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 Thursday, January 18, 2007 at 12:06 pm

Our current financial situation is still in jeopardy. (for details click here) We still do not have enough money to finish out this season. We need your help to make our second fundraiser this Sunday at Kirkwood a success. By purchasing a $40 SAC ski day lift ticket online before Sunday at Snowbomb.com, you will get to ride the lifts at Kirkwood for 40% off of their normal rate. The entire purchase price of $40 goes directly to supporting the Sierra Avalanche Center. This event is much more than just a day of cheap resort skiing. We will be there all day to meet you and answer your questions. Lots of other folks who are traditionally in the backcountry will also be there trading stories and making turns together. On top of the fun, we will have some great raffle prizes to give away. If you can't make it but would still like to help out, please make a tax deduct able donation directly to us via Paypal or by sending a check to our address listed above, c/o the Truckee Ranger Station. Thank you for your support.

An air temperature inversion is in place, bringing warmer air temperatures to the upper elevations than to the valley floors. Clear weather with gradual warming each day is expected to continue for the next several days. Moderate east winds are expected to continue through tonight, before beginning to ease on Friday.

Cold snowpack temperatures that developed last week are persistent and slow to warm, despite warmer daytime air temperatures. The strong temperature gradient of 3 to 5 degrees C per 10cm of snowpack height that was observed within the snowpack over the past week has decreased to 2 to 3 degrees C. per 10 cm of height. This is still a strong enough temperature gradient to create enough vapor pressure to cause faceting of snow crystals within the snowpack. Field observations have shown continued faceting of snow crystals, especially in the upper layers of the snowpack and near crusts. The rate of faceting has slowed over the past few days in response to gradual warming, but the process has not yet stopped. Layer bonding tests are beginning to show new hard force shears on faceted layers that were not producing failures 3 to 4 days ago. Overall, the snowpack remains stable at this time, but it is gradually loosing strength.

Snow surface conditions remain variable by aspect and elevation. There are two options for the best riding conditions, given the current weather and snowpack. Below treeline, some pockets of shallow, unconsolidated snow linger on northerly aspects that are well protected from east winds. Above treeline, snow covered south aspects in the 8,000' to 8,500' elevation range are receiving sufficient sun to soften just enough for descent turns around 2:00pm. This is somewhat dependent on local winds affecting snow surface temperatures, so have a look around. Above treeline on all aspects, stable hard slab conditions exist, with thin melt-freeze crusts found on southerly aspects. Near and below treeline is a mix of melt-freeze crust, stable hard slab, and unconsolidated snow depending on aspect. Now would also be a great time to get out and practice your rescue skills. There are beacon basins located at the base of Squaw Valley and Kirkwood.

Avalanche danger remains LOW for all elevations and aspects.

The next scheduled update to this advisory will occur tomorrow afternoon.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 14 deg. F
Max. temperature at Sierra Crest past 24 hours: 20 deg. F
Average wind direction at Sierra Crest past 24 hours: easterly
Average wind speed at Sierra Crest past 24 hours: 45 mph
Maximum wind gust at Sierra Crest past 24 hours: 64 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 38 inches

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Mountain Weather Forecast For Today:
Sunny skies
Temperature forecast for 8,000 to 9,000 feet: 31 - 35 deg. F
Ridgetop winds forecast for the Sierra Crest: easterly 20 - 30 mph with gusts to 60 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 32 to 36 degrees F. East winds 15 to 20 mph. Overnight, clear skies with lows 11 to 21 degrees F. East winds at 10 to 20 mph. Friday will be sunny with daytime highs 35 to 39 degrees F. East winds at 10 to 15 mph are expected.

Above 8000 Feet
Today, sunny skies with daytime highs 31 to 35 degrees F. East winds 20 to 30 mph with gusts to 60 mph. Overnight, clear skies with lows 16 to 24 degrees F. East winds 20 to 30 mph with gusts to 50 mph. Friday will be sunny with daytime highs 34 to 38 degrees F. East winds at 15 to 20 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:
	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.