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 Friday, December 8, 2006 at 7:59 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.

There are currently two storm systems approaching our area. The first is expected to bring snow tonight. Ridgetop winds are already increasing ahead of the approaching system. A second system follows early next week. Right now several models and forecasts show a small amount of accumulation out of these storms.

Our snowpack is still shallow and variable. The variation in snow depth and surface conditions is easy to see. In some places the change from dirt to snow or crust to powder happens multiple times in a 10ft x10ft area. This obvious variation points to great variation in the snowpack layers as well. There are melt / freeze crusts on open south through west facing aspects below 8000'. Above that elevation these crusts give way to pockets of heavy wet snow and dense wind slab deposited by the north and east winds that followed our last storm. These winds scoured any exposed north through east aspects. In several areas along the crest above 8000' and in the Mount Rose area above 8500', there are now patches of bare ground exposed in the north through east start zones. On the heavily scoured NE aspects and on most of the south through west aspects where the snowpack is shallow enough, the warm temps and solar radiation can penetrate into the bottom layers and help the snow grains to bond together. The more sheltered northerly aspects still have some surprisingly good snow sitting on top of an earlier melt freeze crust. These north through east aspects have remained considerably colder since the sun rarely hits them this time of year. Some near surface faceting exists on these aspects and even some surface hoar growth on the most sheltered north facing aspects due to the calm clear weather of the past several days. Underlying these layers are dense wind slabs sitting on top of well developed facets and depth hoar.

Even though natural or human triggered avalanches are unlikely right now, the current snowpack is not ready to take much additional loading before it fails. As we start to get more snow, keep an eye on both the surface weak layers (the crusts, facets, and surface hoar) and the weaknesses buried in the snowpack (mostly the facets above the uppermost crust) as well as bonding at the old/new snow interface.

If you are getting out on the snow please watch out for all the rocks, trees, logs, and other obstacles that are just barely covered. They will hurt you and your skis, boards, or sleds when you hit them. Now is a great time for getting your snow fix on XC skis, or snowmobiling on the snow covered roads.

Andy Anderson and Brandon Schwartz, Avalanche Forecasters

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 39 deg. F
Max. temperature at Sierra Crest past 24 hours: 47 deg. F
Average wind direction at Sierra Crest past 24 hours: southwesterly
Average wind speed at Sierra Crest past 24 hours: 20 mph
Maximum wind gust at Sierra Crest past 24 hours: 62 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 11 inches

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Mountain Weather Forecast For Today:
Mostly cloudy skies.
Temperature forecast for 8,000 to 9,000 feet: 38 - 45 deg. F
Ridgetop winds forecast for the Sierra Crest: southwesterly at 35 - 50 mph, G 70 mph
Snowfall expected in the next 24 hours: 3 - 6 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
For today, mostly cloudy skies with daytime highs 45 to 50 degrees F. Increasing clouds overnight with snow developing after midnight. Snow level 6,500'. Snow accumulation 2 to 5 inches. Overnight lows 28 to 33 degrees F. Saturday will be mostly cloudy with daytime highs 29 to 34 degrees F. Light snowfall expected. Snow level 6,500'. Snow accumulation 1 to 3 inches.

Above 8000 Feet
For today, mostly cloudy skies with daytime highs 38 to 43 degrees F. Increasing clouds overnight with snow developing after midnight. Snow accumulation 3 to 6 inches. Overnight lows 24 to 29 degrees F. Saturday will be mostly cloudy with continued light snowfall. Daytime highs 25 to 30 degrees F.. Moderate to strong westsouthwesterly ridgetop winds for today are expected to continue through Saturday.

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.