Quick report
- Red Flags
- Recent Avalanches, Wind Loading, Cracking
- Red Flags Comment
- <p>I did observe a skier remotely trigger an small wind slab avalanche from a ridgeline (or maybe they dropped a small cornice on the slope? I was a little too far away to tell for sure). The avalanche happened in a steep, rocky, north facing chute at just over 10,000' at the top of Cardiff Fork, on a run called Power Outage. The initial slide broke out about 12" deep, 30' wide, and ran a few hundred feet. It also sympathetically triggered two smaller wind slabs in adjacent steep rocky chutes. While this sounds like it must have been super scary/touchy out there today, this terrain is oriented in a way that it was getting nuked by wind all morning. Outside of steep, upper elevation, north facing terrain I found a number of wind slabs 1 to 4" deep that would crack under my weight, but not much more than that.</p>
Snowpack
- Instability Comment
- <p>The wind was loading exposed, north facing terrain all day today, and cross loading other features to a significantly lesser extent. The graupel on the snow surface is quite weak, and any wind slabs that form on top of this graupel will probably be touchy. With some more snow and wind in the forecast for tomorrow I would expect this danger to increase, we'll have to see how much snow and wind this next wave brings.</p> <p>I spot probed a number of locations in upper Cardiff today and found consistent snow depths of 200 to 230cm, and I think the odds of a deep slab in these areas with deeper snowpack are very low to none. Slopes with shallower snowpack (that have avalanched this season or on the periphery of the Cottonwoods) still have questionable structure and are still adjusting to a significant new load.</p>
A fair amount of complexity in the aftermath of such a warm storm. It seems like the top of the current snowpack can be categorized fairly well in three different elevation zones. Below 9,000': It seems like terrain below 9k saw mostly or entirely rain. There was a pretty stout refreeze crust (supportable for skis and boots) at this elevation above Alta Central this morning, with wet snow underneath. I think that this elevation will become very stable once it has a chance to thoroughly drain and freeze. 9 to 10,000': Things are a bit funky in this elevation range. There were a few inches of graupel on the snow surface, on top of a rain crust (generally supportable for both skis and boots), on top of another few inches of graupel, on top of the old snow. The graupel on the surface got quite warm, and seemed to be consolidating/bonding to itself. The graupel below the rain crust was fist hardness and very poorly bonded, still very "ball bearing"esque. I don't think this is a concern for now, but I will be interested to see if this layer becomes reactive the first time that it warms and becomes saturated. Above 10,000': It seems that nearly all precip above 10k fell as graupel. Wind loaded snow on top of this graupel layer was touchy, the graupel here was also poorly bonded and acting as a weak layer.