Wanted: Weather spotters
Severe weather workshop focuses
By GREG STAHL
Express Staff Writer
Since the 1940s, the National
Weather Service has been nurturing a civilian weather spotter program to
help the agency more accurately alert the public at large when hazardous
weather is imminent.
On Wednesday, May 5, National
Weather Service Warning Coordination Meteorologist Vernon Preston hosted
a workshop in Bellevue to train a half dozen potential weather spotters.
"Itís a volunteer network, and all
it takes is a 30-second phone call," he said. "Anybody can be a weather
spotter, whether they get formal training or not. Weather spotters hold
up the entire structure."
Hereís how it works: When severe
weather occurs, weather spotters telephone the National Weather Service
to relay on-the-ground observations that meteorologists then plug into
computer models or logbooks. Sometimes weather spotter observations are
used to alert people who are down-wind from an oncoming storm about the
severe-weather-related deaths are on the decline, and he credited the
weather spotter program for that trend.
There are some 600 amateur weather
spotters in Southern Idaho. There are about 120,000 throughout the U.S.
"Itís just real-time weather
information," Preston said. "Itís just a great way to share in the
community, and hopefully some folks will be saved from disaster."
Preston, who worked chasing severe
storms on the Great Plains before moving to Idaho, gave an informative
and interesting two-hour presentation on severe weather. He covered
floods, snowstorms, thunderstorms and tornadoesóall hazardous weather
that can and do occur in Idaho.
His class, by design, was an
introduction to severe weather in the Intermountain West.
The United States has the most
severe weather of anywhere in the world, Preston said. Idaho, compared
with many states, is relatively mild. Each year, Idaho has about six
tornadoes and a handful of severe hail or thunderstorm events.
By far, Idahoís most prevalent
dangerous weather is caused by winter storms.
But it takes more than a
thunderstorm or snowstrom to generate severe weather. Wind is not
considered severe until is reaches 60 mph gusts or is sustained at 40
mph. Snowstorms are considered severe if they pile higher than 6 inches
on the plain or higher than 9 inches in the mountains within a 24-hour
"But when you throw wind in to the
equation, any snow can be dangerous," Preston said.
Ice storms are considered severe
when they accumulate to a quarter of an inch or deeper.
The lionís share of Prestonís
presentation focused on thunderstorms and the ingredients that go into
forming one. He explained updrafts, downdrafts, overshooting tops,
rain-free cloud bases, wall clouds and microbursts.
Though Preston explained a lot of
the reasons weather becomes severe, he admitted that there are things
science canít yet explain.
"We just donít know certain
reasons why storms become severe," he said.
Weather spotter basics
In Southern Idaho, weather
spotters should call (800) 877-1937 when they discover severe weather.
Here are some rules of thumb when gauging whether weather is severe or
- Tornadoes (location and
- Rainfall amounts (over 1 inch).
- Damaging winds (estimate
- Low visibility (less than one
- Freezing rain.
- Snow totals (more than 1 inch
- Hail (dime size or larger).