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.

High pressure will continue to build over the forecast area today. Sunny skies, light winds, and well above freezing air temperatures are forecast for all elevations. Remote sensors are indicating that an air temperature inversion is in place over much of the forecast area with air temperatures below 7,000' in the teens and 20s while air temperatures above 7,000' are in the 20s and 30s. Maximum daytime air temperatures are expected to reach into the 40s today for areas above 7,000'. Ridgetop winds remain out of the northeast to east this morning, having decreased from moderate to light in speed yesterday afternoon. Light winds are expected to continue this morning before becoming calm in many locations by this afternoon. Sunday's forecast calls for sunny skies, light ridgetop winds, and a few degrees of additional warming at the lower and middle elevations.

Recent Observations:

Observations were made yesterday on Tamarack Peak (Mount Rose area) and at the site of Thursday's Polaris Point avalanche accident (Ward Canyon/Blackwood area). Snowpit data collected in both areas in near treeline terrain on N-NE aspects indicated a trend of strengthening of short lived weak layers within the recent storm snow, in the frequently overstated way that is the stereotype of the Sierra Nevada snowpack. What is not at all typical for this region is the ongoing instability of the persistent weak layer of crusts and faceted snow just below the base of the recent storm snow. Propagation tests indicated that this crust/facet weak layer still holds the potential to allow fractures to travel significant distances through the snowpack, keeping concerns for human triggered deep slab avalanches ongoing (click here for photos, video pit profiles, and more info).

Today's Primary Avalanche Concern: Persistent Deep Slabs

With the recent storm snow having settled and gained strength, it is now a cohesive slab 2 to 4 feet thick sitting on top of the persistent weak layer of crusts and facets that formed in late January and early February. Triggering slab avalanches that fail within the recent new snow is unlikely at this time as the area of greatest relative weakness has shifted deeper within the snowpack to the crust/facet layer just below the bottom of the recent storm snow. This is where any snowpack failure at this time is likely to occur. This weak layer exists on NW-N-NE aspects both above and below treeline. Digging into the snowpack in these areas reveals a very easily identifiable layer and snow crystal change at the bottom of the storm snow that is obvious to both sight and feel. Large human triggered deep slab avalanches remain possible today both above and below treeline on NW-N-NE aspects. Areas near exposed rock outcrops and other similar trigger points are locations where triggering a deep slab avalanche is more likely.

Today's Secondary Avalanche Concern: Warming Instability

Areas of wet snow instability will form today on E-SE-S-SW-W aspects at all elevations. Natural and human triggered wet loose snow avalanche activity and roller ball activity are expected as the recent new snow transitions from unconsolidated storm snow to consolidated melt-freeze conditions. This will be fueled by above freezing air temperatures, minimal convective cooling of the snow surface by wind, and March levels of incoming solar radiation. Be conservative with travel above cliff bands, gullies, and other terrain traps that greatly magnify the consequences of being caught a carried by an otherwise inconsequential small loose snow avalanche.

The bottom line:

Avalanche danger is MODERATE both above and below treeline on NW-N-NE aspects on slopes 35 degrees and steeper due to ongoing deep slab instability. MODERATE avalanche danger is expected today both above and below treeline on E-SE-S-SW-W aspects on slopes 35 degrees and steeper due to wet snow instability forming in response to daytime warming.

While natural avalanche activity has become unlikely, large destructive human triggered avalanches remain possible today.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	24 to 31 deg. F.
Max. temperature in the last 24 hours:	30 to 41 deg. F.
Average wind direction during the last 24 hours:	Northeast
Average wind speed during the last 24 hours:	19 mph
Maximum wind gust in the last 24 hours:	37 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	32 to 58 inches

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

For 7000-8000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Sunny skies.	Clear skies.	Sunny skies.
Temperatures:	42 to 47 deg. F.	29 to 38 deg. F.	44 to 51 deg. F.
Wind direction:	E	Variable	Variable
Wind speed:	10 to 15 mph in the morning, becoming light.	Light winds.	Light winds.
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Sunny skies.	Clear skies.	Sunny skies.
Temperatures:	40 to 45 deg. F.	27 to 37 deg. F.	41 to 46 deg. F.
Wind direction:	E	Variable	SW
Wind speed:	15 to 20 mph with gusts to 35 mph in the morning, becoming light.	Light winds.	Light winds becoming 10 to 15 mph with gusts to 25 mph in the afternoon.
Expected snowfall:	O in.	O in.	O in.