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 high pressure ridge over the region will allow the clear and dry weather to continue. Temperatures above 7000 ft. will remain warmer than the temperatures in the valleys due to a strong inversion. Currently above 7000 ft. most sensors report temperatures in the low 30's while those sensors in mountain valleys below 7000 ft. indicate temperatures in the the teens. The forecast calls for highs in the upper 30's and low 40's today in and tomorrow in the mountains above 7000 ft. Winds decreased and shifted back to the southwest yesterday and should remain light to moderate through tomorrow.

Recent Observations:

Yesterday in the Echo Summit area (more info) and in the Ophir Creek (more info, snowpit, video) drainage, soft unconsolidated snow still existed on most of the northerly aspects. Snowpits, handpits, ski cuts on test slopes, and other observations indicated a stable snowpack in sheltered areas. On some isolated leeward terrain features, wind loading had created small shallow wind slabs. Ski cuts on these features in both areas did cause some minor cracking. In the Ophir Creek area, this cracking was limited to within a foot of a person's skis and only went about 3 inches deep in the snowpack. In the Echo Summit area, deeper cracking occurred with depths of 8-10 inches. In both of these places, the wind slabs remained small and limited to areas near ridgelines. 

In the Ophir Creek drainage, the Dec. facet layers existed within 4 ft. of the surface in some areas. Snowpit tests performed on these deeper persistent weak layers showed that they remain weak and that if they do start to collapse, the resulting fracture could travel along the weak layer (more info, snowpit, video). The tests also indicated that transmitting enough force through the snowpack to actually break these layers has become more difficult due to the strong snow above these old weaknesses.

Snowpack Concerns: Wind Slabs and Persistent Deep Slabs

5 days have passed since the last known avalanche activity. Data collected around the forecast area indicates that the snowpack continues to gain strength and that the strong snow on top of the persistent weak layers continues to insulate those layers from forces applied to the snow surface. On a regional scale, these conditions have made avalanche activity caused by a single skier, snowboarder, or snowmobiler unlikely. Some areas of unstable snow could still lurk in complex or extreme terrain in and around steep chutes, gullies, couloirs, cliffs and rock bands especially in wind loaded areas. Additionally, triggers larger than a single person recreating on a slope such as multiple people close together on the same slope, very large cornice collapses, or other avalanches could still provide the force needed to cause a failure in the older persistent weak layers. In this case large, deep, and destructive avalanches that could fracture across wide areas and far away from the trigger that caused the collapse would result. Like other avalanche activity actually triggering these persistent deep slabs has become unlikely, but if one of them does release catastrophic consequences would result.

Continue to exercise good travel techniques like moving one at time from safe zone to safe zone while in avalanche terrain. Soft snow and a sense of stability can easily impair judgement and create unsafe situations.

The bottom line:

Avalanche danger remains LOW for all elevations and aspects. LOW danger means avalanches are unlikely not that they are impossible. Isolated areas of unstable snow may exist in complex terrain in and around areas of chutes, gullies, cliffs, and exposed rocks. Continue to use normal caution when travelling in the backcountry.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	26-32 deg. F.
Max. temperature in the last 24 hours:	32-38 deg. F.
Average wind direction during the last 24 hours:	East shifting to the Southwest
Average wind speed during the last 24 hours:	15-20 mph
Maximum wind gust in the last 24 hours:	38 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	63-90 inches

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

For 7000-8000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Sunny	Clear	Sunny
Temperatures:	37-43 deg. F.	13-23 deg. F.	34-41 deg. F.
Wind direction:	Variable	Variable	Variable
Wind speed:	Light	Light	Light
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Sunny	Clear	Sunny
Temperatures:	33-40 deg. F.	23-31 deg. F.	33-40 deg. F.
Wind direction:	Southwest	Southeast	West
Wind speed:	10-15 mph	10-15 mph	around 10 mph
Expected snowfall:	O in.	O in.	O in.