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.
High Plains Lightning Festival
Colorado-Nebraska Border Region
13 June 11
SHORT: Began in BFF. Waited in SNY. Avoided outflow-surfing CO/NEb border storms to intercept supercell near AKO, saw probably non-tornadic dust whirls with storm merger there. Fantastic twilight lightning display from elevated storms along border S of IBM.
LONG:
Elke and I started the day in BFF, targeting the general area of the CO/NEb border SE of there. I wasn’t particularly jazzed by the weak lower-tropospheric winds in the forecast, figuring outflow and/or storm splits would be a problem. Still, it’s the high plains in early June with adequate moisture, upslope flow and at least marginal shear. The answer? Be there.
We waited a good, long time at a hilltop outside SNY, just NW of a dryline that eventually would fire up a tornadic HP supercell in the horrible road network and terrain of the Sandhills. We saw those towers to the distant NE, but chose not to pursue given the great difficulties involved with storm intercepts in those parts.
Meanwhile, we listened to meadowlarks and, on radar displays, watched chaser icons on SpotterNetwork zigzag back and forth across the area in impatience as the lack of focused action. Fuzzy storms began to fire between the Laramie Range and Cheyenne Ridge, which was no surprise; their distant bases were so high we could see them from SNY. I wasn’t impressed. Red dots converged on I-80 and headed W. We sat, waiting and hoping instead for dryline development to access richer moisture to our SE and E.
Finally, off to the distant SW, two storms erupted near and N of the Palmer Divide in Colorado. This was near the very southern fringes of our forecast area; but as nothing much was happening with the dryline nearby, and the storms were reachable, we decided to go have a look. Along the way SW, through the convoluted maze of roads that is Sterling CO, the southeast storm attracted quite a few chaser icons. The NW storm didn’t, was closer, and was in a similar environment; so we headed toward AKO to intercept it.
Alas, along the way, the SE storm calved off a big left-mover and died! Moreover, the left mover shot toward the inflow region of our target storm like a torpedo hell-bent on mutually assured destruction of both storms. Briefly, we got a view of the NW supercell’s mesocyclone area to our WSW before the left-mover’s core arrived; and it looked like a somewhat higher-based version of a North Texas HP “Stormzilla”. This meant big hail; so it was imperative to get S fast.
Yet there loomed the left-mover over the road to our S, likely bearing ice bombs also. It got there as we did, just S of AKO. The two storms started to merge overhead, and in the tiny gap between their cores, two strongly rotating dust whirls appeared less than a mile to our W, about 3 minutes apart. [I was driving and driving hard, so...no photos!]
Though a narrow, ribbon-shaped updraft had formed overhead at the merger location, we could see no obvious rotation in it. I attributed the whirls to gustnado-like vortices being stretched where the two gust fronts met. We maintained an equatorward bearing, encountering only marginal severe hail at best (to our relief).
Arriving just S of the combined storms, which indeed were killing each other, we photographed the dying supercell across rain-drenched corn stubble S of AKO. It was good to see Steve Hodanish and to swap Hodo stories with a co-worker of his, and also, to talk with a few other friendly storm observers whom I hadn’t met before. Yet we were essentially stormless, parting ways and headed back toward our various bases for the night. All that was left, for now, was outflow spinning a windmill under a dark and stormy high plains skyscape.
We headed toward lodging in the Nebraska Panhandle, soaking in the sights of Pawnee National Grasslands in anticipation of spending a couple of upcoming non-chase days of roaming around some of our favorite haunts around the Black Hills, not counting on any more atmospheric excitement. As good fortune sometimes plays on previously under-performing storm days, the night brought about an unexpected–and most welcome–show of splendor that made our night!
A short line of elevated and high-based thunderstorms erupted over the WY-NEb border region atop the outflow pool from all the late-afternoon activity, and moved SE across the southwestern Panhandle and across the Cheyenne Ridge. Evening storms like this in the High Plains can spark profusely, and these absolutely did! We found a vantage just over the CO/NEb border S of IBM (Kimball, not the company) and began shooting away at the approaching spectacle. Assorted forked and in-cloud displays slashed across the fading twilight, their reports blasting resonantly across the wide-open landscape. Soon, some cloud-to-air discharges flickered forth, followed by yet more (and closer) sky-splitting CG action. Wow…what a show!
The lightning was getting too close, though; so we drove through the translucent core of the thunderstorm line a short distance into IBM, crossing a few miles of small hail (with almost no rain!) along the way. I’ll never forget the sight of countless thousands of little white hail balls in the high beams–cascading dots of brightness, the only form of light shining back at me along that dark High Plains highway.
After securing a motel room near the edge of town (like we like to do), we noticed the sparkling display still underway to our SE, and headed back out past the E edge of town for a little crawler-lightning show in the trailing precip region. And with a few more flashes to light up the midnight hour across the western Nebraska prairie, bedtime drew nigh, our storm-hungry palates duly satiated. I had very few lightning photos to show for 2011 until this night, when the heavens unloaded electrical gifts one after another in a most dazzling and appreciated fashion.
Chugwater Tornadic Supercell
Chugwater WY, 20 Jun 10
SHORT: Observed tornado from second of two supercells E of Chugwater.
