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 Tuesday, December 26, 2006 at 7:06 am

The weather service has issued a high wind warning and a winter storm warning for the Tahoe area. Overnight the southwest winds increased ahead of the storm. They will continue to strengthen throughout the day as the storm arrives. This storm system will come in warm and gradually cool off as it moves through the area. Today we will see snow levels around 7800'. Tonight they will drop to lake level. By late Wednesday this storm should be almost done leaving us with 12-24" of new snow above 8000' and 6-12" below 8000'. A cold high pressure will move in behind the storm.

The current snowpack has strengthened over the last few days. The warm temperatures and rain that will occur at the start of this storm will help the new snow bond well to the existing snowpack. Any snow that accumulates in this storm will form wind slabs on the NW-N-NE-E aspects because of the strong southwest winds that will continue to blow throughout the storm. These wind slabs will start forming today above 7800' and become more widespread as the freezing levels drop and we start to see snow accumulation at the lower elevations this evening and through the night. The high wind speeds associated with this storm will cause these windslabs to form further downhill from ridge lines and even inside the trees in some areas. The windslabs will also be present in some less obvious places, so be alert for any signs of windloading and watch out for that terrain.

Today the avalanche hazard will increase throughout the day. By this afternoon human triggered avalanches will be probable above 8000' on steep windloaded NW-N-NE-E facing slopes. Any avalanches that are triggered will likely be those newly formed windslabs failing on weaknesses in the storm snow. Below 8000' it will be raining raining most of the day, so the the avalanche hazard will not increase as much until tonight when the snow levels drop.

Near and above treeline, avalanche danger is MODERATE this morning increasing to CONSIDERABLE by this afternoon. Below treeline, avalanche danger is MODERATE. Avalanche activity will be most likely on recently wind loaded NW-N-NE-E aspects 35 degrees and steeper.

Andy Anderson , Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
32 deg. F
Max. temperature at Sierra Crest past 24 hours:
32 deg. F
Average wind direction at Sierra Crest past 24 hours:
southwest
Average wind speed at Sierra Crest past 24 hours:
65 mph
Maximum wind gust at Sierra Crest past 24 hours:
115 mph
New snow fall at 8,200 feet past 24 hours:
0
Total snow depth at 8,200 feet:
33 inches
Mountain Weather Forecast For Today:
Rain and snow. Snow levels 7500'-8000'. Snow accumlations of up to 8".
Temperature forecast for 8,000 to 9,000 feet:
35 deg. F
Ridgetop winds forecast for the Sierra Crest:
southwesterly 55-75 mph, G 115 mph
Snowfall expected in the next 24 hours:
12-18 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet
For today, rain with daytime highs around 39 degrees F. Snow level 7,500' to 8000'. Winds out of the southwest at 40 to 60 mph with gusts to 80 mph. Overnight snow with lows 24 to 30 degrees F. Snow accumulation of 4-8 inches. Southwesterly winds 40 to 60 mph with gusts to 80 mph. Wednesday expect to see snow showers with snow ending in the afternoon. Snow accumulation up to 4 inches. Daytime highs around 30 degrees F. Southwesterly winds 35 to 40 mph with gusts to 50 mph.

Above 8000 Feet
For today, snow with daytime highs around 35 degrees F. Snow level 7,500' to 8000'. Snow accumulation up to 8 inches. Winds out of the southwest at 55 to 75 mph with gusts to 115 mph. Overnight snow with lows around 25 degrees F accumulations 4-8 inches. Southwesterly winds 60 to 75 mph with gusts to 115 mph. Wednesday expect to see snow showers with snow ending in the afternoon. Snow accumulation up to 8 inches. Daytime highs around 27 degrees F. Southwesterly winds 50 to 65 mph with gusts to 80 mph. The winds will decrease in the afternoon and shift to the west.

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:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.