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.

Any clouds that remain over the region today should start to disperse tonight as the low pressure system south of the area moves eastward. A high pressure ridge should move back into the forecast area bringing back more clear skies and slightly warmer temperatures for today and tomorrow. Daytime highs should climb about five degrees over yesterday's highs and reach into the upper 20's and low 30's. The winds have shifted back to the east and northeast and should remain light and variable shifting from the east to the southwest by tomorrow afternoon.

Observations:

Yesterday on Castle Peak, observations showed a variety of snowpack conditions on the NW-N-NE-E aspects (more info, snowpit, and video). In some areas NE winds had scoured all of the snow away leaving behind bare ground. In more sheltered places above 7500 ft, continued faceting (a process that weakens snow) had changed the entire snowpack, crusts and wind slabs included, into weak, unconsolidated snow. On some of the more exposed but not completely scoured slopes, hard slabs existed on top of the snowpack with a layer of weak facets (the Nov 18th facets) on the bottom of the snowpack. In these areas snowpit data and tests indicated that once a fracture starts in the facets, it can travel through that layer (video). In this area the strength of the hard slab could hold the snowpack together, at least for now. On many other slopes a very shallow snowpack existed with lots of anchors poking through it. Observations indicate similar conditions exist across the forecast area. The northerly aspects north of I-80 hold the most snow at this time.

Avalanche Concerns: Persistent slabs

Over the last few weeks, continued faceting or wind scouring has destroyed most of the slabs that once existed on top of the snowpack. Wind scouring even removed the persistent weak layer at  the base of the snowpack in some areas. On many slopes anchors poking through the snowpack disrupt the weak layer and hold the snow above it in place. These things have made avalanche activity unlikely in most areas for now. They have not removed the persistent weak layer completely, and it will remain weak for the foreseeable future. Even though avalanches are unlikely, they are not impossible. Some isolated areas where hard slabs have survived still exist. Weak faceted snow exists under these hard slabs. On the few slopes without many anchors extending through the snowpack, the right trigger in the right place may be enough to break one of these slabs loose. Very few of these areas remain, and they exist in areas of seemingly stable snow. Travel smart and exercise appropriate caution in the backcountry in order to minimize risk.

The bottom line:

Avalanche danger is LOW for all elevations and aspects. Normal caution is advised.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	18 deg. F.
Max. temperature in the last 24 hours:	24 deg. F.
Average wind direction during the last 24 hours:	East
Average wind speed during the last 24 hours:	20 mph
Maximum wind gust in the last 24 hours:	42 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	6-20 inches

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

For 7000-8000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Partly cloudy	Clear	Partly cloudy
Temperatures:	24-31 deg. F.	10-17 deg. F.	30-37 deg. F.
Wind direction:	Southeast shifting to the north in the afternoon	North	West shifting to the south in the afternoon
Wind speed:	10-15 mph	around 10 mph	up to 10 mph
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Partly cloudy	Clear	Partly cloudy
Temperatures:	24-30 deg. F.	14-20 deg. F.	29-35 deg. F.
Wind direction:	Southeast shifting to the north in the afternoon	Northwest	West shifting to the southwest in the afternoon
Wind speed:	10-15 mph with gusts to 25 mph	10-15 mph	10-15 mph with gusts to 25 mph
Expected snowfall:	O in.	O in.	O in.