Elaborate Tornado Avoidance Techniques

July 27, 2013 by · 2 Comments
Filed under: Summary 

Southern Kansas to east-central OK
19 May 13

SHORT: Intercepted 4 supercells in 3 tornado warnings and saw no tornadoes: 1. NW of Ark. City KS, 2. near Parkland OK (middle storm of OK triplets), 3. ENE of Prague, 4. Near Okemah and Okmulgee. Somehow managed to miss all the tornadoes two days in a row.


Setting up “the day after the day before the day”

Having intercepted clearly the most unfavorable of several Kansas storms the previous day, the “day before the day”, Rich T and I were determined to get on a tornadic supercell on “the day”.

A classical setup set up for the corridor from southern KS to central OK, with rich low-level moisture return, a strong dryline, a lack of antecedent precip to mess up the boundary layer, large low-level hodographs, and strengthening deep-shear vectors with a decent component across the dryline. In short, this was a prime southern-plains tornadic-supercell regime, the only potential hitches being mode certain initiation with storm-mode concerns up north (near a cold front) and initiation questions farther south.

Our strategy, therefore, was to get in between the two ends and be in prime position to strike like a predator at the best developing storms in a corridor from OKC-ICT. We arrived early at a truck stop N of Perry and awaited development. Early storms near ICT looked interesting, even supercellular and potentially tornadic, (one did produce there), but also, potentially tangled up quickly in a messy cluster near the front. Fateful decision #1 had been made: blow off the early, tornadic ICT storm for more discrete and ostensibly longer-lasting activity to form closer, later.

Two areas of convection began to develop almost at once: just W of us, moving NNE toward Wellington, and about 75 miles SSW of us, on the NW fringes of the OKC metro area. Either was easily reachable. We had much better visibility on the closer activity, which seemed likely to remain in a favorable environment well into mature stages. Fateful decision #2 was sealed: check out the closer storms, which would take us away from central OK. We had seen this picture play out several times before–jump on middle or northern convection only to have the southern storm near OKC produce tubes (whether or not we would see one with our convection). Still, we risked missing something closer to home for something closer to us.

(Somewhat) northern play

Fully aware of that dubious history, we headed N to near Blackwell and took a look at the growing Cb, already showing some supercellular characteristics on radar–as did an initially separate, trailing storm behind the cold front and to our storm’s WSW. This is how it looked before the base came into view. We hopped N of the border, zigzagging E and W a little across I-35 N of Wellington to get in viewing position. The storm turned out to be a messy HP with poor contrast. Only a brief, surging attempt to wrap a mesocyclonic occlusion was visible, with a funky, spiked, ground-tickling tail cloud, before it buried itself deeply in rain again.

Optimism wasn’t the word here. The storm had 1) accepted a cascade of percip from the dying remnants of the post-frontal supercell, 2) dealt with big towers and showers forming and merging into its rear flank, and 3) interacted with a new, quasi-linear frontal segment nearby. Meanwhile, radar showed the storms near OKC coalescing with frightening speed into a big, honking supercell near Edmond. This is when we started getting that sinking feeling…here we go again.

Back to central Oklahoma

Fateful decision #3 actually didn’t take long: let’s not linger with this HP rubbish, and try our best to bust SSE ahead of the now violently tornadic convection just NE of Edmond (or anything that might form farther upshear). We didn’t dither on this, which made an intercept from that distance at least marginally feasible. Somehow, the at HP rubbish, and accessory convection building into its flank, produced a small but photogenic tornado near the South Haven exit of the Kansas Turnpike…not long after we left!

Unaware yet of that morale-crushing development, we made decent time southward on US-77/177 through PNC to the Cimarron Turnpike, then SE on the speedy slab. All the while, we could see the booming, huge flanking towers rolling into the back side of the leading storm, now near Stroud, with a known history of atmospheric violence. However, as we closed in for a potential end-around the back side, potentially in the Bristow/Kellyville area, the convection was softening, the mesocyclone weakening, the storm moving into somewhat cooler, lower-theta-e air.

Resigned to missing all that storm had to offer, we saw two newer supercells on radar, and fuzzily from the sunny N side–a small one to our near SSW, near Carney and trailing behind the first. The westernmost storm was organizing fast…over Norman! That was the cell we really wanted to see, with its unimpeded inflow and longer prospective resident time in juicy air…but the middle storm (which was sucking some outflow from the formerly tornadic lead supercell) was smack in the way.

