Squall Line Way Up North
St. John ND
10 Jun 12
SHORT: Blew off chasing in trees in MN or driving from ND-KS in one shot, intending to hang out in ND ’til the pattern returned favorable parameters to Dakotas. While en route to Int’l Peace Garden, intercepted photogenic, low-topped squall line and attendant arcus cloud over very green fields near St. John ND.
LONG:
The cold front from the previous day’s action was slated to shift into more forested land of central and northern Minnesota, within which we didn’t wish to chase. Strong to severe storms also were possible farther south, along and ahead of the front, in mode viewing-friendly areas of Iowa, NW Missouri and Kansas, but under weaker deep-layer shear.
Laundry beckoned, and so did a few days of R&R in the heretofore superficially explored state of North Dakota before the next substantial atmospheric perturbation brought severe potential to the northern Great Plains. After finishing the wash and brunch in Grafton, we charted a net WNW course on the township-range zigzag of eastern and northern North Dakota, aiming to grab a couple bucketfuls of rich, black soil from the old Lake Agassiz bed for my vegetable garden back home (check), visit Icelandic State Park (uncheck), see the Pembina Gorge (check), visit the International Peace Garden (check), and spend a night or two in the so-called Turtle Mountains (check).
Somewhat retracing the route we took the evening before, we encountered a fantastic layer of asperatus (a.k.a. “warm-advection clouds”) between Grafton and Cavalier. That was followed immediately by a rather featureless, messy band of elevated thunderstorms that timed badly for visiting the state park. Instead, we headed up to Walhalla and toured the misty, scuddy and decidedly green Pembina River Gorge by car.
Ascending that small canyon, which drains an escarpment separating the Plains from the Red River of the North valley, leads the driver to the marvelously open, flat and attractive countryside characteristic of most of the state NE of the Missouri River. Folks here seem to inherit their ancestors’ fastidious tidiness ethic. In towns, this means well-kept houses, gardens and lawns. In rural areas, we saw a distinct absence of junk cars, rusty appliances, neglected fencing, or haphazard accumulations of dilapidated mechanical rubbish strewn across weedy lawns of occupied homes–in other words, a refreshign difference from thousands of points of blight that are prevalent in the southern Plains countryside. Landscapes here were familiar from the day before, but the setting was different–scuddy, light rain on the back side of the elevated storm band, with broken blue sky to the west, and the cool, moist freshness of wet earth behind a summertime cold front. This trip already was a splendid pleasure, and soon would become more so.
Proceeding westward across the borderlands, we finally broke into sunshine west of Langdon–but not for long! Onboard radar showed a thin, curving arc of cold-core thunderstorms developing to the W, over the turtle Mountains. A low-topped squall line was forming–something that experience told me could be quite photogenic in such otherwise clean air and sky. It was.
Approaching the squall line from the SE (as it moved quickly eastward), we marveled at how shallow and low-topped the convection was–typical for a cold-core low in a low-CAPE, relatively low-tropopause setting–but still rather uncommon in my southern-latitude experiences. In fact, just a few miles ahead of the arcus cloud, sunshine still illuminated the moist and richly verdant fields adjoining the east side of the Turtle Mountains. This clearly was not any of the 60,000-foot-deep walls of deep-convective severity I’m accustomed to observing in a North Texas April.
Our viewpoint was just SE of St. John, only four miles S of Canada, and in a fine position to view the oncoming shelf cloud. We were able to frame the sweeping arcus above the gentle curve of a rural dirt road that nicely split the greenery. After that, we cruised into St. John and let the storms move over us, enduring a decent barrage of small hail and subsevere gusts.
Heading into the hills, we quickly left behind the weakening squall line and visited the International Peace Garden (highly recommended, no passport needed!). The storms had run off the visitors, so we nearly had the place all to ourselves in rain-cooled air with sunny, late-afternoon light. Afterward, and with no one behind us in the customs line, I had a long, very friendly conversation with a customs officer and USAF vet at the re-entry station (the park is directly astride the border, its driveway halfway between U.S. and Canadian customs). He gave us a good recommendation for lodging options beside beautiful Lake Metigoshe–at which we reserved two nights for R&R before the next chase-worthy, northern-Plains shortwave.
Storm Observing Drama in Four Acts
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.
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.