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.

A storm system north of the area should continue to push cloud cover into the region today. Most of the precipitation associated with this system should stay north of the area until tonight when it moves closer to Tahoe. At this point some snow should start to occur over the forecast area. The forecast calls for snow levels to rise to 7000 ft tomorrow as this system pulls warmer air over the region. Near and below 7000 ft, much of tomorrow's precip could fall as rain. Above 7000 ft most of it should fall as snow. The NWS expects up to 8 inches of total snow accumulation by tomorrow evening. The southwest winds have already started to increase ahead of this system. They should continue to strengthen through tonight before decreasing some during the day tomorrow.

Observations:

On Angora Peak and on Castle Peak yesterday, stability tests and snowpit data indicated a mostly stable snowpack with good bonding both within and between the layers. Snowpits in both of these areas still showed a layer of heavier snow on top of a small layer of lighter snow; however, the bonds holding these layers together seem to be gaining strength (pit profile from Castle). In both of these areas, ski cuts on steep, wind-loaded NW-N-NE aspects did not result in any signs of instability in the snowpack. South of Angora Peak on Echo Peak several large cornice pieces had recently broken off an fallen onto the slopes below where they failed to cause any avalanches (photos). In the Castle Peak area, oven to large sofa sized cornice pieces pushed onto the slopes below also did not cause any avalanche activity. 

Some roller balls did occur on a sun-exposed, S facing slope at around 8000 ft on Castle Peak. These roller balls only reached around 6-8 inches in diameter and released naturally  due to daytime warming at 11:30 am.

Primary Avalanche Concern: Warming Instabilities

Sunshine and daytime highs in the mid 30's to 40's above 7000 ft. should cause enough melting for some instabilities to form due to daytime warming. The increased cloud cover and winds forecasted for today will work against these warming influences and should keep any instabilities that do form small in size. Roller balls and small point release sluffs should comprise most of these instabilities today. Most of these should not entrain enough snow to bury a person, but some of the larger ones could could knock someone over or push him/her off course which may have more serious consequences depending on the terrain. On the most open, sun-exposed SE-S-SW aspects, slab avalanches due to daytime warming may become possible. 

Other avalanche concerns: Older Wind Slabs

Recent observations show continued settlement and consolidation within the snowpack. In most areas the bonds between the old snow and the wind slabs on top of it have strengthened enough to hold the snowpack in place. Avalanche activity involving these wind slabs will be unlikely but not impossible today. Continue to use caution around wind-loaded NW-N-NE-E aspects near and above treeline especially in complex or extreme terrain.

The bottom line:

Pockets of MODERATE avalanche danger may form today on SE-S-SW aspects on slopes 37 degrees and steeper in response to daytime warming at all elevations. On the more northerly aspects, LOW avalanche danger exists at all elevations. LOW danger does not mean that avalanche activity is impossible. Continue to use caution when traveling in the backcountry.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	22-23 deg. F.
Max. temperature in the last 24 hours:	29-39 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	30 mph
Maximum wind gust in the last 24 hours:	59 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	91-132 inches

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

For 7000-8000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Partly cloudy this morning becoming cloudy with a slight chance of snow in the afternoon	Chance of snow in the evening then snow after midnight	Rain and snow. Snow levels around 7000 ft.
Temperatures:	35-45 deg. F.	23-33 deg. F.	34-44 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	20-30 mph with gusts to 50 mph	20-30 mph with gusts to 60 mph decreasing to 45 mph after midnight	20-30 mph with gusts to 55 mph
Expected snowfall:	O in.	up to 3 in.	up to 5 in.
For 8000-9000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Partly cloudy this morning becoming cloudy with a slight chance of snow in the afternoon	Chance of snow in the evening then snow after midnight	Snow
Temperatures:	26-36 deg. F.	20-30 deg. F.	25-35 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	30-45 mph with gusts to 70 mph	30-50 mph with gusts to 80 mph decreasing to 65 mph	30-45 mph with gusts to 70 mph
Expected snowfall:	O in.	up to 3 in.	up to 5 in.