Sunday, April 26, 2009 (Western OK, 400 mi.)


A high risk in Choke-lahoma? I think everyone can guess how this one turned out without any hints.

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The setup appeared analagous to 2007-05-05 in several respects: (a) strong flow at all levels of the atmopshere, (b) fairly meridional winds aloft, yielding only modest directional shear, (c) rich boundary-layer moisture already in place prior to the event, leading to uncapped SBCAPE values >2000 J/kg by mid-morning, and (d) repeat initiation expected through the course of the day along a NNE-SSW oriented dryline. There were two primary differences that I noted: (a) boundary-layer moisture was not quite as impressive this time, and (b) a slightly backing-with-height wind profile in the 500 mb-250 mb layer led to an S-shaped hodograph, whereas the 2007-05-05 event featured (modest) veering-with-height throughout the troposphere. And this time, the focal point for dryline convection would be western OK, rather than western and central KS.

I went to bed the night before not even sure I wanted to chase, despite the extremely aggressive SWODY2 issued the previous afternoon (which mentioned a possible "tornado outbreak" across much of OK). The short-term models were unanimous in depicting an uber-messy situation, with convection initiating up and down the dryline fairly early in the day. It seemed the setup was right on the borderline between an afternoon tornado outbreak via quasi-discrete supercells vs. just a plain old-fashioned squall line or series of line segments. The best case chasing scenario would be something similar to 2007-05-05, a day on which training storm motions, cirrus, and very deep moisture severely restricted visibility, but a few good tornadoes were captured by other chasers nonetheless.

Another unfortunate similarity to 2007-05-05 was that Brandon, Bryan and I got very little sleep the night before, having chased the previous day in both cases (with disappointing results both times, but there sure ain't anything unique about that). We made a groggy departure from Norman sometime around 10:30-11:00am. Right before getting on I-35, I pulled into a gas station to top off and look at the latest data. First I pulled up the radar image from KFDR, and just about decided to turn around and head home when I saw the absolute mess of convection overspreading the TX Panhandle under an initial shortwave. Then I load SPC and see an MCD announcing the forthcoming upgrade to categorical HIGH risk for western OK at 1630 UTC. I just laughed (after cursing a few times, probably). There was obviously no way we could sit this one out, but I was already practically dreading going through the motions of the day.

Heading W on I-40 once more, we only made it as far as Weatherford before the first PDS Tornado Watch was issued, and an intensifying supercell to our SW soon became tornado warned (it's still not even noon at this point, mind you). Though it's incredibly hard to get excited about chasing a supercell during the morning hours, we figured we had little to lose, as the only real hope for the day hinged on a second wave of supercells initiating on the dryline much later in the afternoon after this first batch cleared out. We dropped S from Clinton and spent about an hour dinking around with this teaser storm in Washita Co. before letting it blast N past us at I-40, as it obviously had no hope of tornadoing.

Looking back, I suppose pursuing that initial storm really did bite us, in that it set in motion the chain of events that would lead to our first (but certainly not last) heartbreaking screw-up of 2009. When we let the storm go, we were just a few miles S of Clinton. We knew it would likely be several hours before any secondary dryline initiation began, so there was no rush to go anywhere in particular, and we were starving. So we end up heading to Braums in Clinton, where we camp out for the next couple hours waiting for said second round. Elk City would have been just as good a spot to eat and then play the waiting game - and had we not left I-40 to bite on the morning garbage, we may well have ended up there - but as it was, pure laziness (and the fact that deep-layer and low-level shear improved slightly with eastward extent) made sitting tight in Clinton seem a more attractive option.

I'm not sure there was ever much of a pronounced "lull" in storm initiation, as several new cells continued developing over the eastern TX Panhandle during the early- to mid-afternoon. At some point, one of the many strung-out looking storms - this one near Wheeler, TX - began to dominate its local environment and showed some broad rotation on radar. Time to head W, then, right? Nah, that would mean we actually see something for once. Most of southwest OK (S of I-40) had cleared out nicely relative to the area farther N, and shear profiles appeared just as favorable down there, so we decided waiting 20 or 30 minutes to see if the Wheeler storm really meant business was prudent, before abandoning a location that seemed ideal for anything developing in the boiling airmass around the CSM-LTS-CDS area. Long story short, that 20 to 30 minutes of hesitation corresponded to how late we ended up being to the Wheeler-Roll-Vici storm after it produced the only tornadoes of the day in OK. To hear the reports coming in while watching this strung-out piece of crap on radar was pretty much unreal, given that numerous other elongated supercells would develop through the afternoon and evening and completely fail to do anything of significance.

Once we arrived in Vici to find the storm which had just put on the show of the year (so far) for every other chaser on the Plains turning to outflow-dominant garbage, we quickly resolved to fly S to new development moving into the LTS-LAW-CHK area from the Red River. A real long shot, but really, there was not much else we could do if we wanted a chance at redemption. Well, the good news is that we didn't miss anything of significance during the 90-minute trip down to intercept the easternmost cell near Cordell. On the other hand, these already crappy cells had about half an hour before they congealed into a large mass of stratiform rain. That's right: it's about 8pm now, the I-35 corridor of OK is under its first HIGH risk in five years (with MCD's decrying "high confidence" that a "cluster of tornadic supercells" would evolve between WWR and SPS), and we begin the drive home from Caddo Co. through a mass of drenching rain that would seem uneventful even in January. Was this any real surprise? Of course not. There was really never much doubt in my mind what kind of chase day a HIGH risk in OK would yield. It just would have been nice not to watch hundreds of other chasers find the "needle in the haystack" in Roger Mills Co. that we so skillfully avoided, I guess.