High Plains Lightning Festival

July 7, 2011 by · 1 Comment
Filed under: Summary 

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.

A Real Stretch

June 1, 2011 by · Comments Off on A Real Stretch
Filed under: Summary 

Okeene and Karns, OK
23 May 11

SHORT: Observed small tornado W of Okeene OK and nontornadic supercell E of Greenfield OK.

LONG:

This “day before the day” heralded the beginning of the long-advertised “undercutting Pacific jet”, and impingement of a strong, broadly cyclonically curved upper wind max over the southwestern CONUS as a 500-mb cyclone closed over the Pacific NW. I much prefer patterns like this for observable supercells than closed, stationary to retreating northern-Plains lows like we had just seen.

A strongly difluent upper height pattern spread over the southern High Plains late in the afternoon with subtle height falls occurring across much of the region. The presence of a dryline that was
1. Beneath those height falls and
2. Bounding the west rim of a rich moist sector (at least over the TX portion)
…was a high-confidence scenario, the specifics being maxima in low-level lift versus strength of capping into evening.

Accordingly, Jack Beven and I, in caravan with DF’s “Dude, Three Chicks and a Dog” chase team, headed W on I-40 to await storm initiation along the dryline in a strongly heated and increasingly moist air mass.

Along with Howie Bluestein, Dan Dawson, Jeff Snyder and other scientists and students accompanying OU mobile radars, we waited and shopped at the Cherokee tribal store on I-40 near Calumet, until echoes appeared to our SW, W and NW. We parted with the OU crews, briefly stopped to watch some high-based junk SW of Watonga, then targeted the much more healthy Fairview/Okeene storm.

In fact, the storms SW of Watonga were everything but photogenic; and we still were in transit northward Okeene when we caught a view of a suspicious lowering under the emerging base W of Okeene. In a rare event for me, my first photos on this day therefore were of a tornado!

By 1618 CDT, when we pulled over along a section road 3 S Okeene, the lowering had become a well-defined funnel cloud about 5 NW of us or ~4 W Okeene. It was tilted nearly horizontally (wide-angle with foreground storm structure), and already tornadic based in dust-whirl reports by closer observers. Time was 1618 CDT. The newer updraft base almost overhead seemed to be the next candidate for a mesocyclone formation/occlusion process; but it actually moved N and got absorbed into the forward flank, vanishing in the process.

Meanwhile, we witnessed, photographed and reported the 6-minute tornado from the same vantage as a debris cloud became more and more apparent (unenhanced and super-enhanced photo). Shortly before the tornado dissipated, the debris cloud got displaced astonishingly far S of where the condensation funnel met the cloud base. Clearly the stretching term of the vorticity equation was at play here.

We stayed with the storm for about 45 more minutes just E of Okeene as another small thunderstorm formed to its S, moved over us with frog-strangling rain and closely slamming CGs, then merged into the main updraft region. This pathetic state of affairs left the supercell demolished as a discrete entity. What was left merged into a massive multicellular morass extending some 70 miles E-W across the area. Now what?

Onboard radar feeds tempted us intensely with displays of a solitary supercell about 75 miles to our S near Gotebo, and there was plenty of daylight to head down there and spend some quality time with that storm before dark. Off we went, photographing a smaller cell to our SSW over Watonga. (which would become the supercell E of Greenfield) and later a distant presentation of the convective mass we had left.

That Watonga storm looked rather innocuous as we passed under its early updraft base in and S of town. However, by the time we reached Greenfield and around to the S side, the convection grew explosively into a full-blown young supercell with bright, hard-looking updraft towers boiling up the back side. The upward eruption of the convection easily was visible in real-time via our eyeballs, as was the onset of helical turning in the midlevels, white turrets and cauliflower tops rocketing skyward and veering rightward like daddy likes to see.

We didn’t intercept this storm; it intercepted us. The supercell blossomed right besides us on the way S, in an environment not seeming too different from more mature supercell to which we had been aimed; so we diverted from plan, maneuvering the backroads NE of Karns into the near-inflow region of the Greenfield storm instead. Its first mesocyclonic occlusion attempt happened just to our NNW with a well-defined, if elongated, wall cloud that rotated only slowly. Rotation tightened considerably after the mesocyclone became deeply occluded, slotted and nearly cut-off from the rest of the storm, having been kicked way back out the NW side of the storm. Alas, loss of buoyancy overcame stretching; and the circulation perished.

After that, several areas of weak-moderate rotation materialized along an increasingly elongated cyclonic-shear and convergence zone; but the supercell itself was getting weaker and more strung out. We left it and headed S on US-81 through El Reno, once again headed for the initially intended supercell still a little over an hour S of us; but that storm died before we got past Tuttle. Little did Jack and I realize we were crossing the path that a certifiably violent and deadly wedge tornado would take the following day.

We enjoyed seeing Jim Leonard in the field as well as the aforementioned OU folks, and had a fine dinner in Norman with Matt Crowther, Betsy Abrams, Greg Stumpf, and my beautiful bride Elke, who couldn’t chase on this day. It was a fine and fitting end of the “day before the day” setup. What a wild, frightening, intense, and historic day the “day after the day before the day” would turn out to be…

2010 Chase Season Dénouement

August 14, 2010 by · 1 Comment
Filed under: Summary 

22 Jun 2010
Southeast WY to North Platte NEb

SHORT: Outflow-dominant supercell observed twice — once in SE WY and another in NEb Panhandle. Gorgeous sunset supercell S of Paxton NEb.

