THIS AVALANCHE ADVISORY EXPIRED ON March 9, 2017 @ 6:43 am
Avalanche Advisory published on March 8, 2017 @ 6:43 am
Issued by Brandon Schwartz - Tahoe National Forest

MODERATE avalanche danger exists at all elevations. Loose wet avalanche problems will become increasingly widespread today. A wind slab avalanche problem may linger in isolated areas. Timing is important to avoid unstable wet snow as the loose wet problem will increase in response to daytime warming. Terrain with potential wind slabs will need evaluation on a slope by slope basis as signs of instability prior to an avalanche event will likely be very limited.

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

As the daily warming trend continues, natural and human triggered loose wet avalanche activity will be become increasingly widespread. Expect loose wet instability to form on E-SE-S-SW-W aspects at all elevations. Loose wet instability is also expected on NW-N-NE aspects at the low and mid elevations and potentially higher depending on sun exposure. Avalanche size could be large enough to bury a person, especially if a terrain trap is involved.

Avoid traveling on or under slopes 37 degrees and steeper where roller ball activity exists. Instability will increase as daytime warming progresses.

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

Numerous areas of blowing snow were observed yesterday near and above treeline but signs of unstable wind slabs were very limited. Lingering wind slab instability could still exist in isolated areas near and above treeline on NW-N-NE-E-SE-S aspects. Slopes directly below or adjacent to cornice features are the most suspect.

Any areas of instability will exist within greater surrounding areas of stable snow. Evaluate terrain on a slope by slope basis. Use accepted best practices for travel in or below avalanche terrain. Expose only one person at a time to slopes steeper than 35 degrees. Avoid relying on marginal islands of safety or regrouping in avalanche runout zones.

recent observations

Observations were made yesterday on Incline Lake Peak (Mount Rose area) and received from Shirley Canyon (near Squaw Valley). On Incline Lake Peak, blowing snow existed at treeline and plumes of blowing snow were visible off of the summits of surrounding above treeline peaks. Signs of wind slab instability were difficult to find in the snowpack with very limited and minor skier triggered cracking of surface wind slabs. Snowpit tests in a recently wind loaded area did not reveal signs of instability. In Shirley Canyon, significant warming and roller ball activity was reported on all aspects including true N below 7,700'. This was with moderate winds and significant cloud cover. Glide cracks up to 15 feet deep were noted as an additional hazard in the area.

Weather and CURRENT CONDITIONS
weather summary

High pressure continues to build over the forecast area as the storm track shifts to the north. The warming trend that began yesterday will continue through the next several days. Maximum daytime air temperatures above 7,000' are forecast to warm an additional 5 to 10 degrees over what occurred yesterday. Ridgetop winds out of the SW to W continued to decrease in speed over the past 24 hours. Light to moderate speed W winds are forecast for today and tomorrow.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 25 to 31 deg. F.
Max. temperature in the last 24 hours: 29 to 36 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 35 mph
Maximum wind gust in the last 24 hours: 78 mph
New snowfall in the last 24 hours: 0 to trace inches
Total snow depth: 138 to 197 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Wednesday Wednesday Night Thursday
Weather: Partly cloudy to possibly sunny skies. Partly cloudy skies, becoming clear. Sunny skies, becoming partly cloudy.
Temperatures: 36 to 46 deg. F. 24 to 34 deg. F. 40 to 50 deg. F.
Wind Direction: W W W
Wind Speed: Light winds Light winds Light winds
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Wednesday Wednesday Night Thursday
Weather: Partly cloudy to possibly sunny skies. Partly cloudy skies, becoming clear. Sunny skies, becoming partly cloudy.
Temperatures: 31 to 41 deg. F. 24 to 34 deg. F. 36 to 46 deg. F.
Wind Direction: W W W
Wind Speed: 15 to 20 mph. Gusts up to 40 mph. 10 to 15 mph with gusts to 30 mph. 10 to 15 mph with gusts to 30 mph.
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