Welcome To 'Thundersnow'

Sometimes in the middle of a Midwestern snowstorm, thunder growls and lightning sends dull flashes among the clouds.

A University of Missouri researcher has received a $460,000 grant from the National Science Foundation to find out when and why.

Missouri scientist Patrick Market said for the past four years he's been looking into a phenomenon known as "thundersnow," an apparently rare event that some researchers believe foreshadows an intense snowstorm with heavy accumulation.

Part of his five-year study, which began in July, will try to determine whether thundersnow is rare or just doesn't get reported much.

"One of the questions I'd like to answer precisely is how rare it is," Market said. "Some of it may actually go undetected."

A thundersnow storm Jan. 17, 1994, in Louisville, Ky., dropped about 2 feet of snow, Market said. The center of the storm — a narrow band that contained thunder and lightning — went directly over Louisville, where the biggest accumulation was recorded.

A year later, in January 1995, the same happened in Columbia, Mo., he said. Thundersnow was reported over the city, where the harshest part of the storm hit.

"The kicker here is that the lines of snow were pretty narrow," Market said. "If you took the same band of snowfall 20 miles north of Louisville, or bump the one that fell on Columbia over a little so it affected Sedalia instead, it becomes more of a footnote and doesn't grab as much attention."

Thundersnow is more likely to happen around the Great Lakes because of instability caused by the "lake effect," Market said. However, the study he is concentrating more on non-lake effect thundersnow that occurs in a loose arc across the central U.S.

States where thundersnow is most frequently reported are Missouri, Kansas, Nebraska, Iowa, Colorado, Minnesota, Wisconsin, Oklahoma and into northern Texas, Market said.

A priority of the study will be to find ways to forecast thundersnow. Market and a team of students will make about three or four road trips each winter to chase major snowstorms in search of the elusive thundersnow.

Greg Koch, a meteorologist with the National Weather Service in Pleasant Hill, Mo., said forecasting thundersnow would greatly help meteorologists understand where the biggest accumulations might hit.

"Thundersnow oftentimes is very small-scale phenomena which can lead to wide variations in snow amounts in very small area," Koch said.

Market is trying to enlist the help of anyone with Internet access who witnesses lightning in a winter snowstorm. He has set up a Web site where people can fill out a form and write what they remember.

The next step, he said, would be to look at what causes thundersnow, such as updrafts similar to those found in summer storms.