2012-04-30: LP supercell near Claude, TX

The last week of April saw the arrival of this year’s Windom High School group from southwest Minnesota, consisting of nine enthusiastic, weather-savvy seniors, their teacher, Craig Wolter, and three chaperones. Each year, Craig takes his top ten or so students on a five-day storm chasing trip to Norman, where the students get to visit the NWC and meet and greet with meteorologists there. Craig has a tight itinerary for his students upon arriving in Norman, but it can always be pre-empted by a decent chase setup. As a fellow Minnesotan, I have a soft spot for Craig’s kids, and always try to lead them on at least one chase. If there had been such a program at my high school, I would have killed to get on the trip!

Dan and I were able to take Windom group out on Monday, April 30th, after noticing an enticing setup in the Texas panhandle consisting of a trough encroaching on an outflow boundary from the previous night’s widespread convection. Upon arriving in Memphis, TX, we found convection struggling to initiate along the dryline. We drifted northwest on U.S. Hwy. 287, toward a clump of storms west of Amarillo, intercepting it as it organized into a supercell near Claude, TX. We drove about 2 miles north off of U.S. Hwy. 287 to obtain a clear view to the west.

We were presented with a beautiful, high-contrast LP supercell, and proceeded to point out all the salient features to the students. The high bases didn’t bother us too much, because we knew the Claude storm was drifting east into better moisture, and we expected great things from it once it began to realize the improved buoyancy. As we watched, the Claude storm split right in front of the students, allowing us to narrate the process live. I pointed out a small, cone-shaped lowering just south of the main precipitation shaft on the right-mover. It persisted for three to four minutes, but never extended more than 10% of the distance from cloud to ground.

Meanwhile, we noticed new Cbs to our east, rooted in the deeper moisture. The updrafts on the new towers were crisp and glaciated, so we kept our heads on swivels in case we needed to re-target. The Claude storm dropped a few nickel-and-dime hailstones on us, forcing us to jog east twice along our dirt road in order to keep ahead of the storm. The vault structure grew breathtaking. We were able to enjoy it in relative solitude, without any other chasers blowing clouds of dirt on us. Simply moving a mile or so off the main highway is proving a surprisingly effective way to avoid the hordes. (I think I’m going to require 4WD in my next chase vehicle.)

The Claude, TX supercell eventually became outflow-dominant, so we decided to re-target the next storm to the east (the Hedley, TX storm), whose birth we had witnessed about an hour before. We retraced our route southeast on U.S. Hwy. 287, then went east on TX-203. We thought we would be able to core-punch the Hedley storm without too much trouble as it lifted northeast, then emerge from its forward flank and with a view of the hook to our southwest. However, radar updates showed new storm cells erupting to the south of, then being ingested by, the Hedley storm. These processes interfered with storm consolidation and hook formation, and also resulted in our spending more time in the hail core than we expected, our vehicles pelted with nickels and dimes for nearly 40 minutes.

When we finally did emerge from what should have been the forward flank of our target storm, crossing over the border where TX-203 changed to OK-9, it was dusk. Looking back toward Wellington, TX, we caught glimpses of the hook region to our southwest. Suddenly, Dan commanded me to stop the car, chattering excitedly about a dust cloud. I couldn’t see anything from the driver’s seat, but I stopped at the top of a hill. By the time I got out of the car and fired up my camera, the dust cloud was gone, but I could see the scud finger which had grabbed his attention. My only photo of it is very poor and I had to enhance the hell out of the contrast in order to make it visible. The feature was too brief and ambiguous, the distance too far, and the lighting too poor, for us to conclusively call it a tornado.

We took a rather circuitous route back to Norman via Lawton, attempting to avoid a southward-diving hailer over Hobart, OK. We returned to Norman around 1 a.m.

In the days since this chase, I’ve read an April 30 chase account from Bill Reid, whose Tempest Tour group (including Brian Morganti) was much closer to the ambiguous lowering than we were. Even with his close proximity, he wasn’t certain what to call the feature, and after viewing his video, I can see why. However, he eventually concluded that this dusty spin-up was indeed a tornado. Bill’s a veteran chaser, and if he says it was a tornado, then that’s good enough for me. Based on his account, I was able to report to Craig that his students were no longer tornado virgins!

Update, 2012-05-07: After looking at video from the Tempest Tours group, the NWS office in Amarillo declared our “scud finger” an EF-0 tornado. So, now, it’s officially official!