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 of two small low-pressure systems should reach the forecast area this afternoon. The winds have already shifted to the southwest and started to increase ahead of this system with winds averaging 20mph over the Sierra Crest this morning. Snow levels should stay high today (between 7500' and 8000'), but over the next 24 hours they should drop to between 6000' and 7000'. The second system should reach the area tomorrow morning bringing lower temperatures and more southwest wind. Neither of these systems has much water associated with them. The forecast only calls for a 30-40% chance of precipitation through Saturday. Total precipitation amounts should be less than 1 inch of snow above 8000'. Below 8000' this precip should fall as a mix of rain and snow.

Observations:

Observations across the forecast area this week show a stable snowpack that continues to gain strength. The weak, sugary crystals near the base of the snowpack have finally changed into more rounded (stronger) snow that can support the snowpack. Yesterday, observations on Mt. Judah (Donner Summit area) revealed that Wed. night's rain never refroze. This rain and warm temperatures during the day yesterday left the snow surface wet and soft on all aspects up to the summit at 8200'. As the skies cleared yesterday afternoon, the snow surface on some of the shaded N-NE aspects started to refreeze as the snowpack radiated heat out into the clear sky. Some small roller-balls and wet-snow sluffs did occur yesterday; however, none of these were large enough to pose much threat to backcountry travelers. 

Avalanche concerns:

Most avalanche activity will remain unlikely today. The winds could transport snow today; however, very little snow remains available for transport, and the forecast calls for very little new snow over the next 24 hrs. This lack of transportable snow will prevent windslabs from forming on leeward slopes. The radiational cooling and colder overnight temperatures should have allowed most of the snow surfaces to refreeze last night. Expect most aspects up to 9000' to have firm refrozen snow on them this morning. Warm daytime temperatures may soften some of the more southerly aspects by this afternoon. The snow surface should not soften as much today as it has over the last few days due to cooler temperatures and less sunshine. Less warming combined with a solid refreeze should prevent widespread wet snow instabilities from forming today. If the sun does come out today or if light rain falls on the snow again, enough melting could occur for some small wet snow instabilities like sluffs and roller-balls to form. Slab avalanche activity remains unlikely.

The bottom line:

Avalanche danger is LOW for all elevations and aspects. Normal caution is advised. If more precipitation falls than the forecast calls for, the avalanche danger may increase.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	38-40 deg. F.
Max. temperature in the last 24 hours:	40 deg. F.
Average wind direction during the last 24 hours:	East shifting to the southwest
Average wind speed during the last 24 hours:	15 mph
Maximum wind gust in the last 24 hours:	28 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	33-62 inches

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

For 7000-8000 ft:
	Friday:	Friday Night:	Saturday:
Weather:	Mostly cloudy this morning becoming cloudy the afternoon with a chance of rain or snow. Snow level 7500ft. to 8000ft.	Cloudy with a 40% chance of snow.	Cloudy with a 30% chance of snow.Snow level 6000 ft. to 7000 ft.
Temperatures:	38-45 deg. F.	23-30 deg. F.	36-43 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	10 mph	10-15 mph	10 mph
Expected snowfall:	trace in.	trace in.	trace in.
For 8000-9000 ft:
	Friday:	Friday Night:	Saturday:
Weather:	Mostly cloudy this morning becoming cloudy the afternoon with a chance of rain or snow.	Cloudy with a 40% chance of snow.	Cloudy with a 30% chance of snow.
Temperatures:	35-42 deg. F.	22-29 deg. F.	33-40 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	10-15 mph with gusts to 30 mph	10-20 mph with gusts to 35 mph	10-15 mph
Expected snowfall:	trace in.	trace in.	trace in.