LONG: Since Scotts Bluff National Monument was just a few blocks from our motel doorstep, we had time for some late morning through midday hiking, as well as photographing wildflowers and other interesting scenery near the top, before grabbing a quick lunch and heading west to our target area of southeast WY. See, for us, the so-called “storm chase” vacation isn’t just about storms, but about appreciation of as much of the Great plains’ offerings of beauty and wonder, large and small, as possible — storms being the major component, but not the entire experience. And so it was that we strolled atop the bluff o’ tuff, pondering the view up this way from the Oregon Trail’s wagon trains rolling up the North Platte valley below, while also occasionally looking at surface maps and satellite images on our I-Phones, and considering the effect the stable air represented by this stratified overcast would have on the day’s convective potential.
Thin breaks and occasional peeks at the sun indicated some destabilization was occurring, in an area of nicely backed surface winds from there westward, and automated mesoanalyses of CAPE and CINH fields bore that hunch out. As we descended from the hill, as if on cue, the first towers began to erupt over the Laramie Range, where the clouds had been eroded over the highest terrain in the area, allowing maximum heating. We couldn’t see them through the stratus, of course, and I had doubts about how far E convection could make it off the mountains before getting into grunge and weakening There was no doubt we needed to follow Horace Greeley’s old advice and “go west”. As we did so, two storms started to rotate:
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1. A cell in the Wheatland/Dwyer area, headed NE toward Jay Em but also toward some decidedly stable air, and
2. A storm moving somewhat more slowly and seemingly anchored along the foothills near Chugwater.
We went through Torrington along the way, then SW, catching a brief view of the distant and uninspiring base of the northern storm, before moving SW toward an area of obvious darkness above and beyond the intervening stratus deck. By the time we got to a good vantage W of Yoder and S of veteran WY, the southern storm, which had been a supercell, already was losing definition in its base and soon would turn into a strung-out, most likely elevated plume of convection.
Fortunately, the strong heating continued off the W edge of the stratus deck and the E edge of the mountains, firing additional convection still farther SW. With the boundary layer continuing to get more unstable in that direction, we backed through Yoder and S again past Hawk Springs. Then we then headed up the beautiful bluffs E of Chugwater along one of my favorite drives in the region (WY-313), only to greet an already well-developed and obviously surface-based storm by the time we arose on the high plateau E of I-25. The storm was calving off left splits, one of which can be seen beyond an abandoned farm structure in this shot looking WNW. Turning our attention to the WSW, the large, robust right mover quickly cut a clear slot and formed a broad, rotating, bowl-shaped lowering
behind it (and above the letter “s” ending my name in this wide-angle shot). This was only a few minutes after we had arrived at our location, and then, at 1624 MDT (2224 Z)…
T-TIME!
You see, in most years, a tornado is such a rare and amazing event to witness for any storm observer. This year, I had experienced lousy luck with tornado photography in what has been a banner season for some others. In most cases (e.g., Bowdle SD, Faith SD, Campo CO), I wasn’t available to chase on the fantastic day in question. On one (10 May, OK), I (along with some other very talented chasers) got on the one storm that refused to produce anything more than a brief spinup while observable. On another (16 Jun, SD), the storm blocked the only safe road access to it with flooding and hooks filled with both precip and precip-wrapped tornadoes, while also going nuts on the other side.
After all that tornadic frustration, then, it surely felt good to see one that was not low-contrast, rain-wrapped and/or too brief to photograph, even if it was a small and otherwise not very newsworthy hose. The tornado slowly roamed wide-open land and, to our knowledge, hit no structures of consequence — just the way we like it. As seen from about 3-4 miles to its E, the tornado manifest initially as a tapering cone (zoom), with two episodes of visible ground contact. The first is shown in this zoom (see wide angle structure view), followed by a few minutes where neither condensation nor dust was evident under the base of the funnel (wide angle structure view), followed by a few minutes where full condensation planted again.
That vacillation was described by some observers as separating two tornadoes that occurred from the same vortex (by definition, a tornado must have ground contact), while others deemed it as one tornado with a weak interlude. What is a tornado? The ground was soaked out there, minimizing dust, although it did lose full-condensation again before lofting some combination of spray and dust (super wide, with storm structure). The tornado started to wrap deeply back into its occluding mesocyclone, then roped out.
Tornado-wise, that was all the storm could do. We felt fortunate to get there just in time! We also had to bail east, off the high plateau, because hailstones of 2 inches and larger in diameter started falling around us with discomforting splats and thuds right as I was shooting the last rope-out photo. We got out from under the vault with no hail impacts, then headed S and E in a very difficult effort to find a good W-NW view of the weakening supercell that wasn’t overly obstructed by terrain. Some others we know weren’t so lucky with hail. At that vantage, we encountered the Tempest bunch with Chuck, Chad Cowan, and Bill Reid, here shown calling for lodging from behind two giant hail craters patched with duct tape. Not far to our W, as the tornado began to narrow, that part of the vault immediately downshear from the low-level mesocyclone unceremoniously heaved forth gorilla hailstones up to 4 inches in diameter. It’s a good thing nobody was hurt by that hail (a vastly under-appreciated injury hazard in storm observing)!
The supercell moved over progressively more stable low-level air while attempting to backbuild, and eventually just died. That left us with no storm and some daylight, which we used for traveling to our motel in Sidney. On the way down toward I-90, we stopped to photograph an abandoned farm with soft stratocu and baby-blue sky in the background. We then hopped on the Interstate for a very unusual (for late June!) plunge through a late-afternoon regime of cool fog and mist, in the stratified air mass E of where the supercell had been.