Tushka Culmination

April 16, 2011 by · 2 Comments
Filed under: Summary 

Southeastern Oklahoma, 14 April 11

SHORT: 3 supercells intercepted in SE OK, likely end of Tushka tornado witnessed after navigating damage.


Ryan Jewell, Jaret Rogers and I left Norman after working the day shift, headed SE toward Ada to get ahead of the supercell that already had crossed I-35 near Davis. Vigorous convection had gone up just E of Norman too. We eschewed that option completely while E of Lexington, given that it was heading into an environment of weaker shear and buoyancy than farther S, and had messy radar structures and mergers happening by then.

Alas, so did the old Arbuckles storm, by the time we saw its inflow region, looking NW from near Stonewall. We had beaten the hail core through Ada by just a few minutes, and took the time to marvel at the turquoise color of the wrapping precip and the long tail cloud. Motion into the mesocyclone region was really fast, inflow screaming from the SE; but mergers with other cells to its S had rendered the supercell, still with an intense mesocyclone, a garishly greenish HP stormzilla.

Two more supercells beckoned to our SW, the first headed for the area between Tupelo and Clarita, and easy to intercept. The storm had a great reflectivity hook, and was TOR-warned; but the low-level velocity structure didn’t look particularly vigorous on radar. Visually, as seen from Clarita (looking WNW), the convective structure was very robust, the base far less precip-infested than the Ada/Stonewall storm. Still, it had a long, scuddy rear-flank gust front, with similar scud drifting about under the putative mesocyclone region. A broad, ragged, very low-hanging, but only weakly rotating wall cloud formed, then fell apart. Not too impressed, we didn’t longer longer, and made haste down OK-48 through Coleman, to OK-22 and westward after the southernmost (anchor) storm near Tishomingo.

We arrived within sight of the storm’s base just a tad late to see the Tishomingo tornado, having this NW-looking view of two wall-cloud regions as the storm moved close to Milburn. The nearer (dark) one fell mercy to the rear-flank downdraft wrapping around the more distant, northern, older, and occluded meso near Milburn (brightened by clear-slot light in this later shot). Here we met and chatted for a spell with Ashton, who later ended up in the damage track of the Tushka tornado very near us as well.

The near (southern) meso thus undercut, we headed N to get a closer look at the circulation near Milburn, but it too was weakening. A wrong turn in Milburn led us to some knobby and often partly broken hail up to 2-1/4 inches in diameter, which we photographed before heading the correct way out of town. We zigzagged from Milburn to Coleman, getting close to the storm’s back edge of the re-intensifying supercell’s hook region. We considered an unmarked road to the east, through Boggy Depot, but rejected it as unsafe, given its unsavory look on the road map, and its precarious position slightly N of astern with respect to the new mesocyclone area. Take that road, we knew, and huge hail wrapping around the backside of a hook echo would be a sure fate.
Instead we busted S back to OK-22 and E to US-75, then N past Caney, arriving to see a mesocyclone with dark, amorphous murk beneath moving past the road in the distance.

Not yet knowing that a tornado was somewhere within that murk, we proceeded NNE up US-75 into Tushka, unaware at first of the intensity of the damage until we had gotten irreversibly into it, embedded in a stream of slow-moving traffic. Broken and uprooted trees appeared on both sides of the big roadway, becoming more numerous in the first mile or two, along with assorted sheet metal, pieces of wood, broken road signs and other variegated flotsam. The blended scent of shredded vegetation, split green wood and rain deeply saturated the air, a unique aggregate aroma I’ve experienced only amid fresh tornado damage.

Right after we drove several feet safely beneath some low-hanging power lines, an adjoining tractor-trailer rig hit them…and kept going full speed! It busted at least three power lines, yanked down a power pole that still had been standing, and may have dragged another already downed pole a short distance. I suspect one of my most abiding memories of this chase will be the furious, staccato “THWAP THWAP THWAP” noises as the cables snapped just behind and next to us. We were aghast that the driver would just plow right through low-hanging power cables, snap them mercilessly, and keep on truckin! I guess he had places to be.

