Smith Center Tornadic Supercell

November 14, 2013 by · Comments Off on Smith Center Tornadic Supercell
Filed under: Summary 

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.


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.

Millsap TX Tornado and Supercell

July 18, 2013 by · Comments Off on Millsap TX Tornado and Supercell
Filed under: Summary 

Brock TX
15 May 13

SHORT: High-based junk storms watched near ABI. Headed E on I-20 toward confluence-line towers moving into high-SRH environment. Saw eventual Granbury supercell looking S and almost went after it. Instead took direct I-20 route to explosive, then-bigger storm to our NE. Watched excellent structure, brief/weak tornado(es), longer-lasting Millsap tube, and messy/multi-vortex circulation from Brock exit. Road-screwed for both storms after that. Tried to glimpse South Dallas storm after dark, too much rain.


Pre-storm setting and early dryline convection
In a year that had been rather scant for observable tornado potential, we didn’t truly expect this day to yield much, either. Maybe it was pessimism. Maybe it was an unspoken wish not to jinx the chase, despite our disbelief in such paranormality. Maybe it was the peculiar pattern, with some split flow and the shrunken remains of a southwestern upper-level low slowly ejecting across Oklahoma. [For decades, didn’t Al Moller often extol the virtues of split flow aloft for outstanding Texas chasing?] Maybe it was the vibe that this was one of those down years (shown to be decidedly false by month’s end).

Reasonably large hodographs were reasonably forecast for part of north-central and NW TX, but generally displaced 100 miles E of the dryline, near the western lobe of a corridor of very mist return-flow air. Perhaps if an initially high-based storm firing off the NW TX dryline bulge can last long enough to get into that returning moisture and backed surface flow before dark, it could get happy. Perhaps this, if that…you know the saying: “If ifs and buts were candy and nuts, it would be Christmas every day!” Whatever the reason, we headed southwest on a classical spring chase trip to NW TX talking supercells but not tornadoes.

Rich and I decided to play the belt of enhanced midlevel winds and deep shear, S of the OK low aloft, W of the northward moisture bulge and E of the eastward dryline bulge. Initial target was the Haskell-ABI area, with (naturally) the season’s first Allsups burritos consumed along the way in Seymour. While at an abandoned farmstead N of Anson, the first deep towers erupted just to our WSW, practically in our laps and as if on queue.

However, more, even deeper towers could be seen in the hazy distance SW of ABI. Not seeing an appreciable difference in the environment of either, and both being in our target area, we decided to head toward the southern towers and keep the northern ones in view. The southern convection stayed more vigorous, and even garnered a severe warning–but turned to virga-blowing mush by the time we got S of ABI and in good intercept position to its E.

Meanwhile, the high base of the original convection, now two counties (or about 50 miles) to our N, could be seen clearly despite its distance, beyond the anvil material of the dying ABI storm. A quick check of the surface map and objectively analyzed moisture and CAPE fields revealed that the northern cell was a flimsy hope for making it far enough E to tap the reservoir of upper 60s surface dew points S and E of MWL, and (for now) shallow but building towers could be seen in the distance, corresponding to a confluence line located along the W side of the moist plume.

Maybe the northern storm somehow could get far enough east (unlikely). Maybe the cap could weaken enough along the confluence line to blow a storm or two and send it into the good juice (an intriguing but highly conditional possibility at that point). For either scenario, we would need to head back to I-20, then ENE at least 50-60 miles. If ifs and buts were candy and nuts…

As we scooted E of ABI and the northern storm shriveled, we were at our most pessimistic, as were many other storm observers–some of whom immediately abandoned the chase to start heading NW toward forecasts of central High Plains storm potential in the following days. We didn’t have that option, and besides, something very intriguing was happening across the eastern sky.

Target shift
We hung our hopes on those gradually deepening confluence-line towers–convection that got ever deeper and thicker as we rolled along the slab. The closer we got, the better it looked. The bigger towers began to sort themselves into young storms, and some of the development to our SE, ESE and ENE looked like it was going to erupt into big action very soon. The situation definitely was passing the eyeball test for those of us who have been doing this awhile.

Parameter check: effective shear was fine…SRH increasing E of the confluence line…CAPE was large, and we know what big CAPE does. Accordingly, an elongated bull’s-eye of significant tornado parameter (an index we invented, so we had better pay heed!) showed up and increased downshear from the building storms and W of I-35.

