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 7, 2008 6:56 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 on SE-S-SW aspects, 37 degrees and steeper in response to daytime warming.

A weather system is passing to the north of the forecast area today. Partly cloudy skies and moderate to strong ridgetop winds are expected over the forecast area. Warm air associated with the passing weather system has moved into the forecast area overnight. Some remote sensors are reporting above freezing air temperatures for areas below 8,000 feet in elevation. Other sensors at similar elevation are reporting air temperatures in the upper 20s. West winds are beginning to increase in speed this morning and are forecast to continue through this evening.

Yesterday, warming daytime air temperatures created small areas of wet snow instability in the form of roller balls on many SE-S-SW aspects below 9,000'. The top 4 to 6 inches of the snowpack on southerly aspects started melting and became wet by mid day. Northerly aspects did not undergo melt-freeze conditions. The recent storm snow continues to show increasing layer bond strength. Layer bonding tests performed within the top half of the snowpack at 9,100' on the E aspect Fireplug slope near Tamarack Peak (Mount Rose area) and at 7,500' on SE aspects above the Alpine Meadows Road (Between Alpine Meadows and Squaw Valley) both yielded moderate to hard force shears, mostly of rough shear quality (Q3).

Radiational cooling has allowed the snowpack to refreeze overnight at all elevations on sun exposed southerly aspects. 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 aspects. Avalanche activity is unlikely today in all other areas.

The bottom line: This morning, avalanche danger is LOW for all elevations and aspects. Areas of MODERATE avalanche danger will develop on SE-S-SW 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): 28 deg. F
Max. temperature at Sierra Crest past 24 hours: 29 deg. F
Average wind direction at Sierra Crest past 24 hours: West
Average wind speed at Sierra Crest past 24 hours: 19 mph
Maximum wind gust at Sierra Crest past 24 hours: 49 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 91 inches
Mountain Weather Forecast For Today:

Partly cloudy skies with warming air temperatures.
Temperature forecast for 8,000 to 9,000 feet: 35 to 39 deg. F
Ridgetop winds forecast for the Sierra Crest: West at 25 to 35 mph with gusts to 70 mph.
Snowfall expected in the next 24 hours: 0 inches

2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, partly cloudy skies with daytime highs 37 to 43 deg. F. West winds at 5 to 10 mph, increasing to 15 to 25 mph with gusts to 40 mph by the afternoon.

Tonight, partly cloudy skies with overnight lows 24 to 29 deg. F. West winds at 10 to 15 mph with gusts to 30 mph in the evening, becoming light by midnight.

For Friday, mostly sunny skies with daytime highs 38 to 45 deg. F. Light winds.

Above 8000 Feet:
Today, partly cloudy skies with daytime highs 35 to 39 deg. F. West winds at 25 to 35 mph with gusts 60 to 70 mph.

Tonight, partly cloudy skies with overnight lows 27 to 32 deg. F. West winds at 20 to 30 mph with gusts to 50 mph. Winds shifting to northwest at 15 to 25 mph with gusts to 40 mph after midnight.

For Friday, mostly sunny skies with daytime highs around 38 deg. F. North winds at 10 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:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.