Bleeding the Turnip: Optimized Success in a Marginal Setup

July 15, 2012 by · Comments Off on Bleeding the Turnip: Optimized Success in a Marginal Setup
Filed under: Summary 

Okeene to Richland OK, Tuttle to Newcastle OK
29 May 12

SHORT: Intercepted entire life cycle of eventual Kingfisher-Piedmont supercell and its tornado, as well as twilight phase of separate supercell near Tuttle.


Nowcasting through initiation

After forecasting the potential for supercell initiation in a meso-beta scale confluence zone, somewhere between the west-central part of the KS/OK border and southwestern OK, Rich Thompson and I set out for the middle-ground target of the Watonga area for what would be our last Two Chumps chase of 2012.

The low-level moisture field over central/southern OK, in the prospective upstream fetch, had been eroded and fragmented by prior convection, so LCLs and cloud bases promised to be somewhat high for much of the day. Low-level flow wasn’t the strongest, either, but deep shear still fell within the margins of supercell and tornado days. Low-level forcing was subtle, but hourly surface streamline analyses revealed that confluence zone and its persistence. It wasn’t a classically straightforward setup at all. In fact, I had sent the following in a private note to a group of friends and associates before heading out: “Messy day–one of those that’s good for a needle-in-haystack ‘misoscale accident’…”. That’s exactly what happened.

The Two Chumps headed NW toward Watonga, encouraged not only by increasing juxtaposition of favorable parameters and foci in that area’s data fields, but also, good ol’ preconvective spotting with the human eyes that showed thicker convective towers in that part of the confluence zone.

In Watonga, numerous storm enthusiasts had accumulated to shoot the bull, empty the bladders and pass the time, with at least one (Conrad Ziegler) on a serious scientific mission. Conrad graciously invited us to a NSSL mobile lab vehicle to see data streaming in real-time from a freshly launched portable sounding. As we were discussing the weakening cap and other interpretive characteristics of the still-plotting RAOB, another use of the eyeball tool proved fruitful. Through the trees behind the Love’s fuel station, we caught a fair view of a very deep tower blowing the lid away to our NNW, near Fairview. Initiation!

Organizing to mature supercell stages

Rich and I cruised NNE to a suitable observation spot just S of Okeene, watching the towers deepen further, glaciate, and evolve into a bonafide cumulonimbus with some great anvil-aided crepusculars. As the storm started to anchor, grow and assume some visual supercell characteristics, we went E of Okeene, in its SE-moving path for a few minutes. We then embarked on a zigzagging trek with a net SE bearing, along well-maintained back roads, in and out of the sunlight, between Okeene, Loyal and Kingfisher. It was a tricky and difficult balance between getting in the storm’s shadow (better viewing contrast) and staying out of the intensifying forward-flank hail dump. In fact, at one point N of Loyal, we were getting subsevere hail in the sunshine!

While observing the twisting soda can of a storm, we were joined for a spell by BC, Ed C, Blufie and Joel Genung. Seldom has there ever assembled a more motley crew of grizzled, longtime, smart-ass chasers on an old dirt road. It reminded me of some friendly June convergences on the High Plains of Colorado, right down to the tan-colored wheat fields and high, roughly textured cloud base; but of course, the red dirt gives away the more southeasterly geography. We even could see the stacked-plate structure and shallow wall cloud of another supercell to the N, through the translucent core of the nearest storm.

Despite the insults and wisecracks dutifully exchanged, it was a pleasure to share several minutes of this young supercell’s lifespan with those guys…until the storm closed in and we had to disperse farther SE. We stopped a couple times between the Loyal area and Kingfisher as the storm expanded its base, produced more precip, and began to tighten up areas of enhanced cyclonic shear with occasional scuddy, slowly rotating lowerings.

Even though the ambient cloud base remained high, each lowering in a long series of them seemed to be a little better organized, condensing a little closer to the ground, thanks to some combination of lower pressure and higher RH, and a little more confidently rotating. This one, seen from S of Oneida, appeared as if it could tighten up to tornadic scale before being undercut by outflow. Nonetheless, that was one of my favorite views from the chase–again very Colorado-like under one of my favorite lighting conditions: looking NE into a high-based storm with little rear-flank precip, well-lit ground and darker forward-flank core area in the rear. That view seems to bring out some of the best texture and scuddy contrast in such storms.

