THIS AVALANCHE ADVISORY EXPIRED ON February 27, 2016 @ 7:01 am
Avalanche Advisory published on February 26, 2016 @ 7:01 am
Issued by Andy Anderson - Tahoe National Forest

This morning the avalanche danger remains LOW for 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. Some small isolated wet snow instabilities may also form on northerly aspects. Most loose wet snow instabilities should remain small today but some could be large enough to pose a danger to backcountry travelers especially on slopes that receive direct sun and less wind today. 

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
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    Unlikely
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    Large
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Warmer overnight temperatures and some cloud cover means less refreezing occurred last night. Today the increased cloud cover and stronger winds should also make the melting side of the melt-freeze cycle less active. Still enough warming could occur today for loose wet snow instabilities like small roller balls, pinwheels, and wet point releases to form on some slopes especially in areas that receive direct sunshine and less wind. 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, but some wet snow could also form on more northerly aspects due to the increased cloud cover. 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 form good drainage channels and some decent corn snow conditions may exist. In still other areas like some of the exposed upper elevation slopes where the winds and cloud cover keep the snow surface cooler, the snow surface may remain mostly frozen today. 

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

Yesterday observations from Red Lake Peak, Angora Peak, and areas west of Carson Pass showed wet snow on sun-exposed aspects by 11 am. In some places like the more exposed ESE-SE-S aspects on Red Lake Peak this wet snow rested on top of a supportable melt-freeze snow that showed signs of well developed drainage. In other places like the E aspects of Angora Peak and some of the SE-S facing slopes west of Carson Pass the recent snow became wet and sticky and human triggered pinwheels and roller balls up to 3 ft. in diameter occurred. Observations from other aspects on Angora Peak showed firm icy frozen melt freeze crusts on W aspects before 1 pm and a mix of firm wind packed surfaces and patches of soft snow on exposed NW-N-NE aspects. Observations on the northerly aspects of Angora did not reveal any signs of instability. 

Weather and CURRENT CONDITIONS
weather summary

Another night above freezing at most elevations will transition into another warm day. The forecast calls for daytime highs slightly cooler than yesterday, but temperatures should still climb into the upper 40's to mid 50's above 7000 ft. A weak system passing to the north of the region has already led to an increase in cloud cover and stronger southwest winds. Today the forecast calls for partly cloudy skies with continued increasing southwest winds. This system also brings a 20% chance of precipitation in the form of very light rain and less than an inch of snow to the mountains north of I-80 tonight. South of I-80 the cloud cover and winds should represent the only impacts from this system. By tomorrow the winds should start to decrease again and colder air behind the weak disturbance will bring daytime highs down by ~5 degrees. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 39 to 43 deg. F.
Max. temperature in the last 24 hours: 49 to 55 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: Before 4am: 10 mph | After 4am: 20 mph
Maximum wind gust in the last 24 hours: 40 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.
Friday Friday Night Saturday
Weather: Partly cloudy with periods of full sun Partly cloudy becoming mostly cloudy with a slight chance of rain and a chance of rain and snow after midnight. Precipitation chances are mainly north of I-80 Partly cloudy becoming mostly cloudy
Temperatures: 49 to 56 deg. F. 30 to 35 deg. F. 43 to 50 deg. F.
Wind Direction: Southwest Southwest Southwest
Wind Speed: 10 to 15 mph increasing to 15 to 25 mph with gusts to 35 mph in the afternoon 15 to 25 mph with gusts to 40 mph increasing to 20 to 30 mph with gusts to 50 mph after midnight 10 to 20 mph with gusts to 30 mph
Expected snowfall: 0 in. trace to 0 in. 0 in.
For 8000 ft. to 9000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy with periods of full sun Partly cloudy becoming mostly cloudy with a slight chance of rain and snow and a chance of snow after midnight. Precipitation chances are mainly north of I-80 Partly cloudy becoming mostly cloudy
Temperatures: 41 to 49 deg. F. 25 to 30 deg. F. 35 to 43 deg. F.
Wind Direction: Southwest Southwest Southwest
Wind Speed: 20 to 30 mph increasing to 30 to 40 mph with gusts to 60 mph in the afternoon 35 to 50 mph with gusts to 75 mph 20 to 30 mph with gusts to 50 mph decreasing to 40 mph in the afternoon
Expected snowfall: 0 in. less than 1 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.