By midafternoon, the rest of the team converges on the rendezvous. Chris Karstens, the Iowa State grad student, always knows when he is within range of his fellow researchers. The silent TWISTEX frequency suddenly crackles to life with the voices of friends, trading joking insults and comparing observations.
Tony Laubach follows close behind in M3, along with Ed Grubb. Following the deployment briefing, the TWISTEX crew saddles up, confident in the day’s prospects. TOWER is securely strapped to the back of Tim’s probe truck. The mesonets are manned by some of the most competent chasers and atmospheric scientists in the field. The clouds are primed to explode. “It’s like you’re going to war,” Karstens says.
Best of all, they learn that VORTEX2 is sitting this storm out. The night before, the field coordinator’s vehicle had broken down. “In their defense, they had been going very hard. They didn’t get back to their hotel until 4:00 a.m.,” Finley says. “Everybody was pretty exhausted.”
With its unmanned drones, fleet of mobile radars, and vast mesonet array, VORTEX2 can cover every facet of a storm in a way the much-leaner TWISTEX never will. Since 2009, VORTEX2’s armada has seemed omnipresent, smothering every chase. “Everywhere we went,” Lee laments, “there were these VORTEX vehicles. And as soon as they arrive, our data isn’t worth a lot.”
But the project’s very enormity also means that any number of moving parts can break down. Wurman’s contingent is a cruise ship—slow to get moving, slow to change course. If the TWISTEX crew had thrown in with VORTEX2, they would have missed what is shaping up to be the most promising storm since the project launched the year before.
With their rival off-line in North Platte, Nebraska, there is no one else with whom to share the roads. The storm is TWISTEX’s for the taking. Despite the long odds of Tim’s gamble—the limitations of staying small and agile, the money problems, the risk of operating without Wurman’s mobile Doppler—it looks as if Tim has pulled it off again. If the new probe works.
Around four that afternoon, west of Bowdle, South Dakota, the mesonets travel north in a line, roughly a kilometer apart, down a narrow and winding dirt road. Consistent spacing between mesonets is paramount for data collection, and they maintain this distance with a GPS program Karstens has developed, called Sidekick, which displays the location of each vehicle on a map.
Lee can already sense that the day is about to get interesting. The mesocyclone to his west is pendant above the low rise of northern plain like a glacier, jagged and massive and all but kissing the earth. As the fields wash past, and the cars and radio waves fill with excited chatter, Grubb thinks he may have spotted telltale dust swirling along the ground. In M1, Lee identifies the storm’s clear slot, connoting the passage of the rear-flank downdraft. The updraft is organizing, shaped and smoothed by laminar winds. The show is about to begin.
“Okay, mesonet,” Lee says, “the way we’re gonna line up is [M1] will take the lead position. We’ll try to stay roughly half a kilometer to the south of the tornado path. Tony, you’re a kilometer behind us. M2, you’re a kilometer behind Tony.”
Arrayed along the flank of the storm, Lee orders the convoy to a momentary halt as they approach the mesocyclone. Any farther and M1 risks straying into no-man’s-land, the perilous pocket inside which the tornado could come down quite literally on their heads.
Without warning, a gust wails out of the west and rocks the mesonets, peppering the vehicles with rain and dust like bird shot. They’ve just penetrated their first RFD of the day. M1’s mesonet station reports a forty-six-mile-per-hour gust. The wall cloud—the low-slung feature at the bottom of the mesocyclone, from which the tornado will soon emerge—swings past M3, turbulent and ragged, like dirty cotton. On closer inspection, it appears to contain a possible funnel, or at least the earliest stages of one.
A palpitating lobe of condensation hovers just above M1, an indication that the mesocyclone is strengthening and accelerating. It’s preparing to focus the broadly distributed power of its slow turning into the tornado’s vicious knife edge. The storm bears away east-northeast, and the convoy begins to move north with it, proceeding deliberately, at no more than twenty miles per hour. As Lee and Finley scan the wall cloud, they notice again the lowering to their four o’clock. Tornadogenesis has a way of feeling both gradual and surprisingly sudden. The feathering lobe of condensation narrows, sharpens, and smooths until at last the tip is honed to a needlepoint. It swoons breathtakingly close to earth, then decays in filigreed shreds before retreating back into the wall cloud. Striated bands of stratus flood the swelling mass of the mesocyclone. The storm is feeding. “Wow,” Lee gasps. “This is something! We’ve got winds holding at forty [knots] out of the west-northwest.”
At a rate almost imperceptible to the eye, the funnel returns, building and lengthening, stretching inexorably toward the surface. “The thing is just cranking,” Finley says.
Now several funnels knife through the lowering. Is this the birth of the multiple-vortex? The radio waves are chaotic with real-time speculation. But within moments the sky has answered: the multiple vortices coalesce into a wedge. A welter of dust erupts from the fields, and the first reachable tornado of the season has officially touched down. Within seconds it becomes apparent that TWISTEX has a high-end twister on its hands. No need to cycle, to mature, to build angular momentum. This thing
