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 low pressure system that brought snow to the forecast area yesterday is moving off to the east. The region will remain under cloudy skies with periods of snow showers expected through Friday. New snow amounts from the past 24 hours range from 2 to 8 inches. Total snowfall amounts from this storm cycle measure 9 to 12 inches with little variation across the forecast area. Ridgetop winds that were gale force out of the southwest for much of yesterday decreased to light in speed last night. Winds are forecast to shift to the E to SE today and remain light in speed. Air temperatures in the teens and 20s across the forecast area this morning will warm into the 20s today for most areas above 7,000'.

Recent Observations:

Observations made yesterday on Andesite Ridge (Donner Summit area), Silver Peak (Pole Creek area), and along Frog Lake Ridge (Carson Pass area) all revealed unstable snowpack conditions. Wind slabs and storm slabs existed on top of a thin 0.5 to 1 inch thick layer of lower density snow at the old/new snow interface in all areas. Intentional skier triggered slab avalanches occurred on test slopes in each of these areas yesterday on N-NE aspects both above and below treeline (videos, photos, pit profiles, more info).

Along Frog Lake Ridge, two very small natural avalanches were noted in above treeline terrain on a NE aspect around 8,700'. These two avalanches appeared to have occurred early in the storm cycle. On Andesite Ridge, Silver Peak, and Frog Lake Ridge, skier triggered shooting cracks were widespread in wind loaded areas. On Silver Peak widespread collapsing and whumphing was also noted in the 7,000' to 8,000' elevation range.

On Silver Peak in the 7,000' to 8,000' range this lower density layer was composed of early stage faceted snow crystals on top of the thin rain crust that formed out of the March 3rd rain/snow event. On Andesite Ridge and along Frog Lake Ridge, this low density weak layer was composed of storm snow on top of a thin melt-freeze crust that formed in the warm days leading up to this storm cycle.

Avalanche Problem #1: Wind Slabs

Strong to gale force ridgetop winds blew out of the SW for much of the day yesterday. Unstable wind slabs that existed yesterday are expected to linger today with the ongoing possibility of human triggered avalanches. These wind slabs are largest and most well developed near and above treeline on N-NE-E aspects. Winds slabs also exist on cross loaded NW and SE aspects in similar terrain. Wind slabs up to 2 feet deep were observed yesterday in many wind loaded areas.

Avalanche Problem #2: Storm Slabs

In below treeline areas with little to no wind effect, storm slabs that sit on top of a thin weak layer of low density snow at the old/new snow interface are expected to remain unstable today.  Human triggered avalanches remain possible today in below treeline wind protected areas. Slabs will range from 6 to 12 inches in depth and may be found in wind protected areas on any aspect. Slopes steeper than 35 to 37 degrees may be required for avalanche activity to occur.

The bottom line:

Near and above treeline, areas of MODERATE avalanche danger exist on all aspects on slopes steeper than 35 degrees due to recently formed wind slabs. Below treeline, pockets of MODERATE avalanche danger exist on all aspects on slopes steeper than 35 degrees due to recently formed storm slabs.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	17 to 23 deg. F.
Max. temperature in the last 24 hours:	17 to 24 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	21 mph
Maximum wind gust in the last 24 hours:	95 mph
New snowfall in the last 24 hours:	2 to 8 inches
Total snow depth:	60 to 92 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.	Cloudy skies with snow showers likely.	Mostly cloudy skies with a chance of snow showers.
Temperatures:	24 to 29 deg. F.	13 to 20 deg. F.	25 to 30 deg. F.
Wind direction:	E	NE	NE
Wind speed:	Light winds	Light winds around 10 mph after midnight.	10 to 15 mph.
Expected snowfall:	Up to 2 in.	Up to 2 in.	Up to 1 in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Cloudy skies with snow showers.	Cloudy skies with snow showers likely.	Mostly cloudy skies with a chance of snow showers.
Temperatures:	19 to 24 deg. F.	10 to 15 deg. F.	21 to 26 deg. F.
Wind direction:	SE	NE	NE
Wind speed:	10 to 15 mph.	10 to 20 mph with gusts to 30 mph.	10 to 20 mph with gusts to 30 mph.
Expected snowfall:	Up to 2 in.	Up to 2 in.	Up to 1 in.