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.

The first and second waves of the current storm cycle passed through the forecast area yesterday and last night. A third wave will pass through the area this morning. Yesterday's first wave brought snow level up to 7,000' to 7,500' and deposited around 3 to 7 inches of snow at the upper elevations. The second wave last night brought snow level down to 5,000' to 5,500' and deposited another 5 to 9 inches of new snow. The third wave forecast for today is expected to maintain snow levels at 5,000 to 5,500' and deposit an additional 1 to 4 inches of new snow with the greatest accumulations south of Lake Tahoe. The focus of the greatest accumulations have shifted around the forecast area during the first and second waves with total accumulations of 8 to 12 inches across the region thus far. Ridgetop winds were strong yesterday out of the southwest. Winds will remain out of the southwest today and decrease to moderate in speed. Snow shower activity is expected to continue through this morning before sun breaks occur this afternoon. Light winds tonight and sunny skies are forecast for tomorrow.

Observations:

Observations made yesterday showed significant wind loading mainly near and above treeline, with pockets of wind loading below treeline. The greatest evidence of instability was observed on Mt. Judah's Wildflower Ridge (Donner Summit area). This below treeline/near treeline E aspect area at 7,680' that traditionally receives very heavy wind loading produced test slope failure of slabs of wind loaded storm snow up to 2 feet deep in response to the weight of a skier on the slope (photo, video, more info). On Hidden Peak (West Shore Tahoe area) wind loading was limited to near and above treeline areas with nonreactive slabs up to 8 inches deep forming at mid day in wind loaded areas on NE-E aspects along the summit ridge at 9,130'. Good bonding of the new snow to the old snow surface was noted in all areas above snow level (pit profile, photo, video, more info). On the Far east ridge of Tamarack Peak (Mount Rose area) conditions similar to Hidden Peak were noted with nonreactive slabs up to 6 inches deep having formed in wind loaded areas on N-NE aspects near treeline at 9,280' at mid day. Skier triggered cracking was limited to very, very small slab failures in wind loaded areas near and above treeline (photos, videos, more info).

Avalanche Concern #1: Storm snow

With additional snowfall and winds last night doubling the amount of new snow that was observed in most areas yesterday, ongoing storm snow instabilities are expected today. Wind loaded areas both above and below treeline will hold the greatest instability with slabs 1 to 3 feet deep expected. Snowpack failure is expected to occur at or above the old/new snow interface. Ongoing winds through this evening will keep some amount of wind loading ongoing. Natural avalanches will remain possible in isolated areas today. Human triggered avalanches are expected.

Avalanche Concern #2: Warming instability

As breaks in cloud cover occur this afternoon, near to above freezing air temperatures below 9,000' combined with March levels of solar radiation will cause some amount of warming instability. Cloud cover forecasts are notoriously difficult and sun breaks may be highly localized. In areas where significant solar radiation is directed on SE-S-SW aspects warming instability and a rapid increase in snowpack instability will occur. Cross loaded S-SE aspect gullies and other recently wind loaded southerly aspects will hold the greatest opportunity for slab avalanches to occur under the influence of warming.

The bottom line:

Near and above treeline avalanche danger is MODERATE with pockets of CONSIDERABLE danger on N-NE-E aspects on slopes 35 degrees and steeper. Below treeline avalanche danger is MODERATE on all aspects on slopes 35 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:	22 to 26 deg. F.
Max. temperature in the last 24 hours:	28 to 34 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	52 mph
Maximum wind gust in the last 24 hours:	78 mph
New snowfall in the last 24 hours:	8 to 12 inches
Total snow depth:	94 to 138 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 snow showers diminishing by this afternoon with partial clearing.	A slight chance of snow showers in the early evening, becoming partly cloudy.	Sunny skies in the morning with increasing thin high clouds in the afternoon.
Temperatures:	29 to 36 deg. F.	19 to 25 deg. F.	35 to 40 deg. F.
Wind direction:	SW	SW becoming variable	E shifting to W late in the day.
Wind speed:	10 to 20 mph with gusts to 35 mph.	10 to 15 mph decreasing to up to 10 mph after midnight.	Up to 10 mph.
Expected snowfall:	Up to 2 inches with local accumulations south of Lake Tahoe up to 4 in.	0 to trace in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Cloudy skies with snow showers diminishing by this afternoon with partial clearing.	A slight chance of snow showers in the early evening, becoming partly cloudy.	Sunny skies in the morning with increasing thin high clouds in the afternoon.
Temperatures:	22 to 29 deg. F.	15 to 22 deg. F.	26 to 35 deg. F.
Wind direction:	SW	W shifting to N	NE shifting to SW.
Wind speed:	25 to 35 mph with gusts to 50 mph.	15 to 25 mph with gusts to 45 mph. Winds shifting and decreasing to 10 to 15 mph after midnight.	10 to 15 mph shifting and increasing to 10 to 20 mph with gusts to 30 mph in the afternoon.
Expected snowfall:	Up to 2 inches with local accumulations south of Lake Tahoe up to 4 in.	0 to trace in.	O in.