Proceeding briskly southward on a dirt back-road, we were trying to reposition SW then S of the storm when a gustnado formed to our ESE, near the leading edge of the outflow from the nearer mesocyclone’s occlusion process. The resulting tube rose along the inflow-outflow interface and may have gotten involved with the updraft at cloud base (photo looking E, and contrast-enhanced version). If so (and that’s not certain), one could count it, though it was at best a fleeting and ephemeral “cheezenado”. I suppose we could claim it as tornadic if we were keeping score in some competitive tornado-fishing tournament. Fortunately storm observing isn’t like that, nor should it be.

We managed to get S of the storm for a short time as we found a viewing area on the SW edge of Kingfisher, watching an old occlusion to the N (manifest as a broad, outflow-undercut cyclonic shear zone) and a new one to the NE that rotated broadly but was still high-based. Under the latter, a scuddy, conical, slowly turning lowering briefly appeared above some dust–it would have been over the W side of town–but the dust appeared to be translating and not spinning. That’s good for Kingfisher.

Aware of the accumulating hordes of chasers and pseudo-chasers, we stayed off the main roads as much as possible in a SE-bearing zigzag between Kingfisher and Piedmont, remaining mostly S of the storm until reaching OK-3 (NW Highway) W of Piedmont. Meanwhile, reports of huge hail were starting to roll in–not surprising given the long-lived nature of this supercell and the environment it occupied. We had plenty of incentive to stay out of the hail core!

We stopped briefly on a dirt intersection near the Kingfisher/Canadian County line to watch a few short-lived areas of small-scale rotation in the newer mesocyclone, which itself had evolved into an elongated, cyclonic shear zone at cloud base with an ill-defined clear slot and some turquoise-toned precipitation areas. The episodic zones of cloud-base rotation were tighter and stronger than at any prior time in the storm’s lifespan, but still brief, shallow and apparently undercut. The storm acted like it wanted to produce a tornado, but needed some outside assistance.

Tornadic stage

It was during that maneuvering that we began to realize that a left-mover to our SSE was going to crash into the forward flank of our supercell, given their respective, extrapolated motion vectors. More importantly, the outer part of the left-mover’s rear-flank gust front (RFGF), which on radar reflectivity imagery arched NW and W out of its parent storm, eventually would smack into the mesocyclone region of the cyclonic supercell, somewhere not far SSE of us near Piedmont. We surmised that could be the outside assistance, and our best opportunity to see a legitimate spinup.

After all, think about the sign of the vorticity produced by the same relative part of a “normal” supercell’s RFGF: anticyclonic. It follows, therefore, that the same segment of the anticyclonic left-mover’s RFGF will contain enhanced cyclonic vorticity. Infuse any right-mover’s mesocyclone with more cyclonic vorticity along a boundary, and things could get very interesting for at least a few minutes, until the air behind the boundary gets too stable for the right-mover’s updraft to process efficiently.

Yes, we were nowcasting these processes, and charted a course down OK-3 to get just SE of the most likely interaction spot and witness it front-row, ringside. We also reprised an old quote of Rich’s from 1998: “Something out of this is gonna do whatever’s going to happen.” Even after conceptualizing how it could occur, we were amazed that it actually did!

In this shot, the mesocyclone area is seen to our NNW (the road goes NW). The center of the mesocyclone was translating generally SSE toward a spot just to our W. It didn’t look like anything imminently threatening–still with a rather high, ragged cloud base, and a much bigger dump of precip to its N and W than ever. The RFGF from the left-mover was passing our location with a wind shift, behind which we noticed only slight apparent cooling. We maintained position as the mesocyclone approached and the left-mover’s RFGF proceeded into it, saw a radar truck and some other chasers (including media trucks) bail SE past our watch at high speeds, and then…

Within the broader meso, a compact area of cloud-base rotation appeared with a small, tight fan of spinning dust beneath. Tornado! Here’s a wide-angle (full-factor 30 mm focal) within 10-15 seconds after tornadogenesis. Ground circulation was less than a mile to our NNW, time 2018 CDT (118Z), and we were located 3 N of Richland. It had no condensation funnel yet, and wouldn’t for several more minutes as the circulation churned S toward and across OK-3.

