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.
Junk Storms in Eastern Oklahoma
Dewar to Wainwright OK
22 May 11
SHORT: Agonizingly slow-developing small cell Henryetta-Okemah followed by beefier but disorganized storms same area.
LONG: Once we got awake and organized, the Ozarks of SW MO and far NE OK seemed too far (and too unfriendly terrain-wise). Any nearer target for the day was rather nebulous, given the lack of a sharply defined boundary ahead of, and of strong lift along the Oklahoma segment of the dryline. However, we pulled out of Norman to the sight of towering Cu up and down a SW-NE aligned dryline located to our SSE through NE. Despite the SSW winds to its E, high SRH beckoned in eastern OK; and the dryline’s confluence (and convergence) zone became better evident with time during the afternoon in both clear-air mode reflectivity and VIS satellite imagery.
As the day before, following close behind (but not too close, since I was consuming pork rinds): the Dude, Three Chicks and a Dog chase team. And yes, given that we were headed to eastern OK, it was fitting that I was wearing a cartoonish “EVERYONE LOVES A REDNECK” shirt DF gave me as a birthday gift.
We waited at Ada only a short several minutes before towers erupted into a Cb to our NNE, S of I-40 and E of the dryline. Meanwhile a growing left-mover was charging NE from a splitting process down along the Red River, while the right-mover was dying. With nothing in between, we targeted the cell approaching Henryetta.
On composite reflectivity, the storm seemed to level off at under 50 dBZ for well over an hour, despite a healthy (if episodic) chimney of towers shooting forth into its anvil. With MLCAPE up to 6,000 J/kg in its presumptive inflow region, this didn’t resemble the thermonuclear detonation, as have other storm initiations on giant-CAPE days in the same area like 26 May 1997. Instead, when we got closer to the storm between Henryetta and Okemah, it sported pulses of small updrafts.
As we positioned along US-69, the W edge of the Bigfoot jungle beyond which chasing in OK is just not worthwhile, another storm erupted to the immediate SW of the original cell, to our W, and also near Henryetta. To our N, through haze and intermittent low clouds, we also could see the top 1/2 of the tornado-warned supercell SE of TUL, itself headed into horrendously rugged terrain N and NE of Fort Gibson Reservoir. We let the base of this new storm get closer; but it remained rather flat and featureless, with only shallow, transient and innocuous lowerings.
The atmosphere from the new Henryetta storm southwestward past Ada then erupted almost all at once, using up a raft of that giant CAPE air in massively multicellular form. We gave up on the chase day, shot a gap through the big mess, and headed home.
Only after arriving back did we learn that a few hours NE of our junky storms, in Joplin, a rain-wrapped EF5 tornado engulfed much of Joplin, causing the worst tornadic death toll in the modern weather-warning era. Clearly the environment was a good deal different from there to where we had been–much of it on the storm scale. Horrible fortune played a part too; the same tornado several miles N or S would have missed town, likely causing few if any casualties. In a year of rotten placement of several cities with respect to the tornadoes that would strike them, this was the worst in terms of human toll.
Fun with Small Nebraska Panhandle Supercells
Harrison-Gering NE, 19 Jun 10
SHORT: Intercepted 3 nontornadic supercells in Nebraska Panhandle, one after dark near BFF.
LONG: A cold front had swept out of the Dakotas following our last storm intercept day. That stabilized the air mass for awhile and gave a couple of non-chase days for laundry, sightseeing, relaxed travel SW toward an eventual central High Plains target area, and photographing abandoned buildings of various kinds over the Dakotas and western Nebraska: an old schoolhouse, a long-disused, small-town rail station,a barn, the back door of another barn, a mostly intact farmhouse, and a gradually collapsing old house looking in and from without. Elke and I hadn’t been back in the Dakotas for a few years; and while storms beckoned us away, it was great to see the northern Plains again, especially in such a verdant, moist state.
The front’s trailing remnants stalled across the central High Plains beneath favorable mid-upper flow for supercells, while easterly and southeasterly flow to its N would yield decent low-level hodographs. A textbook, multi-day, central Great Plains upslope pattern was setting up, and we had time to participate before the chase season closed out. The main concern on this day was a lack of more robust moisture, but I wasn’t concerned much about whether we would see a storm form, given favorable upslope flow into the higher terrain of eastern Wyoming. We left PIR by mid-morning, targeting the Wyoming/Nebraska border region, with a short venture into the whimsical (but fun) tourist trap of Wall Drug.
