Winter weirdness is in full bloom across the nation, but few places rival the bizarre weather that recently hit northern Alabama -- thundersnow.
Snowstorms that trigger lightning are rare. Of the roughly 10,000,000 cloud-to-ground lightning flashes observed over the continental United States each year, about 0.1 percent to 0.01 percent are associated with snow, says Walter Petersen, atmospheric physicist with NASA's Marshall Space Flight Center in Huntsville, Ala.
"Rare events tend to be the things that get us. We don't predict them. A big lightning flash could have a very large impact in a hurry," Peterson told Discovery News.
By fortuitous circumstance, Alabama's thundersnow occurred over a sophisticated lightning mapping station in Huntsville, close to where scientists had quickly assembled an armada of radars and other instruments to collect data during the approaching snowstorm. They weren't expecting lightning.
"We're all kind of weather geeks here so we're paying attention to the weather a few days out. A significant weather event here is a few inches of snow. We generally lean to suspecting that the forecasts are a little off -- the models are being a little aggressive about how much snow we're going to get. This one, though, the models were really very consistent," Petersen said.
Petersen oversees a NASA-backed team that deploys to various locations around the world to collect data about precipitation, information that will be used to interpret observations from a new network of Earth-monitoring satellites. The Huntsville snowstorm was a chance to add to that information bank, without tapping the travel budget.
Early results from the impromptu campaign show that the lightning traveled for 30 to 50 miles along layers in low clouds before touching ground, a finding that has implications for safeguarding power grids, among other concerns.
"A lot of times people are killed by bolts from the blue, or they think they're a good distance away," Petersen said.
Scientists also found that more than 50 percent of the lightning flashes initiated off of a radio tower just east of Huntsville. They are working to flesh out the contributing roles of snow, wind and supercold water on the development and spread of the lightning.
"We've the got the ability to look at how the snowflakes originate, grow and fall, and relate that to where the lighting flashes tend to propagate through the clouds that produce the snow. Not many events are caught like that," Petersen said.
Atmospheric physicist Kevin Knupp, with the University of Alabama in Huntsville, suspects that gravity waves, which are up and down ripples in the atmosphere somewhat like waves on a beach, are the invisible hands behind thundersnow, interacting with supercold water so that electric charges can build up, leading to lightning.
"Mother Nature treated us well," Knupp told Discovery News. "We were in the right place and things came together for us to see a number of interesting things."
Findings collected during the Jan. 9 storm are being analyzed, with publication to follow.
© 2012 Discovery Channel