Since the middle storm was considerably smaller than the others, with lower VIL and MESH hail indicators and a thinner forward-flank core, we made fateful decision #4, hedged a bet against the risk that could strengthen its hail production, and headed S through its forward-flank core toward the Agra/Parkland area. True to its algorithmic evolution, that core indeed contained only marginally severe hail and was surprisingly translucent, allowing us to pop out of precip a safe distance of 4-5 miles ENE of the storm’s mesocyclone. We could check this out briefly while plotting a course to get ahead of the Norman storm, by now producing a tornado over Lake Thunderbird–just a few miles from both my house and Rich’s. That sinking feeling came back again.

Yet we weren’t obligated to leave this storm just yet, not with us in an unusually good vantage point for this hilly, forested part of the central Oklahoma crosstimbers, and a tightening mesocyclone approaching rapidly on track toward a spot on the highway immediately to our north. From a distance, the main cloud area was so low that it might have appeared tornadic, but we certainly were close enough to confirm otherwise. As it crossed less than a mile away, the persistent, deep, scuddy lowering was rotating, but not especially fast, and had no debris or dust beneath. Inflow felt rainy and somewhat cool the whole time, which seems to have been more related to the earlier storm than this one. Nonetheless, it tried hard (deeply enhanced crop)…just not hard enough.

Having spent just a few minutes examining that supercell, we made our expected run for the former Norman storm, now approaching Prague, offering a tremendous radar signature, and yielding terrible media-broadcast tales of tornadic destruction from the Dale-Shawnee area. By the time we got to I-44 and US-377, it was obvious we would have to either: 1) make a big zigzag to take a safer approach, or 2) penetrate this storm’s forward-flank core too, but come out perhaps even closer to what was known to be a dangerously tornadic mesocyclone on 377.

No, thanks…fateful decision #5–live to chase another day! I don’t know what would have happened had we turned stupid and tried to core-punch that sucker, but I’m glad not to know. Even though the NWS tornado mapping for the event shows a break at 377, the risk was too great…and of course gorilla hail can take out a windshield and end a storm intercept quickly. Notice also the tornado path NE of Prague, between there and Welty (the W road E0960 off OK-48, halfway from Bristow to I-40).

Zooming safely ENE on I-44 then S on OK-48 toward Welty, we passed instead through far-forward-flank precip that was dense but only rain. We passed through hilly terrain near Welty and hunted for the first relatively open view of the big supercell that wasn’t right in the path of the meso. By the time we saw the storm, looking W on side road E0980 S of Welty, it was a deep, dark, low-contrast, HP drum. The storm definitely was producing a tornado at the time based on official mapping, but one we just couldn’t see with our eyeballs because of extremely dense wrapping precip. At the time of the last shot, the tornado would have been directly down the road, in the distance (deeply enhanced crop).

Shortly after I walked a little way down the road to try a different angle (deeply enhanced crop), a small car pulled up. The unknown chap inside noticed I was shooting the storm, and started an impressive routine of big-timing, offering instruction about the supercell’s structure and what was going on where. His descriptions were fairly accurate in a general sense, but this presumptuous little game was wasting both of our times and just had to stop. I’ve seen and studied a supercell or two myself over 28 years of storm observing and professional meteorology, so it was hard to resist temptation to bust out laughing. Instead I decided to have mercy and let him off the hook relatively painlessly. Once I could get a word in edgewise, I succinctly discussed the likely pattern of vorticity lines around the wrapping, precip-filled occlusion downdraft and its interface with the forward-flank gust front of a supercell of this configuration and morphological stage. [Thank you V.O.R.T.EX.] Quickly my interlocutor quieted down and turned his attention back to the storm. 🙂

Duly amused and a bit grateful at not being recognized, and not wanting his vehicle (or its glare) to take up too much of the shot, I wished the dude good luck, and jogged back up to the vehicle. Rich (who had stayed by the vehicle) and I watched hard for any evidence of the ongoing tornado somewhere in there (deeply enhanced crop). The rotation of the precip cage and surrounding cloud deck was impressive, but we still couldn’t see the tornado by eye. Even the deep enhancement leaves room for doubt.

After that, the visual appearance got even messier, the mesocyclone shifted NW then NNW of us, and RFD precip began to hit. We bailed S, glancing back at the remnant circulation crossing behind us (by then nontornadic, as it turned out) expecting that to be our last view of the storm in the fading daylight. An awful lot of rain was falling well S of the hook of our previous supercell, and once we got out of a cell-phone hole and saw radar again, it was obvious why. Yet another supercell had gone up farther SW, playing a game of mutual hindrance with the former Norman-Shawnee-Prague storm. They were aligned in ideal geometry to dump rain and/or outflow into each other’s inflow regions!

