Storm chasers watched with horror as the deadly tornado bore down on Moore, Okla. Their radar scans were showing the violent storm kicking up giant clusters of debris.
Ryan Snoddon, a CBC meteorologist from St. John's, was in the area on his first trip as a storm chaser in Oklahoma's tornado alley.
He told CBC Radio's The Current that he was hoping to film a tornado touching down in an empty field. Instead, he saw what he calls the "worst-case scenario" — a tornado packing 320 km/h winds slamming into the town of Moore.
- Watch this explanation of how a tornado forms
- CBC meteorologist describes tornado devastation
- Before and after: See what the twister did
The storm chasers who had been following the storm alerted weather authorities in the area about the tornado, which provided about 15 minutes warning for those nearby to brace themselves.
In hyper-aware Oklahoma — which was hit by a massive tornado in May 1999 — many got the message.
"Storm chasers are the ones that are right there, that can see that tornado touch down immediately … they're the eyes, they're the ones that can tell the weatherman on TV 'this thing is coming,'" said Snoddon.
So what technology are storm chasers using? And, can you use similar information to keep yourself safe from extreme weather?
A storm chaser's toolkit
Many storm chasers rely on advanced equipment, including Doppler on Wheels — essentially a fleet of trucks run by the Colorado-based Centre for Severe Weather Research mounted with radar systems that can visualize the size and movement of a storm from a close distance.
Some chasers also use specialized weather balloons called radiosondes to get a better picture of severe weather.
In the U.S., the National Severe Storms Laboratory, a wing of the National Oceanic and Atmospheric Administration (NOAA), is currently testing what it calls "phased-array" radar, which it says scans the sky six times faster than the current Doppler systems.
But while this new technology is helping storm chasers get better pictures of tornados, the challenge of figuring out exactly when these storms will touch ground remains.
"The science is still evolving on these things," said Snoddon. "There's still so much to learn."
Still, Geoff Coulson, a warning preparedness meteorologist with Environment Canada, said that while many storm chasers are amateurs with cameras, he's been "really impressed" with some self-taught chasers and what they can contribute to a developing situation.
"There's a lot of information online," Coulson says.
In Ontario, Environment Canada has trained some 4,000 storm watchers as part of its CanWarn system, and there are thousands more in the Prairie regions.
The CanWarn storm watchers keep an eye out for temperature extremes and thunderstorms, which help Environment Canada improve the accuracy of its weather warnings.
A weather watcher's best friend, Coulson said, is a weather radio, which distributes a stream of weather data from Environment Canada and the NOAA.
The radio works, Coulson said, like "a smoke alarm for weather."
Many of these specialty radios — available online or at many electronics stores — will emit a piecing tone when dangerous weather is approaching. While that may sound like more weather information than you'd ever want, the radios can be put in standby mode, so you only hear them when bad weather is on the horizon.
Smartphone key to weather safety
But none of this matters if people don't take advantage of all this technology to check the weather. "Any thunderstorm poses a threat," Coulson said, adding heavy rain and lightning can strike quickly.
"I just think in our society it's a good idea to check the weather conditions."
Coulson suggests getting in the habit of checking the forecast and relevant weather watches once in the morning and again in the afternoon, when thunderstorms are likely to swell up during the spring and summer months.
Your best bet for getting this information? Your smartphone. Many apps can use your location settings to alert you to severe weather in your area, and radar images can always be found on the Environment Canada site.
If you're out, Coulson said, a scan of the radar can give you an idea of how long you have to seek shelter before a heavy rainfall.
The NOAA is currently testing a system that sends text messages to anyone in an area with dangerous weather conditions, Coulson said, and he's hoping Environment Canada will do something similar in the future.
Ontario town watches weather closer since tornado
In Goderich, Ont., where an F3 tornado tore through the town in 2011, killing one and injuring dozens, there's lots of talk about the Moore tornado.
"I feel sick," Mayor Delbert Shewfelt said. "It shakes you up."
Shewfelt says when the skies darken above the town, he always asks his staff: "Are you ready if we need to go?"
Shewfelt said that, weather-wise, the day of the tornado posed no immediate concerns. "You would have never suspected it … it was such a beautiful day," he said. Then, just before 4 p.m., the town was given a five-minute warning that a tornado was bearing down on them.
The tornado was the strongest to hit Ontario in 15 years. Its winds tore the roofs from historic buildings and churches, uprooted trees and witnesses described cars being thrown like toys.
Today, Shewfelt said, people keep a close eye on the weather, and he encourages each household to have an emergency plan ready.
"I think they get uptight," he says of his fellow citizens. "The weather seems to get wilder and wilder all the time."