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 27, 2008 6:59 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.

A Pacific storm system has moved into the forecast area overnight. Snowfall began on the west side of the Sierra Crest and deposited several inches of new snow before snowfall accumulation began east of the Sierra Crest this morning. New snow amounts of 6 to 8 inches have been reported in the southern portion of the forecast area with 3 to 5 inches reported in the northern portion. Snowfall rates in excess of 1 inch per hour are expected until mid morning. After mid morning, snowfall rates are expected to decrease to less than 1 inch per hour along the Sierra Crest with lower snowfall rates occurring further to the east. The next round of high intensity snowfall is expected to begin tonight. Moderate to strong ridgetop winds have averaged from the southwest during the last 24 hours with a brief wind shift to the south observed for a few hours very early this morning.

Yesterday, moderate to strong ridgetop winds redistributed new snow causing wind loading and areas of snowpack instability. Along the Mt. Judah ridge (Donner Summit area), small natural avalanches (R1,D1) were observed in the most heavily wind loaded areas on NE-E aspect avalanche start zones. Crown heights ranged from 4 to 8 inches and measured 10 to 20 feet wide. Shooting cracks up to 10 feet long were observed around newly formed cornice features along the ridge. Small pockets of skier triggered sluffs were observed in steep open areas below mid slope. In the upper Deep Creek drainage (North of Squaw Peak), loud whumpfing was reported in an open meadow below treeline. Shooting cracks up to 15 feet long were reported in wind loaded areas just below the ridgeline. Skier triggered sluffs occurred in steep areas. No slab avalanche activity was observed in this area.

Today, a period of heavy new snowfall rates combined with southwest ridgetop winds will continue to wind load N-NE-E aspect avalanche start zones. The best window for natural avalanche activity is expected this morning before snowfall rates decrease as the day progresses. The threat of human triggered avalanches will remain throughout the day. Backcountry travelers should not be surprised today by the occurance of natural or human triggered avalanches that are 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. Natural avalanches are probable to likely in the most heavily wind loaded areas. Below treeline, human triggered avalanches are possible on steep slopes 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 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): 24 deg. F
Max. temperature at Sierra Crest past 24 hours: 29 deg. F
Average wind direction at Sierra Crest past 24 hours: Southwest
Average wind speed at Sierra Crest past 24 hours: 36 mph
Maximum wind gust at Sierra Crest past 24 hours: 102 mph
New snow fall at 8,200 feet past 24 hours: 3 to 8 inches
Total snow depth at 8,200 feet: 77 inches

Mountain Weather Forecast For Today:
Mostly cloudy with snow, greatest snowfall intensity during the morning hours.
Temperature forecast for 8,000 to 9,000 feet: 20 to 25 deg. F
Ridgetop winds forecast for the Sierra Crest: Southwest 50 to 60 mph with gusts to 85 mph.
Snowfall expected in the next 24 hours: 16 to 24 inches

2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, cloudy skies with snow. Snow accumulation 8 to 12 inches. Daytime highs 28 to 33 deg. F. Southwest winds at 15 to 20 mph with gusts to 30 mph, increasing to 20 to 30 mph with gusts to 45 mph in the afternoon.

Tonight, cloudy skies with snow. Snow accumulation 8 to 12 inches. Overnight lows 18 to 23 deg. F. Southwest winds at 25 to 35 mph with gusts to 65 mph.

For Monday, cloudy skies with snow in the morning. Snow showers likely in the afternoon. Snow accumulation 2 to 6 inches. Daytime highs 20 to 25 deg. F. Southwest winds at 20 to 30 mph with gusts to 45 mph, shifting to the west at 15 to 20 mph with gusts to 35 mph in the afternoon.

Above 8000 Feet:
Today, cloudy skies with snow. Snow accumulation 8 to 12 inches. Daytime highs 20 to 28 deg. F. Southwest winds at 25 to 40 mph, increasing to 40 to 55 mph with gusts to 80 mph in the afternoon.

Tonight, cloudy skies with snow. Snow accumulation 8 to 12 inches. Overnight lows 15 to 20 deg. F. Southwest winds at 40 to 60 mph with gusts to 90 mph.

For Monday, cloudy skies with snow in the morning. Snow showers likely in the afternoon. Snow accumulation 3 to 6 inches. Daytime highs 15 to 20 deg. F. West winds at 30 to 45 mph with gusts to 80 mph, decreasing to 65 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:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.