Turnagain Pass

Triggering a wet avalanche is possible today where rain has saturated the snowpack in the mid and lower elevations. Daytime temperatures are expected to rise into the mid-40F’s in the lower elevations and mid-30F’s to 2500’. Today’s forecast is calling for scattered rain showers (0.15” of rain) below 2300’. As instability showers move through our region, patches of blue sky and sun are also possible at times. Today’s avalanche danger will depend on how warm it gets and if radiation from the sun impacts the snow. Even a little sun shining through thin cloud cover can create rapid warming of the snowpack. Expect surface snow to be wet and ’pushable’ in the mid elevations. Areas like Portage and Girdwood Valley that received more rain in the last few days, there is more potential for a wet avalanche to entrain deeper into the snowpack, and larger avalanches are possible. If the sun heats up dry snow in the upper elevations, natural wet snow avalanches could release naturally, especially near rocks or where chunks of cornice are shedding. Pay attention to how wet and saturated the snow feels. Is this the top 2 or 3” of wet snow or a deeper issue? If your skis or snowmachine start punching deeper into the snowpack, avoid all steep slopes. Triggering a wet avalanche, once it’s picked up momentum, can be difficult to manage. 

Water totals (inches of rain) in the last two days. New snow in the upper elevation since Tuesday could range from 1 to 3 feet (Turnagain Pass vs. Girdwood)  

• Turnagain Pass:   0.5”    (1.6” total since Saturday)  
• Girdwood Valley:  1.2”    (2.8” total  since Saturday)
• Portage Valley:     2.4”    (7.4” total since Saturday)
• Summit Lake:       0.1”    (0.3” total since Saturday)

Slopes above Byron Glacier trail have seen a lot of avalanche activity this week. Note the large cornice that still looms above, and rocks that can easily heat-up and shed snow with daily warming and sun.  

Visibility was limited yesterday, but we did see a few new natural wet loose avalanches on Seattle Ridge. This aspect has seen a lot of wet avalanche activity this season, but it doesn’t mean this aspect is done. Human triggered avalanches are still possible. Monitor how wet and saturated the snow is and how it changes throughout the day. 

If you are heading out to catch new snow at higher elevations, extra caution is warranted where little information exists about how well the snowpack is adjusting. Storm slabs that formed on Tuesday due to heavy snow and strong winds could range from 1 to 3 feet deep depending on what part of the forecast zone you are in. Expect storm slabs to be deeper in Portage Valley and Girdwood. Any sun on solar heating could make them easier to trigger in the afternoon.  Evaluate snow and terrain carefully and ease into steep slopes with caution. Also be aware of slopes that suddenly change from drier snow in the upper elevation to wetter snow mid elevation.  

Upper elevation North aspects: Shaded aspects in the Alpine had a thin layer of facets and/or surface hoar over a crust under last week’s new snow. This layer may still be lurking, which could result in slab avalanches 2 – 4+’ thick composed of couple of storm layers of snow.   

Warm and stormy weather this week has caused cornices to shed. There are some places, like Seattle Ridge where Cornices are large and challenging to judge if you are on them. Give them plenty of space and avoid being under cornices. Daily warming and any sun that might appear today will be adding additional stress. 

A brief clearing yesterday afternoon showed recent cornice fall below CFR on Tincan ~2400′.