At Long Last: Birthday Tornadoes

May 31, 2011 by · Comments Off on At Long Last: Birthday Tornadoes
Filed under: Summary 

Hickory and Ada OK
21 May 11

Prologue:

This was my birthday. I never have seen a tornado on this date before this year, despite the seemingly ideal time of year for them.

Hold on! Tornado climatology isn’t always how it may seem. For strange cosmic reasons that shall remain a cryptic mystery, that date (green in the graph below) also is an inexplicable and pronounced low-day for tornadoes in the U.S. during this time of year, as shown by Chuck Doswell in one of his research papers published in the Electronic Journal of Severe Storms Meteorology.

Click to open an enlarged version:

The Intercept:
Elke and I headed S towards the northern rim of vigorous return-flow moisture near the Red River, followed by a unique chase team consisting of David Fogel, his cousins Samara and Ellie, and Ellie’s friend Ella, and of course DF’s equine-sized Leonberger dog, Porthos. [Note: This meant I was chasing with Elke, Ella and Ellie…good times!] Ellie and Ella were first-time chasers this day, giving me hope for some “rookie luck” to overcome my “birthday curse”.

Our target area was southern OK an north TX just E of the dryline, and we settled for the middle: The Red River, heading to GVT to fuel up and await nearby development near the northern nose of the most robust return-flow moisture. On the way down, messy supercells were evident in central TX, well S and Sw of the Metroplex and out of the target area; while a discrete storm rapidly intensified just SW of FTW. A convergence zone was evident in reflectivity imagery extending N from the FTW storm past ADM. This was our hot zone for hot action.

Not wanting to intercept a storm through the Metroplex if we could help it, we held firm at GVT awaiting closer development. That move paid off; as the FTW storm quickly (and rather inexplicably, given the strong buoyancy) perished.

After fueling and getting some technical difficulties fixed with DF’s onboard electronics, we waited a few miles N of town near I-35, admiring wildflowers and convective towers–yes, newly developed moist updrafts to our near WSW and more distant N. The northern towers, even through haze rendered by smoke from Yucatan crop-burning, looked healthier and began glaciating, as viewed across the verdant North Texas savanna. We had a storm to target, brother.

As we pulled onto the I-35 slab and headed N, strong reflectivity echoes started to appear NW of ADM. Those developed quickly into a strong echo, already resembling a supercell by the time we exited the slab and headed E on OK-53. Intense towers rolled up into the back side of the storm with fantastic buoyant force, as seen looking NE from W of Gene Autry.

Zigzagging E and N toward Sulphur, we met the first hilltop base view just in time to view a funnel suspended from an older, occluded mesocyclone to our NW (and W of town). By the time I could pull over safely, the rotation already weakened, the funnel more ragged and not as low, the clear slot cutting well around the cloud-base mesocyclone area.

Focus shifted to a newer area of cloud-base rotation to the E. The storm already was tornado-warned and had been for some time. That appeared justified. This supercell was moving into a very moist, low-LCL air mass with big (and growing) 0-1 km hodographs. This already was the most promising storm I had seen on a birthday, despite some unquestionable jackassery that ensued while viewing the newer mesocyclone area. None of the scuddy, rotating lowerings to our NNE (just E of Sulphur) could tighten up much, and the storm was getting away.

We needed to reposition, despite the lack of great vantages in that hilly and intermittently forested part of the state. Haze clearly was a problem too, and I knew we needed to be close to get better contrast. Before that area of storm-scale rotation could cycle back up, we headed through town. Our bright-eyed, twentysomething supercellular newbies from New Jersey, Ellie and Ella, got serenaded by the stereophonic wail of the Sulphur sirens, offering them an ominously palpable reminder of the menacing side of springtime in Oklahoma.

About halfway E on OK-7 to OK-1, the organization improved, all right. Obligingly, the storm that had been behaving itself during our relocation grew a very broad, extensive updraft base–all of which was rotating, and rather rapidly. Within the tumultuous gyre, every lowering was spinning in its own right, the whole system a seething, cloud-base cauldron of eddies and whirls that defied ready classification. We stopped 3 SSW of Hickory (and 1 W of the OK-1 intersection) to watch its merry-go-round of distinct funnels, shallow and bowl-shaped lowerings, and at least one brief tornado.

Some vortices were more than two miles apart, others adjacent. Where is the cutoff between a broad, multiple-vortex, weakly tornadic circulation, and a multiple-funnel (or multiple-tornado) area of storm-scale rotation? This thoroughly fascinating process unfolding to our NW through N blurred the lines between any such distinctions on the spectrum of atmospheric vortices. Sometimes, it’s just not as simple as categorically declaring tornado or not!

