November to Remember
Tornadic Supercell in Southwest Oklahoma
7 November 11
SHORT: Intercepted two nontornadic supercells and one tornadic in SW OK. Witnessed multivortex tornado move through wind farm, among others.
LONG: This has been a very fortunate year for me for storm observing, and a rare juxtaposition of a day off with a November chase day offered the promise of icing on the fine tornadic cake that has been 2011.
Pre-storm
For several days, a classical, spring-like, near-dryline supercell setup appeared to be looming…in autumn. Looking at the morning charts and RAOBs, the presence of very nearly surface-based effective inflow parcels even during early-mid morning (using FWD and OUN soundings) reinforced my main concern–the potential for early initiation, maybe too many storms too soon. Otherwise the foci for supercell and tornado potential looked fairly well-defined, the target area compact: approaching, progressive shortwave trough aloft with deep-layer shear strengthening throughout the day, adequate moisture return, backed winds, and enhanced low-level vorticity along an outflow boundary E of a dryline and cold front…all in the southwest OK/NW TX area.
After morning appointments (I try to avoid scheduling any immovable commitments for afternoons even in the “off-season”), visible imagery showed good clearing from the southern tier of OK counties (LTS-FSI) southward, and towers already starting to deepen in the weak CINH even before noon. The deepest warm-sector convection already was forming near 100W (TX/OK border longitude), with other clumps of shallower convection farther ESE over NW TX. Time to head out the door!
Early, non-tornadic supercells
Perhaps I left a little too soon; this is a longstanding bias of mine. Still, I targeted the LTS area via the NE (HBR) instead of E (FSI), in case any decent storm rode up the western fringe of OK and into the baroclinic zone. I’ve had a few successes with early-event tornadic storms tucked in the NW side of a SE-expanding storm regime, and a supercell SW of Mangum was getting larger.
By the time I reached Lone Wolf, on the way toward Mangum, a messy cluster of storms with some banding and supercellular tendencies had formed to the SW (wide-angle). I considered staying near there, and perhaps should have in hindsight, given a few observers’ later reports of a short-lived multivortex tornado with an eventual supercell SW of HBR. Instead, I headed to the western storm, somewhat concerned that my onboard thermometer indicated only the narrowest of slivers of diabatic warming between the HBR cluster and the now tornado-warned Mangum storm.
The western storm came into view NW of Mangum; I parked 2 WSW Brinkman to let the storm move just to my W and N. It was somewhat pretty, but not too promising. An earlier, distant wall cloud had vanished, and the storm looked rather strung-out. A new mesocyclonic cycle yielded a weakly rotating, nice-looking little wall cloud, but it couldn’t tighten up and produce. Moreover, the probability it would was dropping by the minute; inflow air was getting cooler! Naturally, the storm started to weaken.
By this time, a small cell I earlier had noted on radar, S of the Red River and S of FDR, had exploded and was taking on obvious supercellular signatures. I was out of position for anything it would do in the next 1-1.5 hours, and knew it. But I also knew it would have a long potential trek through vorticity-rich air of at least marginal buoyancy, all the way N of the Wichita Mountains, if no other storms erupted to its S or SE. For now and for hours, that southeastern storm would remain unimpeded that way.
I wasted no time in deciding to go toward the FDR storm, but two other supercells were in the way: one just SW of HBR (the early multivortex producer I missed) and the other slightly farther SW, also approaching HBR. My best chance at shooting the gap between these two supercellular obstacles and stay on course for the southeastern storm was to head back through Lone Wolf to HBR, around the northern flank of the southern-middle storm and S of the hook of the northern one (beautiful rainbow scene on their collective W side). I threaded between the two most dense core regions; but the gap was small and I did encounter some small to marginal-severe hail in the southern (nontornadic) HBR storm’s forward flank. Here’s a wide-angle look at the southern-middle storm between HBR and Roosevelt, looking WSW.
