Turnagain Pass

WIND SLABS: There was 3-6” of very light weight fluffy snow on all aspects throughout our region and a few inches fell overnight with warmer temperatures. This snow combined with Easterly ridge top winds 10-20 mph overnight with gusts into the 30s may have formed tender wind slabs on leeward slopes. The snow may feel “upside down” with slightly stiffer snow over softer snow. Look for areas of pillowed or drifted snow and watch for cracking. Pay attention to active loading this morning as few more inches are forecasted to fall with continued gusts into the 30s. 

LOOSE SNOW: Sluffs may also be easy to initiate on steep features and could be fast moving.

CORNICES: Remember these unpredictable hazards can break farther back onto a ridge than expected and have the potential to trigger an avalanche on the slope below. Give cornices extra space and avoid being under them. 

GLIDE AVALANCHES: There is a new glide crack above the flats along Seattle Ridge, just looker’s left of the up-track and Repeat Offender slide path. Avoid hanging out under this crack and any others you may see – these release without warning and are very destructive.

SUNSHINE? If skies clear this afternoon be aware of solar warming that may trigger loose snow avalanches in steep Southerly aspects.   

Terrain East of Sunburst with evidence of cornice fall in the background and obvious wind patterns on the snow. 

Cross-loaded slopes and the glide crack on Seattle Ridge south of the up-track. 

Yesterday the beautiful weather and soft snow inspired a number of folks to test some of the slopes around the advisory area. There were no reports of avalanches being triggered. However, it is important to remember today that there is still poor snowpack structure in many locations and the possibility of triggering a dangerous avalanche exists if you hit the wrong spot. It’s been a week since the Valentines Day storm dumped 2-3’ of heavy snow on top of a weak surface (surface hoar and/or near surface facets). Saturday was there were two human triggered avalanches on Seattle Ridge on this set-up. The good news is with time, the weak layer has been adjusting to the slab above, making it more difficult to trigger. However the consequences remain high, meaning it is still possible to trigger an avalanche large enough to bury, injure or a kill a person. Be aware that no red flags may be present (whumphing or cracking in the snow) and the pack could have a general “it seems fine to me” feel before someone finds a trigger point. Trigger points are often where the slab is thinner, near rocks or scoured areas. Also keep in mind, these slabs can break above you, release after several tracks are on a slope and be triggered remotely. The trickiest part about our current snowpack is how difficult it is to assess due to the spacial variability of both the weak layer, the slab, and even the bed surface in some places. Some steep solar aspects (S-SE) may have a slick sun crust bed surface/buried surface hoar combo. Be aware that snow pits and stability tests may not be representative of the actual slope you are trying to assess.

Buried surface hoar in a snow pit on Sunburst yesterday at 3750′, SW aspect.

At the bottom of the snowpack are various layers of facets with varying degrees of strength. In the Summit Lake zone and some areas in Girdwood Valley and Johnson Pass depth hoar has been found as well as some areas in Turnagain Pass. Last week’s storm cycle tested these layers and only a few avalanches that we know of broke in them (Girdwood Valley, Portage and Summit Lake). These layers will be tough for people to trigger, but possible in shallow snowpack zones. The more likely case is where an avalanche occurring in the upper layers of the pack has the potential to step down and release the entire snowpack. If this does happen the volume will be large and could run long distances.