Avalanche Advisory for 2015-01-16 07:05:25

Conditions over the week did not change much and while a few were able to find some warmer patches of corn snow during some warm spells, overall conditions remained firm and variable. On the upper mountain, while fairly smooth, the snow most definitely did not soften for folks venturing up there. Slide for life snow conditions still exist for the steeper slopes above treeline on Mt Shasta and climbers and skiers should be prepared for said conditions. A helmet, ice axe and crampons are recommended...and know how to use them (ie. self-arrest!)

Of most interest is the incoming/in process storm(s) for the area. We've got a firm and smooth bed surface for most of the forecast area right now. New snow totals over the weekend could accumulate to 6-8 inches near and above treeline. Westerly winds will give us a strong breeze to moderate gale at times. New snow and wind points to wind slab formation on leeward aspects....some uncertainty exists for how deep wind slabs will be and their sensitivity to trigger. This storm is on the warmer side, so I would expect new snow bonding to be good at lower and mid elevations. As one moves into mid and upper elevations (>9,000 feet), conditions will be different and the chance of triggering wind slabs greater. Precipitation and wind will occur all weekend and careful terrain selection will be important as wind slabs build.

Storm slabs are not a concern at this moment, though depending on how much new snow we get this weekend, storm slabs could become an avalanche problem. This type of avalanche involves the release of a soft, cohesive layer (slab) of new snow which breaks within the storm snow or on the old snow surface. Storm slabs are more prevalent at the higher elevations on all aspects. They tend to settle out and stabilize within a few days unless deposited on a persistent weak layer.

Report your observations to the MSAC! A photo, a few words... send them in! (nimeyers@fs.fed.us or 530-926-9614)

Castle Lake area has a shallow snowpack. Be careful of shallow buried objects. Skiing has been reported as poor to non-existent.

Sand Flat Winter Trails: OPEN

Pilgrim Creek Snowmobile Park: OPEN, however due to lack of low elevation snow, one must drive up the road several miles before enough snow is encountered. One CANNOT DRIVE over Military Pass.

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Terrain:  Remember most of the terrain that we like to play on is greater than 30 degrees.  Avalanches are possible on anything steeper than 30 degrees.  Avoid cornices, rock bands, terrain traps and runout zones of avalanche paths.

Weather:  Most of our areas avalanche danger will occur 24-48 hours after a storm. We still can see persistent weak layers from time to time and we always will be sure to let you know about that!  Heed the basic signs: Wind (significant snow transport and depositions), Temperature (rain/snow/rain/snow, which in turn weakens the snowpack), and Precipitation (Snow or rain add weight and stress to the current snowpack).

Snowpack:  If snow accumulates, give the snowpack a chance to adjust to the new snow load before you play on or near steep slopes (greater than 30 degrees).  Most direct action avalanches occur within 24-48 hours of recent snowfall.  Watch for obvious signs of snowpack instability such as recent natural avalanche activity, collapsing of the snowpack (often associated with a “whumphing” sound), and shooting cracks. If you see these signs of instability, limit your recreation to lower angle slopes.

Human Factor: Don’t forget to carry and know how to use avalanche rescue gear. You should NOT be skiing or climbing potential avalanche slopes without having beacons, shovels, and probes.  Only one person in a group should be exposed to potential avalanche danger at a time.  Remember, climbing, skiing, and riding down the edge of slopes is safer than being in the center.  Just because another person is on a slope doesn’t mean that it is safe.  Be an individual!  Make your own decisions.  Heed the signs of instability: rapid warming, “whumphing” noises, shooting cracks, snowing an inch an hour or more, rain, roller balls, wind loading, recent avalanche activity.

The Five Red Flags of Avalanche Danger any time of year include:  1) Recent/current avalanche activity  2) Whumpfing sounds or shooting cracks  3) Recent/current heavy snowfall  4) Strong winds transporting snow  5) Rapid warming or rain on snow.