Pleasant Diagonal across North Dakota

August 19, 2012 by · Comments Off on Pleasant Diagonal across North Dakota
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Rolla and Grafton ND areas
9 Jun 12

SHORT: Small convective towers and beautiful sunset Cb photographed along with abandoned structures and Northern Plains landscape.

LONG: This date loomed several days in advance, even in national forecast outlooks, as not just a potential supercell day, but tornado-outbreak day, across the eastern Dakotas. As time got closer, it became more and more apparent that the wind fields would be there–albeit in a smaller area mostly encompassing eastern North Dakota–but lack of robust moisture would be a major hindrance to storm development. So would capping, for much of the day, despite strong large-scale and frontogenetic forcing.

Elke and I had an additional logistic quandary in that the best low-level shear would be N of the Canadian border. We wouldn’t mind chasing there; but we didn’t bring our passports. So we undertook a strategy that, in essence, was: get ahead of the cold front and tuck ourselves just S of the border to jump on any storms that might develop to our S and mature before crossing the 49th parallel.

I was rather surprised to see the number of Southern Plains storm observers via SpotterNetwork attempting the long and dangerously sleep-deprived overnight trek from Oklahoma, Kansas and even Texas, for what looked to me like an ever more feeble setup for tornadoes. By contrast, we already were in the region and on vacation, with no particular place to be for a few days after the system departed. In fact, we fully intended to stay in ND after this day, until the next northern-stream weatehr system, and explore the state. North Dakota seldom was visited by us before now, and never in-depth, as true appreciation warrants. We had wanted to spend more than a couple of days in ND for many years, and now was the start of that chance!

Originating our trek from Bowman, in the SW corner of ND, involved an earlier-than-usual arousal from bed and crisscrossing the state on a diagonal. Fortunately, ND is not a particularly massive block of land (similar in area to Oklahoma), and the roads are plentiful and in good condition E and N of the Missouri River. Some short-range, convection-resolving models unzipped the front N-S across the eastern third of the state by about 4-5 p.m.; but I didn’t buy it. A simple examination of the 700- and 500-mb charts, surface chart and moisture-channel imagery indicated the strongest lift might not even occur before dark; and supercell initiation would be improbable before 0Z. For once, I was confident early development would not be a problem and storms would hold off before late afternoon, enabling a stop in BIS for lunch and procurement of a much-needed ND road atlas. [Yes, we still navigate chases exclusively with paper road atlases, though we found the BIS Barnes & Noble with I-Phone Google Maps–the best of both worlds!]

We zigzagged NNE from BIS through Rugby, stopping to visit the geographic center of North America. While heading E to stay ahead of the bent-back portion of the cold front, we crossed an outflow boundary from a strong morning MCS that was, in effect, acting as a warm front. Clouds on the NE side of the boundary were scuddy and more stratified than on the warm (SW) side that overtook us several minutes later. As the boundary crossed our location, we noticed that blades in the eastern portion of a nearby wind farm still were facing SE on the cool side, whereas those in the western part had pivoted to face S–a modern manifestation of “reading the wind”. Although those towers near the boundary were unlikely to build into a mature supercell before reaching the border, we had hopes others could fire farther S on the front and move our way.

Meanwhile, we stopped a few times between Rugby and Rolla to pass the time–enjoying the scenery of the Northern Plains‘ post-glacial landscape (closer shot of gaillardias with bumblebees) and that bit of Americana involving an old barn with glacial rocks. As seen from a spot near Rolla, as far N as we ever had been on a chase, convective towers kept bubbling along and ahead of the front to our W, but neither broadening nor deepening appreciably until crossing into Canada. Even then, they didn’t survive long upon crossing the remains of the outflow boundary.

Regarding the day as an increasingly probable bustola for sustained storms, but still wishing to stay ahead of the front, we headed several more miles E into Towner County. It was nearly 8 p.m., still plenty of (low) daylight left, and a few towers were erupting to our distant SE. Those appeared to be along the remnants of the outflow boundary, and a quick glance at a surface map confirmed that. But they also were on a sharply defined confluence line and the E edge of strengthening N-S baroclinic gradient ahead of where I thought the forward segment of the front should be by pure extrapolation of translation. The front was redeveloping (frontogenesis) ahead of its previous position–in effect, jumping E of us!

Zooming E on US-281 and ND-5, we realized that the first cell was moving fast and would pass our longitude before we safely could get there; it became a short-lived supercell just into Manitoba, N of the dying old outflow boundary. When realizing the futility of that pursuit, we stopped to photograph an abandoned farmhouse and barn in the warm, late-day light, with other frontal towers across the background skyline.

More cells fired to our SSE, this time reachable. However, since it would be just a little before sunset by the time we would intercept them along the now eastward-accelerating front, we chose to hold back W a little and photograph them from the side preferentially aglow. By the time we reached a point near Hoople (between Cavalier and Grafton), scuddy low clouds broke enough to afford us great viewing of the spectacle. As the sun set in the NW, a small cumulonimbus just past the Minnesota border reflected brilliantly in the eastern sky, turning deeper shades of peach and apricot before falling into shadow and growing dim. The convection softened, weakened and moved away rapidly after sunset, which was quite late in those parts (9:52 p.m. at our filming location); so we headed to nearby Grafton for lodging and a late fast-food dinner.

