Spring 2011 Grand Finale: A Tornado-fest

September 9, 2011 by · Comments Off on Spring 2011 Grand Finale: A Tornado-fest
Filed under: Summary 

NW KS to south-central NEb
20 June 11

SHORT: Food, fishing, baby-bird rescue and a bunch of tornadoes…on final chase day of the vacation and season for us, with three tornadic supercells in northern KS and southern NEb.

LONG: Awakening to a windy, moist, scuddy morning in Alma, NEb, beneath a rip-roaring ENEly low-level jet, Elke and I knew this could be a productive storm day, but had no idea that it would land in the top few of our entire storm-observing careers. Indeed, if you include the calendar day–having witnessed the second of two spectacular, lightning-illuminated supercells after the stroke of midnight (story here), there is no question that his goes down as an all-time top-5-class chase day for either of us.

Pre-storm

After looking at morning charts, I targeted two plays:
1. Mid-day tornado potential in the “bent back” region of the occluding surface frontal zone, W of the dryline and near the surface low. Even by mid-morning, this regime was taking shape in west-central KS and moving directly N toward us, with only some diurnal heating and a storm needed to engage intercept mode.
2. Late-afternoon potential on the nose of the dry punch, near the dryline/warm-frontal triple point, over east-central or SE NEb. This is the regime I had in mind for a couple of days, but forecast backing of flow with height in the midlevels (a harbinger of linear storm modes) had me concerned.

Obviously, given where we were, #1 was a no-brainer as first choice, despite my historically lame fortune with “cold core” supercell regimes. If that option either busted or died out early enough in the afternoon, the rather slow eastward component of the deep-layer cyclone’s motion meant we could blast east, preferably on a road suited to it like I-80, and intercept the dryline storms.

With that strategic concept in mind, and a lack of food options in Alma, we headed for HDE to eat late breakfast/early lunch, then to a nearby city park to bide some time reading (Elke) and fishing (me) before storms went up.

I didn’t get too many casts into the lake because of a sad sight I found underneath a tree: two dead baby robins, blown out of their nests by one of last night’s supercells, and one still alive and shivering with hypothermia. After some deliberation about what to do, we noticed other robins and nests up the tree. Elke, who has a longstanding soft spot for baby birds, warmed the featherless little critter while I shimmied up the tree in search of a suitable nest in which to place the orphan. We got it in a snug nest (albeit alongside a much larger and older baby), hoping its new sibling could keep it warm and the new mama would feed it. Chances are it didn’t survive; but we tried.

First tornadic phase: “Long Island/Stamford” supercell

During the avian-rescue experience, a storm had formed (early, as cold-core storms often do) and quickly had become supercellular near HLC. By the time I got a good radar read on it, the storm already was tornado-warned. Though it was moving our way, we still were in HDE, well to its NNE, so…back S through Alma we went, and across the KS line. Mike U already had seen his festival of tornadoes by the time we caught the storm S of Long Island KS, but it was far from done.

Terrain in the area was somewhat choppy and frustrating to navigate, so we settled for the first decent hilltop view we could get, 3 S of Long Island. The supercell was moving toward the N and NNE at various times, with dark murk inside, a tall precip cascade on its SE (rear-flank) edge, and clear, blue sky to its E (our SE). Surface winds blew from the ENE to NE, as they would throughout the duration of our engagement with this supercell. We and the storm were a little leftward of the track of the surface low!

In the murk–and curiously, in the forward-flank interface region ahead of the main mesocyclone, we saw a small, tightly rotating wall cloud emerge, with a pencil-shaped tornado dangling beneath (photo: as seen and super-enhanced versions).

The tornado lasted about three minutes and dissipated, before a different, seemingly shallow, front-flank mesocirculation started spinning like mad to our W. That planted a dusty multivortex, which also was low-contrast (photo: as seen and super-enhanced versions). Whoa! I had based our intercept positioning, relative to the supercell, on the likely track of the primary mesocyclone, which stuck out eastward from the SE side of the north-moving storm.

