THIS AVALANCHE ADVISORY EXPIRED ON February 26, 2016 @ 7:37 am
Avalanche Advisory published on February 25, 2016 @ 7:37 am
Issued by Andy Anderson - Tahoe National Forest

This morning LOW avalanche danger exists on all elevations and aspects. MODERATE avalanche danger will form on E-SE-S-SW-W aspects steeper than 35 degrees as human triggered loose wet avalanches become possible due to daytime warming. Small roller balls, pinwheels, and loose wet point releases will represent the majority of the loose wet instabilities today but some of them could be large enough to pose a danger to backcountry travelers. 

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.

2. Moderate

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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
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    Certain
    Very Likely
    Likely
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    Unlikely
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Even though overnight lows remained above freezing in many places, the snowpack should have radiated enough heat out into the clear night sky for a weak overnight refreeze. Today's plentiful sunshine and warm daytime temperatures will quickly melt through this weak refreeze and allow loose wet snow avalanches to become possible. While most of these loose wet snow instabilities will manifest as small roller balls, pinwheels, and loose wet point releases, some of them could entrain enough snow to cause problems for backcountry travelers. Sun-exposed E-SE-S-SW-W aspects steeper than 35 degrees where the recent snow has not been through enough melt freeze cycles to create good drainage channels in the snow hold the best potential for loose wet avalanches today. In some areas where less new snow existed or where firm wind packed or scoured surfaces existed after the recent storm, the surface snow has already experienced enough melt-freeze cycles to become corn snow and loose wet snow instabilities may be less common on these slopes. 

Sinking into wet snow above boot-top height, small surface wet snow instabilities like pinwheels or roller balls, and other recent loose wet snow avalanches can all indicate that enough wet snow exists for problematic loose wet avalanches to occur. These clues usually indicate that the snow conditions have become less fun to recreate on as well. At this point finding a more frozen aspect or switching activities represents a great way to stay safe and keep having fun. 

recent observations

Daytime warming and sunshine created wet snow on sun-exposed SE-S-SW aspects by mid morning on Castle Peak (Donner Summit area), Gold Peak (north of Squaw), the west side of Carson Pass, and on Fireplug (Mt. Rose backcountry). On some exposed upper elevation slopes on Castle Peak, the west side of Carson Pass, and Fireplug that experienced more wind scouring and less snow during the recent storm, 2 to 6 inches of wet snow existed on top of a supportable firm surface. In these areas and on Gold Peak, deep wet, sticky, and punchy snow existed on other upper elevation slopes and on lower elevation or more sheltered slopes. Human triggered roller balls and pinwheels up to 3 ft in diameter occurred on Gold Peak and on Fireplug. Observations and tests on northerly aspects on Castle Peak and Fireplug showed a mix of firm wind packed surfaces and cold soft snow and did not reveal any signs of instability. 

Weather and CURRENT CONDITIONS
weather summary

Calm clear weather last night allowed cold air to settle into the lower elevations while the upper elevations stayed warm. Remote sensors above 8000 ft. reported temperatures in the mid 30's to low 40's as of 6 am this morning with the lower elevation sensors reading 5 to 10 degrees cooler. This inversion should lift today as the high pressure parked over the region brings more sunny warm weather. The forecast calls for daytime highs in the upper 40's to mid 50's above 7000 ft. today. A small weak system passing to the north of the forecast area tomorrow should bring slightly cooler temperatures, an slight increase in cloud cover, stronger southwest winds, and a slight chance of some light precipitation north of I-80 tomorrow. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 34 to 42 deg. F.
Max. temperature in the last 24 hours: 44 to 51 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 10 to 15 mph
Maximum wind gust in the last 24 hours: 43 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 56 to 87 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Sunny becoming partly cloudy for part of the afternoon Clear to partly cloudy Sunny becoming partly cloudy
Temperatures: 50 to 56 deg. F. 31 to 37 deg. F. 49 to 55 deg. F.
Wind Direction: Variable Southwest Southwest
Wind Speed: 10 mph Light increasing to 10 to 15 mph after midnight 10 to 20 mph with gusts to 30 mph increasing to 15 to 25 mph with gusts to 45 mph in the afternoon
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Sunny becoming partly cloudy for part of the afternoon Clear to partly cloudy Sunny becoming partly cloudy
Temperatures: 45 to 50 deg. F. 30 to 35 deg. F. 43 to 49 deg. F.
Wind Direction: Southwest Southwest Southwest
Wind Speed: 10 to 15 mph 10 to 15 mph increasing to 15 to 25 mph with gusts to 40 mph after midnight 20 to 30 mph with gusts to 45 mph increasing to 30 to 45 mph with gusts to 75 mph in the afternoon
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.