Chugach State Park

Fri, December 15th, 2023 - 7:00AM
Sat, December 16th, 2023 - 7:00AM
Mary Gianotti
Conditions Summary

Weekend Avalanche Outlook

Saturday, Dec. 16  – Sunday, Dec. 17

There are two main avalanche problems we are most concerned with in the Chugach State Park this weekend. The first problem is wind slab avalanches. The combination of strong winds and 12” of light new snow on the surface will make natural and human triggered wind slabs likely. The second problem is triggering a larger slab avalanche that breaks in weak snow at the middle or base of the snowpack.

The overall snow depth is highly variable in the Front Range right now. In wind exposed areas the new snow from this week is sitting pretty much on the ground, with lots of rocks and branches hiding underneath. In areas that tend to fill up with snow, like gullies and alpine bowls, the snowpack is deep and potentially harboring buried weak layers.

Special Announcements

Welcome to the Chugach State Park conditions page. We are in the process of ramping up a weekend avalanche report for Anchorage’s Front Range. Our goal is to provide avalanche information for high use areas of the Chugach State Park in an effort to assist recreationalists in making informed and safe backcountry travel decisions.

Areas include the Anchorage Front Range (i.e., Flattop/Glen Alps) and the South Fork of Eagle River. The outlook’s primary audience will be winter hikers, backcountry skiers/snowboarders, snowmachiners, snowshoers, fat bikers, and climbers.

Recent Avalanches

There were a few dry loose avalanches triggered this week and one small windslab (details here). I observed small, isolated, natural dry loose avalanches on my field day on Thursday.

Weather Recap: In the past week, the Front Range has received roughly 12” of low-density snow with moderate winds at ridgetops and higher elevations. Temperatures ranged from 8F to 34F with an average of around 16F.

Weather Forecast: Starting Saturday morning it looks like things are going to get windy with high clouds and snow starting in the afternoon. Winds are forecast to average 30-60 mph from the SE with higher gusts for roughly 12 hours. On Sunday the winds should decrease to averages of 15-25 mph with lower clouds and light snowfall expected throughout the day. We are expecting 2-6” of snowfall, with precipitation starting Saturday afternoon and continuing through Sunday evening. The temperatures will rise from the low teens to the low thirties F during the day Saturday and then drop back into the teens on Sunday evening. Rain line might creep up as high as 1000’ on Saturday evening while the strong winds are peaking, but the weather models are uncertain.

Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at

Sustained moderate to strong winds from the southeast are forecasted for this weekend. With a foot of loose snow currently sitting on the surface, we can expect these strong winds to rapidly form wind slabs 1-3’ deep in exposed terrain. These are likely to produce both natural and human-triggered avalanches this weekend.

To identify areas with wind slabs look for active wind transport 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. You can avoid wind slabs 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.

Dry Loose Avalanches are very likely in steep terrain that is sheltered from the winds.  We recommend avoiding terrain traps, skiing/riding one at a time, using safe zones and sluff management techniques when appropriate.

View of Hidden Peak and The Ramp from Peak 4. Photo taken 12.14.2023

Avalanche Problem 2
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at

There are two weak layers we are concerned about in within the snowpack. One is a thin layer of facets about 12” deep which exists right above the Thanksgiving crust at lower and mid elevations. The other is a layer of larger facets at the base of the snowpack, which has been observed at higher elevations. Over the past week we have not had concerning 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 very large and destructive avalanches. To avoid this avalanche problem entirely we recommend sticking to lower angle terrain.

Snowpack structure in mid elevation where the facets over the Thanksgiving crust are an issue. Photo 12.12.2023

Snowpack structure in high elevation areas with weak faceted snow at the ground. Photo 12.14.23

Facets at the base of the snowpack found at 4,000’ on Thursday at Peak 4. Photo 12.14.2023

Recent Observations for Chugach State Park
Date Region Location
05/29/24 Chugach State Park Avalanche: Harp mtn west aspect
05/07/24 Chugach State Park Observation: Mt. Eklutna
04/27/24 Chugach State Park Avalanche: Chugach Front Range Powerline Valley
04/16/24 Chugach State Park Observation: South Fork of Eagle River
04/13/24 Chugach State Park Avalanche: South Fork Hiland Road
04/10/24 Chugach State Park Observation: Chugach Front Range Flattop
04/09/24 Chugach State Park Observation: South Fork of Eagle River
04/08/24 Chugach State Park Avalanche: Arctic Valley/ Gordon Lyon
04/06/24 Chugach State Park Observation: Eagle River South Fork
04/06/24 Chugach State Park Avalanche: False Peak

This is a general backcountry conditions summary. This advisory does not apply to highways, railroads or operating ski areas.