Avalanche Advisory for 2014-12-26 07:06:10

Greetings and Happy Holidays to all! The Mt Shasta snowpack took a big hit due to warming temperatures beginning late last weekend. Saturday night and into Sunday, the area saw temperatures rise rapidly creating a massive tree drip and consolidation of the snowpack. Over Christmas week, we experienced several more warm days leading to further consolidation. Since last Sunday the 21st, the Old Ski Bowl weather station reported 10 inches of settlement. Runnels from warm temps began to take form all the way up to about 9,000 feet over the week. 

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

Northwest flow has been dominating and providing windy conditions on the mountain for most of the week. 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, however it's by no means good skiing. Areas of deeper wind blown powder can be immediatly followed by bullet proof ice/snow as one slides down the hill. 

Wind loading of leeward slopes and the formation of wind slabs has and will be the current avalanche problem. 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, northwest 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.