Strike Three (Time for New Game)

August 5, 2013 by · Comments Off on Strike Three (Time for New Game)
Filed under: Summary 

Lindsay and Elmore City OK, St. Jo TX
20 May 13

SHORT: Strike 3, batter out for this system. Intercepted 3 supercells in 3 tornado warnings and 2 states, saw no tornadoes: 1) Lindsay OK, 2) between DUC-PVJ, 3) near St. Jo TX.


Setting up “the day after the day after the day before the day”
Somehow, on consecutive Kansas/Oklahoma tornado days, we had come up empty-handed in that regard–and worse, with very few decent photos or positively memorable experiences to show for it, despite multiple storms intercepted. This third chance, a cold front was moving very slowly SE across central OK, into an air mass characterized by upper 60s to low 70s F surface dew points, and strong surface heating. Many long-time, seasoned storm observers, in their pre-chase forecast musings, targeted the cold-front/dryline triple point area, forecast to be near FSI by late afternoon. Rich T and I wanted to hang a little closer (CHK area) for starters, but as it turns out, not even that was “close” enough.

My last forecast offering before hitting the road summed up the pre-chase situation fairly well:

    In some ways, this is a messier, more difficult chase-forecasting scenario than previous two days, and we still somehow avoided all the tornadoes on them. What does today have in store?

    Could be an early-initiation scenario (relative to previous days), especially on the “northern” end of the regime from the CHK-OKC area NEward, given positioning of the upstream shortwave trough, high CAPE, rich low-level moisture and likelihood of CINH eroding fairly quickly in SSW-ward zippering fashion. This looks like one of those patterns that support fairly quick SWward backbuilding after initial mode of relatively discrete storms. Two big questions to answer today:

    1. How long will discrete mode last?
    2. Will storms go too early and get messy while the warm-sector flow still is somewhat veered, and before low-level SRH picks up later in the afternoon?

Rich and I were rather worn out from the two prior days, but decided to head out anyway, given that the threat was within a couple hours’ drive of home. By the time we left, shortly after 1 p.m., deep towers already were building along the cold front W and SW of the OKC area, and along the dryline farther SW.

What was and could have been
Migrating our way SW, we noticed two main areas of development–a multicellular splotch near FSI (later to evolve into the DUC-PVJ supercell) and a more discrete, fast-growing echo SSE of CHK, headed toward PRC. The latter was closer, moving into a high-CAPE, moderate-shear environment, and more isolated, so we migrated that way for starters. A nice vantage from just E of Lindsay offered this early view of the young storm to our WSW, still small and beginning to fall under the anvil shadow of the FSI-DUC cluster (the latter’s anvil being visible at distant left).

Had the Moore storm formed either first, or a little later (with more time to get there), we might have targeted it instead. However, it developed to our NNW near Blanchard, with a rather ragged early look for such a big-CAPE day, as seen through the anvil precip of the Lindsay storm. Being in the immediate inflow of the latter, which still held some promise of growing and maturing, we held position.

Questions about our storm’s current and future integrity arose with the dramatic sharpening of the appearance of the future Moore storm, the narrow updraft of the Lindsay supercell as it moved nearby to our NW, and the rain falling into the latter’s inflow from the anvil of the DUC cluster.

Before long, the Lindsay supercell weakened dramatically, leaving us sitting there stormless with this decision: zigzag back NNE to I-35 and try to catch the northern storm, now tornado-warned and sporting a hook as it moved toward western Moore, or head S on a more straightforward path to ahead of the consolidating and closer DUC convection, by now also sporting a radar-indicated mesocyclone and moving NE (much faster approach). Chasing in the metro area also was considered a negative; so we turned S.

Soon after doing so, we heard a frantic TV simulcast over the radio describing a growing and potentially violent tornado moving into Moore. This was terrible news on multiple fronts. Moore had been devastated multiple times in the past 15 years, and this was the last thing they should have to deal with. Secondarily, we were getting the vibe that, for the third day in a row, it just wasn’t our day to see a tornado (despite not reaching the DUC storm yet).

