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.

A significant storm system will move into the forecast area today. An increase in clouds, winds and snow showers will occur throughout the day. Calm winds for most of yesterday increased in speed overnight and are moderate in speed out of the west this morning. Air temperatures at 8,500' are in the mid to upper 20s this morning with a few degrees of daytime warming expected. High intensity snowfall is expected to begin late this afternoon or this evening. New snow amounts of 1 to 1.5 feet are expected over the next 24 hours. Ridgetop winds are forecast to increase to gale force overnight.

Observations:

Observations made yesterday on Jake's Peak (West Shore Tahoe area) revealed wind slabs above and below treeline. Snowpit data obtained just below the south summit on a NE aspect at 9,130' showed a high density wind slab over lower density snow that retained lingering fracture propagation potential (video, pit profile, more info). On Ralston Peak (Echo Summit area) and on Tamarack Peak (Mount Rose area) widespread stable wind slabs were noted with no signs of instability in response to human triggered cornice collapse or the weight of a skier on a slope. Snowpit data obtained in both areas revealed no further significant evidence of instability (photos, more info). Evidence of  natural avalanches that occurred on wind loaded NE-E aspects during the period of gale force winds and snowfall Saturday night into Sunday morning were noted in the Desolation Wilderness and Donner Summit areas (photos, more info).

Avalanche concern #1: Storm snow

During the late afternoon and evening hours, sufficient new snowfall is expected to allow new soft slabs of storm snow to form in wind loaded areas. Small human triggered avalanches will become increasingly possible this afternoon and evening, especially during the few hours prior to sunset. Areas of instability are expected to form first in near and above treeline terrain on N-NE-E aspects. Instability will then spread to adjacent aspects and below treeline areas during the overnight hours with natural avalanche activity possible.

Avalanche concern #2: Wind Slabs

The period of gale force winds and snowfall over the past weekend produced widespread wind slabs. In vast majority of areas these slabs are now stable. However, lingering pockets of instability may exist in very isolated areas. Complex terrain on cold shady N-NE aspects is the most suspect. Evidence of snowpack instability in these areas is not obvious. Careful and diligent slope evaluation is required to detect isolated pockets of instability. Any wind slab avalanche activity that occurs today is expected to be human triggered and occur within the top 1 foot of the snowpack.

The bottom line:

For most of today, avalanche danger is LOW for all elevations and aspects. During the afternoon and evening hours, pockets of MODERATE danger are expected to form near and above treeline on N-NE-E aspects, 35 degrees and steeper. Avalanche danger will increase during the overnight hours with natural avalanches possible.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	26 to 30 deg. F.
Max. temperature in the last 24 hours:	26 to 39 deg. F.
Average wind direction during the last 24 hours:	West
Average wind speed during the last 24 hours:	Prior to 6pm 5 mph, after 6pm 35 mph
Maximum wind gust in the last 24 hours:	48 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	62 to 92 inches

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

For 7000-8000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Cloudy skies with a chance of snow showers in the morning. Numerous snow showers in the afternoon.	Cloudy skies with high intensity snowfall.	Cloudy skies with high intensity snowfall in the morning. Snow showers in the afternoon.
Temperatures:	27 to 34 deg. F.	19 to 26 deg. F.	19 to 26 deg. F.
Wind direction:	W	SW	SW
Wind speed:	10 to 15 mph with gusts to 25 mph in the afternoon.	15 to 25 mph with gusts to 50 mph. Winds increasing to 25 to 40 mph with gusts to 70 mph after midnight.	20 to 35 mph with gusts to 75 mph. Gusts decreasing to 55 mph in the afternoon.
Expected snowfall:	1 to 3 in.	10 to 16 in.	6 to 12 in.
For 8000-9000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Cloudy skies with a chance of snow showers in the morning. Numerous snow showers in the afternoon.	Cloudy skies with high intensity snowfall.	Cloudy skies with high intensity snowfall in the morning. Snow showers in the afternoon.
Temperatures:	23 to 30 deg. F.	16 to 23 deg. F.	16 to 23 deg. F.
Wind direction:	W	SW	SW
Wind speed:	10 to 20 mph with gusts to 30 mph. Gusts in creasing to 40 mph in the afternoon.	30 to 40 mph with gusts to 85 mph. Winds increasing to 45 to 60 mph with gusts to 120 mph after midnight.	35 to 50 mph with gusts to 100 mph. Gusts decreasing to 80 mph in the afternoon.
Expected snowfall:	1 to 3 in.	12 to 18 in.	6 to 12 in.