THIS AVALANCHE FORECAST EXPIRED ON March 8, 2019 @ 6:59 am
Avalanche Forecast published on March 7, 2019 @ 6:59 am
Issued by Andy Anderson - Tahoe National Forest - Sierra Avalanche Center

MODERATE avalanche danger exists at all elevations today due to wind slab and storm slab avalanche problems. Human-triggered avalanches large enough to have consequences remain possible today. If the clouds part today, the strong March sunshine could exacerbate the existing avalanche problems and could allow wet snow instabilities to form. 

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-loaded N-NE-E aspects and cross-loaded NW and SE aspects in near and above treeline terrain should hold the largest slabs of wind drifted snow. Some additional snow and wind today could cause these slabs to continue increasing in size and extent. Adding the weight of a person to these wind-loaded slopes could trigger a wind slab avalanche today. These avalanches may entrain enough snow to bury, injure, or kill a person. If the sun makes an appearance today, some of these wind slabs could be easier to trigger on sun-exposed slopes.

Maintain awareness of the conditions and terrain by using clues like cornices above a slope, blowing snow, drifted snow, and other wind created surface textures to locate potential wind slabs. This information will also help find softer non-wind-affected snow where recreation conditions may be more fun and less avalanche concerns exist.

Avalanche Problem 2: Storm Slab
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As the storm snow begins to settle and consolidate, storm slab avalanches should become more difficult to trigger in most places. However, human-triggered storm slab avalanches may remain possible today in some areas. Many of these soft slabs should remain small and only involve the new snow. Steep open slopes in sheltered terrain have the potential to hold lingering storm slabs. If the strong March sunshine breaks through the clouds today, some storm slabs may release more easily or loose wet snow instabilities may form on sun-exposed slopes. 

Signs that storm snow weaknesses may remain active include shooting cracks and recent avalanche activity. Features of concern could include areas with convex rollovers, terrain traps, and areas of more complex terrain. Identifying these areas can help maintain an appropriate safety margin. 

recent observations

* Yesterday natural wind slab and storm slab avalanches occurred on Incline Lake Peak and on Tamarack Peak. The storm slabs failed on a layer of lower density snow about 8 to 12 inches below the surface. Some of the wind slabs had 1 to 2 ft crowns. 

* Skier triggered wind slabs of similar size also occurred on test slopes on Tamarack Peak and Andesite Peak.

* Observers reported continuous blowing snow on Donner Summit, in the Mt. Rose backcountry, and on Echo Summit. 

Weather and CURRENT CONDITIONS
weather summary

Most remote sensors reported 9 to 11 inches of new snow in the last 24 hours with a few reporting 14 to 16 inches. Precipitation intensity peaked during the day yesterday. Snow levels and temperatures have been steadily falling since yesterday afternoon with snow levels now below 6000 ft. Temperatures should remain below normal. The forecast calls for more snow showers today with another few inches of accumulation. Some showers may linger into tomorrow evening. The gale force SW winds should decrease in strength today but still remain strong enough to transport snow in many areas.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 22 to 27 deg. F.
Max. temperature in the last 24 hours: 30 to 34 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 55 to 60 mph
Maximum wind gust in the last 24 hours: 132 mph
New snowfall in the last 24 hours: 9 to 16 inches
Total snow depth: 121 to 135 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Mostly cloudy. Chance of snow showers. Snow levels below 7000 feet. Chance of precipitation is 60%. Cloudy. Chance of snow showers. Snow levels below 7000 feet. Chance of precipitation is 55%. Mostly cloudy. Chance of snow showers. Snow levels below 7000 feet. Chance of precipitation is 35%.
Temperatures: 32 to 38 deg. F. 16 to 21 deg. F. 24 to 29 deg. F.
Mid Slope Winds: Southwest 15 to 25 mph with gusts to 45 mph. Southwest 15 to 20 mph with gusts to 35 mph. Southwest around 15 mph with gusts to 30 mph.
Expected snowfall: 80% probability of 1 to 3 inches. 20% probability of 3 to 5 inches. | SWE = up to 0.20 inch. 60% probability up to 2 inches. 40% probability of 2 to 4 inches. | SWE = up to 0.15 inch. 40% probability up to 1 inch. 60% probability of no accumulation. | SWE = less than 0.10 inch.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Mostly cloudy. Chance of snow showers. Snow levels below 7000 feet. Chance of precipitation is 80%. Cloudy. Snow showers likely. Snow levels below 7000 feet. Chance of precipitation is 60%. Mostly cloudy. Chance of snow showers. Snow levels below 7000 feet. Chance of precipitation is 35%.
Temperatures: 26 to 32 deg. F. 13 to 18 deg. F. 19 to 25 deg. F.
Ridge Top Winds: Southwest 20 to 35 mph with gusts to 65 mph. Southwest 15 to 30 mph. Gusts up to 50 mph decreasing to 40 mph after midnight. Southwest 15 to 25 mph with gusts to 40 mph.
Expected snowfall: 70% probability of 2 to 4 inches. 30% probability of 4 to 6 inches. | SWE = up to 0.25 inch. 80% probability of up to 3 inches. 20% probability 3 to 5 inches. | SWE = up to 0.20 inch. 40% probability up to 1 inch. 60% probability of no accumulation. | SWE = less than 0.10 inch.
Disclaimer

This avalanche forecast is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This forecast 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 forecast applies only to backcountry areas outside established ski area boundaries. This forecast describes general avalanche conditions and local variations always occur. This forecast expires 24 hours after the posted time unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the avalanche forecast call (530) 587-3558 x258