Second Dose of Beautiful Outflow Dominance
Filed under: Summary
Limon to Sheridan Lake and Lamar CO
17 June 11
SHORT: Intercepted two supercells that quickly became outflow-dominant in east-central CO. Picturesque structure. Nighttime lighting, mammatus and moonrise show near Lamar CO.
LONG: Starting at the laundromat in Yuma, we headed S at midday toward a forecast initiation area near the Palmer Divide, which by the time we hot the open plains S of town, already bubbled with tall convective towers. As in the previous day, I was concerned that storms would go too soon and create a big outflow surge; but instead they percolated for some time, struggling to organize as we approached LIC. There, we sat under the NE edge of a high-based, fuzzy, virga-spraying line of cells, none particularly impressive for about an hour.
Finally, as so often happens on these highest of the High Plains, a few distinct updraft bases materialized from the mush, one of more of which I guessed would evolve into a supercell, given both the favorable deep-layer shear and increasing low-level moisture content with time. When some of the virga started to reach ground as rain in LIC, we zipped several miles S of town then W a mile on a dead-end dirt road to watch the action unfold, while remaining in at least marginal phone-data coverage of LIC’s cellular towers. Turns out we didn’t need the data…as often is true out there, the eyes have it.
Two supercells developed essentially in sync — one to our somewhat distant W beyond Simla, the other to our NW between Matheson and LIC.
The closer storm evolved fast, and in fascinating ways. The initially broad, high updraft base in the last photo lowered somewhat, with a broad, ragged cigar of scud materializing beneath as the updraft began to process rain-cooled air from the neighboring parts of the forward-flank core. Notice, in the last photo, the lower-middle part of the scud bank seems to be rising off the ground. In fact, it not only was rising, but weakly rotating–before the broader scud stogie ever attached to the parent storm’s cloud base: a “scudnado” indeed! The scud mass kept growing and rising, becoming part of the storm’s updraft base and lowering it tremendously. This is a classic example of a storm modifying its own thermodynamic environment to ratchet down its own LCL!
Meanwhile, we saw intermittent chunks of ground-based scud, rising and slowly rotating. Nothing appeared too threatening from the standpoint of developing a real tornado, but it certainly kept my attention, in case the circulation ever started to tighten up to ominous levels. Some of them certainly had that look (zoom lens and enhanced digital zoom). I was pleasantly surprised and glad to see that nobody called these in as tornadoes, knowing that a lot of chasers were roaming about the area (based on Spotter Network icons). Another example a few moments later: (zoom lens and enhanced digital zoom).
The first supercell moved ENE over the LIC to our N, and gusted out. That turned our attention to the second (western or “Simla”) storm, which had sported intermittent, mostly non-rotating and ragged lowerings so far. A large, weakly rotating and precip-wrapping wall cloud developed as the storm drew closer, thanks to a a big mass of rain-cooled air entrained into the main updraft region. The supercell turned hard right, heading ESE and bearing the forward-flank core on course for the location where we comfortably had parked for about an hour. Time to head S again…
N of Punkin Center, we stopped to the updraft’s E again, this time for a short spell to photograph some beautiful clean-air storm structure. The supercell grew ever more outflow-dominant by the minute and accelerated its forward speed, so we couldn’t stay long. One more shot of the striking form of the storm, a marvelously textured swirl of gray shades and turquoise looming across the western sky, and it was time to bail over toward Aroya to open up some room between the storm and us. Along the way, its gust front briefly passed to the NE and to the N.
Approaching Aroya, we remembered a beautiful, old, abandoned schoolhouse we had seen on another chase nine years ago, having wished someday to photograph it before an approaching storm. This was our chance! The result is one of my favorite Great Plains scenery shots of the year so far.
Near Wild Horse, the supercell tried hard to enlarge a surface-based updraft, and appeared to succeed. The result was another spectacular display of texture and shading. Yes, that lowering at the inflow-outflow interface was rotating–slowly, but helically, giving me some concern for a brief tornadic spin-up. This one (zoom, and enhanced zoom of a zoom) compelled me to call, but thanks to being in one of the many tens of thousands of square miles of the Plains that constitutes AT&T’s 3% of America not served, I had no signal.
Fortunately, that feature quickly dissolved under relentless assault from cold outflow. Shortly after those shots, YF Umscheid motored up the dirt road toward us from a vantage closer to the feature, without reporting anything of consequence. We stayed ahead of the storm as it surfed outflow, driving E to Cheyenne Wells then S to Sheridan Lake. Between those burgs, we stopped to photograph the increasingly high, tiered, arcus-like eastern part of the base and a pretty array of sunset tones on the W side.
The storm now being a windbag and dust-bomb, we left it to get some lodging in LAA, setting us up for a long-desired revisit of Bent’s Fort and perhaps another chase opportunity the next afternoon off high terrain near and S of the Palmer. We found a nice, locally operated motel, then headed just SW of town to watch a short-lived, probably elevated supercell approach in the fading twilight. Elke was getting tired, so we went back to the motel, as the storm peppered town with abundant hail up to 1 inch in diameter (definitely smaller than the supposed “golfball hail” in the local storm reports).
