The avalanche danger rating is estimated to be LOW today. Watch for thin wind slabs on isolated northwest and north facing slopes at mid to higher elevations in the Mammoth Lakes Basin. Moderate east and north winds yesterday created isolated areas of thin wind slabs on northwest and west facing high elevation terrain. When the avalanche danger rating is LOW, small avalanches can occur in isolated areas or in extreme terrain.

 

Cold east and north winds created some snow plumes yesterday in the Mammoth Lakes Basin. Isolated and small areas of thin wind slabs formed below mid and high elevation ridgetops and in wind exposed areas in north and northwest facing terrain. Watch for isolated areas of unstable snow on these slopes. Small avalanches can occur in isolated areas or extreme terrain when the avalanche danger rating is LOW.

The return to seasonal temperatures felt cold the last two days compared to the warm, mild 40F to 50F temperatures of last week. Seasonal mid winter temperatures in the upper 20’s and 30’s will continue for the rest of the week and provide favorable conditions for faceting to start transforming the shallow snowpack. Today, the snow temperature profile had a 10C difference in 65cm- a very favorable temperature gradient promoting faceting at the surface and within the snowpack. Mid day surface hoar had formed and rounded grains were gaining edges. Large well developed depth hoar with striations, cups and prisms were visible with the naked eye.

Surface hoar, mid pack facets and depth hoar are not an avalanche problem until they are buried by new snow. If air temperatures warm to above average, the faceting process will slow down and facets can return to more rounded forms. At this point in an unusually dry winter, new snowfall is welcome no matter what the snow surface conditions are at the time.

Light to breezy north to northeast winds continue for the next few days, gusting to 30 mph along the ridgetops. Temperatures will be close to normal for this time of year with highs in the mid 20’s for higher elevations and mid 30’s for the 8,000 to 9,500 ft elevations. Mornings will be cold with mild, mid winter afternoons.

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Please note that the avalanche danger rating in this advisory expires in 24 hours. This advisory is our best interpretation of snow pack conditions and NWS forecasts issued today. Backcountry travelers should be aware that elevation and geographic distinctions are approximate and that a transition zone exists between upper and lower elevations. Avalanches do not happen by accident and most human involvement is a matter of choice not chance. Most avalanche accidents are caused by slab avalanches that are triggered by the victim of member of the victim's party. Even small slides can be dangerous. Always practice route finding skills and carry avalanche rescue gear. Remember that avalanche danger ratings are only general guidelines. Distinctions between geographic areas, elevations, slope aspects and slope angles should be made.