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 28, 2008 7:04 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 CONSIDERABLE with pockets of HIGH danger on heavily wind loaded N-NE-E aspects, 37 degrees and steeper. Below treeline, avalanche danger is LOW with pockets of MODERATE danger in wind affected areas, 37 degrees and steeper.

The latest wave of the Pacific storm system affecting the forecast area has moved off to the east. Cold air and continued snow showers remain over the region. Ski area snow study plots and remote sensors are reporting 24 hour new snow accumulation of 12 to 20 inches at 15 to 18% density along the Sierra Crest. Around 10 to 15 inches of new snow has accumulated in the Mount Rose area. This brings the storm totals up to 20 to 30 inches since Saturday afternoon. Strong southwest ridgetop winds gusting well over 100 mph have been observed over the Sierra Crest for the past 24 hours, with gusts to 85 mph reported in the Mount Rose area. Strong ridgetop winds are expected to continue this morning before decreasing to moderate speed and shifting to the west this afternoon. Snow showers are expected to continue until late this afternoon. Mountain top air temperatures in the single digits and low teens are expected to hold through this evening before warmer air moves in after midnight, as the next storm system approaches the area.

Yesterday, strong ridgetop winds caused loading of new snow to occur in the lower portion of avalanche start zones in most areas. Very little new cornice formation was observed. On Tamarack Peak (Mount Rose area), fairly stable snowpack conditions were observed above and below treeline on N-NE-E aspects. On Mt. Ralston (Echo Summit area), shooting cracks up to 15 feet long were skier triggered below treeline on SSE and E aspects. In more open areas below treeline with greater wind affect, no obvious signs of instability were reported. On Carson Pass, a natural avalanche was reported to have occurred on a NE aspect just to the east of the pass summit, depositing 4 to 6 feet of snow on the highway. No other information was reported regarding this avalanche. Very heavy wind loading was reported in the area.

As the current storm system winds down, the best window for natural avalanche activity to occur has past. However, southwest to west ridgetop winds will continue to move snow and wind load N-NE-E aspect avalanche start zones. Higher density new snow has been deposited over lower density new snow, creating upside down layer conditions within the top 4 feet of the snowpack. The threat of large human triggered avalanches will remain throughout the day. Backcountry travelers should not be surprised by a human triggered avalanche that is large enough to bury, injure, or kill a person. Near and above treeline, human triggered avalanches are likely today on N-NE-E aspects in steep wind loaded areas. Isolated natural avalanches remain possible in the most heavily wind loaded areas. Below treeline, human triggered avalanches are possible on steep slopes in the most heavily wind affected areas.

The bottom line: Near and above treeline, avalanche danger is CONSIDERABLE with pockets of HIGH danger on heavily wind loaded N-NE-E aspects, 37 degrees and steeper. Below treeline, avalanche danger is LOW with pockets of MODERATE 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): 7 deg. F
Max. temperature at Sierra Crest past 24 hours: 23 deg. F
Average wind direction at Sierra Crest past 24 hours: Southwest
Average wind speed at Sierra Crest past 24 hours: 69 mph
Maximum wind gust at Sierra Crest past 24 hours: 144 mph
New snow fall at 8,200 feet past 24 hours: 12 to 20 inches
Total snow depth at 8,200 feet: 77 inches

Mountain Weather Forecast For Today:
Mostly cloudy with snow showers.
Temperature forecast for 8,000 to 9,000 feet: 5 to 15 deg. F
Ridgetop winds forecast for the Sierra Crest: West 40 to 60 mph with gusts to 80 mph, decreasing in the afternoon.
Snowfall expected in the next 24 hours: 3 to 6 inches

2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, mostly cloudy skies with snow showers. Snow accumulation up to 6 inches. Daytime highs 15 to 22 deg. F. West winds at 20 to 30 mph with gusts to 45 mph, decreasing to 15 to 20 mph with gusts to 30 mph in the afternoon.

Tonight, cloudy skies with overnight lows 9 to 14 deg. F., warming to 14 to 19 deg. F. after midnight. West winds at 10 to 20 mph with gusts to 30 mph.

For Tuesday, cloudy skies with a chance of snow showers. Snow accumulation up to 6 inches. Daytime highs 20 to 25 deg. F. West winds at 15 to 20 mph with gusts to 35 mph, shifting to the southwest at 20 to 30 mph with gusts to 50 mph in the afternoon.

Above 8000 Feet:
Today, mostly cloudy skies with snow showers. Snow accumulation 3 to 6 inches. Daytime highs 5 to 15 deg. F. West winds at 40 to 60 mph with gusts to 80 mph, decreasing to 35 to 45 mph with gusts to 60 mph in the afternoon.

Tonight, mostly cloudy skies with overnight lows 5 to 10 deg. F., warming to 10 to 15 deg. F. after midnight. West winds at 20 to 35 mph with gusts to 50 mph.

For Tuesday, cloudy skies with a chance of snow showers. Snow accumulation up to 6 inches. Daytime highs 15 to 20 deg. F. West winds at 30 to 40 mph with gusts to 55 mph, increasing to 40 to 50 mph with gust to 75 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:
	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.