Seward & Southern Kenai Mtns

Archives
Issued
Fri, March 15th, 2024 - 7:00AM
Expires
Sat, March 16th, 2024 - 7:00AM
Forecaster
Mik Dalpes
Conditions Summary

Weekend Avalanche Outlook

Saturday, March 16 – Sunday, March 17

Bottom Line: With a warm spring storm headed towards the Kenai, which is forecast to bring 6 to 10″ of new snow and some wind in the alpine, avalanches in freshly windblown snow are our primary concern this weekend. These avalanches will be larger and more sensitive to trigger in the upper elevations and could be 6″ to 2′ deep. With warm temperatures and wet snow on the way, watch for wet snow slides and avoid overhead cornices. Additionally, we think there is still a chance a person could trigger a large avalanche on a buried weak layer in the Carter/Crescent Lake area. This problem can be completely avoided by sticking to slopes less than 30 degrees.

Roof avalanches: With a warm storm coming in that could bring a mix of rain and snow to sea level be on the lookout for roof avalanches. Many roofs have lingering snow from recent storms and the rain could be the tipping point. Look up when passing through doorways and keep an eye on children and pets.

Special Announcements

Turnagain Pass Avalanche Awareness Day – Saturday, March 23!
Swing by the Turnagain motorized parking lot between noon and 4pm to grab a hotdog, practice your beacons skills, chat with the forecast team, and possibly test out a demo snowmachine provided by local dealers.

Recent Avalanches

Recent Avalanches: Three natural slab avalanches were observed yesterday, March 14 in the Lost Lake area following this week’s storm cycle. They were small new snow avalanches on north and south aspects. There were a few larger natural slab avalanches observed on Marathon (east and south aspects) and Bear Mountain (north aspects) that were also likely new snow. The mountains closer to the coast received quite a bit more snow from the storm this week than the Lost Lake area, which accounts for the larger size of the avalanches. I saw two cornice fall avalanches yesterday that were both west facing. Widespread loose snow avalanches also occurred this week on aspects facing the sun that were triggered close to rocks and vegetation.

Weather Recap: Another stormy week has passed bringing 14″ of new snow and 1.2″ of snow water equivalent (SWE) to the Grouse Creek weather station at Mile 12 since last Friday, March 8. It was a relatively cold week with average temperatures below freezing bringing snow to sea level for the majority of the week although it did rain below 500′ briefly on Tuesday, March 12. The winds blew from the north this week, but not too hard, averaging in the single digits and low teens mph at the Seward airport.

Weather Outlook: A warm storm is heading towards the Kenai that looks to be on the lighter side for wind and precipitation totals. High clouds have moved in from the south as of Friday afternoon. The mountains should start seeing some light snow late Friday evening as temperatures in the Lost Lake area drop into the low 20’s F. 4 to 6″ of new snow is forecast on Saturday with temperatures rising to 32 degrees F by the afternoon at Lost Lake. Rain line on Saturday could be as high as 1,600′ potentially dropping by a few hundred feet on Sunday, but temperatures look to remain close to freezing through the weekend. Snow should continue to fall on Sunday with another 2 to 4″ expected. Temperatures in the town of Seward could reach as high as 36 degrees F on Saturday and Sunday. Ridgetop winds are forecast out of the east on Saturday increasing to 15 to 20 mph throughout the day. Ridgetop winds should shift on Sunday to southeast at 15 to 20 mph. Next week is forecast to feel like spring, the sun should come out and temperatures should climb above freezing at sea level.

Small natural avalanche on the north side of Mt. Ascension above Lost Lake. 3.14.2024

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

With 6 to 10″ of new snow forecast by Sunday evening and ridgetop winds blowing 15 to 20 mph from the east, wind slabs are the primary concern this weekend. The winds don’t look terribly strong so this may only be a problem in the alpine areas above 2,500′. Wind slabs this weekend could be 6″ to 2′ deep depending on the storm totals and strength of the wind. Watch for blowing snow off ridgelines and across gully features. The natural avalanche pictured below is a great example of a cross-loaded gully that avalanched after the storm this week. Riding or jumping on a test slope is a good way to assess how a wind loaded slope is adjusting to its new load. A shooting crack indicates the snow is not yet bonding well to the surface below and that slope will need some time to adjust. Wind slabs generally take 24 to 48 hours to stabilize.

Wet loose avalanches: Wet snow and warm temperatures means wet loose avalanches also known as “point release” will be on our radar especially if the sun comes out. Look for roller balls as an indicator that a wet loose avalanche is possible. These wet snow avalanches are hard to manage if caught so we recommend finding a colder aspect to avoid this problem.

Cornice Fall: A few cornice falls were observed this week on west facing aspects that get baked in the sun in the afternoons. Temperatures this weekend look warm so we recommend staying out from under cornices especially if the sun comes out.

Peak 5,309′ located just west of Mt. Adair in the Lost Lake area with a cross-loaded gully that recently avalanched. Arrows indicate wind direction causing the slope to be loaded just beyond the arrows. 3.14.2024

Cornice fall on a southwest facing slope east of Resurrection Bay. 3.14.2024

 

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/Crescent Lake area we think there is still a chance a person could trigger a large avalanche on a buried weak layer. We have some uncertainty about this because we don’t have recent information from this location. Last Thursday a few of our forecasters were in the Carter/Crescent Lake area and observed recent avalanche activity on all aspects that looked persistent in nature (deeper crowns than a new snow avalanche or they stepped down). The snowpack in this location tends to resemble Summit Pass, it is thinner than the Lost Lake area and harbors more weak layers as a result. If you head to Carter/Crescent Lake the only way to assess for this problem is to dig a snowpit to see if the structure exists where a strong layer of more cohesive snow “slab” sits over a weak layer (less cohesive snow). A stable pit result doesn’t mean you won’t trigger an avalanche because this problem has a tendency to cause “surprise” avalanches that occur without any “red flags” (recent avalanches, whumpfing, shooting cracks). Places where the snowpack is thin tend to be trigger spots so if you are getting into steep terrain we recommend avoiding rocky areas. The way to completely avoid this problem is to stick to slopes less than 30 degrees.

Weather
Fri, March 15th, 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.