This is the weak tornado Robin scanned in Colorado on May 26, 2010, during VORTEX2. No one reported seeing a tornado.
Spotting a tornado at night is tricky. Seeing twisters wrapped by rain or hidden among hills is tough too. Some tornadoes are just harder to see than others. But can a tornado be invisible? Completely unseen by the human eye? Robin Tanamachi thinks so. And she has proof.
In 2010, VORTEX2’s roving squadron of storm scientists were storm chasing in western Kansas. On May 25, a weak tornado, only an EF-0, formed under a supercell. The teams successfully studied and scanned the twister. Terrific! Once the show in the sky ended, everyone headed over the Colorado border to a hotel outside of Denver.
This is the weak tornado Robin scanned in Colorado on May 26, 2010, during VORTEX2. No one reported seeing a tornado.
The next day, while chasing a nearby storm, the VORTEX2 mobile radars picked up something. The area beneath a supercell looked suspicious. But no one reported seeing a twister.
“One hundred of the best tornado scientists in the world were there watching this storm,” says Robin. It lasted eight minutes. “And all of us went home saying there was no tornado.”
Later on, when Robin took a closer look at the Colorado radar scans, she saw something different. “My radar data shows that there is this feature that looks just like the tornado we saw the day before,” Robin says. The Colorado scans were similar to the Kansas tornado radar scans. “Same duration, same kind of wind speeds, but no funnel cloud.” Had there been a tornado in Colorado, too?
This is the weak tornado Robin scanned in Kansas on May 25, 2010, during VORTEX2. Everyone agreed it was a tornado.
Robin decided to investigate the question: If it looks like a tornado, lasts as long as a tornado, and behaves like a tornado, but only on radar, is it still a tornado?
Robin is a research meteorologist. Research scientists gain knowledge through experiments and observations. Research starts with an idea or explanation for something—a hypothesis. “You design an experiment to test that hypothesis, get your results, and make your conclusions,” explains Robin.
Robin’s hypothesis? The Colorado tornado was not seen because there wasn’t enough moisture in the air to create the foggy part of a funnel cloud.
Sometimes a tornado underneath a supercell is obvious—like this one. But twisters aren’t always so easy to see.
Robin tested her hypothesis by analyzing the VORTEX2 data. She compared the Kansas and Colorado storms, studying how they were alike and different.
Robin’s conclusion? “It was real,” says Robin. There had been a tornado in Colorado, too. “It was definitely there.” Neither tornado did any damage and no one got hurt. Does it matter if it was a tornado or not?
“As a scientist, I care, “ she wrote on her blog. Figuring out what is and what isn’t a tornado is important. Just because no one saw it doesn’t mean it didn’t happen. What humans see is very different from what radar can detect. That’s why it’s the go-to tool for tornado-tracking meteorologists.
On May 4, 2007, a half-mile-wide (.8 km) EF-5 wedge tornado plowed through the town of Greensburg, Kansas. It changed the lives of all 1,500 residents. “I was one of them,” Megan Gardiner wrote.
The teenager was working at her afterschool restaurant job that evening. The weather had been stormy, but Megan still hoped to meet up with friends later. After going outside to empty the trash around nine thirty p.m. she changed her mind. The lightning was like nothing she’d ever seen. Megan headed home instead.
She joined her family, their dogs, and some neighbors in the home’s basement. Megan remembers the local TV weather reporter saying a tornado was headed for Greensburg. Predicted impact was 9:52 p.m. Her phone read 9:47.
Greensburg residents search and sort through what’s left of their town.
We have five minutes, Megan remembered thinking. By now emergency sirens were wailing, winds were howling, and hail as big as golf balls slammed into the house. Then the power went out, leaving everyone in the dark.
“All of a sudden my ears started to pop really bad,” remembered Megan. “I mean, this was worse than going in a plane or diving deep under the water.” She wrapped herself in a blanket and got ready to crouch down and cover her head. And then it was quiet. Spooky quiet. Until the windows exploded.
This is what Greensburg, Kansas, looked like after an EF-5 wedge tornado a half mile (.8 km) wide scoured the town in 2007.