A good lightning show beneath and on the back edge of the storm sent me back S of town again onto a different side road, this time to photograph the mammatus-festooned electrical show from the rear. As crickets and frogs sung loudly from every point of the compass, that amazing moist-earth smell refreshing my spirits amidst cool outflow air, the lace-lightning display continued with the storm’s eastward retreat. As a bonus wonderment, to cap a fine storm day, an orange moon rose beneath and then behind the distant updraft base. In the last shot, above the flanking line, you can see the anvil edge illuminated by the moonlight, in addition to the lighting by lightning within the storm.
After a long and satisfying chase day, we slept very soundly that night!
For your enjoyment, and as a reward for patiently reading this far, I’ve thrown together a couple of coarse animations from tripodded still-camera images shot that night: the first of the retreating storm with lace lightning, and the second of the wide-angle moonrise scene.
Beauty of Outflow Dominance
Nebraska Panhandle Bow Echo and NE Colorado Dry Downburst
16 June 11
SHORT: Fun day. Began in Hot Springs SD. Observed/photographed spectacular outflow-cloud structures (shelves, bands, stripes) with raging bow echo/haboob from BFF to N of SNY. Dropped S for peculiar, photogenic dust storm and sustained damaging gusts beneath high-based N rim of eastern CO MCS.
LONG: Back onto our storm-observing trek after a couple of amazing days in the Black Hills, flow aloft and at least marginal low-level moisture were beginning to juxtapose favorably once again to our south. We targeted the nearby Nebraska Panhandle for the prospect of high-based storms rolling east out of the higher terrain of eastern Wyoming. Browsing the morning maps, I was confident in upslope flow into that orography, along with afternoon storm initiation…but would there be too much, too soon, before the richer moisture could arrive in the evening? This scenario would mean outflow dominance.
Still, a conditional triple-point play in south-central KS was much too far away; and the mountains ain’t going anywhere. Blow increasingly moist air into them for enough time during daytime heating, and storms will form. Our goal: be downshear and see what evolves. High dew-point depressions portend shelf clouds, dust and high wind from storms; and sometimes that can be beautiful too.
And so it was…
We drove to favorite overlook SW of Angora upon which we had perched a few days before, watching the top 4/5 of assorted towers build and glaciate over the unseen mountains of eastern WY. Finally, when the storms started to coalesce and move off, one of which looked like an embedded supercell on radar, we headed W to the N edge of BFF to watch them roll downhill right at us. By then, the supercell was hard to distinguish in the onrushing wall of a dark, ominous, and increasingly well-defined squall line.
Reflectivity animations confirmed that the northern segment — basically due W of us, was bowing out. It was time to go outflow surfin’! Stay ahead of these, and they can offer some absolutely stunning cloud structures, such as the following three-piece view from between BFF and Minatare:
Looking NW: I’ve never seen a combination of lightness, darkness and radiating cirriform streamers like this before!
Looking W: Right into the teeth of Jaws. This is what a bonafide bow echo looks like when it’s “a-comin’ ta gitcha”. Check out the peculiar translucent strands, reminiscent of Silly String, festooning the otherwise featureless midlevel cloud deck. It might seem hard to photograph the strong dynamic range between the ink-dark core and the otherworldly apron of light above and beyond the shelf cloud; but not this time. This is how it actually looked, with no HDR bracketing necessary! I just had to meter for the area smack in the middle.
Looking SW: A classic view of an onrushing convective windstorm on the High Plains, this time with the Wildcat Hills lining the southwestern horizon.
We stayed ahead of the snapping maw of this storm — barely at time, I must admit — all the way to Bridgeport and beyond — before bailing S to let the road-deprived Sandhills have their turn at it. We got one last nice view of the atmospheric earth-mover raging to our NW before turning equatorward. What a gorgeous display of outflow-driven stormscapes we had witnessed!
Now it was time to get out of the way and figure out what to do with several more hours of daylight. Some storms had fired in NE CO, likely to be just as outflow-dominant and perhaps quite high-based. From SNY, it wasn’t that far away, and the next two days looked like potential Colorado storm targets anyway. As such, went back through Sterling again (retracing a good deal of our chase path from BFF three days before).
Unlike then, the Centennial State sky greeted us with a giant field of decaying storm material — virga dropping from various patches of agitation beneath a widespread anvil shield that once contained actual updrafts. N of Otis, a wall of wind slammed us in an impressive dry downburst, tearing dense channels of dust from plowed fields, buffeting the vehicle laterally with shot after shot of very localized wind-force lasting a second or so apiece, and making me struggle with the wheels to maintain positioning on the road. Good thing I had new tires for this season…
After a late rainbow and dinner at a familiar restaurant in Yuma, we bunked down there for the night, satisfied that we made the most out of a very windy storm day.
The human element of storm observing always has some interesting twists and turns too. We had a few loud neighbors at our motel, getting drunk and cussing in Spanish, and after a spell, I thought I might have to go out there and shut them up by request or otherwise. Fortunately for everybody, the former worked. The ringleader turned out to be cut from the cloth of my old barrio associates from long ago: he was wearing a shirt that said, in Spanish, “Don’t f___ with the DALLAS COWBOYS”. All day, I already had on my trusty blue-star cap. After some conversation about America’s Team, they retreated to their rooms, an elevated storm blew by with an intermittent show of close CGs, then off to bed everybody went.