Seward & Southern Kenai Mtns

Archives
Issued
Fri, March 29th, 2024 - 7:00AM
Expires
Sat, March 30th, 2024 - 7:00AM
Forecaster
Mik Dalpes
Conditions Summary

Weekend Avalanche Outlook

Saturday, March 30 – Sunday, March 31

Bottom Line: A storm has arrived to the Kenai Mountains which is forecast to bring up to 15″ of new snow by Saturday night accompanied by southeast winds making natural avalanches in fresh and windblown snow possible and human triggered avalanches likely above 1,500′. Heavy rain could fall up to 1,500′ making natural wet avalanches likely in the lower elevations. If the forecast verifies and the avalanche conditions become sensitive these problems can be completely avoided by sticking to slopes less than 30 degrees.

Special Announcements

Avalanche Forecast Survey: Simon Fraser University is collaborating with US avalanche centers to better understand how useful avalanche forecast information is for trip planning. This research will help drive development of future avalanche forecast products. Click here if you are interested in participating in a 20 minute survey.

Recent Avalanches

Recent Avalanches: The most significant avalanche reported in the last week was a wet slab observed yesterday, March 28 in the afternoon on an east aspect of Bear Mountain (located in Seward) at about 1,500′. There was a cornice fall triggered wind slab reported near V-Max which likely occurred on Monday, March 25 during a small storm event. There was widespread dry loose activity this week above 3,000′ and wet loose activity below 3,000′ on all aspects.

Weather Recap: It was a mostly cloudy week in the Seward Zone with a few inches of snow above 1,500′ and 0.4″ of rain below that. Temperatures averaged in the 30s F with highs in the low 40s F. There were 5 nights in a row last week that temperatures never dipped below freezing at the Grouse Creek weather station at 700′.

Weather Forecast: It looks like winter is back for at least a few days, maybe longer. It is snowing at sea level in the town of Seward as of Friday afternoon March 29 and winds are blowing from the south at 15 to 20 mph gusting in the 30s at the Seward Airport. The mountains could see up to 3″ of new snow by Friday evening. Temperatures should warm slightly this afternoon and the precipitation could switch to rain by this evening with rain line creeping up to 500′. Another pulse of moisture is forecast to arrive in the early morning hours of Saturday bringing 6 to 12″ of new snow to the upper elevations and rain below 1,500′. Ridgetop winds are forecast to be 15 to 20 mph from the southeast gusting to 40 mph. Temperatures should cool into the 20s F as the storm moves out Saturday night. Temperatures on Sunday look to climb back to the mid 30s F and a few snow or rain showers might linger with ridgetop winds in the 5 to 10 mph range gusting to 20 mph. The sun might also poke out on Sunday before another cold storm arrives Sunday evening bringing snow and light southeast winds.

Cornice triggered wind slab near V-Max, Snug Harbor area likely March 25. Red lines indicate cornice location, blue lines indicate crown of wind slab. Photo: Evan Kreps 03.26.2024

Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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

The current series of storms could bring up to 15″ of new snow to the mountains by Saturday evening accompanied by southeast wind making both storm and wind slabs our primary concern. If the forecast verifies, natural storm and wind slabs will be possible and human triggered avalanches will be likely. In sheltered areas where 10 to 12″ of snow has accumulated, we could find storm slabs and in exposed areas we could find wind slabs 1 to 2′ deep.

Luckily these problems are some of the easier ones to assess. Look for blowing snow off ridgelines and across gully features. Wind slabs can sound hollow and will feel like stiffer snow over softer snow if you poke with your pole or probe. Jumping on a small test slope or digging a hand pit are great assessment tools for these problems that can give you an idea of how the new snow is bonding to the old snow. A whumpf or shooting crack are clear signs that the snowpack needs time (up to 48 hours) to adjust to its new load. Sticking to slopes under 30 degrees is a safe bet during stormy conditions.

Forecast snowfall totals expected from 4am Saturday to 4am Sunday. Graphic courtesy of the NWS Anchorage forecast office. 03.29.2024

Avalanche Problem 2
  • Wet Slab
    Wet Slab
Wet Slab
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
More info at Avalanche.org

A wet slab avalanche was observed on Thursday afternoon, March 28 indicating the snowpack really warmed up this week with warm temperatures and sun. With rain expected in the lower elevations on Saturday and the sun potentially coming out on Sunday we expect wet avalanches to occur naturally on all aspects at elevations below 2,000′. Wet avalanches are dangerous because the snow is heavy; it can drag you down and be difficult to escape. Wet slab avalanches are hard to assess, and the consequences can be terrible. The way to completely avoid this problem is to stick to slopes less than 30 degrees and avoid being in the runout of lower elevation paths like the Mount Marathon bench trail.

Cornice Fall: Warm temperatures and sun can increase chances for natural cornice falls which can be dangerous themselves and they can also trigger slab avalanches. Look for these large looming chunks of snow and give them a wide berth as they can break back farther than we think.


Wet slab avalanche on the east side of Bear Mountain in Seward observed Thursday afternoon, March 28, 2024

Weather
Fri, March 29th, 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.