The US-412 Supercell

April 9, 2011 by · Comments Off on The US-412 Supercell
Filed under: Summary 

Enid/Garber OK
8 Apr 11

SHORT: Modest, yet enjoyable supercell observed east of Enid that developed in the warm sector (not on the dryline).


The initial thinking from prior days, and early on this one, was that a dryline storm could fire somewhere over western OK in a zone of intense heating and mixing that would overcome strong EML-based capping, and move eastward into more moist air for a short time amidst an ambient kinematic profile most definitely suitable for storm-scale rotation. Instead, we ended up with one warm-sector supercell out of several! Here’s how…

A persistent zone of northward-moving, gradually deepening cumuli, corresponding to a zone of intense heating and mixing east of the dryline, formed during early-mid afternoon over NW TX near Vernon, and also, in an area of weak surface wind-shift and mass convergence as evident in both plotted charts and objective analyses. This immediately caught our attention (Corey M, Rich T and I); and we began to ponder this as a potential storm genesis source. The later it went, the farther N it would go; as the combined surface and satellite feature was moving N across I-40 and into the Kingfisher area by the time we left. After Rich picked up his son from school; we all met at Battlestar Norman and departed for El Reno via the Highway 9/turnpike bypass, intending to head N on US-81 from El Reno.

While near the former Kelvin’s Corner, we spotted turkey towers with glaciation to the NW, a good sign of deep ascent that encouraged us onward. VIS imagery showed a boomerang-shaped field of deeply enhanced Cu, much of which we couldn’t see visually from a distance because of smoke-related boundary-layer haze. The inflection point of this boomerang was moving N from the Kingfisher area; so we headed that way. That’s where the first echo–the eventual Enid storm–erupted while we were approaching Kingfisher.

We cruised up to Hennessey as the nascent supercell grew, towers rolling up its near (SW) flank and backshearing. The storm lost some organization on radar during an initial storm split; but its updraft towers till looked robust visually. In accordance with that encouraging sign, the right-split recovered nicely from the initial body-blow as we maneuvered E on OK-51 and N on OK-74 toward Covington.

Our initial views of the underside from SW of Covington (no photos…stupidly, I left the camera in the back of Rich’s vehicle while we were driving) revealed a high, somewhat disorganized base. As we approached from the S, the eastern portion of the updraft region began re-ingesting a partial mix of rain-cooled air. Huge chunks of scud formed and rose, appending themselves together into a tall, ragged wall cloud that rotated slowly, assuming a triangular shape for a short time. At one point, the point of the triangle lowered about 4/5 to the ground from a very high ambient cloud base; but rotation was slow at best, and no dust or debris could be spotted beneath. This seemed to be the “almost a tornado” phase some chasers described.

As we reached 412 and turned E, the storm was in its best-organized phase–peak midlevel rotation in SRM displays and that ragged, occasionally low-hanging and pointed wall cloud with obvious cyclonic shear. The meso wasn’t strong enough to pull a great deal of precip around yet. As we continued E on 412 and got abeam of the circulation, a lot of the scud evaporated, as if the wall cloud were disrobing to reveal a peculiar, tilted but mostly horizontal cloud vortex. This feature narrowed into a skinny, nearly horizontal funnel, somewhat bent, and way above the ground. We didn’t deem this an imminent tornado threat.

By the time we pulled over at an optimum vantage, and I got out the camera, the laminar, horizontal, funnel-like feature to our N had vanished; and the ragged wall cloud was eroding away to reveal the more ambient, high base again. At this stage, the structure reminded me a bit of the 22 May 7 supercell near St. Peter, KS, but of course, without the tornado! Storm motion slowed down; and we were able to maintain a leisurely pace east on US-412 with a couple of long-lasting stops to observe the supercell’s high but well-structured underside to our N.

The storm attempted a couple of occlusions, including this one with a well-defined downdraft slot and precip cascade, while surface-based inflow still was screaming from the S and buffeting us reasonably well. Soon, however, the inflow calmed a bit, and the storm took on a more laminar, elevated appearance as it approached I-35 (shot looking NNE with CG from the vault region).

As the storm continued to weaken, we bid it a fond farewell, and headed S on I-35 toward home.

This was a fine first chase of the season, a good opportunity to work out some kinks, test new equipment, and re-learn needed lessons (i.e., “Self, you forgetful doofus, keep the damn camera in reach while someone else is driving!”). It was great to get out on the Plains again and watch a supercell–a cathartic release from the psychological imprisonment of a long, cold winter. Even though we are mired in deep drought here in central OK, we bear hopes for at least a few more photogenic supercells within reasonable driving distance the remainder of the season, as prospects for the big events already appear to be displaced far, far away.