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.

Increasing cloud cover and increasing winds are expected today as the next storm system approaches the forecast area. Remote sensors are reporting air temperatures above 7,000' this morning in the upper teens to mid 20s. Maximum daytime air temperatures today are forecast to reach the upper 20s to mid 40s as warm air moves into the region ahead of the approaching storm. Ridgetop winds remain out of the southwest this morning and are moderate in speed. Wind speed is expected to increase to strong today and become gale force overnight. New snow amounts of 6 to 12 inches above 7,000' are expected tonight with an additional 4 to 8 inches for tomorrow.

Recent Observations:

Yesterday on Steven's Peak (Carson Pass area) a party reported that a ski cut placed in a wind loaded gully under the summit rocks (around 9.700', NE aspect, above treeline terrain) produced an avalanche with a 12 to 18 inch crown that was approximately 50' wide and traveled 300' down slope (more info). Observers in the Mount Rose region also reported several shallow skier triggered avalanches in response to ski cuts in wind loaded near treeline terrain at 9,400' on a NE aspect, with a 45 degree slope angle. Theses avalanches typically propagated 50-70' ahead of the skier with slabs 4-6" deep, failing within the recent storm snow from the past two days. Observations made yesterday in Candy Land (Outside Bear Valley Ski Area boundary) revealed that on near and below treeline N aspects in this area around 7,900', the persistent weak layer of old crust and faceted snow exists 4' to 5' below the snow surface. Snowpit tests indicated that if collapse of this layer could be triggered, propagation along the layer remains likely to occur (pit profile, more info).

Today's Primary Avalanche Concern: Wind Slabs

Unstable wind slabs that existed yesterday in near and above treeline areas may linger today as increasing winds take any remaining snow available for wind transport and further wind load areas on NW-N-NE-E-SE aspects. In areas south of Hwy 50, up to 7 inches of recent storm snow remains available for wind transport today. Avalanche activity involving recently formed surface wind slabs is expected to remain limited to the top 6 inches to 2 feet of the snowpack.

Today's Secondary Avalanche Concern: Persistent Deep Slabs

The persistent weak layer of old crust and faceted snow still exists above and below treeline on most NW-N-NE aspects. Since March 17th, 15 out of the 18 field observations targeting this weak layer indicate that collapse of this weak layer is still likely to cause propagating slab failure deep within the snowpack. Transmitting sufficient force through the snowpack to trigger a deep slab avalanche remains very difficult due to the depth of the weak layer and the strength of the overlying slab in most areas. Isolated areas with a comparatively shallow snowpack where this weak layer is less than 4 feet below the snow surface such as near exposed rock outcrops, cliffs, unsupported slopes, and other complex terrain features are the most likely areas to trigger failure of this weak layer. Large triggers such as cornice collapse or other avalanches could provide sufficient force to trigger a deep slab avalanche. Any deep slab avalanches that occur at this time will be large and destructive.

The bottom line:

Isolate pockets of MODERATE avalanche danger exist both above and below treeline on NW-N-NE aspects and near and above treeline E-SE aspects on slopes 35 degrees and steeper due to ongoing persistent deep slab instability and recently formed surface wind slabs. Large destructive deep slab avalanches remain possible in isolated areas. For all other areas, avalanche danger is generally LOW.

Avalanche danger is will increase tonight for all areas 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:	19 to 24 deg. F.
Max. temperature in the last 24 hours:	22 to 30 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	38 mph
Maximum wind gust in the last 24 hours:	59 mph
New snowfall in the last 24 hours:	Trace to 1 inches
Total snow depth:	42 to 77 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 scattered snow showers in the afternoon.	Cloudy skies with snow.	Cloudy skies with snow in the morning. Snow showers in the afternoon.
Temperatures:	35 to 44 deg. F.	22 to 29 deg. F.	37 to 43 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	25 to 35 mph with gusts to 55 mph.	35 to 45 mph with gusts to 60 mph.	25 to 30 mph with gusts to 50 mph.
Expected snowfall:	Up to 1 in.	6 to 10 in.	4 to 8 in.
For 8000-9000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Cloudy skies with scattered snow showers in the afternoon.	Cloudy skies with snow.	Cloudy skies with snow in the morning. Snow showers in the afternoon.
Temperatures:	28 to 36 deg. F.	23 to 29 deg. F.	31 to 41 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	40 to 60 mph with gusts to 75 mph. Gusts increasing to 90 mph in the afternoon.	55 to 60 mph increasing to 65 to 75 mph after midnight. Gusts to 105 mph.	60 to 65 mph with gusts to 90 mph, decreasing to 45 to 50 mph with gusts to 75 mph in the afternoon.
Expected snowfall:	Up to 1 in.	6 to 12 in.	4 to 8 in.