“I heard the walls tearing and ripping off into pieces,” said Megan. “Then something hit my left shoulder.” Chunks of the home were falling onto everyone. And then it was over. It took nearly a half hour to climb out of the basement in the rain and dark.
“We looked back and there was nothing left,” wrote Megan. Just piles and piles of rubble. Nearly a thousand homes and buildings were destroyed in Greensburg, Kansas, that night. Eleven people lost their lives in the tornado. Sixty more were injured.
Megan and her family were okay, though the high school senior had nightmares for weeks. That’s why she decided to write about what happened. It helped. “But I get very paranoid when a storm comes,” admitted Megan.
After a month of hauling away debris from the Greensburg tornado, the town has few remaining buildings.
Radar is a technology that uses radio waves to see, or detect, objects from a distance. Radar can reveal everything from fighter jets and flocks of birds to valleys at the bottom of the sea.
Weather radar detects precipitation. It picks up all but the tiniest raindrops, hailstones, and snowflakes. Radar does more than locate where this precipitation is falling. It tells you how hard it’s coming down, how fast it’s moving, and from which direction.
Radar can’t see wind directly. Molecules of moving air are too tiny for radar to pick up. But radar can detect whatever the wind moves around—rain, snow, dust, etc. Meteorologists use radar to figure out wind speed and direction by tracking how fast and where precipitation is being moved by air.
This mobile radar truck from VORTEX2 aims its antenna at a dropping funnel cloud.
A thunderhead cloud spreads into an anvil shape as it hits the tropopause.
How does weather radar work?
A magnetron creates microwaves, the same kind of electromagnetic energy that heats up lunch leftovers.
The radar unit’s transmitter sends out quick pulses of microwaves via the antenna .
The microwaves pass through air, but not precipitation. Some of the microwaves hitting water drops scatter in all directions.
Some of the rain-scattered or snow-scattered microwaves bounce back to the dish-shaped radar. A receiver detects the returned microwaves.
These steps happen fast and continually. The radar emits a pulse, listens for returned signals and records them, and immediately emits another pulse. The entire cycle takes only a millisecond. Fast computers crunch the collected signals instantly, making radar a tool that meteorologists use as weather happens.
Microwaves, like all kinds of electromagnetic energy, travel at the speed of light (186,000 miles [300,000 km] per second). Radar determines the distance to a storm by tracking the time it takes for a pulse’s echo to bounce back. Knowing the distance along with the direction the transmitter was pointing in tells the radar the exact location of the storm. The strength or intensity of the signal returning to the radar depends on what it bounced off of. Echoes from a rain-dumping thunderstorm are more intense than those from snow flurries. And hailstones bounce back a different kind of signal than sleet.
These radar antennas can’t be aimed, so they emit a wider low-resolution beam.
Computers process all this information into a weather radar map. Like the kind used in TV weather forecasts, the map shows where the storm is and uses colors to identify the kinds and strengths of precipitation it’s making.
Most weather radar used in the twenty-first century is called Doppler. This means it not only tracks when echoing signals return but also measures the changes in their frequency. Think of the sound of an ambulance driving past you. Once it’s moving away, the siren changes and sounds lower. It changed sound frequency to your ears. Doppler radar uses the changes in microwave frequency to map wind speeds and directions and show which way and how fast a storm is moving.
The cone-shaped antenna of this mobile radar is movable. Meteorologists point it toward the section of sky they want to scan.
One of the 158 National Weather Service high-resolution Doppler weather radars across the United States.
What does a tornado look like on radar? Here are two radar patterns scientists look for: hook echo (below) and debris ball (above).
“My job is to come up with an hypothesis about how thunderstorms behave,” explained Robin. “And then use instruments like radars and precipitation sensors to test those hypotheses.”
Radar is Robin’s specialty. “Radar radiates microwave pulses out into the atmosphere,” she says. “They backscatter off of precipitation particles and whatever else is out there and come back to us.”
Weather radar can locate, measure, and track weather ingredients in the atmosphere. “It’s like a Swiss army knife,” says Robin. “I’m really interested in opening the hood on severe thunderstorms and figuring out what’s going on inside of them. Radar is an incredibly valuable tool for doing that.”
