AVALANCHE ADVISORY PUBLISHED ON JANUARY 28, 2021 @ 6:48THIS ADVISORY IS VALID FOR 24 HOURS
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center
EXTREME AVALANCHE DANGER exists today as a powerful winter storm impacts the Eastern Sierra. Heavy accumulations of new snow and loading southerly winds will build Slabs on All Aspects. Avoid all Avalanche terrain as natural and human triggered avalanches are certain.
6. Extreme [danger]
Above Treeline
6. Extreme
Near Treeline
6. Extreme
Below Treeline
AVALANCHE PROBLEM #1: WIND SLAB
ASPECT/ELEVATION [The Center provides an image of all aspects and elevations, and the risk was high on pretty much all aspects except South-South-west]
LIKELIHOOD-- Certain
SIZE-- Historic, Large
Strong to moderate southerly winds optimal for loading combined with massive amounts of new snowfall (4-6ft+) will be building reactive and deep wind slabs on virtually all aspects and elevations. W-N-E-SE will be aspects of primary concern with guaranteed wind slab development adjacent to ridgeline and terrain features conducive to capturing wind transported snow such as cliff bands, convex rollovers and gullies. Avalanches of all sizes and scope are nearly certain today. Large to very large avalanches have the potential to run into lower terrain where you may normally think you are safe. Avoid all avalanche terrain!
AVALANCHE PROBLEM #2: STORM SLAB
ASPECT/ELEVATION -- [All aspects]
LIKELIHOOD-- Certain
SIZE-- Historic, Large
Incredible amounts of new snow (4-6ft and likely more in some areas) fell Wednesday; snowfall was unrelenting through last night and will continue today. Fresh, sensitive, and unstable storm slabs on All Aspects at All Elevations are guaranteed to be present. In the midst of a storm of this magnitude avalanche conditions will be extremely dangerous as new snow will be looking to adjust its balance in relation to gravity and slope. This means avalanches in all forms, from soft sensitive slabs on virtually any slope with a bit of steepness, to loose dry point releases in very steep terrain.
AVALANCHE PROBLEM #3: PERSISTENT SLAB
ASPECT/ELEVATION -- [Northwest to Southeast]
LIKELIHOOD-- Certain (Now downgraded to "Very Likely.")
SIZE-- Historic , Large
This hefty storm is rapidly loading the shallow and loose-grained snowpack from November and December with a significant amount of weight. W-SE aspects all harbor weak structure from our prolonged drought through the first half of the winter. The rapid loading and large amount of weight in the new snow will likely cause collapse and failure in these old weaker layers. Avalanches originating from fresh unstable wind/storm slab and loose dry will add to the pressure on these weak persistent layers and could cause avalanches to “step down” into the older snowpack causing much bigger and destructive avalanches.