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 Friday, December 29, 2006 at 7:00 am

While the high pressure remains over our area today, the valley temperatures will stay cold. Above 7000 feet the temperatures will warm up and become much warmer than they have been for the last few days. This inversion should start to break up as the high pressure moves farther east on Saturday. The northeast winds will remain strong for the morning but should diminish through out the day.

The northeast wind continued to transport snow onto leeward slopes all day yesterday. In addition to loading the southwesterly slopes, the winds cross loaded the NW and SE slopes. The windslabs deposited by the northeast winds are stiff and dense. They are sitting on top of a mix of unconsolidated snow and crusts left after the previous storm. The interface between these layers fails easily when a small area is isolated. However, the slab is so cohesive and strong that it spreads out the force of a skier or snowboarder well and makes it hard to transmit force to down to the weak interface. A larger trigger such as a snowmobiler, large cornice failure, or several people on the same slope could transmit force through the slab and trigger an avalanche. Below treeline these windslabs are isolated and small. Above treeline they become larger and more extensive. Even though it may be hard to initiate a fracture, these windslabs will propagate fractures easily. Try to avoid places where will be easier to transmit force through windslab down to the weaker interface below it. These likely trigger points include areas where the slab is thin, just below cornices and cliffs, near rocks, and convex rollovers. The windslabs leftover from the storm on the N-NE-E aspects have shrunk as the northeast wind continues to blow and now only remain as very small isolated pockets that are unlikely to produce any serious avalanche activity.

Near and above treeline, avalanche danger is MODERATE. Below treeline, avalanche danger is MODERATE. Avalanche activity will be most likely on recently wind loaded NW and SE aspects 35 degrees and steeper.

Andy Anderson , Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
28 deg. F
Max. temperature at Sierra Crest past 24 hours:
28 deg. F
Average wind direction at Sierra Crest past 24 hours:
Northeast
Average wind speed at Sierra Crest past 24 hours:
60 mph
Maximum wind gust at Sierra Crest past 24 hours:
113 mph
New snow fall at 8,200 feet past 24 hours:
0 inches
Total snow depth at 8,200 feet:
35 inches
Mountain Weather Forecast For Today:
Partly cloudy
Temperature forecast for 8,000 to 9,000 feet:
38 deg. F
Ridgetop winds forecast for the Sierra Crest:
northeast gusting to 50 mph this morning and diminishing to a steady northeast wind of 10-20 mph by this afternoon.
Snowfall expected in the next 24 hours:
0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet
For today, partly cloudy with winds out of the the northeast at 10-15 mph. Daytime highs 33-39 degrees F. Overnight, clear with lows 17 to 27 degrees F. North winds at 10-15 mph. Tomorrow, partly cloudy with daytime highs around 40 degrees F. The wind should shift to the west at 10 to 15 mph.

Above 8000 Feet
For today, partly cloudy with winds gusting to 50 mph this morning and diminishing to a steady northeast wind of 10-20 mph by this afternoon. Daytime high around 38 degrees F. Overnight, clear with lows around 28 degrees F. North winds at 15-25 mph shifting to the northwest after midnight. Tomorrow, partly cloudy with daytime highs around 38 degrees F. The wind should shift to the west at 15 to 20 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:
	Friday:	Friday Night:	Saturday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Friday:	Friday Night:	Saturday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.