Summit & Central Kenai Mtns

Archives
Issued
Fri, January 5th, 2024 - 7:00AM
Expires
Sat, January 6th, 2024 - 7:00AM
Forecaster
Daniel Krueger
Conditions Summary

Weekend Avalanche Outlook

Saturday, Jan. 6 – Sunday, Jan. 7

Bottom Line: With stormy weather forecasted to bring strong east winds and 6-10” of new snow by Sunday evening, wind slabs are our main concern over the weekend. These may be up to 1-2’ deep, large enough to bury a human or sled. In some areas this snow may be falling on weaker snow that will make an avalanche easier to trigger. Looking for red flags can indicate when snow is becoming unstable as well as being aware of an increase in avalanche conditions on Sunday.

Recent Avalanches

Recent Avalanches: The glide crack and glide avalanche cycle in Summit is still occurring. These have been seen on Fresno, Wilson, Manitoba, and Gilpatrick. There has been no known human triggered avalanches in the Summit Lake area.

Weather Recap: Last weekend the Summit lake area had cold, clear days. Tuesday into Wednesday a brief storm brought roughly 3” of snow equaling 0.3” snow water equivalent (SWE) accompanied by strong ridgetop winds out of the east. Temperatures rose to above freezing briefly in Summit Pass. 

Weather Forecast: We are anticipating a brief storm to reach the Kenai peninsula Saturday afternoon and last into Monday morning. Clouds will begin to move in Saturday afternoon accompanied with east winds increasing into the 10 to 20 mph range. Sunday will be cloudy and windy with east winds averaging 20 mph and 50+ mph gusts at higher elevations. 6-10” of new snow is forecasted to fall by Sunday evening. Temperatures in the 20’s F on Saturday are expected to increase on Sunday to the low 30’s F.

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 Avalanche.org

Our primary concern is wind slab avalanches over the weekend. We are expecting this hazard to increase with the arrival of the storm on Sunday morning. The combination of ridgetop winds from the east gusting as high as 50 mph and 6-10” of new snow will likely create fresh wind slabs around 1-2’ deep by the end of Sunday. Areas where we can usually see wind slabs are below ridgelines, across gully features and below rollovers. Watch for red flags such as blowing snow, recent avalanches, cracks that shoot out from your machine, board, or skis and whumpfing sounds. 

Across the Summit area weaker snow was observed last week on the surface that will be buried by this weekend’s storm. This may make storm snow and wind slabs more reactive and easier to trigger. This will be important to assess as conditions change.  If you are skinning or snowmachining, look for recent avalanches, test small safe slopes, and be aware of any cracking or collapsing as you travel in the backcountry. If you feel like sharing your findings, take some pictures and let us know. Help out by submitting observations here!

Last weekend’s surface hoar may be under this weekend’s storm and wind slabs. Photo by Andy Moderow 12.30.2023

 

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 Avalanche.org

There are a couple layers in the snowpack we are keeping track of. The first is surface hoar buried around 1’ deep, which has been identified in several pits but is not showing signs of being reactive nor have we seen or heard of any avalanches failing on this layer. However, it is a layer we are watching especially as it gets loaded from this storm. 

Additionally, the Thanksgiving crust is buried roughly 3’ deep. This layer has also not given us a reason to be overly concerned. With that said, crust/facet combos like the Thanksgiving crust can “wake up” or be more unstable with a significant new load of snow and in areas with shallower snowpacks, such as Summit Lake. The forecast snow amounts this weekend are not likely to be enough snow to overload the layer, but it’s still something to keep on our radar.

Summit pit showing buried surface hoar and the Thanksgiving crust. Photo by Any Moderow 12.30.2023

 

 

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

Glide cracks and avalanches are still being observed across the Summit area. Because these avalanches release to the ground, the cracks that precede them can be easy to spot as “brown frowns” as they open or “brown spots” when they release into an avalanche. It is important to minimize exposure under these glide cracks because they can spontaneously release and be large and dangerous.

Glide avalanches on South Gilpatrick. Photo by Trevor Clayton 1.1.2024

 

 

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