Tornado Alley is centered on Texas, Oklahoma, Arkansas, and Missouri, where warm, moist air from the Gulf hits cool dry air from the northwest. There's an elevation gradient involved, too, with the cool air rolling down the long slope from the Rockies to the Gulf and the warm air sliding up it. Often the cool air overshoots the warm. Now you've got a big pile of cool air sitting above an unhappy layer of warm air. They want to trade places. When they do, they usually end up spiraling past each other. Bingo: mesocyclone.
During April, May, and June, there is usually one big storm a week, and it usually spawns tornadoes. It's a staggering thing to watch. People dog on the Great Plains states for not having any scenery. There's plenty of scenery. It's just up in the air.
The best storms start in the afternoon. Those big cumulonimbus clouds start piling up and piling up. You can see it happen from 20, 30, sometimes even 50 miles away, if it's a clear day. They pile up until they hit the stratosphere, and the high winds up there blow the top of the cloud out into the familiar anvil shape. At this point the storm is 10-20 miles tall and has a radius to match. It is boiling with energy. Lightning starts firing. From the top of the cloud to the base. From the base to the top. From one part of the cloud to another at the same altitude--big snakes of lightning miles long. From the ground to the cloud, and the cloud to the ground.
By now the storm is influencing the atmosphere for dozens of miles around. If you're watching all of this happen from a lawn chair in your back yard, it gets dark and cold and the wind picks up, even if you're not under the cloud (if you were under the cloud, you probably wouldn't still be outside watching). You shiver, take a big pull off your bottle of beer, and say a silent thanks that you're not one of the poor bastards stuck underneath that juggernaut.
If you are underneath the storm, it still may not be raining. It's like a bully has you pinned against the lockers, arm pulled back to smash your face in, and he's just holding it and letting you suffer. 'Cuz you know it's coming. You may go out in the yard and check the color of the clouds. Wall clouds, the kind that drop tornadoes, are the strangest shade of greenish black. Kinda like the fluid that runs out of a week-dead carcass, if you have any experience in that area. When you see clouds that color, it just looks wrong.
Whether you're under the storm or not, you probably have the TV on, and if you're outside you're running in now and then to check it, and vice versa. The National Severe Storms Lab is in Norman, Oklahoma. The local NBC, ABC, and CBS affiliates each have their own Doppler radar, and they upgrade them regularly. The storms usually move together in a line* from west to east, so you can tell from the radar picture whether you're going to get a little rain or an asskicking.
*Forgot to mention that above. Thunderheads often travel in packs. If you're upwind of them, sometimes you can see four or five of them strung out to the horizon.
If it's a bad cluster of storms, you can forget about watching normal broadcast television. Either your show will be interrupted every five minutes for a tornado update, or the station will have switched over to full-time coverage.
The biggest and best storm I ever watched the was the May 3, 1999 cluster that spawned the F5 in Oklahoma City. This was while Vicki and I were living on the north edge of Norman, about 20 miles south of OKC. The storm came out of the west in the late afternoon. Our duplex faced south, so we took chair across the street and sat on the sidewalk and watched. It was unbelievable. We could see the mesocyclone. The whole base of the storm, probably 30 or 40 miles across, was slowly rotating, a bit faster than the minute hand of a clock on continuous sweep. We couldn't see the whole thing, of course, just the edge. The sun was going down, and the whole back side of the storm was painted in sunset colors.
When it got dark, we went inside to follow things on the tube. It was crazy. The middle of the state was completely red with tornado warnings. Torandoes were on the ground everywhere. A monster tornado had touched down near Chickasha and was headed for OKC. Chickasha (chick-a-shay) is about an hour southwest of Norma; we went there once in a while to pig out at Jake's Barbeque. The meteorologists were warning people in south Oklahoma City: get below ground. If you don't have a cellar, get out of the house and go to a public shelter. Those warnings saved thousands of lives.
That tornado was the strongest ever measured. Previously, the fastest wind anyone had ever clocked on Earth was 286 mph near Red Rock, Oklahoma. The peak windspeed of the May 3 tornado was 318 mph. It ripped a trail across the south end of Oklahoma City a mile wide. It crossed I-35 right at the overpass for the Shields Boulevard exit. From the top of the overpass, you could see the path of the tornado like God's own wrecking ball. There was a swath a half mile wide where nothing stood. No trees, no stumps, no telephone poles, no reinforced interior walls...nothing. If you were above ground in that zone, you were dead, period. For a quarter mile on either side of that, it looked like someone had stuck a giant mixer into the ground and just churned everything into mush. All of the debris you usually associate with tornadoes--collapsed buildings, chunks of buildings, buildings that had briefly been airborne, uprooted trees, smashed cars, telephone poles, and everything else--was laying a big jumble. Where the tornado went over the overpass, it had stripped the topsoil off the ground and left the grass dangling by exposed roots.
All of this stretched to the horizon in both directions. For two weeks, you had a half hour delay if you went up through OKC on I-35, because people from Texas and Kansas were rubbernecking at the top of the overpass. I didn't blame them; when I got my turn at the top of the hill, I rubbernecked, too.
That single tornado wrecked more than 10,000 buildings, caused 1.1 billion dollars in damage, and killed 36 people. Considering that 2300 homes and almost 500 apartments simply ceased to exist, that's an amazingly low death toll. Thank God for Doppler radar. And it wasn't alone. In the 72 hours starting on May 3, Oklahoma was hit by 66 tornadoes. They did another half billion dollars of damage and killed another ten people.
I later heard that a meteorology grad student at OU had gotten some footage of the big tornado on his camcorder and sold it for $10,000.
Oh, a couple of misperceptions to clear up. I lived in Oklahoma and frequently visited Texas and Kansas until I was 26. In all of that time, I never heard anyone who was from the plains call a tornado a 'twister'. It's greenhorn Hollywood wannabe bullshit. Also, if you watch the movie Twister, you get the impression that tornadoes are easily visible against the sunlit fields. Usually if you're close enough to see one, you're under an immense black cloud 30 miles wide, it's raining pitchforks, and you can't see your hand in front of your face. Which is why footage of an F5 tornado would be worth ten grand. The tornadoes you see on the Weather Channel are usually the little F1s and F2s lurking around the edge of the storm, not the Finger Of God monsters that drop from the center (F1s and F2s can still fuck up your program, though).
I have more tornado stories, but they'll have to wait for another time. Work is calling.
All of this has come back to me because Jarrod just got back from Oklahoma, and he snapped this kickass picture of a lightning strike near his mom's house. In his words:
"One of the highlights of the trip was the first night in Oklahoma. A big storm blew in and I got the camera and tripod out and got the lightning picture I've been trying for YEARS to capture! I was out there, using the 'bulb' setting on the camera - meaning as long as I held down the trigger, the shutter stays open. Every time there was a decent flash, I'd release and start again. So, the wind kicks up, it's probably 50 miles an hour, and it finally starts to rain a little bit, so I decide it's time to pack it in. So I'm about to release, when
I released, grabbed the tripod and covered my ears. It couldn't have been more than a half mile away. I felt the rumble in my chest. I ran inside, hoping, PRAYING that I'd gotten it. I like to think it's a sweet shot!"
Thanks to Jarrod for the loan of the photo.