This wide-angle photograph shows the circulation with about its greatest dust production, before it rapidly wrapped in rain, crossed OK-3 with a power flash, and spun across wetter ground. The dust, scud above and cloud base were rotating in sync, as was the case when the cloud-base feature began to narrow after crossing the highway. I stood out in the wrapping rain as the weak tornado moved W through SSW of us, shooting wide-angles of the tornadic circulation at cloud base with what little dust it could raise, until 2024 CDT (124Z). At its closest point, the tornado was around half a mile away, with a few embedded subvortices–but never expansive enough to threaten us directly.

Of greater concern was the hail wrapping all the way around the meso–some of which started bouncing off the road around us and looking bigger than two inches. A few minutes before tornadogenesis, the supercell had dropped at least five-inch diameter hail N of Piedmont! Fortunately, none of the damaging hail hit the vehicle as we bailed SE on OK-3 then S on OK-4. We still were in transit (S on OK-4) during the short-lived, rain-wrapped condensation funnel, which Rich could see to our W from the passenger seat at about 2030 CDT (130Z). We actually didn’t get any photos during the condensation stage due to being mobile. By the time we found a safe pull-off, the tornado was gone.

Tuttle-Newcastle evening supercell

Storm mergers and outflow soon doomed the old mesocyclone area, and a major convective mess took over. In darkening twilight, we continued S on OK-4 past I-40, noticing a storm with a fairly large updraft area to our distant WSW and W. That storm assumed some supercellular characteristics, both visually and on radar, but we admittedly were surprised by unconfirmed media reports of a tornado in the Union City area.

We found a side road W of OK-4, a couple miles N of I-44, and began observing the supercell as it moved over Tuttle. Illuminated in various ways by lightning, town light and twilight, this storm was a beauty! I shot numerous photos as the storm approached, mid-upper level electricity brilliantly illuminating the scene aloft as its striated skirt swirled ever closer.

Hail markers on this storm seemed rather large, so we went to Newcastle (in its path) to find an overhang and observe the hail. By the time the storm reached there, however, it had grown upscale into a mess and merged with other cores, producing mostly heavy rain and small hailstones. Tired from a long chase day (and evening!), the Two Chumps then aborted intercept actions and turned E to Norman, satisfied that we milked this atmospheric regime for all it could offer–except the five-inch ice bombs, of course, which we chose to avoid.

Central Oklahoma Tornado Outbreak

June 4, 2011 by · 1 Comment
Filed under: Summary 

El Reno/Piedmont, OK EF5 with Satellite Tornado
Dale, OK EF1 Tornado
24 May 11

SHORT: Intercepted tornadic supercells NW and E of OKC, the first with a violent tornado in progress, the second offering a scenic rope-out.

Welcome to a “High Risk” outlook and “Particularly Dangerous Situation” watch scenario that verified, weather-wise, exactly as such for central Oklahoma: in summary, three different violent (EF4+) tornadoes arose beneath three different supercells, with a fourth big tornado rated EF3 in northwestern Oklahoma (NWS Summary). Through both skill and luck, we witnessed what has been rated as the biggest and baddest tornado of the lot; yet we are respectfully mindful of the human toll that it took in spite of absolutely outstanding forecasts and warnings.

This almost classical Southern Plains tornado outbreak was so well-forecast and so thoroughly handled by SPC, local offices, local media and EMs, that I’ll eschew discussing meteorological details, offer a few prototypical 21Z (4 p.m.) mesoanalysis graphics that pretty much speak for themselves…

    MLCAPE and CINH | Effective Bulk Shear Magnitude | Effective Storm-relative Helicity | Observed ~850-500 mb Crossover | Effective SCP | Effective Sig. Tor. Parameter

…and now go straight to “the chase”. And what a “chase” it was, right into the area of maximized parameters you see on those linked mesoanalysis graphics, and at about that time.

