Surface conditions before last nights storm consisted of the full gamut of wind shorn, eroded wind slab to shiny slick rain/temperatures crusts and some residual recycled powder in sheltered areas. Relatively cold temperatures coinciding with this storm will make it interesting to see how well the new snow bonds to all those residing surfaces. Up to 10” of snow fell in the Mammoth area and averaged around 5” across other parts of the zone from north to south. Nearly 1” SWE (Snow Water Equivalent) was recorded in the Mammoth snowfall totals which is a decent amount of new weight being added to the snowpack. We need to be cognizant of how, or if, this new added weight potentially affects some of the weaker snow associated with the Dec 12 rain crust that currently exists in the snowpack. Northerly-Easterly aspects around 9300-10500ft is where this rain crust is buried, averaging around a foot below the surface and in some wind-loaded places much deeper. This rain crust and associated weaker faceted snow either above or beneath it has been showing a propensity for propagation on snow stability tests. This new added weight of snow and a skier trigger could be the right recipe for the snow to "step-down" to these rain crusts and start a slab avalanche.
Be observant today for signs of instability such as recent avalanches, or areas of snow sensitive to skier trigger. If you’re seeing shooting cracks or loose snow moving on your way up, it’s sure to be more active on your way down. Wind slab will be the biggest hazard so be on the lookout for clues such blowing snow, recent cornice growth, and fat, pillowed snow surfaces. Cold temps are not only good for riding conditions, but are also conducive of Loose-Dry Snow Avalanche potential that will be of particular concern if you’re getting into extreme or complex terrain.
Early Season Obstacles Exist! If you’re visiting the area for the first time this season, take note that although there is a decent snowpack in the Mammoth area and high elevations of the forecast zone, a majority of the area still has early-season coverage.