14 April 2011: No guts, no gustnadoes

500 mb forecast heights for 00 UTC on 15 April 2011

500 mb forecast heights for 00 UTC on 15 April 2011

I’ll reveal upfront that we didn’t catch any tornadoes on Thursday. The atmosphere decided to skunk us at every turn, failing to produce tornadoes in our target storms, then proceeding to spawn tornadoes minutes after we bailed for other targets.

The day started out with great anticipation. A negatively-tilted trough, along with other favorable ingredients, had appeared in model runs for several consecutive days. Originally, the prospective target was the eastern Oklahoma-Kansas border, around Bartlesville. We’d already arranged a three-car caravan to go chasing, including several new/guest chasers, thinking the odds were pretty good that we could bag them a first tornado.

About 24 hours before chase time, it became clear that the trough was digging farther south than originally thought, so we shifted our target south into eastern Oklahoma, where SPC had delineated a moderate risk area with extensive discussion about favorable conditions for supercells all along the dryline. Concerns about lack of low-level moisture return were allayed by mid-60s dewpoints spread across eastern Oklahoma (as seen by the Mesonet) on Thursday morning, and a strong signal appeared in both the NSSL WRF and HRRR models for isolated supercellular convection in eastern Oklahoma, south of I-40. In the meantime, the warm sector north of the Kansas border looked more and more like an uncapped mess, so we decided to eliminate it from our target.

Our caravan departed Norman just after lunchtime, stopping along I-40 north of Seminole as convective towers began to bubble all along the dryline. The “tail-end Charlie” storm near Atoka, OK, about 60 miles to our south, quickly became dominant. However, we were reluctant to blast south after it, because it would have meant committing to a storm that would certainly move into difficult, forested, hilly terrain, while further eliminating the northeast quadrant of Oklahoma from our target area, where other storms with wall cloud and funnel cloud reports were already occurring.

GRLevel 3 display at 1638

Dan's GR3 display at 4:38 p.m.

We decided to wait for a cell that developed immediately to our southwest. For a while, it seemed like a good choice. This “middle” storm gradually gained strength and assumed supercell shape on radar. It had good separation from the storms to its south, which raised our hopes for uncontaminated inflow. However, I noticed that just about every blip on the KTLX radar had a supercell shape to it – an indication that the local atmosphere was almost uncapped, that convection was likely to fire up everywhere around us, and that outflow boundary and storm-storm interaction might prevent a single storm from becoming dominant. We decided to sit tight, preach patience, and wait for our nearest cluster of storms to get its act together.

Wall cloud north of Okemah, OK

Brief wall cloud north of Okemah, OK at 6:17 p.m.

When one storm in our cluster finally did become dominant, we proceeded to chase it north of Seminole, then abandoned it as it gusted out and another cell to its southwest began to grow. Of course, just a few minutes after we departed our original target storm, GR3 flashed a tornado report from a credible chaser underneath it. D’oh! We watched our second target storm produce and dissipate a couple of wall clouds, then decided to race east on I-40 after our original target storm, now located over Okemah, OK. We easily caught up with it again, and watched for a few minutes as it, too, generated and dissipated a wall cloud with a clear slot, but refused to complete the display and produce a tornado.

As we zigzagged north and east through Morris, OK, nickel-sized hail pelted our caravan. It didn’t make us feel much better that the Atoka storm, well out of our reach to the south, was leaving a trail of tornado reports in its wake. As we passed the wind profiler station near Haskell, OK, its measured wind profiles indicated a weakness in the hodograph between 1 and 3 km above the surface – a possible clue as to why these storms seemed almost incapable of generating persistent low-level rotation. We eventually called off the chase after dark, just north of the town of Wagoner, east of Tulsa. We were treated to some spectacular ground-to-cloud lightning, a consolation prize of sorts, on the drive home.

Tornadoes to the north, tornadoes to the south. Guess where we were?

Tornadoes to the north, tornadoes to the south. Guess where we were?

Yesterday stung more than I expected it to. It was a day that reminds me how much I still have to learn about storms. A group of experienced chasers made near-unanimous decisions that probably would have paid off in most situations. In the end, our decision to avoid the difficult terrain east of Ardmore probably cost us a glimpse of the Tushka tornado, but at the same time, I know of some people who did commit to that storm and still didn’t see a thing, thanks to trees (both standing and fallen), and the notorious terrain that compelled VORTEX2’s organizers to cut a chunk of SE OK out of their operating domain. But, no guts, no glory.

For those who are curious what we missed, I’ll link to this video shot by our friend Gabe G. and his chase partners.

Unfortunately, this tornado caused two fatalities, numerous injuries, and extensive damage in Tushka, OK. In light of that, our bust chase seems pretty trivial.

To their credit, our guest chasers were all very good sports about the situation. A couple of them can’t wait for another chance to chase, and it looks like there are, indeed, other opportunities peeking over the horizon.