Seward & Southern Kenai Mtns

Archives
Issued
Fri, February 16th, 2024 - 7:00AM
Expires
Sat, February 17th, 2024 - 7:00AM
Forecaster
Andrew Schauer
Conditions Summary

Weekend Avalanche Outlook

Saturday, Feb. 17 – Sunday, Feb. 18

Bottom Line: The main concern going into this weekend is the potential for triggering an avalanche where the wind is blowing snow into sensitive slabs. A few inches of snow will add a little more slab-building material, increasing the chances of triggering an avalanche. A person may also trigger a larger avalanche failing on a weak layer of snow around 2 feet deep, especially in the northern end of the Seward zone near Snug Harbor and Carter Lake. Both of these problems can be avoided entirely by sticking to low angle terrain, but if you are considering stepping out into steeper slopes it will be important to take the time to carefully assess the snowpack first.

Special Announcements

Summit Lake Avalanche Accident:  An avalanche was triggered on Tuesday February 13th by a group of three backcountry skiers on John Mtn. Two of the three people involved sustained injuries and the third did not survive. Our deepest condolences go out to the friends and family of the deceased. A preliminary accident report is available here and we will publish a full report by the end of next week.

Forecaster chat next Friday, February 23 from 5-6pm at the Seward Community Library and Museum community room. Come chat with us about the product we are producing called the “Weekend Avalanche Outlook,” and the state of the snowpack in Summit and Seward. We can also answer other questions you may have. More info Here.

Recent Avalanches

Recent Avalanches:  Heavy snow followed by a very strong and persistent wind event led to an impressive cycle in the Seward zone this week. There were multiple massive natural avalanches at high elevations that likely occurred in the first part of the week but were observed when skies began to clear in the middle of the week. Most of this activity was concentrated closer to the coast, but we also saw some big avalanches at upper elevations in the Lost Lake elevation on Resurrection North. These likely resulted from the combination of very active weather adding a huge load to the weak layer of snow that formed during the January dry spell.

We also began to see natural wet loose avalanches as temperatures rose later in the week. These were happening on steep southerly slopes, and occasionally pulling out small slabs below rock bands.

Weather Recap: Last weekend’s storm delivered 2+ feet of snow to the mountains around Seward from Saturday through Monday, with occasional rain making it up to around 1500′. The snow was immediately followed by the strong easterly winds that have been impacting the broader region, and upper elevations have likely seen sustained winds of 30+ mph with gusts of at least 50 mph or stronger since Tuesday. Skies have been mostly clear and temperatures have been getting into the low to mid 40s F during the day and just barely below freezing at night since Wednesday.

Weather Outlook: The high pressure system that has been driving the windy and warm weather this week is expected to move out this weekend, and chances for snow will increase as the pattern changes. For this weekend we will most likely only see a few inches of snow, but we may see 2 feet or more during the middle of the week. Winds are finally looking to ease at least a little bit starting Saturday morning, and are expected to average around 10 to 20 mph with gusts of 20 to 30 mph through the weekend. High temperatures should be in the mid to upper 30s F during the day, with lows in the upper 20s to low 30s F at night. Skies will most likely be cloudy this weekend.

Very large avalanche seen from Seward on Thursday, 02.15.2024.

Another big avalanche in the alpine seen from Seward, 02.15.2024

Small wet loose avalanches in the Lost Lake area. 02.15.2024

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

You probably don’t need to read this week’s outlook to know that it has been a windy week for Southcentral Alaska. We’ve seen relentless easterly winds since Tuesday, and although the are expected to back down a bit this weekend, they will still have the potential to be blowing snow into reactive slabs that may produce avalanches.

Snowfall is expected to pick up next week, but with less than 6″ expected this weekend the most dangerous conditions will be found in wind-loaded terrain. Expect to find unstable snow in the typical wind slab habitat for the next few days– places like steep slopes just below ridgelines, steep convex rolls, and cross-loaded gullies. You can use small test slopes to assess just how reactive the snow at the surface is, and you can gain a lot of information by simply hopping off your snowmachine or stepping off the skin track to see how the snow feels. If you’re noticing stiffer, punchy snow at the surface sitting on top of softer, weaker snow, you can bet you’ve found a potentially dangerous setup. On the other hand, if you’re noticing soft snow on the surface that hasn’t been blown around by the winds, things might be relatively safe. Warning signs like shooting cracks or collapsing are clear signs of a dangerous setup that will likely produce an avalanche.

The wildcard is the persistent problem mentioned in Problem 2 below. That layer exists through most of the rest of our forecast zones, and although it is less likely to make a big avalanche in the Seward area, we cannot rule it out entirely.

Expect to see another dramatic change in conditions in the middle of the week. It is looking like there is a good chance for heavy snowfall this week, with several feet possible by the end of the week. Avalanche danger will rise as the snowfall intensifies, and large natural and human-triggered avalanches will become likely on all steep slopes.

This large slab avalanche on a southeast slope on Resurrection North Peak was likely a result of the combination of heavy wind loading on top of a weak layer of snow. With a little bit of snow and more wind on the way, similar activity is possible this weekend. 02.15.2024

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

As we mentioned last week, the January dry spell formed a weak layer of facets that is now buried 1-2 feet deep. This was the layer responsible for the fatal avalanche accident in the Summit Lake area on Tuesday, and it also exists in the Seward area. From what we have seen so far, this layer is not quite as concerning in the Seward area as it is elsewhere. However, there are a few very important caveats:

  • The northern end of the Seward zone is potentially more similar to the Summit area, and thus more dangerous. Mik found the facets to be weaker and more developed in Carter Lake when she was there last week, and we suspect that may also be the case around Snug Harbor.
  • We don’t know whether those big avalanches we saw near the coast this week were a result of the January facet layer or just a result of the continued strong winds, but we have a feeling it is a combination of the two. Some slopes in the high alpine are still in the midst of a major loading event with these strong winds, and you may be able to trigger an avalanche up high as the winds continue into the weekend.

This is a tricky problem to assess. For the Seward zone, we think the chances of triggering an avalanche on this layer are much lower than our other zones, but we can’t rule it out entirely. You can completely avoid this problem by sticking to lower angle slopes and letting the layer gain a little more strength. If you are trying to get into steeper terrain, the only way to really assess this layer is to take the time to dig a pit and test the layer. As always, pay attention to red flags (cracking, collapsing, and other avalanche activity) since these are clear signs of unstable snow. But keep in mind, persistent weak layers like this have a nasty habit of getting people caught in avalanches without giving any kind of warning signs.

Weather
Fri, February 16th, 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
Riding Areas

The riding areas page has moved. Please click here & update your bookmarks.


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