Turning S out of HBR, my timing looked barely adequate, and more likely too slow, to reach the FDR storm S of the Wichitas. By now, I already had heard of a couple of tornadoes it had produced; and the storm appeared to be trucking along nicely with a powerful low-tilt velocity signature. Instead of trying to stern-chase it on US-62, only to encounter a road void in the Wichitas, I chose to head E out of Roosevelt, skirt the storm’s northern flank, and wait N of the Slick Hills for the supercell’s business end to come toward me. I knew the massive, E-W oriented Blue Canyon Wind Farm was a couple miles S of OK-19 too, right in the meso’s path, and might provide an interesting foreground for whatever emerged from the rough terrain. It would be my first correct strategic decision all day.
Post-Wichitas phase of tornadic supercell
Heading E from Roosevelt, I could see some of the rear-flank convective wall of the FDR supercell to my S; while a very bright rainbow with secondary accompaniment festooned the fringes of its left-flank precip core. I zigzagged the necessary roads toward the area NE of Saddle Mountain, encountering more mainly sub-severe hail in the tornadic storm’s northern rim. The hook echo was very impressive on radar, when I had any phone data in this reception-deprived area, with one scan of ~100-kt gate-to-gate shear. By now, I was preparing for the possibility of a big tornado coming out of the mountains and through that wind farm.
A fine viewpoint appeared ~5 SW Alden on OK19, with a surprisingly green field of winter wheat leading SW toward the ridge-top wind farm. The mesocyclone’s orbiting rim of cloud-base scud came into view to the SW, circulating at impressive peripheral speeds that I’ve seen only with tornadic settings. The meso was translating directly toward me, but still with plenty of time to spare and a good escape route eastward. Time to rock and roll. Alas, a furious bombardment of close CGs kept me under within the vehicle for several more minutes. A group of unrecognized chasers showed up at the same vantage, standing outside rather unwisely despite the occasional CGs still hitting within hundreds of yards.
Fortunately the electrical attack from above abated fairly quickly, and we all could concentrate again on the approaching mesocyclonic menace. I was very confident a tornado still was lurking beyond the ridge line near Saddle Mountain; and within minutes, that suspicion was confirmed! The visible condensation funnel of the tornado, still beyond the ridge, vanished from obvious view for a minute or two, the visible parts of the cloud base seemingly boiling with furious movements. The tornado reappeared even better. I strongly suspect this was the same tornado as before, given
1. Its temporal and spatial continuity relative to the ambient mesocyclone circulation, and
2. Later TV-chopper videos I’ve seen of the Saddle Mountain tornado, which dissipated right before reaching the wind farm.
A new, strongly rotating wall cloud formed N of the dissipated tornado and over the western part of the wind farm. In fact, its base was so low that the turbine blades extended into the cloud! The new circulation also extended E of the visible wall cloud, which seemed to subsist on recycling of rain-cooled air from the precip wrapping around the N and NW sides of the hook. This fascinating process was about to get more so, and fast.
On the E (left) side of the mesocyclone, slightly displaced from the lowest part of the wall cloud, a multiple-vortex tornado, containing a dominant central condensation tube, developed over the wind farm. This was obviously separate from the earlier tornado. Since some of my home’s power comes from this wind farm, I was hoping against its destruction; in fact, as the tornadic circulation continued to swirl through and around the turbines (wide view and cropped), I saw no clear evidence of damage.
Small suction vortices occasionally formed and pirouetted gracefully among the turbines (wide view and cropped), as the main cone became more sharply defined (wide view and cropped). The entire scene was strange and ironic — a wind farm under siege from the ultimate in “wind power” (wide view and cropped).
Through the whole ordeal, the disabled blades held firm, not budging nor popping loose, despite the undoubtedly intense mechanical stresses. The functional turbines seemed to adjust their alignment (with some lag) to the mesocyclonic wind shift, but of course, couldn’t do so fast enough at tornado-vortex scale. The blades’ rotation speed seemed to remain fairly steady, which fits the purposeful design of such machines to brake the spin rates in order to minimize damage in extreme wind. This certainly qualifies as extreme wind!
