Melting Hail and Singing Frogs

May 1, 2013 by · Comments Off on Melting Hail and Singing Frogs
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Mulhall to Stillwater and Ripley OK
14 Apr 13

SHORT: Intercepted marginal/intermittent supercell–pretty storm–between Mulhall and Perkins OK.

LONG: Another day waking up during the late afternoon, after a night shift, offered a conditional opportunity for storm observing. In a year already shaping up to be sparse for such activity, this day offered at least marginally suitable wind and moisture profiles along or near a cold front, somewhere between OKC and southern Kansas.

One major concern was that any storms forming along the front, near and N of the KS border, would be undercut by the frontal air mass; so I played wait-and-see with shallower convection to its south. Finally, a clump of deep towering cumulus became apparent on visible satellite imagery NW of OKC, giving that look I’ve seen many times before of an incipient storm genesis area. Seeing that, I plotted a likely storm-motion vector that would take any resulting activity across I-35 W of SWO, threw the gear into the vehicle, and zigzagged to the Interstate to engage the prospective quarry.

As I passed downtown OKC, I could see deep towers to the NNW-NE glaciate. Radar reflectivities showed growing echoes in the same area, the spawn of the upward-motion zone responsible for those early towers. By the time I got to the high overlook near Mulhall, a series of mostly high-based and small (but deep) towers to my WNW-W were evolving into a more discrete and distinct storm.

From even these early stages, the storm was pretty, but had a pronounced core plummeting through the middle that limited the size of the upshear part of the updraft. This general configuration continued throughout its remaining lifespan, although the updraft did grow appreciably as it approached I-35 and moved into higher-PW boundary-layer air. I headed E to SWO a.k.a. Stillwater a.k.a. Stoolwater, then as the storm assumed marginal supercell characteristics, dropped back S toward Perkins to let it approach. The storm was high-based as expected, outflow-dominant, still with a small updraft, but severe-warned due to hail.

Knowing the tornado potential was next to zero, I let the rear-flank downdraft pass overhead then followed along behind the storm for a potential sunset view. In the Ripley area, still on the back edge of the rear-flank core, I encountered some hail up to about 8/10 inch in size, and reported that via the NSSL-PING app. A garishly painted tour vehicle zoomed east, into the core; but I opted for the colorful side of the storm, spread out beautifully across the eastern sky into which its slowly shrinking form receded. The earlier high-PW air began to be offset by diabatic surface cooling, and the storm spun down from the Perkins area eastward.

Cool, earthy aromas of fresh rain, melted hail and slightly pounded vegetation was welcomed by a chorus of frogs–something very seldom heard in these parts during the past couple of hot, drought-inflamed years. This was the full-sensory experience of storm observing, where even the feel and taste of the air was fresh, clean and wholesome.

After relaxing and enjoying the experience for a spell, I headed back through Perkins for a quick bite of fast food, then S down US-177, I-40, OK-102, and OK-9. It was a fun “backyard” chase that was most welcomed, while still getting me home in time to spend some time with my daughter and beautiful bride (who stayed home) before work.

Storm Observing Drama in Four Acts

July 28, 2012 by · 2 Comments
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Southeastern WY near Cheyenne
7 Jun 12

This storm day was striking in that it unfolded as a four-act drama–each one quite distinctive, essentially a quartet of distinct chases in one day. Seldom have I experienced so much logistical and emotional ups-and-downs in such a small area in one trip! We went from intense frustration to elation and satisfaction, with one or two minor dollops of danger thrown into the storm-intercept recipe for good measure.

Act I: Early Poor Decisions and Frustration
Elke and I targeted southeastern Wyoming for the potential of a supercell or two forming in a region of decent upslope lift . As we headed W from Pine Bluffs WY toward CYS, a storm formed in the Laramie Range and stem-wound itself into an intense supercell while still in high, rugged terrain. It turns out that storm formed as a pyro-convective plume off the Cow Camp wildfire, and became tornadic while still sucking smoke up in the mountains.

