Hummer H3T: Storm Chaser
One Hummer H3T Helps Scientists Gather Data in Tornado Alley
RAF helicopter combat pilot Jacqui Wilmshurst left the military when the demand for chopper pilots dropped after the Brits scaled back involvement in the second Iraq war. “I never thought I would be able to use all the skills I developed flying a military helicopter, but this is it,” she explains, leaning against a six-wheel cab-on-frame truck with a large radar dish rising from its frame at a wayside rest stop in Kansas. “We have to navigate unknown territory, we have to be moving all day, we have to keep to a rigorous schedule, getting little sleep, and we have to focus sharply on the weather.”
Wilmshurst is speaking of the tasks she must do while storm chasing, a growing adrenaline-producing hobby and science that occurs every spring in the Great Plains of the U.S. Midwest. Chasing tornadoes has to be done by car or truck, driving sometimes 650 miles day after day, making decisions that predict the future of the day’s weather. Wilmshurst used a project called VORTEX2 as research for her new career, which she started at England’s University of Sheffield, the coursework for which delves into the psychology of fear caused by nature. Tornado Alley is the perfect environment for this.
Every year in the United States, about 1000 or so tornadoes touch down. A handful of these are strong enough to wipe out entire towns. Before the latest Nexrad radar of 1988, every tornado was a surprise, some killing hundreds as they destroyed small towns in minutes. The majority of these killer twisters take place in the unique environment of the Great Plains, where warm, moist air from the Gulf of Mexico meets cold air cascading down the Rockies at the beginning of every summer. Nowhere else in the world is there the volume of tornadoes as in this 900-mile-square area. When the entire town of Greensburg, Kansas, was demolished two years ago, just nine residents were killed that night, plus a police officer rushing toward the town to offer aid. Everyone else was warned and bunkered down.
But the average warning is only about 13 minutes, according to the VORTEX2 (Verification Of Rotation in Tornadoes EXperiment 2) scientists. Another 60 or so students and researchers assisted the project, utilizing 40 vehicles, all specially outfitted for gathering weather data. The data will help scientists lengthen warning times and improve tornado prediction accuracy. Fourteen of the 40 vehicles were intended to drive as close to a tornado as possible, deploy portable instrument pods, and then scoot away. Nine of these, however, are government minivans with plenty of space for computer equipment—but they are overloaded front-drivers with highway tires thrust into an environment filled with flash flooded dirt roads in the rural Midwest. This year, Dr. Joshua Wurman, head of the Center for Severe Weather Research, selected a HUMMER H3T as the 14th “probe” vehicle, responsible for deploying instruments during high-risk thunderstorms and in the paths of oncoming tornadoes, in places where previous probe vehicles have not been able to do so safely.
The five-week VORTEX2 project received $12 million in funding, mostly from the National Science Foundation and the National Oceanic and Atmospheric Administration, and included 10 radar-equipped trucks from CSWR, universities in Oklahoma, Pennsylvania, Massachusetts, and Texas and the U.S. Navy. Fourteen instrumented 4WD vehicles carried 42 deployable instrument packs, such as 120-pound “pods” (similar to those in the 1995 movie “Twister,” based on the original VORTEX project of 1993), and weather balloons from the government, and damage survey teams of veteran researchers. I was invited to join for the deployment. About half of the large storms the VORTEX2 teams identified last spring, but did not chase, were eliminated because the scientists determined the probes wouldn’t be able to deploy instruments on the poor road networks of lightly populated, lumpy-terrain plains.
Our H3T was a stock 5.3-liter Alpha, with the ZM6 Adventure off-road package, featuring three locking differentials to help extract the truck from flash-flooded ditches, and to pull the National Severe Storm Laboratory’s front-drive minivans out of the same ditches. The five-foot bed was covered with a 1.25-inch square steel tubing frame 26 inches tall, topped with an aluminum DiamondBack bed cover to protect three 120-pound instrument pods from hail and debris. A two-inch square steel tube 13 feet high was welded to the front winch ring brackets to mount the anemometer, temperature, and humidity instruments as high as possible.
Originally, we had worried the optional sunroof would be a problem with hail, although we mounted a Yakima roof rack and bolted a steel mesh to fend off falling ice balls. What we found is that, while we were frantically trying to drive ahead of a large supercell in Nebraska, we could look through the roof for signs of telltale storm rotation that precedes a tornado. The sunroof helped us keep a watch on the mast-mounted instruments to ensure they hadn’t been damaged by debris.
On one highway in Kansas, the Hummer was instructed to peel off from the armada and search down an unknown road to find a shortcut the six-wheel, 21,000-pound radar trucks could cross. Another time, we almost had to bushwhack: “Probe 14, we may need you to do some off-road driving,” Josh Wurman’s voice announced over the radio in eastern Wyoming, as the armada of VORTEX2 vehicles rolled along a winding two-lane highway northwest toward a developing supercell. The team was seeking escape routes to take should a tornado form in the storm, routes the rest of the vehicles could travel to get out of the path of any twisters, hailstorms, or high winds. It turned out the storm shifted and came close enough to the highway that our aggressive P265/65R18 tires weren’t needed this day.
During the project, we covered 12,600 miles in the H3T, getting about 13 mpg for the entire distance, with the truck carrying three to four people and 400 pounds of equipment in the bed and pushing the 26-inch-tall pod protection box through the air. We pulled the heavy steel instrument pods out of the covered bed perhaps 60 times during storms and timed practice sessions. And when the dozens of future grad students pore over the hours of data we collected, we’re hoping we added to the 13-minute warning.
How To Drive in a Tornado
Tornadoes come in half a dozen formal sizes, measured by the damage they do, sometimes calculated with wind speeds, EF0 to EF5. An EF5 tornado with near 300-mph winds will pick up a 50,000-pound John Deere combine harvester and toss it 100 yards. Smaller EF2 tornadoes, with wind speeds of less than 125 mph, have hit the 13,000-pound Tornado Intercept Vehicle created to film IMAX movies and television shows, and the only damage has been missing instruments and debris-peppered paint.
Our H3T withstood the baseball-hail barrage because of its tiny glass windows and upright windshield. We had only a broadband laptop image from the national Storm Prediction Center, which updates about every five minutes, to guide us down I-80 in the darkness. Sustained northerly wind speeds of 70 mph meant we had to drive with the steering wheel at a 90-degree angle from straight ahead. Worse was that we had to maintain 75 mph to stay ahead of the storm’s core, which produced a tornado one mile from I-80 as we passed. We locked the center differential to keep the front tires from hydroplaning, and within two hours, we’d finally beaten the storm east.
This supercell, which originated in Chugwater, Wyoming, and dropped an EF2 tornado right in front of the VORTEX2 teams, moved into Nebraska and pummeled I-80 with large hail for four hours, forcing the westbound lanes to close. Finally, it dropped 2.5 inches of rain on Omaha, perhaps 400 miles east from where the storm systems originally began.
Best advice: Don’t drive in a tornado.