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.

This advisory was posted on Sunday, December 31, 2006 at 7:00 am

Yesterday the temperatures warmed up across all elevations ahead of a small disturbance that should move through our area this afternoon and tonight. There is a small chance that we will see some snow this afternoon and evening; however, any accumulation will be minimal. Following this small disturbance, a high pressure ridge will again build over the area bringing cold, clear weather for the new few days. The winds are currently out of the southwest and will continue to be moderate as this small disturbance moves through. They should shift back to the north and northeast by tomorrow with the return of the high pressure ridge.

By yesterday afternoon the upper layers of the snowpack had bonded nicely to the layers below them. As the snowpack consolidates and strengthens, the areas of instability are shrinking. There are still a few small isolated pockets of hard wind slab out there that could fail with a large enough trigger such as a snowmobile or two, large cornice failure, or several skiers or boarders. A smaller trigger in the just the right spot on a steep slope could also cause these windslabs to fail. The likely trigger points include areas where the slab is thin, just below cornices and cliffs, near rocks, and convex rollovers. These slabs are most prominent on the NW aspects and will sound hollow when you step on them.

The warm temperatures across the region also destroyed most of the surface hoar that that formed over the last few days and started to form breakable crusts on the sun exposed E-SE-S-SW-W aspects. At the higher elevations the warming and refreezing has made the wind scour crusts from earlier this week even more treacherous. While you are not likely to trigger a slide on these slopes, it is very easy to go for a long, fast slide ending with a sudden stop against a tree if you happen to fall.

Luckily there is still excellent snow left over from the storm to play in. It is hiding on the mid elevation NW-N-NE aspects that have good tree cover to protect the snow from the winds.

Near and above treeline today the avalanche danger is LOW in areas that are not wind affected. There are still some areas where the avalanche danger is MODERATE on windloaded slopes steeper than 35 degrees. The most likely aspect for these hard windslabs are the NW slopes. Below treeline the avalanche danger is LOW.

Andy Anderson , Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
31 deg. F
Max. temperature at Sierra Crest past 24 hours:
41 deg. F
Average wind direction at Sierra Crest past 24 hours:
southwest
Average wind speed at Sierra Crest past 24 hours:
15-20 mph
Maximum wind gust at Sierra Crest past 24 hours:
45 mph
New snow fall at 8,200 feet past 24 hours:
0 inches
Total snow depth at 8,200 feet:
33 inches
Mountain Weather Forecast For Today:
Mostly cloudy with a slight chance of snow showers this afternoon.
Temperature forecast for 8,000 to 9,000 feet:
36 deg. F
Ridgetop winds forecast for the Sierra Crest:

southwest at 15-25 mph.
Snowfall expected in the next 24 hours:
a trace with a slight chance of up to 1"
2 Day Mountain Weather Forecast:
7000 to 8000 Feet
For today, mostly cloudy with a slight chance of snow showers this afternoon with little if any accumulation. The freezing level will be around 7000'. Winds out of the the southwest at 10-20 mph. Daytime highs around 38 degrees F. Overnight, mostly cloudy with a few lingering flurries, lows 17 to 23 degrees F. Freezing level will drop to lake level. North winds at 10-15 mph. Tomorrow, partly cloudy. Daytime highs around 42 degrees F. with winds out of the northeast at 15 to 20 mph.

Above 8000 Feet
For today, mostly cloudy with a slight chance of snow showers this afternoon with little if any accumulation. Winds out of the the southwest at 15-25 mph. Daytime highs around 36 degrees F. Overnight, mostly cloudy with a few lingering flurries, lows 18 to 24 degrees F. Northwest winds at 10-15 mph. Tomorrow, partly cloudy. Daytime highs around 40 degrees F. with winds out of the northeast at 15 to 25 mph with gusts to 45 mph.

The bottom line:

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	deg. F.
Max. temperature in the last 24 hours:	deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours:	mph
Maximum wind gust in the last 24 hours:	mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	inches

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

For 7000-8000 ft:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.