Daily Archives: 20 April 2013

2013-04-17: Wall clouds in SW OK

KFDR reflectivity image of the Faxton storm
Cutting south across the forward flank of the first Faxton, OK storm on April 17.
It was my first day back at work after a long week of travel that spanned nearly 15 degrees of longitude. (More on that later.) I went into work extra early, and managed to scramble a chase partner (Gerry C.). We departed the NWC just after 2 p.m., and headed southwest on I-44. We initially targeted a storm west of Anadarko, OK, only to abandon it quickly when its high cloud base made frontal undercut evident.

Next, we cut across the forward flank of a tornado-warned supercell passing over KFDR, intercepting it near Cache, OK. Sitting on top of a hill on Cache Road just north of Faxton, OK, we observed a wall cloud to our distant southwest that extended a few enticing purple scud fingers. However, it quickly filled from behind with emerald green and gusted out toward us.

Faxton, OK Wall Cloud
Faxton, OK wall cloud about 5 p.m. CDT, as seen from Cache, OK
We escaped east toward Lawton with numerous other chasers, but were overtaken by the advancing core. A few nickel-sized hailstones thumped against my roof. I dropped a few miles south on SW 82nd Street and allowed the Faxton storm’s hook to pass by us to the north.

By this point, it was evident that a second supercell – following an almost identical track over KFDR and Manitou, OK – was now the tail end Charlie and the preferred target. Proceeding west along Baseline Rd., we stopped near the intersection with Indiahoma Rd. where we had a good view toward the west and a new wall cloud. Unfortunately, that wall cloud met the same fate as the last one – after rotating lazily, it grew increasingly Z-shaped as an advancing gust front pushed it out from behind.

It was growing darker, and we both needed to return home for logistical reasons. As we merged back onto I-44 at Lawton, we heard a spotter report of a tornado near Ft. Sill, a few miles to our northwest. Our view was blocked by trees, but we could see a dark lowering beneath the cloud base in that direction. We pulled off I-44 for a few minutes to observe, but never saw a tornado or the reported power flashes. We missed the Grandfield tornado, which happened even farther to our southwest, after dark.

By then, the southwest-to-northeast oriented line of supercells was now situated over I-44, signifying a slow and messy return drive. Lou W., who had been nowcasting for us via text message from back in Norman, suggested that we drive straight east through Duncan to I-35, and return to Norman that way. It added about 30 miles to our drive length, but was precipitation-free for all but the last 10 miles. We took the Lindsey Street exit just as our old target storms congealed into a mini-bow. The next morning, my home rain gauge had 2.1 inches of refreshing rain in it.

For your amusement, here’s a video clip from Chris Novy showing spotter network activity during the 17 April event. Despite the number of glowing green ants, we didn’t run into any horde-related issues. We found decent parking spaces and observed safe driving habits all around.