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 Sunday, December 10, 2006 at 6:55 am

Our SAC Ski Day tickets are now available. This is an excellent opportunity for you to make a donation to SAC by purchasing a heavily discounted lift ticket that was donated to us by the ski area. All of the proceeds from your ticket purchase go to SAC and you get to go skiing. This year the tickets can be bought online thanks to Snowbomb.com (just click on the link above). Our first ski day is at Mt. Rose on December 17th. We hope to see you there.

Two of three weather systems for this storm cycle have passed, leaving 6-10" of new snow across the forecast area thus far. Moderate to strong westsouthwesterly ridgetop winds have persisted throughout the storm cycle. This has caused wind loading of any snow that is available for wind transport onto lee slopes. Air temperatures fell significantly last night with the passage of the second system. The third system will impact the forecast area today from mid morning on, bringing more cold air and a few more inches of snow.

The storm snow showed variable bonding to old snow surfaces during the day yesterday, ranging from good to poor. The areas of best bonding were observed where the storm snow fell on unconsolidated snow surfaces. Poorer bonding was observed where new snow fell on hard crust surfaces created by previous easterly winds. Stability tests performed yesterday showed easy compression failure within the new snow on a grauple layer in the Mount Rose area. Moderate compression failure at the uppermost crust in the snowpack was observed both in the Mount Rose area and in several locations along the Sierra Crest. Westsouthwesterly ridgetop winds have created shallow wind slabs on NW-N-NE-E aspects below ridgelines, especially above 8,000'. Snowfall rates for this storm cycle have been fairly low, allowing for a more gradual application of stress to the snowpack, helping the lower snowpack layers to adjust to the new load. Any snowpack failure that occurs today is expected to fail within the storm snow or at the old/storm snow interface. The potential for human triggered avalanches will increase through the day today as continued moderate to strong ridgetop winds and additional snowfall deepen the present pockets of wind slab in wind loaded areas.

Near and above treeline, pockets of MODERATE avalanche danger exist on wind loaded NW-N-NE-E aspects, 35 degrees and steeper. Below treeline, avalanche danger is LOW with very isolated pockets of MODERATE danger near treeline in open, wind loaded areas where a hard crust sits at the old/storm snow interface.

Keep in mind that the overall snowpack is very shallow. You will hit rocks on your skis, snowboard, or snowmobile when you venture off of the snowpacked roads. Getting hurt this time of year makes for a very long winter. Travel at slow speeds to minimize damage to yourself and your equipment. Your best option for recreation remains xc style touring on the higher elevation roads.

Brandon Schwartz, Avalanche Forecaster

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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: 31 deg. F
Average wind direction at Sierra Crest past 24 hours: westsouthwesterly
Average wind speed at Sierra Crest past 24 hours: 52 mph
Maximum wind gust at Sierra Crest past 24 hours: 85 mph
New snow fall at 8,200 feet past 24 hours: 3-6 inches
Total snow depth at 8,200 feet: 15 inches

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Mountain Weather Forecast For Today:
Cloudy skies with snow.
Temperature forecast for 8,000 to 9,000 feet: 21 - 27 deg. F
Ridgetop winds forecast for the Sierra Crest: westsouthwesterly at 40 - 60 mph, G 80 mph
Snowfall expected in the next 24 hours: 2 - 5 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
For today, cloudy skies with occasional snow. Daytime highs 27 to 33 degrees F. Snow level around 4,000'. Snow accumulation 2 to 4 inches. Overnight lows 14 to 19 degrees F. with isolated snow showers. Snow accumulation up to 1 inch. Monday will be mostly cloudy with daytime highs 34 to 39 degrees F. Slight chance of snow showers.

Above 8000 Feet
For today, cloudy skies with periods of moderate snowfall. Daytime highs 21 to 27 degrees F. Snow accumulation 2 to 5 inches. Overnight lows 13 to 18 degrees F. with snow showers. Snow accumulation up to 1 inch. Monday will be mostly cloudy with a slight chance of snow showers. Daytime highs 29 to 35 degrees F. Moderate to strong westsouthwesterly ridgetop winds for today are expected to ease to moderate westerly on Monday.

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