Two of the longer-lasting, lowest-extending condensation funnels (middle and left here, looking NW) initially developed apart at 1924 CDT, within the same mesocyclone. The eastern (right) funnel retrograded almost magnetically toward the western one, intertwining with it as in a seductive love dance. The combined condensation vortex then became more laminar, less scuddy, more wavy, and produced a brief, faint puff of dust beneath (deep crop-n-zoom/enhancement), in an area of very wet ground.

By 1926, the brief tornado was gone, the area of cloud-base rotation (at left in this shot) that had hosted the small, blended tornado vortex weakened. Did you notice anything to the slightly more distant right (NNW) in the last photo? Lo and behold, another area of rotation took shape to its NNE, itself offering a ragged, conical funnel that extended more than halfway down by 1927 CDT. If this was a tornado (couldn’t determine via enhancement or independent eyewitnesses), it was separate from the other, a circulation within a circulation within a circulation. These were far from the only funnels in the storm-scale gyre in just a 10-minute span. What a gloriously complicated mess!

The broader mesocyclone soon began tightening, and we needed to get E and N again to close in for more unambiguous tornado potential. In the process, we crossed a spot of infamy–the very railroad crossing where an agonizingly slow-moving train halted John Hart and I after we saw the distant Hickory tornado of 11 May 1992. That train 19 years ago seemed to go on forever, as the supercell got away, wrapped rain around its SW hook, and produced a multivortex F4 tornado just out of sight. Today, the tracks were clear and such agony didn’t befall us. The same road we couldn’t take way back then was open for business–right here, right now.

We turned NNE on OK-1 and drove almost under the rim of a (by now) very strongly rotating and more classical mesocyclone, stopping at a spot 1.5 SE Hickory when a broad cone funnel appeared about a mile to our NE. At 1934 CDT, a brief filament of whirling condensation rocketed up from the ground beneath the cone as I was exiting the vehicle, and before I could shoot…tornado! The condensation cone soon drew lower. Sinuous, partly translucent vortex filaments materialized beneath and coiled about one another, vaporous marionettes twirled by their tornadic puppet master. By 1927, the cone retreated to a smooth cloud-base bowl, and no vortices or debris could be seen beneath.

The mesocyclone began retreating NE, so we had to zigzag E and N to maintain view as it reorganized, retreated NNE somewhat, cut a deep clear slot, and intensified again. Heading E on unmarked road “E1700” 5 E of Hickory (a variably surfaced path of gravel, dirt and crumbling, antique pavement), we were very fortunate to find another high, relatively unobstructed vantage to our NNW and N.

Just in time, too…the mesocyclone cut a deep clear slot and began twirling funnels beneath with fervor (deeply enhanced crop). For a brief interlude, the spinning cloud mass dipped its southwestern margins into golden beams of sunshine, fluidly swirling together the concepts of atmospheric violence and beauty.

The circulation seemed to plant itself on the earth, chunks of scud forming right down to the ground, ripping across the surface at tornadic speeds, interspersed with intermittent but unmistakable suction vortices–one after another, none lasting more than a few seconds, but collectively, too many to count. This was a very low, humid, multiple-vortex carousel. Sometimes two vortices could be seen interacting while scud and/or suction spots whizzed through other areas of the magnificent maelstrom.

[Some described this tornadic stage as a “wedge”, but the condensation was too ragged, sparse and ephemeral to call it that. Still, if viewed with any blockage by trees or terrain, I can see how such a mistaken description could be made.]

The last evidence of a tornado was at 1953; thereafter the cloud base rotated much more weakly and rose in height. By now, we knew of the larger, newer and stronger supercell W of Ada, but the clearest path to it up US-377 still was blocked by our weakening (yet still potentially hail-bearing) storm.

After letting that supercell pass across the highway, we had a smooth trip to Ada, barely in time to see a conical lowering below the horizon (turned out to be the end stage of its last tornado at 2035 CDT) while still driving. By the time we found a place to stop, a small and ragged funnel remained. No matter, we could marvel at the spectacular storm structure spreading across the western sky. As this storm moved NW of Ada and began weakening, assorted precip shafts cascaded from the cloud base near low-hanging scud chunks, likely yielding any remaining “funnel” or “tornado” reports.

The short but happy drive back to Norman led to a delicious dinner, steak and shrimp for the menfolk, whatever the ladies wanted, kibbles for Porthos out in their vehicle, all in a festive celebration of a fantastic storm-observing day (and for me, the clinching win on the restaurant TVs that sent the Mavericks to the NBA finals). Birthday tornadoes that didn’t hurt anybody, great storm structure, Mavs clinch a playoff series…a great, great day indeed!

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.

LONG:

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.