[NOTE: The write-up in that link does contain one major error–tornadoes cannot “skip”. By definition, if it’s “not on the ground the entire time”, it’s not a tornado the entire time! As such, each segment had to be a different tornado.]

We arrived in CYS intending to head N on I-25 and intercept that supercell, or whatever was left of it, somewhere not far N of Chugwater. Then a new storm exploded into the Wyoming sky just to our NE. A bit of indecision followed, before we made the fateful choice to take a look at the younger cell. The storm farther away looked better on radar, but the new one was right there! How do you blow off a storm blowing up practically in your lap? We should have. This move ultimately cost us any shot at a decent view of the Wheatland/Chugwater tornado(es).

We headed the short distance back E toward Burns and then N, finding that the newer storm was shriveling, while the fire-generated, tornadic supercell to the NW still was going (and still had a likely tornado, given its radar signature). I was not happy. Still, zooming up US-83 toward the west turn to Chugwater, we thought we were in great position to intercept the big supercell while still tornadic. Indeed, given the official timeline for the event and our terrain-truncated vantages, Elke and I are now sure we caught some glimpses of a cylindrical, mostly rain-wrapped tornado just over the high ridge line in the distant WNW, while driving.

I turned the vehicle W on WY-314, seemingly in ideal position to catch the end of the tornadic stage, and then about 8 miles along…a one-lane road, pilot-car closure with no pilot car! This was about when it seemed that our chase day just wasn’t meant to be. One lone lady in an orange vest was standing there with a flag, stopping all westbound traffic–most unfortunately, in about the lowest bottomlands where neither she or we could see diddly-squat.

Diddly-squat, in this case, consisted of a tornadic supercell and its approaching forward flank. We told her about the storm, its likelihood of lightning, skull-cracking hail and flash flooding…but she seemed oblivious, and totally dependent on a radio dispatcher who was (quite irresponsibly) giving her no information at all about the storm. She finally assured me she would crawl into a nearby tinhorn if it “got bad”–which wasn’t much assurance with regards to her safety. Other than that culvert, there was nothing out there in which to take shelter! Alas, that was the best I could do to convince her she was in potential danger.

Thus thwarted, we turned around and headed E and uphill several miles, finally getting a view of the storm’s base less then 7 minutes after the tornado is on record as dissipating. [Without the closure, we easily would have gotten on the plateau E of Chugwater in plenty of time to see the last moments of the tornado, across a flat and unobstructed landscape.] The supercell appeared to be getting more disorganized, with newer development to the SW…so we headed back E to US-83 then SSW toward CYS. That turned out to be the first good maneuver we made all day!

Act II: Storm Structure Bliss
As we approached the newer storm, more and more chase vehicles appeared beside and on the road–the only decent road around for miles and miles. It was easy to see why–the storm erupted SE of the first one, right along the way for a lot of observers from Colorado and elsewhere who were zooming up toward the Wheatland storm when it fell apart. By contrast, we came around it from the NE and E, found a vantage to let it move toward us, and marveled at how the structure was getting better and better as it drew closer and closer.

The main updraft base sported a persistent, broad wall cloud with occasionally fast rising motion on the downshear (core-facing) side, but never anything I would call rapid or tornado-like rotation. Meanwhile, the storm-scale formation assumed a sweeping, curvaceous stack across several layers in the vertical.

With a dearth of road options in the general direction of storm motion (SE), we kept letting it come our way until the wide-angle lens needed switching from 24 mm to 17 mm. At one point, I recall telling Elke that I wished I could teleport Al Moller here–he would go absolutely euphoric over seeing this storm in person!

The old wall cloud and mesocyclone area began to assume a more shelf-like appearance as they passed our location, and the entire storm looked a little more disorganized. The only roads back ahead of the supercell led through the core; so we had to retreat away from it in order to reposition.

Act III: Outflow and Hail Machine
We went SW down US-85 and I-25, around CYS, then back E again, then S of I-80 between Burns and Carpenter, for an encore look at the increasingly messy storm. Another supercell also had developed to its east, its updraft base cloaked by precip for the time being; it was menacing Pine Bluffs.