Enough was enough

Despite its ragged and somewhat high-based appearance (looking NNE from near Castle), we followed the last supercell N a few miles out of Okmulgee before twilight and unimpressive structure mercifully ended the intercept. Somehow we had witnessed four supercells and no obvious tornadoes on a big-event day, and aside from that, had seen very little in the way of photogenic structure. On top of our chase failures the previous day, this dealt a most demoralizing blow; and that wasn’t the worst of it.

At some point in there, I learned that the beloved cat Iniki, who suddenly had fallen ill a couple of days before, had to be put to sleep by an emergency veterinarian the same evening, while I was out driving hundreds of miles and failing to see anything of note. I never got to hold her and say goodbye. This day officially sucked. How could doing an activity I loved so much get so stinking miserable?

We ran into Bobby Prentice and Scott Fitzgerald at an Okmulgee gas station, hearing of I-40 being closed on our way home due to tornado damage (indeed, it was). We didn’t need more bad news. Yet, to make matters worse, we then learned that the Shawnee tornado had been a killer, and also, crossed the power-supply lines N of Rich’s house and cut electricity thereto for many hours ongoing. His food was unloaded into my fridge and big freezer, and he stayed at Elke’s and my place that night.

Our wish for the 20th was to turn the heretofore painful storm-intercept fate of the previous two days around on the third and final day of this weather system, despite fighting the urge not to even bother…

Supercell Four Play

December 30, 2012 by · Comments Off on Supercell Four Play
Filed under: Summary 

Northeast South Dakota
17 Jun 12

SHORT: Very enjoyable chase day. Saw 4 supercells, each photogenic in its own way, each with its own distinctive personality.

Two days prior, Matt Crowther had accompanied us for a pleasant storm-photography jaunt across western SD, followed by a wonderful day in the Badlands, and then…this fantastic end to the storm-intercept parts of our vacations. Truly, it was a tale of four supercells.

Prediction and Positioning
Multiple days of large convective volumes over the southern Plains had left the trajectories feeding northern Plains systems rather moisture deprived. This was the first day in many where we would get at least a narrow plume of at least marginally favorable moisture for robust supercells, beneath strong flow aloft that was likely to be aligned nearly orthogonal to the main frontal zone. Strong capping farther south limited the prospective action to a chunk of land covering mainly northeast SD, perhaps creeping slightly into MN before dark.

Targeting that area from a start in PIR, we headed N and E toward a general storm-initiation prediction of ABR. Along the way, we stopped to photograph a pretty cirrus scene above one of the glacial lakes, along with a couple of farmsteads abandoned to cryptically artistic decay as well as to the risen waters of a natural lake.

After fueling in Ipswich, the heading N several miles, we noticed two areas of deepening cumuli and occasional fatter towers:
1. To our SW, generally in an elliptical area corresponding to the slow-moving frontal zone, and
2. To our ESE-S-SSW, along a differential-heating zone rendered by the S edge of a persistent mid-upper level cloud deck.

Both regimes were in the target zone, so we zigzagged back toward the N side of ABR as towers kept deepening. Finally, as we got back under the old differential-heating zone, several storms went up basically at once, in several directions. The “cleanest”, most promising-looking, and least impeded by neighboring activity was a cell to our WSW, W of ABR. It offered tumultuous tidings to that fair city should it turn rightward.

Aberdeen Supercell
The storm aiming for ABR seemed in optimal positioning–near the union of the two initiation regimes, and well-located with respect to potentially rightward-deviant motion directly along the differential-heating boundary (and any vorticity generated thereon). As seen looking W from just N of the WFO (which is on the N side of town), the new storm quickly assumed visual supercellular characteristics, then moved in our general direction. A more newly formed, upstream cell was casting some of its own downshear precip into the flank of the supercell, making it somewhat messy and HP in character.

As the forward-flank and vault regions began looming overhead, we headed S and E out of ABR to avoid dealing with town traffic in heavy rain and hail. E of ABR, we stopped to look back toward the storm, now sporting a well-developed wall cloud that was weakly rotating; meanwhile, large-hail reports became part of radio chatter from the area under the storm.

Pacing the storm eastward on US-12, in stepwise fashion, we noticed that the mesocyclone region experienced a disorganizing phase, then reorganized into a beautifully striated stack. The storm still was plagued by a bit too much precip, and ultimately paid the price by gusting out near Groton. This would have made a fine and worthwhile chase day anyway!

Peever HP Supercell
Keeping ahead of the self-destructive ABR storm, we mulled our options, increasingly confident that we could use US-12 as a vector to outflank a dark, murky storm above the ENE horizon that radar indicated to be a large, HP supercell. Why not? There still was plenty of daylight and an abiding curiosity in what the other side looked like. We’re so glad we did!

