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.

The north-northeast winds have started to shift more to the east along the Sierra Crest this morning. They should remain strong through midday with gusts up to 90 mph along the crest. By this afternoon they should begin to decrease. Later in the day tomorrow, the winds could pick back up as another low pressure moves past the forecast area. The northeasterly flow associated with these winds should keep temperatures cool today and tonight with only slight warming expected during the day tomorrow.

Observations:

Yesterday, closer observations of many of the avalanche starting zones in the Mt Rose area revealed that the strong NE winds have successfully removed the Nov 18th facet layer along with all of the other snow on these slopes. Exposed rocks now cover 90% of the Hourglass where almost 2 ft of snow existed before this wind event (photo). Even in starting zones below treeline less exposed to the NE winds, enough scouring has taken place to remove most of the snow (photo from the backside of the Fireplug). Below treeline in more wind-protected areas, a shallow snowpack with several anchors poking through the snowpack exists. In these protected areas, the Nov 18th facets still exist and still remain weak (photo). However, observations indicated that the plethora of anchors poking through this layer prevents fractures caused when the facets break from traveling very far. The snow surface varied from a discontinuous hard wind slab to shallow unconsolidated snow in these below treeline areas (more info).

Avalanche Concern #1: Persistent slabs

The areas where avalanche activity remains possible and the areas where recreating on snow remains possible continue to shrink. The strong NE winds have removed the persistent weak layer (Nov 18th facets) from many open N-NE-E facing slopes. In other areas where the Nov. 18th facets remain, the snow on top of them has weakened to the point that it is no longer a slab, or such a shallow snowpack exists that anchors poking through the snow disrupt the weak layer. In these areas fractures in the weak layer should not propagate enough to cause avalanche activity. Isolated pockets of terrain may still exist with slabs on top of the weak Nov. 18th facets. Unfortunately the terrain most likely to hold these pockets of instability matches the terrain that holds the best recreation potential. The N-NE-E aspects above 8000 ft. that hold the most snow represent the areas where the thickest and weakest facets exist under the largest slabs.

The bottom line:

On NW-N-NE-E aspects above 8,000', isolated pockets of MODERATE avalanche danger may remain on slopes steeper than 35 degrees both above and below treeline. LOW avalanche danger exists in all other areas.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	8-10 deg. F.
Max. temperature in the last 24 hours:	29-34 deg. F.
Average wind direction during the last 24 hours:	Northeast shifting to the East northeast
Average wind speed during the last 24 hours:	40-45 mph
Maximum wind gust in the last 24 hours:	86 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:
	Saturday:	Saturday Night:	Sunday:
Weather:	Sunny	Clear	Sunny
Temperatures:	23-28 deg. F.	20-25 deg. F.	33-38 deg. F.
Wind direction:	East	East	East
Wind speed:	15-30 mph with gusts to 55 mph decreasing to 10-20 mph with gusts to 40 mph in the afternoon	10-20 mph with gusts to 35 mph	10-20 mph
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Sunny	Clear	Sunny
Temperatures:	22-27 deg. F.	18-23 deg. F.	28-33 deg. F.
Wind direction:	East	East	East
Wind speed:	30-45 mph with gusts to 90 mph decreasing to 20-35 mph with gusts to 65 mph in the afternoon	15-30 mph with gusts to 60 mph	15-25 mph with gusts to 55 mph
Expected snowfall:	O in.	O in.	O in.