Seward & Southern Kenai Mtns

Archives
Issued
Fri, March 1st, 2024 - 7:00AM
Expires
Sat, March 2nd, 2024 - 7:00AM
Forecaster
Mik Dalpes
Conditions Summary

Weekend Avalanche Outlook

Saturday, March 2 – Sunday, March 3

Bottom Line: The relentless wind is still blowing from the north making avalanches in freshly windblown snow our primary concern this weekend. These avalanches could be 1-2′ deep and large enough to bury a person. The sun is forecast to be out in full force on Saturday so watch for signs that the snow is warming up on slopes facing the sun and choose other aspects to find colder snow and avoid being caught in a wet snow slide. There is still a chance a person could trigger a large avalanche on weak snow buried 2-5′ deep. This type of avalanche is difficult to assess and may not give any warning signs. You can avoid all of these problems by sticking to slopes less than 30 degrees.

Recent Avalanches

Recent Avalanches: The most notable avalanches in the last week were observed last Friday, February 23 in the Crescent Lake area. There were several large new snow avalanches that likely occurred during the storms last week and there was one very large avalanche that stepped down into older weak layers which is pictured under problem 2 below. This week there has been widespread wind slab activity with the strong north winds that have been blowing.

Weather Recap: It’s been a cold and windy week and today is the seventh day in a row of an outflow north wind event. Temperatures were mostly in the teens F and the Grouse Creek weather station recorded 4″ of new snow this week most of which came last weekend. It looks like things are finally going to calm down Saturday evening March 2.

Weather Outlook: It looks like a relatively calm weekend is in store. The north winds are still blowing strong as of Friday morning both in Seward and on the ridgetops, but they are forecast to calm in the Lost Lake area by Saturday morning to 10 mph from the northwest. The north winds in the town of Seward however are forecast to remain strong through Saturday evening. Saturday looks to be a cold and sunny day with temperatures in the single digits to low teens F. There is a weak front moving towards the Kenai that should bring clouds on Sunday. Temperatures should start out in the single digits F but look to warm into the teens F throughout the day. Winds should shift to the south on Sunday to 5-10 mph and light snow may begin to fall by Sunday evening. The models are showing a few inches of snow on Monday, but that is a bit far out at this point to count on a snowfall total. Looking ahead a pattern shift is forecast with several weak low-pressure systems heading towards Seward next week.

Large wind slabs on the east side of Mount Ascension above Lost Lake. Photo by Kit Barton 2.26.2024

 

 

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 north winds blowing for seven days straight wind slab is our primary concern this weekend. Winds have been primarily blowing from the northwest in the mountains, but localized winds can vary so you could find a wind slab on any aspect. Fresh wind slabs will be the easiest to trigger, could be 1-2′ deep and large enough to bury a person. An older wind slab may be a bit more stubborn to trigger and like any wind slab they may break above you. Look for recent avalanches and watch for blowing snow that is loading slopes below ridgelines, across gully features, and on convex rolls. Wind slabs tend to look smooth and “pillow-like.” They may feel firm beneath you and if you stick a pole or probe in the snow there will be a firm layer over a softer layer. With the strength of the wind this week these wind slabs could be found at treeline as well. As you climb in elevation you can ride or jump on a small test slope to see how the windblown snow is bonding to the snow beneath. A shooting crack like the one pictured below is a clear sign of unstable snow.

Loose Dry: Large loose dry avalanches (also known as sluffs and point releases) have been reported in the Turnagain Pass zone this week. Cold temperatures are causing this type of problem to occur in steep areas sheltered from the wind. Typically, this is a manageable problem, but if enough snow becomes entrained it could knock you off your feet or pull you in a direction you didn’t intend on going.

Loose Wet: This is the time of year when we can finally feel the warmth of the sun. This means the snow can also absorb the warmth even when air temperatures are cold. This is most likely to happen on steep slopes facing the sun. Roller balls are indicators that a slope is warming up but won’t always precede a loose wet avalanche. Loose wet avalanches are more difficult to manage than loose dry because they are heavier and more difficult to escape. You can avoid this by changing aspect if you notice a slope warming up.


Shooting crack as I jumped on a small steep test slope on Raven’s Ridge in the Summit Lake Zone. 2.28.2024

Snow blowing off Mount Alice from north winds on Wednesday, 2.28.2024

Loose wet avalanches on an east facing slope in the Lost Lake area on 2.15.2024

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

The warm storm that occurred on Tuesday, February 20 formed a crust that exists up to at least 2,000′ in the Seward Zone. Typically, a crust makes it more difficult for a person to trigger an avalanche on a weak layer below, but where the crust is thin or does not exist (above 2,000′) the potential is still there to trigger an avalanche on the January facets, which are now buried 2-5′ deep depending on elevation. This layer seems to be healing more quickly and is less likely to be a problem in the lost lake area than further north in the Carter/Crescent Zone and potentially Snug Harbor as well where the snowpack is more similar to Summit Lake. These persistent weak layers are very tricky to assess and often do not show any of the typical red flags like a whumpf or shooting crack before they fail. The only way to assess this problem is to dig a snowpit, but a stable result doesn’t mean you won’t trigger a surprise avalanche. The way to completely avoid this problem is to stick to slopes below 30 degrees and give this layer more time to heal.

There are several large avalanches in this photo of Mortar Mountain at Crescent Lake that likely occurred during the storm on February 21, but the arrow is pointing to where one avalanche stepped down to a persistent weak layer buried deeper in the snowpack. Photo by Heather Thamm 2.23.2024.

Weather
Fri, March 1st, 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.