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.

A inversion exists around the region with remote sensors below 7000 ft reporting temperatures in the upper 20's and low 30's while the sensors at the higher elevations indicate temperatures in the low 40's this morning. A high pressure ridge over the forecast area will keep the weather sunny and warm through tomorrow. Expect to see daytime highs in the upper 40's and low 50's in the mountains today and tomorrow. The winds have started to shift towards the southwest overnight and should start to increase over the next 36 hours ahead of an approaching cold front.

Recent Observations:

Yesterday observations on Mt. Judah showed a shallow snowpack consisting of crusts and consolidated snow. Snowpit tests and general observations indicated a generally stable snowpack in this area below 8200 ft. On Wednesday a similar snow structure existed farther south on Becker Peak. In both of these areas recent warming and rain have melted large quantities of the snowpack uncovering many previously buried rocks, stumps, and areas of bare ground.

Recent observations at higher elevations in the Mt. Rose backcountry show more consistent snow coverage; however, a persistent weak layer of soft sugary snow (facets) exists below a cohesive slab in some areas. Snowpits have shown this layer on N to NE aspects mainly above 9,500 ft. In snowpit tests, this facet layer collapsed easily and propagated cleanly, (videos, more info). This layer appears weakest on slopes that received little to no traffic prior to the most recent snowfall.

Today's Primary Avalanche Concern: Persistent Slabs

Although they have become more difficult to trigger, human triggered avalanches will remain possible in isolated areas where cohesive snow rests on top a persistent weak layer. So far this combination has only been seen in the Mt. Rose backcountry on NW-N-NE aspects above 9500 ft. Variability associated with the existence, location, strength, and coverage of both the persistent weak layer and the slab above it make this problem difficult to track and evaluate. Snowpack failure resulting from this kind of avalanche concern can occur on slopes where several people have already tested the slope on skis, boards, or sleds but have not found the right trigger point to cause a larger failure. Probing into the snowpack and digging quick snowpits can reveal whether or not this combination exists on a particular slope.

Other things to think about:

Even though LOW avalanche danger exists around most of the forecast area, this does not mean no danger remains. Some very isolated fragile wind slabs may still lurk in very isolated complex or extreme terrain. Also, the shallow early season snowpack means more exposed stumps, rocks, trees, and other very hard objects that tend to "win" when they collide with backcountry recreationalists.  

The bottom line:

Near and above treeline, isolated pockets of MODERATE avalanche danger may still exist on NW-N-NE aspects on slopes 35 degrees and steeper due to ongoing persistent slabs. For all other areas, avalanche danger is LOW. LOW danger does not mean no danger.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	37-41 deg. F.
Max. temperature in the last 24 hours:	45-50 deg. F.
Average wind direction during the last 24 hours:	East shifting to the Southwest
Average wind speed during the last 24 hours:	10 mph
Maximum wind gust in the last 24 hours:	27 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	15-30 inches

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

For 7000-8000 ft:
	Friday:	Friday Night:	Saturday:
Weather:	Sunny	Clear	Sunny
Temperatures:	46-53 deg. F.	30-38 deg. F.	45-52 deg. F.
Wind direction:	East	Southwest	Southwest
Wind speed:	10-15 mph decreasing in the afternoon	10 mph	10-15 mph
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Friday:	Friday Night:	Saturday:
Weather:	Sunny	Clear	Sunny
Temperatures:	43-51 deg. F.	31-38 deg. F.	38-48 deg. F.
Wind direction:	Southeast shifting to the Southwest	Southwest	Southwest
Wind speed:	10-15 mph with gusts to 25 mph	15-20 mph with gusts to 30 mph	15-25 mph with gusts to 35 mph
Expected snowfall:	O in.	O in.	O in.