Turnagain Pass

Wet Loose: Spring is here and with it comes daily fluctuations in the avalanche danger with sun and warming. Timing is everything. Clear skies overnight have created a surface crust adding strength to the snow. As the day heats up and the crust melts and loses strength, the danger rises – making it possible to trigger a wet avalanche on steep sun exposed terrain features. Today looks similar to yesterday with daily temperatures expected to reach the mid-40F’s by early afternoon and little to no wind. Remember solar noon is around 2pm  and this is when wet avalanches can begin to release, either naturally or by a person. Once the snow becomes wet and ‘mushy’ and your skis or snowmachine start trenching into wet snow, it’s time to find supportable surfaces. Even a small wet avalanche can turn into something larger in bigger terrain.

Wet Slab: There remains some uncertainty around the possibility of triggering a wet slab avalanche as warm temps today make the snow wet in the mid elevations. Earlier this week many natural wet loose and wet slab avalanches occurred below 2000′ where rain saturated the snowpack. As water drains out of the snow and we experience several days of re-freezing overnight this is becoming less likely, but not out of the question.

Cornices: Daily warming and sunnier weather can make cornices more unstable. As always, give cornices plenty of space and limit exposure underneath them.

Widespread natural wet avalanche cycle occurred below 3000′ throughout our region. Note the wet slab at 1500′ on South face of Tincan. 

Pay attention to how supportable the snow feels in the afternoon as surface crust melt and the snow becomes wet. Yesterday it was easy to post hole up to your waist on Southerly aspect below 2000′. 

Most of the large wet avalanche from 4/10-4/11 on Seattle Ridge were on the Southern end of Turnagain Pass where a generally thinner snowpack exists. Some of these avalanches released near the ground. 

Triggering a lingering storm slab or a persistent slab is becoming less likely with time. However afternoon warming adds an element of uncertainty as surface crusts break down and destabilize the snow on solar aspects. Yesterday a group of 3 skiers experienced a collapse (whumpf) at 3000’ on a SW aspect of Tincan, and the day before a skier triggered a storm slab on a West aspect of Johnson Pass near 4900’. We know of older weak snow (facets) buried within the top 2’ of the snowpack and we don’t have a lot of info about how this snow is adjusting in the upper elevations. Northerly aspects with dry snow (without a surface crust) may harbor this set up. Basically triggering slab avalanche 1-2’ deep should still be on your mind if venturing into steeper terrain in upper elevations.