By now, I had figured out what was going on, but that didn’t make it any less surreal. Pearls of enhanced rotation were forming and spawning front-flank tornadoes, along a necklace of very rich vorticity characterizing the inflow-outflow interface. A conceptual model of the situation looks something like this 2-D cartoon. Why this supercell was going nuts with front-flank mesocirculations, whilst most others don’t, is a question I’ll leave to the numerical modelers for the time being. In the real world of a storm intercept, this presented a strategic quandary, in that getting closer to the front-flank tornadic necklace also meant getting in the path of a rain-wrapped HP mesocyclone of a fairly fast-moving supercell.

As the second tornado churned northward, in step with storm translation, another suspicious feature caught our attention (Elke actually saw it first). A wide view of the storm (photo: as seen) shows the precip-wrapped, main mesocyclone to the left, and at far right, the dusty multivortex. Right before taking that shot, we spotted a dark, smooth, persistent, and reasonably wide lowering in another area of front-flank rotation, buried somewhat back into a precip-filled notch. That made ground contact, with rapid rotation of cloud material above and around the tapered-barrel shaped tornado. We had two ongoing, plus one that likely was underway in the main mesocyclone but not yet visible. More on that beast later. As for the two we knew, the arrows point to the visible tornadoes in this super-enhanced/zoomed version of the last shot.

We had a peculiar situation at hand.

After a few minutes, we lost sight of the southern front-flank tornado as it buried itself in precip, while the leading one narrowed and proceeded toward the N. We headed N too, crossing the KS/NEb state line about the same time as the leading tornado to our W (photo: as seen and super-enhanced versions).

Once that dissipated, we still had an original, dominant mesocyclone to our SSW, in which we couldn’t see anything thanks to persistent, rotating moat of heavy precip that cloaked the mysterious tempests of danger lurking within. This situation was getting weirder all the time, and was about to become truly bizarre.

I drove through Orleans and a few miles NW on US-136, which angled us closer to the front flank and somewhat in the path of the big meso. Lo and behold, just ahead of the rain-wrapped main meso, a tall, skinny, dusty tornado came into view to our WSW (photo: as seen and super-enhanced versions). This definitely was separate from the previous tornado, and probably just S of the KS/NEb state line. Meanwhile, a new and relatively robust shear-zone updraft to our NW (separate from the dissipated dusty tornado #2) started spinning frantically, and beneath a shallow, bowl-shaped and rapidly rotating lowering, spun up another short-lived, dusty tornado (photo: as seen and super-enhanced versions)! After the latter tornado dissipated, the prior, dusty tube seemed to spin down gradually instead of roping out, as if it simply lost its will to rotate.

Whither the main meso? At long last, we started seeing the answer as a rapidly rotating, nearly ground-to-anvil column of rain and hail churned toward us. Something very menacing, dangerous and unsavory began to appear from within the whirling dungeon of heavy precip–a big fat tornado (photo: as seen and super-enhanced versions). Look behind and above the tree row. I think what we’re seeing here is not just the rain-wrapped low levels of the tornado (dark wedge below cloud base, with helical scud coiling about).

Also, note the convective column containing the tornadic circulation (and not much larger in width than the visible tornado down low!) bending above and to the right. This is NWward with height on a N-moving storm, looking SW. [Conceptually, turn your usual NE-tilt on an E-moving storm leftward 90 deg as in the 2-D cartoon ]. In essence, you’re seeing the tornado-cyclone from ground into the mid-upper levels of the storm, visually. Yes, it was convective-looking, but corkscrewing pretty fast visually. Alas, even the mid-upper part didn’t shed its cloak of rotating rain curtains for very long; mostly it had been a bear’s cage from ground almost to anvil, for much of this storm’s lifespan in my view. I’m glad the curtains parted just long enough to reveal this fascinating deep-layer structure–and of course the hefty hose beneath.

My question: Was this the continuation of the Mr. Umscheid’s wedge from way down by HLC, or a separate tornado? Some shots by Walker Ashley seem to indicate a smaller barrel====>cone tornado earlier in this meso’s lifespan, and farther SW in KS. If so, either
1. Walker;s tornado expanded again to a rain-wrapped wedge shown here, or
2. This was a new one.

Whatever the case, the main-meso tornado likely had been ongoing for a long time, given that we had observed tremendously rotating rain curtains around the area for many minutes. This clearly was a very large, well-formed and mature tornadic vortex by the time we finally could see it. The entire tilted cloud column was rotating rapidly.

