Smith Center Tornadic Supercell
Smith Center, Esbon & Mankato KS
27 May 13
High Plains Therapy, Day 4 of 5
SHORT: Wild day. Intercepted tail-end storm W of Smith Center KS that started CL and became messy HP, saw at least 3 tornadoes therewith. Fateful hail later encountered near Mankato.
LONG:
Prelude to action
Three days of this weather pattern had graced us with some outstanding storm structure and lightning in Colorado, Nebraska, South Dakota and Nebraska again. On this fourth day of the five I could chase, we started out in Grand Island for what promised to be a fairly short trek into extreme northern KS–me in one vehicle and a lot more protoplasm in the other: DF and Samara, “Downtown” Brown, Ross da Boss, and intrepid leonbergers Porthos and Trego. In my vehicle–music, calm sailing, and the hum of the road. In theirs–canine farts…from very, very large dogs.
Strengthening deep-layer wind profiles, the best low-level moisture content of the warm sector so far in the pattern, strong CAPE, a deepening surface low over western KS, and a quasistationary baroclinic boundary near the KS/NEb border, all made the target zone fairly obvious. The dryline was a possibility, but with capping a major concern, so it was downshear boundary or nothing for us. Wind fields certainly would be favorable for supercells. Lower LCLs than previous days amidst enlarging late-afternoon hodographs offered some glimmer of hope for a tornado if the storms first formed, and the modes didn’t get too messy too fast.
Unfortunately, with such a readily apparent target would come throngs of actual and wannabe-chasers, likely followed by looky-here locals, and we knew this. Finding safe navigation options off the main roads would be important to minimizing the hassles and hindrances to safe storm observing posed by traffic jams. Yes, traffic jams in rural KS! How sad is is that we have to consider this anymore? Still, I wasn’t about to let that ruin my enjoyment and appreciation of what nature had to offer, if I could help it at all.
After a long wait N of Stockton, we finally watched several towers arise to our NNW and NW, initially elevated N of the boundary but deepening into cumulonimbi and backbuilding. Meanwhile deep towers fired to our S and SE, in the warm sector E of the dryline. The latter didn’t benefit from as much forcing for low-level mass continuity as provided by the boundary, but had access to higher surface-based CAPE, at least at first. We wandered S and E, monitoring and remaining in play for both areas, when the northern storm cluster finally backbuilt close enough to the surface boundary for Tail-end Charlie to get really happy.
Tornadic stages
Overshoots and thick towers pumped through the persistent southern storm as we turned N out of Osborne toward Smith Center. We got a good view of the initially high base while approaching Smith Center, then set up just W of town with just a few minutes to observe the broad but increasingly well-organized updraft region before the flanking gust front would reach us.
An otherwise undistinguished area of the cloud base roughly in the middle of the last shot, between precip areas, started to rotate quite noticeably. Why? We didn’t notice any particularly telltale signals, such as an antecedent RFD cut or obvious occlusion process. Maybe this was the stretching term at work–a “nonmesocyclone” tornadogenesis process in a supercell, fortuitously located under an elongated updraft area and ravenously sucking a straw of horizontal vorticity. In any event, a weak tornado formed–a dust whirl under the little area of cloud spin, so feeble at first that it took us a couple of minutes of staring to be sure. There was a minute or two gap between obvious dust whirls, but with continuity of cloud-base rotation above, I considered it one tornado with a vortex too weak or too vegetated at the base to raise dust in that intervening stage. Off and on, but mostly on, the little tornado that could stayed visible, lasting for six minutes before being plowed under by the rear-flank gust front of a low-level mesocyclone deepening to our N.
With the supercell changing character and moving abeam of us, it was time to “head east”–and I don’t mean the ’70s rock band. The warning and tornado report attracted swarms of chasers and pseudo-chasers from several counties around, many of whom could be seen on Spotter Network animations about-facing to this storm as soon as the red polygon appeared. US-36, E of Smith Center, turned into a long, eastward-slogging train of vehicles paralleling the storm just to its S and SE. For a little while, we were caught up in that mess, and had trouble finding good vantages.
We needed one when an area of low-slung scud to our N and NNW, under a cyclonically turning inflection notch of the updraft-downdraft interface, started turning itself as it rose off the ground. The persistent, obviously but slowly rotating cloud column was in contact with both ground and cloud base for about a minute. The whole very weakly tornadic circulation (located just N and NE of Bellaire and NW of us ) lasted about 3 minutes.
Farther N, the storm cranked up a robust mesocyclone, but one hard to see from the S, through intervening precip. Finally, this storm was getting serious and bidding bye-bye to the “cheesenado” phase. Our vantage wasn’t ideal, and we wanted to get E and N to reposition ahead of the new, deepening storm-scale circulation. Several minutes of waiting for a hole in the US-36 traffic didn’t help. As a result, we did get N on the alternating paved/dirt road into and out of Esbon, but not in time to see most of the lifespan of the big, rain-wrapped tornado NW of town.
Instead, we popped N out of Esbon barely ahead of a deep, dark, circular drum of rotating precip, churning menacingly and moving ESE directly at us. With no vehicles driving toward our position (but several high-tailing it away!), and a narrow but very passable road upon which we had just driven as a return/escape outlet, we safely executed requisite 5-point turns to flip back southward and, as a Texan like me would say, “Git the hell outta thar!” After they finished the turn and as I was amidst that process, I heard Keith yell over the radio, “Tornado to the west!”
