Issued: Tue, Feb 21, 2017 at 10AM

Expires: Fri, Feb 24, 2017

Above 2,500ft Moderate

1,500 to 2,500ft Moderate

Below 1,500ft Moderate

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

Problem #1: Wind Slab

Distribution: Widespread, all aspects and elevations. Last week’s storm snow is settled and well bonded in most places. But there is still some weakness near the bottom of the recent snow, around 60-90cm deep. Also, there are still density interfaces and wind slabs within the storm snow that may act as a weak layer and cause an avalanche in steep areas. Generally higher, colder, wind-loaded slopes will be the most prone to human-triggered slides.

There is a fair bit of variability out there above treeline as well. Some areas are well-bonded with thick slabs and little in the way of weak layers. Other areas have a noticeable hollow sound/feel beneath surface wind slabs. Avoid these areas.

Problem #2: Deep Slab

Distribution: Isolated, on wind-blown slopes with thin snowpack less than 1m thick. Generally around ridgelines, and anywhere rocks are exposed or thinly buried. All aspects. Elevations above 3000ft. In the Pass zone, there are extensive weak facets at the ground in any areas of thin snowpack. We haven’t observed avalanches on this layer yet, but there remain trigger points in areas of thin snowpack or rocks. If you were to trigger a slide on this layer, it would be a deep, wide, hard slab avalanche with deadly consequences. This is a low-probability high-danger situation that is very difficult to manage, so it’s best to exercise caution. Be very careful to avoid rocky trigger points and thin areas. Stick to slopes with a deeper, more uniform snowpack.

Recent Avalanche Activity

The last observed avalanche activity was during the last storm cycle Feb 11-15th. There was a natural avalanche cycle within the new storm snow, with widespread D2-D3 slides on all aspects. These were dry slabs above 4000ft, and some nasty wet slabs below that level. A few large avalanches occurred, with crowns up to 2m tall. Some slides hit the valley floors and lower runouts.

Recent Weather

It’s going to be a beautiful week. With mostly clear skies, light-moderate winds, and mountain temperatures 10-25F with lots of sun. The next chance of significant snow will come Saturday.

Temperatures have been well below freezing, and winds light since our last storm on the 15th.

Feb 11-15th brought a pretty exceptional storm cycle. It started with 10-15″ of cold, weak, low-density snow, with another 10-15″ of heavy, wet snow above. This led to poor bonding within the new snow. We then had a significant rain-on-snow event on the 13th, with up to 2″ of rain falling below 4000ft. Rain reached up to 5000ft for a brief period. The cycle finished up with a nice shot of cold air and nice, fluffy snow 12-18″ on top of the saturated wet slop below. Temperatures dropped to 10-20F on the 16th as the storm cleared out.

Additional Info & Media

This is an important time to practice good group management skills and risk-reduction. This means keeping your group spread out while traveling in avalanche terrain. Ride one-at-a-time in any areas of risk, and only group up in safe zones well out of harms way. Evaluate each slope carefully, have an escape route, and a plan for what to do if an avalanche occurs. Always make sure every rider has a beacon, shovel, and probe, and knows how to use them.

Posted in Chilkat Pass Forecasts.
Erik Stevens

Forecaster: Erik Stevens