Tracking Tornadoes As They Travel
Wednesday’s tornadic supercell storms that killed upwards of 280 people in a wind-driven rampage across the Midwestern United States is the first of its caliber to have been forecasted and monitored through its progression with such first-hand accounts and eyes-in-the-sky intensity.
Reed Timmer and the team of Discovery Channel Storm Chasers monitored the developing storms, filming at least four tornadoes in the process. Their priority for that day – as was the case for veteran storm watchers across the region – was to keep local authorities apprised of the path of destruction these twisters were taking in an effort to save lives.
I caught Reed on the phone to find out what it had been like:
“It was a crazy tornado outbreak. I’ve never chased something of this magnitude in my 13 years of storm chasing. There were 20 or 30 supercells all with violent tornadoes on the ground and it seemed like if there were a thundershower it would have a deadly tornado underneath it. And at that point we really had to prioritize calling in reports for the warning process to keep people safe in the path of these storms,” he said.
The video below shows the thundershowers as they spun their way across the states:
From the ground level these white puffy thunderstorms are as dark as night. These weren’t skinny twisters but mile-wide wedge tornadoes as Reed called them:
“A wedge tornado is definitely one of the most dangerous and deadliest of tornadoes. It’s a really wide tornado – a wedge is defined as wider than it is tall and the reason they are more damaging is because you are inside that tornado that much longer experiencing those tornadic winds. And all the tornadoes we saw yesterday were wedges,” he said.
The cool winds from the west and north that blended with the warm winds from the east and south created the perfect conditions for wind shear — that difference in wind speed, height, and direction — to bring on an attack.
“The tornadoes had a really intense roar, like a jet engine or a waterfall, and I was really afraid of these tornadoes and I’ve been close to them and haven’t really felt that feeling up until now,” Reed said.
Meteorologist Harold Brooks of the National Severe Storms Laboratory in Norman, Okla., reported in the Washington Post that conditions have been ripe in recent weeks for just such a catastrophe:
Cold air aloft blows in from the Rocky Mountains, meeting the low-level, warm, moist air moving northward from the Gulf of Mexico. If the cold fronts are strong enough they’ll suppress tornado formation. But if they’re a bit weaker than that, the lethal combination results: Air at ground level is moving in a different direction from the air higher up, and the rotational energy spawns twisters.
NASA officials explained that the added combination of the two fronts were cut n half by a fierce jet stream on April 27th providing the catalyst for the storms to strike that day.
One wedge tornado spun down in Mississippi, traveled through Alabama, cut into northern Georgia and finally expired in North Carolina. Below are high resolution radar images as the tornado hit Tuscaloosa, Alabama – you can see the telltale hook in the image on the right:
The National Weather Service reported 164 tornadoes struck on April 27.
“It’s some of the worst devastation I’ve ever seen,” Reed said. “And seeing these things up-close and first-hand I’ve never seen such violent motion.”
The Washington Post also reported that the storms shut-down the three nuclear reactors at the Brown’s Ferry power plant about 30 miles west of Huntsville, Ala.
The plant is of a similar design to the severely damaged Fukushima Daiichi power plant in Japan. But unlike Fukushima, when Brown’s Ferry lost primary power, the plant’s diesel generators kicked in as designed to keep the reactors cool, said Barbara Martocci, a spokeswoman for the Tennessee Valley Authority, which operates the 3,274-megawatt facility.
If these storms are shutting down nuclear power plants turning over mobile homes, how does Reed and the storm chasers stay safe? “The Dominator, which is our armored vehicle that we use to drive into tornadoes to record measurements, can withstand winds of up to 170 mph. Anything above that would be a little bit scary. Yesterday we were able to get into the outer circulation of several tornadoes but they were just too strong to safely intersect, at least with Dominator 1. We’re about to upgrade to Dominator 2 here in a week which is designed to withstand the stronger wind speeds that were in those violent tornadoes yesterday,” he explained.
“But yesterday our main goal was to call-in reports and to help out with the warning process because we knew it was potentially a deadly tornado outbreak,” he added.
“Yesterday the National Weather Service and storm prediction center and local media as well as the network of storm chasers all worked really well together to issue tornado warning with really advanced warning lead times. Many of these communities had 30-45 minutes of lead time as the tornado was approaching and they did a really great job. But when you have a tornado out break of this magnitude it’s almost inevitable that you’re going to have loss of life and property and all we can do is work as hard as we can to get the word out and really respect tornadoes and know that they are one of the most powerful natural forces on the planet and they can be deadly.”
IMAGE 1: Still from the NASA animation showing the ingredients for severe weather: a relatively stable mass of cold air — visible as a swirl of more-or-less continuous clouds — rotates in the north along the top of the image while moist air pushes north and west from the Atlantic and Gulf of Mexico. The collision of air masses is amplified by the jet stream, which blew north and east between the two air masses on April 27. Surface winds blowing from the south and east and the jet stream blowing in from the west set up powerful smaller-scale circulations that generated lines of intense thunderstorms. (Credit: NASA and NOAA’s GOES satellite)
IMAGE 2: High resolution radar images of Tuscaloosa courtesy of Heidi Farrar.