We pulled onto a side road to observe the onrushing maelstrom, greeted by a big, very friendly and rambunctious chocolate Lab, muddy-legged but healthy and well-fed. He probably belonged to a farmstead about half a mile away. The pooch took a running, leaping jaunt through my vehicle and out the other side before we shut the doors! If you ever are traveling with me and happen upon dog-paw prints, that is the reason. He hung around nearby for a spell until the storm spooked him back toward home.

Since we had left it NE of CYS, the western supercell had become more elongated, with a somewhat surfboard-shaped base. Since it was riding its own outflow, this was appropriate! As that storm approached us from the northwest, the Pine Bluffs supercell weakened, shed some precip, and became higher-based. It also trailed a beautiful rear-flank arc cloud that curved right back into the updraft region of our storm (wide-angle view looking E).

Dropping S somewhat to get late-day light under the rear-flank gust front region, we had a decision to make: stay apace and just ahead of the increasingly messy storm and its neighbors southward into Colorado, thereby missing an opportunity for sunset light on the back (NW) side, or go for the colorful view. We usually choose the latter in such situations, and did here, with ease. What wasn’t easy was deciding how. The updraft and main core area each appeared to be weakening some, so one way was to head straight N through the precip and back to I-80. The other was to go W on an unfamiliar road zigzagging along the crest of the Cheyenne Ridge, and hope for a good view before reaching Cheyenne itself.

We chose to attempt the former, and if the hail started getting big, backtrack and do the latter. Just a mile or so into the precip core, we hit a very sudden wall of severe hail that started beating the hell out of the vehicle, somehow sparing the windshield. Spiked bombs of ice bounced high off the road, splashed in surrounding mud, and created sickening booms as they slammed into the metal skin above. So much for the “weakening” core!

Even the quickest of Bo Duke-style turnarounds on an empty road, in a vehicle that is not quite as nimble as the General Lee, couldn’t spare us from its first easily noticeable hail dents. I blasted back S and got out of there before the beatings became worse, then headed W out of Carpenter on Chalk Bluffs Road. We’re so glad too, and not just to avoid demolishing the outside of our ride…

Act IV: Amazing Stormy Skies on the Cheyenne Ridge
Eager to escape the ice monster, we bolted 12 miles W and NW on the road from Carpenter to Cheyenne, the stopped at a very nice 360-degree vantage for one last look back SE at what had tried to turn my finely tuned storm-intercept machine into Swiss cheese. The hail core is at left in the last shot. Yes, it was still a supercell…so what, and good riddance! It was almost time for sunset magic.

But wait…what happened to the sunlight that had been behind the storm we just got behind? All manner of cloud material had developed and masked much of the sky to the NW and W, and a small, left-moving storm was moving from my SW toward the NNE…dragging its precip core toward us. Furthermore, it was rather stinking cold up there on the High Plains ridge–low-50s temps and windy from the supercell’s torrent of outflow!

Just as I despaired over this seeming state of misfortune, two glorious happenings made our day. A mammatus field to our NE, its sunbathing not blocked by clouds, came aglow brilliantly for a few minutes, while casting reflected, bronze-toned front-light onto the landscape to our W.

Meanwhile, the left-mover to our WSW drew closer, strengthened, and unloaded a protracted, stupendous salvo of high-based, cloud-to-ground lightning strikes for many minutes more! Set amidst the warm chromatic ambiance the setting sun, the scene soothed the soul, even as sharp thunderclaps boomed across the miles of chilly High Plains air. Electrical jabs blasted to the ground, truncated up in the air and jolted forth at closer approaches, until we finally had to abandon our post
for safety’s sake.

Heading westward between Campstool and Altvan, through the edge of the left-mover’s translucent core and toward CYS, we encountered a second barrage of hail. Most mercifully were no bigger than dimes, but it was very hard and noisy. Leaving that barrage, our minds were firmly fixated on securing lodging and a hot meal, when a window of amazing color and light briefly opened in the southwestern sky, as if magically. The haunting vista seemed as if we were peering out from within a cave of darkness at an extraterrestrial world light-years removed.

