Chugach State Park

Recent Avalanches: Over the past week, we have had seven observations in the Chugach State Park with three avalanches.  Two human-triggered avalanches occurred in the Falls Creek area off the Seward Highway on February 4th. The avalanches were thought to have failed on the layer of near-surface facets under a stiff wind crust beneath the last two most recent storm events. A similar problem likely exists across most of the Front Range right now.  Another observation mentioned a natural wind slab avalanche on Rusty Point on Saturday, February 3rd.

While the other observations did not mention avalanches, several red flags that illustrate signs of instability were noted. In Arctic Valley on Wednesday, February 7th, the observer experienced “eight collapses and whoompfs in clearly wind-loaded and pillowed areas…the collapses were about 10″ down in the snowpack,” and then shooting cracks were seen on Rendevous Pass on Thursday, February 8th.

The forecasting team relies heavily on public observations and we always appreciate any information you all have to share. It takes a community to make an avalanche center run. Thank you!

Falls Creek avalanche. Photo: Mike Records 2.2.24

Shooting cracks were observed on Rendezvous Pass. Photo: Peter Wadsworth 2.8.24

Weather Recap: The Front Range has received roughly 5″ of new snow in the past week. There were several significant wind events this past week. Saturday morning through Sunday afternoon, we had a wind event from the north with sustained 20-50 mph winds. Another wind event occurred Tuesday night through Thursday with sustained 20-30mph winds with gusts up to 50 mph from the southeast. Temperatures have been “warm” in comparison to the last few chilly weeks. At the beginning of last weekend, we were still seeing low temps in the -20 F to 0 F range (The South Fork of Eagle River weather station dipped low again with a reading of -36 F on February 2nd. Brrr…) and then we saw a gradual warm-up starting last Sunday. Overall temperatures ranged from -20 F to 40 F with an average of around 22 F.

Snow depth continues to vary across the region. Conditions range from bare ground to over nine feet of snow with an average of about four feet.

Weather Forecast: A storm is forecast to hit the Front Range today through Saturday evening. The storm is forecast to have sustained 20-50 mph winds with gusts up to 85 mph with 5-7″ of new snow. The wind looks like it will die down to 10-20mph Saturday evening through Sunday morning and then pick up again to 20-30 mph winds Sunday afternoon and evening. Light precipitation (0-2″) is forecast for Sunday, but the bulk of the new snow will come in with the strong winds  today and Saturday. Temperatures are forecast to range from the high teens to the low thirties this weekend with an average of around 25 F.

The theme of this past week and this weekend is wind, wind, and more wind. Pay attention to active loading and consider the potential for natural wind triggered avalanches. The wind event this weekend is forecasted to come from the southeast. The wind events from this past week have come from both the southeast and the north. Similar to last week’s Weekend Outlook, wind events from different directions can create wind slabs in more unusual spots from cross-loading and loading mid-slope. To identify areas with wind slabs, feel for firmer, hollow snow on the surface. Carefully evaluate cross-loaded gullies, wind-loaded ridges, and rollover features, and be on the lookout for shooting cracks. Keep in mind that stiffer wind slabs often fail once you are farther out onto the slope and can surprise you. 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.

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.

Wind slab in Falls Creek. Photo: Mike Records 2.4.24

Shooting cracks were observed on the southwest face of Peak 1080′. Photo: Claire Bicknell 2.7.24

With the added stress on the snowpack from the new snow and strong winds this weekend and the presence of buried weak layers in the snowpack, we are concerned about potential for triggering a larger more dangerous avalanche. For the past three weeks, we were able to get some reactive stability test results on the near-surface facet layer roughly 13” to 15″ down from the snow surface that was buried in early January. The Falls Creek avalanche was thought to have failed on this layer. Furthermore, there have been new near-surface facet layers created in the cold-clear weather in between recent wind events. Additionally, there is a persistent weak layer we are still monitoring at the base of the snowpack at elevations over 2,500’. This a layer of depth hoar and basal facets (weak, sugary snow).

New near-surface facet layers were observed in between recent wind events. Photo: 2.7.24