Phase 1: Intercepting the Piedmont Supercell

After looking at some data at home, and at Ryan Jewell’s house, Jack Beven and I targeted the area near and just N of I-40 in west-central OK, mindful of the likely fast storm motions of the day and the need not to get too close, to soon, to developing storms. As we headed W on the big slab, the earliest cell of consequence erupted SW of Fairview, not too far from the previous day’s tornadic intercept. Indeed, though we didn’t target the storm due to incompatible relative motion vectors of it and us, it would produce a couple of tornadoes over and near Canton Lake.

Storms were forming closer to each other than I like, causing some interference and precip-ingestion problems. We waited just E of Watonga for the next supercell in a broken band of them, hoping to get a quick look while ultimately targeting the southern storm in the same grouping–the storm that would become the El Reno/Piedmont supercell. A quick jog back W to the fringes of Watonga, as the storm passed, revealed an outflow-dominant heap; so we flipped the vehicle back eastward, heading for Kingfisher and the next decision point.

As we got to Kingfisher, the big deliberation was: wait for the storm E of town on a good E-W road and risk that it would right-move to the morass of stoplights and traffic of Guthrie, or head S on US-81 to Okarche and risk munching some of the forward-flank hail along the way?

The radio station was blaring frantic TV simulcast reports of a “wedge” headed for El Reno. We vacillated for a couple of minutes, and I had my doubts; but Navigator Jack’s front-of-the-map calculations convinced me we could pull it off. We headed S toward Okarche into dreadfully darkening murk, intensifying rain, and ultimately, some hail, while hearing of the same “wedge” crossing I-40. Often such tornado descriptions are exaggerated; but I knew that, on this day, violent, large, and long-track tornadoes certainly could happen. Unknown to us, at the time, the tornado was sideswiping the El Reno Oklahoma Mesonet site with an 18-mb pressure drop and measured gusts to 151 mph–the strongest winds yet clocked by that network of weather stations.

Rounding the SE turn onto OK-3, we vectored an intercept position for any tornado coming NE out of El Reno. Blistering barrages of close CGs hammered the ground all around us, a fusillade so furious that I pulled my radar-delivering I-Phone out of the car jack, and we refrained from touching anything metal. A few hailstones clunked off the roof–none ultimately large enough to do damage, though we did see stones around two inches in diameter bounding off the road. The really huge and destructive hail was no more than a couple of miles to our S and SW; we had left Kingfisher in the nick of time to get around it!

We pulled S off OK-3 at Cimarron Road, about 5 WSW Piedmont, and drove S about a mile to a fine hilltop vantage. CG activity was backing off a lot, and we were (for now) out of precip. I could commence photography in relative safety. It was so stinking dark under that storm that I had to crank the ISO up to 1600 just to hand-hold shots with 1/25-1/60 sec shutter speed at f2-f4! At a time like this, I was so thankful for having invested in a top-end Canon DSLR and the L-series glass on the front. Using lesser equipment and especially with my old slide camera (which usually contained 100 ASA film), successful collection of the following shots would have been impossible.

And so we waited, looking along a lengthy cloud base from W-SW, footed by some dark murk well to our SW. We knew where the tornado was from the constant TV reports–buried in that murk–but couldn’t quite see it yet with our eyeballs. In fact, it was only after I took this 34-mm shot at 1630 CDT, then looked at the viewfinder presentation of it, that I finally could ascertain the outline of the tornado embedded in that murk to our SW (severely enhanced crop of same photo)! It was moving NE (toward us) at 40-50 mph. We had several minutes to hold position before having to decide whether to jog S on our paved, N-S road to get out of its way.

At first a multivortex containing a fat, tilted stovepipe, the tornado took on a wider configuration with a fat barrel and adjoining cone being two of the more persistent, larger tornadic vortices involved. Even at that distance, we began to make out wild cloud motions and rapid revolution of vortices around each other. The barrel temporarily vanished at 1632 CDT to reveal a fat stovepipe within an obviously significant, broader tornadic circulation.

