Pawnee Grassland Supercell and Sterling Sunset
Filed under: Summary
Cheyenne WY to Sterling CO
15 Jun 13
SHORT: Chronically photogenic storm from CYS to Sterling.
LONG:
We began the day in Ft. Morgan with increasing (but still marginal) low-level moisture feeding two forecast plays:
- The dependable Cheyenne Ridge/Laramie Range region, which seldom fails to pop a storm under upslope flow and substantial surface heating, and
- Palmer Ridge/Front Range area farther S, similarly dependable but under weaker flow aloft.
My privately posted chase forecast discussion read, in part…
“This pattern strongly resembles several that have fired grand supercells off the LAR mtns NW CYS — some with spectacular tubes — though moisture today is a little less than I’d like to see it for tornadic action. Postfrontal winds should turn around after 18Z and go upslope into that area. If a storm can fire over there, it could proceed ESE through the extreme SE part of WY and eventually in an oblique path across the NE CO border…”
That was the scenario we selected; and fortunately, that’s exactly how it worked out. Such success doesn’t happen as often as I’d like, so we should celebrate when it does. On this day, we celebrated with some splendid stormscapes and one of the best Great Plains photography days of the year.
First, however, we ate a great buffet lunch at a highly-reviewed place in eastern Ft. Morgan, away from all the main highways: the Country Steakout. Try them next time you’re in the area, especially if you want to get really full, before a chase. We then trekked through the Pawnee National Grassland on the way to the CYS initiation target. [We would return through this amazing area later in step with the supercell.] Along the way, we found an abandoned farmhouse that showed us decent photo opportunities even at midday (samples: outer wall texture, another outer wall scene, light and shadow through a window and on the floor, more exterior boards).
After that, a lone Cb arose off the WNW horizon, which satellite imagery confirmed was firing off the southern part of the Laramie Range, just as hoped and predicted. We headed through CYS, passing Mike U and a few other chasers along WY-211 (Horse Creek Rd) to find an excellent vantage for the approaching storm, which offered a large and textured but ragged and elongated updraft base.
Peeling itself off the highest terrain and heading ESE, the storm kept that elongated-updraft look after crossing the Colorado border near Hereford. Although this storm flirted with excessive downdraft production and outflow-dominance on several occasions, it was able to maintain just enough proximal inflow to keep from gusting out–remaining photogenic all the while. A view to the E, from the same spot as the last shot, showed multiple, parallel, cumuliform inflow bands feeding into the high base. What an interesting and beautiful process to behold!
Road voids over the buttes and mesas (here spotlit with sunlight against a dark storm background) kept us somewhat distant from the storm at times, and/or relegated to its SW side, but that was obviously not a problem from a photographic standpoint. In fact, we stayed on the western fringes of both the storm’s rear-flank core area and the Cedar Creek wind farm to take advantages of (and marvel at) scenes like this and like this.
Back roads delivered us healthy and well to CO-71, whereupon we headed S to CO-14, stopping along the way to view the gorgeous towers to our NE over the shortgrass prairie. Eastward we moved on 14 to get back near the SE-moving, high-based supercell, which seemed to be accelerating. Daylight fading, we decided to stay in good light and on the storm’s back side as it approached Sterling, and let the rear-flank gust front and its wondrous collection of tinted cloud material pass over the green wheat fields.
Sunset time was a dazzling experience, with elevated storms that were growing to the W helping to cast differential light, shadow and hue across the convective sky to our immediate SE. I had to slap on a multi-stop graduated neutral density filter to offset some of the dynamic range (old-fashioned, I know…but it worked out well). At times, the colors were out of this world…seldom have we witnessed such a variety of light and texture in such a small part of a convective sky! The experience was amazing–parked on a remote, dirt back road with nothing but us, the sky, the cool breeze, and some singing meadowlarks for company. This is why we travel to the High Plains every year.
The convection to the W grew larger and started putting on a fairly furious electrical show after dark, but we had to forgo lightning photography to get Elke some suddenly-needed medicine in Sterling. That wasn’t available, so we headed promptly down I-76 to to the outskirts of DEN for the night, enjoying the flickering light show in our side windows and rear-view mirror while hoping she would be healthy enough to chase the following few days (great news…she was, and we had a fantastic chase in the Nebraska Sandhills the next day!).
Well in the Wells
Cheyenne Wells to Akron, CO
14 Jun 13
SHORT: High-based, outflow-dominant storms.
LONG:
Starting our annual Great Plains vacation the day before, we drove from OUN-ITR–a long haul. Morning this day found us in our favorite Burlington motel, the Chaparral Inn, realizing fully well that moisture was scant with the strongest deep shear located N of a slow-moving to stationary front over NE CO and NW KS. In short, it looked like a day when early towers might yield spouts, then it would be an outflow fest afterward. Hey, when dealing with the atmosphere, you can’t take more than you’re given.
First, however, there was some unfinished business to attend at the increasingly derelict “See Six States” tower, antique shop and very outdated tourist attraction near Genoa. The place, despite its schtick, is packed with history! Elke had spied a particular old bottle there last year that she regretted not buying; and sure enough it still was there, sitting on the same spot of the same shelf. The eccentric old man that ran the place, Jerry Chubbuck, was more than happy to sell it to her; he saw maybe one or three vehicles a day stop in, while thousands passed by on the nearby Interstate. [Sadly, Jerry died in August. What will become of that old place and its thousands of antique items?] I also had a little compositional photography in mind there (with permission) of some old bottles and the inside of the tower area upstairs. As we left, in early afternoon, convective towers began to build along the front to our ENE-SE-SSW.
Gradually and in stepwise fashion, we headed back E on I-70 then S out of ITR toward Cheyenne Wells, driving beneath the now high-based line of showers and storms. We never saw any spouts (updrafts were fuzzy, not firm, thanks to meager CAPE), but we did see a weak gustnado to the SE. In Cheyenne Wells, we had a great late lunch/early dinner at a small storefront cafe staffed and patronized by very hospitable people. My red-blooded, patriotic t-shirts, and the sociopolitical slant behind them, go over well in the Wells and in other small towns all over the Great Plains.
Several miles W of town, we stopped to observe and photograph an interestingly chaotic sky, before proceeding N toward lodging that would put us in position for the next day’s target area near the CO/NEb border. Also, on our way through the rain (coming into Cheyenne Wells), in town, after we headed E out of town, and in a second round of (heavier) storms near Anton, we PINGed the rain too. The green dots show our PING trails; we were the only PINGers in eastern CO for those storms. Finally, near AKO, we stopped to photograph the late-afternoon light with a background of dark clouds from the small Anton MCS.
It was a stress-free way to get into the swing of the trip. We had low expectations meteorologically, so this was a casually pleasant day of storm and landscape observing, food consumption, and visiting the old man’s fading attraction near Genoa, and for what may have been the final of several visits over the years to the See Six States tower.
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.