June 19 Central Illinois and Indiana Storm Chase

After Iowa’s blue-sky bust on June 18, yesterday provided some welcome and much-needed activity. Between illness and May’s ridge of steel, my chase expeditions this year have been limited. The Edina, Missouri, tornado of May 13 has been my only tornado to date for 2009. Yesterday did nothing to improve that statistic, but it did offer a vigorous, classic supercell with some great structure that ensured my 1,650-mile, two-day chase with my buddy Bill Oosterbaan wasn’t a complete washout.

For that matter, storms did finally fire in eastern Iowa, and while Bill and I were too late to catch the big mutha that slammed Prairie du Chien (Ben Holcomb, if you happen to read this, great job on tracking that beast into the hills and jungles of Wisconsin!), we did manage to latch onto the one that followed in its footsteps. But I’m no fan of night time chasing and neither is Bill, and knowing the kind of topography that lay to our east once we crossed the river, we dropped our chase at Prairie du Chien and found ourselves a hotel.

After a decent breakfast yesterday morning, we were on the road by noon and headed south. The SPC showed a moderate risk for a large area extending from Iowa and Missouri east across the corn belt and Great Lakes. With a continuation of yesterday’s huge CAPE and good bulk shear, a widespread severe weather outbreak seemed like a sure bet. However, veering surface winds and unidirectional flow seemed to put the kibosh on chances for tornadoes in all but a few areas to the east, where helicities improved, particularly around 21Z.

As we approached Davenport, Iowa, heading south, we could see towers muscling up along an east-west boundary that transected Illinois south of the I-80 corridor. Catching I-80 east, we could see new cells firing up farther to the south on GR3. With a Kankakee target in the back of our minds, we decided to drop toward Normal on I-39.

By the time we drew near the town, the northernmost storm was showing rotation on the radar. The tower was just to our west, and as we proceeded down the highway, the updraft base came into view, dominated by a well-developed wall cloud.

We headed for an intercept, tracking with the storm until it began to degrade. Meanwhile, another cell to the south was strengthening and beginning to exhibit distinct rotation on SRV, so with the storm we were on mushing out, we abandoned it in favor of the second, rapidly intensifying supercell.

This bad boy had an impressive hail shaft, if hail is what we were actually seeing. Maybe it was just plain old rain with a bit of hail mixed in. The reason I wonder is because of the paucity of hail reports. We got tapped a bit as we closed in, but mostly we just encountered buckets of rain. Whatever the case, the updraft tower with the sunlit precip column was a beautiful sight.

After working our way south of the storm’s rear flank, we proceeded east and finally gained some good, clear views of the business end. Tracking with it from near Urbana through Homer, Fairmount, and Westville toward the Indiana border, we were in a good position to enjoy the structure as the storm went through several cycles.

Just east of Homer, the wall cloud tightened and I could see rapidly circulating cloud tags descending toward the ground. We pulled over to watch. The rotation wasn’t far away–maybe a quarter of a mile–and it appeared to be moving toward us. This was strange as we were southwest of the wall cloud, but you can’t argue with a developing tornado. With the updraft approaching to within a couple hundred yards of us, Bill seemed intent on analyzing why the storm was acting so peculiarly, while I favored beating a hasty retreat and working out the behavioral aspects of storm circulation from a somewhat greater distance. Storm chasing sure has its interesting moments.

No tornado materialized, the storm headed east, and we continued on with it. I noticed a couple of tornado reports from around Fairmount and Westville, but while I suppose it’s possible that there was a brief spinup or two, Bill and I never saw an actual tornado. We did witness a few times when the wall cloud began to torque  pretty intensely, and I sure wouldn’t have wanted to be directly below it.

But from the time we first intercepted it to the point where it finally began to fizzle 120 miles later west of Crawfordsville, Indiana, the storm was outflow-dominant. Never once did we enounter surface inflow, though above ground level, I’m sure inflow was strong. In Bill’s words, the circulation kept reaching toward the ground, looking for something to grab onto, but it never could manage to root and produce a tornado. If we’d had backing winds…if the helicities had been there…I’m sure the storm would have been a potent tornado breeder. It never got its act together in that regard, but I doubt the communities in its path felt terribly disappointed, and from my perspective, the storm provided an interesting chase with some very nice moments.

For sheer structure, the “Danville supercell” was interesting and photogenic, with some nice RFD slots wrapping in, and, toward the end of the storm’s career, with a classic, stack-of-plates mesocyclone that was as nice as anything I’ve ever seen. (Sorry, no photos–the ones I have didn’t turn out well.)

One downside to this chase–and it is a big one–is that somewhere between Homer and US 41, I lost my camcorder. It wasn’t a pricey camcorder; it was a used Sony that I bought from my friend and fellow storm chaser Kurt Hulst. But it has done me good service over the past year, and I hate to think that it is presently sitting out there by the side of some Illinois backroad. What’s even worse is, my video of this chase is in it.

The drive back to Grand Rapids was a long one. I arrived at my apartment around 2:30 a.m. and collapsed. The chase was fun and I think I needed it, but it’s good to be back home with the love of my life, Lisa, whose bright eyes and beautiful smile warm my heart wherever I travel.