We still had time to do a quick turn-around and maybe catch the Moore storm after it crossed I-35; but stern-chasing a destructive event through the suburbs seemed rather unwise. By contrast, Elke, who had stayed home and was watching the event unfold on TV, was able to get a safe, in-person peek of the last few minutes of the Moore tornado simply by driving a few miles N and finding a hillside vantage (E. Franklin Rd E of 36th Ave). Some trees and terrain were in the way, but she watched as the Moore tornado (by then well E of I-35) appeared to her NW, narrowed, then roped out in wild, loopy fashion.

Meanwhile, an hour to the south, we simply had to digest the fact that we were missing what sounded like the worst central OK tornado event since 3 May 99, while also hearing a report of a brief tornado from the DUC storm that we hadn’t reached yet!

Post-tornadic DUC-PVJ supercell
Heading W out of Elmore City, we caught the former Duncan-area supercell W of Foster. Finding reasonable vantages was difficult amidst the shoulder-deprived roads, hills, trees, an abundance of both real and imitation storm chasers taking up the best pullouts, and storm structure that looked very wet and messy via glimpses through the obstructions. What was left of the main mesocyclone got wrapped in rain and lost its identity NW of Foster, as very heavy showers flooded the main supercell’s inflow region with their own stabilizing effluent. A newer meso seemed to get undercut as it crossed the road nearby, and as we experienced cold RFD outflow to its immediate SE.

Nonetheless, the storm tried, amidst all the convective-scale slop, to maintain some supercellular identity as it headed ENE between Elmore City and PVJ. This view, looking NW, was about its most robust appearance, with moderate visual rotation and a concurrent reflectivity hook on radar, before it crossed I-35 just N PVJ. After short deliberation in town, we let the gradually shrinking storm go, and plunged S on I-35 to intercept whatever would remain of a big North TX supercell located SE of SPS. It was either that or give up and crawl home in shame. Not being easy quitters, we decided to make a go of it.

Takin’ the Tejas plunge and back
Radar showed the Texas storm right-moving toward Muenster, so getting safely ahead of it would be easy at legal Interstate speeds. First, however, we had to reach to a spot just S of the Arbuckles before the front wall of a formerly discrete supercell–by now a messy storm tangled up with a large load of other convection, and dominated by a deeply rain-wrapped/forward-flank circulation. We beat that electrically active mélange of amorphous slop by just a few miles (structure so fuzzy it wasn’t worth a photo stop), then proceeded across the Red River. A left-mover we had been monitoring SSE of the storm was closing in fast, leaving us with (at best) a narrow window of potential before mutually assured convective disruption.

Turning W on US-82 aimed us toward a dramatically darkening and increasingly lightning-splashed western sky. After we left Gainesville, the former fuzzy mess that we had ignored got tornado-warned NE of ADM. That’s right–kick us while we’re down!

Between St. Jo and Nocona, we found a temporarily good place to park, as the supercell–by now an HP stormzilla into which the large left-mover already was ramming with great force–closed in. While waiting, we encountered Matt Crowther and Vince Miller, and had a short but nice chat with them.

When the approaching half of the sky looks like this, and then several minutes later, like this (notice the long line of fleeing vehicles), it’s not a wise idea to stick around sipping frosty brews and smoking Cuban cigars from the comfort of lawn chairs. Having no such suds, smokes or seats anyway (just shamefully seldom-used cameras), we high-tailed it E back to Gainesville. Meanwhile, ransacked by all the cell mergers, collisions and outflow, the formerly imposing storm became a gusty heap of rain and lightning. Whataburger time…

We ate, let the heaviest part of the cores slide by to our N, then shot the convective gap northward before some heavy, training and elevated storms reached the Marietta/ADM area. Some beautifully colored sky, just before and after sunset, greeted us near Springer. That offered but a small modicum of cool relief on part of what felt like a substantially large chase burn. By the time we rolled back N on I-35, in despair over the disaster in Moore, and with Rich’s chase vacation having ended on three straight swing-n-miss days, we were quite ready to carry out the sentiment expressed by the following quote from 2006…after all, our chances of seeing Sasquatch seemed greater at that point.

    “Let’s forget this tornado chasing and go look for Bigfoot.”

There still was some vacation time left for me, however. Soon, I would desire (and embark upon) some much-welcomed and soothingly corrective “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.