DANGEROUS AVALANCHE CONDITIONS
The avalanche danger in Chugach State Park is elevated and expected to increase through Monday due to continued strong winds and the potential for several inches of new snow.
Very sensitive wind slabs that have the potential to release naturally or by human triggers exist in specific areas above 2500′: leeward (primarily West to North aspects) and cross-loaded terrain steeper than 35 degrees.
With continued strong winds and the potential for several inches of new snow Monday the danger will continue to rise. As the wind slab danger increases, wind slabs may be possible at lower elevations (to 2000′), on lower angled terrain (to 30 degrees), and up to D2.5 in size.
The Anchorage Avalanche Center received numerous reports of dangerous avalanche conditions due to strong winds and severe wind loading on Sunday. A dangerous wind slab avalanche released naturally Saturday or Sunday very close to the main Flattop trail (photo courtesy of the CNFAIC: click here to go to that site for more info):
Keep in mind that wind slabs and persistent slabs may become hidden beneath new snow for a period of time, as there may be a lull in wind speeds as the incoming storm deposits fresh snow Monday morning. Winds are expected to again increase and will blow new snow into fresh wind slabs as well as continue to load existing wind slabs and persistent slabs.
Touchy to unreactive persistent slabs up to D2.5 in size may exist in isolated areas and be possible to trigger above 2500′ on terrain steeper than 35 degrees, especially leeward (West to North) and cross-loaded aspects where these slabs will be further stressed by recent wind loading and new snow Monday.
These persistent slabs have the potential to be the largest and most inherently dangerous avalanche problems. Persistent weak layers (primarily advanced facets and depth hoar) are widespread throughout Chugach State Park, and in isolated areas the recipe may be right for a large persistent slab release.
Wet avalanches will be possible, and likely if the sun comes out, on solar (East to West) aspects above 2000′ where the terrain is steeper than 35 degrees. Point releases and loose wet avalanches (sluffs) may occur naturally as we receive new snow Monday. Wet slabs are possible with warm temperatures, solar radiation, and/or rain as meltwater percolates through the snowpack and lubricates weak layers or weak interfaces underlying slabs.
Fresh snow that receives initial warmth and sun will be very susceptible to avalanching. The wet avalanche danger will be a problem through the remainder of the season, generally increasing in the afternoon with daytime warming.
Cornices are reaching their peak size for the season. They’re extra sensitive this time of year due to being at their largest and from warm temperatures and solar radiation. It will be especially important to give them a wide berth due to recent snow and wind that has increased their size and susceptibility to failing both naturally and from human triggers.