Elke and I had started the previous day in Cheyenne, WY, and ended it here in northeastern ND. That’s a long haul! Yet we had undertaken a scenic and rewarding trip, bisecting the central and northern Plains from SW-NE. The journey hadn’t been quite as tiresome as the many miles might make it seem, probably thanks to the many stops and small rewards bountifully scattered along the way. Still, we were ready for a few days of post-frontal rest and relaxation before the next storm-spawning system. I didn’t count on a fortuitous encounter with photogenic cold-core storms the next day…

Wyoming to North Dakota via a Nebraska/South Dakota Dryline

August 5, 2012 by · Comments Off on Wyoming to North Dakota via a Nebraska/South Dakota Dryline
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Cheyenne WY to Bowman ND
8 Jun 12

SHORT: Observed dryline towers, sometimes with smoke, near the NE-SD-WY state-line junction. Nice sunset over the SW corner of ND.

LONG:
Three main target areas presented themselves to us as we pulled out of CYS on a sunny morning:

    1. The closest but probably lamest: a high-based, deeply-mixed prospect for short-lvied, late-afternoon convection along the dryline, near the S rim of the Black Hills;
    2. A middle play along the NW rim of a narrow plume of relatively righ boundary-layer moisture, collcated witha confluence belt, in the SE MT/NW SD/SW ND area. This had been apparent for a few days–distant but reachable, given the likelihood of a stout cap holding off storm potential until late afternoon.
    3. More certain risk for a photogenic supercell or two in central MT, more removed from the richer moisture but in favorable deep-layer wind profiles. his was barely reachable with some long, hard driving and only brief stops, followed by a short night’s sleep and another day of long, hard driving to get all the way over to NE ND. That’s hardly the recipe to be able to stop occasionally and get out to appreciate the Great Plains!

Given the low likelihood of tremendous tornado action in the middle of Montana, we nixed option 3 early and decided to make a conditional play on the first two. We would head NNE to the CDR-CUT area for the dryline, then if it looked unpromising by around 21Z, be ready to zoom up through RAP toward 2WX where at least one high-resolution model (HRRRRRRRRRRRRRRRR) forecast a distinct supercell to develop.

Lunch in Lusk was good–Deacon’s Restaurant is one we can recommend! Appetites satiated, we took a back road–sometimes paved, sometimes not–to Van Tassell, stopping here and there to appreciate geologic formations as well as photograph abandoned structures from up close, in the middle and back a little.

The whole way from Torrington to Van Tassel, we kept an eye on the high-based cumuli accumulating in a persistent area of lift that passed overhead, then shifted E to the Nebraska border in step with the mixing-driven movement of the dryline. This photograph depicts the deepening convection from near Van Tassell WY, gazing ESE toward the dryline. A horizontally narrow but vertically thick ribbon of smoke from the Cow Camp fire in Wyoming (the inferno whose pyro-convection started the Wheatland supercell the day before) also was streaming steadily northeastward toward us, several thousand feet above ground level.

Van Tassell in the review mirror, we headed through Fort Robinson on the Nebraska side, passed through the dryline near Harrison, gathered some rocks on the escarpment E of Harrison, stopped briefly for supplies in Chadron, then headed NW toward the South Dakota border and one skiny but persistently deep tower. When we got to it, the tower obviously was suffering from dry entrainment, but presented a peculiar picture of light and shadow, as seen from underneath the ribbon of smoke and very near the state line.

Unconvinced of its future, we proceeded N beneath the ENE-moving tower’s base, encountering a few raindrops. A small Cb actually did develop briefly as we passed just to its N, and weak reflectivity appeared with it as seen from RAP radar. Still, given the degree of entrainment, and the presence of a few more hours of daylight, we headed up past RAP, Spearfish and Belle Fourche toward 2WX. We were worried that a traffic jam, in an I-90 roadwork zone NW of RAP, would make us miss any storms that formed to our NNW; that turned out to be a moot concern.

We waited for a spell in 2WX, calling Bowman to reserve a room, the threw in the towel on any model-phantom storm formation nearby and headed N to our lodging. Along the way, we stopped on a hilltop just N of the Dakota divider for a photogenic Northern Plains sunset. OF Crowther’s supercell is the Montana storm silhouetted on the horizon, about 190 miles away. Ain’t it amazing to be able to see that far?

Even though the chase day didn’t amount to a whole lot convectively, we enjoyed each other’s company, had a few unusual and welcomed photo opportunities, and positioned ourselves to get a good night’s sleep before the diagonal crossing of North Dakota the following day. In Bowman, we even saw a long, bright, overhead flyover of the International Space Station before turning in.

Storm Observing Drama in Four Acts

July 28, 2012 by · 2 Comments
Filed under: Summary 

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.

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