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 February 6, 2008 7:00 AM
Click here for a detailed map of the SAC forecast area

1_Low
Today's Advisory:

The avalanche danger is LOW on all elevations and aspects. LOW danger does not mean no danger, and small isolated pockets of instability could still exist. Continue to use safe travel practices and normal caution.

This morning remote sensors indicate that warming due to the high pressure ridge over the area began late last night. Today northerly flow should continue allowing the north and east winds to remain until a minor system moves past the northern end of the froecast area tonight. This system should cause the winds to shift back to the west and southwest, bring some cloud cover to the area, and maybe a few small isolated snow showers north of Highway 50 tonight and tomorrow morning.

The east winds stripped most of the unconsolidated snow and recently formed wind slabs from the N-NE-E aspects near and above treeline leaving a hard wind scoured surface behind. Some of that transported snow was deposited onto scoured W-SW-S facing slopes where significant anchors still exist in many places. the strong winds also cross loaded some NW and SE facing aspects. Small test slopes on steep cross loaded NW aspects did crack and fail with a skier's weight during the morning yesterday in the Mount Judah area. By mid afternoon slopes like this became harder to trigger as settlement occurred in the new snow. Snow pit tests from a protected NE aspect on the Mount Judah area also showed the bonds within the upper snow pack gaining strength. Today a combination of milder temperatures, continued scouring of traditional avalanche start zones, less snow transport and deposition, and continued bonding in the snow pack will make most avalanche activity involving these wind slabs unlikely.

These wind slabs are not the only concern for today. with temperatures forecast to climb sharply some small instabilities could form due to day time warming. The east winds and initial cold air temperatures should keep the warming from rising much above freezing today making significant wet snow instabilities unlikely.

The LOW danger rating does not mean that everything is safe in the mountains today. Isolated areas of instability may still exist especially in steep, cross loaded couloirs. Small instabilities could also lurk in other areas where significant previous snow cover provides a smooth consistent bed surface for newly formed wind slabs. look for ripples, drifts, cornices , and blowing snow to help determine which slopes are wind loaded. These instabilities should be rare today. Also some roller balls and pin wheels could start to occur on steep southerly slopes due to daytime warming even though significant wet snow instabilities are unlikely.

The bottom line: The avalanche danger is LOW on all elevations and aspects. LOW danger does not mean no danger, and small isolated pockets of instability could still exist. Continue to use safe travel practices and normal caution.

Please send us your snow, weather, and avalanche observations by clicking the submit observations link on our contact page.

Andy Anderson, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 18 deg. F
Max. temperature at Sierra Crest past 24 hours: 18 deg. F
Average wind direction at Sierra Crest past 24 hours: east north east
Average wind speed at Sierra Crest past 24 hours: 45 mph
Maximum wind gust at Sierra Crest past 24 hours: 80 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 97 inches
Mountain Weather Forecast For Today:
Mostly sunny with some high clouds developing this afternoon.
Temperature forecast for 8,000 to 9,000 feet: 27 to 33 deg. F
Ridgetop winds forecast for the Sierra Crest: Northeast at 20 to 35 mph with gusts to 70 mph shifting to the northwest and decreasing to 10 to 20 mph this afternoon.
Snowfall expected in the next 24 hours: 0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, mostly sunny with some high clouds developing this afternoon. Daytime highs 30 to 36 deg. F. East winds at 5 to 10 mph decreasing in the afternoon.

Tonight, mostly cloudy with a slight chance of snow showers north of highway 50. Overnight lows 18 to 24 deg. F. Southwest winds at 10 to 15 mph with gusts to 30 mph.

For Wednesday, partly cloudy with a slight chance of snow showers north of highway 50. Daytime highs 33 to 38 deg. F. West winds at 15 to 20 mph with gusts to 35 mph decreasing in the afternoon.

Above 8000 Feet:
Today, mostly sunny with some high clouds developing this afternoon. Daytime highs 27 to 33 deg. F. Winds out of the northeast at 20 to 35 mph with gusts to 70 mph shifting to the northwest and decreasing to 10 to 20 mph this afternoon.

Tonight, mostly cloudy with a slight chance of snow showers north of highway 50. Overnight lows 17 to 22 deg. F. West winds at 20 to 35 mph with gusts to 60 mph.

For Wednesday, partly cloudy with a slight chance of snow showers north of highway 50. Daytime highs around 32 deg. F. West winds at 25 to 35 mph with gusts to 60 mph decreasing in the afternoon.

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.