Chugach State Park

Recent Avalanches:  Over the past week, we have had four observations in the Chugach State Park with one reported large avalanche in Falls Creek on a west aspect. The start zone for the avalanche was around 2,700 feet in elevation. The slide appeared to be triggered naturally from the January 7th cycle and was reported to have likely failed on old snow within the snowpack. Thank you to everyone who has submitted observations! We always appreciate any information the public has to share.

Images of Falls Creek avalanche. The crown is illustrated in the first photo, and the debris pile is in the second photo. Photo taken 01.08.24

Weather Recap: In the past week, the Front Range has received approximately 8” of new snow with 10-35 mph winds with gusts up to 60 mph at ridgetops predominantly from the southeast at higher elevations. Temperatures at Glen Alps and Arctic Valley ranged from teens to mid-30s F, averaging around 25F. At the bottom of the South Fork of Eagle River valley, temperatures dipped as low as 1F.  The overall snow depth is highly variable in the Front Range right now. The winds have scoured the landscape in many areas, and bare ground is visible. In areas that tend to fill up with snow, like gullies and alpine bowls, the snowpack is deeper and potentially harboring buried weak layers.

Weather Forecast: Starting this morning (January 12th), a front moved in with increasing winds, clouds, and snow. Winds are forecast to continue averaging 15-30 mph with gusts up to 60 mph from the SE for roughly 12 hours, with a possible lull late tonight and early Saturday morning. Saturday winds will ramp up again to 15-30 mph with gusts up to 50 mph for roughly 24 hours. This weekend, 2-3” of new snow is expected, with precipitation starting Sunday morning and tapering off later that evening. Temperatures are forecasted to stay pretty consistently in the high teens to high twenties. The rain/snow line might creep up as high as 200’ on Saturday night. Looking out to early next week- northerly outflow winds are forecast for Tuesday. This means cold winds will be channeled from the north through gaps in the terrain.

Bare tundra and wind-scoured peaks in Glen Alps Recreation Area. Photo taken 1.12.24

Wind Slabs: With a front moving in today bringing between 2-3” of new snow and sustained 20-60 mph winds from the southeast, wind slab avalanches are expected. Even if new snow amounts are only a few inches, wind slabs will still be a concern due to a foot of loose snow on the surface in many areas that could rapidly be deposited into slabs in exposed terrain. Both natural and human-triggered avalanches could occur this weekend.

A common wind-loaded face in the Front Range that gets high traffic use is the northwest face of Flattop, just behind Blueberry Knoll. The surrounding area is a lower-angle non-consequential terrain. However, this particular slope and face is steep enough to slide and is often wind-loaded. It has been common in the past for hikers to want cut up through this slope to save some time, yet this area has the potential to avalanche and bury a person.

To identify areas with wind slabs, look for active wind transport loading slopes and feel for firmer, hollow snow on the surface. Using small test slopes can be a good way to check whether wind slabs are reactive to human triggers in the area you are traveling. Wind slabs can be avoided by sticking to sheltered or wind-scoured areas. Keep in mind, given the weak snow layers buried deeper in the snowpack (Problem 2), a relatively small wind slab triggered near the surface has the potential to step down to a deeper weak layer.

Snow transport at the end of Powerline Pass. Photo taken 01.11.24

Signs of wind-affected snow in South Fork of Eagle River. Photo taken by Maddie Hall on 01.09.24

Persistent Slab:  There are three main layers we are watching within the snowpack. The most concerning is the layer of facets (weak, sugary snow) at the base of the snowpack at higher elevations. The second layer is a thin layer of facets about 20” deep, which exists right above the Thanksgiving crust. This has been observed at lower elevations. Lastly, the interface between near surface facets and wind slabs ~6” down from the current snow surface. Over the past week, we have not had concerning stability test results and we don’t know of any avalanches that have released on those layers. However, we are still highlighting these persistent weak layers because of their potential to cause large and destructive avalanches, and the new snow and strong winds adding stress this weekend.

Photo of identifying layers of concern in the snowpack in Eagle River at 3,500’. Photo taken 12.09.24

Thanksgiving crust observed at 2,900’ in Eagle River. We are monitoring the thin layer of facets above the crust. Photo taken 01.11.24