THIS AVALANCHE FORECAST EXPIRED ON April 16, 2016 @ 6:46 am
Avalanche Forecast published on April 15, 2016 @ 6:46 am
Issued by Brandon Schwartz - Tahoe National Forest

Moderate avalanche danger exists for all elevations and aspects on slopes 35 degrees and steeper due to wind slab and loose wet avalanche problems. Locations in the northern portion of the forecast area will be most prone to these avalanche problems today. Locations in the southern portion of the forecast area where little to no new snow accumulated over the past 36 hours will have more limited loose wet avalanche problems today and no wind slab avalanche problems.

2. Moderate

?

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

2. Moderate

?

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

2. Moderate

?

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

In the northern portion of the forecast area, strong to gale force NE winds will redistribute the recent new snow on the ground and create fresh wind slabs in near treeline and above treeline areas on SE-S-SW-W-NW aspects today. These wind slabs are generally expected to be small in size, but could bury a person in a terrain trap. Some of these wind slabs could take on wet slab characteristics today.

Look for, identify, and avoid areas of potentially unstable wind slab. Use clues such as recent avalanche activity, blowing snow, new cornice and wind pillow formation, and human triggered snow surface cracking to determine where wind slabs exist.

Avalanche Problem 2: Loose Wet
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Loose wet avalanche problems are expected to form today in sun exposed areas on all aspects at all elevations. In locations with a couple inches or more of recent storm snow, loose wet avalanche problems are expected to form quickly this morning. Hard melt-freeze crust below the recent storm snow will act as an efficient bed surface for avalanche activity today allowing for the potential of long running avalanches. In areas where little to no recent storm snow exists and the snow surface is composed of hard melt-freeze crust, loose wet avalanche problems will form more slowly today, likely holding off until the afternoon hours.

In areas with recent storm snow, natural and human triggered roller balls and pinwheels will be the clues of developing wet snow instability. In areas without recent storm snow, loss of on foot supportability of the surface melt-freeze crust will indicate when the amount of surface wet snow is becoming problematic.

recent observations

Observations made yesterday on Andesite Ridge (Donner Summit area) revealed signs of instability were limited to loose dry avalanches. New snow amounts of 4 inches were present. Wind loading was isolated at 12 to 18 inches deep but did not extent more than 3 feet down slope. Bonding of new snow to the old snow melt-freeze crust surface was fairly poor, but some cohesion was observed. New snow was cohesive and moist but still acting like loose dry avalanches on test slopes in response to ski cuts. Sun breaks on the Sierra Crest yesterday morning were very infrequent and always lasted less than 3 minutes in the Donner Summit area. Despite the isolated periods of sun, a thin sun crust formed quickly in open areas on E-SE aspects.

Weather and CURRENT CONDITIONS
weather summary

The weather system that brought up to 4 inches of snow, mainly to the northern portion of the forecast area has exited the region. A significant NE wind event has begun as high pressure builds over the area. Air temperatures will remain on the cooler side today, but are still expected to reach above freezing in most locations. Decreasing winds and significant warming are expected going into the weekend.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 19 to 24 deg. F.
Max. temperature in the last 24 hours: 28 to 38 deg. F.
Average wind direction during the last 24 hours: SW shifting to NE
Average wind speed during the last 24 hours: SW 30 mph | NE 31 mph
Maximum wind gust in the last 24 hours: SW 59 mph | NE 51 mph
New snowfall in the last 24 hours: 0 to 1 inches
Total snow depth: 61 to 108 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy skies, becoming sunny. Isolated snow showers possible in the morning. Clear skies. Sunny skies.
Temperatures: 34 to 41 deg. F. 21 to 28 deg. F. 45 to 52 deg. F.
Winds: NE NE to E E
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy skies, becoming sunny. Isolated snow showers possible in the morning. Clear skies. Sunny skies.
Temperatures: 29 to 36 deg. F. 20 to 27 deg. F. 41 to 48 deg. F.
Winds: NE NE E
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

This avalanche advisory is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This advisory covers the Central Sierra Nevada Mountains between Yuba Pass on the north and Ebbetts Pass on the south. Click here for a map of the forecast area. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258