The US-412 Supercell

April 9, 2011 by · Comments Off on The US-412 Supercell
Filed under: Summary 

Enid/Garber OK
8 Apr 11

SHORT: Modest, yet enjoyable supercell observed east of Enid that developed in the warm sector (not on the dryline).

LONG:

The initial thinking from prior days, and early on this one, was that a dryline storm could fire somewhere over western OK in a zone of intense heating and mixing that would overcome strong EML-based capping, and move eastward into more moist air for a short time amidst an ambient kinematic profile most definitely suitable for storm-scale rotation. Instead, we ended up with one warm-sector supercell out of several! Here’s how…

A persistent zone of northward-moving, gradually deepening cumuli, corresponding to a zone of intense heating and mixing east of the dryline, formed during early-mid afternoon over NW TX near Vernon, and also, in an area of weak surface wind-shift and mass convergence as evident in both plotted charts and objective analyses. This immediately caught our attention (Corey M, Rich T and I); and we began to ponder this as a potential storm genesis source. The later it went, the farther N it would go; as the combined surface and satellite feature was moving N across I-40 and into the Kingfisher area by the time we left. After Rich picked up his son from school; we all met at Battlestar Norman and departed for El Reno via the Highway 9/turnpike bypass, intending to head N on US-81 from El Reno.

While near the former Kelvin’s Corner, we spotted turkey towers with glaciation to the NW, a good sign of deep ascent that encouraged us onward. VIS imagery showed a boomerang-shaped field of deeply enhanced Cu, much of which we couldn’t see visually from a distance because of smoke-related boundary-layer haze. The inflection point of this boomerang was moving N from the Kingfisher area; so we headed that way. That’s where the first echo–the eventual Enid storm–erupted while we were approaching Kingfisher.

We cruised up to Hennessey as the nascent supercell grew, towers rolling up its near (SW) flank and backshearing. The storm lost some organization on radar during an initial storm split; but its updraft towers till looked robust visually. In accordance with that encouraging sign, the right-split recovered nicely from the initial body-blow as we maneuvered E on OK-51 and N on OK-74 toward Covington.

Our initial views of the underside from SW of Covington (no photos…stupidly, I left the camera in the back of Rich’s vehicle while we were driving) revealed a high, somewhat disorganized base. As we approached from the S, the eastern portion of the updraft region began re-ingesting a partial mix of rain-cooled air. Huge chunks of scud formed and rose, appending themselves together into a tall, ragged wall cloud that rotated slowly, assuming a triangular shape for a short time. At one point, the point of the triangle lowered about 4/5 to the ground from a very high ambient cloud base; but rotation was slow at best, and no dust or debris could be spotted beneath. This seemed to be the “almost a tornado” phase some chasers described.

As we reached 412 and turned E, the storm was in its best-organized phase–peak midlevel rotation in SRM displays and that ragged, occasionally low-hanging and pointed wall cloud with obvious cyclonic shear. The meso wasn’t strong enough to pull a great deal of precip around yet. As we continued E on 412 and got abeam of the circulation, a lot of the scud evaporated, as if the wall cloud were disrobing to reveal a peculiar, tilted but mostly horizontal cloud vortex. This feature narrowed into a skinny, nearly horizontal funnel, somewhat bent, and way above the ground. We didn’t deem this an imminent tornado threat.

By the time we pulled over at an optimum vantage, and I got out the camera, the laminar, horizontal, funnel-like feature to our N had vanished; and the ragged wall cloud was eroding away to reveal the more ambient, high base again. At this stage, the structure reminded me a bit of the 22 May 7 supercell near St. Peter, KS, but of course, without the tornado! Storm motion slowed down; and we were able to maintain a leisurely pace east on US-412 with a couple of long-lasting stops to observe the supercell’s high but well-structured underside to our N.

The storm attempted a couple of occlusions, including this one with a well-defined downdraft slot and precip cascade, while surface-based inflow still was screaming from the S and buffeting us reasonably well. Soon, however, the inflow calmed a bit, and the storm took on a more laminar, elevated appearance as it approached I-35 (shot looking NNE with CG from the vault region).

As the storm continued to weaken, we bid it a fond farewell, and headed S on I-35 toward home.

This was a fine first chase of the season, a good opportunity to work out some kinks, test new equipment, and re-learn needed lessons (i.e., “Self, you forgetful doofus, keep the damn camera in reach while someone else is driving!”). It was great to get out on the Plains again and watch a supercell–a cathartic release from the psychological imprisonment of a long, cold winter. Even though we are mired in deep drought here in central OK, we bear hopes for at least a few more photogenic supercells within reasonable driving distance the remainder of the season, as prospects for the big events already appear to be displaced far, far away.

« Previous PageNext Page »