Avalanche center launches urban forecasting system

Web site plans daily forecasts until April 18

Posted: Tuesday, February 20, 2007

For the next two months, Juneau residents will be able to log onto the nation's first Web site of its kind to check the day's urban avalanche danger.

The site is a demonstration of the only operating urban avalanche forecasting system in the country, said Bill Glude, executive director of the Southeast Alaska Avalanche Center.

Glude and roughly 20 volunteers will monitor two paths on Mount Juneau that threaten the Highlands and White neighborhoods, both just north of downtown.

"I would have liked to have run it earlier in the year when we had so much snow," he said.

Juneau has experienced record snowfall this winter, but Glude said that there have been only two serious avalanche "cycles" this season because of the intervals between heavy snowfalls.

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Of the $45,000 allocated by the Juneau Assembly last fall, $4,000 was set aside to purchase flight time on a helicopter to view conditions from the air.

Besides flights every 10 days, Glude and volunteers will carry out daily visual checks from downtown and from areas along North Douglas Highway.

Most fieldwork, however, is done on skis.

"It is our fastest and safest way of moving around," Glude said.

Field workers also will monitor avalanche danger from Eaglecrest Ski Area, which offers easy access to higher elevations.

While that's not exactly the same as being on Mount Juneau, it does help give a picture of what conditions might be like across Gastineau Channel, Glude said.

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"It gives you some insight. You have to know how those relate to each other," he said.

"Often during a storm I can get some pretty darn useful information. I can see just how much new snow we are getting up there, whether the snow is dry or wet."

Glude said the daily report is a compilation of an assessment of snow conditions and current and projected weather forecasts.

"You can't do an avalanche forecast on snow alone. You have to have a weather report also," he said.

The fieldwork can be particularly grueling.

"It takes a lot of time out there. People tend to think it is glamorous. A lot of volunteers come out for (just) one day," Glude said. The most critical days for forecasts are during storms when temperatures dip far below freezing.

"It is not just all fun. Those ones who stay, they learn a lot about snow."

Snowslides are far from predictable, however.

"Sometimes a few of (the avalanches) just don't run (when we think they might)," Glude said. "There is a fairly high element of chaos in the system, to put it into mathematical terms.

"We may predict avalanches are likely. Even though they didn't happen, that didn't mean they weren't likely."

If the danger level is high for the day, there are several things that Juneau residents can do, but the best precaution is to stay out of the danger zones. The site also has a map of known avalanche chutes.

"If you are living in those areas maybe it would be a good time to go stay with friends or be in safer parts of your house; have an avalanche beacon on," Glude said.

"If we could just reduce the numbers by a few people when an avalanche does occur, we have made a tremendous difference in the outcome."

The possibility of evacuation is low, even in case of extreme danger.

"In Alaska, we'd get nowhere with having some kind of mandatory evacuation. If we were always evacuating, (people would) get tired and think that we were crying wolf," he said.

Glude estimates that periods of high or extreme danger come around just two weeks per winter.

"Our mission really is to identify those times so (people) have an informed choice," he said.

The Web site plans daily forecasts until April 18.

How do I read the advisory?

At the Web site, www.avalanche.org/~seaac, you will see four icons that look like car speedometers.

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The ratings are based on a national scale created by the U.S. Forest Service and modified to accommodate differences between urban and rural forecasts.

The meters include the following:

• The level of avalanche danger: low, moderate, serious or high. If danger is extreme, the arrow will point off the gauge.

• The 24-hour trend on a scale of one to five. One indicates decreasing danger, three same danger and five, increasing danger.

• The probability of an avalanche, ranging from one (unlikely) to five (likely).

• The size of an avalanche, ranging from one (small) to five (large).

Below the meters are several notes on conditions, any additional tips about avalanche safety that might seem appropriate, and an explanation about how to use the advisory.

When should I be worried about an avalanche?

"We really don't expect to see large avalanches until we are at 'high' or 'off the scale,'" said Bill Glude, avalanche expert. The urban-area advisory differs from a backcountry advisory because once a backcountry advisory hits "serious" it is wise to stay clear of dangerous zones.

"For urban residents, at 'serious' you would want to be alert for changes to the weather, but we are generally not worried," Glude said.

What areas is the advisory monitoring?

The advisory applies only to the two paths on Mount Juneau that affect the Highlands and the White neighborhoods.

The advisory will be updated daily at 6:30 a.m., but updates might occur at any time throughout the day.

If weather conditions change, it is advisable to check the site again.

• Brittany Retherford can be reached at brittany.retherford@juneauempire.com or 523-2276.

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