Twin tornadoes: August 13, 2019

What a day. I forced myself to go to sleep early the night before, but in anticipation of the storm chase, I woke up shortly before 2 a.m. and ended up leaving Oklahoma City by 4:30. That gave me enough time to get to northeastern Colorado with about an hour to spare. With prospects of considerable instability (3000+ J/kg CAPE) with 40+ knots of deep layer shear in Colorado, I was cautiously optimistic about what the day would have in store.

I watched the first storm begin to develop in Yuma County early in the afternoon and decided it was best to stay put, even though I toyed with the idea of targeting a cluster of storms coming out of Nebraska. Needless to say, I did not do that.

A pair of storms evolved into supercell structures with prominent wall clouds, to the southwest of Wray. At first, the northern cell looked dominant, but it suddenly withered away, giving way to a more classic-looking supercell to the south. I managed to get back to US-385 just in time to dart west on US-36 for a closer look. I watched a tornado from start to finish, even though I was not particularly close. The rough estimate was that the tornado lasted about 7-8 minutes or so and toward the end, there was about a minute with two tornadoes side-by-side.

The initial (main) tornado began to rope out shortly after its twin lifted. I did not manage to stop for any photos, as it was heavily raining, power lines were in the way and I was hoping to intercept the storm as it moved south. While the video may not be of the highest quality, it does cover the vast majority of the life cycles of the tornadoes.

I chased the storms for a while, but after the initial tornadoes, the setup quickly became messy. I closed in on a rain-wrapped, occluding mesocyclone north of Bethune, but with questionable road conditions and very large hail, I got back south to avoid getting stuck or a busted windshield. It turns out that record large hail (over 4-inches in diameter) was observed near Bethune, so it was probably a good idea that I did not get too close.

It wasn’t much later that the storms started throwing out quite a bit of outflow and the tornado potential decreased. I didn’t get much footage worth sharing, but I noted several gustnadoes and/or quasi-landspouts along surging outflow, but most of these features were relatively short-lived.

The day ended in Sharon Springs, just in time for a mammatus-filled sunset.

For the first time since late May, I saw a tornado and even though I was not particularly close, I cannot pass up a tornado in August. I’ve had better luck chasing in Colorado lately, but I think part of that is from learning from past mistakes. Convection often initiates earlier than guidance suggests and that was the case again today. Even though the CAPE/shear parameter space was very impressive for Colorado, as often happens when there’s large CAPE in Colorado, storm modes became messy fairly quickly.