case. September 22nd 2006 illustrates this perfectly. Especially the fact the tornado didn't touch down UNTIL it reached the lake is proof alone that the lake does not protect us. The atmospheric conditions that have to come together to make such storms have far greater power than anything the city has to offer. Tornadoes have touched down in the past far from the city and tracked all the way to the lake.
For whatever reason the Chicago area has seen a lull in tornado activity in recent decades. The NWS has a fascinating article about this on their site. Link: http://www.crh.noaa.gov/lot/?n=SigChiTorn
The bottom line is the events of this day could have been catastrophic. The same storm system that spawned these storms spawned storms in other parts of Illinois as well as Missouri that devastated towns and killed several people. These storms produced tornadoes up to F4 strength. One little thing was missing from the storms up here that kept them from producing similar tornadoes of that strength. Next time the area might not be so lucky. It is very important to not be ignorant to the threat, it will happen. We cannot dodge the bullet forever.
Hopefully you've found this article somewhat interesting. Thank You for checking it out!
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