A tornado touches down in downtown Salt Lake City. In a southern Utah national park, a key road is wiped out by a flash flood. Mud loosened by a thunderstorm threatens to cascade into homes in an area burned by a wildfire.
For Utah's 1,207 volunteer weather spotters, such mayhem is a call to arms. Their eyes and measurements provide vital on-the-ground information to augment the radar and sophisticated computer systems used by the National Weather Service's Salt Lake City office.
"We ask our spotters to identify and report events to our office," said Kevin Barjenbruch, a National Weather Service meteorologist who coordinates spotters' efforts, adding that "most of their reports are event-driven. We get extreme events at times. They are not just ordinary day-to-day happenings, but special events."
Some spotters, such as Darwin Woodruff of Taylorsville and Wade Mathews of Tooele, marry their interest in weather with a love of amateur radio. In emergency situations, ham radio operators can serve as valuable eyes and ears on the ground.
"The weather is something that interested me," said Woodruff. "When you can get information into the weather department about where a front is at and what is going on, they can get a better feel and chance at forecasting."
Spotters help professionals such as Barjenbruch fulfill the National Weather Service mission of predicting storms that might pose a risk to lives and property. The agency uses on-the-ground observations to help issue new warnings, cancel existing warnings, extend warnings or send warnings for an adjacent county.
Barjenbruch, who kept a weather journal when growing up on a farm near Leigh, Neb., said scientists love to have as much data as possible.
"Spotters augment our radar data, satellite data and any observation we have," he said. "They ground truth reports, such as the rainfall amount and hail size that is correlated with the radar data we are looking at prior, during and after the weather. â¦ They allow forecasters to have confidence in warning decisions and motivate people to take action to protect lives and property."
Just being interested in weather isn't enough to qualify, however. Spotters must take a class from the National Weather Service to learn observation techniques.
Barjenbruch said no equipment is required of spotters, though many use rain gauges, snow measurement sticks, devices that measure the size of hail or sophisticated automated weather stations that record rainfall, wind speed, wind direction and barometric pressure.
Greg Jackson, who has homes in Duck Creek Village and Cedar City, said he has a portable weather station at each house. But he carries temperature and wind gauges with him.
"They don't have that many spotters in the southern end of the state," he said. "They were happy to have me. I've always had an interest in weather and I follow it down here a lot. Getting good data is a challenge."
Other spotters, such as Matt McDonald of Tooele, serve primarily as observers and use little equipment.
"I like weather," he said. "It is something cool to be involved with. It was an informative class where we learned about different types of clouds, what to look for and how the weather service does watches and warnings."
Mathews, a public information officer for Tooele County's Storm Ready program, has been a spotter since 2003. He took some weather classes in college and, while he didn't choose it as his profession, has always enjoyed watching the weather.
"The most important thing a spotter can have are eyeballs so you can report what you are seeing," he said. "That's what helps the National Weather Service the most. They have the forecasting equipment and radar, but they like the eyes on the ground. In class they teach you how to estimate wind speed by looking at what you are seeing around you. They teach you to look at hailstones and have size comparisons to other things. I have a rain gauge at my home."
Barjenbruch said he has trained observers in flash flood-prone southern Utah. Other spotters proved valuable in areas ravaged by fire earlier in the year.
"Most of our spotters come to us through training organized by county and city emergency managers," he said. "One of the requirements is for [a]â¦ training session that includes weather terminology, weather criteria, thunderstorm development and structure and how to identify weather features.
"We teach what information to report, how to report and ways to get weather information during an event. We teach weather safety as well," Barjenbruch said.