Turnagain Pass

One small slab avalanche was reported in the forecast area yesterday.

Tincan’s Hippy Bowl: A skier/snowboarder triggered a small soft slab avalanche failing at the new/old snow interface, possibly on a sun crust. Slab was roughly 12-16″ deep, 30′ wide and running around 100′.

Tincan’s Hippy Bowl – Slab avalanche triggered be either a skier or snowboarder. Photo taken from Center Ridge parking lot by CNFAIC staff.

After a sunny and enjoyable break between storms, another weather system is moving in this afternoon. Clouds have already arrived and winds have switched around to the east. Light snowfall should begin this afternoon before peaking early tomorrow morning. Only an inch or so is expected by sunset, 2-4″ overnight, and another 2-4″ early in the day tomorrow (cross you fingers for a storm total close to 6-8″). Ridgetop winds are expected to slowly rise through the day and average up to 20-25mph by 4pm with stronger gusts. This will be enough to blow any soft surface snow into shallow wind slabs later today.

That said, pay attention to changing conditions. Keep an eye out for active wind loading and fresh wind slabs being formed. These are likely to be shallow and forming in the higher terrain. The usual signs of cracking in the snow around you and stiff snow over softer snow will be good clues for either finding a fresh slab or even an older one formed late last week. Those are concerning as well and discussed below in Problem #2.

Sluffs: Steep slopes with loose surface snow are sluffing easily.These can pick up enough volume and speed to carry a person. While it is unlikely they will be big enough to bury you, they can be dangerous if they drag you into terrain traps like cliffs, trees, rocks, or gullies.

Triggering a larger slab avalanche 1-3′ deep is still a concern at all elevations. Wednesday’s snow is sitting on weak layers of facets and/or surface hoar as well as a slick sun crust on steep southerly slopes. All these buried layers are keeping Wednesday’s snow from bonding quickly. Furthermore, the northwest winds on Thursday into Friday created wind slabs of variable depth. Hence, finding and triggering a slab that is either shallow or up to 3′ deep should be on our minds.

Watching for signs of instability are key. These are whumpfing (collapsing) in the snowpack, cracking in the snow around you and any recent avalanches. All these signs have been reported over the past two days. The one piece of good news is the cold temperatures seem to be weakening the slab, which limits its ability to release. Also, some snow pit tests are pointing to Wednesday’s snow beginning to bond. Nonetheless, this avalanche problem is one that can fool us by allowing several people on the slope before it avalanches or avalanching remotely, meaning triggering a slab from the top, side or below. It’s still a heads up situation that requires close evaluation of every slope. Some slopes may show good stability while the next one over does not.

Several slab avalanches were seen on the north side of Eddies ridge yesterday (3/13). Note the skier/boarder tracks above the crowns and just under the trees. It is unknown if these were triggered remotely from above or if they were natural at the end of Wednesday’s storm or from the NW winds on Thursday. Photo: Heather Johnson (more photos here).

Check out this Hat Trick photo by Andy Moderow on the SW face of Shark’s Fin. 1- glide crack, 2- natural dry loose sluffs, and 3- natural slabs from late last week. 3.13.21.