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 21, 2008 6:46 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 with pockets of MODERATE danger near and above treeline on wind loaded N-NE-E aspects, 37 degrees and steeper. This afternoon, areas of MODERATE danger will become widespread. Below treeline, avalanche danger will remain LOW.

Another weather system will impact the forecast area today. A slight chance of snow is forecast for this morning, with a period of heavy snowfall expected to occur during the afternoon and overnight hours. Snow level is expected at 5,000' or lower for the duration of this storm. Ridgetop winds have been light from the west over the past 24 hours with a brief period of very light and variable winds overnight. Winds have shifted to the southwest this morning ahead of the approaching weather system.

Yesterday, new snow amounts of 2 to 5 inches were observed across the forecast area. Light winds formed shallow slabs on N-NE-E aspects near and above treeline. A small skier triggered avalanche occurred off of the summit of Jake's Peak (West Shore Tahoe area) at 9,050' on a NNE aspect with a slope angle of 44 degrees. The avalanche had a crown height of 3 to 5 inches, fractured 50 feet wide and ran 250 vertical feet down slope. The slab consisted of new snow measuring fist+ in hardness and failed on a higher density wind scoured old snow bed surface of 1 finger hardness. Isolated pockets of similar instability are expected to linger this morning.

After snowfall begins around noon today, avalanche danger will increase in response to snowfall rates in excess of 1 inch per hour. New snow accumulation of 4 to 6 inches is expected today between noon and 4 pm. The combination of new snow and southwest winds will increase slab formation near and above treeline during the afternoon hours. Human triggered avalanches will be possible in wind loaded areas on steep N-NE-E aspects. Natural avalanches are unlikely during the day today, but will become possible tonight as heavy snowfall continues. Below treeline, slab formation is not expected due to relatively light winds associated with today's weather system. Natural and human triggered avalanches will remain unlikely today below treeline.

The bottom line: This morning, avalanche danger is LOW with pockets of MODERATE danger near and above treeline on wind loaded N-NE-E aspects, 37 degrees and steeper. This afternoon, areas of MODERATE danger will become widespread. Below treeline, avalanche danger will remain LOW.

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): 19 deg. F
Max. temperature at Sierra Crest past 24 hours: 30 deg. F.
Average wind direction at Sierra Crest past 24 hours: West
Average wind speed at Sierra Crest past 24 hours: 11 mph
Maximum wind gust at Sierra Crest past 24 hours: 34 mph
New snow fall at 8,200 feet past 24 hours: trace inches
Total snow depth at 8,200 feet: 81 inches

Mountain Weather Forecast For Today:
Cloudy skies with heavy snowfall in the afternoon.
Temperature forecast for 8,000 to 9,000 feet: 25 to 30 deg. F
Ridgetop winds forecast for the Sierra Crest: Southwest at 20 to 30 mph with gusts to 40 mph
Snowfall expected in the next 24 hours: 8 to 12 inches

2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, cloudy skies with a slight chance of snow in the morning, heavy snowfall in the afternoon. Snow accumulation 4 to 6 inches. Daytime highs around 34 deg. F. Southwest winds at 10 to 20 mph with gusts to 25 mph. Gusts increasing to 35 mph in the afternoon.

Tonight, cloudy skies with snow. Snow accumulation 2 to 6 inches. Overnight lows 19 to 25 deg. F. Southwest winds at 10 to 15 mph with gusts to 30 mph.

For Friday, cloudy skies with snow showers likely. Snow accumulation 2 to 4 inches. Daytime highs 24 to 30 deg. F. Southwest winds at 10 to 20 mph with gusts to 35 mph.

Above 8000 Feet:
Today, cloudy skies with a slight chance of snow in the morning, heavy snowfall in the afternoon. Snow accumulation 4 to 6 inches. Daytime highs around 29 deg. F. Southwest winds at 10 to 15 mph with gusts to 25 mph. Winds increasing to 15 to 25 mph with gusts to 35 mph in the afternoon.

Tonight, cloudy skies with snow. Snow accumulation 4 to 6 inches. Overnight lows 15 to 23 deg. F. Southwest winds at 15 to 25 mph with gusts to 45 mph.

For Friday, cloudy skies with snow showers likely. Snow accumulation 2 to 4 inches. Daytime highs 18 to 24 deg. F. Southwest winds at 20 to 30 mph with gusts to 45 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.