THIS AVALANCHE ADVISORY EXPIRED ON December 28, 2015 @ 6:50 am
Avalanche Advisory published on December 27, 2015 @ 6:50 am
Issued by Brandon Schwartz - Tahoe National Forest

MODERATE avalanche danger continues above treeline on all aspects and near treeline on NW-N-NE-E-SE-S aspects on slopes 35 degrees and steeper. For all other areas expect LOW avalanche danger. Wind slabs remain an ongoing problem with two small human triggered wind slab avalanches reported yesterday.

 

2. Moderate

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

2. Moderate

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

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    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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  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Visible blowing snow and significant amounts of wind loading were observed yesterday during the morning hours in the Mount Rose area and all day long along the Sierra Crest. Two human triggered wind slab avalanches were reported yesterday in near treeline terrain on E-SE-S aspects (more info below). In some areas winds were locally out of the S, creating additional wind loading on NW-N-NE aspects. Human triggering of small to medium size wind slabs will remain possible today in recently wind loaded areas. Use visual clues such as blowing snow, cornice formations, wind pillows, and sastrugi patterns on the snow surface to determine to the location of recently formed wind slabs.

recent observations

Yesterday on Silver Peak (Pole Creek area), significant amounts of blowing snow and active wind loading were observed on northerly aspects. In nearby Deep Creek, skier triggered shooting cracks up to 30 feet long were reported in N aspect near treeline terrain. Small skier triggered wind slab avalanches were reported from Ralston Peak (Desolation Wilderness area) and from Incline Lake Peak (Mount Rose area). On Ralston Peak the avalanche was reported on a SSE aspect near treeline at about 8,000'. On Incline Lake Peak the avalanche was reported on a wind loaded near treeline E aspect.

Snowpit data collected over the past several days indicates that deep persistent slab avalanches have become very unlikely.

Weather and CURRENT CONDITIONS
weather summary

An air temperature inversion set up last night with the warmest air temperatures over the past 24 hours occurring this morning at some locations in the mid and upper elevations. Maximum daytime air temperatures are forecast to reach the mid 20s to low 30s today for areas above 7,000'. Increasing cloud cover will occur today ahead of an approaching weak low pressure system that is expected to affect the forecast area over the next 24 hours. Ridgetop winds shifted from E to SW last night. Light to moderate speed SW winds are forecast for today and tonight, eventually shifting to the N tomorrow afternoon. A few inches of new snow are expected tonight through tomorrow morning. SW winds tonight are expected to mix out the inversion conditions. Maximum daytime air temperatures above 7,000' are forecast to be around 10 degrees colder for tomorrow than for today.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 19 to 28 deg. F.
Max. temperature in the last 24 hours: 21 to 30 deg. F.
Average wind direction during the last 24 hours: E
Average wind speed during the last 24 hours: 22 mph
Maximum wind gust in the last 24 hours: 71 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 50 to 61 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Sunday Sunday Night Monday
Weather: Partly cloudy skies, becoming mostly cloudy. Mostly cloudy skies with a slight chance of snow in the evening. Snow likely after midnight. Cloudy skies with snow likely in the morning. Scattered snow showers in the afternoon.
Temperatures: 26 to 33 deg. F. 9 to 17 deg. F. 18 to 25 deg. F.
Wind Direction: SW SW SW shifting to N in the afternoon.
Wind Speed: Light winds becoming 10 to 15 mph in the afternoon. 15 to 20 mph with gusts to 30 mph. 10 to 15 mph with gusts to 25 mph.
Expected snowfall: 0 in. Up to 2 in. 2 to 4 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Partly cloudy skies, becoming mostly cloudy. Mostly cloudy skies with a slight chance of snow in the evening. Snow likely after midnight. Cloudy skies with snow likely in the morning. Scattered snow showers in the afternoon.
Temperatures: 26 to 33 deg. F. 7 to 14 deg. F. 15 to 22 deg. F.
Wind Direction: SW SW W shifting to N in the afternoon.
Wind Speed: 15 to 20 mph with gusts to 35 mph. 20 to 30 mph with gusts to 45 mph. 20 to 25 mph with gusts up to 40 mph.
Expected snowfall: 0 in. Up to 2 in. 2 to 4 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.