THIS AVALANCHE ADVISORY EXPIRED ON December 6, 2015 @ 6:53 am
Avalanche Advisory published on December 5, 2015 @ 6:53 am
Issued by Brandon Schwartz - Tahoe National Forest

Avalanche danger is LOW for all elevations and aspects. Small isolated pockets of instability may linger both above and below treeline due to recently formed wind slabs and storm slabs. Normal caution is advised. Travel one at a time while in or below avalanche terrain. Avoid grouping up in marginal islands of safely or in avalanche run out zones. Maintain situational awareness and recognize the boundaries of avalanche terrain while on the fly.

 

1. Low

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Above Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Normal Caution
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  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Stubborn, difficult to trigger wind slabs are widespread in near and above treeline areas on NW-N-NE-E-SE aspects. Evaluate carefully any areas of recent wind loading, especially in complex terrain and near or above cliff bands. Wind slabs generally have visually discernable boundaries constrained by terrain features. Communicate with your partner(s) and know where the slab boundaries are.

Areas of problematic facets at the base of the snowpack near treeline and below treeline on NW-N-NE aspects are becoming increasingly few. However, unintentionally finding an isolated pocket that has remained unstable could certainly ruin your day. The overall snowpack is only 2-3 feet deep (or less) in most areas so evaluation requires little effort. A quick pole probe or boot post hole and subsequent hand pit will identify if you can make a snowball out of the softer snow at the base of the snowpack. It you find sugary grains that poorly form into a snowball, reevaluate your terrain choice.

recent observations

Observations made yesterday on Silver Peak (Pole Creek area), Rubicon Peak (West Shore Tahoe area), as well as those received from a partly on Red Lake Peak (Carson Pass area) all pointed towards minimal evidence of instability. Winds slabs in near and above treeline areas did not react to ski cuts or provide unstable results in snowpit tests. Snowpit data collected yesterday on Silver Peak and Rubicon Peak as well as recent snowpit data from the Donner Summit, Mount Rose, and Carson Pass areas (more info below) have all indicated increasing strength within what was faceted snow crystals located either at the base of the snowpack or within the snowpack near treeline and below treeline on NW-N-NE aspects. Significant warming, rounding, and a decrease in unstable snowpit test results has been observed within these layers over the past few days.

Weather and CURRENT CONDITIONS
weather summary

Weak high pressure with cloud cover today combined with SW flow aloft will allow for above freezing air temperatures at the mid and upper elevations. A storm system passing to the north of the forecast area tomorrow will bring an increase in S to SW winds tonight into tomorrow. A chance of light snowfall is forecast for tomorrow mainly north of I-80, with chances decreasing down towards Hwy 50 and points south. Strong to gale force SW winds tonight and tomorrow should keep the atmosphere well mixed and prevent any inversion from forming in the mountain valleys Sunday morning. A warming trend is expected for the early part of next week before the likely return to a stormy weather pattern.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 22 to 31 deg. F.
Max. temperature in the last 24 hours: 25 to 34 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 19 mph
Maximum wind gust in the last 24 hours: 32 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 19 to 24 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy skies. Mostly cloudy skies. Mostly cloudy skies. A chance of snow.
Temperatures: 36 to 43 deg. F. 29 to 34 deg. F. 35 to 42 deg. F.
Wind Direction: S S SW
Wind Speed: Light winds becoming 10 to 20 mph with gusts to 30 mph in the afternoon. 15 to 25 mph. Gusts to 45 mph. 30 to 40 mph with gusts to 60 mph.
Expected snowfall: 0 in. 0 in. Up to 1 in.
For 8000 ft. to 9000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy skies. Mostly cloudy skies. Mostly cloudy skies. A chance of snow.
Temperatures: 35 to 42 deg. F. 28 to 32 deg. F. 35 to 43 deg. F.
Wind Direction: SW S shifting to SW SW
Wind Speed: 10 to 15 mph increasing to 20 to 35 mph with gusts to 45 mph in the afternoon. 30 to 40 mph with gusts to 70 mph, shifting and increasing to 45 to 60 mph with gusts to 85 mph after midnight. 45 to 60 mph with gusts to 90 mph, decreasing to 35 to 50 mph with gusts to 70 mph in the afternoon.
Expected snowfall: 0 in. 0 in. Up to 1 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.