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 low pressure system in the Pacific Northwest should cause increasing cloud cover over the forecast area through Thursday. This cloud cover should keep temperatures cooler over the next 24 hours as well. The forecast calls for a second stronger system to move into the Pacific Northwest overnight on Thursday. The cold front associated with this system should reach the Central Sierra by Friday evening and should bring even cooler temperatures. This second storm system will also bring a 60% chance of snow to the forecast area during the day on Friday with 4 to 10 inches of accumulation possible. Check the Thursday's NWS backcountry forecast for updated snowfall amounts. 

Yesterday, observations in the Mount Rose area and on Hidden Peak continued to show variable snow surface conditions with stiff wind affected surface snow on open N-NE-E aspects and sun-crusts on the southerly aspects. Soft, unconsolidated surface snow remains in areas protected from the NE winds on northerly aspects above 7500'. Observers reported surface hoar in the Mount Rose area and near-surface facets in the Hidden peak area on some of these protected slopes. If sun, wind, or warmth does not destroy these fragile crystals before Friday's snow, they could become failure layers for avalanche activity. Snowpit tests from both of these areas show bonds between and within layers in the snowpack gaining strength. These tests also indicate that the older weak layers of facets still exist near the bottom of the snowpack. Observers reported some small surface sluffs on southerly sun exposed aspects in the Mount Rose area.

Dangerous avalanche activity is unlikely today. However, isolated hard wind slabs near and above treeline on wind affected slopes that are 37 degrees or steeper still warrant extra caution because of their consequences. These slabs should be hard to trigger and are unlikely to produce avalanches today. However, there is a small chance that the right trigger in the right spot could result in a very isolated human-triggered slab avalanche. These unlikely avalanches could be large and would be a surprise to the person who triggers them due to otherwise widespread stable conditions. Use good travel habits to minimize risk.

Surface instabilities due to daytime warming should be unlikely today due to the increased cloud cover and cooler temperatures. If the clouds do not materialize, small point releases and pinwheels could form again today.

The bottom line:

The avalanche danger is LOW for all elevations and aspects. Human triggered avalanches are unlikely but not impossible today. Isolated areas of instability may exist. This advisory will be updated on January 2nd, 2009 by 7:00 am.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	31 deg. F.
Max. temperature in the last 24 hours:	37 deg. F.
Average wind direction during the last 24 hours:	West southwest
Average wind speed during the last 24 hours:	20-25 mph
Maximum wind gust in the last 24 hours:	39 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	56-65 inches

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

For 7000-8000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Partly cloudy this morning becoming mostly cloudy this afternoon	Mostly cloudy	Mostly cloudy
Temperatures:	34-41 deg. F.	20-27 deg. F.	36-43 deg. F.
Wind direction:	West shifting to the south this afternoon	West	Southwest
Wind speed:	10-15 mph	10-15 mph with gusts to 25 mph	10-15 mph with gusts to 25 mph
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Partly cloudy this morning becoming mostly cloudy this afternoon	Mostly cloudy	Mostly cloudy
Temperatures:	32-39 deg. F.	21-28 deg. F.	32-39 deg. F.
Wind direction:	West shifting to the south this afternoon	West	West
Wind speed:	10-15 mph with gusts to 30 mph	10-15 mph with gusts to 35 mph increasing to 15-25 mph with gusts to 45 mph after midnight	10-20 mph with gusts to 30 mph
Expected snowfall:	O in.	O in.	O in.