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.

As a weather system passes to the south of the forecast area today, a mix of clouds, sun breaks, and isolated snow showers with less than one inch of accumulation is expected. Areas north of Hwy 50 will see more sun and areas south of Hwy 50 will see more cloud cover. Ridgetop winds have remained moderate in speed out of the NE-E for the past 24 hours and are forecast to continue into this afternoon. Above freezing air temperatures are forecast today for areas below 8,000'.

Observations:

A skier triggered avalanche occurred yesterday in Mini Hall Couloir on Angora Peak (Desolation Wilderness area). The couloir had naturally avalanched on Wednesday during the last storm cycle and had then been skied by 6 to 8 people before the avalanche occurred. The avalanche was triggered from a NE micro terrain feature on a generally W aspect above treeline at 8,350' on a 55 degree slope (firsthand account) (second hand account, photo, videos). This far edge of the couloir had not avalanched with the rest of the couloir on Wednesday. The snowpack failed among exposed rocks with a crown height of 2 to 2.5 feet. The party had observed large faceted snow crystals at this depth while boot packing around rocks nearby. This is believed to have been the failure layer. This is likely the February 19 weak layer that was last associated with human triggered avalanche activity in steep rocky terrain one week ago on March 1. Several other ski descents were made in this area yesterday in similar terrain with no evidence of instability observed by multiple parties. Observations made yesterday on Silver Peak (Pole Creek area) revealed no evidence of instability. Some areas of wet surface snow existed in open areas below 6,500' but ski cuts on 35 degree slopes produced no results. Snowpit data collected above treeline in a rocky area at 8,280' on a N aspect 36 degree slope revealed an overall shallow snowpack with no evidence of instability (pit profile, photo).

Avalanche Concern #1:

Areas of wet surface snow instability are expected to form today on E-SE-S-SW-W aspects. This will mainly occur in areas below 8,000' and north of Hwy 50 where more sun breaks are expected to occur. Human triggered wet loose snow point release type avalanche activity involving the top few inches of the snowpack is the most likely form of instability. Steep convex areas near exposed rocks will be the most likely trigger points.

Avalanche Concern #2:

Very isolated areas of deep slab instability linger above treeline on NW-N-NE aspects in steep rocky terrain. The February 19 weak layer has been linked to 3 human triggered avalanches in the past eight days. This weak layer has a variable composition, but is generally recognized as a hard old snow or thin crust layer 2 to 4 feet deep in the snowpack with a thin layer or graupel or faceted snow crystals above it. All 3 human triggered avalanches occurred above treeline in rocky terrain on NW-N-NE aspects between 8,000' to 8,800' in the southern half of the forecast area. Human triggered avalanche activity on this layer is an unlikely event but yesterday's human triggered avalanche is a reminder of the difference between unlikely and impossible.

The bottom line:

Avalanche danger is LOW with pockets of MODERATE danger due to wet snow instability developing below 8,000' on E-SE-S-SW-W aspects 35 degrees and steeper in response to daytime warming. Very isolated areas of deep slab instability linger above treeline on NW-N-NE aspects in rocky terrain, 40 degrees and steeper.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	19 to 25 deg. F.
Max. temperature in the last 24 hours:	32 to 34 deg. F.
Average wind direction during the last 24 hours:	Northeast to east
Average wind speed during the last 24 hours:	30 mph
Maximum wind gust in the last 24 hours:	59 mph
New snowfall in the last 24 hours:	0 to trace inches
Total snow depth:	87 to 121 inches

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

For 7000-8000 ft:
	Sunday:	Sunday Night:	Monday:
Weather:	Partly cloudy skies with isolated snow showers.	Partly cloudy skies with isolated snow showers in the evening. Mostly cloudy skies after midnight.	Mostly cloudy skies with a chance of snow.
Temperatures:	32 to 39 deg. F.	23 to 29 deg. F.	26 to 34 deg. F.
Wind direction:	NE	SW	SW
Wind speed:	Light winds	Up to 10 mph.	10 to 15 mph with gusts to 25 mph. Winds increasing to 20 to 30 mph with gusts to 45 mph in the afternoon.
Expected snowfall:	0 to trace in.	O in.	Up to 2 in.
For 8000-9000 ft:
	Sunday:	Sunday Night:	Monday:
Weather:	Partly cloudy skies with isolated snow showers.	Partly cloudy skies with isolated snow showers in the evening. Mostly cloudy skies after midnight.	Mostly cloudy skies with a chance of snow.
Temperatures:	27 to 34 deg. F.	18 to 24 deg. F.	20 to 26 deg. F.
Wind direction:	NE	W	SW
Wind speed:	10 to 20 mph with gusts to 30 mph in the morning.	10 to 20 mph with gusts to 30 mph.	10 to 15 mph with gusts to 40 mph. Winds increasing to 30 to 50 mph with gusts to 65 mph in the afternoon.
Expected snowfall:	0 to trace in.	O in.	Up to 2 in.