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.

Another 1-3 inches of lighter snow fell across the forecast area yesterday. The winds shifted to the north and east last night. These northeast winds should remain light; snow showers should end this morning; and skies should start to clear today as a high-pressure ridge builds over the forecast area. This high-pressure should also bring slightly warmer temperatures to the region tomorrow.

Observations:

Yesterday, avalanches occurred on NE-facing, 37-40-degree, wind-loaded test-slopes in the Carson Pass area; on a 40-degree, N-facing, sparsely-treed slope on Fireplug in the Mt. Rose backcountry; on Donner Peak near Sugarbowl Academy; and on Mt. Rose proper. Skiers triggered all of these slides (more details, photos and videos). We do not have the details on the last two avalanches. No natural activity was reported yesterday. On Carson Pass and on the Fireplug the avalanches failed on the density change between the cold, light snow from last week and the new, heavy snow on top of it. This new, heavy snow served as the slab in both cases. Snowpit tests and observations on Jake's Peak and on Carson Pass showed weaknesses in the upper snowpack that broke in response to small amounts of force. One of these weaknesses was the density change between last week's snow and the new, heavy snow. The other was a density change within the new snow. Near the top of Jake's Peak the additional weight of a skier caused the snowpack to collapse in some areas.

Avalanche Concern #1:

Heavy wind slabs remain on top of lighter, weaker snow on wind-loaded slopes. Some settlement and consolidation in the snowpack over the last 24 hrs and the light to moderate northeast winds should make these slabs more difficult to trigger today. However, human-triggering of these wind slabs will remain possible. If these stiff wind slabs do break, they could still propagate large distances or break above the person who triggers them making escape from the slide more difficult. These wind slabs will most likely exist on wind-loaded, N-NE-E aspects steeper than 35 degrees near and above treeline. Pockets of fragile wind slabs could remain on cross-loaded NW and SE aspects. Large, heavy, and tender cornices will likely lurk above many of these slopes. Use clues like cornices, drifts, ripples, and other wind-created textures to help determine which slopes are wind-loaded.

Avalanche Concern #2:

The heavy, wet snow that sits on top of colder, lighter, weaker snow has created an upside-down snowpack in most of the forecast area. The additional weight of a person on the snow could still break the bonds holding these layers together resulting in avalanches involving the new snow. Open NW-N-NE-E aspects steeper than 37 degrees above and below treeline will hold best possibilities for these kinds of avalanches. Even though these avalanches should be harder to trigger today, they remain possible.

The bottom line:

Near and above treeline the avalanche danger is MODERATE on N-NE-E aspects 35 degrees and steeper. Near and above treeline pockets of MODERATE danger also exist on NW and SE aspects.  Below treeline pockets of MODERATE danger exist on open NW-N-NE-E aspects 37 degrees and steeper.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

Weather Observations from along the Sierra Crest between 8200 ft and 8800 ft:

0600 temperature:	24 deg. F.
Max. temperature in the last 24 hours:	31 deg. F.
Average wind direction during the last 24 hours:	Southwest shifting to the northeast after 1 am.
Average wind speed during the last 24 hours:	Southwest: 25 mph | Northeast: 5 mph mph
Maximum wind gust in the last 24 hours:	56 mph
New snowfall in the last 24 hours:	.5-2 inches
Total snow depth:	78-115 inches

Two-Day Mountain Weather Forecast - Produced in partnership with the Reno NWS

For 7000-8000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Mostly cloudy this morning becoming partly cloudy this afternoon.	Partly cloudy	Partly cloudy
Temperatures:	28-35 deg. F.	19-25 deg. F.	33-40 deg. F.
Wind direction:	Northeast	Northeast	Southeast
Wind speed:	10 mph	10 mph	10 mph
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Mostly cloudy this morning becoming partly cloudy this afternoon.	Partly cloudy	Partly cloudy
Temperatures:	27-33 deg. F.	17-24 deg. F.	36-42 deg. F.
Wind direction:	Northeast	Northeast	Northeast
Wind speed:	10-15 mph with gusts to 25 mph	10-15 mph with gusts to 25 mph	10 mph
Expected snowfall:	O in.	O in.	O in.