(MONEY Magazine) – I'm sitting in the back of a battered, cluttered van parked at a North Dakota truck stop, playing cards with someone I met a week earlier. We both have the punchy, dazed look of people who've spent too much time on the road lately. Suddenly, a guy appears in the van's doorway and shouts, "Get ready! We're leaving!" As people hurry into the van and someone does a quick head count, I put the cards away and ask where we're headed. "Toward the Montana border," I'm told. "Dew points there are up to 62. Let's go, let's go!"

This is a storm-chaser tour, a relatively new kind of travel option. It entails flying to a central point--Oklahoma City, in my case--piling into a van with a bunch of fellow severe-weather enthusiasts, and spending a week or two driving around in search of hail, lightning and, especially, tornadoes. Twisters can be destructive, but most of them take place in rural areas and end up hurting no one. And more than half of the world's twisters occur in the United States, primarily in the Great Plains (also known as Tornado Alley), which is where the tours tend to focus. But there's no fixed itinerary--basically, you go wherever the weather is and worry about dinner and lodging after the storm's over. Onboard computers provide up-to-the-minute forecasting data to the tour guides, allowing them to pinpoint when and where severe weather is likely to occur, as well as the safest vantage points. There are no guarantees, but the possibility of witnessing a twister keeps the anticipation level high, even on slow days. It's sort of like whale watching, except nobody gets seasick.

And tornadoes aren't the only things to see. On Day Two of my June tour, we drove through a spectacular hailstorm in the Nebraska panhandle. Mothball- and golfball-size hailstones pinged and ponged off our group's pair of vans, denting the vehicles' exteriors and cracking the windshield of the one I was in. There was so much hail that it actually piled up in drifts on the highway, temporarily making summer look like winter. A few days later we spent about 40 minutes watching a magnificent lightning storm play across the skies of northeastern Wyoming--one of the most amazing things I've ever seen. And on several occasions we looked on as massive, majestic thunderstorms coalesced in the skies ahead of us.

Storm chasing apparently appeals to a wide demographic. The other eight tourgoers in my group, whose ages ranged from 14 to 50, included a lawyer, a graphic designer, a Baptist minister, two high school students and two secretaries, one of whom came all the way from England. The male/ female split was right down the middle. There were two father/son teams; everyone else traveled solo. Some of the participants were serious weather geeks, rattling off weather jargon and important tornado dates every chance they got; others, like myself, were less fanatical and just thought seeing a twister would be, y'know, really cool. Fortunately, our meteorologist guides did a good job of tailoring their explanations to fit everyone's interest level.

In some ways, a storm-chaser tour is much like any other road trip--the small towns are charming, the open highway is alternately exhilarating and numbing, and by the third day you get really sick of eating potato chips in the car. But in many other ways, storm chasing is a unique travel experience. It's waking up to a sunny morning and disgustedly thinking, "Oh, geez, not again." It's memorizing when the "Storm Watch" segment runs on the Weather Channel. It's keeping your eye on the clouds instead of the countryside as you drive through the heartland. It's an endless stream of such tornado terminology as supercells, cyclonic rotation, wall cloud and punching the core.

It also entails driving--a lot of driving on our tour, which averaged nearly 500 miles a day. We also had repeated instances of rushing someplace and then waiting an hour or two for a storm to develop. All of which is to say that it paid to bring along some diversions--books, a portable CD player and a deck of cards, in my case, although some of the hard-core weather hobbyists had lightning detectors and other meteorological gadgetry on hand. During a two-day period when there was no severe weather at all, more serious time-killing was necessary, so we visited Mount Rushmore and Wyoming's Devil's Tower.

Then finally, on Day Eight, the jackpot. We were driving through eastern Montana, maneuvering to observe a developing storm. A baseball-size hailstone put another crack in our windshield as we turned south. A few miles later, we got out and watched as the skies churned all around us. And then we saw it: a tornado looming in the east. Our guides hurried us back into the vans, consulted their maps, found a dirt road leading east and raced to a vantage point about two miles from the twister, where we all got out and stood slack-jawed, muttering infinite variations on, "I can't believe I'm seeing this." As we fumbled with our cameras, a second tornado briefly touched down, then quickly dissipated. The whole situation veered from surreal to tremendously exciting to terrifying and back again.

A few minutes later, it was over. The storm gave way to a blazing sunset as we happily drove on. The frustration and crankiness that some of us (myself included) had started exhibiting after more than a week on the road gave way to a collective feeling of euphoria, as we discovered that even a few minutes spent watching a tornado more than makes up for days' worth of lesser pursuits. Soon we were celebrating over a steak dinner--the traditional meal after a successful tornado chase--and toasting our good luck. We'd seen a genuine twister--two genuine twisters!--and lived to tell the tale.

Award-winning travel writer Paul Lukas didn't see anything the one time he went whale watching.