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GOODLAND, Kan. - They stayed safe, and weren't sorry. During five intense hours weaving in and around powerful supercell thunderstorms over eastern Colorado on Tuesday, the 12-member Southwest Virginia storm-chasing team twice bailed out from prime positions to see possible developing tornadoes as other storm hazards made the locations dangerous. Twice, the team was within easy visual range of rapidly rotating wall clouds, or lowered masses below the thunderstorm base, that appeared ready to drop a tornado. Each time, team leader Dave Carroll decided to retreat quickly because of fast-approaching high winds, rain and hail. "We were the chase team in position to intercept a tornado," Carroll said, referring in particular to the second of the two situations, south of Yuma, Colo. There, the team drove into visual range of a spinning wall cloud that had been detected as a developing tornado by National Weather Service radar, but had little time as a wall of wind, rain and hail they had escaped from in a storm to the north was about to overtake them. "We were getting squeezed out. Our only bailout route was west," said Carroll, a Pulaski County High School meteorology teacher and veteran storm chaser. "If we had gone east on that road, it would have been ugly; we'd probably come out without windshields, or something like that." No one on the chase team, primarily composed of New River Valley high school and college students, expressed any disappointment at not seeing a confirmable tornado on the last day of chasing in the Great Plains before heading back to Virginia. "I saw what I came to see," said Jeremy Swink, a Virginia Tech junior. "I saw a part of the country I hadn't seen before, and I saw some pretty cool storm structure." "It's not all about the tornado," said Ethan Knocke, a Virginia Tech graduate student and one of the team's lead forecasters. "We got where we needed to be, and that was a big enough success in itself." If Tuesday's chase had been a fishing expedition, it would have been one in which the boat was filled to the brim with colorful fish, lacking only the "big one." The chasers saw at least seven wall clouds in three supercell thunderstorms in the nearly treeless high plains of Yuma, Kit Carson and Cheyenne counties of eastern Colorado. Just north of the town of Yuma, the chasers had a rare opportunity to observe a developing wall cloud at close range. The team had stopped there upon observing two other wall clouds in the area, one of which was extremely low to the west, appearing almost to graze the ground. While stopped alongside a farmer's field, another mass began lowering within a mile or two to their north. Fed by gusty southeast surface wind flowing toward it, the new structure developed into a spiral formation, and then developed into almost a doughnut shape with an aquamarine-glowing hole. That was where a "rear flank downdraft" was occurring, Carroll said, or a blast of wind descending from the back of the storm. Dust kicked up under the cloud was probably the result of strong downdraft winds rather than a tornado, he said, though he added later that the mass appeared ready to drop a tornado. Other dust could be seen in the distance being pulled toward the structure. But a few minutes later, with wind and hail approaching from the southwest, the chasers got back into the vans and raced south. They stopped a couple of times to observe a shelf cloud, or a broad mass being pushed by high winds, moving toward them, but made the stops brief to stay ahead of it. Turning a bit east from the southward escape, they observed another wall cloud shortly after the tornado warning had been issued by the weather service, but had to escape west as the same "gust front" to the north was about to overtake them. Later in the day, the chasers pursued a wall cloud on a gravel road south of Interstate 70. They encountered about five minutes of pea-size hail - the only hail they saw the entire day - and eventually got blocked from the well-rounded wall cloud by a sheet of rain ahead of them. With the discrete supercell storms fusing into a line, the chasers finally called it a day about 7:30 p.m. Mountain Daylight time, about five hours after they had begun moving toward the storm at Yuma. With the only risk of severe weather a slight one much farther to the south, the team would forgo an extra day of chasing on Wednesday and begin heading back to Virginia, expecting to arrive today. In eight days of chasing on the Plains, the team had three highly active days, three "bust" days of no activity, and two travel days devoted to positioning for the next day. Team members did not see an obviously recognizable tornado, though it is possible that some features observed on each of the three chase days could have been tornadoes. Contrary to popular belief, tornadoes do not always have a visible funnel from cloud to ground, but can be a rotation on the ground with an invisible extension to the cloud above. Twister or not, everyone agreed it had been worth the time and effort. "I can't believe how much I learned," said Jacob Carley, a freshman meteorology student at the University of North Carolina-Asheville. "This is not a fluff trip at all," Carroll said. "It's hard-core applied science."This is the last in a series of stories by weather columnist Kevin Myatt as he joined a storm-chasing Pulaski County teacher and his crew of students. Kevin Myatt talks about what it's like to be in a monster storm and what Midwesterners think about the storm chasers that crisscross the region. Dyou have a question about tornadoes? Send an e-mail to Kevin at kevin.myatt@roanoke.com, and he may post an answer online. |
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