Summit & Central Kenai Mtns

Archives
Issued
Fri, February 9th, 2024 - 7:00AM
Expires
Sat, February 10th, 2024 - 7:00AM
Forecaster
Daniel Krueger
Conditions Summary

Weekend Avalanche Outlook

Saturday, Feb. 10 – Sunday, Feb. 11

Bottom Line: A storm impacting Summit will produce strong winds and up to 6″ of new snow making it likely to trigger a wind slab avalanche up to 1′ to 2′ deep. It is also possible that storm snow and wind slabs may stress a buried weak layer enough to produce deeper and larger avalanches at all elevations, including lower elevation terrain. During stormy weather we recommend avoiding steep wind loaded features and avalanche terrain in general.

Special Announcements

The Chugach National Forest Avalanche Center has issued an avalanche warning through the National Weather Service for Girdwood, Portage, Turnagain Pass, Moose Pass, and Seward that will end at 9pm Saturday, February 10.

The National Weather Service has issued a winter weather advisory for Turnagain Pass through 9pm on Friday, February 9th

Snowmachine access in the Kenai Mountains: Here is a map showing snowmachine access in Summit Pass. This is a great tool to better understand and travel in areas open to snowmachining. You can also download it to your phone to use in the field. This link provides information on how to use the winter recreation map layer.

Recent Avalanches

Recent Avalanches: A natural avalanche was reported today (Feb 9) on Templeton Mtn. It is possible the avalanche released last night due to high winds transporting fresh snow.  Otherwise, the last reported avalanche was a wind slab avalanche on Tributary Mtn on Jan 30. The slab was around a foot deep and about 80ft wide. That being said, visibility in Summit earlier this week has made it difficult to see avalanche activity. If you see recent avalanches, please consider submitting an observation.

Weather Recap: Last weekend around 5″ of new snow fell accompanied with northeast winds gusting to 30 mph. From Tuesday into Wednesday Summit Pass was mostly cloudy and windy with ridgetop winds averaging 20 to 30 mph and temperature increasing from single digits to low 30’s F. A storm arrived on Thursday afternoon bringing 1″ of snow overnight, northeast winds gusting to 60+ mph and above freezing temperatures in the pass.  Friday delivered 35 mph gusts by the highway, 50+ mph on ridgetops, a few inches of snow, and above freezing temperatures (35 F).

Weather Forecast: The storm that arrived on Thursday is forecast to bring cloudy skies and up to 6″ of new snow to Summit over the weekend with strong winds. On Friday night into Saturday morning sustained winds 20 to 30 mph from the southeast are expected with 40+ mph ridgetop winds, a few inches of new snow, and temperatures dropping to the mid 20’s F. Saturday is likely to receive another few inches of snow and sustained southerly winds averaging 15 to 25 mph with ridgetops gusts 30 to 40 mph and temperatures averaging 20 to 30 F. On Sunday the sun may shine through cloudy skies as the storm begins to break up with ridgetops winds from the south averaging 10 to 20 mph, 30+ mph gusts a few lingering flurries and temperatures averaging 15 to 25 F.

Recent natural avalanche on Templeton Mtn likely releasing on Feb 9. Photo by Katie Mohn 2.9.2024

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

Strong winds are forecast out of the east on Friday night then switching out of the south on Saturday which will cause wind slabs to form on multiple aspects. These winds are expected to transport new and old snow into touchy wind slabs 1 to 2′ deep at all elevations that is affected by the wind including below treeline.  Wind slabs can be found on the leeward side of wind affected features such as below ridgelines, convex rollovers, and in cross loaded gullies. Red flags such as natural avalanches, blowing snow, and shooting cracks indicate that you can trigger an avalanche. The safest option is to avoid steep wind loaded slopes instead riding lower angle terrain not affected by the wind until the snowpack has had time to settle.

It is possible that fresh wind slabs will also be forming over a persistent weak layer buried 1′ deep that will increase the likelihood of triggering a much larger avalanche. More about this in our problem 2.

Lonestar Mtn with this week’s winds scouring the windward slopes and loading leeward slopes. Photo 2.6.2024

The Alaska Railroad at Mile 43 Peak weather station records wind patterns similar to Summit’s ridgetop winds. This wind rose is showing very strong winds from the east northeast. 

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

The weak sugary snow and surface hoar that formed during January’s period of cold clear weather is now covered by 1′ of snow.  This weekend’s strong winds and new snow will add stress to this layer however, it may not be enough to cause natural avalanches. If that is the case then this layer may not show signs of instability until it is triggered. It has been observed from the highway to 2500′ making it a widespread issue including areas below treeline that has been relatively safe for most of the season. We recommend staying out of avalanche terrain (30 degree slopes or steeper) until the storm subsides and we get a better idea as to how sensitive the layer is. It is also important to mention that while red flags such as cracking, collapsing, and recent avalanches can provide some information, persistent slabs may not give you any clues until they avalanche.

 

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

It has been over two weeks since a glide avalanche was reported in Summit Pass. As always try to avoid traveling under these glide cracks because it is possible for new or old cracks to release into an avalanche.

Weather
Fri, February 9th, 2024
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.