Epilogue: Dinnertime Hailstorm
After getting a motel, we found a Perkins near downtown CYS that still was open, and headed in for a supper that was late, but most welcomed, after a day of wildly fluctuating fortunes out on the road. As we did so, I saw lightning flashes outside, then flipped on the phone radar to see that a high-VIL core was almost upon is from yet another elevated left-mover. The resulting heavy pounding of small hail reverberated through the building, as a small flash flood washed down the low spots. Drifts of the stuff washed through the parking lot and against the wheels of my vehicle–all for our entertainment.

Our third encounter with a hail core was the most fitting way to end the storm day! Everything we had seen since leaving the destructive supercell supported the ideal that long after the main supercellular action concludes, the storm-observing day can proceed with wondrous and spectacular results. For all the lackluster results of the previous day’s storms, this one made up in multiples. Moreover, as of July 28th (this post date), we saw more rain in half an hour in Cheyenne than in Norman during the nearly two months since.

Bleeding the Turnip: Optimized Success in a Marginal Setup

July 15, 2012 by · Comments Off on Bleeding the Turnip: Optimized Success in a Marginal Setup
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Okeene to Richland OK, Tuttle to Newcastle OK
29 May 12

SHORT: Intercepted entire life cycle of eventual Kingfisher-Piedmont supercell and its tornado, as well as twilight phase of separate supercell near Tuttle.


Nowcasting through initiation

After forecasting the potential for supercell initiation in a meso-beta scale confluence zone, somewhere between the west-central part of the KS/OK border and southwestern OK, Rich Thompson and I set out for the middle-ground target of the Watonga area for what would be our last Two Chumps chase of 2012.

The low-level moisture field over central/southern OK, in the prospective upstream fetch, had been eroded and fragmented by prior convection, so LCLs and cloud bases promised to be somewhat high for much of the day. Low-level flow wasn’t the strongest, either, but deep shear still fell within the margins of supercell and tornado days. Low-level forcing was subtle, but hourly surface streamline analyses revealed that confluence zone and its persistence. It wasn’t a classically straightforward setup at all. In fact, I had sent the following in a private note to a group of friends and associates before heading out: “Messy day–one of those that’s good for a needle-in-haystack ‘misoscale accident’…”. That’s exactly what happened.

The Two Chumps headed NW toward Watonga, encouraged not only by increasing juxtaposition of favorable parameters and foci in that area’s data fields, but also, good ol’ preconvective spotting with the human eyes that showed thicker convective towers in that part of the confluence zone.

In Watonga, numerous storm enthusiasts had accumulated to shoot the bull, empty the bladders and pass the time, with at least one (Conrad Ziegler) on a serious scientific mission. Conrad graciously invited us to a NSSL mobile lab vehicle to see data streaming in real-time from a freshly launched portable sounding. As we were discussing the weakening cap and other interpretive characteristics of the still-plotting RAOB, another use of the eyeball tool proved fruitful. Through the trees behind the Love’s fuel station, we caught a fair view of a very deep tower blowing the lid away to our NNW, near Fairview. Initiation!

Organizing to mature supercell stages

Rich and I cruised NNE to a suitable observation spot just S of Okeene, watching the towers deepen further, glaciate, and evolve into a bonafide cumulonimbus with some great anvil-aided crepusculars. As the storm started to anchor, grow and assume some visual supercell characteristics, we went E of Okeene, in its SE-moving path for a few minutes. We then embarked on a zigzagging trek with a net SE bearing, along well-maintained back roads, in and out of the sunlight, between Okeene, Loyal and Kingfisher. It was a tricky and difficult balance between getting in the storm’s shadow (better viewing contrast) and staying out of the intensifying forward-flank hail dump. In fact, at one point N of Loyal, we were getting subsevere hail in the sunshine!

