May 1, 2002 Mini-Chase

by John Farley

This one hurts. Due to a meeting I had to attend this afternoon, and things I had to attend to at work, I couldn't get out for a serious chase, but was watching radar to intercept any storms that might crop up nearby. By shortly after noon I was watching a cluster of strong thunderstorms just northwest of the STL area. They were racing east at 40-50 mph, par for the course lately in our area. I just kept working, checking radar and warnings every 10 minutes or so. By a little before 1 p.m. I could see that the strongest storm was a relatively new one at the southwest end of the cluster that had popped up near Alton. Here is a radar image fron about 1 p.m. showing this storm just northwest of Alton, as well as the larger cluster of storms just to its northeast. Figuring that the storm near Alton would move across northern Madison Co. and would have the best inflow of the bunch (all were located just north of the warm front, and were described by SPC as likely elevated), I decided to head north for an intercept.

As I backed out my driveway, I made what turned out to be a crucial mistake. My options were to head north on route 159 from Edwardsville and intercept the storm directly north of town, or head up I-55 one exit to Hamel, then likely poke west. I decided on the former, and that probably cost me a chance to see a tornado. I thought I had plenty of time to intercept the storm, and the driving distance was less this way. As I headed through town, I could see the sky was very dark to the north and northeast, and lighter to the west. Was I making a mistake? Too late now, I was committed to that route.

As I headed north in light rain under stratus and in fog, I could soon see some very low, scuddy cloud base to the west, and dark sky to the northeast. "Sure doesn't look elevated to me," I thought. I poked north under the eastward racing cloud base and hit moderate to heavy rain, but that's it. Not a flash of lightning, and frankly nothing that looked remotelly severe. Bust! Time to get back to work. I shut off the WX radio and turned on KMOX, which usually has decent weather reports. But nothing was happening, or so I thought.

Therefore, was I surprised when I got back in Edwardsville to hear them activate a warning alarm for a TOR warning for Bond County (next county east of Madison!). Then the news guy came on and said semis were overturned at the 35 mile marker of I-55. That is 12 miles north of the Edwardsville exit, right where I would have gone had I gone up I-55 instead of 159. A radar check showed that the storm had quickly developed a nice hook and the rain I had been in was wrapping around the back side of the storm, while a possible tornado dropped very close to where I would have been had I driven up I-55.

Sporadic damage was reported, from Staunton southeast to I-55 and the Livingston area, and continuing SE to Greenville, IL, where a number of businesses and homes were damaged. (6 tornadoes have now been confirmed in the Greenville area; see update below.) Semi trucks were also blown over on I-70 (by two of the tornadoes near Greenville), and a train was derailed near the Madison-Macoupin-Bond Co. intersection, likely by the same event that overturned the trucks on I-55.

This storm did not look potentially tornadic when I left home (see 1 p.m. radar link above), and it had no warning of any kind for the portion of it in Madison Co. when the damage began in northeast Madison Co. It went from an ordinary looking storm to an obvious supercell (see 2 p.m. radar above) in a matter of minutes. When I first wrote this, it was 8:30 p.m., and the storm was still going and still causing tornado warnings somewhere in Kentucky. Even at 11:30 p.m. the storm was still going, but had evloved into an MCS. By then, it was in north-central North Carolina! As this map from SPC shows, this storm caused a near-continuous streak of severe reports from just north of STL to the Tennessee-North Carolina state line.

I blew this because I underestimated how far the storm would move by the time I reached my target location. Probably also underestimated how long it would take to get through Edwardsville. And I could have easily intercepted it had I just headed up I-55 one exit. Lesson learned: With fast-moving storms, don't cut it close! A slightly longer drive to the northeast that yields a tornado is better than a short drive to the north that leaves a bust 10 miles behind the storm! Like I said, this one hurt.

I know some chasers at least got near this storm, because the LSR on the overturned trucks on I-55 said it was reported by a chaser. (Turns out, I later learned, that this report was filed by Chris Novy, who was trying to catch the storm from the north.) Also saw chase reports later from the Flora and St. Elmo, IL areas. Others? I've yet to hear from any chasers who saw any of the several tornadoes this storm produced along its long track.

Preliminary local storms reports on this storm can be found here.

UPDATE May 5 - An NWS damage survey has revealed that this storm produced at least 9 tornadoes in the St. Louis CWA - 6 in the Greenville, IL area (4 F1 and 2 F0) and 3 (all F1) in the Kimmundy, IL area. The St. Louis NWS has posted a summary of the damage survey with tornado track maps here. This damage survey does NOT include damage done in the Staunton-Livingston, IL area, where two semi trucks and a freight train were blown over. I will post additional information as it becomes available.

Total chase distance: about 25 miles.

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