Eastern Sierra - Wed May 12 2010
Eastern Sierra avalanche advisory |
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We are heading into a nice week. Warm temperatures and strong sun will consolidate the storm snow today. The biggest thing to watch for is the sluffing of storm snow once it gets wet. In the Rock Creek and Bishop Creek areas, only a few inches of snow fell and wet slides in the new snow could remain small. Yesterday, there was a sun crust in addition to dense new snow on north to southern aspects in the Rock Creek area. |
After the snowpack stabilized last week by several daily cycles of increasing loose and wet loose slide activity, the cycle has to start all over again. The cold temperatures, strong winds and some new snow set us back to winter. While north and east winds today should help limit the effects of warming on wind exposed terrain, there will likely be wet snow avalanche activity, mainly smaller loose and wet loose slides.
We are heading into a nice week. Warm temperatures and strong sun will consolidate the storm snow today. The biggest thing to watch for is the sluffing of storm snow once it gets wet. In the Rock Creek and Bishop Creek areas, only a few inches of snow fell and wet slides in the new snow could remain small. Yesterday, there was a sun crust in addition to dense new snow on north to southern aspects in the Rock Creek area.
In areas with 6-9” of new snow, you want to be off steep slopes before the new snow loses strength-when that transition happens will be elevation and slope-dependent, but will generally follow the sun from east to west. In the Mammoth and Tioga Pass area, once the sun melts the snow surface there could be small point release avalanches that could entrain increasing amounts of moist or new surface snow and slides descend, particularly in steep lines on wind sheltered slopes.
The daytime warming or sunshine should also result in some cornice collapses which may trigger slides on the slopes below. As a result, back country travelers should use increasing caution when traversing through sun exposed terrain, areas receiving heavier showers, or slopes showing evidence of recent wind transport.
The cold, wet, windy storm is giving way to sun and a gradual warming trend. New snowfall amounts range from 2 inches in the southern Sierra to 8-9” in the Mammoth area north to Tioga Pass. The new snow has drifted and loaded and there is a potential for small slab avalanches today, especially this morning.
Mostly sunny skies and warmer temperatures are expected today with a few snow showers developing over the crest late tonight and Thursday morning. The warming trend continues into the weekend with about 5 degrees of warming each day. However, another storm is forecasted to bring temperatures back down to the 30’s by Monday and Tuesday of next week.
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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