While observing the twisting soda can of a storm, we were joined for a spell by BC, Ed C, Blufie and Joel Genung. Seldom has there ever assembled a more motley crew of grizzled, longtime, smart-ass chasers on an old dirt road. It reminded me of some friendly June convergences on the High Plains of Colorado, right down to the tan-colored wheat fields and high, roughly textured cloud base; but of course, the red dirt gives away the more southeasterly geography. We even could see the stacked-plate structure and shallow wall cloud of another supercell to the N, through the translucent core of the nearest storm.

Despite the insults and wisecracks dutifully exchanged, it was a pleasure to share several minutes of this young supercell’s lifespan with those guys…until the storm closed in and we had to disperse farther SE. We stopped a couple times between the Loyal area and Kingfisher as the storm expanded its base, produced more precip, and began to tighten up areas of enhanced cyclonic shear with occasional scuddy, slowly rotating lowerings.

Even though the ambient cloud base remained high, each lowering in a long series of them seemed to be a little better organized, condensing a little closer to the ground, thanks to some combination of lower pressure and higher RH, and a little more confidently rotating. This one, seen from S of Oneida, appeared as if it could tighten up to tornadic scale before being undercut by outflow. Nonetheless, that was one of my favorite views from the chase–again very Colorado-like under one of my favorite lighting conditions: looking NE into a high-based storm with little rear-flank precip, well-lit ground and darker forward-flank core area in the rear. That view seems to bring out some of the best texture and scuddy contrast in such storms.

Proceeding briskly southward on a dirt back-road, we were trying to reposition SW then S of the storm when a gustnado formed to our ESE, near the leading edge of the outflow from the nearer mesocyclone’s occlusion process. The resulting tube rose along the inflow-outflow interface and may have gotten involved with the updraft at cloud base (photo looking E, and contrast-enhanced version). If so (and that’s not certain), one could count it, though it was at best a fleeting and ephemeral “cheezenado”. I suppose we could claim it as tornadic if we were keeping score in some competitive tornado-fishing tournament. Fortunately storm observing isn’t like that, nor should it be.

We managed to get S of the storm for a short time as we found a viewing area on the SW edge of Kingfisher, watching an old occlusion to the N (manifest as a broad, outflow-undercut cyclonic shear zone) and a new one to the NE that rotated broadly but was still high-based. Under the latter, a scuddy, conical, slowly turning lowering briefly appeared above some dust–it would have been over the W side of town–but the dust appeared to be translating and not spinning. That’s good for Kingfisher.

Aware of the accumulating hordes of chasers and pseudo-chasers, we stayed off the main roads as much as possible in a SE-bearing zigzag between Kingfisher and Piedmont, remaining mostly S of the storm until reaching OK-3 (NW Highway) W of Piedmont. Meanwhile, reports of huge hail were starting to roll in–not surprising given the long-lived nature of this supercell and the environment it occupied. We had plenty of incentive to stay out of the hail core!

We stopped briefly on a dirt intersection near the Kingfisher/Canadian County line to watch a few short-lived areas of small-scale rotation in the newer mesocyclone, which itself had evolved into an elongated, cyclonic shear zone at cloud base with an ill-defined clear slot and some turquoise-toned precipitation areas. The episodic zones of cloud-base rotation were tighter and stronger than at any prior time in the storm’s lifespan, but still brief, shallow and apparently undercut. The storm acted like it wanted to produce a tornado, but needed some outside assistance.

Tornadic stage

It was during that maneuvering that we began to realize that a left-mover to our SSE was going to crash into the forward flank of our supercell, given their respective, extrapolated motion vectors. More importantly, the outer part of the left-mover’s rear-flank gust front (RFGF), which on radar reflectivity imagery arched NW and W out of its parent storm, eventually would smack into the mesocyclone region of the cyclonic supercell, somewhere not far SSE of us near Piedmont. We surmised that could be the outside assistance, and our best opportunity to see a legitimate spinup.

