Bennington Tornado
Bennington KS
28 May 13
High Plains Therapy, Day 5 of 5
SHORT: Absolutely amazing chase day, top-5 all-time quality. After a very leisurely and relaxing morning on cool side of boundary, and long lunch, intercepted stationary supercell with two tornadoes near Bennington KS. Observed violent and often large tornado from one spot for over 1/2 hour as it underwent multiple shape changes and precip wrappings/unwrappings to our W.
LONG:
Background
Fans of “The Matrix” will get this. Pretend you are Morpheus and I must select from five pills instead of two. You ask me, “What if I told you that you would be presented with five violent-tornado days in Kansas and Oklahoma this season? On one of these days you will be at work. On three others you will chase but see no tornadoes. Only on the remaining single day will you see the event…but you get to choose which. ”
YELLOW PILL: Photogenic sunset tornado in western Kansas and one or two others from same storm, with other messy storms nearby.
PURPLE PILL: Two raging, roaring beasts in the central Oklahoma Crosstimbers with occasional, briefly unobstructed but amazing views; sucker storms in Kansas.
BLUE PILL: One photogenic tornado, but it’s yet another deadly, horrible monster in Moore. A ghastly and unwelcome event, for sure.
GREEN PILL: Mostly very visible, sometimes rain-wrapped brute, nearly stationary for 45 minutes, at times audible; if you want, you could put out camp chairs and coolers, and have a five-course tailgate picnic while observing safely.
RED PILL: Huge, diffuse, erratically moving/expanding and highly dangerous mess that kills respected friends, nearly takes several others, and makes everyone you know profoundly saddened.
Immediately, the red pill is tossed, followed by blue. After careful consideration…
This was the day of the green pill.
Words cannot express how glad I am, several months later, to be able to say that–as frustrating as the yellow, purple and blue days (18-20 May) were at the time. The red day, I was at work and damned glad of it; I am quite satisfied to have been on the evening shift instead of tangling with El Reno’s tornadic phase.
Decisions and leisure
Before going to sleep the night before, in Smith Center, KS, I knew I had just one chase day left before having to return home for an evening shift on the 29th. Already seeing supercell potential for the 28th in two main areas–upslope flow with large hodographs but high cloud bases (eastern CO) and big hodographs, with low LCLs and high moisture along a boundary (in central to northeastern KS)–the choice from Smith Center was pretty easy. As much of a “structure guy” as I can be sometimes, this day I’d have to go for the conditional but potentially juicy tornado threat that was mostly on the way back to Norman. “If it stays capped, at least it’s just a few short hours home.”
Perusal of morning data and short-term progs confirmed that a front was stalling ENE-WSW across KS, obliquely intersecting a dryline that would mix E to somewhere not far W of SLN by mid-afternoon. Low-level winds and mass convergence weren’t particularly strong, but would improve through the afternoon as absolute and differential heating (lots of low clouds N of the front) augmented boundary-based left. The target was obvious–the SLN area or a tad north–only a couple of hours away, with at least 6-7 hours to get there. I liked that news.
Being north of the front, in cool air shaded by low stratus, I wasn’t in any hurry to bake under the high, midday, warm-sector sun of late May. Instead I pulled off a couple of times between Smith Center and Luray simply to open the windows, recline way back, and sit in quiet solitude: just me, the cool breeze, the green, undulating prairie, and songs of birds. So relaxing was one such stop that I actually dozed a little. There’s nothing like a stereophonic meadowlark lullaby to soothe the soul and cleanse the mind.
By the time I hit Luray, the stratus had become stratocu and was breaking into scuddy rags. As I fueled there, Tony Laubach (who was headed from SLN to Colorado) posted a message informing me of a horrendously long traffic backup along eastbound I-70 south of me, and W of SLN, and advised alternate routes. Grateful for the advice, I went down K-18 toward Lincoln, generally aiming for the Bennington area near US-81.
