Eastern Sierra - Sat Jan 23 2010
Eastern Sierra avalanche advisory
Posted January 23, 2010 by Sue Burak
The avalanche danger rating is High today on north to east facing terrain that continues to be windloaded by strong west to southwest winds.
As skies clear and powder fever ramps up in intensity, let’s ski to live for another day rather than ski to die. The mountains are asking for a fair amount of respect over the next couple of days. Consider this before you go- there was a relatively calm period with little wind yesterday morning. During the calm period, a couple of inches of snow fell in the Mammoth area with more falling on June Mountain. Southwest winds picked up after the lull in the storm, temperatures increased a few degrees and snowfall rates of over 1 inches per hour created another windslab over the lower density snow. This is the perfect setup for wind slabs to develop and has been repeated many times over the last five days. June Mountain ski patrol reported cracking and shooting cracks yesterday. Whumpfing and propagating cracks are certain signs the snowpack is unstable.
There is another avalanche concern, particularly at the 7,300 to 9,000 ft elevations in the June Lake area. Ski patrol has triggered avalanches releasing on a rain layer formed on January 9. Weak faceted snow has been observed on top of the rain layer. One observer reported increasing instability in 24 hours from snowpit stability tests as new snow load was added. Don’t be fooled into thinking the steep tree skiing around June Mountain is safe just because you are in the trees. If you trigger a slide on the rain layer, the avalanche will likely be large. Today is a good day to hit the ski areas.
As the strong storm moves east to hit Utah and the Ruby Mountains, the sun might appear briefly today between snow showers. By the weekend, skies will be mostly sunny and temperatures will warm up from the 20’s to 30-35F at 8,000 ft. Expect snow showers today and southwest winds decreasing to 10-20 mph. Temperatures will be in the upper 20’s.
For today, elevations above 9,000 ft will continue to have snow showers with possible accumulations of around 6 inches. Southwest winds will decrease to 15 to 20 mph with gust to 50 mph. By the afternoon, ridgetop wind gusts will decrease to 30 mph- almost balmy for our region.
By Sunday night, a storm reaches the West Coast and splits. The eastern Sierra will pick up some new snow but the main energy is focused north and south of our area.
A widespread natural avalanche cycle occurred after the storm. Large avalanches occurred on McGee Mountain, the Mt. Morrison area, Sherwin Ridge and Naturally occurring avalanches reported in the June Mountain area. Slab avalanche debris on McGee Mountain. Expect to see widespread avalanche cycle after skies clear.
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.
ESAC is operating on a limited budget and is supported by its members and the community. Please help support the Center by becoming a member today. Visit the Support area for more information.