New station to signal avalanche danger

HATCHER PASS — As the first major snow of the season has backcountry sports on the minds of many, a new weather station atop Marmot Ridge is aimed at informing winter enthusiasts of avalanche danger.

The station relays temperature, barometric pressure, relative humidity and wind speed and direction from its site at 4,500 feet, said Dan Amyot, the chief ranger for the local district of Alaska State Parks. The numbers are reported every hour at http://www.cnfaic.org/wx/wx_marmot.php.

“People can go online and access the information the weather station gathers over the course of each hour. They can determine what has been occurring at the Hatcher Pass area at the higher elevations,” Amyot said.

This is a huge improvement over the existing station down in the bowl of Independence Mine. That location gathers snow depth and moisture content, but it tells people nothing of what happens higher up where many hikers, skiers and snowmachiners recreate, he said.

However, a quick glance at the data shows this is not an avalanche forecasting system. The website does not give the probability of avalanches based on the current conditions, and some basic knowledge is required for interpretation.

What the information shows is how the weather conditions have changed over the past few days. As any avalanche safety course teaches, the period during and 24 hours after a dramatic change in weather is the most likely to experience avalanches, Amyot said.

“What the data the station collects is, during and following that event, what direction was the wind blowing, how high were the winds blowing, … were the temperatures warm at the beginning of the storm, or warm at the end of the storm,” Amyot said.

While the intricacies of avalanche forecasting are too many to go into outside of a classroom, Amyot did offer a few tips. If warm weather comes after a cold spell, this means wet snow will be unstable on top of dry snow. After a big wind storm, avoid the leeward slopes, or even the side slopes, as the wind-driven snow is inherently unstable, he said.

“(Storms) create this stress versus strength balance in the snowpack. When the stress exceeds the strength is when you see avalanches,” Amyot said. “During or 24 hours or more following a snow or wind event, the danger is very high.”

But, he warned, even avoiding these periods of instability does not guarantee backcountry travelers will miss all avalanches.

“If people are going to play in the mountains, take an avalanche safety class. There is a price tag to it and the equipment, … but how does that equate to your life?” Amyot said.

The station was installed by the Friends of the Chugach National Forest Avalanche Information Center, and paid for through donations, small grants and volunteerism, said the center’s director Carl Skustad.

The group’s mission is to increase avalanche awareness throughout Southcenteral Alaska. There are other such weather stations in the Turnagain Pass and Girdwood areas, he said. This is the first in Hatcher Pass.

“This area is an area that needs some help. There is very little in the way of avalanche awareness,” Skustad said.

Contact Todd L. Disher at todd.disher@frontiersman.com or 352-2252.