Still with plenty of time to kill, I had a long lunch in Lincoln, nibbling away on an Italian sandwich and salad buffet at Pizza Hut while checking obs, and also, checking in with the progress of my chase caravan partners. By this time, I was glad to be indoors; the boundary was nearly overhead, and temps were getting warm as the sun beat down outside. Objective analyses showed that deep shear was increasing, the front was quite vorticity-rich, mixed-layer CAPE was soaring past 2,500 J/kg, and the boundary only would get more unstable in the next couple of hours as it cooked. The dryline intersection was due south; so I eased on over to the US-81 rest stop near Bennington to stay downshear from that.
During my stay at the rest stop, the Dudes, Dudette and Dogs crew finally finished with their windshield replacement in SLN. That took so long that chasing in Colorado was absolutely out of the question–and what do you know, about the time they were ready, and while I was throwing rocks at the rest area and scanning the skies, big towers were going up all around SLN. Isn’t that convenient?
Chase on
The deepest early towers formed almost overhead and started moving ENE along the boundary. I headed through Bennington toward Junction City to stay ahead of them, just in case they evolved into a storm, with an eye back toward that intersection near SLN. Way off in the distant NE, a huge pile of convection was visible through sporadic low clouds. On radar, that sucker was evolving explosively in just a few scans, from a cluster of echoes to a gnarly supercell with classic hook and tremendous, tornado-warned velocity couplet.
Only briefly was I tempted to go that way, however; the storm was over 90 miles away along an indirect route. Seeing Eddie Aldrine’s report of a large, slow-moving tornado near Corning (NNW of TOP) actually encouraged me for potential nearby. Surface vorticity and low-level helicity were comparable…and CAPE was bigger. If that storm could produce a fat, long-lived hose, surely anything that went up between me and SLN could be special. I stayed put near Talmage to monitor nearby towers and a few weak echoes newly developed just NW of SLN.
Meanwhile, the people and animals of the companion crew were on their way toward a meeting spot between Talmage and Bennington when the echoes NW of SLN went absolutely berserk! In what seemed like no time, the western sky grew dark with heavy anvil shading and a big supercell started to take shape W of Bennington. We joined forces and wandered N a little, thinking (erroneously) that the Bennington storm with the distant but big updraft base would move NE.
After a brief chat with the original Twister Sisters and another examination of convective trends, it became apparent that this storm was stuck in place, anchored immovably and telling us, “I’m not going anywhere. You have to come to me!”
Little tornado, big tornado
Back down to K-18 we dropped, then zoomed W toward Bennington. Rolling over some hills, we saw an odd protuberance just S of due W under that distant base…funnel! The condensation funnel briefly grew fully to ground contact…tornado! However, we didn’t dare stop to shoot, since this fleeting vortex likely was just a teaser. We knew what the Corning storm did with less, and didn’t want to be out of position for the big show from that big base.
So it was. We crawled through, then past, a nest of chasers parked and driving hither and yon, in and around Bennington. Easing a little closer, we found a relatively clean position with safe pull-off and southward escape option about 1.5 miles WNW of town along a paved, N-S road. Though a tree row was about 1/2 mile to the W, cloud-base rotation was increasing, and we dared not gamble on another vantage.
Just in time too…for enough low clouds dissipated around the storm to reveal nicely spiraling structure overhead, while a wall cloud began churning. We thought tornadogenesis was imminent every few seconds for another 5-10 minutes as the wall cloud (wide angle view) turned around and around and around at visual speeds I’ve only seen with tornadic events, with similarly rapid tail-cloud inflow. I tried to call this in to TOP, but got a busy signal.
Finally, a funnel formed on the left (S) side of the mesocyclone, quickly becoming an obvious cone tornado. A brief burst of CG lightning strikes a couple of miles to our E and NE sent me back into the vehicle, whereupon I got another busy signal on calling TOP. From here on, I called the updates into Hastings instead, for relaying to TOP.