By the time we outpaced this supercell near I-29, it storm was tornado-warned, with a major mesocyclone evident in velocity imagery, but a dark and dense-looking wrap-around core apparent visually. We wanted no part of a bear’s-cage penetration of this somewhat fast-moving storm, so we stayed back to observe and photograph its striated, menacingly elegant cloud forms. Here’s the other side looking WNW, as seen from just E of I-29 near Summit, and looking N toward the area near Peever, as seen from between Marvin and Milbank. In the last shot, the curvature of the farm road nearly mirrored that of the supercell, lending a fortuitous and much-appreciated composition.

The storm’s structure became more fuzzy and outflow-dominant after that, while precip from still more storms forming to our SW began to fall. We headed S out of Milbank to clear as much of that precip as possible, concerned for the future of any new storms due to
1. The outflow surge from the big complex gathering to our N, and
2. Impending sunset with related loss of insolation-driven surface diabatic heating.

First Clear Lake Supercell
Storms to our SW didn’t look too impressive on radar, and were hard to see due to intervening precip. At that point, Matt and we agreed to split up, since he had to be back in ATL in another couple days, and we seemed done for the day.

The atmosphere had other plans. Though out of ready range of communication via hand-held portable radios, we independently headed S of Goodwin and W of Clear Lake, staying reasonably close as one of the southwestern storms took on a supercellular appearance, its base getting more circular and striated with each passing minute. The brief wall cloud in the last shot went away, however, and the storm became somewhat higher-based as it moved to our N.

Obviously destined to be nontornadic, the supercell nonetheless put on one final, fantastic show of structure, leaving us thoroughly bedazzled (and once again wishing a specific and exceptionally deep appreciator of such atmospheric beauty–the great Al Moller–could be there to see it!). This storm, beautifully sculpted as it was, always seemed to be sucking too much of its own forward-flank outflow. Finally, it couldn’t take any more low-theta-e abuse, and quickly became elevated and weakened.

Second Clear Lake Supercell
As we watched the first supercell shrivel and wane…lo! What had we here?

Along came another. A somewhat distant and previously unimpressive-looking final storm got organized rather quickly in the sunset light, sporting a variably ragged wall cloud and obvious storm-scale rotation, while merrily ingesting a plume of warm-advection recovery air behind the prior storm.

We felt the inflow get warmer as the final supercell drew nearer, then moved abeam to our N, offering a spectacular scene of a striated storm spraying red rain. Without dense precip to obscure our view of this classic supercell’s base, we remained in place and let the storm move to our NE, its newly reorganized wall-cloud region nearly ground-scraping at times, albeit with only slow rotation of the low-scud. Tufts of color tickled protrusions from the storm’s base as an RFD cut around the near (back) side, and a clear slot matured. This was about as close as the storm ever came to producing a tornado, but even the tightest rotation never was very intense visually.

Zigzagging generally eastward, we dropped to the edge of the Coteau des Prairies escarpment and then let the increasingly disorganized supercell go. The messy storm receded eastward into both MN and the deepening twilight, a fading and cloud-filtered alpenglow from high above casting subtle pastels across the landscape. We appreciated a brief splash of post-sunset color in the northwestern sky, then headed into ATY for the night.

Any one of these splendid storms, on its own merit, would have justified a green stamp of success on this storm-observing day. We were blessed with all four of them–essentially, four chase days in one! This was a good thing, for it turned out to be the last of the trip. A casual, three-day drive south to home (with side excursions for sightseeing) would follow, ending the Edwards’ 2012 Great Plains sojourn. Those would be our last supercells seen until one autumn storm on the way to a Colorado vacation.

Southwest Oklahoma Classic-HP Supercell

May 16, 2012 by · Comments Off on Southwest Oklahoma Classic-HP Supercell
Filed under: Summary 

Hollis to Apache, OK
13 Apr 12

SHORT: Chase route GCK-LBL-HHF-LTS-OUN. Intercepted occasionally photogenic supercell from inception near Hollis to N of Duke, then as it got absorbed into what became an HP “Stormzilla” NE of LTS that crossed Wichita Mountains. Activity forming SW of that merged/absorbed it after dark N of Apache.

The day before turned into a storm-free “bustola” on the western Kansas dryline, with only distant convection to the north near sunset. Elke and I salvaged something from the 12th by heading to Monument Rocks for the late-afternoon light, then bunked down in GCK.

