A brief snowpack update from 11/18/17
The Eastern Sierra Avalanche Center will begin issuing regular Avalanche Advisories beginning December 1st. Until then, here is a brief summary of conditions following the Eastern Sierra’s first significant Atmospheric River and real winter storm of the season.
The hose really turned on over the Eastern Sierra from Wednesday morning thru Friday morning (11/15-17). This warm system brought heavy rains below 8000’, but above 8500’, and especially above 9000’, temperatures were cold enough that much of this moisture fell as heavy dense Sierra Cement snow. Perfect really for this time of year, caking in the higher elevations and filling in the cracks. Snow sensors around the 10,000’ level across the forecast area were reading 1-2ft of new snow, mostly on top of what was previously bare ground. Mammoth Mountain reported areas with 4+ feet of new snow near the summit, especially where the very strong winds deposited the snow into deep wind slabs. Yesterday morning (11/17) there were widespread avalanches across the top of Mammoth Mountain as a result of avalanche control work with crowns that reached the ground. The greatest avalanche concern that exists right now (11/18) is wind-slabs that could remain sensitive to human triggering from the high winds that howled throughout this storm at all elevations. As time passes these wind slabs will stabilize, until more snow falls and winds pick up again. Avalanche concern this weekend could also exist in the form of wet slides, as slopes with fresh snow warm from sunny skies, high temperatures reaching near 50 degrees at the 10,000’ level, and calm winds.
And remember, just because the skis and boards don’t sink in very deep in this dense snow doesn’t mean there aren’t PLENTY of early season obstacles that are both visible and hiding just below the surface. Be careful out there, and don’t end your season before it even begins!
- Josh Feinberg