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.

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.

A Run for the (Kansas) Border

April 11, 2009 by · Comments Off on A Run for the (Kansas) Border
Filed under: Summary 

Oklahoma Fires and Kansas Junk Storms
9 Apr 9

Ashton Cook, Jonathan Garner and I headed N from Norman at ~1300 CDT, eschewing a chainsaw-chase through the rugged terrain of Bigfoot-and-banjo country for a play at what appeared to be a textbook “cold-core” or “bent-back area” pattern along the frontal zone, just E of the surface low. I was concerned about the large dew point depressions along the boundary, but hoped that a narrow zone of transition between the well-mixed air and cold/moist air would do the trick for any discrete and rotating storms interacting therewith. After all, such a regime has produced short-lived, but often very photogenic, tornadoes in the past. The main missing ingredient in that sector of the system seemed to be a storm. So…off we went!

Things changed en route. A small area of high-based (midlevel) convection that had developed over the northeast TX panhandle and NW OK, and which I saw before leaving as beneficial evidence of strong large-scale ascent spreading into the region, turned the whole “bent-back” regime into a worthless convective turd pile. It kept growing and deepening into an expansive, thick shield of clouds, virga and occasional rain reaching the ground, based on mesonet reports. Whatever else was or wasn’t favorable, I’m increasingly convinced that this was what deep-sixed things. The big cloud/precip bomb didn’t just violate the textbook, it tore the “cold-core tornado” page right out and threw it into the wildfires. But we didn’t realize what was happening fully enough until we got up to near the KS line. Real-time RUC mesoanalyses of 0-3 km CAPE bore this out…namely, there was none. It’s hard to get good boundary layer cape under a huge pile of clouds and precip! So we tried to settle for the dryline storms, the first of which was a pyro-convective initiation — or at least, pyro-convectively aided in its early stages.

Along the way, near the SWO exit, we encountered a growing wildfire crawling toward I-35. The smoke already lofted into a growing clump of towering but very high-based cumuli along the dryline — convection that eventually would develop into the first PNC-Arkansas City storms. I stopped at a hilltop parking area to take a quick photo, then hurried back onto the interstate to get past the smoke plume before authorities inevitably closed the road. [Had we known how lame the storms would become, we might have just stuck around, saved another ~350 miles of driving, and done some fire photography instead.]

As we drove by, various stringers and pillars of flame consumed dry grass and assorted small brush, often within a stone’s throw of the freeway. One particularly impressive fireball erupted within a grove of small cedars around 100 yards W of the road. A few emergency vehicles already had begun to appear on the scene, but it was obvious they were too few and too futile to stop what was about to happen.

The dryline was moving over the fire(s) right at that moment, with gusts above 50 kt soon to follow. We knew the crawl soon would turn into a roar, pockets of flame destined to amalgamate into an outrageous conflagration gravely imperiling anything and everything in its way. The growth of that inferno was a topic of occasional conversation and speculation amongst us the rest of the chase. Naturally, we were not the least surprised to hear news reports, on the way home and long after the chase was over, that the fire had grown to 6 miles in length and I-35 still was closed.

By the time we got to ICT and turned E to Augusta, the “bent back” regime was a lost cause, and we tried to salvage the chase by shooting a gap and getting into the inflow sector of what had become a broken line of occasionally severe dryline storms to our near east. By the time we did, a few miles NW of Fredonia, the whole complex had devolved into a cold, outflow-dominant mess, within which we measured 51 deg F surface temps.

Back behind that activity, a lone storm formed SW of Fredonia in a lingering pocket of relatively unstable air, along the warm front. This storm rose upon an arching mesobeta scale boundary, evident in reflectivity presentations as a fine line, within what (by then) was the cold-core zone, and nearly collocated with the deep, eastward-moving surface low. It sported a broad updraft base beneath initially vigorous updraft towers. Occasional mild lowerings appeared, but the storm soon got undercut by some combination of its own outflow and the cold air from the earlier storms.

So we ate a quick dinner in Independence KS and headed back into the smoky Oklahoma night. The smoke plume from upstream fires not only darkened the reddened hue of the risen moon, but diffused the same light into the surrounding part of the eastern sky, as if painting a crimson corona.

On the way back through BVO/TUL/OKC, we admired the radar presentations of the supercells from SW AR down to the SHV area using Ashton’s phone feed, and encountered a few more terrestrial pyrotechnicals. A small (few acres) fire near Stroud cast its smoke plume aglow in orange N of I-44. Several miles down the road, we encountered a rather peculiar scene of small flames burning bark within the upper reaches of very widely scattered, individual trees on both sides of the interstate. A few emergency vehicles could be seen, but not much (if any) flames on the ground beneath those trees.

Notice I’ve written more about the fires than the storms. This is no accident. I hope for no more chases where that can be said!