Most tornadoes in the United States move from southwest to northeast, but once in a while, storms can do something funky. That was the case Wednesday night about 45 miles east-southeast of Oklahoma City in Pottawatomie County, Okla. Earlsboro — a community that may have been hit by three tornadoes in three days — hosted a meteorological marvel.
Nobody got any video of the unusually errant twister doing its dance, since the funnel performed its atypical feat in the dark. But damage reports from the ground revealed that the EF2 tornado, with winds of 135 mph, traced a nearly perfect counterclockwise ellipse along its 3.38-mile path.
The same storm produced a second tornado moments later that followed a more conventional path to the east, which also caused EF1 damage along Ew121 Road.
The National Weather Service in Norman, Okla., tasked with investigating the oddity, found damage on the northeast side of Earlsboro. The first tornado, dubbed “Earlsboro 1,” had breezed passed town, only to make a left (northward) turn and then curl back southeast. In the process, it sideswiped a few buildings on the northeast side of town near the public school on Stargell Avenue.
The agency tweeted a map depicting the tornado’s path; it shows Earlsboro 2 touching down moments after its predecessor lifted. The Weather Service is working to ascertain whether the second may have been a continuation of the first tornado, or was a distinct separate vortex.
“The evidence would suggest they were from within the same [rotational] couplet,” said Forrest Mitchell, observations program leader at the Norman office. “Or at least within the same mesocyclone.”
How it happened
A mesocyclone is a rotating updraft that fuels a severe thunderstorm, from which more concentrated funnels of rotation may touch down. It’s not uncommon to have a “tornado handoff,” or one lifting as another forms. Ordinarily, the first withers and dies and is tugged to the left by the counterclockwise-spinning cloud it’s attached to above.
What makes this event special is that Earlsboro 1 didn’t get stretched into oblivion — it completed its loop, dodging the rush of cool wind in the “downdraft” that would choke it off. Then it rode southeast, driven by the slowly gyrating mesocyclone above.
It may be that a rear flank downdraft (RFD) surge, or a rush of cool, dense air on the back side of the circulation, helped shunt the tornado to the southeast. Somehow it wasn’t annihilated by that cool air. Perhaps the RFD was unusually mild, supporting the continued buoyancy necessary to sustain the tornado. Warm RFD surges are rare but happen. Research is ongoing about the potential role of warm RFDs in the formation of tornadoes.
“We have not seen too many cases like this, but that doesn’t mean it’s as rare as the few cases we’ve seen,” Mitchell said. “In fact there was a point in time when we were looking at this wondering if we were seeing a satellite tornado.”
Satellite tornadoes are secondary whirls that orbit a larger tornadic circulation. They’re born out of the same mesocyclone in environments with through-the-roof vorticity, or spin. Tornadoes can also merge or shed off smaller vortices, particularly in high-end environments.
How rare is it?
Mitchell has been at his post in Oklahoma since 1990 and before that spent a decade as a Weather Service contractor. He’s seen plenty in his four-decade career. Wednesday’s events jogged a memory from the infamous May 3, 1999, tornado outbreak that also sent a buzz saw F5 tornado through Moore, Okla., killing three dozen people.
“This has been a window-opening view into something that bears further investigation,” he said. “Now having said that, I recall during the May 3 outbreak something in Greenfield in Caddo County. I spoke with a farmer out there who described a similar situation. He took shelter, stepped outside to take a look, and he saw a tornado to his immediate southeast moving in a northeasterly direction … but he told me he then had to seek shelter again because he noticed another tornado coming from behind him. And it curved from the northwest to the southeast and actually passed between his house and his barn at the time while the first tornado that he noticed was further southeast of his location.”
Tornado path oddities
There are other examples of tornadoes making loops, particularly in slow-moving supercells that feature both cyclonic (counterclockwise-spinning) and rare anticyclonic (clockwise-spinning) tornadoes.
- On the night of June 3, 1980, a massive supercell thunderstorm dropped seven tornadoes on and near Grand Island, Neb. The first tornado of the family did travel along a small loop, but not nearly as wide as the roughly mile-wide loop made Wednesday night. Three of the others spun clockwise, and virtually every funnel that night either carved arcing paths or looped.
- Another nearly stagnant severe thunderstorm on May 28, 2013, near Bennington, Kan., produced an enormous tornado that promenaded in a cyclonic loop for over an hour.
- Semicircular cyclonic (counterclockwise) half-loops are more common, with a left turn typical at the end of a tornado’s life cycle. That happened in Lockett, Tex., on Wednesday night, when an EF3 tornado took a dramatic left turn into town. Widespread damage was reported.
- The El Reno, Okla., tornado of May 31, 2013, that killed tornado researcher Tim Samaras and his two chaser partners had a similar semicircular path. Mike Bettes, a meteorologist at the Weather Channel, was caught off guard, his crew and vehicles thrown violently by the tornado’s ferocious winds.
Once in a while, storms can defy all logic and produce tornadoes that move “backward,” from northeast to southwest. That happened with the F5 Jarrell, Tex., tornado on May 27, 1997, during which a thunderstorm slowly moved southwest along a stalled boundary. Otherwise, northeast to southwest-moving tornadoes often occur during landfalling tropical cyclones as rotating rain squalls make landfall.
Tornadoes also can, and do, merge. That was the case when two strong twisters appeared to combine in South Carolina on April 13, 2020. Another pair of tornadoes merged in the Texas Panhandle on March 13, 2021, the result of a decaying tornado being sucked into the next member of the storm’s tornado family. And dual circulations appear to have merged during the Nov. 13, 2021, outbreak on Long Island.
“I’ve been studying these for 40 years now, and we’re just scratching the surface,” Mitchell said, still in awe over what transpired Wednesday. “We’re just getting started.”