Today’s most straightforward storm intercept target was over the NW TX, SW OK and SE Panhandle region near CDS. We left GCK for a long but simple jaunt SSE down US-81, with lunch in Perryton. While there, storms already started firing over central and SW OK. Early initiation stinks, especially when the observer still is over 150 miles away!

A distant line of building convection hovered just above the SE horizon as we headed out of Perryton. Now we targeted the area of its prospective backbuilding into the slowly retreating late-afternoon dryline. The pre-dryline baroclinic zone upon which the storms were forming was supposed to retreat N also, after 21Z. My thinking was that the future western storms would represent the latest, highest-CAPE development, farthest removed from the threat of interference by upshear convection.

Given our distance and target area, we obviously missed the Norman tornado, not that we would have targeted specifically that needle-in-haystack HP supercell event anyway. As we reached Wellington, big towers began to backbuild on the pre-dryline boundary toward the Hollis-CDS area; so we turned E on US-63 into SW OK to get into position. We fueled up at Hollis as a young storm began rotating ESE of town, and newer convection with cores formed to our S-SW near Vernon and CDS.

Using phone radar, I noticed a nasty-looking hook had developed on the W side of Norman, with an HP supercell attached to a larger cluster of storms extending westward. It was a mess, but a mess with a meso. I called my daughter, who told me she just had experienced a tornado at the high school and had been safe in a windowless room, under a desk. The first concern, and relief, was that she was fine. My son was elsewhere, well SE of the path. Both were OK, so I could shake my head and marvel at the truth that, once again, a tornado had occurred in Norman with me observing other storms far away.

We cruised E out of Hollis, preliminarily targeting the storm to our ESE, but with a contingency to stop and let the newer development to our SW (then the tail-end conceptual target) come toward us if it started looking good. That’s exactly what happened. CGs from the newly organizing, tail-end convection slammed all around us between Hollis and Duke. We turned N out of Duke, found a good vantage 3 N of Duke, let the disorganizing eastern storm move away to our NE, and watched the newer storm approach and strengthen.

Alas, still more convection formed upshear, but the storm began looking distinctively supercellular as it crossed the section road to our W. This would become the Altus-Apache supercell, but not before producing a nice wall cloud, one with strong rising motion but only modest cyclonic turning. Another lowered area, likely from an older occlusion visible in the last windmill shot, loomed in the background.

Neither got any better organized; indeed, the entire storm started looking somewhat strung-out. We considered breaking off and heading toward the newer activity W of Hollis and W of CDS, as some others already were. However, we needed a pit stop in nearby LTS, while the supercell began turning into a dark, menacing, precip-filled mass to our N. We decided to stay with it for awhile, watching what by now was an HP “Stormzilla” over the western nubs of the Wichita Mountains.

Our supercell developed a nasty-looking HP hook on radar with a deep, intense mesocyclone; but we couldn’t see anything in the dark murk from LTS regarding the tornado report near Blair. Even without the bathroom break, I’m not sure we would have been able to get in position to see much.

By the time we reached Snyder, it was to late to do much with the western convection before dark. We also knew that the storm would head into an awkwardly configured road void in the Wichitas, cutting us off. [I had circumnavigated the void successfully last November 7, but from a different angle. That day, I beat the storm. This day, the storm would beat me.]

Driving several miles N out of Snyder, we hoped to see whatever the storm had to offer before it got into that road void. Here was its S side, along the rear-flank gust front looking W. Here was the E side, looking NNW toward a small but slowly rotating cloud protrusion with a clear slot. That looked interesting for a few minutes, until being undercut by a massive surge of the heavy precip-loaded RFD.

The photogenic HP storm moved off into the road void to our NE, and we knew it would be dark by the time we could get through Lawton and go N toward Apache to see the storm again. The storm produced a rainy twilight tornado during that interval when we were repositioning, fittingly enough.

By the time we reached Apache to see what was left, we found a storm still supercellular but again messy. Our viewing timing with respect to the best-organized stages simply wasn’t working out. At least, for a short time, the downshear anvil region sparked mightily and beautifully overhead. Our last decent wide-angle view of the storm, from a hill just E of town, featured the lights of the wind farm and Apache to our W, what was left of the wall cloud and main updraft region near center (NW), the vault area to the right (NNW), and of course, cows.

Before the storm could cut off itinerary options again, we headed NE toward Chickasha and home. The storm merged with convection to its W, evolving into a small bow, then moving over Chickasha and toward the Purcell/Pauls Valley area a weakening blob of rain and occasional hail. By then, we were home, tired from the two-day, thousand-mile trek, but eagerly anticipating the big severe-weather day of the 14th.

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