September 16, 2006 | Tornadic Supercell in Southeast SD and Southwest MN

September 16, 2006 | Tornadic Supercell in Southeast SD and Southwest MN
All photos © Copyright 2006 Matt Ziebell

On the heels of a great chase the day prior, today's setup looked even better thanks to mid/upper 60 degree dewpoints as far north as eastern SD! I drove north from York, NE to the SD border and watched as the Cu field slowly deepened. Some better growth shown here was popping off to my east, so I shot northeast to keep a reasonable distance with it in case it developed any further. Note: this was the nucleus for what would become the I-90 tornadic supercell.

Now east of Armour, SD and bargaining a shot on the east side of this rapidly developing Cb near Parkston, SD. It had just gone SVR after this and was moving along briskly to the northeast.

I'm now east of Parkston looking at a linear updraft base with a fast moving shelf cloud. Oddly, I never heard any thunder at all from this cell despite a good rear flank downdraft loaded with precip. The updraft on the right was eroding fast and I was really getting disappointed with its behavior. To my southwest was a young Cb with a laminar updraft base, so I stayed in place to monitor this new storm's trends.

Here's the new Cb to my SW that was obviously rotating from early on. It has already split here and I had high hopes for it assuming it would move along the Parkston storm's outflow boundary.

A closer view of the splitting updrafts--much more impressive looking than the Parkston storm now to my north.

The right split storm quickly widened out and looked very promising at this point. Well my anticipation was crushed only about ten minutes later as the entire updraft softened and died. I can only assume this cell crossed over the Parkston storm's outflow.

Now looking northeast as the Parkston storm has improved significantly. Crap, now I have to punch ahead of it again!

While driving east and north to get towards I-90, a tornado warning was issued for this storm only to be followed by a report of a 1/4mi wide tornado near I-90 (note: unsure why spotters exaggerated the tornado's size as it was never this wide per damage surveys).
I was quite upset with myself for having dismissed this storm so early on in favor of that sucker of a rotating storm further southwest, but I remained focused and continued zig-zagging NEward while remaining ~5-8mi from the tornado for most of the drive.

Here I'm south of Salem near I-90 passing across some minor tornado damage (trimmed trees and downed power pole and lines). Everyone pulled over was okay, so I kept moving.

It took a LONG time just to get ahead of this tornadic supercell to view the meso. While approaching Pipestone, MN I observed a brief rope funnel underneath the flanking line and shelf cloud boundary, but the video is pretty crummy and not worth posting any grabs. I continued north and east of Pipestone where I finally got a view of the meso which revealed a rather stout funnel shown on the left. This funnel lasted for a couple minutes before fizzling and was the one reported west of Ruthton, MN. Another funnel quickly developed just southeast of this much closer to me and instead of driving any closer, I yielded it the right of way to cross the road.

Rotating wall cloud and dissipating funnel on left getting ready to cross HWY 23 near Ruthton, MN.

The supercell was now looking very disorganized, so I opted to head southwest towards more redevelopment. While en route, this compact rotating storm developed northeast of Pipestone and proceeded to show off a nice clear slot. It sure looked good for a while, but I aborted it in favor a large supercell west of Pipestone.

Looking west at the larger TOR warned supercell. I can only assume this was the large rotating wall cloud being reported at the time NNW of Pipestone by local spotters.

A persistent compact lowering was again visible to my west close to a rear flank notch, but I couldn't ID rotation. At this time, the supercell's outflow was slowly beginning to dominate and terminate the updraft.

A distant supercell at sunset as viewed from southeast of Brookings, SD.

Overall, despite having missed today's most photographed tornadoes by only a few miles, I still enjoyed this chase very much. With a year like 2006, I've pondered the following question several times: If there was no such phenomenon as a tornado, would I still chase? The answer, though sluggish, has always been yes. To me, tornadoes are the cherry on the fudge sundae. There's so much more to a storm chase than just this one event. I get great satisfaction from making a good forecast, documenting storm structure, seeing small towns, feeling a stiff humid wind, and most of all being away from work. Road construction, long drives, fast food, forecast busts and high gas prices can't even begin to detract from that. As a testament to this, I drove 3641 miles round-trip for this two day chase setup which I'd gladly do again in a heartbeat!

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