THIS AVALANCHE ADVISORY EXPIRED ON March 2, 2014 @ 7:00 am
Avalanche Advisory published on March 1, 2014 @ 7:00 am
Issued by Andy Anderson - Tahoe National Forest

MODERATE danger exists on slopes 35 degrees and steeper on wind loaded W-NW-N-NE-E-SE aspects in near and above treeline terrain. Some pockets of CONSIDERABLE danger may still lurk on those same aspects and elevations south of Hwy. 50 where more snow fell. Pockets of MODERATE avalanche danger may also remain on some slopes 35 degrees and steeper on NW-N-NE-E aspects in near and below terrain. Human triggered wind slab and storm slab avalanches remain possible today.

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Human triggered wind slab avalanches will remain possible today. The largest and most fragile wind slabs will exist on leeward slopes in near and above treeline terrain south of Hwy. 50 where much more snow fell. In some of these areas human triggered wind slabs may remain likely. The most recent wind slabs have formed on top of a mix of older wind slabs and lighter snow layers. Underneath these layers old crusts, layers of weak sugary snow, and layers of lighter storm snow still remain. Most of the wind slabs that fail today should do so at or above the interface between Wednesday night's snow and yesterday's snow (1-3 ft from the surface). However, some of them could step down the the old snow layers below Wednesday night's snow making them much deeper. Due to the shifting south and southwest winds the wind slabs could exist on W-NW-N-NE-E-SE aspects in near and above treeline terrain.

Avalanche Problem 2: Storm Slab
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Some fragile storm slabs could still lurk on the below treeline NW-N-NE-E aspects where thin layers of soft sugary snow exist below the new snow that has fallen since Wednesday night and where shallower storm snow weaknesses may remain within the recent snow. Human triggered storm slab avalanches may remain possible in these areas. These slabs could measure 1 to 2+ ft. in depth. The deepest and most fragile of these storm slabs will likely exist on sheltered N aspects above 8000 ft. As with the wind slabs areas south of Hwy. 50 will be the most suspect due to the fact that they received much more snow.

recent observations

Yesterday observations along the Becker Peak/Talking Mtn. ridgeline revealed new, fragile wind slabs on wind loaded N-NE aspects in near and and above treeline terrain. By mid day some of these wind slabs had reached 16 inches in depth even though only 3-4 inches of snow had fallen. Stomping on ridgelines near these wind slabs or dropping small oven sized cornice pieces on the wind loaded slopes triggered small wind slab avalanches in this area. In addition to these intentionally human-triggered slides one small natural wind slab avalanche occurred in this area yesterday. All of these slabs measured between 6 and 16 inches in depth and failed at the interface between the snow that fell yesterday and the snow that fell on Wed. night.

Below 7600 ft. near Echo Lake, heavy wet snow existed and ski cuts could trigger minor roller balls on N-NE aspects. In this area and farther north on Andesite Ridge a period of sunshine in the morning and warming temperatures did cause the surface snow on sun exposed aspects up to 8200 ft. to also become wet and heavy during the morning yesterday.

Weather and CURRENT CONDITIONS
weather summary

North of Hwy. 50, 6-8 inches of new snow has fallen above 7000 ft. in the last 24 hrs. South of Hwy. 50, almost twice that amount fell with remote sensors showing 11-15 inches of new snow since 6 am yesterday. Light snow showers should continue today under cloudy skies as the low pressure associated with this storm continues to move south and east. Moderate to strong south to southwest winds should also persist this morning. By this afternoon snow showers should begin to taper off and the winds should start to decrease.  Some clouds and isolated showers could remain through tonight, but no accumulation is expected. Tomorrow's forecast calls for cloud cover, snow showers, and winds to continue to decease. Daytime highs tomorrow should also start to warm back up.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 21 to 26 deg. F.
Max. temperature in the last 24 hours: 29 to 36 deg. F.
Average wind direction during the last 24 hours: Varying between southeast, south and southwest
Average wind speed during the last 24 hours: 25 to 30 mph
Maximum wind gust in the last 24 hours: 87 mph
New snowfall in the last 24 hours: North of Hwy 50: 6 to 8 inches| South of Hwy 50: 11 to 15 inches
Total snow depth: 49 to 64 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Saturday Saturday Night Sunday
Weather: Cloudy with some snow showers Mostly cloudy with isolated snow showers Mostly cloudy with a slight chance of snow showers
Temperatures: 30 to 36 deg. F. 19 to 26 deg. F. 32 to 39 deg. F.
Wind Direction: South Southwest Southwest
Wind Speed: 20 to 25 mph with gusts to 40 mph decreasing to 10 to 15 mph with gusts to 25 mph in the afternoon Light winds in the evening increasing to 10 to 15 mph after midnight. 15 to 20 mph with gusts to 30 mph
Expected snowfall: up to 2 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Saturday Saturday Night Sunday
Weather: Cloudy with some snow showers Mostly cloudy with isolated snow showers Mostly cloudy with a slight chance of snow showers
Temperatures: 27 to 32 deg. F. 18 to 25 deg. F. 33 to 39 deg. F.
Wind Direction: Southwest shifting to the south in the afternoon Southwest Southwest
Wind Speed: 35 to 40 mph with gusts to 60 mph decreasing to 15 to 20 mph with gusts to 35 mph in the afternoon 15 to 20 mph with gusts to 30 mph 20 to 30 mph with gusts to 35 mph increasing to gusts to 45 mph in the afternoon
Expected snowfall: up to 2 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.