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.

Another day of sun, light winds, and warm air temperatures at the upper elevations will occur today. The pattern will begin to change on Sunday ahead of an approaching weather system forecast to bring snowfall back to the forecast area Monday and Tuesday. An air temperature inversion is once again in place this morning with many remote sensors above 7,000' reporting air temperatures in the upper 30s and low 40s. Ridgetop winds shifted to the NE yesterday and remained light to moderate through the day. Light E winds are expected this morning before shifting to SW and remaining light this afternoon.

Yesterday, observations made below treeline on Mt. Lola in the Independence Lake area at 8,650' on a N aspect 30 degree slope continue to point to persistent instability of the Oct 19 facet layer near the bottom of the snowpack (video). This was also observed on Castle Peak in the Donner Summit area near treeline at 8,500' on a N aspect 31 degree slope (video). Fracture propagation tests indicated that fracture propagation and snowpack failure along this layer remains likely once triggered. This matches well with observations made Wednesday and Thursday in the Mount Rose and Luther Pass areas. Observations made Thursday below treeline on Silver Peak in the Pole Creek area at 8,020' on a NE aspect, 30 degree slope indicated that in areas where the Oct 19 facet layer was less developed, the snowpack was now stable despite evidence of instability prior to the Dec 12 - Dec 13 storm cycle. Additional observations made yesterday on Mt. Lola on a below treeline road cut at 7,140' on N aspect 26 degree slope further supported that stabilization of the basal facet layer was occurring in some areas.

Today's avalanche concerns continue to focus on persistent deep slab instability below treeline. Areas above 8,000' on NW-N-NE aspects that are somewhat protected from NE winds hold the Oct 19 facet layer near or at the bottom of the snowpack. In some locations, these faceted crystals have rounded and bonded with the slab above stabilizing the snowpack. There are two potentially unstable snowpack structures that are worrisome at this time. The first exists between 8,000' to 8,600' where the faceted weak layer at ground level is very well developed (soft and sugary). The second exists above 8,600' where the facet layer sits on top of the ice mass that formed in early Oct. Both of these configurations continue to show evidence of instability. Human triggered failure of this weak layer is becoming increasing difficult. However, the right trigger placed in a shallow portion of the snowpack, near an isolated rock, or isolated tree could still create an avalanche with the dense overlying slab 2 to 4+ feet in thickness. An avalanche of this type holds significant destructive potential and severe consequences for anyone caught in the avalanche. Dig your pits and choose your slopes wisely as this layer is very weak in some locations and nonexistent in others.

The bottom line:

Near treeline and below treeline, pockets of MODERATE avalanche danger exist above 8,000' on NW-N-NE aspects, 35 degrees and steeper due to persistent deep slab instability. Above treeline and for all other areas, avalanche danger is LOW.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	35 to 41 deg. F.
Max. temperature in the last 24 hours:	38 to 51 deg. F.
Average wind direction during the last 24 hours:	NE
Average wind speed during the last 24 hours:	20 mph
Maximum wind gust in the last 24 hours:	40 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	36 to 53 inches

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

For 7000-8000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Partly cloudy skies.	Partly cloudy skies.	Mostly cloudy skies.
Temperatures:	40 to 47 deg. F.	22 to 29 deg. F.	39 to 46 deg. F.
Wind direction:	E shifting to SW	SW	SW
Wind speed:	Light winds	Up to 10 mph after midnight.	10 to 20 mph with gusts to 25 mph. Gusts increasing to 40 mph in the afternoon.
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Partly cloudy skies.	Partly cloudy skies.	Mostly cloudy skies.
Temperatures:	43 to 49 deg. F.	22 to 29 deg. F.	37 to 44 deg. F.
Wind direction:	E shifting to SW	SW	SW
Wind speed:	Light winds up to 10 mph in the afternoon.	10 to 15 mph with gusts up to 25 mph after midnight.	20 to 30 mph with gusts to 35 mph. Gusts increasing to 50 mph in the afternoon.
Expected snowfall:	O in.	O in.	O in.