THIS AVALANCHE ADVISORY EXPIRED ON December 25, 2014 @ 6:51 am
Avalanche Advisory published on December 24, 2014 @ 6:51 am
Issued by Andy Anderson - Tahoe National Forest

This morning the avalanche danger will remain LOW for all aspects and elevations. As new snow and wind impact the region this afternoon and evening, the avalanche danger will quickly rise to MODERATE on wind-loaded NW-N-NE-E-SE aspects steeper than 35 degrees in near and above treeline terrain. Human-triggered avalanches could become possible this afternoon and evening.

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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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

As new snow starts to fall this afternoon, new wind slabs will form quickly on the leeward aspects in near and above treeline terrain. Due to intense snowfall rates and strong winds, these new wind slabs will likely build faster than the bonds between the new snow layers can form. Human-triggered wind slab avalanches will become possible this afternoon and evening. Any avalanches that result from these wind slabs should start out small, but will grow larger as new snow accumulates this afternoon and evening. These winds slabs should only involve the new snow, and avalanches breaking into the old snow will remain unlikely.

recent observations

Yesterday observations on Red Lake Peak and on Tamarack Peak both indicated that the snowpack continues to consolidate and settle. Data indicates that the current snowpack is in good shape to handle the additional new load expected in the next 24 hrs.

Surface conditions in these two areas yesterday ranged from firm supportable crusts to breakable crusts to wet, sticky unsupportable snow to some areas of corn-like conditions.

Weather and CURRENT CONDITIONS
weather summary

Winds started increasing overnight ahead of an approaching cold front. They should shift to the southwest today and continue to increase. Temperatures should begin to fall today with daytime highs in the upper 30's to mid 40's occurring this morning. By this afternoon expect daytime temperatures between 25 and 32 degrees above 7000 ft. The forecast calls for precipitation to start this afternoon. The precipitation should start as rain in many areas, but as the cold front pushes colder air into the region snow levels should fall quickly dropping below 4000 ft. by this evening. The forecast calls for 2 to 4 inches of snow this afternoon with another 4 to 8 inches this evening. The heaviest snowfall should occur between 3 pm and 10 pm with snowfall rates of 2-3 in/hr at times. Some thunderstorms may be possible during the periods of heaviest precipitation. This front should continue out of the area during the night leaving cold air and north to northeast winds in its wake. Snowfall should taper off after midnight, and the forecast calls for partly cloudy skies tomorrow.  

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 32 to 42 deg. F.
Max. temperature in the last 24 hours: 49 to 55 deg. F.
Average wind direction during the last 24 hours: West
Average wind speed during the last 24 hours: 15 to 25 mph
Maximum wind gust in the last 24 hours: 41 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 23 to 36 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Wednesday Wednesday Night Thursday
Weather: Cloudy with snow in the afternoon. Slight chance of thunderstorms in the afternoon. Snow with a slight chance of thunderstorms in the evening becoming partly cloudy with a slight chance of snow showers after midnight. Partly cloudy
Temperatures: 39 to 46 deg F. falling to near 28 to 32 deg. F. 11 to 18 deg. F. 17 to 24 deg. F.
Wind Direction: Southwest North Northeast
Wind Speed: 15 to 25 mph with gusts to 55 mph 10 to 20 mph 10 to 20 mph with gusts to 30 mph
Expected snowfall: 2 to 4 in. 4 to 7 in. 0 in.
For 8000 ft. to 9000 ft.
Wednesday Wednesday Night Thursday
Weather: Cloudy with snow in the afternoon. Slight chance of thunderstorms in the afternoon. Snow with a slight chance of thunderstorms in the evening becoming partly cloudy with a slight chance of snow showers after midnight. Partly cloudy
Temperatures: 35 to 40 deg F. falling to 25 to 30 deg. F. 8 to 15 deg. F. 13 to 20 deg. F.
Wind Direction: Southwest North Northeast
Wind Speed: 40 to 45 mph with gusts to 70 mph increasing to 65 to 70 mph with gusts to 105 mph in the afternoon 35 to 45 mph with gusts to 65 mph 20 to 30 mph with gusts to 45 mph
Expected snowfall: 2 to 4 in. 4 to 8 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.