Sure enough, inside the orbiting moat of heavy rain, I could make out a low-contrast, wedge-shaped mass of darkness, itself rotating furiously. Seeing that the E rim of the meso still was W of us, though not by far, I radioed to the now rapidly fleeing Dudes, Dudette and Dogs vehicle: “Go ahead south! I’m gonna take 30 seconds to shoot then I’ll get the #%^! outta here!” As I parked and jumped out, the mass (which indeed was the infamous Lebanon-Esbon tornado) narrowed to a barrel shape, then by the time I did shoot, a thick cone, getting lower in contrast again (enhanced version of last shot) and still densely swaddled in precip.
Meanwhile a newer and rapidly strengthening mesocyclone was whirling with considerable vigor to the N, raising dust and sucking it in, wrapping big gobs of precip, who-knows-what going on inside. I could have sworn I saw some vortices merry-go-rounding in there, but contrast was too poor to say for sure. No tornadoes showed up in storm reports during that phase, but at a minimum, it was a very intense “meso on the ground”. The southern, older, tornadic and deeply occluded circulation still was moving generally toward me, the tube narrowing to the extent I could ascertain. [Storm surveys later showed the Lebanon-Esbon tornado dissipating right before it reached my road.] Still, not wishing to play chicken with a beast like this (the storm always decides who wins that game!), I jumped back in and gunned it southward also. Everything since the 5-point turn occurred in less than 45 seconds, 15 longer than estimated: stop, jump out, shoot WNW at occluded/tornadic meso, run across the street, shoot N at new meso, run back to vehicle, throw ‘er into gear, slam the pedal down and bust south.
Adventures anew
Apparently, my storm-intercept companions used a great deal of haste in their escape; for by the time I reached the next intersection, they were out of radio range. While I turned E to stay ahead of the rear-flank gust front of the new meso, it turns out that they had kept going S back toward US-36. My east road, though gravel and dirt, was outstanding and very firm for a few miles, allowing me to gain a welcomed cushion by the time I reached Burr Oak. There, I briefly stopped to examine and shoot the main mesocyclone area to the NW, now deeply wrapped in a north-Texas-style HP stormzilla.
Opening up some space between me and the rear flank also became crucial when two things happened at once, E of Burr Oak:
1. A heavy shower that had formed to the S passed directly over the road ahead, and
2. Preceding the next paved N-S option, I encountered a 2-mile stretch of the same “road”, which previously had been a deeply rutted strand of slop, and now was being rendered horrendous by the shower.
Thank God and Ford for high-clearance 4WD and the ability to use it properly. Prior practice mudding and sand-driving paid off here; lower-set SUVs (4WD or not) and any sedan would have ended up high-centered past the axles in that nightmarish quagmire. There was serious white-knuckle driving down a certifiably awful track, among the handful of worst mapped roads that I’ve experienced. I was counting the tenths of a mile on the odometer, trudging along through the viscous morass, not daring to stop lest I lose momentum, wheels flinging giant gobs of goop every which way. At least there were no other chasers on that wretched stretch…for good reason! Somewhere in that ordeal, I got brief coverage and a phone call from my comrades, but was in no position to stop and answer, requiring full-on concentration and the use of both hands for every millisecond.
Finally I emerged on to the hard, dry N-S road, likely shedding well north of 200 pounds of mud to rain and centrifugal forces as I zoomed off southward toward Mankato. One last look back N at the HP storm gusting out, then a peek at a new Cb forming to the SE, and what appeared to be a newer, elevated supercell to the W (atop outflow from the big HP), dictated the next step superbly: get SE.
Upon reaching Mankato from the N, I got back into reliable cellular coverage and re-established phone contact for a meeting E of town. By this time, the elevated supercell was moving into Mankato. Thinking we had a decent shot at a spectacular sunset on the back side of the convective mass, and that most of the core of the ESE-moving storm would clear town by the time we went back through, that’s what we tried. We tried too soon.
Skirting the N edge of the main core, we encountered mostly heavy rain and marginally severe hail, except for the large ice bomb or three that bounced high in the air off the ground. Well, a few bounced off vehicles too. They took a 3-incher to the windshield, and I heard and felt one or two really fat ones clunk the roof where decent dents later were seen. Fortunately it was over quickly, but we were just a little too hasty going in. I took the blame for this bad call, because (clearly wrongly) I thought the meat of the core was S of US-36. The Dudes, Dudette and Dogs crew were upset, and rightfully so.
Unaware to us at the time, and purely by serendipity, this would turn out to be one of the best things to happen to us all, because it forced them to limp into the nearest big town (SLN) to get a windshield replaced, effectively nixing their prior intentions to chase in Colorado the next day. Meanwhile, the sunset wasn’t calendar-worthy, thanks to light blockage over most of the sky from clouds farther W, but was beautiful and enjoyable nonetheless.
As for me, I didn’t feel like driving all the way to SLN in darkness and deer crossings, and instead got a cheap room at a little motel in Smith Center in time for a late dinner. Though this chase now will be known forevermore as the ideal setup event for the nest day’s feast, in its own right it was a fine fourth part of five in the journey of High Plains Therapy.