Active wind loading was observed yesterday and Easterly winds were in the 20s gusting into the 40s for most of the day. Today wind slabs will be possible to trigger on steep wind loaded (both top and cross loaded) slopes. These may be 6″ to 2′ thick. It will be important to look for pillowed or drifted areas and watch for shooting cracks. These slabs may allow you get out onto them before they break. In some places fresh wind slabs are sitting on old wind slabs and more than one layer might be triggered. Avoid areas with hollow sounding snow. A skier on Monday found a cross-loaded pocket on Sunburst and triggered a small wind slab on a convex roll.
Cross-loading. Photo: National Avalanche Center
Cross loaded slopes Seattle Ridge 1.30.17
The January 26th warm storm event added 2-3′ of snow to the upper elevations and rain at lower elevations. This event overloaded a variety of weak layers in the pre-existing snowpack and caused a widespread avalanche cycle in the region. The good news is the snowpack is showing signs of adjusting to the load, the bad news is that there is still potential to trigger a persistent slab avalanche if you find the wrong spot. This can make for difficult snowpack assessment as the weak layers of concern (depth hoar, facets and buried surface hoar) are lurking anywhere from 2-4+ feet below the surface. Thicker snowpacks, as found at on the North end of the Turnagain Pass had a stronger snowpack to begin with and this has been a big factor in the area beginning to adjust quicker. This is opposed to the persisting unstable snowpack found South of Turnagain Pass and in the Girdwood Valley. The other factor to consider is potentially different snowpack depths and structure on different aspects due to the multiple wind events stripping slopes and loading slopes. Generally speaking Southerly and Easterly slopes are thicker while Westerly and Northerly are thinner. The thinner aspects even on the Northern end of Turnagain Pass have a more suspect structure with slabs resting on more developed facets. As always pay attention to signs of instability i.e. cracking, collapsing (whumpfing) and recent avalanches but be aware that they may not be present with this type of avalanche concern.
In general – this is a high consequence but low probability situation. If choosing to ride or ski the steeper terrain, we recommend using safe travel protocol, especially exposing one person at a time and grouping up in safe zones. If a large slab is triggered it may run further than expected and wrap around terrain features taking out mid-slope relative safe zones. Since the weak layers in question are fairly deep, it will likely take finding a thin spot in the slab or a big trigger to initiate an avalanche.
Snow pit @ 2200′ on the NW shoulder of Magnum. Stiff wind slab over weak faceted snow at the base of the snowpack.
Give cornices wide berth, avoid travel on slopes below them and remember they can break farther back onto the ridge than expected. If cornices do break and fall they could trigger an avalanche on the slope below.
Yesterday was cloudy and there was very light snow/rain showers on and off throughout the day (depending on location and elevation). Easterly winds were in the 20s and gusted into the 40s. Temperatures were in the 30s below 1000′ and mid to low 20s towards ridge tops. There was slight cooling overnight.
There is a chance of snow showers this morning with an overall clearing trend forecasted for this afternoon into the evening. Temperatures will 20s at upper elevations and 30s at sea level. Winds will start easterly 5-15 mph and shift to the North and may bump up with the outflow this evening. The weather for the remainder of the week looks to be dominated by blocking pattern that will bring sunny skies and cooler temperatures into the weekend.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||32||trace||0||57|
|Summit Lake (1400′)||28||1||.1||25|
|Alyeska Mid (1700′)||30||2||.1||51|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||24||SE||15||30|
|05/06/20||Turnagain||Avalanche: Pastoral Peak, north face||Andy Duenow|
|04/10/20||Turnagain||Avalanche: Wolverine||Mike Records|
|04/10/20||Turnagain||Observation: Eddies lookers right shoulder||Matt Yoder|
|04/09/20||Turnagain||Observation: Bench Peak||Mike Records|
|04/04/20||Turnagain||Observation: Pete’s North||Anonymous|
|03/26/20||Turnagain||Avalanche: Tincan – Proper (SW facing)||CNFAIC Staff|
|03/26/20||Turnagain||Avalanche: Seattle Ridge||W Wagner Forecaster|
|03/25/20||Turnagain||Avalanche: Sunburst Uptrack @ 2000′||J. Boisvert|
|03/24/20||Turnagain||Observation: Turnagain – Road Observations||W Wagner Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.