A massive tornado headed toward Greensburg, long after sunset May 4.
Radars available to the National Weather Service only a few years ago would have been able to detect rotation in the thunderstorm, but not the tornado itself.
But recent advances allowed the Dodge City weather service forecaster on duty to see not only that had a tornado developed, but also that it might be as large as the tornado that hit Oklahoma City in 1999 -- perhaps the strongest ever recorded.
He issued the first "tornado emergency" in the history of the Dodge City office and only the second issued in the United States.
Residents of Greensburg had at least 20 minutes to seek shelter from the 1.7-mile-wide tornado, which damaged or destroyed 95 percent of the town.
The tornado killed nine people in Greensburg. Other tornadoes from the same supercell killed two other people later that night.
The death toll is a testimony to what radar technology offers now, meteorologists said.
"Half the town could have died -- it was that bad of damage," Tim Burke, a meteorologist with the weather service office in Dodge City, said of the community of about 1,400.
"This was not just half a building gone, or part of a building gone, or a wall gone. This was blowing through and taking everything with it."
The new technology and effective warnings likely saved at least 200 lives in Greensburg, said Mike Smith, founder and president of WeatherData, a private forecasting service based in Wichita.
The best comparison to Greensburg, Smith said, is the Udall tornado of May 25, 1955 -- the deadliest in Kansas history. About 15 percent of Udall's residents -- 77 people -- were killed when a huge tornado struck just after 10:30 p.m. Another five people were killed outside of town.
The Greensburg tornado was more than twice that size, he said.
Weather service and television meteorologists "did a magnificent job" recognizing the danger and warning the public, said Smith, whose warning for that storm saved a Union Pacific train from being derailed.
The early, effective warnings were possible because improved radar technology gave forecasters a clearer, quicker picture of what the thunderstorm was doing, said Larry Ruthi, meteorologist-in-charge in Dodge City.
The technology can measure stronger winds rotating inside a supercell thunderstorm, Ruthi said. It also reduces how long it takes to complete a full scan of the atmosphere by more than half, to about four minutes.
Supercell thunderstorms can form in a half-hour or less and produce one tornado after another -- as they did both May 4 and May 5 in western and central Kansas.
The advancements are a significant improvement over what was in use when the F5 tornado struck in Oklahoma and an F4 struck Haysville and Wichita on May 3, 1999, said Brad Ketcham, a meteorologist with the Wichita branch of the weather service.
They're "a gargantuan leap," he added, from what was in use the last time an F5 struck Kansas: April 26, 1991, when a tornado tore through Haysville, Wichita and Andover, killing 17 people.
With radar at that time, "you could never get velocity data, which is so critical," said Ken Cook, another weather service meteorologist based in Wichita.
People still important
The new technology won't make storm spotters and storm chasers obsolete, forecasters say, because they still depend on "ground truth" to confirm what radar is indicating.
"The chase community and spotters out there are an extremely vital link in this process," Ruthi said.
In fact, storm chasers were able to confirm a wedge tornado was on the ground several miles southwest of Greensburg well before it hit. That gave the warnings a stronger sense of urgency, meteorologists said.
Yet even as this stronger, faster Doppler radar is showing what it can do, technology now being tested could dramatically affect radar's capabilities in the next few years.
Dual-polarization and phased-array radars promise to expand what will be available to meteorologists in the not-too-distant future.
The dual-polarization radar should dramatically improve hail size detection, Ketcham said, and the phased-array radar appears capable of providing full scans of the atmosphere about every minute.
Those will help meteorologists monitor the evolution of storms much more closely, he said.