Eastern Sierra Avalanche Forecast - 1/3/14

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THIS AVALANCHE ADVISORY EXPIRED ON January 4, 2014 @ 7:12 am
Avalanche Advisory published on January 3, 2014 @ 7:12 am
Issued by Sue Burak - Inyo National Forest
bottom line

There is not enough snow cover to issue avalanche advisories. A snowpack discussion is available as a text discussion.

How to read the advisory

Bottom Line

There is not enough snow cover to issue avalanche advisories. A snowpack discussion is available as a text discussion.

advisory discussion

The current snowpack is faceted top to bottom - if you can even call it a snowpack. In some places there are thin to thick suncrusts, other places the snow surface is recrystallized particles. Despite the thin coverage, as long as the ground has an insulating blanket of snow, the ground is almost always warm--near freezing--even with very cold air temperatures. Depth hoar forms from large temperature gradients between the warm ground and the cold snow surface. Since the snow cover is about 12 inches in most places, there is a huge change in the snow temperature from the ground (32F) to the snow surface, which in the morning ranges from 14 to 26 F.  

 

The thin snow cover is subject to high temperature gradients and without snow on top, the depth hoar will not strengthen as it does when there is snow sitting on top of depth hoar. There are several suncrusts sandwiched between faceted layers. Each suncrust represents the period of time between storms. The facets are the storm snow that changed into weak facets under strong temperature gradients combined with shallow snow and cold temperatures. Forecasters never underestimate the persistence of faceted snow as a weak layer and depth hoar avalanches can be large and scary. It commonly propagates long distances, around corners and easily triggered from the bottom--your basic nightmare.  Walter Rosenthal took this picture of a large depth hoar avalanche along the Cliffs on Mammoth Mountain.

weather

Quiet and dry weather is expected through Monday. Temperatures will be mild today with highs at the 8,000 to 10,000 ft elevations in the 46 to 52 F range. Higher elevations will see highs in the low 40’s. Nights continue to be mild with lows in the 20’s.

Latest projections show the potential for one or two relatively weak storms to impact the region in the Tuesday-Thursday time frame next week.  These will not be big storms and any precipitation will be on the light side.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
  Friday Friday Night Saturday
Weather: clear clear clear
Temperatures: 42-48 deg. F. 20-25 deg. F. 45-50 deg. F.
Wind direction: n n n
Wind speed: calm calm light
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
  Friday Friday Night Saturday
Weather: clear clear clear
Temperatures: 39-45 deg. F. 20-25 deg. F. 38-41 deg. F.
Wind direction: N N N
Wind speed: calm light light
Expected snowfall: 0 in. 0 in. 0 in.
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