Summit & Central Kenai Mtns

Archives
Issued
Fri, December 22nd, 2023 - 7:00AM
Expires
Sat, December 23rd, 2023 - 7:00AM
Forecaster
Daniel Krueger
Conditions Summary

Weekend Avalanche Outlook

Saturday, Dec. 23 – Sunday, Dec. 24

With 10-20” of new snow expected this weekend, avalanches failing within new and windblown snow will be our main concern. This amount of snow will create dangerous conditions where natural and human triggered avalanches are very likely.  Additionally, this storm could trigger a much larger avalanche on weaker snow buried deeper in the snowpack. We recommend staying out of avalanche terrain and areas that have steep slopes above you as these avalanches may run all the way to the valley bottom.

We have issued a Backcountry Avalanche Warning through the National Weather Service from 6am Saturday, Dec 23, to 6am Sunday, Dec 24.

Roof Avalanches: The approaching storm may bring the rain line to 1200’ which will saturate feet of snow that has piled up on roofs over the past week. This will increase the chances of roof avalanches in the Cooper Landing and Moose Pass communities. Be careful when you are entering or exiting buildings, keep an eye on children and pets, and be mindful of where you park your vehicles.

Special Announcements

Happy holiday storm this Christmas! Whether or not you are a fan of the holidays, the gift of snow has been rare in other parts of the world this year so take the time to get some in the great white this winter.  Be safe this weekend!

The National Weather Service has issued a variety of winter storm warnings / blizzard warnings / high wind warnings / winter storm watches throughout Southcentral Alaska.

Recent Avalanches

The Summit Lake area saw a handful of natural avalanches that likely occurred over the weekend and during the stormy weather Monday and Tuesday (Dec 18-19). Some of these avalanches were big enough to bury a person and we believe most failed within the new storm snow. More concerning were reports of an avalanche on the southwest side of Wrong Mountain with an estimated 6’ crown that may have failed on the Thanksgiving crust. Glide avalanches were also observed on the south side of Manitoba. 

Weather Recap: In the past week, Summit Pass has received roughly 15” of low-density snow with ridgetop winds gusting to 50 mph. Winds calmed, and clouds began to break up on Wednesday and Thursday. Earlier in the week temperatures averaged 20-30 F followed by a colder trend towards the weekend around 5-10 F as skies cleared.

Weather Forecast: We are anticipating an active storm cycle beginning today that will increase in intensity overnight. We are expecting winds starting to increase Friday night averaging 20-40 mph from the east with higher gusts in the 50-60 mph range, continuing all day Saturday and finally decreasing Sunday evening. Snowfall in Summit Pass could amount to 6” by Saturday morning with another 6” throughout the day. By Sunday the snow should be decreasing with another 2-6” throughout the day.  This storm will come in warmer with the rain line creeping as high as 1200’ on Saturday morning.

On Manitoba peak looking at a storm slab and glide cracks on the ridge to the north. Photo by Elias Antaya 12.21.2023

 

 

Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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 Avalanche.org

As this storm ramps up, we are expecting up to 12-20” of new snow and strong east winds averaging 20-40 mph. Snowfall will be at its heaviest early Saturday morning continuing throughout the day into Sunday evening. To make matters worse, there have been reports that this snow could be falling on surface hoar creating the perfect recipe for a touchy storm slab 1-2′ thick. Where this layer is preserved it could create the classic storm slab over weak layer situation where these avalanches may release in lower angle slopes less than 30 degrees that are usually considered safer to travel.  

If the storm verifies, this amount of wind and snow will place a lot of stress on the snowpack. This will be a widespread issue affecting all aspects and elevations where avalanches are very likely to release naturally and will be large enough to bury a person. Traveling in avalanche terrain is not recommended. That includes traveling under avalanche terrain where avalanches will likely run a long distance into low angle terrain. If you are itching to get out for a holiday tour this weekend it may be a good time to enjoy cross country skiing in the flatlands or choosing fun low angle pow turns. 

Avalanche crown with numerous fractures on S aspect of Manitoba. Glittering surface hoar on foreground slope. Photo by Elias Antaya on 12.20.23

 

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 Avalanche.org

We are keeping track of a layer of facets buried around 3’ deep that has been found either just above or in the middle of the Thanksgiving Crust (TC).  We believe that this layer was the culprit in a large natural avalanche observed on Wrong Mtn near the Sterling Wye, which likely released on Tuesday during the stormy weather, Otherwise, we know of no recent avalanches that look to have failed in these buried facets. Snow pits and stability tests have not shown alarming results yet this weekend’s storm could overload and “wake up” this layer. If this was the case, avalanches may be 3-5’ thick or more. This storm will be a great natural “test” to see how fragile the weak layer is. We do not advise traveling in avalanche terrain, including flat areas under large avalanche paths. Once again this could be a great day to play Catan or stick to safe angles not on or under avalanche hazards. 

Additional Concern
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

This past week multiple glide avalanches were observed, and new glide cracks are opening in the Summit area. Because these avalanches release to the ground it can be easy to spot them as “brown frowns” as they open or “brown spots” when they release. It is important to minimize exposure under these glide cracks because they can spontaneously release and be large and dangerous. 

Glide cracks and glides avalanches, on the south side of Manitoba. Photo by John Sykes 12.20.23

 

 

 

 

Weather
Fri, December 22nd, 2023
Fri, December 22nd, 2023
Weather Forecasts

NWS Point Forecast: Point forecast for the Summit Lake area.

NWS Avalanche Weather Guidance (AVG) forecast page: Mountain weather forecasts for the region. Zoom in on the map to find point forecasts for Summit.

Windy.com Spot Forecast: Spot forecast for Summit (tip: compare models using the links at the bottom of the page).

 

Weather Stations

Summit Creek Snotel

AK DOT&PF Summit Lake Weather Station 

AKRR Ridgetop Weather Station

Observations
Recent Observations for Summit & Central Kenai Mtns
Date Region Location
04/10/24 Summit Observation: Manitoba
04/10/24 Summit Observation: Colorado
04/07/24 Summit Observation: Fresno
04/06/24 Summit Observation: Tenderfoot
04/04/24 Summit Observation: Gilpatrick North
03/27/24 Summit Observation: Colorado
03/24/24 Summit Observation: Near Tern Lake and Near Sixmile Creek
03/21/24 Summit Avalanche: Manitoba
03/21/24 Summit Avalanche: Summit eastside
03/21/24 Summit Observation: Johnson South
Riding Areas

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