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 well advertised and very cold storm system is on track to impact the forecast area today. For most of today, increasing clouds, increasing winds, and snow showers will occur before high intensity snowfall begins during the late afternoon and evening hours. Ridgetop winds are increasing in speed this morning ahead of the approaching storm. Winds will remain out of the southwest today, becoming strong to gale force in speed by this afternoon. Maximum daytime air temperatures above 7,000' are only expected to warm into the upper teens and low 20s today. Once high intensity snowfall begins late today, it is expected to continue overnight and through the day on Friday.

Observations:

Recent observations from around the forecast area indicate areas of ongoing instability caused by a mix of lingering upside down storm snow instability created last week and wind slab formation from ongoing wind transport of recent storm snow over this past week. No new avalanche activity has been reported since Monday, when large human triggered avalanches occurred in the Donner Summit and Carson Pass areas (click here for more info). Over the past two days, ongoing evidence of instability has been noted near and above treeline in wind loaded areas on N-NE-E aspects in the form of blowing snow, shooting cracks, and stability tests indicating that slope scale failure of wind slabs remains possible. No ongoing evidence of instability has been noted below treeline or in non wind loaded areas.

Primary Avalanche Concern: Wind Slabs

For most of today, avalanche concerns will remain focused on winds slabs that exist in wind loaded areas, mainly near and above treeline on N-NE-E aspects. Off and on periods of blowing snow over this past week has kept this instability ongoing. Increasing ridgetop winds today combined with plenty of snow still available for wind transport will continue to fuel this avalanche concern today. In many areas these wind slabs have taken on hard slab characteristics which will allow a person to get further put onto the slab before failure occurs or for more than one person to travel the slope before an avalanche occurs. Large human triggered avalanches with snowpack failure several feet deep remain possible today.

Secondary Avalanche Concern: Storm snow

By late today, areas of storm snow instability are expected to form as new snow accumulates. Areas of instability are expected to form first in near and above treeline wind loaded areas on N-NE-E aspects before spreading to cross loaded NW and SE aspects and then to below treeline areas. During the afternoon hours, small human triggered avalanches involving the new snow will be possible in wind loaded areas. By sunset, larger human triggered avalanches and isolated natural avalanches may become possible in the most heavily wind loaded terrain near and above treeline.

The bottom line:

Near and above treeline, avalanche danger is MODERATE on N-NE-E aspects, 35 degrees and steeper. Pockets of MODERATE danger exist on NW and SE aspects, 35 degrees and steeper. Below treeline, avalanche danger remains LOW for all elevations and aspects. Human triggered avalanches ranging from small to large in size are possible today. A significant increase in avalanche danger is expected to occur this evening, continuing overnight and through the day on Friday. Areas of CONSIDERABLE avalanche danger may form prior to sunset today in wind loaded areas with human triggered avalanches becoming likely and 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:	12 to 17 deg. F.
Max. temperature in the last 24 hours:	21 to 32 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	35 mph
Maximum wind gust in the last 24 hours:	85 mph
New snowfall in the last 24 hours:	0 to trace inches
Total snow depth:	85 to 117 inches

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

For 7000-8000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Cloudy skies with a chance of snow showers in the morning. Snow in the afternoon.	Cloudy skies with high intensity snowfall.	Cloudy skies with high intensity snowfall.
Temperatures:	17 to 24 deg. F.	10 to 17 deg. F.	13 to 20 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	20 to 30 with gusts to 50 mph.	25 to 40 mph with gusts to 70 mph.	20 to 35 mph with gusts to 70 mph. Gusts decreasing to 45 mph in the aftenoon.
Expected snowfall:	Up to 2 in.	10 to 18 in.	10 to 18 in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Cloudy skies with a chance of snow showers in the morning. Snow in the afternoon.	Cloudy skies with high intensity snowfall.	Cloudy skies with high intensity snowfall.
Temperatures:	16 to 22 deg. F.	10 to 16 deg. F.	11 to 17 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	45 to 60 mph with gusts to 75 mph. Winds increasing to 55 to 70 mph with gusts to 90 mph in the afternoon.	55 to 75 mph with gusts to 95 mph.	45 to 60 mph with gusts to 90 mph. Winds decreasing to 35 to 50 mph with gusts to 60 mph in the afternoon.
Expected snowfall:	Up to 3 in.	10 to 18 in.	12 to 18 in.