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 8, 2008 6:32 AM
Click here for a detailed map of the SAC forecast area

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Today's Advisory:

This morning, avalanche danger is LOW for all elevations and aspects. Areas of MODERATE avalanche danger will develop at all elevations on SE-S-SW-W aspects, 37 degrees and steeper in response to daytime warming.

High pressure is firmly in place over the forecast area. Air temperatures will warm above yesterday's highs again today at all elevations. Ridgetop winds shifted to the north and became light overnight. Winds are forecast to remain light through Saturday.

Yesterday, warming daytime air temperatures created small areas of wet snow instability in the form of roller balls on SE-S-SW-W aspects below 7,000' in the northern portion of the forecast area and below 9,000' in the southern portion of the forecast area. The top 4 to 6 inches of the snowpack on southerly aspects started melting and became wet by mid morning. Northerly aspects above 7,000' have yet to undergo melt-freeze conditions, still holding on to a cold snowpack. The recent storm snow continues to show increasing layer bond strength on all aspects. Snowpit data and layer bonding tests performed within the top half of the snowpack at 9,600' on a NW aspect near treeline on Tryon Peak (Ebbets Pass area) and at 7,500' on a N aspect above treeline on Signal Peak (Donner Summit area) both yielded only a single hard force shear failure within the pit wall.

Below freezing air temperatures at all elevations has allowed areas where the snowpack melted yesterday to refreeze overnight. Northerly aspects will continue to hold cold and unconsolidated surface snow that is well bonded to the snowpack layers below. As daytime warming occurs, human triggered avalanches involving the top several inches of wet surface snow will become possible on steep sun exposed SE-S-SW-W aspects. Gradual warming over the past several days has allowed the snowpack to adjust to rising air temperatures. As a result, natural avalanche activity is an unlikely event today. Any avalanche activity that does occur is expected in response to human triggering.

The bottom line: This morning, avalanche danger is LOW for all elevations and aspects. Areas of MODERATE avalanche danger will develop at all elevations on SE-S-SW-W aspects, 37 degrees and steeper in response to daytime warming.

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

Brandon Schwartz, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 21 deg. F
Max. temperature at Sierra Crest past 24 hours: 31 to 36 deg. F, warmest in the south
Average wind direction at Sierra Crest past 24 hours: West
Average wind speed at Sierra Crest past 24 hours: 23 mph
Maximum wind gust at Sierra Crest past 24 hours: 61 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 90 inches

Mountain Weather Forecast For Today:
Sunny skies with warming air temperatures.
Temperature forecast for 8,000 to 9,000 feet: 35 to 41 deg. F
Ridgetop winds forecast for the Sierra Crest: North at 10 to 15 mph.
Snowfall expected in the next 24 hours: 0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, sunny skies with daytime highs 39 to 45 deg. F. Variable winds up to 10 mph.

Tonight, clear skies with overnight lows 28 to 35 deg. F. Downslope winds up to 5 mph.

For Saturday, sunny skies with daytime highs 42 to 48 deg. F. Light winds becoming southwest up to 10 mph.

Above 8000 Feet:
Today, sunny skies with daytime highs 35 to 41 deg. F. North winds at 10 to 15 mph.

Tonight, clear skies with overnight lows 28 to 35 deg. F. East winds at 10 to 15 mph.

For Saturday, sunny skies with daytime highs 38 to 44 deg. F. Southwest winds at 10 to 15 mph with gusts to 25 mph 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:
	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.