Eastern Sierra Avalanche Forecast - 3/31/14

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THIS AVALANCHE ADVISORY EXPIRED ON April 1, 2014 @ 7:05 am
Avalanche Advisory published on March 31, 2014 @ 7:05 am
Issued by Sue Burak - Inyo National Forest
bottom line

The avalanche danger is MODERATE in steep, wind-loaded upper elevation terrain. Expect variably sensitive, new 8-12" deep wind slabs near ridgelines on north facing  aspects. The avalanche danger rating is LOW on slopes in tree covered terrain.  Expect the avalanche danger rating to increase tomorrow as another 12-15 inches of new snow is expected to accumulate from tomorrow night through Tuesday. 

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 is MODERATE in steep, wind-loaded upper elevation terrain. Expect variably sensitive, new 8-12" deep wind slabs near ridgelines on north facing  aspects. The avalanche danger rating is LOW on slopes in tree covered terrain.  Expect the avalanche danger rating to increase tomorrow as another 12-15 inches of new snow is expected to accumulate from tomorrow night through Tuesday. 

  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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The peak of instability yesterday occurred during the early to mid morning hours. Windslabs will be more stubborn to triggering today, though it is possible to trigger a wind slab in steep north facing terrain in alpine areas.  Expect instability to increase this evening when the next storm reaches the area and drops another 12" or more of snow along with moderate southwest winds in the 40-50 mph range. This time of the year, you should expect conditions to change with subtle differences in aspect and elevation - don't assume different slopes are going to behave similarly. 

Avalanche Problem 2: Persistent Slab
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Weak faceted snow that formed in December and January remains a concern above 10,000 ft in the Rock Creek area. Recent wind and 10-12" of new snow may have loaded some individual slopes enough that you could trigger a 2-4' deep avalanche if you hit the "sweet spot". You're most likely to find one of these weak spots on steep, upper north facing slopes near rocky ribs and below rocky ridgelines. 

recent observations

There was a natural avalanche cycle in the Negatives that occurred during the early morning hours yesterday. Wind transport made it hard to see old crown lines. 

Strong sun created stop and go conditions at the mid elevations except on shaded slopes. There were no natural avalanches reported in the Mammoth Lakes Basin. 

CURRENT CONDITIONS Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 16 deg. F.
Max. temperature in the last 24 hours: 28 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 35 mph
Maximum wind gust in the last 24 hours: 54 mph
New snowfall in the last 24 hours: trace inches
Total snow depth: 45 inches
weather

Snow is likely by mid day. Skies will be mostly cloudy, with a high near 25-30. Winds will be breezy, out of the southwest, blowing at 15 to 20 mph, with gusts as high as 30 mph. There is a 60% chance of snow up to 3 inches today. 

Tonight is the main storm event with 5 to 9 inches of snow possible above 9,000 ft. Tuesday will be snowy in the morning and partly cloudy by the afternoon. More snow is expected to fall Tuesday night. 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
  Monday Monday Night Tuesday
Weather: snow likely snow partly cloudy
Temperatures: 25 deg. F. 12 deg. F. 23 deg. F.
Wind direction: SW SW W
Wind speed: 15-20 20-25 10-15
Expected snowfall: 1-3 in. 5-9 in. 1-3 in.
Over 10,000 ft.
  Monday Monday Night Tuesday
Weather: snow snow partly sunny
Temperatures: 26 deg. F. 10 deg. F. 24 deg. F.
Wind direction: SW SW W
Wind speed: 15-20 25-40 15-20
Expected snowfall: 1-3 in. 5-9 in. 1-3 in.
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