Studying radar data to figure out whether what happened in Colorado was or wasn’t a tornado is a perfect example. Radar helps dissect and measure a tornado’s powerful mix of winds, rain, and energy to find the patterns that lead to tornadoes.
That’s where the storm chasing comes in. It’s how Robin collects the high-resolution radar scans. “We can see very small scales and detailed structures inside of the tornadoes,” Robin says. But driving a radar truck toward supercells is only part of it. “Doing the field work only takes about maybe a month out of every year.”
What’s she doing the other eleven months? “I’m sitting on my butt in front of the computer, analyzing the data, visualizing it, slicing and dicing it, and doing statistical analyses on it,” says Robin. She uses computers to visualize the tornadoes and the storms that made them.
Scientists have tornado-making computer software. “We can make an artificial storm on the computer,” says Robin. You enter in the temperatures and humidity of a chunk of pretend atmosphere and hit go. “It’ll grow and rise up, form condensation [growing into a cloud], and become a storm based on equations.” Weather by math!
Robin points out a line of storms on a radar map.
A computer storm that makes a virtual tornado is interesting. But it’s not real. That’s where radar scans collected during storms help out. Robin loads her radar measurements into the computer. Then the software goes to work stitching the data together into a timeline of how the storm grew and made a twister. “We can use that to recreate the storm and test hypotheses about how it came into being,” says Robin. Computer models learn from real-life examples, adding the knowledge to their program and getting smarter.
Robin can test the tornado computer model against the real thing, too. Like with what happened during the Greensburg, Kansas, tornado. Robin’s team was storm chasing nearby on May 4, 2007, until their radar truck got a flat tire. While getting the tire replaced in Greensburg, a supercell thunderstorm started growing nearby. Might as well scan it, they decided.
“It was growing and growing and ended up dropping a wall cloud,” remembers Robin. The supercell dropped a first tornado and then another. All eyes were glued to the radar screen when the big one happened. “It started producing this gigantic tornado signature.”
Later, Robin put all the Greensburg radar data into the computer model and asked it to predict the tornado’s path. It was dead on. The computer mapped out the same track the devastating tornado had taken through the town. “When I withheld the data from the mobile radar, the track and storm behavior wasn’t nearly as accurate.”
All that screen time and number crunching is the experiment that answers Robin’s question about tornadoes or tornado behavior. “Once I come to a conclusion that’s pretty clear, I can publish it in a scientific journal,” says Robin. This is how the rest of the world learns about scientific discoveries. Robin writes a technical paper that describes the experiment, methods, and her conclusions. Then experts review it.
“It takes a really long time to get from collecting data in the field to actually publishing a paper on it—up to five years sometimes,” says Robin. Good science takes time. Scientists want to make sure it’s right before putting their name on it.
Robin and Dan teach meteorology at Purdue University.
During VORTEX2 Robin wrote up some of the tornado chases for the project’s website. She liked it, so she decided to start her own blog. “I wanted people to have a glimpse inside the life of a research meteorologist,” Robin says. And that includes storm chasing. “I would produce a blog post for every chase, explaining where I went and what I saw and I’d link to the videos or pictures of what was going on.”
Why did she name her blog Tornatrix? She’d been trying to think up a name for both a blog and a Twitter handle. (Storm chasers are big on handles and call signs. It’s a ham radio thing.) “I was kind of playing around with tornado woman, twister-ess, that kind of thing,” remembers Robin.
“And then Tornatrix popped into my head!” The word ending -trix means woman, like how aviatrix is an old-fashioned name for a female pilot. Perfect!
Robin’s Tornatrix blog has been quiet the past few years. Time for blogging is hard to find these days between her job and being a mom to two young sons. “But I do want to get back to it,” says Robin. Her last blog post said goodbye to Oklahoma after thirteen years. She listed all the things she’d miss, including big tornadoes!
Robin, Dan, and their boys, Dan Jr. and baby Paul. It’s a busy life!
It was time to move on. Robin and Dan had jobs waiting at Purdue University in Indiana. Robin’s radar skills would find new adventures there, including becoming a member of a new generation of VORTEX scientists. This one wasn’t on the Great Plains. Its target? Dixie Alley.