Even within a few minutes after the tornado, plenty of police and other first-responders already were arriving or there. We saw several vehicles flipped asunder, as we navigated around whole trees and large debris on the road; and every overturned vehicle I could see either had no one inside, or at least one person standing next to it. Under those circumstances, and mired the plodding traffic, the best move was to get through the mess safely and expeditiously as possible, and get out of the way of those who needed to be there. It reminded me eerily of coming into the damage swath along I-44 right behind the (also rain-wrapped) Catoosa F4 of 24 April 93. As we entered Atoka, the damage lightened; though we could see more off to the east.

With several miles of damage along the highway, the tornado obviously was fairly wide, even if not exceptionally violent, and took a very oblique path with respect to the road. Even in the deepening twilight, now quite dim under all that storm-cloud cover, we still could see rapid scud motions from left to right above the road (NNE of us), wrapping back around an unseen mesocirculation center to our NE. From Ryan’s I-Phone radar, we figured the mesocyclone (and temporarily, the storm as a whole) had taken a left hook toward the NE, with a new occlusion forming farther downshear. As it turns out, Rich confirmed this for us while we were still in the damage, calling him to report it just in case none of the other hundreds of people had. He also let us know that the mesocyclone was narrowing and perhaps even crossing back over the road as it veered leftward.

Lo and behold, right then we saw a power flash to our NNE, slightly leftward of the road, near Stringtown. Within a minute or two, a ghostly, dim but still very apparent cloud cylinder emerged from the wrapping precip, right in the direction of that power flash. The cloud column, whose bottom was obscured by a terrain ridge, contorted and gyrated wildly, with a ragged coil or helix of scud pulling around the near side shortly before it fell apart. The previous volume scan showed the narrowing couplet in that spot, and the next had it dissipated.

I am now convinced that was the deeply-occluded demise of the Tushka tornado near Stringtown, kicking back out of the rear of the precip-filled area (as I’ve seen a few times before). This is based on Rich’s real-time descriptions of the meso occlusion process on radar, my own post-event radar review, the path/timing of the old occlusion relative to our position N of Atoka, what has been documented of the path so far, and of course that wildly morphing cloud cylinder near where we just had seen a power flash. All things considered, not very satisfying. It’s ironic that the best view of the tornado (Gabe’s, while in some gigantic hail) was from the WNW–the angle we chose not to approach when we were just behind the storm in Coleman.

After the meso died, it was dark; and we found ourselves in a quandary. Dense cores kept crossing US-69 to the NNE, the NW route to Ada (US-75/OK-3) was blocked by a supercell, another supercell was back near Wapanucka headed for Atoka, and miles of tornado damage lined US-75/69 to our S. Solution? Eat. Also, sit down and plan some escape strategy.

At the Subway in north Atoka (an undamaged area), we heard of a triage setup elsewhere in town–the first sign that some casualties had happened. This was bad news indeed. [We didn’t hear of the two fatalities (elderly sisters) until after returning to Norman.] The next TOR polygon for the supercell to our W included Atoka; so the already frazzled employees started locking up to take shelter.

We finished eating out in the vehicle, as the supercell to our W weakened and passed just to the NW. The door out of the area now opened, we then headed home, listening to a combination of Metallica, Slayer, Iron Maiden and Pantera on Ryan’s phone to just wind down a little.

Meteorologically, our forecasting and pre-storm conceptualization was reasonably good. The only part that didn’t work out as well as I like was the large number of left splits and close-proximity cells that made storm modes messier than the orthogonal deep -shear vectors would indicate. Smaller early hodographs with some negative SRH probably contributed to that, along with a nearly simultaneous dispersion of CINH all up and down the area just E of the dryline, from the Red River to the KS border.