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.