Sunday, May 20th would be my fifth day driving for Tempest Tours and would also be the fifth day in a row that we would be encountering severe storms. At 13Z the SPC already had a Day 1 MDT risk for parts of south central OK. By 1630Z they had moved the moderate risk further north to the I-40 corridor in OK, apparently due to northward movement of outflow boundaries from the previous nights MCS across much of southern OK. The Dryline was expected to easily mix eastward to the I-35 corridor by early afternoon, so we knew we would need to target an area east of I-35 in the vicinity of maximum convergence near one of those old outflow boundaries. We started eastward from Vernon, TX by Noon. On this day, Bill Reid (Tempest Tours Director) and I would be in the tour van following behind Martin Lisius in his chase vehicle.
We sat at a rest stop near Jolly, TX trying to decide whether to head further east or southeast ahead of the dryline into TX or head north and east into OK. There was a persistent line of cumulus clouds bubbling to our north--and they were looking better with the passage of time. We pursued this apparent area of convergence north on RT 81 to near Waurika and then east on RT 70 towards Ardmore. There were several decent towering cumulus clouds visible as we approached Ardmore, with the most impressive one to our northeast somewhere in Pontotoc County. This was to become our target storm. Along the way we learned that the SPC had placed parts of central and eastern OK in a PDS box by mid afternoon. We were also hearing reports of severe and possibly tornadic storms near Ponca City well to our north. There were also severe warned storms to the west of OKC. We stuck with our Pontotoc storm for what seemed like an eternity. We finally left it go several miles east of Ada. Even though it had a severe warning, it just didn't look that impressive anymore. While we were bidding our storm farewell and pondering whether or not to head after those "better" storms to our north, Martin turned around and spotted an impressive new anvil back to our southwest--where we just came from! We now had a new target storm, and this one should be easier since it will be coming to us. At first we could not find it on radar, but 10 minutes later and there it was…one, two, three returns and growing fast!
Just as we were making our exit southbound on RT 99/377 from RT 3 Martin yelled "tornado, tornado, tornado"…but by the time we exited it had already lifted. The time was 6:28 PM CDT as Bill phoned in a tornado report to the NWS. We filmed the remnants of the somewhat distant cone well off to our southwest. The best option seemed for us to continue south a bit, and away from the light anvil rain. This would give us a better look to the west as the base, and any tornado, approached our location. At 6:43 PM a deep and ragged wall cloud formed with a nice inflow feeder tail extended northward and towards the ground. At 6:49 PM the second funnel snaked it's way down to nearly ground level. Unfortunately, a line of distant trees prevented us from seeing any circulation on the ground, but I feel certain that it had to be there. At 6:53 PM as this funnel drew back up into the cloud base, a new needle shaped funnel immediately descended, again to nearly ground level. This one lasted another minute or so and we had excellent backlighting for the entire event. Rain began to move in from a new storm off to our southwest as our tornadic storm began moving off to the northeast.
During the next hour, the storm continued to produce a series of very large wall and/or funnel clouds as we pursued it into Coal County. We finally ended the chase somewhere along highway 131 northeast of Coalgate. Everyone relaxed while we filmed a colorful sunset on the western horizon, and at the same time watched the retreating storm towers moving off to our east--always a nice wind down after a hectic chase.
Photo copyright Brian Morganti.