Wrapping precip again obscured the tornado within two minutes, or about the time it crossed into Nebraska. Orbiting rain curtains continued around the mesocyclone for several miles N toward Stamford an perhaps beyond, until the entire supercell evaporated from below and died W of HDE.

I read reports of “skipping” tornado paths with this storm in this area, which is bogus on two fronts:

    1. By definition, a tornado cannot “skip”. If it’s not on the ground, it’s not a tornado.

    2. Semantics aside, there simply was no “skipping”. The various different tornadoes in this area near the border, lined up similarly, probably gave the illusion of “skipping” of damage.

After the initial storm died, we got fuel in HDE and then couldn’t flank the downshear Elm Creek storm. We knew it was tornadic based on spotter reports and the SRM signature, but it was planted squarely on the highway to our N, near I-80. The first storm had put us out of position to see the business end of the Elm Creek supercell, so we jumped on the Interstate with its 75 mph speed limit and pressed the pedal hard in an eastward run for the second target area.

Second tornadic phase: “Hampton and Bradshaw/Stromsburg” supercells

Visually, a series of deep, glaciating towers to our ENE-E-SE looked reachable and was growing. By the time we passed the HSI/GRI exit, an unbroken wall of dense cores loomed to the E on radar, their convective towers lit by a blend of direct and filtered sunlight. My hope was that, despite the linear mode, a “tail-end Charlie” would roll up toward I-80 after I could penetrate the line and get into the inflow air. Linear storms don’t tend to hurl gorilla hail; so I was at ease with cruising up to the back and shooting through a relative gap.

That’s exactly what we did, except that the southern part of the line was breaking up into more discrete (and disturbingly, rotating) cells right as we started the penetration. We took a pounding from marginally severe hail, gazing southward through precip to see if anything could show up in the nearest area of rotation S of the Interstate. As we cleared precip and a ragged base came into view adjacent to the core, Elke saw a brief needle funnel 4/5 of the way to the ground. That might have been a tornado; though flooded fields precluded appreciable dust generation. No debris was visible beneath.

As we neared the Hampton exit, another core loomed to the SSE, moving N. We continued to press E, getting pounded by still more hail. Clearly the line had broken up into closely-packed supercells and we needed to get out of their way! A few minutes after we cleared the N side of the intensifying precip area, I glanced behind us to see a barrel-shaped, rain-wrapped tornado in the S part of the same core, about to cross the Interstate (photo: as seen and super-enhanced versions). That was a little too close for comfort, though we really had about 5 minutes’ cushion. I pulled off the road, jumped out, and gestured wildly at some westbound traffic not to go that way. Fortunately, they slowed down and pulled aside.

What appeared to be a big, low-visibility and significant tornado (as it turned out to be!) was almost upon the Interstate (photo: as seen and super-enhanced versions), and I was hoping nobody would drive into it. Enough precip wrapped around the tornado that we couldn’t see it with our eyeballs as it crossed I-80 (photo: as seen and super-enhanced versions), though it narrowed somewhat to a stilted stovepipe and became more visible again between I-80 and US-34 (photo: as seen and super-enhanced versions).

The Hampton tornado appeared to hook NNW and move away from us. Our last view of it (photo: as seen and super-enhanced versions) came with a troubling realization: we still were getting peppered with precip, including increasingly large hail! The real tail-end Charlie still hadn’t reached I-80 yet; and indeed, another core was moving overhead with a low base diffusely visible to our SSE. Time to high-tail it east again! As we pondered getting off the Interstate at the Bradshaw exit, Elke looked out and up to see rapid cloud-base rotation nearly overhead, atop that very exit. We kept going!

Behind and slightly leftward of us, the tornado first appeared in the rear-view mirror while driving out from under the meso. A small dust plume spun up just N of I-80. Above that loomed a rotating cone funnel that extended about 1/3 down from cloud base. We zipped a mile or so E, then pulled safely off the road to watch. This tornado was highly visible and quite photogenic, a marvelously sheathed column into which the condensation funnel seemed to poke, spike-like. “Finally,” I thought, “all these tornadoes today and we have a high-contrast specimen!” I said something more coarse, but fortunately, cannot recall precisely what.