After all, think about the sign of the vorticity produced by the same relative part of a “normal” supercell’s RFGF: anticyclonic. It follows, therefore, that the same segment of the anticyclonic left-mover’s RFGF will contain enhanced cyclonic vorticity. Infuse any right-mover’s mesocyclone with more cyclonic vorticity along a boundary, and things could get very interesting for at least a few minutes, until the air behind the boundary gets too stable for the right-mover’s updraft to process efficiently.

Yes, we were nowcasting these processes, and charted a course down OK-3 to get just SE of the most likely interaction spot and witness it front-row, ringside. We also reprised an old quote of Rich’s from 1998: “Something out of this is gonna do whatever’s going to happen.” Even after conceptualizing how it could occur, we were amazed that it actually did!

In this shot, the mesocyclone area is seen to our NNW (the road goes NW). The center of the mesocyclone was translating generally SSE toward a spot just to our W. It didn’t look like anything imminently threatening–still with a rather high, ragged cloud base, and a much bigger dump of precip to its N and W than ever. The RFGF from the left-mover was passing our location with a wind shift, behind which we noticed only slight apparent cooling. We maintained position as the mesocyclone approached and the left-mover’s RFGF proceeded into it, saw a radar truck and some other chasers (including media trucks) bail SE past our watch at high speeds, and then…

Within the broader meso, a compact area of cloud-base rotation appeared with a small, tight fan of spinning dust beneath. Tornado! Here’s a wide-angle (full-factor 30 mm focal) within 10-15 seconds after tornadogenesis. Ground circulation was less than a mile to our NNW, time 2018 CDT (118Z), and we were located 3 N of Richland. It had no condensation funnel yet, and wouldn’t for several more minutes as the circulation churned S toward and across OK-3.

This wide-angle photograph shows the circulation with about its greatest dust production, before it rapidly wrapped in rain, crossed OK-3 with a power flash, and spun across wetter ground. The dust, scud above and cloud base were rotating in sync, as was the case when the cloud-base feature began to narrow after crossing the highway. I stood out in the wrapping rain as the weak tornado moved W through SSW of us, shooting wide-angles of the tornadic circulation at cloud base with what little dust it could raise, until 2024 CDT (124Z). At its closest point, the tornado was around half a mile away, with a few embedded subvortices–but never expansive enough to threaten us directly.

Of greater concern was the hail wrapping all the way around the meso–some of which started bouncing off the road around us and looking bigger than two inches. A few minutes before tornadogenesis, the supercell had dropped at least five-inch diameter hail N of Piedmont! Fortunately, none of the damaging hail hit the vehicle as we bailed SE on OK-3 then S on OK-4. We still were in transit (S on OK-4) during the short-lived, rain-wrapped condensation funnel, which Rich could see to our W from the passenger seat at about 2030 CDT (130Z). We actually didn’t get any photos during the condensation stage due to being mobile. By the time we found a safe pull-off, the tornado was gone.

Tuttle-Newcastle evening supercell

Storm mergers and outflow soon doomed the old mesocyclone area, and a major convective mess took over. In darkening twilight, we continued S on OK-4 past I-40, noticing a storm with a fairly large updraft area to our distant WSW and W. That storm assumed some supercellular characteristics, both visually and on radar, but we admittedly were surprised by unconfirmed media reports of a tornado in the Union City area.

We found a side road W of OK-4, a couple miles N of I-44, and began observing the supercell as it moved over Tuttle. Illuminated in various ways by lightning, town light and twilight, this storm was a beauty! I shot numerous photos as the storm approached, mid-upper level electricity brilliantly illuminating the scene aloft as its striated skirt swirled ever closer.

Hail markers on this storm seemed rather large, so we went to Newcastle (in its path) to find an overhang and observe the hail. By the time the storm reached there, however, it had grown upscale into a mess and merged with other cores, producing mostly heavy rain and small hailstones. Tired from a long chase day (and evening!), the Two Chumps then aborted intercept actions and turned E to Norman, satisfied that we milked this atmospheric regime for all it could offer–except the five-inch ice bombs, of course, which we chose to avoid.

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