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, February 12th, 2007 at 6:59 am

The bottom line: Near and above treeline, avalanche danger is MODERATE on recently wind loaded NW-N-NE-E aspects 35 degrees and steeper. Below treeline, avalanche danger is LOW. Backcountry travelers should not be surprised by the occurrence of human triggered of avalanches today. Natural avalanches are unlikely.

The series large storm systems that impacted the forecast area over the past several days has ended. A small amount of moisture is lingering over the forecast area. This is expected to cause continued snow shower activity over the Sierra Crest today and Tuesday, especially during the afternoon hours. Ridgetop winds have decreased overnight and are expected to remain moderate southwesterly today. Colder air has moved into the forecast area and lower high temperatures are expected today.

Storm totals are running to 36-42 inches of snowfall since Wednesday night. An additional 2-5 inches of new snow was added yesterday. Heavy wind loading was observed in many areas, especially in the northern half of the forecast area. Weak shears were observed yesterday within the recent storm snow on a layer of rimed crystals. This was evident both along the Sierra Crest and in the Mount Rose area. Weak shears were also observed within the storm snow just below the layer of wet snow that was deposited on top of drier snow during a period of rising snow levels that occurred Saturday night. As bonding within the snowpack increases today, these shears will become less prone to failure. Around 2 inches of snowpack settlement was observed overnight at the 8,000' level.

Yesterday in the northern half of the forecast area, isolated slab avalanches were reported above treeline on wind loaded NW-N-NE-E aspects. One natural avalanche was reported to have occurred Saturday night while many others were explosive triggered Sunday morning. Small wind loaded test slopes remained active yesterday in the northern half of the forecast area. Minimal avalanche activity was observed in the southern half of the forecast area.

As ridgetop winds decrease today, a significant reduction in the amount of wind loading is expected. Wind slabs and large, weak cornices have formed on NW-N-NE-E aspects. Areas of snowpack instability will linger today beneath cornice features in near and above treeline areas. Human triggered avalanches remain possible in these areas. Backcountry travelers should not be surprised by human triggered avalanches occurring within the storm snow on recently wind loaded NW-N-NE-E aspects, 35 degrees and steeper.

The bottom line: Near and above treeline, avalanche danger is MODERATE on recently wind loaded NW-N-NE-E aspects 35 degrees and steeper. Below treeline, avalanche danger is LOW. Backcountry travelers should not be surprised by the occurrence of human triggered avalanches today. Natural avalanches are unlikely.

At this time, we have not raised enough money to meet our operating budget for this year. If you use this service with any regularity and would like to continue to do so, please show your support for the Sierra Avalanche Center. You may make a tax deductible donation directly to us via Paypal or by sending a check to our address listed above, c/o the Truckee Ranger Station. A financial graph showing the current fundraising and budget numbers is available by clicking here. The financial support already received this winter from a variety of users is greatly appreciated.

Brandon Schwartz, Avalanche Forecaster

Today's Central Sierra Weather Observations:

0600 temperature at Sierra Crest (8,700 feet): 22 deg. F
Max. temperature at Sierra Crest past 24 hours: 28 deg. F
Average wind direction at Sierra Crest past 24 hours: westsouthwesterly
Average wind speed at Sierra Crest past 24 hours: 45 mph
Maximum wind gust at Sierra Crest past 24 hours: 87 mph
New snow fall at 8,200 feet past 24 hours: 2 - 5 inches
Total snow depth at 8,200 feet: 59 inches

Mountain Weather Forecast For Today:

Mostly cloudy skies with snow showers, most intense in the afternoon .
Temperature forecast for 8,000 to 9,000 feet: 17 - 27 deg. F
Ridgetop winds forecast for the Sierra Crest: Southwesterly 20 - 30 mph, gusting to 40 mph
Snowfall expected in the next 24 hours: 1 - 3 inches

2 Day Mountain Weather Forecast:

7000 to 8000 Feet
Today, mostly cloudy skies with snow showers. Showers increasing in intensity in the afternoon. Snow accumulations up to 2 inches. Southwest winds at 10 to 20 mph. Daytime highs 26 to 31 degrees F. Tonight, mostly cloudy with scattered snow showers. Snow accumulation up to 1 inch. Lows 15 to 20 degrees F. West winds at 5 to 15 mph. Tuesday, mostly cloudy with scattered snow showers. Snow accumulation up to 1 inch. North winds at 10 to 20 mph. Daytime highs 28 to 33 degrees F.

Above 8000 Feet
Today, mostly cloudy skies with snow showers. Showers increasing in intensity in the afternoon. Snow accumulations up to 2 inches. Southwest winds at 20 to 30 mph, gusting to 40 mph. Daytime highs 17 to 27 degrees F. Tonight, mostly cloudy with scattered snow showers. Snow accumulation up to 1 inch. Lows 15 to 25 degrees F. West winds at 10 to 20 mph. Tuesday, mostly cloudy with scattered snow showers. Snow accumulation up to 1 inch. North winds at 15 to 25 mph. Daytime highs 18 to 28 degrees F.

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.