Avalanche Danger Update

After six days of sunny skies and generally light winds, weather capable of increasing avalanche danger in the greater Anchorage area Western Chugach Mountains returns today.

While storms impacting Southcentral Alaska this weekend will have more of an impact on areas closer to Prince William Sound like Portage and the Eastern Kenai Peninsula (e.g. Turnagain Pass), downslope (rain shadow) winds will impact the greater Anchorage area Western Chugach from Girdwood to the Knik. While the wind-driven increase in avalanche danger will be the primary effect, accumulating snow is possible in the mountains (especially further east and deeper in).

Since last week’s storms that deposited a few to several inches of new snow in the greater Anchorage area Western Chugach, wind had yet to have much of an effect on it until today. Thus, there’s still ample loose snow available for transport into potentially dangerous wind slabs. Wind slab development will be aided further by any trickle of new snow that accompanies increasing winds this weekend.

As the snowpack is still thin, potentially dangerous wind loaded areas should be relatively easier to identify. Suspect areas will be those areas with more snow that may appear fat, bulbous, pillowy, and smooth. Expect these wind loaded areas to be the most prevalent on the leeward side of ridges and cross-loaded gully features. Those lee aspects may be identifiable by a cornice or “wind lip.”

Especially dangerous areas will be terrain steeper than 30-35º where the snow is relatively deeper, denser snow overlies looser and weaker (faceted) snow, and the snow has a punchy and/or hollow feel.

The good news is that, after spending an extensive amount of time in the Western Chugach this week, snow coverage in the greater Anchorage area mountains this early in the season hasn’t been this good since 2011 (which was the beginning of what became the legendary “snowpacalypse” season).

Other good news is that, while it was extremely cold at the lower elevations of civilization the past several days, a temperature inversion was in place and it was significantly warmer in the mountains. Upper elevation temperatures were in the 20s. Combined with solar radiation, this reduced malignant metamorphism of the snowpack and slowed the faceting process.

*Follow the hyperlinks to learn more about avalanche terminology

We ask that you support a professional avalanche forecasting program for the greater Anchorage area Western Chugach Mountains and Chugach State Park (not solely a public observations program hosted by a Forest Service avalanche center an hour away from Anchorage staffed by professionals without much experience with the terrain and snowpack local to Anchorage). The notion that a public observations platform by itself, without professional contextualization and forecasting, is a remedy for the numerous avalanche accidents resulting in casualties and fatalities in the greater Anchorage area Western Chugach Mountains is ridiculous. Observations can be misleading, and contribute to a lemming effect that can have negative consequences both in regard to avalanche safety and overcrowding access at precarious neighborhood/residential trailheads in the greater Anchorage area.