Storm Chasers Motivated by Quest for "Perfect Data Set"

Herb Stein
University of Oklahoma
May 29, 2001
Tornado season on the Southern Plains generally runs from April into
June, peaking during late May. Some years there are few tornadoes. Yet
we're interested in using our Doppler On Wheels radar trucks (DOWs) to
document as many tornadoes as we can, providing data that will help us
acquire a better understanding of this powerful phenomenon of nature.

To track down tornadoes, we have to travel widely during periods of severe storm weather patterns. This often means driving hundreds of miles a day, for many days in a row. Still, we generally intercept only one tornado for every ten outings, as tornadoes are truly rare events.

People know they have the passion for this work if they're able to endure day after day of fruitless chases and still wake the next morning with enthusiasm to continue the mission. So far, 2001 has been one of the fruitless years.

During the first half of the 2001 season we made three road trips, logging more than 2000 miles. All we have to show for our efforts, however, are two minor sets of tornado data, much frustration, and some interesting stories.

The first road trip was a four-day journey in West Texas and parts of Oklahoma. Day 1 found us seven hours away from home on the track of some anemic storms. Ironically, we collected what may be the best record of continuous data that we've ever acquired in our entire career of tracking with radar trucks.

On the Trail

The storm we intercepted was south of Lubbock, Texas. It was severe, but a very slow mover, advancing only five miles in an hour. We positioned our two radar trucks on different sides of the storm to gather data from different points.

The storm looked interesting on radar for a while, but did not grow into a tornado. Our observations were not a failure, however. We must study storms that don't lead to tornadoes along with those that do, so we can learn more about how tornadoes form.

A problem of this particular slow-moving storm was that it dumped huge amounts of rain over the flat terrain of West Texas. As night came, we made our way to Lubbock to find a hotel, but it was difficult to find roads that were not submerged. At one point while driving cautiously down a small rural road, our world momentarily disappeared when a torrent of muddy water splashed onto our windshield and obscured everything. A river of water flowed across the roadway for about a quarter of a mile.

The next day brought nothing more severe than showers and general thunderstorms in Northwest Texas.

On Day 3, we moved on to Southwest Oklahoma, chasing a line of storms that built as evening approached. We positioned ourselves at the northern cell, which, because it was isolated, was the likeliest place for a tornado to develop. The other cells were arranged in a line, which meant they would compete for the warm, moist low-level air that fuels a storm, thus limiting the storm's severity.

The storm in the northern cell began looking anemic as the new line of storms cut off its supply of warm, moist air. With little activity registering on our radar, we shifted to the southern edge of the line of storms, about 50 miles away. Then, to our frustration, the storm we had just left produced, in a last gasp, a brief and very weak tornado as it struggled along.

We were close enough to Norman, Oklahoma, that we were able to spend the night at home.

Promise Deflated

The following day brought greater success. We began by driving a few hours to North Texas, where we waited for storms to develop. As they did, we had a choice of tracking storms that were occurring back in Oklahoma or new ones developing in north central Texas, our original target area.

As we watched the storms evolve, the one in Oklahoma appeared to be more mature and had features that suggested it was more likely to produce tornadoes. We headed for its southernmost cell, just outside Oklahoma.

As we approached, it increasingly had the appearance of leading to a tornado. We positioned our radar trucks to monitor the storm as it passed by.

Bull's-eye! A tornado formed about four miles to our west and approached slowly. It looked like a thin, gray elephant trunk as it struggled again and again to touch the ground. Wisps of debris leaped into the air as it plowed through trees.

Unfortunately for our research efforts, the tornado did not have much gusto. It died after about six minutes, without having grown substantially.

After the tornado died, we continued following the storm because it appeared to have the potential to produce another tornado. But the storm gradually lost its punch and collapsed as it pushed cold, stable air ahead of itself, which cut off its source of energy: the warm, moist inflow of air.

The day was over, but not the season. It is still early, and we still hold out hopes of getting that perfect data set.

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