A powerful, precip-laden RFD surge hit the tornado, weakening it while sending the remains of the circulation careening ENE through the N side of the wind farm, at an oblique angle. A newer mesocyclone was tightening up rapidly, immediately (just over a mile ) to my SW, so it was time to reposition a tad east. While driving, a glance in the right-side rear-view mirror revealed a new, entirely separate tornado developing as a tall, slender tube. This pretty, partially rain-wrapped tornado (the third for me so far) only lasted a couple of minutes, dissipating as it reached OK-19 near where I had parked before.
This newest mesocirculation, with wrapping rain curtains, shot toward the NNE beyond OK-19. I headed E a little over a mile to OK-58 then N, watching it weaken as it obliquely approached the road to my immediate WNW. The mesocyclone dissipated fast. Still, rain curtains seemed to be moving fairly quickly in assorted directions around me. Frequent glances at the cloud base above revealed strengthening, convergent westerly flow. I soon saw why.
Yet another quick occlusion was about to occur, as another mesocyclone developed a short distance to the E. This was not the optimal position for any storm observer to occupy, so I searched for a good E option that would take me out of the backside of the hook. [Fortunately, the storm continued its trend of producing non-damaging hail with respect to my vehicle.] Now WNW of the new circulation, I turned E on E1380 Road toward “Pine Ridge”, a crossroads with neither a ridge nor pines. The road was reasonably well-drained, alternating between paved and hard-packed gravel with occasional shallow puddles, and was good to go at 50-55 mph in high 4WD.
Right after my turn, a fuzzy cone tornado materialized to the ESE, allowing a brief stop to photograph it before the rear-hook firehose started dousing me. The white smudge in the last shot, below and to the left of the tornado bottom, was a hail splash.
Back on the road again, I carefully approached the mesocyclone and tornado from the W, watching the latter dissipate and the former rotate intensely as it crossed E1390 about a mile away. This circulation moved N, and yet another one (the eventual Ft. Cobb tornado producer) developed just to its E. By now, the storm definitely was translating poleward and speeding up, getting away from me even as I drove the short few miles to my N turn on N2550 at “Pine Ridge”.
Seeing occasional multivortex filaments form under the new circulation (the Ft. Cobb tornado), I stopped briefly to photograph the storm structure with the mesocyclonic cloud base below (deeply enhanced crop-n-zoom). Heading N toward Ft. Cobb, I could see occasional plantings of full ground-cloud condensation; but every one of the 4-5 times I tried to pull over and photograph them, the condensation would go away. Daylight and contrast each grew dimmer also.
After escaping Ft. Cobb, I drew closer to what was left of the circulation near Albert, its cloud base still rotating and low-hanging in the twilight, but obviously weakening. I couldn’t complain much, though, I had found my fifth tornado of the day, a pretty remarkable feat considering some poor tactical decisions early in the afternoon that caused me to miss a fantastic tornado show SW of the Wichita Mountains.
Epilogue
The trip back was mercifully short, as the former FDR-Ft. Cobb supercell got absorbed ingloriously into a building band of storms near Okarche. How often does one arrive home by 7 p.m. after a multi-tornado intercept? Despite what I had missed, these were my latest tornadoes seen in a calendar year, and multiplied by six the sum total of lifetime November tornadoes.
To make the day truly unique, I got to experience an earthquake too. Not long after settling in at the house, a low, thunderous rumble and weak vibrating of the house signaled the magnitude 4.7 aftershock from the Sparks earthquake swarm that had been rattling off and on for several days. I had felt the Oklahoma-record magnitude 5.6 shaker a couple of nights earlier while in a cabin at Greenleaf State Park (my first ever). With multiple earthquakes and tornadoes witnessed in a 3-day span, it was a marvelous time for an earth scientist in Oklahoma. 2011 also has been, by far, my most prolific tornado year.
As with the 20 June tornado-fest in Kansas and Nebraska, I sent an itemized table of tornado times and estimated locations to the WFO, with embedded links to many of the same photos as above. That table includes times, locations and links to the photos. What had been listed as one tornado on coarse-resolution maps, from S of the Wichitas to OK-19, should become three in the final record. The tornado log file is in the public domain, and linked here in MS Excel format, freely accessible for anyone interested.
