Eastern Sierra avalanche advisory
Posted May 15, 2010 by Sue Burak
This is the final snowpack and avalanche statement for the 2009-2010 season. Thanks for your interest- see you in November or December!
Sue Burak and Josh Feinberg
Expect significant variability in conditions through the region and from one day to the next. Reports of variable conditions ranging from funky snow off the Dana Plateau to winter snow in the Powerhouse Chutes and in sheltered gullies from Rock Creek, the Palisades and the southern Sierra provide the general picture of snow conditions to expect on north facing aspects. Spring snow conditions are found from mid to high elevations on east, south and west aspects. There are no reports of skier or rider triggered avalanches in the chutes but plenty of human triggered wet slide activity on steep sun exposed slopes.
Some techniques to manage hazard: Start early and finish early. Pay attention to night time low temperatures- if lows are above 32F, the snow did not get a solid refreezing and unstable conditions will begin early in the day rather than mid day or early afternoon.
Cut the tops of slopes before riding them. Pull over periodically to let any loose-snow avalanches run by. Pay attention to clues like current pinwheeling, slushy surface snow, or new loading by snow and wind, which suggest a greater likelihood of avalanches in specific terrain features. Keep in mind that even small avalanches can have dire consequences if terrain traps are in the runout.
Terrain to avoid- Stay well back from the edge of ridges until you are certain about any cornices. Avoid overhead exposure from steep rocky slopes and cornices, especially after prolonged sun-exposure.
Unsettled weather is expected to continue until the end of May. The pattern of a weekly spring storm accompanied by cooler temperatures and gusty west to southwest winds continues for at least a couple of weeks. Temperatures will see saw from highs at the 8,000 to 9,000 ft elevations around 60 F during the clear part of the week dropping to the mid to upper 40’s during the weekly storm period. The high elevations above 10,000 ft are expected to see seasonal temperatures for the extended with highs in the upper 40’s to mid 50’s and cooling to the upper 30’s during the unsettled periods.
The warming trend continues into the weekend with temperatures above normal. 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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