Heavy snowfall continued across the Southern Mountains Monday delivering abundant cold smoke powder to all mountain locations. 6 to 14 inches accumulated in the North San Juan zone while the South San Juan zone got pummeled with 10 to 24 inches favoring the La Plata Mountains and Wolf Creek Pass. Let’s not forget about the Sangre de Cristo Range who got in on the action with up to 10 inches reported at higher elevations. Storm totals range from one up to three feet of snow since Sunday night.
Our current storm is not adding the same load and shock to the snowpack as the previous storms in February. However, snow water totals range from one to almost two inches of SWE and this is enough of a load to stress buried weak layers that formed during dry weather in late January. As snowfall continues today storm slabs will thicken, become more widespread and may be more reactive than what observations hinted at on Monday (ob 1, ob 2). Small changes in wind direction or breaks in recent storms formed different layers in the upper snowpack. Monitor the impact new snow is having on these interfaces before committing to a slope. Digging into the snow is the best and easiest way to accomplish this and evaluate the ease of triggering an avalanche in recent storm snow.
We are less than a week out from our last natural cycle that produced dangerous avalanches breaking near the ground or on mid-to-upper snowpack layers such as near-surface facets and faceted crust. These avalanches were two to three feet deep, large, and dangerous. CAIC forecasters traveled near Ophir on Sunday and observed clean and fast shears at the interface between the old snowpack and bottom of February snow. Anticipate that an avalanche triggered near the surface could step down to deeper weak layers making a larger and potentially more deadly avalanche.
We also can’t ignore facets and depth hoar near the ground. On a lot of slopes throughout the San Juan’s, these scary layers are now buried under a two meter thick slab. Many slopes that avalanched in mid-January harbor weak facets sitting above a firm old bed surface below a cohesive slab. These areas are primed and ready to avalanche if they didn’t during last week’s cycle. Some of these slopes might only be waiting for a trigger to fail. Larger storm slab avalanches or avalanches failing on faceted snow below February snow could step all the way down to the ground and create an un-survivable avalanche.
The general trend of the snowpack is good on a seasonal scale as we are building a deeper and stronger snowpack. For today, dangerous conditions exist and the snowpack needs time to adjust to the new load and find equilibrium from abundant snowfall this month. Continue to be diligent in your snowpack evaluations and consider the consequences of triggering a larger avalanche before committing to steeper terrain.