Eastern Sierra - Fri Mar 26 2010
Eastern Sierra avalanche advisory |
The avalanche danger will be generally LOW through the day today.For Saturday, the avalanche danger is estimated to remain LOW and keep an eye out for wet avalanches on east to southerly aspects from 8,000 to 11,000 ft. Steer clear of steep gullies and terrain traps where wet activity can pile up debris several feet deep. |
Cold west to northwest winds over the last two days continue to create windboard, breakable crusts and generally unpleasant ski conditions in the higher terrain. The main concern today is taking a slider on frozen melt freeze crusts in steep terrain.
By Saturday, wet snow avalanche activity will be the main avalanche concern. Traditional snowpit tests don’t work in wet snow and it is up to you to watch how quickly temperatures warm up.
Right now, night time temperatures have been in the low to mid 20’s and corn snow production conditions were favorable before the last cold snap.
Sunny corn snow slopes, once they begin to heat up and the surface snow melts, can quickly go from being solid and supportive to a deep wallow and risky wet loose snow avalanche conditions. Allow extra time to get somewhere, have a great day and get off the snow before conditions get too warm for safety.
Keep in mind wet slab avalanches are possible at some mid and lower elevations where the snowpack is shallow and damp to the ground. While I have not observed any wet slab avalanches this year, they are possible given the January 13 layer that a couple of us can still find about 20-30 cm above the bottom of the pack north of the Mammoth Lakes area.
This is the time of year that cornices become unstable and sensitive to release by the effects of sun and warming. Extra caution is advised on slopes below cornices and on ridgelines close to cornices.
One more cold day before the weekend warmup brings us back to spring. The weather is going to change back to winter by Monday or Tuesday so enjoy the weekend sun and mild temperatures.
For today cool and windy weather continues to keep temperatures in the mid 20’s over the higher alpine terrain. Strong wind gusts over 60 mph continue through the day and elevations above 10,000 ft will have wind chills in the -10 to -20F range.
Mid elevations from 8,000 to 9500 ft will see highs in the upper 30’s today with gusty northerly winds.
A short lived high pressure ridge builds over our area tonight and warmer, milder weather will return over the weekend. Starting on Monday of next week, a return to cold and wet wintry weather could produce significant amounts of snow through Wednesday.
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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