My brother Wil and I chased a tornadic supercell across Will County, near Interstate 55 from Dwight, IL into the southern suburbs of Chicago (Monee, Richton Park). The tornado produced weak damage in the town of Manhattan, IL.
This was a peculiar chase. I'd been eyeing the day for a potential local chase day, but the morning of things got muddied up. A morning MCS pushing out of Missouri left question marks as to how significant recovery and destabilization would be across the ideal target area for potential supercells and tornadoes in north-central Illinois.
Short-range guidance became particularly useless as it struggled to resolve the morning storms. Models continued to intialize showing a large area of storms across the target area during the lunch-hour that simply did not exist. Because of this, I focused only on satellite and surface observations. Around 1 PM, things began to strike a pattern recognition chord in me for the potential of mini-supercells and brief tornadoes along a boundary in north-central/northeast Illinois. It looked good enough that with a free afternoon and evening already set aside for this purpose, ignoring short-range weather models and reliance on my gut feeling said to just get in the car and go.
We targeted an area north of Bloomington, IL on I-39 for a starting place, being able to hedge north or east depending on which area looked best an hour or two later. We stopped briefly in El Paso at the junction of I-39 and Hwy 24 before a few "specks" began to appear on radar to our east down 24 in the Dwight area. After a few attempts at storms in this area, I decided to make moves. This convection would eventually move into an area at least marginally favorable for brief tornadoes. I was cautious about getting excited about seeing a tornado, but felt pretty decent at our chances of some supercellular structure.
Early attempts had a very clear "mini-supercell" look which gave me the hope I needed early on to stick with these "showers" as they percolated along the boundary. They'd erupt, take on a quick supercell look, but then fall likely due to weak mid-level lapse rates. But, with early looks like this I knew to just stick it out until one storm could root and take off.
It was an attempt just southwest of Manhattan, IL that finally went nuts.
Clearly taking a quick turn toward a supercell that's capable of producing a tornado.
Tornado touches down in/near Manhattan, IL:
A smaller rope can be seen in front of the larger tornadic circulation:
Wide shot of supercell and funnel cloud/tornado over Manhattan:
Second circulation quickly developed and nearly touched down near Andres, IL. Circulation at cloud level was rather strong, but no ground circulation was observed:
Supercell, still capable of producing tornadoes now enters heavily populated areas of the southern Chicago suburbs:
Gorgeous RFD cut on the back side of the supercell as I begin to fall back due to a combination of more populated area and loss of daylight. It no longer makes sense to attempt to stay on this storm, so we fall back and call off the chase.