Cumulonimbus Shrivelus Patheticus

August 19, 2009 by · 2 Comments
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North-central OK, 19 Aug 9

SHORT: Promising young storm E of END shriveled as I reached it.

LONG:
As the day wore on, it became progressively more apparent that some supercell potential would exist this afternoon along and N of an outflow boundary retreating N across central and NW OK. An unusual amount of mid-upper level winds for August spread over the area — 35-40 jt at 500 mb, with strongly curved and enlarged hodographs N of the vorticity-laden outflow boundary. It looked as intriguing as many late May or early June setups, ignoring the fact that the calendar read, “August.

I took the pickup to work for the first time today, and hadn’t yet equipped it completely for a storm intercept. While at work, Elke brought my handheld live radar and weather data module (i.e., I-Phone), and I borrowed an Oklahoma road atlas. She couldn’t chase and neither could Rich; and my shift ended an hour after others’. So it was just me this time, incognito in a pickup much like those driven by tens of thousands of other Okie residents on any given day.

Cumuli already were deepening in a persistent, agitated area of ascent along the NW limb of the old outflow boundary, in major and Blaine counties, before I left. Already equipped with camera gear, as usual, I took off straight N up I-35 as soon as the shift ended (5 p.m.), figuring the projected 20 kt eastward mature supercell motion would allow me to beat any storms that formed in the agitated area to I-35. Rich was impressed enough to issue a tornado watch, which seemed good to me.

Unfortunately, the atmosphere that I thought was flashing a middle finger toward the calendar instead flipped me off. One Cb erupted NW of END, seemingly destined to turn E and cruise along or just S of the KS border. I would have been in time to intercept that but it dissipated quickly.

A second storm blew up near END, in ideal intercept position; all I needed to do would be to head up to the US-412 exit and let it come to me. So I did. On radar the storm appeared persistent, neither growing nor shrinking much, as if it was fighting some adverse effect but still hanging in there. The updrafts looked alternatively robust then soft, then robust again, giving the same impression of a delicate balance that could tip precariously to storm demise or explosively to beats-honking supercell.

What happened? The former! By the time I got to a parking spot just W of the exit, the storm was a “chicken neck” updraft, showing some corkscrewing motion but also shrinking by the minute (above image). A multicellular MCS was taking shape in southern KS, out of reach for both the amount of remaining daylight and my desire to get home. The “storm” wasted away within 15 minutes after my arrival, leaving me to grab a terrible chicken sandwich at the Braums in Perry and head back to Norman.

This barely qualified as a “storm observed this year,” but I did hear a couple of lightning pops on the A.M. radio. I’ve certainly observed less (i.e., no development at all) in a few big CAPE, ample-shear setups along well-defined boundaries. At least I didn’t waste much time or fuel, and I got to break in the truck for chase purposes. It was a comfortable and roomy ride.

Thunder on Thunderbird

August 6, 2009 by · Comments Off
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5 Aug 9
Lake Thunderbird, Norman OK

Either I’ve been out of town, asleep, or at work for most of the best lightning opportunities in Norman this year. Last night, therefore, was a treat. After watching some recorded TV with my kids — namely a special on the Dallas Cowboys’ amazing 1993 season — I heard thunder in the distance. The radar loops showed some elevated storms firing over SW Oklahoma City and east of Lake Thunderbird. Both were sparking nicely by the time I went outside to look, so I tossed the camera bag in the car and headed a few miles over to the lake for some lightning viewing and photography.

My usual setup spot there for storms to the E and SE proved well worthwhile…for a couple of minutes! I only managed to get a handful of shots, one of which I was happy with (above and here), before the storms filled in on top of me. I had to wait out the rain and CGs for about half an hour. Photogenic lightning after that was very sporadic, and hit-and-miss (mostly missed, in my case). Nonetheless, the rain-cooled air refreshed and invigorated me, making the short trek well worthwhile, whatever the lightning photography results. Given our ongoing return to the summertime furnace, my lungs welcomed that cool, moist breeze like my stomach would accept a drink of water after a trek across the burning sands of Sonora.

After getting cored, most of the lightning to the SE and S was in-cloud and in-precip, though I did get a few shots of filamentous aerial discharges and distant CGs across the water. Some sparking and training echoes to the NW and W had me head to the other side of the bay for several shots of distant, core-edge CGs with the tan glow of OKC lights illuminating foreground clouds. Then the storms retreated, and it was time to saddle up and scoot on home.

Ragged Roger’s Rage of Rago

August 1, 2009 by · Comments Off
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20 Jul 9
South-central KS and north-central Oklahoma supercell

SHORT: On the way back from vacation in Colorado with Elke and the kids, observed a photogenic supercell over southern KS and northern OK.