Without an immediately available north road, we watched for a few minutes as the tube widened and retreated northward away from us, a wide-angle view revealing more of the tail-end supercell’s swirly updraft structure. Although rather distant, we had the tornado in view all the way through JYR and up US-81 to a point 4 ESE of Polk, where we pulled over briefly to watch it rope out to the WNW. This was our longest continuous view of any of the day’s tornadoes: 18 minutes.

A new lowered base even farther N told me this storm wasn’t through with cyclic tornado production yet. As it was moving N rather quickly, slightly ahead of abeam to port side, the town of Stromsburg and its inevitable slowdown dead ahead, we had to get moving for any hope of seeing the next hose. A few miles S of Stromsburg, we saw the newest and last tornado of our day emerge from the haze, to our NW.

Of course, traffic slowed to a crawl in town, a chain of cars inching N at about half the posted 25 mph speed limit, some slowing down or turning indecisively as if thoroughly bewildered. Townsfolk stood in at least half the yards gazing in various skyward directions, not sheltered, despite the ominous wail of storm sirens. I thought, “They’re safe and don’t realize it yet; but if the tornado were headed into town, we would have multiple casualties amongst all these unprepared and confused citizens”. What I actually said might have been a tad less civilized, so it’s good that I can’t recall that.

By the time we got extricated from Stromsburg and headed N for a few miles, contrast improved enough to pull W half a mile and get a few decent shots, including this one looking NW across a corn field at the stout, grinding vortex. Motion of the ragged cloud base around the top of the visible tornado was impressively speedy. Driving a few more miles N on US-81, we finally got roughly abeam of the tornado again, only to see it rapidly narrow and then rope out.

Just in case the storm would cycle once more, we headed up an unmarked road off the east bend of US-81, in the general direction of Duncan. Alas, the supercell quickly displayed a rain-wrapped, outflow-dominant structure, and would produce no more tornadoes. We turned around to head back to JYR, photograph a couple of elevated cells (looking E and looking N from the S side of JYR), grab a room, and get some celebratory steak dinner before restaurants began to close.

Epilogue

A hearty meal was in order too. During a long storm-intercept day, we successfully had observed at least 8 and perhaps up to 10 tornadoes, from three different supercells, in two separate forecast targets and meteorological regimes. All I can say is, wow…only 3 May 1999 clearly exceeds this for my one-day tornado total. We don’t chase just to see tornadoes–far from it, actually–but you bet we’re appreciative of them for their rarity, uniqueness and power–the dichotomously ironic “Beauty of Atmospheric Violence” that is the title for my storm-photography shows. Best of all, nobody was injured through all the whirling mayhem of the day.

It was an amazing grand finale to an unprecedentedly bountiful 2011 Great Plains severe-storm vacation (and season)!

I had called in several of the tornadoes as soon as safety and cell signals would allow, a few while they still were underway. Within a couple weeks after we returned, I processed the day’s images (before all others from this vacation) and sent an itemized table of tornado times and estimated locations to the affected WFOs, with embedded links to many of the same photos as above. That table includes times, locations and links to the above photos. The tornado log file is in the public domain, and linked here in MS Excel format, freely accessible for anyone interested.

Beautiful Outflow, Day 3: Along a Familiar Trace

August 21, 2011 by · Comments Off on Beautiful Outflow, Day 3: Along a Familiar Trace
Filed under: Summary 

Limon to Sheridan Lake CO (again!)
18 June 11

SHORT: Observed high-based, outflow-dominant supercell with “cheezenado” near Kit Carson CO and deeply textured spectacle of structure. Pretty sunset near ITR.

LONG: This was the third straight day of outstanding outflow in the American Outback. We started the day in LAA, with a stop at Bent’s Fort along the way to our target area, which remained the LIC-PUB corridor as supposed the previous night. While the Fort was fun to visit and photograph again, we slept in too long, got there later than hoped (midday), and stayed long enough to miss the initiation and early stages of a supercell near LIC.