Despite all the precip evident to the left (SW through SE) of the tornado cyclone, it maintained enough of a weak-echo moat around its immediate vicinity that our view kept getting better and better. The tornado also was growing larger as it got closer, closing in fast, not moving much right or left. This meant we likely would have to bail S sometime soon. But first, more observation and photography ensued as the tornado’s form fattened into a wide, dust-flinging barrel, then a bonafide wedge. The ambient wall cloud and occlusion-downdraft slot also became more apparent, contrast and visibility continually improving for the time being. We were impressed…very impressed. I told Jack, “Congratulations…your first violent wedge tornado.” Jack has been taking chase vacations to the Great Plains since the mid-1990s, often with the most deplorable luck in weather patterns. This was a new and potent experience for him.

As this grinding behemoth drew closer, I was supremely confident in its violence, while dearly hoping nobody was sheltering above ground inside its path. [I didn’t know it at the time, but this monster had killed several folks already around I-40.] The motions in and around the tornado were of a ferocity I’ve seen, in person or on video, only with tornadoes ultimately rated F4 or F5. As the sides of the condensation wedge appeared to froth and oscillate wildly, chunks of scud materialized at ground level in incomprehensible fractions of a second and raced diagonally up the and around the vortex at breakneck speed.

Given its slight rightward translation, I was reasonably confident the tornado would miss our location–but not my much. Any rightward turn, however, and we would be in grave peril with precious little time to spare. At 1635 CDT we turned S and drove a mile. As we pulled back onto Cimarron Road, a well-defined, horizontal accessory vortex formed on the near (NE) side just above ground, coiled around the N side, and rolled vertically up the rim of the tornado. This was a new experience for me, having seen the phenomenon only on videos of violent events such as Red Rock OK (26 April 1991), Golden Gate IL (2 Jun 1990) and Tuscaloosa AL (27 Apr 2011). Had I stayed at the previous location 30 more seconds, I could have photographed that too.

As good luck would have it, the tornado took a temporary NNE jog as we rolled S, maintaining safe distance. As bad luck would have it, torrential rainfall began wrapping around the SE and E sides of the mesocyclone, thoroughly dousing me in a veritable firehose of water after I jumped out and ran into photographic position. Barely able to stand in the roaring inflow, I hoped for just a shot or two before the camera would get too wet. It grew into a very wide, menacing wedge all the while, its collar cloud blasting around the mesocyclone with amazing speed. As the tornado moved to our WNW and NW, I clearly heard its roar–a throaty, primeval rumble somewhere in pitch between the closed-mouthed growl of an angry bear and the muffled booming of continual heavy-artillery fire.

This was one bad, bad, bad mother.

I reeled off one final good shot at 1638 CDT–capturing a satellite tornado that had just emerged from behind (W of) the big one, and was orbiting around its near-SSE side, throwing up a dust plume of its own. The satellite then turned NNE in front of the main event’s E side, and became lost in worsening contrast. The last and only other satellite tornado I saw was on 3 May 1999, near Chickasha.

Within seconds, the big tornado right-turned ENE again and got so wrapped in rain that we barely could see it anymore. It crossed OK-3 just W of Cimarron Road, and as we cautiously crept N back toward OK-3, crossed Cimarron road less than a mile to our N. Needless to say, I was glad it was moving away from us, while glancing overhead and around often for more satellite vortices. Furiously wrapping rain curtains parted just enough to reveal the E edge of the condensation vortex to our near-NNE, rightward of some power flashes. This was my last clean view of any part of the tornado, at 1640 CDT.

Meanwhile, the combination of inner-edge RFD plus southern-rim inflow to the tornado was severe at our location. The forward housing for my outside rear-view mirror launched itself like a rocket off my vehicle and sailed airborne for hundreds of feet out into a field to our NE, as the vehicle shook in the gusts. We were safe (barely), but also, not inclined to go any further N for a minute or two.

Even though the tornado did miss our initial photographic location, it wasn’t by much. I’m still glad we moved…under half a mile from the edge would have been unsafely close for a certifiably violent, still-expanding, precip-wrapping monster with proved tendency for satellite tornadoes and accessory vortices writhing around its rim.

