Seward & Southern Kenai Mtns

Archives
Issued
Fri, February 23rd, 2024 - 7:00AM
Expires
Sat, February 24th, 2024 - 7:00AM
Forecaster
Mik Dalpes
Conditions Summary

Weekend Avalanche Outlook

Saturday, Feb. 24 – Sunday, Feb. 25

Bottom Line: This weekend is forecast to bring a small storm on Saturday and a sunny day on Sunday accompanied by northwest wind throughout. Both Saturday and Sunday avalanches 1-2′ deep in freshly windblown snow will be likely for a human to trigger and could be big enough to bury you. We think it is unlikely that a person could trigger a weak layer buried deeper in the snowpack, but we have some uncertainty about this in areas like Carter Lake and Snug Harbor. If Sunday proves to be sunny watch for wet loose avalanches on south facing slopes and stick to other aspects to find colder snow and avoid being caught in one of these wet snow slides.

Special Announcements

Forecaster chat TODAY in Seward from 5-6pm at the Seward Community Library and Museum community room! Get stoked to talk about snow! 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.

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:  Widespread avalanche activity occurred this week in the Seward area with two very large storms passing through. The weight of the new snow, rain, and wind caused many large natural storm slab, wind slab, and loose snow avalanches. There were also some very large avalanches observed, which we think failed during the storms on the January facet layer that is now buried up to 5′ deep in some places. Most of these avalanches were observed yesterday, February 22 once the skies cleared and we could finally see the mountains.

Weather Recap: Two huge storms passed over the Kenai Peninsula this week bringing a total of 4-5″ of water or snow water equivalent (SWE) to the mountains. This came in the form of rain to at least 2,000′ and 1-2′ of snow above during the first storm that occurred Monday and Tuesday, February 19 and 20. The next storm was close on the first one’s heels coming in Wednesday afternoon, February 21 and tapering off Thursday morning, February 22. This one was colder bringing snow to sea level and another 2-3′ of snow in the alpine.

Weather Outlook: Temperatures have cooled off as of Friday morning February 23, to 24 F in Seward. Today’s weather looks quiet, sunny with light south to southwest ridgetop winds and temperatures in the Lost Lake area in the 20’s F. Clouds look to build tonight with another weak front approaching. Saturday is forecast to be cool and a bit stormy with temperatures in the low 20’s F and ridgetop winds building to 20 to 30 mph from the northwest with gusts to 45 mph. The mountains could see 2-3″ of new snow by Saturday evening. The system is forecast to move out Saturday night, but the winds should remain in that 20 to 30 mph range from the northwest through Sunday tapering off Sunday evening. Sunday looks to be sunny with temperatures in the single digits F in the morning climbing into the teens F by the afternoon.

New snow slab avalanches on Mount Alice with a big beautiful moon. Photo: Mark Dalpes 2.22.24

New snow slab avalanches on Resurrection South Peak. Photo: Mark Dalpes 2.22.24

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

With 2-5′ of new snow in the Seward Mountains this week and a few more inches forecast there is plenty of snow to be moved around by the wind this weekend making wind slab avalanches our primary concern. Wind slabs 1-2′ deep will be likely and easy for a person to trigger in places that have been recently loaded. Wind slabs tend to form below ridgelines, on cross-loaded gully features, and on steep rolls. Watch for blowing snow and avoid those places where it is depositing. Wind slabs may feel firm or sound hollow and if you poke your pole or probe in them there will be stiffer snow over softer snow. You can dig a quick hand pit or jump on a small test slope to see how the slab is bonding to the snow beneath. Shooting cracks and whumpfs are clear signs of unstable snow.

Wet loose avalanches: The sun is forecast to come out on Sunday, which could cause some wet loose avalanches especially on steep south facing slopes with alders or rocks poking through the snow. It looks like it will be cool and windy, which can help keep this from happening, but keep your eyes out for “roller balls” or wet balls of snow rolling down the slope. Roller balls are early signs of wet loose avalanches which have a lot of weight to them and can be difficult to escape if you find yourself caught.

Wind blowing off Callisto Peak south of the Seward Zone. Winds this weekend are forecast to come from a similar direction. Photo 2.22.2024

Wet avalanche debris on the east face of Mount Marathon. This slide probably released during the warmer storm on Tuesday Feb. 20. The debris crosses the “Jeep Trail” that passes underneath these large slide paths. Photo 2.21.2024

Here is a close-up view of the debris running over the trail and into the large trees on the right of the photo. Photo submitted anonymously, 2.21.2024

 

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

The January facet weak layer we keep talking about is now buried 2-5′ deep in the Seward area. This layer is showing signs that it is strengthening, and we think it is unlikely that the weight of a human would be enough to trigger an avalanche on this layer. Several avalanches were observed after the most recent storm that we believe failed on this layer and they are located in specific places underneath rock bands with steep slopes above.

We have some uncertainty about this in some places because we haven’t been to Carter Lake or Snug Harbor in a couple of weeks. With the recent warm temperatures, we think this layer is strengthening throughout the zone, but the only way to assess this problem is to dig a snowpit and perform stability tests. If you find a layer of more cohesive snow over a layer of weak sugary snow that is a sign of poor structure regardless of test results. It is also important to know that this type of avalanche may not produce any warning signs before releasing. To completely avoid this problem stick to slopes less than 30 degrees.

Large slab underneath rockband that is likely a “persistent slab” avalanche failing on the January facet weak layer. Photo 2.22.24

Weather
Fri, February 23rd, 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

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