I could detect the scents of delectable convective comestibles cooking in the kitchen of the sky, soon to be placed on the smorgasbord of atmospheric violence for us to devour! The question was becoming: which entree shall we select?

By the time we approached exits leading to BWD and MWL, one healthy-looking storm already was beginning a right turn near BWD, and was warned. Two younger and closer ones were apparent and looking robust visually, but not yet as impressive on radar–approaching SEP (this became the eventual Granbury/Cleburne storm) and near MWL (the eventual Millsap storm). We had our pick of the litter, and ultimately wouldn’t have gone wrong with either of the two closer choices. Though the southern one of the closer pair initially was smaller and took longer to mature, it ultimately produced a violent tornado in deepening darkness. We briefly stopped briefly to look S at that young, future Granbury/Cleburne storm to our SSE, small but already showing some visual supercellular characteristics.

Meanwhile, the cell near MWL went berserk in ten minutes–two volume scans–explosive towers evident through intervening low clouds in the near NE sky, and remarkably rapid growth in areal coverage on the radar screen. Between that trend, the choppier terrain in the path of the much smaller SEP storm, the presence of an Interstate to take us straight to the northern storm in legal haste, and the poorer road options S of I-20, we quickly selected the MWL cell for close investigation. Along the way, and between hills and other obstructions, we saw a wall cloud quickly form and occlude (without tornado) under the base. This storm went from disorganized mess to serious supercell in less than half an hour, and as Jim Leonard might say, “This is serious business now”.

Smorgasbord delivered
Finding high yet accessible vantages in that part of north TX is a challenge; so we grabbed the easiest and first spot we could find in the storm’s inflow region — a staging area for construction work right off the Brock exit. Unfortunately, this means there is road-work material and/or the Interstate in the foregrounds of some of the images; but I guess they tell a story and add some foreground texture too. As for the storm, what a structural delight that greeted us! We remained at this spot, or just across the overpass (later stages) through the entire tornadic stage of this storm.

One fairly low wall cloud developed while the storm still had most of its spectacular deep-layer structure visible, with a turquoise tinge starting to show up in midlevels. A few minutes later, around 1841 CDT, a funnel (deep enhancement) developed on the near left edge of the wall cloud, with scud sometimes rising rapidly right off the ground and more slowly rotating into it as part of a distinct, helical column. It was about as weak and low-end of a supercellular tornado (deliberately underexposed zoom) as one can imagine, but nonetheless, there it was. This little vortex lasted just 2-3 minutes and whetted our appetite for more.

In the succeeding 20 minutes after that “wimpnado” ended, a big gob of rain slowly wrapped around what was left of the wall cloud — now becoming ill-defined — in the form of a precip-filled RFD. Then, at 1903, another funnel (deep enhancement) became apparent within the translucent bear’s cage, a little more distant from us (maybe by a couple miles) than the first vortex, and near Millsap. Though no power flashes were visible, faint and low-contrast ground contact of condensation in these early stages confirmed another tornado for us–albeit cheesy at this stage.

Quickly, the whole mesocyclone wrapped deeply in rain and completely obscured any remains or evidence of a tornadic vortex within. As such, we do not know if there is true physical continuity between that vortex and the next one in the same general area. However, this view at 1907, as the precip began abating and the mesocyclone got more deeply occluded, shows no obvious visible evidence of a continuous tornado.

Here’s the next visible vortex! This showed up suddenly at 1909 (deep enhancement), representing the start of the “Millsap tornado” that many observers watched. It may or may not have been continuous with the previous tornado. Some translucent curtains of rain still were orbiting this increasingly deeply occluded and quasistationary meso. The tornado became better visible as a classical, partly rain-wrapped cone beneath a scuddy and ragged storm-scale circulation.

Meanwhile, the parent supercell was moving slowly SE, away from the tornadic circulation–effectively kicking the old occlusion farther back through the rear of the storm. A new mesocyclone started stem-winding just ENE of us by just a mile or two, at most. We had to keep our heads on a swivel, watching the adjacent, tightening area of rotation while admiring the tornado from a greater distance.

