Turnagain Pass

Although not a lot of traffic has been out in the wet weather, a motorized Level 2 course did see a recent natural slab avalanche yesterday on the frontside of Seattle Ridge, north of the common uptrack (photo below). Crown reported to be around 1,200′ in elevation. Note how the winds have cross loaded the gullies in the photo and how the avalanche released mid-slope. The slab may have released in weak snow from January, but that is unconfirmed. Otherwise, no avalanches have been seen or reported during the past few days.

Recent natural slab avalanche mid-slope on Seattle Ridge, just north of the motorzied uptrack. Thanks to the AAS motorized Level 2 course for the photo, taken on 2.19.24.

A warm storm ramped up last night and should peak today. Rain is falling as high as 1,500′ to 2,000′ this morning and should creep slightly higher before cooling tomorrow. Check out the precipitation graphic below. It shows around 1-1.5″ of rain in Girdwood and 2 to 3″ in Portage and Seward. This equates to 1-1.5′ and up to 3′ of snow in the high elevations respectively. Turnagain, Summit, and Moose Pass’s look to be on the drier side with only .5 to 1″ of rain (5-10″ of snow above 2,500′).

The east ridgetop winds that have been relentless for a week are currently blowing 25-40 mph with gusts near 70 and could increase even more later today. All this weather talk leaves us with increasing avalanche danger. Wet avalanches are likely at the mid and lower elevations while dry snow avalanches are likely in the higher elevations.

Wet Avalanches up to 2,500′:  Rain falling on snow up to 2,000′ and wet snow up to around 2,500′ can cause both wet loose and wet slab avalanches. Wet slabs between 1 and 3 feet deep are likely due to that layer of faceted snow from January buried 1-3′ deep. As the surface layers saturate that older weak layer can fail resulting in a wet/moist snow slab. This could have played a role in the avalanche seen yesterday on Seattle Ridge. Simply put, wet avalanche are a concern and unmanageable.

Dry Avalanches above 2,500′:  See below in Problem 2.

Rainfall expected at the lower elevations from 3am this morning until 3am tomorrow (Wed). Thanks to our friends at the NWS for producing these graphics. Find them HERE. 

Dry snow avalanches in the form of wind slabs and storm slabs are likely occurring in the higher elevations due to new snow and strong wind. This issue is most pronounced in Girdwood, Placer, and Portage Valleys where much higher snowfall amounts are expected. Check out the graphic below of the differences in snowfall expected. The higher the snowfall the more dangerous the avalanche conditions.

Persistent Slab Avalanches:  With a known layer of faceted snow buried 1-3′ deep, we can expect to see avalanches breaking deeper than our typical wind slabs per say. There is a lot of uncertainty as to how this layer will react in the higher elevations with another round of wind and snow. But either way, it’s storming out and it’s best to let the mountains do their thing before we venture into any type of avalanche terrain.

Snowfall expected from 3am this morning until 3am tomorrow (Wed). Thanks to our friends at the NWS for producing these graphics. Find them HERE.