LOCAL STORM CHASERS AREN'T DAREDEVILS

When Dave Carroll lists his biggest fears about chasing storms,the top one on his list has nothing to do with storms.

"Traffic," he says.

Then comes heavy rain, hail and lightning. "The actual tornado isway down the list," he said.

Carroll, a Roanoke native and Blacksburg resident who teachesmeteorology classes at Pulaski County High School, has been chasingstorms in the Midwest since the 1980s. Several times in the lastdecade, he has taken a small group of local high school and collegestudents with him.

Carroll will be leading a group of eight students - four fromVirginia Tech, four from Pulaski County High School - on a weeklongstorm-chasing trip beginning Friday.

The storm chasing Carroll and his group do is not daredevil stuff.It's serious science and a public service. The students look at eachday's weather data and, as a group, decide where to go that day tohave the best chance of intercepting severe thunderstorms. Also,Carroll's crew members act as storm spotters, helping local officialsand the National Weather Service track severe weather.

The group will be traveling in two vans equipped with wirelessInternet, two-way radios between the vehicles, CB radios, NOAAweather radio and police scanners.

Last year, Carroll recalls, the chasers were following a storm inTexas when they heard on a radio that a tornado had been spotted init. An official asked over the radio if there was another spotternear the storm to confirm the sighting. Once Carroll and his fellowchasers got past a grove of trees - "the only trees in Texas,"somebody can be heard joking on a videotape playback of the chase -they were able to report back and confirm the sighting.

"Five seconds later, the weather radio goes off and there's atornado warning. Ten seconds later, we hear the sirens go off in thetown down the road from us," he said, referring to the tornadowarning sirens many Midwestern towns use.

Last year's chase was one of Carroll's most successful, with onetornado spotted and photographed and thunderstorms pursued every dayof the trip. Most years, there are some days when there are no stormsto chase, and the group takes in tourist destinations like CarlsbadCaverns instead. While there are almost always thunderstormssomewhere to go after, tornado encounters are rare, and there'salways a slight chance of a dull, stormless week. All part of theadventure, chasers say.

"If you catch a big fish every time you go fishing, then nobodywould ever want to go," said Seth Price, a senior material sciencesand engineering major at Virginia Tech who is responsible for thegroup's radio equipment.

Price has set up a way for you to follow the group's progress: Atwww.n3mra.com, the group's position will be pinpointed on a radarmap, showing how close it is getting to storms. We'll set up a linkon roanoke.com to help you follow the group's chase.

One hail of a storm

Sometimes, the chaser doesn't go to the storms, but the stormscome to him. Carroll said that returning from Richmond on Sunday, heencountered two severe hailstorms: one in Bedford County nearMontvale, the other as he approached his home in Blacksburg.

A number of you, particularly in Montgomery and Bedford counties,experienced severe weather Sunday. Because of thunderstorms' slowmovement, some places received hail for a long period of time,causing enough to accumulate to cover the ground in some areas.

The thunderstorms that developed over the area Sunday were "pulse-type" thunderstorms. These storms form rapidly from updrafts and thencollapse even more rapidly. When they collapse, they bring anenormous push of wind, heavy rain and hail. The updrafts were causedby afternoon heating and enhanced by the area's mountainousgeography. When the sun went down, the heat source for the updraftswas turned off, and the storms soon died.

David Wert, chief meteorologist at the National Weather Service inBlacksburg, said that dry air aloft in the storm caused cold air todip unusually low as moist downdrafts were pulled through it. Thisenabled hail to form much lower to the ground than would normally beexpected in moderately intense May thunderstorms, and as a result,much more of it was able to reach the ground.

The "heat dome" high-pressure area I talked about last week isstill over us and will give us a summerlike, mostly dry week. Butwhile this big tent high in the atmosphere will keep a lot of the bigbirds from swooping down on us, a few flies and mosquitoes will beable to get in under it. With this kind of warmth, any small bug inthe atmosphere can kick off a few "pulse-type" storms.