Roaring N out of Rocky Ford, we caught up to the thrice tornado-warned storm just S of LIC (it was, fortunately, rather slow moving up to that point). Despite its fine appearance on radar reflectivity for over an hour prior, early visuals suggested nothing even close to tornadic: a high based storm with a rather small, tilted updraft and opaque to translucent core. The temperature in that RFD was 56 deg F, not exactly priming the pump for tornado action given the lofty LCL of the storm.

We took a little bit of mainly sub-severe hail, from the trailing (rear-flank) precip area while turning around to jog S and E toward Hugo. A major core-dump just N of Hugo (as seen looking NE from just W of town) sent the storm on a southeastward, outflow-surfing odyssey that seemed quite familiar. Already, the irony wasn’t lost: the storm of interest was in the same general area, also high-based and apparently outflow-dominant, and headed roughly the same direction, as the supercell the afternoon before. Indeed, we would retrace much of the previous day’s familiar path.

One difference this day was that the storm legitimately threatened to produce something tornadic on two occasions–both when my phone’s signal-bar area was stamped “No Service.” [Thanks again, AT&T with your disingenuous “97% of the population” advertising.]

We pulled off US-287 near Wild Horse and drove a few miles up a dirt road for a better view, only to see that the terrain constantly was higher between us and the storm. As we got closer, a lowering I had seen for a few minutes in the distance became visible as a persistent, smooth, bowl-shaped (and sometimes fat-cone shaped) protuberance embedded in translucent rain. It was rotating–not very fast, but noticeably. As I got out to take this wide-angle shot, the lowering’s bottom became more rounded and higher, and it went away within a minute. I was imagining what a supercell like this could do with less outflow, lower cloud base and more inflow-layer moisture.

Meanwhile the already-nice structure just kept getting more and more textured and beautiful (looking NW from near Kit Carson). The sharply defined, undular raggedness of the bottom of each cloud-base terrace gave me the impression of looking upward from beneath at a boiling liquid surface.

::::: Begin meteorological interpretation :::::
In a way, though the causative processes are much different, the convective principle is quite similar, when you consider the “liquid surface” analogy as a reverse counterpart of the CCL or LCL. In boiling water, the liqud turns to vapor. At the cloud’s LCL or CCL, the vapor condenses to droplets. Amidst a very broadly intense updraft, little bitty parcels neighboring each other are reaching their condensation pressure fast, but at slightly different elevations, giving the underside of the cloud mass such a rough, sandpaper-like appearance. The difference in condensation level from any one of the “mini-parcels” to another probably is related to a combination of slight variations of pressure, temperature and/or humidity in each one, before and during its ascent. This contrasts with the laminar (smooth) bases we often see in supercells, where the vertical pressure-gradient force compels a sheet of air to rise along a gently sloping path (along an isentrope) to a less locally-variable LCL, then ultimately to its higher LFC, where now unshackled from CINH, it really goes ballistic and rockets upward at speeds even faster than CAPE alone can support. In this specimen, LCL and LFC were either roughly the same level, or LFC was lower (free convection occurring before saturation).
::::: End meteorological interpretation :::::

Back to the chase… This stunning view (17 mm wide-angle), looking W from 6 W of Cheyenne Wells back toward Kit Carson, compelled us to stop for a spell, knowing that the forward-flank core would move overhead and force a southward turn of our own soon. Little did I know that this most unlikely-looking of high-based High Plains storms was about to produce a tornado.

See the precip-filled occlusion slot in the lower middle of the last photo? A few minutes later, as I was gawking and babbling with semi-coherent admiration at the sky-filling structure, I heard Elke yell, “I think there’s a tornado in there!”

Me: “In where? No way!”

Elke: “Right there!”

Me: “Right where?”

Elke: “In there!”

Me: “In WHERE???”

Elke: “In the rain! Behind the updraft!”

Me (fumbling with camera gear): “Come on, from that storm? There ain’t no…hmm, wait a minute. Holy $%#^, that is a funnel in there. Get on there, stupid zoom lens. Dust! I think it might be a tornado!”