A welcomed development: the lightning quickly calmed down, at which time I could have whipped out lawn chairs, sat back, kicked up my feet, cracked open a couple of cold ones, eaten a pizza or two, and enjoyed the view. For the next half hour, we stayed in that spot, watching the tornado grow in size, shape-shifting from fat stovepipe to barrel to wedge and everything between, a big doofus of a tornado lumbering slowly in a confined loop to our W, SW, W, and NW, getting close enough to hear but not to compel evacuation, nearly disappearing in precip then emerging again, more than once, until it ultimately got too rain-wrapped to see anymore. Then it kept going for awhile longer.
Being able to stay in one spot and watch a quasistationary, violent tornado go on (and on, and on…) in mostly uninhabited countryside…this was a completely unfamiliar and wondrous experience. Behind us, in Bennington, sirens wailed on and off for most of an hour, never needed but definitely justified–for the supercell could start moving anytime. Fortunately for the town, it didn’t, and fortunately for us, as we were between the tornado and those sirens.
Thanks to tornadic translation vectors resembling those of a two-year-old on a tricycle, I had time to call in several updates, take well north of 100 photos, post a live phone shot or two to Facebook, and just put the camera and phone down and stare with awe and appreciation at the atmospheric event unfolding just a couple of miles to the W. In fact, at one point, as the slow path loop got closest but turned northward, I closed my eyes for 30 seconds just to listen to the tornado’s deep, low voice and feel the inflow it was consuming, undistracted by anything visual. This, I promise you, was an ethereal, transcendental experience. How often will one get that opportunity?
Many moons ago, DF had vowed to release the cremated remains of his late canine chase companion, Thunder, into a tornadic supercell’s inflow. When I looked to the left and saw him shaking a bag into the strong, warm easterlies, and saw the ashes wafting westward across green fields toward that big tornado, I nearly shed a tear. Somewhere in doggie heaven, a big, goofy leonberger (who himself had seen more than a few tornadic supercells in his short life) was smiling and wagging his tail.
As for the tornado at hand, here’s a selection of images every few minutes through the rest of its visible lifespan:
Thick cone, wide angle with ambient storm structure
Barrel under big wall cloud, opaque rain-wrapping
Very fat hose, descending reflectivity core shed
Absolutely classic pose–big tornado, big wall cloud, big base
Another DRC, thick precip wrapping
Wedge, opaque curtains all around
Slight zoom view of wedge (could hear it at this point of closest approach)
Wedge with ragged, possibly multivortex filaments to its N, meso getting quite strongly occluded
Near-wedge again, thick rain-wrapping
Deeply rain-wrapped, barely visible thick, tubular cone with tail cloud nearby
Fattening again through precip gap
Last certain view of tornado before wrapping precip got too thick, once and for all.
Closing it out
We waited a few more minutes of waiting for a visual reappearance, while precip curtains orbited very fast about an inferred tornado location. It obviously was still going, and would be for at least a few more minutes. However, we also knew that no tornado survives that deeply occluded and buried in precip for very long; one only can suck in so much heavy precip before the inflow air mass becomes too dense and stable.
Seeing the rear-flank cloud edge (and core) extend nearly overhead, we decided to go back through town a couple of miles and take a big-picture perspective. This storm now resembled a large, HP drum, maybe with a dying tornado still buried in there somewhere. Seeing some rotation in a cloud base ahead of the core, we went back through town again, observing a brief, rotating wall cloud that soon got undercut by outflow.
Thinking this storm might finally move off the hodograph origin, we went W and S on K-18 across Salt Creek and briefly observed the big, turquoise-cored HP storm from a roadwork area (looking NNW and looking SSW). Other cells were forming atop its outflow, but upshear, merging in and messing up the structure.
After jumping a few more miles to the SSW, we sat in the dimming daylight for one last look at the steadily disorganizing supercell, still in the same area and surely dumping astounding storm-total rains, before heading the few miles S into SLN for celebratory dinner. Good times with friends, followed by an uneventful 4-hour drive home, capped off a decidedly successful five days of High Plains Therapy. The next day–back to work, rejuvenated and alive with the passion for the smorgasbord of atmospheric violence!