Afternoon Towers, Twilight Flashes
Seminole & Tecunseh, OK
15 Apr 13
SHORT: Struggling but occasionally photogenic convection near Seminole OK followed by lightning observation on back side of twilight storm complex.
LONG: During the day, a cold front had hung up along a weak frontal-wave low about 40 miles to our SE, closer than previously expected. While driving home from a dental appointment, which followed a day shift at work, two main things were on my mind–the Boston bombing, about which I learned at the dentist, and the towers going up on that boundary, visible to the SE.
Storms were more palatable to contemplate than the other grim issues of the day, so I headed home and picked up Elke for a short trek E. The better environment for photogenic, diurnal supercells was in north-central TX, NW of the Metroplex; but that was too far to reach before dark. We were hoping the cap could break closer to us, along an increasingly well-defined inflection point that lay nearly stationary over the area between Wanette and Konawa. That point also corresponded to the intersection of the frontal zone with a confluence line extending behind it to the NNE, and was persistently focusing the deepest (albeit still cap-dominated) buildups.
This part of Oklahoma is hilly and moderately forested, so high spots with good visibility are rather scant. During the couple hours or so before sunset, we waited at two places along US-377 S of Seminole–one right on the boundary, and another just to its N with better visibility. From the first, we saw one Cb erupt on the inflection point, briefly acquire strong radar reflectivity, then tear off to the NE, along the confluence line but also on the cold side of the boundary.
From the second stop, closer to Seminole, we photographed intervening towers with crepuscular rays, as a newer storm developed to the SW. The second Cb approached, skinny and pockmarked with holes, but beautiful to behold nonetheless. That likewise withered, so we headed into Seminole to grab some fast-food dinner and await further developments.
After supper, we saw a multicellular cluster forming back on the frontal wave and inflection to the SSW, and decided to get on the NW side of it for sunset color. Several cells emerged from that mess, including:
1. a sunset-illuminated left mover W of Tecumseh,
2. a right-moving supercell that we actually blew off because of its positioning on the dark side of the cluster, and
3. another left-mover to our E that was buzzing with a lot of in-cloud lightning discharges. The sky actually was darker than the photo makes it seem, due to the length of the exposures. Still, I wanted to strike that fine balance between bringing out the convective structures while not exposing for too long and blurring cloud features on a fairly quickly moving storm. How quickly?
Since then I’ve created a time lapse of the tripodded lightning shots I was attempting, so that you can gain some appreciation of the beauty of the third cell as it cruised fairly rapidly across the twilight skies to our SE. Please enjoy it. The time lapse spans six minutes, so you can see the fairly fast translation of the storm. Dial the speed meter up to the max level for full effect.
It was a mild, beautiful evening to watch the dynamic sky!
Melting Hail and Singing Frogs
Mulhall to Stillwater and Ripley OK
14 Apr 13
SHORT: Intercepted marginal/intermittent supercell–pretty storm–between Mulhall and Perkins OK.
LONG: Another day waking up during the late afternoon, after a night shift, offered a conditional opportunity for storm observing. In a year already shaping up to be sparse for such activity, this day offered at least marginally suitable wind and moisture profiles along or near a cold front, somewhere between OKC and southern Kansas.
One major concern was that any storms forming along the front, near and N of the KS border, would be undercut by the frontal air mass; so I played wait-and-see with shallower convection to its south. Finally, a clump of deep towering cumulus became apparent on visible satellite imagery NW of OKC, giving that look I’ve seen many times before of an incipient storm genesis area. Seeing that, I plotted a likely storm-motion vector that would take any resulting activity across I-35 W of SWO, threw the gear into the vehicle, and zigzagged to the Interstate to engage the prospective quarry.
As I passed downtown OKC, I could see deep towers to the NNW-NE glaciate. Radar reflectivities showed growing echoes in the same area, the spawn of the upward-motion zone responsible for those early towers. By the time I got to the high overlook near Mulhall, a series of mostly high-based and small (but deep) towers to my WNW-W were evolving into a more discrete and distinct storm.
From even these early stages, the storm was pretty, but had a pronounced core plummeting through the middle that limited the size of the upshear part of the updraft. This general configuration continued throughout its remaining lifespan, although the updraft did grow appreciably as it approached I-35 and moved into higher-PW boundary-layer air. I headed E to SWO a.k.a. Stillwater a.k.a. Stoolwater, then as the storm assumed marginal supercell characteristics, dropped back S toward Perkins to let it approach. The storm was high-based as expected, outflow-dominant, still with a small updraft, but severe-warned due to hail.
Knowing the tornado potential was next to zero, I let the rear-flank downdraft pass overhead then followed along behind the storm for a potential sunset view. In the Ripley area, still on the back edge of the rear-flank core, I encountered some hail up to about 8/10 inch in size, and reported that via the NSSL-PING app. A garishly painted tour vehicle zoomed east, into the core; but I opted for the colorful side of the storm, spread out beautifully across the eastern sky into which its slowly shrinking form receded. The earlier high-PW air began to be offset by diabatic surface cooling, and the storm spun down from the Perkins area eastward.
Cool, earthy aromas of fresh rain, melted hail and slightly pounded vegetation was welcomed by a chorus of frogs–something very seldom heard in these parts during the past couple of hot, drought-inflamed years. This was the full-sensory experience of storm observing, where even the feel and taste of the air was fresh, clean and wholesome.
After relaxing and enjoying the experience for a spell, I headed back through Perkins for a quick bite of fast food, then S down US-177, I-40, OK-102, and OK-9. It was a fun “backyard” chase that was most welcomed, while still getting me home in time to spend some time with my daughter and beautiful bride (who stayed home) before work.