Gazing up at the mushroom cloud coming directly towards us, it looks to me like the world is about to end. A thick, black swirling mass of noise and destruction is heading our way and in about three minutes' time, all hell will break loose. Right on the spot where I'm standing.
In the time it takes you to read this sentence, the air temperature drops 10 degrees. Tumbleweeds and dust fly past my ears as the meteorological monster sucks anything that isn't nailed to the ground up into its belly, like an angry weather god. We now have approximately two minutes to get the hell out.
According to weather reports, the approaching supercell storm is armed to the teeth with hailstones the size of golf balls. Anything caught in its path risks serious injury-or worse. For most sane individuals, getting caught in a storm like this would constitute extreme bad luck. However, for the group of tornado chasers I'm here with, it's "fun."
That's easy for them to say, safely ensconced in two tons of Chevy minivan. It would take a large explosive device to blow that thing off the road. Meanwhile, I'm at the wheel of a bright red Mini Cooper S complete with novelty bonnet stripes. Fashionable it may be, but will it save me from hurricane-force winds and deadly hail? This is the question at the forefront of my mind, as I wrap my sweaty palms around the leather steering wheel and prepare to take off like a stabbed rat. If this thing catches up with me, it'll be more than my pride that gets damaged.
I met my new storm-chasing chums in Colorado, at the start of a six-day tour. All week I've been accompanying them across Middle America as we search for the ultimate prize: a tornado. Surprisingly, they're not the bleached-blonde adrenaline junkies you might expect. Indeed, most of them are middle-aged and reassuringly sensible, like Colorado resident Jane Reller, who is celebrating her 50th birthday while on the tour. "I've been fascinated by big storms since watching The Wizard of Oz as a kid," she declares.
However, one person who I suspect of being a closet mentalist is 68-year-old Glen Nix. Having flown fighter planes in Vietnam, he doesn't look like the type who gets easily scared. "I've flown straight through monsoons in combat situations, but I'm interested to see what they look like from the ground," he says nonchalantly, standing before me in his requisite Ray-Ban Aviators and military-style crew cut.
The leader of our gang is Roger Hill, a qualified meteorologist and self-confessed storm chasing addict. Following a career in the Air Force, he turned a childhood fascination into a thriving business by becoming a guide and partner in Silver Lining Tours, an Oklahoma-based storm chasing company that runs trips throughout the Midwest from May to July.
During this period every year, the area of Middle America known as Tornado Alley-including the states of Kansas, Nebraska, Colorado and the Dakotas-comes under attack from hundreds of storms, which sweep across the region on a daily basis. Many of them inflict huge damage on whatever gets in their path. However, they're not to be confused with the devastating hurricanes that caused so much destruction in Florida and New Orleans last year.
A hurricane is characterized by ultra-high-speed winds that circulate around a center of low pressure. On a photograph, this looks like a giant comma-shaped cloud, with a point (eye) in the middle. Meanwhile, a supercell is a giant thunderstorm-around 15 miles across-containing a huge updraft of wind. This then forms an anvil-shaped cloud that bears unsettling similarities to the mushroom cloud generated by a nuclear explosion. When these up-flowing winds spiral out of control, tornadoes can form. Not every supercell produces tornadoes, but nearly all of them contain massive hailstones, along with torrential rain, deafening thunder and spectacular lightning. Witnessing one is, without doubt, an awe-inspiring experience. Getting caught in the center of one is terrifying.
Each day of the tour begins with Roger briefing us as to what we can expect to see. Using the latest weather monitoring software, he is able to work out which storm systems are most likely to produce a tornado. All we have to do is "intercept" it, overtake it and outrun it.
This is where the Mini comes in. Small, speedy and incredibly nimble, it seems like the perfect vehicle for outwitting Mother Nature.
However, it's far from ideal for the huge road trips involved before reaching the storms. On any given day, these could be up to 700 miles away, necessitating an epic drive across the flat, featureless land of the Great Plains.
Over the course of the week we've visited no less than seven states covering around 3,500 miles in the process. The bulk of our days are spent cruising along ruler-straight roads in sixth gear, trying not to nod off. Occasionally I find myself roused from my reverie by the nauseating smell of cooking fat, as we enter yet another single-street town containing the same array of nasty fast-food joints.
Once we catch site of a storm, though, these long periods of ennui are immediately forgotten. The first one I witness is in Wyoming, on the opening afternoon. Having driven around 400 miles from Colorado, we'd navigated our way into a perfect vantage point to witness a huge supercell that Roger had been eyeing up all afternoon. Not content with sitting there and watching it from afar, he leads us down a dusty track where we can get up close and personal. Just in front of us, a writhing mass of inky cloud thrashes away angrily, accompanied by the low rumbling sound of hailstones rattling around inside the storm's core.
The key to safe storm chasing is knowing when to quit. While the rest of us gawp, point and take as many pictures as our cameras allow, Roger keeps a beady eye on exactly how close the storm is getting. As soon as he judges it time to leave, there's no dilly-dallying; even a 30-second delay could mean the difference between a great photo and grave danger. This has been the safety procedure that's kept us out of harm's way throughout the week-until now, in Montana...
With Roger speeding off into the distance to get ahead of the approaching storm, I shift up through the Mini's gears in a bid to stay with him. Unfortunately, I find myself stuck behind a slow-moving semi, losing valuable seconds and, more importantly, losing sight of Roger in the lead van.
Finally I'm able to overtake; the race is on to catch up with the group-and avoid being engulfed by the ferocious black cloud that's growing ever larger in my rear-view mirror. The supercharger whizzes away frantically as I accelerate up to 100 mph-but it's all too late.
Visibility drops to zero and apocalypse erupts all around me. I pull over to the side of the road, as the Mini begins to get pelted by hailstones, bigger than any I've seen before, causing the windscreen to flex worryingly as they bounce off it.
This is nothing compared to what comes next. Seconds later, my panic-stricken voice is drowned out by the terrifying crash of solid ice rocks punching against metal. It sounds like I'm surrounded by an angry mob attacking the Mini with sledgehammers. Suddenly the side window caves in, showering me with glass. Hail now cascades into the car and I curl up into a ball, desperately attempting to shelter my face. This is no longer an adventure. Frankly, I'm terrified.
It seems to take a lifetime for the storm's core to pass directly overhead, yet the whole thing only lasts around three minutes. I manage to relocate Roger and the rest of the group and we limp to the nearest town to lick our wounds.
The damage to the Mini is shocking. Every single panel is dented, bits of plastic trim have been ripped off and patches of paint are stripped down to the bare metal. This was a very lucky escape.
After sealing up the smashed window with cardboard, we make our way on to our overnight stop, in the town of Glendive, eastern Montana. En route, we pass felled trees and overturned trucks lying in the storm's wake, testament to its awesome and awful power.
That night, while we're sound asleep in our beds, the same storm goes on to produce the elusive tornado we've spent all week searching for. It wrecks nearby farm buildings, brings down power lines and causes chaos to the local community.
Speaking from experience, I'm glad we missed it.