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 January 26, 2008 7:00 AM
Click here for a detailed map of the SAC forecast area

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Today's Advisory:

Near and above treeline, avalanche danger is MODERATE with pockets of CONSIDERABLE danger on heavily wind loaded N-NE-E aspects, 37 degrees and steeper. Below treeline, avalanche danger is LOW with pockets of MODERATE avalanche danger in wind affected areas, 37 degrees and steeper.

A break in the weather will occur today with periods of sun mixed with scattered snow showers over the higher elevations. A larger and warmer Pacific storm system is expected to impact the forecast area beginning this evening. South winds over the forecast area increased yesterday during the afternoon hours and were sufficient to cause wind transport of snow. Ridgetop winds have shifted to southwest during the overnight hours and have continued to increase in speed ahead of the approaching storm system. Air temperatures have warmed several degrees over the past 24 hours.

Yesterday, increasing winds redistributed low density snow that fell over the past week, increasing slab formation in wind loaded and wind affected areas. On Mt.Tallac (Desolation Wilderness area), shooting cracks were observed in wind loaded areas below treeline on the northeast ridge. Near and above treeline, significant wind loading and slab formation was observed on north aspects. A very small skier triggered avalanche was observed at 8,500' on a wind affected, 39 degree, NE aspect gully feature, involving only the top 4 inches of the snowpack. Along the ridge north of Galena Creek (Mount Rose area), an isolated whumpf and increasing slab formation were reported. Around 1 to 5 inches of new snow fell across the forecast area yesterday afternoon and evening, with the greatest accumulations observed north of Lake Tahoe. This morning, the snow study plot at Sugar Bowl is reporting 5 inches of new snow with a density of 8%.

Today, southwest ridgetop winds will continue to redistribute snow onto N-NE-E aspect avalanche start zones. As a result, recently formed slabs will continue to increase in size. In many areas, these slabs sit on top of lower density snow from the past week, enhancing the hardness difference at the layer interface at the bottom of the slab. This difference is easily felt by probing the snow. Near and above treeline, human triggered avalanches are possible to probable today on N-NE-E aspects in steep wind loaded areas. Natural avalanches are possible in the most heavily wind loaded areas. Below treeline, human triggered avalanches are possible in the most heavily wind affected areas. In areas not affected by wind, natural and human triggered avalanches are unlikely.

The bottom line: Near and above treeline, avalanche danger is MODERATE with pockets of CONSIDERABLE danger on heavily wind loaded N-NE-E aspects, 37 degrees and steeper. Below treeline, avalanche danger is LOW with pockets of MODERATE avalanche danger in wind affected areas, 37 degrees and steeper.

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

Brandon Schwartz, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 21 deg. F
Max. temperature at Sierra Crest past 24 hours: 24 deg. F
Average wind direction at Sierra Crest past 24 hours: South, shifting to southwest
Average wind speed at Sierra Crest past 24 hours: 24 mph
Maximum wind gust at Sierra Crest past 24 hours: 65 mph
New snow fall at 8,200 feet past 24 hours: 1 to 5 inches
Total snow depth at 8,200 feet: 74 inches

Mountain Weather Forecast For Today:
Mostly cloudy with scattered snow showers.
Temperature forecast for 8,000 to 9,000 feet: 23 to 30 deg. F
Ridgetop winds forecast for the Sierra Crest: Southwest 30 to 45 mph with gusts to 70 mph.
Snowfall expected in the next 24 hours: 5 to 10 inches, mainly overnight tonight

2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, mostly cloudy with scattered snow showers. Daytime highs 30 to 35 deg. F. South winds at 10 to 20 mph with gusts to 30 mph.

Tonight, cloudy skies with snow. Snow accumulation 4 to 8 inches. Overnight lows 22 to 27 deg. F. South winds at 10 to 20 mph with gusts to 30 mph.

For Sunday, cloudy skies with heavy snowfall. Snow accumulation 12 to 18 inches. Daytime highs 26 to 31 deg. F. Southwest winds at 10 to 20 mph with gusts to 30 mph, increasing to 20 to 30 mph with gusts to 45 mph in the afternoon.

Above 8000 Feet:
Today, mostly cloudy with scattered snow showers. Daytime highs 23 to 33 deg. F. Southwest winds at 30 to 45 mph with gusts to 70 mph.

Tonight, cloudy skies with snow. Snow accumulation 5 to 10 inches. Overnight lows 20 to 25 deg. F. South winds at 30 to 45 mph with gusts to 70 mph.

For Sunday, cloudy skies with heavy snowfall. Snow accumulation 15 to 20 inches. Daytime highs 23 to 28 deg. F. Southwest winds at 30 to 40 mph with gusts to 65 mph, increasing to 40 to 55 mph with gusts to 80 mph in the afternoon.

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