Eastern Sierra Avalanche Forecast - 2/8/14

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THIS AVALANCHE ADVISORY EXPIRED ON February 9, 2014 @ 8:14 am
Avalanche Advisory published on February 8, 2014 @ 8:14 am
Issued by Sue Burak - Inyo National Forest
bottom line

The avalanche danger this morning is MODERATE near treeline and above treeline on all north facing slopes above 9,000 ft 35 degrees and steeper.  Wind slab, storm slab and deep persistent slab avalanches are all possible today.

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Bottom Line

The avalanche danger this morning is MODERATE near treeline and above treeline on all north facing slopes above 9,000 ft 35 degrees and steeper.  Wind slab, storm slab and deep persistent slab avalanches are all possible today.

  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small
  • Trend ?
    Increasing Danger

Strong southwest and west winds formed small areas of wind drifts below ridgetops and in steep gullies and open slopes below the Mammoth Crest yesterday. Wids continued to blow overnight and snow is falling this morning as the next storm reaches the area. New snow and continued winds will increase the avalanche danger during the day.

Avalanche Problem 2: Persistent Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Trend ?
    Same

Buried weak snow is becoming less reactive in tests.  Additional loading today and tomorrow will test this layer. The weak snow structure is a red flag and should be considered in your slope evaluation.

recent observations

Strong winds created pockets of unstable snow yesterday on high elevation slopes near the Mammoth Crest. An observer reported a small natural slab avalanche in the Duck Pass area. Small wind drifts in wind exposed areas above Cyrstal Lake were very sensitive to the weight of a skier and small wind slab avalanches ran 50 to 100 ft.

CURRENT CONDITIONS Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 29 deg. F.
Max. temperature in the last 24 hours: 27 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 60 mph
Maximum wind gust in the last 24 hours: 104 mph
New snowfall in the last 24 hours: 7 inches
Total snow depth: 28 inches
weather

The first wave of moisture associated with a winter storm passed through the area last, leaving a disappointing 6-8" of new snow above 9,000 ft in the Mammoth Lakes area. A stronger storm with higher snow levels will drop south from the Lake Tahoe area- NWS forecasters told me to expect another foot of snow today and night with another foot or more of snow tomorrow above 9,000 ft.

Daytime highs will be in the upper 30's above 8,000 ft.  Higher elevations will be mild with daytime highs reaching the mid 30's. Snow accumulations today of 12" or more are expected above 8,500 ft. Strong winds will continue through most of the day.

 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
  Saturday Saturday Night Sunday
Weather: snow snow snow
Temperatures: 26-34 deg. F. 24-32 deg. F. 26-34 deg. F.
Wind direction: SW SW SW
Wind speed: 30-40 30-40 20-30
Expected snowfall: 6-8 in. 10 in. 12 in.
Over 10,000 ft.
  Saturday Saturday Night Sunday
Weather: snow snow snow
Temperatures: 20-26 deg. F. 18-24 deg. F. 20-26 deg. F.
Wind direction: SW W W
Wind speed: 55-65 45-55 35-45
Expected snowfall: 12 in. 12 in. 12 in.
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