Summit & Central Kenai Mtns

Archives
Issued
Fri, March 1st, 2024 - 7:00AM
Expires
Sat, March 2nd, 2024 - 7:00AM
Forecaster
Daniel Krueger
Conditions Summary

Weekend Avalanche Outlook

Saturday, March 2 – Sunday, March 3

Bottom Line: Lingering wind slabs 1 to 2′ deep that formed this week could be triggered on steep wind loaded slopes. There is also a chance to trigger a larger avalanche 1-3′ deep on a buried layer of weak snow in mid to upper elevations. Additionally, dry loose avalanches are a concern on steep wind protected slopes. We recommend assessing slopes that may be wind loaded and a cautious approach into avalanche terrain because it is uncertain how likely a surprise avalanche can be triggered on the buried weak layer.

 

Special Announcements

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: Over the past week a large natural avalanche was reported on Butch Mtn in Summit and in the Carter Lake area, which likely released over the weekend on the Jan buried weak layer. Wind slab avalanches were also observed on the southeast slope of Gilpatrick on Wednesday (Feb. 28). It is likely more wind slab avalanches released this past week as slopes were continuously being loaded with snow.

Weather Recap: Last weekend Summit received 0.4″ SWE (~4″) of new snow accompanied by strong winds out of the northwest. On Sunday clouds cleared but northwest ridge top winds continued to blow with 40+ mph gusts and temperatures in the mid 20’s. From Monday into Thursday a similar pattern of partly cloudy skies, and strong winds from the northeast and northwest continued to hammer the mountains in Summit. Temperatures throughout the week dropped steadily from the mid 20’s F to below zero F.

Weather Forecast: Cold and stable weather are forecast to bring light to moderate winds and no new snow to Summit Pass over the weekend. Saturday looks to be mostly sunny with light winds (0 to 10 mph) from the west. Expect clouds to increase on Sunday morning and light winds from the south (0 to 5 mph) with 15mph ridgetop gusts. On Saturday temperatures are expected be cold (-10 to 10 F) increasing throughout the day into Sunday with temperatures expected to be just below 0 to 20 F.

Large avalanche in the Carter Lake area just south of Summit that crossed multiple runouts. We believe this failed on a weak layer on Feb 22. Photo by Heather Thamm 2.23.2024 

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

Blowing winds from last week deposited wind slabs on all aspects from mid to upper elevations. These should be harder to trigger as winds are forecast to decrease over the weekend. That being said, there is a chance you could trigger a wind slab 1 to 2′ deep on steep wind loaded slopes.  IF you do see snow blowing where you are traveling, be aware that new wind slabs are forming.  These will likely be found below ridgelines, rollovers, and in cross loaded gullies. Probing for stiff snow over soft snow and testing small slopes to see if they crack beneath you are all good tests that indicate you are traveling on a slope that has been wind loaded. If you want to avoid this problem all together, searching for soft snow is a safer option.

Dry Loose: It is possible to trigger dry loose avalanches in steep wind sheltered terrain. These avalanches are known to carry a person off a cliff, into a tree, or into a terrain trap where snow can pile up and bury a person. Small test slopes can give clues as to how loose the snow is as well as establishing safe spots that allow loose snow to move past you are all good ways to avoid getting caught and carried.

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. These also have the potential to trigger a wind slab below. The sun warming the snow can also make wind slabs easier to trigger. Although temperatures are supposed to be cold over the weekend, we are approaching the season where solar triggered avalanches will become more common.

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

Less than a week ago there were two large avalanches on Butch Mtn and in the Carter Lake area that likely failed on the buried Jan weak layer. This is a great indicator that a persistent slab avalanche 1-3′ deep is still possible. In the Summit area this weak layer is healing slower than in Turnagain Pass as this observation explains. This problem will be more likely at elevations above 2,000′ which includes mid-elevation tree skiing that typically feels like a safer alternative to more exposed faces. Below 2,000′ is it less likely as there is a supportable crust. Triggering an avalanche on a wind slab also has the potential to cause a persistent slab to release. It is uncertain how sensitive this layer is to being triggered, and an avalanche releasing on this layer could be large and run further than expected. Red flags such as cracking, collapsing, and whumphfing sounds are all great indicators that the slope is capable of avalanching, however, there may be no evidence until an avalanche occurs. These types of problems can be triggered remotely, meaning that the slope above or adjacent to you may avalanche.  To avoid this problem, choose terrain with slopes lower than 30 degrees which will allow this weak layer more time to stabilize.

Large avalanche on Butch Mtn that likely failed on the buried Jan weak layer on Feb 22. Photo by Hannah Smith 2.25.2024

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 a week since glide avalanches were observed in Summit. That being said it still possible that glide cracks which look like “brown frowns” 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.

 

Weather
Fri, March 1st, 2024
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.