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.

High pressure is in place over the forecast area, but it will break down tonight and tomorrow. Air temperature inversion will allow for areas above 7,000' to warm into the mid 30s to mid 40s today and tomorrow. Ridgetop winds out of the northeast today will gradually decrease in speed through the day. Winds are forecast to shift to the southwest tonight ahead of an approaching weather system. Southwest winds are expected to become strong to gale force in speed on Wednesday. Accumulating snowfall is expected to hold off until Wednesday night.

Recent Observations:

Observations made yesterday along Frog Lake Ridge (Carson Pass area), Rubicon Peak (West Shore Tahoe area), and in the Deep Creek drainage (Deep Creek area) all revealed pockets of wind slabs in lee areas along and below ridgetops. Stable unconsolidated snow was observed in wind protected areas below treeline. Wind slabs showed skier triggered cracking in most recently wind loaded areas on W-NW aspects. Recent NE winds have scoured many N-NE-E aspects in near and above treeline terrain. Snowpit data collected along Frog Lake Ridge at the site of the snowboarder and skier triggered avalanches on Jan 5th revealed an increase in snowpack stability on the older NE aspect wind slabs that failed in those avalanches. Snowpit data collected on the NW ridge of Rubicon Peak indicated that unstable wind slabs lingered in recently wind loaded areas on W-NW aspects (pit profiles, photos, videos, more info).

Avalanche Problem #1: Wind Slabs

Ridgetop winds out of the NE over the past several days built pockets of wind slabs in lee areas mainly along and directly below ridgelines. The size of these wind slabs varies greatly with terrain and location. Slab thickness ranges from just a few inches to over a foot thick. Recently wind loaded areas on SW-W-NW aspects are the most suspect, but wind slabs may exist on other aspects in complex terrain.

Significantly higher snowfall amounts (6-12") on Sunday at the far southern end of the forecast area keep concerns ongoing for locally greater snowpack instability both above and below treeline for areas near the Sierra Crest from Hwy 88 southward, especially in the Ebbetts Pass area.

The bottom line:

Near and above treeline, avalanche danger is LOW with pockets of MODERATE danger on SW-W-NW aspects on slopes 35 degrees and steeper due to recently formed wind slabs. Below treeline, generally LOW avalanche danger exists. Isolated areas of snowpack instability may exist below treeline near the Sierra Crest from Hwy 88 southward.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	26 to 35 deg. F.
Max. temperature in the last 24 hours:	32 to 40 deg. F.
Average wind direction during the last 24 hours:	Northeast
Average wind speed during the last 24 hours:	25 mph
Maximum wind gust in the last 24 hours:	42 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	62 to 86 inches

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

For 7000-8000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Partly cloudy skies.	Partly cloudy skies.	Mostly cloudy skies with a chance of snow showers in the afternoon west of Hwy 89.
Temperatures:	37 to 43 deg. F.	26 to 32 deg. F.	35 to 42 deg. F.
Wind direction:	E	SW after midnight.	SW
Wind speed:	10 to 15 mph. Gusts up to 25 mph in the morning.	Light winds increasing to 15 to 20 mph with gusts to 30 mph after midnight.	25 to 30 mph with gusts to 50 mph, increasing to 35 to 40 mph with gusts to 60 mph in the afternoon.
Expected snowfall:	O in.	O in.	0 to trace in.
For 8000-9000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Partly cloudy skies.	Partly cloudy skies.	Mostly cloudy skies with a chance of snow showers in the afternoon west of Hwy 89.
Temperatures:	34 to 41 deg. F.	23 to 30 deg. F.	35 to 41 deg. F.
Wind direction:	NE	SW	SW
Wind speed:	15 to 20 mph with gusts to 40 mph. Gusts decreasing to 30 mph in the afternoon.	10 to 15 mph with gusts to 25 mph, increasing to 25 to 30 mph with gusts to 45 mph after midnight.	40 to 45 mph with gusts to 70 mph, increasing to 55 to 60 mph with gusts to 90 mph in the afternoon.
Expected snowfall:	O in.	O in.	0 to trace in.