Then hit a horrifying realization-–this tornado was headed generally toward the residence of my friend (and fellow storm observer) Rocky Rascovich, N of Piedmont. I tried to call and nobody answered; fortunately, it turned out they already were in shelter. His wife assured me later that it (barely) missed them and they were OK. It was the sort of tornado–fast-moving, expanding, wrapping in rain–that is the most dangerous and hardest to observe safely.

Later news of the deaths near El Reno and Piedmont humbly counteracted any sense of gratification I had that evening at getting the good-contrast, big-wedge shots about which I had dreamed since childhood. This is the ethical paradox and dichotomy of conscience for any storm photographer.

Phase 2: Intercepting the Dale Supercell

Cruising along the mostly empty Kilpatrick Turnpike (around N OKC) we briefly debated whether to go up I-35 and meet the storm at Guthrie; but its deep precip-wrapping and messy radar appearance convinced us to jump SE for newer storms headed out of the Chickasha area. Early reports of tornadoes from those sealed the deal.

Jack and I tried to get S of Norman, but were stopped by a traffic jam on I-35 in town (flipped car unrelated to tornadoes) and couldn’t get to Goldsby readily to observe that event. Had the Goldsby tornado turned slightly more leftward and gone up I-35, it could have plowed through hundreds of stopped vehicles up and down the highway!

Instead we waited a short time near the North Base for what was left of the Newcastle storm (by then, nearly nothing), then backtracked some back roads to I-240/40. Along the way I spoke to Elke; they headed to my neighbor’s underground shelter as the Goldsby event headed for Norman. In northern Norman and along I-240/40, Jack and I encountered occasional marginal-severe hail and falling small debris (insulation, leaves, small twigs) that had been launched by the Goldsby tornado into the supercell’s far-forward flank.

The Goldsby storm also had been slammed by a left-mover, temporarily disrupting its organization, dousing the once-violent tornado before it could grind through some part of Norman. I was glad of this, as it spared a lot of destruction in the town in which I reside!

As the supercell reorganized, we vectored the new mesocyclone to cross W of Shawnee near Dale, in a mostly hilly and forested area. Fortunately I knew of a large, flat, open field just S of the I-40/OK-102 (Dale) exit, from which I had photographed the OKC ice-machine storm of 16 May 2010. We headed there and waited for the reorganizing mesocyclone region from the approaching supercell to come into view.

From the murk, at 1830 CDT, a low-hanging, conical cloud form appeared to our W, hard to see at first beyond the red farmhouse in the last shot (super-enhanced crop). This feature had good temporal continuity with what would emerge more visibly by 1832 (super-enhanced crop)–the Stella-Dale tornado, as a tilted cone beneath a deeply clear-slotted wall cloud. We weren’t totally sure yet by our eyes, even then (given the hazy conditions); but by 1833, it was obvious that a tapered cone tornado with debris fan (super-enhanced) was moving in a general ENE direction to our WNW, very close to I-40.

As the tornado grew closer, its form gradually became sharper and also more sinuous, contorting spectacularly into a long curved tube. I was so mesmerized by the wondrously serpentine evolution of the visible vortex that I didn’t think to slap on the zoom lens until the tornado roped out at 1836 CDT. What was left of the mesocyclone next moved N of us, got undercut by rain and outflow, and vanished into the murk N of I-40.

We cruised E on I-40 to look at two more supercells near Prague and Okemah; but their structure was more amorphous, with little evidence of robust low-level rotation by that time. Along the way back, we noticed mostly minor (Ef0-1) damage alongside I-40 2.5 W of the Dale exit, where the tornado crossed. The wreckage of the big rig, whose trailer got blown to pieces, still was being hitched up to a towing vehicle.

By the time we got back to Norman, we were thankful that my home (and those of others in Norman) was spared, and that we got a high-contrast view of a violent wedge…but also, once again saddened for the casualty toll from yet another deadly tornado day among far too many this year. We met up with the Fogel crew for dinner (they had far worse luck than we with tornado observing on this day), as well as Elke and my kids, swapping stories of a great chase (us), a frustrating one (DF’s crew), and another Norman scare (my family). Aside from a dollop of mental exhaustion, my other impression was: “I’m about ready for the High Plains!”