THIS AVALANCHE ADVISORY EXPIRED ON December 23, 2014 @ 7:12 am
Avalanche Advisory published on December 22, 2014 @ 7:12 am
Issued by Andy Anderson - Tahoe National Forest

The avalanche danger should remain LOW for all aspects and elevations today. Some small isolated loose wet snow instabilities may form due to daytime warming. In areas where the snowpack did not experience any overnight refreeze more loose wet snow instabilities may form. Southerly sun-exposed aspects hold the best possibility for these isolated wet snow instabilities.

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: Loose Wet
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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
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    Very Large
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    Small

Above freezing temperatures and some rain during the last 36 hours have created a layer of unconsolidated wet snow at the top of the snowpack on all aspects up to at least 9500 ft. This layer likely started to refreeze last night as heat from the snowpack escaped into the mostly clear night sky (radiational cooling) even though temperatures remained above freezing. Below the thin refrozen crust that may have formed last night, a layer of wet snow will remain. Since the sun is at its weakest and lowest and a strong north and east wind is expected today, daytime warming may not have the strength to melt through the thin refreeze. However, if today's warm temperatures and sunny skies today do melt last night's refreeze some small isolated human triggered loose wet avalanche activity like roller balls and pinwheels may become possible in isolated areas or extreme terrain especially on aspects facing the southern half of the compass.

recent observations

Yesterday, observers reported debris on N-NE-E aspects of Red Lake Peak that likely resulted from some large loose wet avalanches and smaller wind slab avalanches that occurred Saturday night or early Sunday morning. Another small avalanche occurred near Blue Lakes on an E aspect during that time frame due to the rapid warming.

During the day yesterday, observations from Red Lake Peak, Blue Lakes, Silver Peak, Andesite Ridge, and Tamarack Peak all revealed wet, heavy snow on all aspects up to 9500 ft. by midday. Before that time some frozen crusts existed above 9000 ft. on Red Lake Peak and Tamarack Peak. Drainage runnels existed on all aspects up to 9200 ft in these areas. Some small inconsequential human-triggered roller balls and pinwheels did occur in the Andesite Ridge, Tamarack Peak, and Silver Peak, areas on a few steep N-NE-E aspects. Snowpit data, ski and snowmobile cuts, and other observations did not reveal additional signs of instabilities in these areas yesterday.

Weather and CURRENT CONDITIONS
weather summary

Most remote sensors above 8000 ft. have been reporting a steady rise in temperatures for the last 36 hours. During that time temperatures have remained above freezing. This morning some of sensors at lower elevations and in the mountain valleys report cooler temperatures due to colder air settling into these low lying areas. Today's strong winds and sunny skies should cause this inversion to lift quickly. The winds shifted to the northeast last night and should remain strong over the ridge tops as a high pressure ridge moves into the region. These winds should begin to decrease tonight and tomorrow as the high pressure establishes itself over the area. This high pressure will bring sunny skies and continued warm temperatures to the forecast area through Wednesday.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 33 to 44 deg. F.
Max. temperature in the last 24 hours: 39 to 46 deg. F.
Average wind direction during the last 24 hours: Southwest shifting to Northeast
Average wind speed during the last 24 hours: 25 to 30 mph
Maximum wind gust in the last 24 hours: 92 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 24 to 37 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Sunny Clear Sunny
Temperatures: 42 to 50 deg. F. 26 to 36 deg. F. 41 to 48 deg. F.
Wind Direction: Northeast East East
Wind Speed: 5 to 15 mph 10 to 15 mph with gusts to 25 mph 10 to 15 mph with gusts to 25 mph becoming light in the afternoon
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Sunny Clear Sunny
Temperatures: 36 to 46 deg. F. 26 to 36 deg. F. 36 to 46 deg. F.
Wind Direction: North Northeast shifting to the east after midnight East
Wind Speed: 30 to 50 mph with gusts to 70 mph 30 to 45 mph with gusts to 65 mph decreasing to 30 to 35 mph with gusts to 50 mph after midnight 15 to 20 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.