Hail bigger than three quarters of an inch in diameter.

Winds greater than 58 mph.

Tornadoes.

These are the qualifications of a severe storm.

Eric Snodgrass, an instructor for atmospheric sciences, teaches classes year-round and amidst it all he tries to set aside a week at the end of each semester to go storm chasing.

There are right and wrong storms to chase.

The super-cell is the right one, which produces severe weather and tornadoes, Snodgrass said.

As an undergraduate student, Snodgrass often chased storms called squall-lines.

“A squall-line is a big long line of intense precipitation. They are brief and they are not impressive,” Snodgrass said. “The problem is you chase these things and you could get into some nasty winds and get into some hail.”

And hail is something Snodgrass hopes to avoid.

“The thing that scares me the most, again, it’s not the winds. It’s not the tornado, even. It’s not the ominous looking clouds. It’s not the lighting. The one thing that scares me the most when I start storm chasing is the hail, because the hail can be huge.”

According to the National Hazard Statistics Web site, in 2006, hail produced the most property damage throughout the U.S., costing nearly $1.6 million.

Brian Jewett, a research scientist at the University, also chases storms.

“I think one of my first chases we didn’t see a tornado but we saw so much hail that it looked like winter,” Jewett said as he recalled a time he chased storms in Texas.

Jewett was further inspired to study the structures of severe thunderstorms on April 19, 1996, when a tornado outbreak hit southeast Urbana. Before the tornado arrived, several small storms split apart and recombined west of Springfield. This occurrence sparked Jewett’s curiosity about how smaller clusters of storms affect the onset of severe weather.

There are two different ways of storm chasing, and understanding storm structure is important in both of them.

There’s the amateur way. All you need is a camera, cell phone and some sort of way to get Doppler Radar; whether that is by using a laptop with wireless Internet, calling a friend or listening to the radio.

The advanced method involves weather balloons, antennas to record atmospheric data and a radar detector on the back of a semi-truck.

Jewett remembers when weather information was not available on the web and on cell phones. Storm chasers had to visit National Weather Service offices, provided the office was willing to sharing their weather data. When storm chasers arrived on site, they wouldn’t have access to updated weather reports like chasers do now and would have to resort to just instincts and observations.

A storm chaser usually wants to be on the southeast side of a tornado facing the hook-echo in order to get a good view, Snodgrass said. The hook-echo is the result of wind rotation in the thunderstorm and looks like a curved tail at the end on a radar screen.

If a storm chaser gets caught in a bad position the best option would just be to drive away.

“The old guidance was to drive at right-angles to it,” said Jewett, but when in a car one can pretty much just drive 70 mph in the opposite direction. Tornadoes move an average 50-60 mph in their faster season, which is early spring. Throughout May to June they slow down to an average of 20 mph.

Snodgrass recalls a time when he chased in Bethany, Mo.

“There is another aspect of storm chasing that is kind of sobering and that is when you see the damage that it does, and Bethany was pretty much destroyed,” Snodgrass said. However, he still appreciates the beautiful rain bands that wrapped the backside of the storm in sheets of water.

The riskiest move for a storm chaser to pull is “punching the core of the storm,” which means driving through the middle of heavy rains and possible hail in order to get to the east side of the hook-echo. This position provides a view of the tornado unobstructed by the rest of the storm and is also safer for the chaser.

“Nobody’s incredibly calm when you’re out there,” Jewett said. “That’s part of the rush in going.”

Snodgrass knows the trips are not always full of thrills. Most supercell storms occur in the west around Kansas and Oklahoma. Snodgrass’ recent successful storm chase occurred in Lacrosse, Wis., about a 400 mile drive from Champaign. He then drove around I-90 and I-94 to get position on the storm, which he then chased to Green Bay. The trip consisted of an hour and a half of action and a 25 second visual of a tornado.

“So yes, you get really really bored, and it is a very expensive hobby,” Snodgrass said. By the time he returned home he had put over a total of 1000 miles on his car. Luckily, working on cars is his second hobby.

“What happens is a lot of times I’ll take someone new and they won’t ever ask to go again,” Snodgrass said. He explains the gas money and time spent may feel like a waste if the storm becomes a bust and just dissipates.

Glen Romine, a research associate at the University, has gone storm chasing with Jewett.

Romine said once you find a storm it’s exhilarating. He related it to another natural wonder.

“If you’ve ever been on top of a mountain it is just an incredible view,” Romine said, adding that he feels the same energy from a storm when it is present.

On successful chases, the footage and pictures he gathers are always put to good use.

Snodgrass is anxious to bring pieces of his trips into the classroom.

“If I can show you what it looks like on the radar, pictures and in real life, it is more valuable for my students.”

Storm chasing is a lot more popular in Kansas and Oklahoma than around Illinois.

“There’s a lot of non-meteorologists who go actually, and we don’t see it up here so much, but in Oklahoma it’s almost become a state sport,” Jewett said.

One time Jewett chased a tornado in Oklahoma with around 50 cars on the road. He said it gets scary to try and reposition when other cars are in the way creating a small traffic jam.

“There are a few different types of thunderstorms. The one you want to chase is called the super-cell, because, really there’s no reason to go storm chasing unless you want to see a tornado,” Snodgrass said. “That’s the ultimate goal. Can I see something that’s so awesome and powerful that it needs to be observed in its full glory?”