Howitzer
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Hi, I'm Dave Thurlow from the Mount Washington Observatory. Today on The Weather Notebook, correspondent Becky Rumsey watches as road crews take aim on an avalanche.

"Just outside of Silverton, CO on Highway 550, a crew in bright orange coveralls is setting up an army green cannon. It's a Howitzer and the Colorado Department of Transportation is using it to bring down avalanches before they slide on their own and hurt someone."

Andy Gleason: "The Howitzer's new for us this year and we're really happy to have the artillery, because its a more accurate shot. It has a longer range so we can get farther up into the starting zones. Normally we use the helicopter to drop bombs out of it. But when the weather's bad, we can't fly."

"Andy Gleason is an avalanche forecaster who monitors conditions on Highway 550. Its one of the most hazardous mountain roads in America because its on the receiving end of more than 200 avalanche chutes in a region known for unstable snow."

Andy Gleason: "Our snowpack right now has a lot of depth hoar, or a weak layer, some people call it sugar snow, at the bottom of the snowpack which will persist throughout the year. Its very typical of this area, of a continental snow climate and we've got a good slab layer on top. So, that's really the key ingredient for an avalanche."

"It's a good shot. The avalanche cracks 3-4 feet deep. As it slides, it takes out all the layers down to the ground. But the debris stops before it hits the road. Just what the avalanche control crew wants."

That was Becky Rumsey in Southwestern Colorado. Funding for the show is provided by the National Science Foundation and by Subaru.