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 last in this series of storms is passing through the forecast area and will exit the region by this afternoon. An additional 12 to 21 inches of new snow has accumulated over the past 24 hours with 8 to 17 inches of that during the past 12 hours. The greatest overnight accumulations were observed in the far southern portion of the forecast area. Storm totals for the past three days are running 47 to 90 inches. Ridgetop winds remain out of the southwest this morning. Winds speeds decreased to moderate in speed for much of the day yesterday before increasing to strong in speed last night. Wind speeds are on the decrease this morning and are forecast to become moderate in speed today before becoming light to moderate tomorrow. After an ongoing period of high intensity snowfall early this morning, snowfall is expected to decrease to snow shower activity this afternoon. An additional 2 to 6 inches of new snow is expected to accumulate during the day today. Air temperatures in the mid teens to upper 20s today will plummet tonight down into the single digits as snow shower activity further decreases and partial sky clearing occurs.

Observations:

Observations made yesterday on Jake's Peak (West Shore Tahoe area) revealed continued instability within the storm snow and isolated slab avalanche activity below treeline. Below 7,900' no evidence of instability was observed on the very wind protected N-NE-E aspect below treeline areas. Above 8,000', slight wind effects and slight surface slab formation became noticeable on NE-E aspects. Within the storm snow a thin layer of rimed snow crystals was observed 15 inches below the snow surface (now likely 24 to 30 inches below the surface) that produced cracking and failure of the very soft slab above while trail breaking. Snowpit data collected in this area on a NE aspect 38 degree slope at 8,080' revealed very repeatable test results indicating likely slab fracture on this layer (pit profile, photo, video, more info). A bit higher at 8,300' evidence of a small slab avalanche was observed in a steep N aspect gully with trigger unknown. The avalanche crown, flanks, and debris had been covered with new snow indicating that the avalanche had occurred either on Thursday afternoon or very early Friday morning. The crown appeared completely filled in by new snow, but the flank height matched well with the depth of the rimed crystal weak layer observed in the immediate area (photo, more info). No backcountry observations were made or received from above treeline terrain yesterday due to ongoing poor visibility and difficult access.

Primary Avalanche Concern: Wind Slabs

Unstable slabs of wind loaded storm snow in lee areas remain the main concern for large destructive avalanches near and above treeline on NW-N-NE-E-SE aspects. Once avalanches initiate, there is a possibility that the failure layer may step down to deeper layers within the storm snow causing large and destructive slab avalanches. The possibility of natural avalanches will continue this morning before decreasing this afternoon. Large human triggered avalanches will remain likely all day long.

Avalanche Concern #2: Storm Snow Instabilities

Observations made over the past two days have revealed ongoing instabilities within the storm snow. Slab failure was noted both days in areas with minimal wind effect. Some of this same instability may still exist today. The additional 8 to 17 inches of new snow last night will likely have additional storm snow instabilities on top of those already observed. Slab avalanche activity remains possible today in steep areas below treeline, especially in response to human triggers. In very wind protected areas, loose snow avalanches may occur in steep areas where the overlying slab is too soft to sustain long fractures.

The bottom line:

Near and above treeline, avalanche danger is MODERATE with pockets of CONSIDERABLE danger on NW-N-NE-E-SE aspects, 35 degrees and steeper. Below treeline, avalanche danger is MODERATE on all aspects, 35 degrees and steeper. Large destructive avalanches are possible.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	16 to 19 deg. F.
Max. temperature in the last 24 hours:	24 to 27 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	32 mph
Maximum wind gust in the last 24 hours:	91 mph
New snowfall in the last 24 hours:	12 to 21 inches
Total snow depth:	96 to 135 inches

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

For 7000-8000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Cloudy to mostly cloudy skies with snow showers decreasing in the afternoon.	Mostly cloudy skies with scatted snow showers in the evening. Isolated snow showers after midnight.	Mostly cloudy skies with scattered snow showers.
Temperatures:	17 to 27 deg. F.	0 to 10 deg. F.	19 to 26 deg. F.
Wind direction:	SW	SW shifting to W	W
Wind speed:	10 to 20 mph with gusts to 30 mph. Gusts increasing to 40 mph in the afternoon.	10 to 15 mph with gusts to 40 mph decreasing to around 10 mph with gusts to 25 mph after midnight.	Around 10 mph with gusts to 25 mph.
Expected snowfall:	2 to 6 in.	Trace to 1 in.	Trace to 1 in.
For 8000-9000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Cloudy to mostly cloudy skies with snow showers decreasing in the afternoon.	Mostly cloudy skies with scattered snow showers.	Mostly cloudy skies with scattered snow showers.
Temperatures:	14 to 21 deg. F.	-1 to 9 deg. F.	12 to 22 deg. F.
Wind direction:	SW	SW shifting to W	W
Wind speed:	20 to 30 mph with gusts to 45 mph.	15 to 25 mph with gusts to 40 mph decreasing to 10 to 15 mph with gusts to 30 mph after midnight.	10 to 20 mph with gusts to 30 mph.
Expected snowfall:	2 to 6 in.	Trace to 1 in.	Trace to 1 in.