Roundup from Roundup to Roundup
near Denton, Judith Gap and Roundup MT
19 Jun 13
SHORT: Fun chase day. Marginally supercellular to linear but scenic storms central MT, with day and night photography.
LONG:
Prologue and Pre-storm Fun
Central Montana had been in our sights for several days as a potential chase target–an ejecting Pacific shortwave trough, negatively tilted and fomenting reasonably strong deep shear, with backed low-level winds into the area of surface isallobaric response–but with the common northern High Plains problem of marginal moisture. Capping didn’t look to be a substantial problem. The strongest deep-layer ascent would be north of the Canadian border in SE AB or SW SK. However, for one, we didn’t have our passports…for two, storms up there would be racing northward and potentially messy, and third, the potential in the corridor between BIL and GTF didn’t look too bad. Low-level forcing looked rather nebulous and uncertain away from the higher terrain, so we decided to cling closely to potential orographic foci–the various ranges NW through SW of LWT, and the Little Snowy Range, a small mountain range sticking up out of the plains S of LWT that is a rarity in the Rocky Mountain region by virtue of being oriented E-W.
Storm observing in Montana is a different experience altogether. While they call this Big Sky Country for a reason, you need the great visibility because paved roads often are very widely spaced and oriented in ways not amenable to staying close to a storm. Small mountain ranges and pockets of forested hills poke out of the vast Plains like islands in the sea of prairie grass, presenting obstacles to both visibility and direct routing from one point to another. Deep river valleys with choppy terrain break up the otherwise decent-quality network of unpaved roads, which otherwise are pretty passable for those of us with high-clearance 4WD. In many areas, you’re 60-90 miles from the nearest services of any kind, and cellular phone coverage is often nonexistent away from major highways. The fuel tank must be topped off at every reasonable opportunity, and the vehicle kept in good working order with knowledge of how to handle minor mechanical breakdowns yourself.
Why chase in Montana? Intercept strategy there must be flexible and humble–two concepts often quite unfamiliar to Okie-style “storm chasers” who love to sniff the vapors and get the “XTREME INSANE” footage. Instead, storms up here are best appreciated from a distance, with occasional sampling up-close as they cross safe roads. That’s fine with me. The landscapes are vast, often breathtaking in their grandeur and late-spring beauty. As foreground settings for skyscapes, or on its own merit, Big Sky Country is a photographer’s delight. Finally, though it is being discovered, chase crowds are far less of a problem here than in the southern and central Plains. It is possible to get off by oneself on a storm and not see another vehicle for a long time.
Roundup is a friendly but rather dormant little town with a few (but just a few) lodging options. Its few restaurants and one grocery store close early, so if you arrive after 9 pm from a chase, you’ll have to eat gas-station food. Bring extra soap, too–the water is wretched: unclear, extremely hard and laden with sediment. We finally found a place on the Plains with nastier water than Odessa! Still, we started the 19th there after the previous day’s leisurely trip up through the Bighorn Basin and BIL. Little did we know that we would end the day there too, making a full circuit through and around LWT.
With storm initiation several hours off, we headed for LWT–a surprisingly picturesque and pleasant town smack in the center of MT, with the Little Snowies lining the nearby southern horizon. The lunch buffet at the Yogo Inn was outstanding–one of the best I’ve had anywhere up and down the Plains–with fast Wi-Fi to check the latest data. The town’s water supply is cold, clear spring water–absolutely outstanding in taste and quality, the very opposite of Roundup’s, and some of the best I’ve ever consumed. It’s one of the few times I’ve had nothing but water to drink with a meal, and loved it. The worst and best water I’ve had on any chase trips are less than 90 miles apart!
Towers gradually developed and deepened to the W as we were finishing up lunch, so we picked up a camera supply piece for Elke, did a brief driving tour of town, then headed N on US-191 to the Carters Ponds public fishing area on the Plains for an unimpeded view to the W. While visually monitoring the slowly evolving convective buildups to the W, we enjoyed the bird watching and photographing opportunities there, along with views of the low range of mountains to the E, and even did some fishing–didn’t catch anything, but it was fun anyway. We had a great pre-storm experience–definitely beats hours spent sitting around some Interstate truck stop!
Judith Gap/Snowy Range Supercells
Anvils began streaming off very distant convection back in the Absaroka Mountains SW of BIL, shrouding the convection to our W and making it harder to see. Still, the darkening of the closer area meant storms were building–an assessment confirmed by a brief window of online radar accessibility. We headed NW on MT-81 across the broad Judith River gorge to the Denton area to get closer, stopping at the abandoned Great Northern Railway car number 902 near Coffee Creek to photograph that and watch the convection to our W.
This was the farthest W and NW we ever have been on a chase trip–due N of eastern UT and eastern AZ! Elke was uneasy to be so far from home–the most distant yet by vehicle alone, a 3-day drive if any emergencies came up. Still, we kept vigilance. The storms took on a more strung-out, linear configuration, running parallel to their NNE-SSW axis of orientation, remaining rather fuzzy and featureless visually, and hugging the E edge of the mountains. This convection didn’t appear to have much of a future except as a quasi-linear mess.