As usual, she was right. At least this time, she didn’t have a road atlas with which to hit me. 🙂

It was short-lived (~3 minutes), a long, slim, very stretchy condensation tube that began to break up even as I finally got the zoom lens attached and snapped the photo. The enhanced crop shows some of the dust it had spun up from the dry fields beneath. Other observers who were closer to the cheezenado’s location (SE of Kit Carson) also pegged it on a couple of SpotterNetwork icons, as I saw later once regaining data coverage. It was a flimsy excuse for one, but still, WFO GLD’s first tornado of the season. [The reports on the day’s rough log actually were of that one event, seen/reported from different places.]

As we dropped S out of the Wells, the brief spin-up soon became almost a forgotten sidebar in the face of one of the most fantastic and bizarre visual appearances I’ve seen from any storm. At that point, other cells were merging into its back side, with an initially separate storm base visible in the more distant W.

The supercell quickly was evolving into a small forward-propagating MCS, ralphing even more outflow. The resultant, bigger storm cluster formed a pretty, tiered shelf on its E edge (looking NE). Back to the WNW of us, an outflow-undercut but visibly rotating convective column briefly formed and poked into the ambient cloud base, adding more morphological weirdness to the whole event. The earlier “rear” storm, visible in the last shot, also was growing bigger, getting closer and becoming outflow-driven.

Pulling into the same Sheridan Lake petrol station where we had been the day before, I fueled up and spoke with some familiar faces behind the counter. “We’re back, and we brought another storm with us!”

I also chatted with Chris Weiss of TTU, whose Sticknet teams I had seen deploying their wares along US-385 as part of some sort of outflow-measuring experiment. [They had arrived at the storm right after the cheezenado and didn’t know about it.] That bunch should have acquired a great dataset; for the gust front soon barged through town unabated and well ahead of the main core, which itself turned left and barely missed to our E.

A few minutes later, a very concentrated and suspicious-looking, but non-rotating, dust bomb rose to the SE. Plow wind! The dust plume fanned out, advected away and eventually dispersed, as we turned back N for the 63-mile drive to ITR and a favorite motel there.

Along the way, several elevated and very high-based storms formed atop the cold pool from the earlier complex, including this one just S of ITR. South of town, we enjoyed a splendid sunset sky while parked in between wet plowed fields, and while talking to Rich T on the phone. He had seen his first tornado of the year that day–400 miles to our SE, along the OK/KS line W of BVO. We were glad for that too, as his chase fortunes this year had been awful so far.

After three days of beautiful outflow, we were ready for some meaty supercell action as portended by richer moisture and stronger shear forecast for the next day.

Second Dose of Beautiful Outflow Dominance

August 20, 2011 by · Comments Off on Second Dose of Beautiful Outflow Dominance
Filed under: Summary 

Limon to Sheridan Lake and Lamar CO
17 June 11

SHORT: Intercepted two supercells that quickly became outflow-dominant in east-central CO. Picturesque structure. Nighttime lighting, mammatus and moonrise show near Lamar CO.

LONG: Starting at the laundromat in Yuma, we headed S at midday toward a forecast initiation area near the Palmer Divide, which by the time we hot the open plains S of town, already bubbled with tall convective towers. As in the previous day, I was concerned that storms would go too soon and create a big outflow surge; but instead they percolated for some time, struggling to organize as we approached LIC. There, we sat under the NE edge of a high-based, fuzzy, virga-spraying line of cells, none particularly impressive for about an hour.

Finally, as so often happens on these highest of the High Plains, a few distinct updraft bases materialized from the mush, one of more of which I guessed would evolve into a supercell, given both the favorable deep-layer shear and increasing low-level moisture content with time. When some of the virga started to reach ground as rain in LIC, we zipped several miles S of town then W a mile on a dead-end dirt road to watch the action unfold, while remaining in at least marginal phone-data coverage of LIC’s cellular towers. Turns out we didn’t need the data…as often is true out there, the eyes have it.

Two supercells developed essentially in sync — one to our somewhat distant W beyond Simla, the other to our NW between Matheson and LIC.

The closer storm evolved fast, and in fascinating ways. The initially broad, high updraft base in the last photo lowered somewhat, with a broad, ragged cigar of scud materializing beneath as the updraft began to process rain-cooled air from the neighboring parts of the forward-flank core. Notice, in the last photo, the lower-middle part of the scud bank seems to be rising off the ground. In fact, it not only was rising, but weakly rotating–before the broader scud stogie ever attached to the parent storm’s cloud base: a “scudnado” indeed! The scud mass kept growing and rising, becoming part of the storm’s updraft base and lowering it tremendously. This is a classic example of a storm modifying its own thermodynamic environment to ratchet down its own LCL!

