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 Monday, January 15, 2007 at 6:49 am

Another morning of cold air temperatures and moderate to strong easterly ridgetop wind is in the works this morning. Air temperatures are expected to warm today as a temperature inversion sets up over the forecast area. Temperatures in the mountains will return to near normal today and tomorrow and are expected to remain so through the rest of the week. East winds are expected to decrease during the day today. The next opportunity for light snowfall occurs Tuesday night as another weak weather system brushes by our area.

Unrelenting easterly winds over the past several days have created pockets of very small wind slab. These slabs exist in lee and cross loaded areas on a variety of aspects near and above treeline. These small slabs remain isolated, failing 2-3 inches below the snow surface in response to human triggers. Cold air and snow temperatures have allowed them to remain reactive longer than is often observed in this area. Due to the very small size and lack of propagation associated with these wind slabs, they do not pose a significant threat to backcountry travelers. Very strong temperature gradients of 3 to 5 degrees C. per 10cm of snowpack height continue to create vapor pressure gradients that cause the faceting of snow crystals. Faceting of snow crystals has been observed at all heights within the snowpack throughout the forecast area. The snowpack remains stable at this time, but overall weakening of the snowpack will continue to occur until the strong temperature gradient in the snowpack is corrected by warmer weather.

Stable hard slab conditions remain near and above treeline on all aspects. East winds over the past few days have caused a bit of damage to areas of unconsolidated snow that remained after the last snowfall. Pockets of unconsolidated snow remain below treeline on northerly aspects, but the wind has brought areas of hard slab further below treeline. This has reduced the area where a balance of quality snow and comfortable cover of rocks, stumps, and down trees exists. Be careful while traveling at speed in the lower elevation areas.

Avalanche danger remains LOW for all elevations and aspects.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 7 deg. F
Max. temperature at Sierra Crest past 24 hours: 13 deg. F
Average wind direction at Sierra Crest past 24 hours: Easterly
Average wind speed at Sierra Crest past 24 hours: 52 mph
Maximum wind gust at Sierra Crest past 24 hours: 84 mph
New snow fall at 8,200 feet past 24 hours: 0 - trace inches
Total snow depth at 8,200 feet: 39 inches

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Mountain Weather Forecast For Today:
Sunny skies
Temperature forecast for 8,000 to 9,000 feet: 23 - 27 deg. F
Ridgetop winds forecast for the Sierra Crest: easterly 20 - 30 mph, G50 mph
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
Today, sunny skies with daytime highs 27 to 32 degrees F. East winds 10 to 20 mph diminishing to 10 mph in the afternoon. Overnight, clear skies with lows 20 to 25 degrees F. East winds at 5 to 15 mph. Tuesday will be sunny with daytime highs 28 to 32 degrees F. Southeast winds at 5 to 15 mph are expected.

Above 8000 Feet
Today, sunny skies with daytime highs 23 to 27 degrees F. East winds 20 to 30 mph gusting to 50 mph decreasing to 15 to 20 mph in the afternoon. Overnight, clear skies with lows 22 to 28 degrees F. East winds at 15 to 20 mph gusting 40 to 50 mph in the evening. Tuesday will be sunny with daytime highs 26 to 30 degrees F. Southeast winds at 10 to 15 mph are expected.

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