Unseasonably cold temperatures have settled into the region with light to moderate Southwesterly winds as another Pacific Northwest storm begins to take aim at northern California on Wednesday. The most recent storm (1/19 -1/20) yielded 4” to 7” of snow in the Mammoth region, 6” to 8” June Lake and north with little wind effect, leaving a very uniform blanket of light transportable snow. Since then, Monday saw steady southwesterly – westerly/15 to 25 mph as a weak disturbance passes to the north of the forecast region, forming fresh Wind Slabs on NW-N-NE-E-SE-S aspects. Southwesterly winds are forecasted to decrease to 10 to 15 through the day (Tuesday) but pick back up by evening ahead of an approaching storm system due to move into the region Wednesday. Light to moderate winds will continue build wind slabs near and above treeline until downwind fetches are exhausted. Watch for signs of blowing snow and wind loading (snow banners, recent cornice formation, and fresh drifts). Caution is recommended in steep alpine terrain.
Treeline and below - due to the recent cold temperatures the persistent weak layer that has plagued us through much of the early part of the season is showing signs of further weakening in the Mammoth area, renewing concerns for potential deep releases, if this trend continues. A recent report of whumphing in the Mammoth Lakes Basin and tests indicating propensity for propagation highlights this problem layer and the potential for failure. Whumphs (sudden collapse) are a strong sign of instability. Do your own stability assessments, especially as you enter steeper or complex terrain.
Below ~9,000’ the new snow will not be enough to cover the rocks and brush poking up from the surface.