Earth Notes: The NWS Storm Spotter Program
Doppler radar is a crucial tool for spotting severe weather, but it doesn’t tell the whole story. When a thunderstorm is far away, the radar can typically only see the upper portions of it.
To issue accurate severe weather warnings, the National Weather Service also needs to know what’s going on in the storm’s lower portion—especially at ground level.
Every spring, the National Weather Service’s Warning Coordination Meteorologist, Tony Merriman, recruits volunteers to report severe weather from their locality across northern Arizona.
The Storm Spotting program has been running nationally for several decades. In northern Arizona, Merriman organizes the training workshops, which lasts about an hour and a half. Potential volunteers are taught what kinds of clouds and severe weather to look for—and how to report them.
Report-worthy conditions include hail one inch or more in diameter, strong winds exceeding sixty miles an hour, flash flooding, as well as tornadoes and funnel clouds.
A local volunteer provided valuable real-time information shortly after last year’s Goodwin fire in Yavapai County, when a rainstorm over the fire scar triggered flash flooding. The storm spotter gave the weather service regular updates on both the rain and the movement of the flood wave—information that was used to issue an important flashflood warning for the town of Mayer.