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.

Sunny and slightly warmer weather should continue today due to the high pressure ridge over the forecast area. Daytime highs should reach into the low to mid 30's above 7000 ft. Tonight the forecast calls for the winds to shift to the southwest and increase ahead of a cold low pressure system. Cloud cover should also start to increase tonight as this system approaches. The main portion of the low pressure system should reach the Tahoe area by mid to late morning tomorrow bringing even more clouds, wind, and a chance of snow. The forecast calls for a 30-40% chance of snow during the day tomorrow with accumulations around an inch possible along the Sierra Crest. This system will also bring daytime highs back down into the low to mid 20's for tomorrow.

Observations:

Observations on Elephant's Back yesterday showed a very shallow snowpack with lots of anchors extending through the snow where snow existed. In many areas around Carson Pass, the NE-E winds had scoured exposed slopes back to bare ground. In the shallow areas where snow remained, faceting continues to weaken most of the snowpack. On some of the more exposed but not completely scoured slopes, patches of 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 even though starting a fracture below the hard slab is difficult, once the facets break fractures can travel through them. In this area the strength of the hard slab and the anchors poking through the snowpack currently hold the snowpack together. 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:

LOW avalanche danger exists on all elevations and at all aspects. Use normal 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:	18-20 deg. F.
Max. temperature in the last 24 hours:	28-34 deg. F.
Average wind direction during the last 24 hours:	Variable between S and ENE
Average wind speed during the last 24 hours:	5-10 mph
Maximum wind gust in the last 24 hours:	23 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:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Sunny	Partly cloudy	Cloudy with a 30-40% chance of snow.
Temperatures:	30-37 deg. F.	14-21 deg. F.	22-29 deg. F.
Wind direction:	West shifting to the southwest in the afternoon	Southwest	West
Wind speed:	up to 10 mph	10-15 mph with gusts to 25 mph after midnight	10-15 mph with gusts to 30 mph
Expected snowfall:	O in.	O in.	up to 1 in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Sunny	Partly cloudy	Cloudy with a 30-40% chance of snow
Temperatures:	29-35 deg. F.	13-20 deg. F.	20-26 deg. F.
Wind direction:	West shifting to the southwest in the afternoon	Southwest	West
Wind speed:	10-15 mph with gusts to 25 mph	10-20 mph with gusts to 40 mph	20-30 mph with gusts to 50 mph in the afternoon
Expected snowfall:	O in.	O in.	up to 1 in.