THIS AVALANCHE ADVISORY EXPIRED ON March 3, 2015 @ 6:40 am
Avalanche Advisory published on March 2, 2015 @ 6:40 am
Issued by Brandon Schwartz - Tahoe National Forest

Pockets of MODERATE avalanche danger linger near and above treeline on all aspects on slopes 35 degrees and steeper due to recently formed wind slabs. Pockets of MODERATE danger are possible above 8,000' in near and below treeline terrain on NW-N-NE aspects on slopes 35 degrees and steeper due to potential developing persistent slabs. For all other areas, avalanche danger is LOW. Thoughtful, deliberate decision making remains paramount for avoiding human triggered avalanches in the backcountry 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: Wind Slab
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Wind slabs that formed within the past 24 to 60 hours will continue to gain strength. Difficult to trigger wind slabs generally 1 to 3 feet thick linger on all aspects in near and above treeline terrain due to shifting winds over the past two nights. These wind slabs are stiff and easily identified along ridgetops as pillows directly below small cornice and wind features. Avoidance or alternate slope entry/exit locations are the best mitigation options when areas of cracking are observed around these wind slabs. Glossary of terms

Avalanche Problem 2: Persistent Slab
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Persistent slabs are a developing concern above 8,000' in near treeline and below treeline terrain on NW-N-NE aspects. In these northeast wind protected areas, near surface facets have been observed at the old/new snow interface. The concern focus on an intensification of stress at the base of the recent new snow. As the recent storm snow settles, bonds, and gains strength, the area of greatest relative weakness within the snowpack will shift down to buried near surface facets at the base of the storm snow. This may actually lead to a decrease in stability over what was observed the past two days. This also means that previous tracks on a slope from the past two days will have no bearing on current slope stability as the snowpack is changing daily. Handpits will easily detect the presence or absence of near surface facets at the base of the storm snow. Snowpit tests will indicate if and when this layer interface is becoming problematic. Glossary of terms

recent observations

Observations made yesterday on Silver Peak (Pole Creek area) revealed a slow to settle snowpack on northerly aspects and a rapidly settling snowpack on solar aspects. Significant areas of melt were noted to occur during the day below 7,000'. The recent new snow was decently well bonded to rain crust on northerly aspects. No evidence of buried near surface facets at the old/new snow interface was found below the high point of travel at 8,000'. This matched well with the known distribution of buried near surface facets in other locations around the forecast area. Snowpit tests performed at 8,000' on a N aspect near treeline indicated that minimal weakness remained within the recent storm snow and that it was slowly becoming increasingly cohesive. Wind slabs with minimal skier triggered cracking were observed along ridgetops, only extending a short distance down slope. Glossary of terms

Weather and CURRENT CONDITIONS
weather summary

A weather system will bring mostly cloudy skies and snow showers to the forecast area today. Snow showers are expected to start this morning, becoming more widespread this afternoon. New snow amounts of a trace to 2 inches are expected for most areas with a few inches more possible in localized areas under convective cells. Remote sensors are reporting air temperatures this morning in the low 20s at 8,000' to 9,000' with minimal inversion conditions. Maximum daytime air temperatures are forecast to reach the upper 20s to low 30s today for areas above 7,000'. Ridgetop winds shifted from northeast to southwest last night and remain moderate in speed. Winds are forecast to shift back to the north to northeast tonight.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 20 to 23 deg. F.
Max. temperature in the last 24 hours: 26 to 28 deg. F.
Average wind direction during the last 24 hours: Northeast shifting to southwest
Average wind speed during the last 24 hours: 29 mph
Maximum wind gust in the last 24 hours: 54 mph
New snowfall in the last 24 hours: 0 to 1 inches
Total snow depth: 40 to 51 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy skies. Scattered snow showers in the morning, becoming more widespread in the afternoon. Mostly cloudy skies, becoming partly cloudy. Scattered snow showers in the evening. Partly cloudy skies.
Temperatures: 27 to 34 deg. F. 11 to 18 deg. F. 30 to 37 deg. F.
Wind Direction: W W N
Wind Speed: Light winds increasing to 10 to 15 mph with gusts to 25 mph in the afternoon. 10 to 15 mph. Gusts to 25 in the evening. 5 to 15 mph.
Expected snowfall: Trace to 2 in. Trace to 1 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy skies. Scattered snow showers in the morning, becoming more widespread in the afternoon. Mostly cloudy skies, becoming partly cloudy. Scattered snow showers in the evening. Partly cloudy skies.
Temperatures: 26 to 32 deg. F. 10 to 17 deg. F. 26 to 32 deg. F.
Wind Direction: W NW N to NE
Wind Speed: 15 to 25 mph with gusts up to 35 mph. 20 to 30 mph with gusts to 35 mph. 20 to 35 mph with gusts to 50 mph.
Expected snowfall: 1 to 2 in. Trace to 2 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.