LONG: We were hoping for one final photogenic supercell for our chase vacation, and instead got two.

A piping hot lunch at a local cafe in downtown Sidney NEb, featuring a platter of smashed and fried Rocky Mountain oysters, settled down hunger’s restlessness just long enough for us to watch satellite imagery on the mobile phone, seeking first signs of convective initiation on the Laramie Range to our W. This area would experience favorable upslope flow, decent low-level shear and deep-layer winds, along with sustained surface heating in the absence of any appreciable, antecedent cloud cover, but moisture seemed a tad on the scant side. Once the first towers started to fire NW of CYS, we hopped onto I-80 and roared westward.

By the time we got to Pine Bluffs WY, deep towers were visible with glaciation to our NW. We could see the cloud bases easily, so we fueled at a truck stop there as I chugged down a cold, delicious A&W float. I also reserved a room in LBF for the night using a combination of forecast storm motion and positioning needed to go back home the next day, while watching for a storm to congeal and organize from the agitated area. Soon, it did, and we took off W through Burns and then N, retracing in reverse a segment of our chase path from the tornadic Chugwater event two days prior.

True to the lack of more robust moisture, the bases seemed uncomfortably high, and I was troubled further by how fast the cells started moving E off the mountains as we approached. Was the convection already spewing outflow? Yes! We barely beat the storm to the intersection of WY-213 and WY-216 W of Albin, near which I shot this photo looking W. Yes, there were updraft bases all right, but they were being undercut very quickly by wickedly cold currents hurtling SE from the precip cores. We headed E on 216 to Albin, having to make a decision there either to:

    1. Take unpaved back roads and stay closer to an outflow-surfing wind and ice machine, risking its outrunning us for good somewhere not far E of the WY-NEb border, or

    2. Shoot back down to I-90 and bust eastward at higher legal speeds so we could stay abeam and eventually get back ahead of the storm on a north road.

Although I’ve seldom seen such an outflow-dominant storm recover to produce tornadoes, it has happened on one occasion. Furthermore, such storms can produce interesting and sometimes beautiful cloud formations, especially out on the high plains. The decision was easy.

Meanwhile, before zooming down to the Interstate, we watched the storm cross the road to our N, spying a suspicious-looking but very short-lived formation buried in a mesocyclonic notch region (enhanced crop-n-zoom of previous image). That feature quickly vanished, and the whole messy and wild-looking process roared past.

By the time we got just the few miles S to I-80, the storm already had gotten well off to the NE, brilliantly festooning a deep blue sky (wide-angle view from I-90 near the border), with a high and ragged base visible on the trailing flank. That, along with the main updraft base of the storm to our left, were visible as we cruised E to Sidney, then N toward Gurley — in the process retracing a late-day segment of our trek from the previous season’s intercept of the LaGrange WY supercell. For our nearly continuous view of the updraft while driving, and several chasers who were closer at that time and didn’t see any tornado, I had to question the “sheriffnado” reports just E of the border in NEb.

We got directly ahead of the storm again E of Gurley, watching its somewhat-lower base with a small, shallow wall cloud developing to our WNW (wide-angle view) while a deck of low clouds formed overhead. The storm itself was decelerating markedly, and its own outflow boundary appeared to outrun its main reflectivity area (and mesocyclone aloft). I got a dread that the supercell wouldn’t last much longer; and it certainly did not. A zoom view shows the wall cloud that was surrounded by translucent precip. Within minutes, a fuzzy gray bowl of precip appeared right in and under the wall cloud, descending and expanding and obliterating the wall cloud as it reached the ground, and making a splendid example of a tornado look-alike.

Was this a descending reflectivity core (DRC) that came down in a very deleterious place for any low-level mesocyclone’s development and survival? It sure seemed as such. Here’s the view 3 minutes later, when the precip core further expanded and utterly obliterated the cloud base where the wall cloud previously had dangled. Within 11 minutes more, the outflow had gone past, the low clouds cleared away to reveal an astonishingly rapid storm demise!

Thinking that was it for our chase season, we headed E toward LBF, only to see a stunning and spectacular convective eruption to our SE, S of Paxton, beneath a waxing gibbous moon and shortly before sunset. As this storm evolved into a short-lived supercell, we admired the amazing spectacle from a corn field a couple of miles S of the Interstate, until an inverse relationship between amount of sunlight and mosquitoes hastened our resumption of the trip. What a wonderful way to close out the last chase of Spring 2010!

When we settled into our room in LBF, the clerk remembered my call and said we were smart to do what we did many hours before; all the rooms in LBF were booked up solid! After 11 p.m., we noticed a dramatic increase in lightning to our N-W, as storms erupted along the outflow boundary. While cruising S of town in search of a good vantage in that direction, the storms weakened again, precluding any decent lightning photo opportunities, though we did salvage a nice look at lunar crepusculars around an altocumulus deck.

This was a rewarding day, one that left us in ideal geographic position to do something we had wanted for a long time: pick up a stone fencepost from one of the quarries near RSL. It would be right along the way home the following day. Our adventure in doing so was a marvelous glimpse of Americana, chronicled in more detail in this BLOG entry. The dénouement had been written on our chase season – one that was, at times, agonizingly frustrating, and at others, as fulfilling as can be. What adventures await in 2011?

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