Look here, look there…left, right…look here, look there! Someone watching a camera trained on me might have thought I was observing a slow-motion tennis match. Unfortunately, I didn’t shoot the closer meso yet because our ideal tornado vantage on the SW side of the interchange put the Brock Road bridge in the way of seeing much beneath the circulation that was practically in our laps. What a mesocyclonically bipolar conundrum! I was ready to run over or under the bridge, however, to shoot right down the Interstate in case the nearby circulation tightened to tornadic intensity.
It’s a good thing that didn’t happen yet, because the meso was smack-dab over the road to our immediate ENE, with a good deal of truck traffic zooming this way and that.

With the tornado still in progress to the NW, a brief, small funnel appeared to the N, but with no ground circulation evident beneath. The funnel sprouted from the cyclonic-shear zone (and likely ribbon of low-level vorticity) in between but connecting with the two mesocyclones. Clearly, this was a much different environment than our moisture-starved convection out by ABI.

Back on the occluded, certifiably tornadic area NW of us: the rain gradually fell away to reveal a classical tornado specimen in its full splendor, going through assorted conical forms from nearly symmetric to tapered and curved for several minutes, finally roping out with a twist. A detached condensation puff marked this tornado’s dissipating gasp at 1919, and its parent mesocyclone very quickly followed suit.

No time existed for basking in the joy of a harmless and beautiful tornado as just seen. The nearer mesocyclone actually retreated N of the Interstate, exhibiting a similar storm-relative backtracking as the precious attempt–but without the long-lasting, high-contrast tornado. Instead, it offered a short-lived, fuzzy, scuddy, ragged, multivortex circulation that lasted 2-3 minutes starting around 1922. We promptly drove the hundred yards or so back onto the eastbound service road and over Brock Road to get a better view, by which time the multivortex action to our NNE had consolidated beneath a fat little tube that was coiling ragged scud off the ground.

Fortunately, the brief tornado continued to back away from the Interstate, soon dissipating. Yet another meso was developing downshear, a few miles to our SE, as the supercell jumped flanks.

Decisions in Dallas darkness
Unfortunately, this southeastward, effectively discrete propagation led us right to the W edge of a road void ENE of Dennis, looking E at an increasingly rain-wrapped meso. We had no viable option back around to the inflow side, and no view within. A very well-defined radar hook, a tight velocity couplet, and rapid N-S precip motion on the back side left us wondering just what was happening “in there”. The precip was just too dense to see through, and the viewing angle was bad (except for the rainbow across a field of flowers).

Refreshingly rain-cooled air, tinged with a blended floral and earthy scent, carrying bird songs, was a consolation for an inability to ascertain what the later storm reports indicated was nothing of importance happening inside the mesocyclone. We surprisingly encountered Jack Beven and Margie Kieper on this remote stretch of unmarked back road NNE of Dennis; they had seen the main Millsap tornado from the distant E after a late start from visiting friends in the DFW Metroplex.

We all could have made the loopy plunge southward to intercept the now tornado-warned Granbury-Cleburne storm (whose flanking towers were visible and not far away) at or just after dark. Common sense prevailed. Core-punching a tornadic supercell, from the N or NW, on twisty and hilly roads with few escape options, in deepening darkness, did not appeal. Instead, Rich and I grabbed dinner at Whataburger in Weatherford, then headed back toward FTW for the turn northward and homeward.

Along the way, a small supercell with a nice hook erupted over Arlington and cruised E across the Oak Cliff section of SW Dallas. meanwhile, the Granbury storm was headed ESE toward I-35 and could have been targeted (again, we decided against that). Though it was dark, the projected path of the smaller Dallas storm took it toward south Mesquite; so we jumped down to I-2o to get into its inflow region. Very shortly after doing so, we encountered a huge traffic jam…going the other way! A wreck had the westbound Interstate backed up for miles; but our side was smooth sailing. Before we got into decent position SE of the storm, though, a dense cluster of heavy showers formed and moved right over us; their outflow weakened and ultimately killed the south Dallas supercell. We turned N through its feeble remnants, wheeled around LBJ freeway and drove on back to Norman through occasional elevated storms.

A north Texas chase day finally bore fruit for us with a classically structured supercell and a few low-impact tornadoes casually observed from one spot. The bad news was that the storm we didn’t chase (and wisely so) produced a terrible killer tornado near Granbury, and a big, destructive wedge after dark, around Cleburne. This marked the sad day that the switch had flipped on from a shockingly inactive tornado season to a dreadfully busy and tragic two-week stretch, at least for the southern Plains.

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