Summit & Central Kenai Mtns

Recent Avalanches: There has been widespread avalanche activity in Summit over the past week. Notably wind slab avalanches were reported throughout the forecast zone as well as new glide avalanches on Gilpatrick Mtn and John Mtn. There have also been large avalanches on buried weak layers in Lynx Creek and Johnson Pass, which have a similar snowpack to Summit Pass.

Weather Recap: Last weekend skies were clear with strong winds and above freezing temperatures (40 to 45 F) in Summit. On Monday and Tuesday, a warm storm brought 0.7″ of SWE in the form of rain to elevations around 2300′. On Wednesday the storm dissipated and temperatures finally dropped to below freezing. Wednesday night into Thursday, another brief pulse of weather brought snow to the valley floor in Summit, with 10″ of new snow accompanied by strong winds from the east.

Weather Forecast: A low pressure system is forecast to arrive on Friday night, bringing clouds and a few inches of snow. On Saturday, ridgetop winds from the northwest should increase throughout the day from 10 to 35+ mph. Winds will decrease again on Sunday morning averaging 5 to 10 mph and clouds are expected to dissipate throughout the day. Over the weekend temperatures are forecast to drop to lows around 10 F with highs in the teens to mid 20’s. 

New glide avalanche on Gilpatrick Mtn. Photo 2.21.202

As the storm approaches over the weekend, strong northwest winds will increase throughout the day on Saturday from 10 to 35+ mph peaking overnight on Sunday. The ~10″ of new snow that fell this week will be blowing into sensitive wind slabs that may be 1 to 2′ deep. Wind slabs are typically easy to trigger and can cause avalanches within 24 to 48 hours after a wind event. Areas that typically harbor wind slabs are below ridgelines, rollovers, and in cross-loaded gullies. Red flags such as blowing snow, hollow snow over softer snow, and cracking beneath you are great indicators that you are traveling on a slope that is wind loaded. We recommend avoiding steep wind loaded terrain especially at higher elevations where there is potentially more snow capable of creating larger winds slabs over a buried weak layer. More about this in Problem 2.

Storm Slab: With 10″ of new snow in Summit over a rain crust, it may be possible to trigger an avalanche on the new snow/crust interface. This is a concern because we are not sure how well the crust is bonding to the new snow. Take the time to look for red flags such as cracking and use informal tests such as hand shear and test slopes to see how well the snow is bonding before committing to steeper terrain. To avoid this problem altogether choose slopes below 30 degrees until the new snow has had time to bond to the rain crust.

Wet Loose: The sun is back and with that wet loose avalanches will be possible, especially on steep south facing slopes near rocks and vegetation. Although temperatures are supposed to be cold this weekend, we are approaching the season where solar triggered avalanches will become more common.

With rain reaching 2300′ there is now a rain crust over the Jan weak layer at lower to mid elevations. Typically a crust makes it more difficult to trigger an avalanche on a buried weak layer. However, in places where the crust is thinner and where there is no crust (above 2000′) it is still possible to trigger an avalanche on the Jan weak layer that is now buried 1 to 3′ deep. These include areas such as mid-elevation tree skiing that typically feels like a safer alternative to more exposed faces. Wind slabs forming over the weekend will also be adding stress to this weak layer. It is uncertain how sensitive this layer is to being triggered, and an avalanche on this layer has the potential to be larger and run further than expected. While red flags such as cracking, collapsing, and whumphfing sounds can be great indicators that the slope is capable of creating an avalanche, there may be no evidence until an avalanche occurs. It is also possible that these avalanches could be triggered remotely, meaning you could cause an avalanche on an adjacent steep slope. To avoid this problem, choose terrain with slopes lower than 30 degrees which will allow this weak layer time to stabilize.

Although it has been almost two weeks since Summit Pass has experienced an avalanche failing on this weak layer, Lynx Creek, Johnson Pass as well as mountains in the Seward region have all had avalanches that likely released on this layer over the past week.

Large avalanche in Lynx Creek. Because the avalanche spread across multiple gullies, we believe it may have failed on the Jan buried weak layer. Photo by John Sykes 2.22.2024 

Two glide avalanches were observed over the past week in Summit Pass. This is telling us that it is possible that new glide cracks may be forming over the weekend as well. These look like “brown frowns” that can spontaneously release into glide avalanches which can be very large and run to lower elevations.  It is best to avoid traveling underneath glide cracks, however, if you do not have an alternate route, expose one person at a time, and move quickly underneath them.