Storm Chasing in Tornado Alley

Storm Chasing is a `sport’ which anyone can do – old or young, male or female, athlete or couch potato, and people with disabilities. All you need is a reliable car, a full tank, a camera, a good map, and steady nerves! A little experience would help too - but you have to start sometime.

This was my idea of a fun activity for my visit to the United States during May and June this year. I spent the first few weeks touring many states, giving talks on climate to community and university groups, and most of the remainder was spent in western Oklahoma, USA, right in the middle of `Tornado Alley’ and right at the peak time of year for them. After a lot of research about these `supercell’ storms, I wondered how the real thing would compare with how storms were portrayed in the Hollywood movie, Twister.

My first two chases turned out to be disappointing as the storms failed to develop beyond ordinary thunderstorms. Even the professional chasers from one of the research institutions, with their bright gleaming chase vehicles, gave up in disgust, as I saw them returning to Oklahoma City on Interstate 40 in a neat single-file convoy, just like the `baddies’ in Twister.

But on Friday 24^th May, my third such chase, I met a full-on supercell for the very first time - actually two of them. My eyes and ears for this endeavour was my colleague and friend Jerry Brennan, who from his home in Connecticut was able to monitor real time radar pictures from the Internet and convey the results to me by phone.

On the morning of 24th May, Jerry informed me of an internet report that a promising target area for that day would be Childress, Texas (see radar map downloaded by Jerry, Fig.1), so I drove down there from my temporary base (an old Route-66 motel in Clinton, Oklahoma) only to find lots of ordinary cumulus clouds in the sky stretched out in a fairly narrow band across the sky from north-northeast to south-southwest. This was the so-called `Dry Line’, the breeding ground for supercell thunderstorms where dry air from the south-western desert collides with warm humid air from the Gulf of Mexico. Other storm chasers also arrived in the town, presumably acting on the same information, almost turning the place into a storm chaser convention. This was around 1 pm, and everyone was waiting around for the expected afternoon thunderstorms to develop. I remember wondering what the local people thought with so many storm chasers in town.

We did not have long to wait. One of those harmless-looking cumulus clouds started to get bigger and darker than the rest, the cloud churning and `boiling’ so rapidly that it looked more like a speeded-up movie. Yet this was happening in real time. Within half an hour I could hear faint rumblings of thunder coming from it. Another half an hour and a cup of coffee later, I watched it hover over Childress, growing like some science fiction monster into a full-blown thunderstorm. Hail started falling and lightning was coming from the cloud. Then it started to move rapidly northeast, heading for Oklahoma.

Fig.1 - A radar view from Oklahoma City of the developing group of supercells

Fig.2 - Darkening sky

The chase was on!

I followed it north on US-83, then turned east on US-62 to cross the Red River into Oklahoma, going in as close to the storm as I dared, but not so close as to get hit by the golf-ball sized hailstones (one hit me on the head and it hurt!), or become the target for one of the numerous bolts of lightning which were making random strikes all around the centre of the storm. The precipitation came down in violent torrents, a mix of rain and hail.

Fig.3 - Faint outline of a tornado reaching to the ground

I was rewarded with two rare sights, a tornado barely visible through the gloom of hail and rain, descending at an angle to the ground about a mile away, and a bit later a `downburst’ where part of the storm had become so top-heavy that it collapsed to the ground a mile from me.

Fortunately both events occurred out in the country well away from population. Even in mid-afternoon, the sky was dark, so dark it was black in places, so dark that the automatic flash in my digital camera was firing off every time I took a photo. The cloud base was very low, almost reaching the ground in some places. This was due to the high altitude of the High Plains (thus their name). All this was definitely not like Twister!

Due to inexperience, I parked briefly on a country road (OK-30) north of Hollis, Oklahoma, observing the storm ahead, only to have a bolt of lightning hit the ground a few feet behind me – followed by a loud hissing sound from the instant boiling on the wet ground, This was also followed by a clap of thunder so loud that it felt like a grenade exploding in my rented car.

Fig.4 - A downburst falling (at the right)

Fig.5 - Other Storm Chasers

Startled, I saw the other chasers who were parked near me screech their tyres and speed away from me in the opposite direction. I looked out my side window and saw why – a second supercell had formed behind the first one and had crept up the road un-noticed behind us, growing in power all the time, the same tell-tale rapid `boiling’ of the storm cloud. Both myself and the other chasers had been so preoccupied with the first cell that we were caught out by the unexpected appearance of the second one. It too was dumping large hail and throwing lightning bolts everywhere.

Fig.6 - Under the core

Looking up briefly, I saw the whole dark cloud mass of this second cell rotating a few hundred feet above my head, which meant I was right under the core of a rotating supercell. Rotation is not good, not if you are directly beneath it ! It means a tornado or a downburst could crash down on you from above at any moment. A quick click with the camera and I was out of there like a bat out of Hell, my car following the other chasers south on OK-30 who clearly saw the same danger.

Fig.7 - Mammatus clouds near Hobart, Oklahoma

Once I was a safer distance south of both cells, I watched the storms move rapidly away and disperse in various directions into Oklahoma, the whole Dry Line becoming swept up into a broad mass of thunderstorms. But I was delivered one final reward. Following on the heels of the dispersing storms, I drove into Hobart, Oklahoma (pronounced `Hobert’) and looking up, I saw a spectacular display of high altitude `mammatus’ clouds, only visible in the wake of the most powerful supercells. They hang like soft mammaries (thus their name) beneath the underside of the giant anvil clouds.

Was this a typical day for a storm chaser? Hardly. About 90% of storm chasing seems to be spent waiting, more waiting, drinking lots of coffee, reading `War and Peace’, getting bored and frustrated by the fine weather that others might revel in, but which spells a day of impatient boredom for you. (On two such days, I took an excursion to Roswell, New Mexico, hopefully to have a close encounter with an `alien’). Only when the word gets out that a supercell is forming somewhere, usually on a dry line, does everyone rush for their cars and race across the high wide plains to meet Nature’s most spectacular show.

As to the comparison with Twister, the reality was much different. I chased two more supercells on different days in northern Texas and found the skies are much darker than in the movie, black even, the lightning is all pervasive, not just pretty flashes, but high-energy bolts coming straight down from the low cloud to the ground in rapid succession. The rain and hail is a second major problem as the hailstones are so big that they can smash the windscreen of your car if you are not careful.

Fig.8 - Black sky in mid afternoon

The sheer volume of rain and hail also obscures from sight any tornadoes which may be lurking in the core of the storm. With that black curtain in front of you, it is a considerable risk to go in there looking for a tornado which might or might not be there. In Twister, the characters were chasing tornadoes in bright sunlight and perfect visibility. The reality for the storms I saw is that it is dark, very dark, and the tornado - if there is one – is difficult to see through the curtain of heavy rain and hail. I was lucky to get a glimpse of even one.

I asked several local people in Oklahoma about tornadoes, and was surprised to find that many of them had never actually seen one. When the storm warnings go off, usually with warnings on the radio and TV accompanied by loud wailing sirens, most people seek shelter rather than hang around to get hit by golfball-sized hailstones, electrocuted by the numerous lightning bolts, struck by debris from violent winds, or swept up by a tornado which is often invisible behind a dark wall of rain and hail until it is almost on top of you. That’s why so many people have been killed or injured by them over the years. During one of the storms I chased, near Pampa, Texas, a local resident was struck by lightning.

Would I do it all over again? You bet.