Seward & Southern Kenai Mtns

Archives
Issued
Fri, April 12th, 2024 - 7:00AM
Expires
Sat, April 13th, 2024 - 7:00AM
Forecaster
Mik Dalpes
Conditions Summary

Weekend Avalanche Outlook

Saturday, April 13 – Sunday, April 14

Bottom Line: Finally, spring like weather is in store for the Seward area mountains. With a forecast for temperatures in the 30s F in the mountains and sunny skies we expect wet snow avalanches to be the primary concern through the weekend. Look for roller balls as an indication the snow is heating up and choose a different aspect for colder snow conditions. Additionally, on colder and shadier aspects especially in the upper elevations there are some dry snow problems. Northwest winds are forecast to blow just strong enough to form wind slab avalanches 6″ to 1′ deep. Watch for blowing snow on ridgelines and across gully features and avoid places where the snow is being deposited. Natural and human triggered dry loose avalanches were reported this week, watch for this type of avalanche on north facing slopes. We recommend managing your sluff to avoid getting caught up in this problem.

Special Announcements

Avalanche Center End of Season Operations: Next Friday, April 19 will be the last “Weekend Avalanche Outlook” for the season. After that we will post some “spring tips” which will be our last post before the first product next season.

Recent Avalanches

Recent Avalanches: All of the avalanches observed this week were reported on Wednesday, April 10. There were a few large old wind slabs observed on north facing slopes in the Lost Lake area likely from south wind that occurred earlier this week. There was some new wet loose activity on east, south and southwest facing slopes both in the Lost Lake area and in the coastal mountains that occurred on Wednesday, April 10 when the sun was out in full force. There were also a few natural and skier triggered dry loose avalanches on north facing slopes reported in the Snug Harbor area of Lost Lake and the north side of Mount Marathon. Lastly, I saw at least three recent slab avalanches on the north side of Mount Ascension at about 3,000′ that looked deeper than the 6″ of storm snow the area received on Tuesday, April 9. It seems most likely these are deeper as a result of shedding from above with strong south winds during the storm.

Weather Recap: Winter is hanging in there on the Kenai Peninsula. It was a relatively cold week considering it is April and technically spring. Average daytime temperatures at the Cooper Lake weather station at 1,200′ were in the upper 20s to low 30s F with highs occasionally reaching 40 F and a hard freeze occurring each night. This week alternated between sunny days and cold storms bringing a total of 10″ of new snow and 1.2″ of “snow water equivalent” (SWE) to the Grouse Creek weather station (700′) at Mile 12. Reports indicate there were much greater snow totals closer to the coast and in the upper elevations. Most of this snow arrived on Tuesday, April 9 which was accompanied by strong south winds. Winds were otherwise mostly out of the north occasionally strong enough to move some snow around up high.

Weather Forecast: The weather looks fairly mild this weekend with no precipitation in the forecast. High temperatures look to be in the mid 30s F at Lost Lake on Saturday with ridgetop winds from the north at 5 to 10 mph possibly gusting to 20 mph in the late afternoon/evening. Saturday may start out with some clouds, but they look to clear out by the afternoon. Sunday is looking to be sunny with temperatures climbing into the upper 30s F and ridgetop winds from the northwest at 10 to 15 mph. The town of Seward will likely see 40 degrees F or a bit higher both days and nighttime temperatures should drop into the 20s F through the weekend. The north winds are forecast to be a bit stronger in the town of Seward than they are on the ridgetops in the Lost Lake area. The sun is forecast to stick around through Monday next week with possibly a warm wet storm coming after that.

Old debris and fresh slab avalanche on the north side of Mt. Ascension at about 3,000′. 04.10.2024

 

Avalanche Problem 1
  • Wet Loose
    Wet Loose
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
More info at Avalanche.org

With the sun forecast to come out by Saturday afternoon wet loose avalanches will be our primary concern this weekend. These are especially likely to be triggered near rocks and vegetation which are attracting heat. These avalanches will likely be small at upper elevations but could grow larger in size as they reach lower elevations where higher temperatures are warming the snow deeper into the snowpack. There is some wind forecast this weekend which may help to keep the surface of the snow cooler and if that is the case we may see less activity than we would expect from a bright sunny day. Roller balls are a sign that the snow surface is warming up and natural wet loose avalanches are on the way. Another good test for this type of problem is to step off your machine, board, or ski and see how far your boot penetrates into the snow. If you sink to your ankle in wet looking snow it’s time to find a colder aspect.

Cornice fall: With warm temperatures and hot sun shining on the slopes cornice fall is possible. Watch for these looming chunks of snow and avoid being underneath them. Cornices are known for their tendency to break back further then you might expect so we recommend giving them a wide berth when travelling above them.

Wet loose avalanche activity on the south facing slopes of Mt. Eva and a cornice on the ridge on the left side of the photo. Photo by Heather Thamm, 04.10.2024

 

Avalanche Problem 2
  • 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

The northwest wind is forecast to be blowing this weekend beginning Friday night, April 12 which will likely be creating some fresh wind slabs 6″ to 1′ deep. Observations indicate there is quite a bit of soft snow available to be moved around by the wind in the upper elevations and especially on the north aspects that are not forming a sun crust. The ridgetop wind speeds on Saturday look just barely strong enough to move snow at 10 mph. Sunday’s ridgetop wind speeds are forecast a bit higher at 10 to 15 mph. The likelihood of this problem is going to depend on how much snow gets moved by the wind. Watch for recent avalanches and blowing snow off ridgelines and across gully features. Watch for stiffer snow over softer snow as a sign of a wind slab and a shooting crack means the conditions are unstable. Riding or jumping on a test slope or digging a hand pit are great ways to assess how well a slab is bonding to the snow beneath.

Dry Loose: Both natural and skier triggered dry loose avalanches (also known as “sluffs”) on north aspects have been reported this week and will be possible this weekend especially in the upper elevations where more snow accumulated during the storm on Tuesday, April 9. We recommend managing your sluff to keep from getting caught up in this type of problem. One way to do this is to ride off to the side of the slope and let the sluff pass.

Wind slab just below red line covered in a few inches of fresh snow on a north aspect in the Snug Harbor area. Blue line indicates a natural dry loose avalanche. Photo by Evan Kreps, 04.10.2024

Weather
Fri, April 12th, 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.