LONG: Faced with a long drive back to Norman and the prospect of a day shift for me the next day, I sleepily pulled out of my in-laws’ place near Broomfield, morning sun in my face, eagerly anticipating late lunch and early dinner in SLN, and knowing that we would be bypassing the central CO and western KS storm potential along the way. We would have to depend on mesoscale accidents and luck to observe anything in the afternoon, when in central and southern KS, near the W edge of a cloud shield left behind by elevated convection early in the day.

As we proceeded E, the elevated storms kept firing across northeast and east Kansas, setting up some differential heating in an environment of favorable low level moisture and at least acceptable deep-layer shear. By the time we commenced to late lunch/early dinner at SLN, a supercell pair already had formed over southwest NEb and began charging S toward GLD — through which we had driven a few hours ago. This would include the storm that bombarded Alnado’s place with 4+ inch diameter hail and severe winds, as well as presenting him with a small tornado visible from his property.

After we cleaned out the Coyote Canyon buffet, I checked a surface map and some automated mesoanalysis data on the I-Phone, and saw a nicely defined, NW-SE boundary from near HUT-WNF, conveniently parallel to the mean wind vector, and collocated with the surface moist axis. That’s a good sign. Cu and TCu bubbled along it, seeming to be a couple hours from any serious mature storm (if ever). We headed S on I-135 in no big hurry, a small cell forming then dying on the bondary S of ICT and well S of us. As we hit Newton, the SW sky erupted with towers, and the ICT radar exploded with echoes near Kingman. A large, rather disorganized looking cluster of very high reflectivity sent a short-lived left split off toward the W side of ICT, while we cruised through town.

Given the presence of that vorticity-laden boundary and all its positive attributes (and positive SRH), we decided to wait at the Belle Plaine service area to see if a supercell could consolidate from the big convective mess, while anvil material spread in a massive shadowy umbrella across the sky overhead. Finally, it did, and we zigzagged WNW from Belle Plaine to take a look. We had a distant view under the storm at the time of the law-enforcement “rope tornado” report near Rago, and didn’t see it. Here’s a wide-angle as we approached, looking WNW from E of Perth.

The storm was moving hard right, toward the SE then SSE — a good sign for storm-relative inflow, but away from the higher SRH and moist axis along the boundary. I suspected its tornadic phase (if it ever existed) was early, brief and finished, and it would be “just” a pretty storm from here on. The storm began hammering the countryside in all directions with staccato CG bolts from the anvil, many miles ahead of the cores and vault. The sizzling CGs igniting several fires, and forced us to stay in the car most of the time until S of the OK border. Knowing it would herd us back toward I-35 and homeward, we chose to stay SE to ESE of the storm and keep observing.

The supercell developed several banded structures on both flanks (as seen from Corbin KS). This included a curious juxtaposition of near-ground smoke pooled along the forward-flank gust front, beneath a convective beaver-tail with a base, sandwiching a chamber of filtered golden light of the sunset hour (here’s that shot).

Meanwhile, with the storm bearing even more firmly equatorward, we found a stopping point S of Corbin near the border, and noticed two plumes of smoke rising into the updraft base (wide angle and zoom shots). These reminded me of the “Wicker smokenado” from the early 1980s that made national TV on Nova. Several lightning-started fires had led to a patchwork of smoke palls in all directions, including this one to the SE that formed a nice angle with the postcrepuscular storm shadow.

We reached I-35, photographing the twilight storm from the rest stop near Blackwell, as it crossed the border. Figuring this storm might not be crawling with live OKC TV trucks at this time of year (for once!), I called the OUN office to provide a field report, letting them know the storm looked flat, nontornadic, forced, and somewhat lofted atop its own outflow — despite the prominent hook and SRM couplet I was seeing on Vance AFB radar.

For once, I was not anticipating the prospective nocturnal light show. See, I performed any photographer’s dreaded blunder by forgetting my tripod on the trip. Most of the time, I improvised successfully by bracketing steadiness — rapid-fire shooting of low-light and/or high f-stop scenes in confidence that at least one shot would turn out sharply during a fortuitously steady time interval. This strategy has worked for me over and over in many other situations, but simply can’t be done with something as ephemeral as lightning.

As I drove, Elke began to marvel at the structure, which assumed the shape of twisted taffy, brilliantly illuminated by foreground lightning. Photos or not, we had to get off I-35 for a look! By the time we got back off the interstate, the storm’s sparking was becoming less frequent anyway, its structures flatter again, which made the challenge even harder.

Bring it on: I stand ready to face any challenge. Somehow, using the top of the car and some hand and finger contortions, I did get off a couple of decent lightning shots, including this one. It’s not as spectacular as some stuff I saw elsewhere from the western supercell, but I’m satisfied to have done the best I could under the circumstances.

The western supercell N of END tempted us, but it was getting late (after 10 p.m.), and I had that day shift the next morning to deal with. Tired from the extensive drive and from the trip as a whole, we simply headed back home, content and thankful to have seen and intercepted a rotating storm in late July. This made the sixth straight month I witnessed a supercell in the state of Oklahoma. How strange is that?

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