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 February 22, 2008 7:00 AM
Click here for a detailed map of the SAC forecast area

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Today's Advisory:

Avalanche danger is MODERATE near and above treeline on wind loaded NW-N-NE-E aspects, 35 degrees and steeper. Below treeline, avalanche danger is LOW with isolated pockets of MODERATE danger on wind loaded open slopes steeper than 38 degrees.

In the last 24 hours 7-9 inches of new snow fell north of Highway 50 and about 6 inches accumulated south of Highway 50. The southwest winds increased transporting snow and wind loading leeward slopes. The forecast calls for snow showers to decrease through tomorrow before the largest storm system reaches the forecast area on Saturday afternoon. Snow levels should stay close to 5000' until the onset of Saturday's storm when warm subtropical air and moisture should bring snow levels up. The southwest winds should remain strong enough to transport snow and should increase as Saturday's system approaches.

A total of 10 to 16 inches of snow has fallen over the forecast area since early Wednesday morning. This snow fell on a strong, well consolidated snowpack whose surface was a mix of hard wind packed surfaces, melt-freeze crusts, and some unconsolidated snow. Observations on Jake's Peak Wednesday indicated that the new snow had not bonded well to these surfaces. Yesterday at Waterhouse Peak and Incline Lake Peak observations showed that this interface had gained some strength, but that the bonding process was slower than usual. As the winds increased across the forecast area yesterday afternoon wind loading started to form wind slabs on leeward slopes near and above treeline. These slabs remained small but started to crack under a person's weight by late afternoon on Waterhouse Peak. The combination of more new snow, more wind, and the relatively weak interface between the old snow surfaces and the new snow should cause human triggerable wind slabs to become larger and more widespread today.

The possibility of natural avalanche activity resulting from wind loading and new snow should decrease quickly and should be unlikely for most of the day. Natural avalanches are not impossible and could still occur in very isolated pockets on the most heavily wind loaded areas or in response to cornice failures. Human triggered avalanches that fail at the old/new snow interface will be possible today in wind loaded areas on steep NW-N-NE-E aspects near and above treeline. Below treeline today slab formation is not expected due low density new snow and modest winds making most avalanche activity unlikely. However, some small isolated human triggerable slabs could form below treeline on steep, open, wind loaded slopes as the winds increase.

The bottom line: Avalanche danger is MODERATE near and above treeline on wind loaded NW-N-NE-E aspects, 35 degrees and steeper. Below treeline, avalanche danger is LOW with isolated pockets of MODERATE danger on wind loaded open slopes steeper than 38 degrees.

Please send us your snow, weather, and avalanche observations by clicking the submit observations link on our contact page.

Andy Anderson, Avalanche Forecaster

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: 25 deg. F.
Average wind direction at Sierra Crest past 24 hours: Southwest
Average wind speed at Sierra Crest past 24 hours: 30-35 mph
Maximum wind gust at Sierra Crest past 24 hours: 70 mph
New snow fall at 8,200 feet past 24 hours: 8 inches
Total snow depth at 8,200 feet: 88 inches
Mountain Weather Forecast For Today:
Snow showers throughout the day.
Temperature forecast for 8,000 to 9,000 feet: 22 to 28 deg. F
Ridgetop winds forecast for the Sierra Crest: Southwest at 25 to 35 mph with gusts to 65 mph
Snowfall expected in the next 24 hours: 4 to 8 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, snow showers that should taper off some in the afternoon. Snow accumulation 1 to 4 inches. Daytime highs around 30 deg. F. Southwest winds at 15 to 20 mph with gusts to 35 mph.

Tonight, mostly cloudy skies with scattered snow showers. Snow accumulation up to 2 inches. Overnight lows around 16 deg. F. Southwest winds at 15 to 20 mph with gusts to 35 mph.

For Saturday, cloudy skies with snow in the afternoon. Snow accumulation up to 2 inches. Daytime highs around 34 deg. F. Southwest winds at 20 to 30 mph with gusts to 50 mph.

Above 8000 Feet:
Today, snow showers that should taper off some in the afternoon. Snow accumulation 2 to 6 inches. Daytime highs 22 to 28 deg. F. Southwest winds at 25 to 35 mph with gusts to 65 mph.

Tonight, mostly cloudy skies with scattered snow showers. Snow accumulation up to 2 inches. Overnight lows around 14 deg. F. Southwest winds at 10 to 20 mph with gusts to 45 mph.

For Saturday, cloudy skies with snow in the afternoon. Snow accumulation up to 2 inches. Daytime highs around 31 deg. F. Southwest winds at 20 to 40 mph with gusts to 70 mph.

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.