Juneau’s urban forecast for avalanches will be available as heavy snowfall continues to hit Southeast Alaska this weekend.
Juneau’s manager of emergency programs is Tom Mattice. He said he would keep an eye on mountains during the weekend’s avalanche season.
span style=”font weight: 400 In the backcountry of the high mountains there are going to be some big avalanches,” said he. It is not yet likely to make its way into urban areas, but I don’t see it. However, things will change dramatically in the coming days .”
Mattice believes that the combination of the forecast for this weekend and the recent cold snap will create the perfect conditions for avalanches to occur in the high mountain mountains.
span style=”font weight: 400 We’ll be seeing several feet of snow over the course of several days. It’ll be warming up during this time and it will even get some rain towards the end. He said that all of this is trending in the wrong direction.
It is possible that the incoming snow will not bond with the snowpack. This could increase avalanche danger.
He said that we would see an upside-down snowpack, where heavier snow will be placed on lighter snow.
Juneau is at greater risk of urban avalanche than any other U.S. City, as avalanche paths threaten multiple neighborhoods and roads. Mattice provides updates at 8 a.m. every day on the urban avalanche advisory, along with ratings on a scale from 1 to 5. The Saturday update will go live.
It can be difficult to forecast avalanches. Mattice keeps track of the snow accumulation throughout the season and monitors daily weather forecasts. Mattice also regularly visits the field to measure snowpack and look for any weak snow layers.
Mattice’s thoughts are focused on what makes snow layers bond together.
span style=”font weight: 400 It starts with what’s below the mountain tops,” Mattice stated.
Juneau hasn’t had heavy snow this winter. This means that snow anchors well to rough terrain, with rocks, trees, shrubs, and bushes. As snow accumulates, this will change.
span style=”font weight: 400 As we see more snow in the terrain, these things start to get buried and the larger areas that are flat and smooth, the bigger your starting points become.” Mattice stated.
The amount of snow, and not the consistency of the weather, will have a less impact on risk over the course of winter. Even years with a lot of snow can still be quite safe, as long as the snow is falling steadily over the course of the season. This tends to create a stable snowpack in mountains. When snow storms occur during long periods of rain, sun or wind, it can lead to weak layers. This makes the snowpack unstable.
Mattice stated that the city forecasts only urban avalanche risks, but it can also be used as a proxy for those who venture out into the backcountry or on the Flume Trail or Upper Perseverance Trail close to downtown. Backcountry risk will rise when urban avalanche risks are high.
Mattice will keep you informed of any changes in the forecasts. Mattice encourages everyone to keep informed about changes in the weather throughout winter.
He said that span style=”font weight: 400 People have to make their own informed decisions.” There are periods that are very safe. Then you realize that things can change overnight and become very dangerous .”
Mattice encourages anyone who ventures out into the backcountry, to report avalanche observations at the Alaska Coastal Avalanche Center