Meanwhile, we saw intermittent chunks of ground-based scud, rising and slowly rotating. Nothing appeared too threatening from the standpoint of developing a real tornado, but it certainly kept my attention, in case the circulation ever started to tighten up to ominous levels. Some of them certainly had that look (zoom lens and enhanced digital zoom). I was pleasantly surprised and glad to see that nobody called these in as tornadoes, knowing that a lot of chasers were roaming about the area (based on Spotter Network icons). Another example a few moments later: (zoom lens and enhanced digital zoom).

The first supercell moved ENE over the LIC to our N, and gusted out. That turned our attention to the second (western or “Simla”) storm, which had sported intermittent, mostly non-rotating and ragged lowerings so far. A large, weakly rotating and precip-wrapping wall cloud developed as the storm drew closer, thanks to a a big mass of rain-cooled air entrained into the main updraft region. The supercell turned hard right, heading ESE and bearing the forward-flank core on course for the location where we comfortably had parked for about an hour. Time to head S again…

N of Punkin Center, we stopped to the updraft’s E again, this time for a short spell to photograph some beautiful clean-air storm structure. The supercell grew ever more outflow-dominant by the minute and accelerated its forward speed, so we couldn’t stay long. One more shot of the striking form of the storm, a marvelously textured swirl of gray shades and turquoise looming across the western sky, and it was time to bail over toward Aroya to open up some room between the storm and us. Along the way, its gust front briefly passed to the NE and to the N.

Approaching Aroya, we remembered a beautiful, old, abandoned schoolhouse we had seen on another chase nine years ago, having wished someday to photograph it before an approaching storm. This was our chance! The result is one of my favorite Great Plains scenery shots of the year so far.

Near Wild Horse, the supercell tried hard to enlarge a surface-based updraft, and appeared to succeed. The result was another spectacular display of texture and shading. Yes, that lowering at the inflow-outflow interface was rotating–slowly, but helically, giving me some concern for a brief tornadic spin-up. This one (zoom, and enhanced zoom of a zoom) compelled me to call, but thanks to being in one of the many tens of thousands of square miles of the Plains that constitutes AT&T’s 3% of America not served, I had no signal.

Fortunately, that feature quickly dissolved under relentless assault from cold outflow. Shortly after those shots, YF Umscheid motored up the dirt road toward us from a vantage closer to the feature, without reporting anything of consequence. We stayed ahead of the storm as it surfed outflow, driving E to Cheyenne Wells then S to Sheridan Lake. Between those burgs, we stopped to photograph the increasingly high, tiered, arcus-like eastern part of the base and a pretty array of sunset tones on the W side.

The storm now being a windbag and dust-bomb, we left it to get some lodging in LAA, setting us up for a long-desired revisit of Bent’s Fort and perhaps another chase opportunity the next afternoon off high terrain near and S of the Palmer. We found a nice, locally operated motel, then headed just SW of town to watch a short-lived, probably elevated supercell approach in the fading twilight. Elke was getting tired, so we went back to the motel, as the storm peppered town with abundant hail up to 1 inch in diameter (definitely smaller than the supposed “golfball hail” in the local storm reports).

A good lightning show beneath and on the back edge of the storm sent me back S of town again onto a different side road, this time to photograph the mammatus-festooned electrical show from the rear. As crickets and frogs sung loudly from every point of the compass, that amazing moist-earth smell refreshing my spirits amidst cool outflow air, the lace-lightning display continued with the storm’s eastward retreat. As a bonus wonderment, to cap a fine storm day, an orange moon rose beneath and then behind the distant updraft base. In the last shot, above the flanking line, you can see the anvil edge illuminated by the moonlight, in addition to the lighting by lightning within the storm.

After a long and satisfying chase day, we slept very soundly that night!

For your enjoyment, and as a reward for patiently reading this far, I’ve thrown together a couple of coarse animations from tripodded still-camera images shot that night: the first of the retreating storm with lace lightning, and the second of the wide-angle moonrise scene.

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