Clam’s Foot Surfer
Dumas TX and vicinity
12 Jun 10
SHORT: Observed outflow-dominant line E of Dumas, elevated stage of supercell SW of Dumas that hailed over us at dinner.
LONG:
Elke and I began the day with a cold breakfast at our Burlington motel, joined by Chuck and Teresa Robertson, then Matt Crowther and Vince Miller, all of whom also had intercepted the Limon-area supercells the day before. The cold front was surging farther S, faster than forecast the previous day, so we all had to get out of town soon and jaunt down south to the Panhandles. For Chuck and his lovely bride, who live in the northeastern TX Panhandle, it would be a return home, with storms along the way.
After a couple of hours on the road, we stopped to pick up some provisions at the Wal-Mart in Lamar CO. On the way to the rear latrine, I spotted a familiar human form — there was Vince, picking out a shirt in the clothing section! What are the odds? A short chat with him and Matt outside, and we all were back on the road again. We wouldn’t see either of them the remainder of the day. Still, in storm observing, such are the unplanned, chance encounters one can have with familiar old friends and acquaintances.
By the time we got to Boise City OK, storms already were firing along the cold front to our S and SE in the TX Panhandle, with big towers erupting beyond the cool, foggy haze. The most robust of those went through a briefly tornadic supercell phase well before we could get to it, then turned into a large HP mess. We thought about “rounding the corner” on it E of Dumas, but by the time we committed to that plan and got near it, the entire complex had degenerated into this rather amorphous, outflow-spewing mess, all while dumping nearly a foot of rain from train-echoes near Morse.
Another fun serendipity of storm observing is being in the same place twice, hundreds of miles from home, on different days and different storms, in the same season. Such was the case with the last photo, which I took on FM-1060 while less than a hundred yards from where I shot the mesocyclonic merry-go-round E of Dumas the previous month (see You Decide, 18 May 10). We retraced steps from that amazing May day eastward through Stinnett and north a few miles, but without such intense atmospheric results.
While shooting time lapses N of Stinnett, David Hoadley pulled up and chatted with us for awhile in the cool outflow. It’s always a pleasure to see Dave again, as I seem to do about once a season at some random rural pull-off near a storm. Some new cells were trying to fire south of the outflow boundary and W-NW of AMA, so Dave and I agreed that was the only remaining viable target, and parted ways, independently heading the same general direction. Along the way back to Dumas, Elke and I stopped to shoot a couple of peculiar, fascinatingly illuminated and somewhat convective scud formations (first and second).
One longer-lived cell had crossed over the arching outflow boundary SW of Dumas but remained intense on radar, so after grabbing a motel room there, we drove a couple of miles S of town to take an unobstructed look. We still were in cold NE outflow from the massive complex to our NE, and this storm was obviously elevated at the time, exhibiting laminar formations and riding atop an elongated, clam’s-foot cloud formation (wide-angle view looking WSW) as the chill breeze at our backs strengthened further. Ribbed texturing to the main low-cloud band, glowing in twice-reflected, late-afternoon light, formed an uncommon and striking visual backdrop for the wind farm SW of town.
Thinking somewhat erroneously that the storm would remain elevated, we ate dinner in Dumas as it rolled over us, profusely peppering the restaurant windows with a protracted blast of hail near an inch in diameter. I was tempted to run out and grab some hailstones as ice for my drink, though the Moore County Health Department might not have approved of this item on the menu. It turns out that the supercell backbuilt and right-moved, once again getting close to the eastern segment of the curving boundary, and becoming surface-based again to our E, after it left town. We finished supper and headed a few miles SW of Dumas hoping for sunset photography, but with all the various clouds in the way, all we could salvage was some twilight pastels over ripened wheat.
We slept well that night, knowing that the next days’ target would be in the Panhandle also, but not knowing that we would see both a pretty tornado-producing supercell and the largest amount of standing water we’ve ever witnessed on a High Plains storm intercept.