Fortunately, additional storms were firing on the northern tip of the Bighorn Mountains near BIL and well SW of LWT, back near I-90. Plenty of daylight remained at this high latitude, so we reversed course and headed right back through LWT then WSW toward the Judith Gap, stopping along the way to photograph an abandoned farmstead. A supercell became apparent on radar S of Harlowtown, right on US-191 and moving N up the highway toward the W edge of the Little Snowies. We mapped out an intercept strategy to head down 191 and see the supercell before it hit the mountains, and in case the storm right-moved, jump onto what appeared to be a good unpaved road network S of the Little Snowies to watch the whole process.
Popping through the Judith Gap revealed an expanse of plains S of the Little Snowies that bristled with wind turbines–a fitting setting for the approach of a northward-moving supercell (looking SSE). Alas, the storm was being undercut by its own outflow and that of more convection upshear to its S, while moving N. We would have to either: 1) jump E into those unpaved roads to get out of the way of approaching cores with their probable hail and flash flooding, or 2) retreat back through the gap then E into LWT, awaiting whatever was left of the storm as it came over the mountains. We chose the former–but before doing so, managed to shoot a few daytime lightning photos from a high spot just S of the town of Judith Gap.
One captured a CG in the rear-flank core region behind a small wall cloud and RFD slot that soon became overwhelmed with outflow (looking WSW–again these storms were moving mainly N, so turn your conceptual perspective 90 degrees to the left). A few others were shot looking SW as that core passed, and another approached.
What was left of the inflow-notch region coiled back into the mountains to our W, while the base of another marginally organized supercell revealed itself behind still more core to our S. What fun! All this convection was training up a quasi-linear series, just as the earlier useless mush SE of Great Falls; however, this was offering more interesting processes and features.
Zigzagging E and S from Judith Gap to get out of the way, we stopped several times to observe what was left of the second supercell gust out spectacularly. As it did so, the storm veered NE into the Little Snowy Range in scenic fashion, the mountains forcing lift of cold, moist outflow air, the arcus and scud scraping the slopes as it rose. The hard-rightward deviance wasn’t because of convective propagation on the rear flank, but instead, the storm’s surfing its own outflow.
It’s a good thing we didn’t take the LWT option and wait on the other side of the mountains. The storm’s outflow barreled down the north slopes of the Little Snowies and smashed through LWT with significantly severe ferocity: measured 81-mph wind gusts that downed numerous trees in the town where we drank such delicious water several hours earlier.
Southern MT Storm Complex
The supercell having exterminated itself, we turned our attention and our path southward toward Shawmut and the paved US-12. In the distance, bases and cores were forming in several places to the S, SE and E, seemingly all at once, including what was left of the earlier Bighorns convection. Meanwhile, storms pulling off the mountains to our SW, behind the supercell, were growing in size and looking like linear outflow-makers. We were in an island of relative uneventfulness, but far from any paved roads for the inevitable closure of the storm gap SE of Judith Gap.
Before figuring out how to navigate that predicament, we stopped briefly to photograph an abandoned farmstead (main farmhouse and accessory outhouse), then jog SW a bit and view a picturesque, onrushing arcus roll from the trailing storms. While the scene back at the farmstead was a treat, we knew that a lot of storms were going to come together not far from us, and tangling with the resulting complex wasn’t going to be easy. Going E would just keep is on unpaved backroads a lot longer and delay the inevitable. If we headed S, we’d stay in a relative gap for awhile, with maybe some moderate precip, before being engulfed somewhere near the paved road where at least driving would be on firm footing. So it was…
For 20-something miles, we wound generally southward on pretty firm dirt and gravel back roads before reaching the crossroads of Shawmut, and paved US-12. Meanwhile the big wall of outflow that produced the roll cloud had surged out NE, E and SE, raising even more convection into storms–and those began unloading on us right as we reached the highway. The storms to our E also filled in.
With only this option back E, and the text day’s target area somewhere in western-central ND, we were resigned to plowing through (and with) a big blob of convection moving the same direction, all the way to wherever we felt like stopping for the night. We found large branches across the highway in the Ryegate/Lavina area, and PINGed that, while hearing reports of hail and damaging wind in locales ahead of us along the highway. I slowed down in order not to penetrate the worst of the wall of wind and woe.
Right about at Roundup, twilight started deepening, so we decided to stop there for the night. Hailstones littered the ground — some over an inch in diameter, along with broken small limbs; and golf-ball-sized hail had been reported there earlier. Exactly one room was available in town, about 70% below ground level, so we grabbed it and hoped against flooding. The room was actually decent quality–better than we had the night before.
Upon seeing a great, post-sunset mammatus display outside our room window (which was up the wall, at ground level), I wanted to head outside of town to shoot the sky. Elke was very tired, and stayed back. By the time I found a good vantage on a dirt road a few miles NE of town, the mammatus display had smoothed some and moved off quickly in step with what now was a raging, quasi-linear MCS blasting away toward Jordan and Glasgow. Still, in the fast-fading twilight, a blend of in-cloud and distant cloud-ground lightning peppered the eastern and northern sky, as the trailing mid-upper clouds streamed off to the NE. Here is a short animation looking NE that includes the latter shot, and another short time lapse looking E.
This was a long and nontornadic chase day–but nonetheless, very interesting, rewarding and memorable 12-hour circuit around central MT! We slept very well that night, and needed the rest to prepare us for an unexpectedly big drive into southern ND and northern SD the following day.
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Our PING trail for this day.