Avalanche Advisory for 2014-12-27 06:57:36

Wind loading of leeward slopes and the formation of wind slabs is the current avalanche problem. That said, observations in the last 3 days have found these wind slabs to be stubborn to trigger. Observed slabs near and above treeline in the Old Ski Bowl and Gray Butte areas have been small, and about 10-35cm deep on top of the old snow. Skiers and snowmobilers recreating all over the mountain out of the Bunny Flat trailhead have reported no instability within slab layers. However... yesterday, stability tests within a 34cm wind slab on a south facing, low angle slope resulted in moderate failures (ECTN11/ECTN15 - Q2) about half way down the slab. Small facet growth (+/- 1mm) was observed at this weak layer, but numerous extended column tests could not produce full propagation. Based on this test and ski and snowmobile cuts on small convexities, full slope propagation within this weak layer seems unlikely. To sum this all up, medium to hard wind slabs on all aspects near and above treeline are isolated, small (6-12inches deep), and stubborn to trigger.

The Mt Shasta snowpack took a big hit due to warm temperatures over Christmas week. In the last 6 days, we've seen upwards of 12 inches of settlement. Runnels in the snow as seen in photo below, not from rain, but simply from warm temps, have taken form all the way up to about 9,000 feet on the mountain. These formations are now rock solid and with cold temperatures becoming colder, they are likely here to stay until we receive more snow!

Climbers and skiers venturing onto steeper slopes of Mt Shasta: the smooth, firm and icy conditions we are seeing currently have produced severe injury/fatality to climbers and skiers from slide for life, slips and falls. Self arrest and ice axe and crampon skills are mandatory to travel safely in said conditions. Be prepared and know how to use your equipment.

Runnels from warming over the past week. {Photo: C. Carr}

Periods of strong northerly winds for most of the week have created firm, hard and slick condtions near and above treeline. We've seen gusts to 92 mph and average wind speeds of 40-60 mph at times. Below treeline, the 4-6 inches of new snow that fell near Christmas Day has blown in fairly evenly in the trees, and a few folks have reported some decent skiing in protected areas. Overall though, the firm, hard old snow is still being found with ski edges and a nice swath of shallow powder and/or wind packed powder can be immediately followed by teeth chattering ice. 

The Old Ski Bowl near the Wilderness Boundary, 12.26.14

Last weekend, sometime late Saturday or Sunday (visibility very poor until Monday), a large and impressive slide occured in the Old Ski Bowl (HS-N-R3-D3). The crown of this slide was approximately 1/4 mile wide and 1-3 feet deep. The starting zone was from 10 to 10,500 feet and the toe of the debris ended at 8,300 feet. This slide is another good reminder to remain aware of the terrain AND potential for avalanche danger ABOVE you. Conditions and avalanche danger can vary greatly as elevation changes. While one might experience low avalanche danger below and near treeline, the danger can be much higher on the upper mountain.

Above treeline yesterday, north/northeast winds were visually obvious off Casaval and Sargents Ridgelines. Keep in mind however, due to local orographics, winds can blow in different directions than the primary flow aloft. This can and will create wind loading on slopes not immediately thought of. Snow conditions overall are bullet proof and icy with mixed pockets and pillows of wind blown powder. One will find the best skiing in low angle, wind loaded gullies and depressions... or we will have to wait for a melt/freeze cycle! 

Old Ski Bowl Slide... the entire crown line wouldn't fit in the camera frame! Lookers left and right crown lines, five days later.

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 still has very little snow and no skiing is being had yet.

Mt Eddy area is hosting about 2-3 feet of snow in Wagon Bowl. I have not been up into that area yet and have received no reports.

Sand Flat Winter Trails: OPEN and in good shape!

Pilgrim Creek Snowmobile Park: OPEN, however due to lack of low elevation snow, one must drive up the road a few miles before enough snow is encountered.

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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.