Eastern Sierra - Wed Jan 6 2010

In very isolated areas in extreme terrain, small avalanches are possible. The avalanche danger is estimated to be LOW on slopes where there is enough snow for an avalanche to occur. Continue to use caution and evaluate any steep slope where a stronger slab of snow exists over weak, sugary snow especially around rocks.

 

Throughout the region, the snowpack can be characterized as shallow and well bonded. Daytime highs in the 40's and lows in the mid 20's have helped to reduce temperature gradients and promote the strength of the snowpack. If cold weather moves into the area, things will get interesting as temperature gradients will increase and drive changes in snow structure, but until then, it is business as usual in the Sierra snowpack.

Up on the surface of the snow, recrystallization continues on colder, shaded slopes. This means the snow surface is weak and could form a weak layer once there is new snow. Surface hoar can be found in open areas where the cold night time air pools in low lying areas and around open water. These layers could also become a tricky problem when snowfall occurs again.

Weak energy moving through the top of the high pressure ridge produced light precipitation in far northern California. The eastern Pacific is covered with high moisture clouds but despite El Nino predictions of a dry Pacific Northwest, Oregon has 180%of normal snowpack for this time of year.

For today, cloudy skies are just the sign of the snowfall occurring to the north. Some light precipitation is expected to spread down the Sierra later today and tonight but expect only a trace to one or two inches in the northern part of Mono County.

Warmer than usual temperatures continue for the next week. Highs today at the 8,000 to 10,000 ft will be in the mid 40's and light north winds. Some locations will not reaching freezing temperatures tonight. Higher elevations will be only slightly cooler with highs in the 40's and lows in the mid 20's.

Look for a pattern change by the third week of January. For details on the potentially wet MJO/El Nino event, contact me at sb@snowhydrology.com or 924.5510 and leave a message with your contact information.

Threat #3

Stable weather, stable avalanche conditions. In many places in Bishop Creek and Rock Creek there is not enough snow to avalanche. In the Mammoth and June areas, there is adequate snowcover above 8,000 ft and a Low avalanche danger rating. .

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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.

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