Seward & Southern Kenai Mtns

Archives
Issued
Fri, March 8th, 2024 - 7:00AM
Expires
Sat, March 9th, 2024 - 7:00AM
Forecaster
Daniel Krueger
Conditions Summary

Weekend Avalanche Outlook

Saturday, March 9 – Sunday, March 10

Bottom Line: A storm arriving Saturday night will be creating sensitive wind slabs 1-2′ deep that could be triggered on steep wind loaded slopes. It also possible for a human to trigger an avalanche 1 to 3′ deep on a buried layer of weak snow in mid to upper elevations where snowpack is thinner. Additionally, wet loose avalanches are possible on steep south facing slopes. We recommend assessing terrain that may be wind loaded before committing to steeper terrain and avoiding avalanche terrain in the Carter Lake area where it is more likely for a surprise avalanche to be triggered on a buried weak layer.

Recent Avalanches

Recent Avalanches: Natural wet loose avalanches on steep south facing slopes were observed across the Seward region. We have not heard reports of new avalanches in Lost Lake or Snug Harbor so be on the lookout for recent avalanches that are red flags for unstable snow. The Carter Lake area has seen significant natural avalanches on all aspects likely occurring last week and failing on a weak layer.

Weather Recap: Over the weekend, clouds increased as a storm arrived on Monday and Tuesday bringing 5″ of new snow and northwest winds gusting 20-30 mph to the Seward and Lost Lake areas. On Wednesday, the storm dissipated bringing blues skies and spring like conditions with temperatures in the low 30’s F. Few clouds and blue skies continued on Thursday into Friday with moderate northwest winds (10 to 20 mph).

Weather Outlook: A low moving west into Prince William Sound is forecast to bring clouds, around 5″ of new snow, and moderate winds to the Seward forecast area. On Saturday expect clouds to move in, northwest winds (5 to 10 mph) gusting to 15 mph, and snow showers beginning late afternoon. Overnight Saturday could see 5″ of new snow. The storm looks to linger on Sunday bringing light snow (1 to 2″) and east winds that could pick up in the afternoon to gusts in the 20’s mph. Temperatures throughout the weekend should average between 10 to 25 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

On Saturday triggering an older wind slab 1′ deep on steep wind loaded slopes will be the main concern. This will become more concerning on Sunday as fresh wind slabs 1′ deep will be forming as the storm brings up to 5″ of new snow and moderate east winds. It is important to mention that new wind slabs on Sunday will be easier to trigger than older wind slabs on Saturday. Pay attention to changing weather over the weekend especially if you see blowing snow. Other indicators that you are traveling on a wind slab are firm snow over soft snow, and cracks shooting from underneath you. These red flags are typically found below ridges and rollovers and in cross loaded gullies. Traveling tests such pole probing, hand pits, and testing small slopes can give you valuable information on how likely wind slabs are to avalanche. On Saturday, assess slopes for sensitive wind slabs as you travel into steeper terrain. Adjust your travel plans on Sunday to a more cautious approach into steep terrain as new wind slabs will be easier to trigger.

Wet Loose: Spring conditions have arrived and with it wet loose avalanche activity has been increasing on steep south facing slopes. These can be large enough to carry a person off a cliff, into a tree, or into a terrain trap where snow can pile up and bury a person. As a slope heats up from the sun throughout the day, rollerballs and natural wet loose avalanches are great indicators that a human could trigger one of these avalanches. It is best to avoid steep sunny slopes later in the day that have been baking in the sun.

Wet Loose avalanche on a steep south facing slope likely releasing on March 6. Photo 3.6.2024

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

In the Carter Lake area, it is possible to trigger a slab avalanche 1-3′ deep on a buried weak layer of snow.  The most concerning weak layer is buried about 8″ deep that disappears around 2,400′.  Above 2,400′ the January facet layer is buried up to 3′ deep and is still capable of triggering a large avalanche. Although the January weak layer is becoming stronger in test pits, we have seen large avalanches that likely occurred on this layer in Carter Lake about a week ago. Red flags such as cracking, collapsing, and whumphfing sounds are all indicators that the slope is capable of avalanching, however, there may be no evidence until an avalanche occurs. Persistent slabs can be very difficult to assess and tend to heal slowly so it is recommended to stick to slopes under 30 degrees to allow these weak layers more time to stabilize.

This avalanche problem is more likely in the Carter Lake area because it has thinner snowpack similar to Summit Pass. If you are interested in checking out this zone, check this observation and the Summit Outlook to get a bit more info on this problem.

Multiple avalanches that likely released on a buried weak layer in the Carter Lake area. Photo 3.6.2024

Weather
Fri, March 8th, 2024

Weather Forecast Links:

NWS Point Forecast: Point forecast near Lost Lake.

NWS Avalanche Weather Guidance (AVG) forecast page: Zoom into the Anchorage bowl for special detailed winter forecast.

Windy.com Spot Forecast: Spot forecast for Lost Lake. (tip: scroll through models using the links at the bottom of the page, and change locations by clicking on the map).

Weather Stations

Grouse Creek Divide Snotel

Lost Lake Weather Station

Observations
Recent Observations for Seward & Southern Kenai Mtns
Date Region Location
04/16/24 Seward Observation: Lost Lake
04/10/24 Seward Observation: Lost Lake
04/03/24 Seward Observation: Snug Harbor
03/31/24 Seward Avalanche: Lost Lake
03/27/24 Seward Avalanche: Tiehacker Mountain
03/14/24 Seward Observation: Lost Lake via Snug Harbor
03/06/24 Seward Observation: Carter Lake
03/03/24 Seward Observation: Victor Creek, 1k – 1.6k elevation
02/29/24 Seward Observation: Carter Lake
02/26/24 Seward Avalanche: Mt Marathon
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This is a general backcountry conditions summary. This advisory does not apply to highways, railroads or operating ski areas.