As we left Wall Drug, convective towers bubbled over the Black Hills, but struggled amidst the lack of moisture. Moist advection started to solve that problem by the time we got down to around Harrison NE, with a discrete storm erupting to our SW over eastern WY and a short line of some overshooting cells to our NW (closeness exaggerated in the zoom view) across northeast WY, W of the Black Hills. Although both eventually would yield supercells, we went for the cleaner, more moist target to the SW.
We found a one-lane dirt road between Agate Fossil Beds and Mitchell, off NE-29 — no crowds, no traffic, nothing but us, a vast rolling prairie, a storm organizing into a slowly moving LP supercell, and dozens of different bird species joyously singing across the mild breezes.
The chase season to date, and the vacation in particular, had featured lots of driving and moderately- to fast-moving storms. This was a most welcome relief! We stayed there for nearly an hour, just enjoying the peace and solitude, punctuated only with an occasional rumble of thunder from the small, high-based supercell. It didn’t matter at all that this storm likely could never produce a tornado. The soothing salve of the Great Plains in springtime worked its rejuvenating magic on us, and we experienced the most pure, relaxing enjoyment in the face of a storm all season so far. It was a deep-tissue massage for the soul, a reconnection with why we’re out there to begin with.
I also, finally, had a chance to set up our new HD video camera on a tripod, and let it stand there and roll (our first video shooting in several years). [I eventually will construct some time lapses from this footage.] We had received this as a gift shortly before leaving on our trip, and I hadn’t really had a chance to learn how to use it right, amidst all the more active chasing we had done so far. The main intent of this video camera will be to shoot HD time lapses for our own enjoyment and perhaps uploading online; but first priority will be still photography. In this case, our video will feature a chorus of birds in stereo, the breeze, and an approaching storm.
As the first supercell grew more feeble, another small storm erupted very nearby to its S (and our SW), upon which I re-aimed the video and still cameras. This wide-angle shot shows both cumulonimbi at once, and illustrates how neighborly they were. It’s as if one was asking the other, “Would you like to come in and sit a spell? I’ve made some fresh lllllll-lemonade!” (quote [tm] Ryan Jewell). Instead, the northern storm shriveled to vaporous oblivion, leaving the southern one to spin along for a little while NW-N of Mitchell (and by the time of this shot, SSW of us). We finally decided to head S before the storm crossed NE-29, reserving a motel in the BFF suburb of Gering (which wasn’t easy due to all the hail-claim adjusters in town), packing the tripods, and beating the thin hail core across the road. This second supercell soon raised its base and weakened (view looking NE from a few miles E of Mitchell). It was time for some supper in nearby BFF.
As we dined, convection began popping up all around, almost at random, as if a pleasurable rash. Most of it was weak and inconsequential. One storm, however, took good root and became dominant to our WSW. We had some trouble finding the place of lodging we had reserved in Gering (in a neighborhood just W of downtown, but also just a few blocks from the entrance to Scotts Bluff National Monument, as it turned out to our good fortune). After we checked in, we headed over the hill S of the bluff to watch the now-weakening storm move in from the W. Its lightning slowed down dramatically as we set up tripods (of course), but not before one spectacular spark sliced through the twilight sky beneath for sloping base of the forward-flank anvil area. We also enjoyed seeing the apparently dying supercell’s remains float overhead beneath the moonlight, then headed back to our room.
While we were inside, unpacking and unwinding, I noticed lightning activity picking up outside. Another storm? No…after we gave up on it, the supercell rejuvenated and drifted just to our N over BFF, sparking anew from within! Out the door and right back up the hill we went, this time on its E side, to watch the spectacle. Once again, as we got set up, it weakened, but not before producing some nice intracloud flashes around a moonlit main updraft tower that was drying up from below.
I didn’t think to bring the new camcorder back out, and hadn’t yet tried the video functions of the 5DM2 still camera. So, instead, here’s a poor-man’s time lapse I constructed of still photos of the weakening storm moving away from BFF, where it had dumped hail up to baseball size. More work for those hotel-hogging insurance adjusters!