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 11, 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 LOW for all elevations and aspects. Some small roller ball/pinwheel and small isolated wet sluff activity may occur due to daytime warming. Normal caution is advised.

After a warm and wet day yesterday last night's low temperatures dropped back into the the low 20's. Warm air should move into the forecast area again today ahead of a small storm system. Air temperatures should be slightly higher than yesterday by early afternoon. The approaching storm system should bring clouds over the forecast area this afternoon and evening. This weak system has little moisture associated with it and should only bring a trace of new snow above 7000' tomorrow. The forecast calls for a high pressure system to start building over the forecast area after this storm.
Air temperatures warmed across the entire forecast area yesterday. Observations from this morning indicate that snowfall on the crest yesterday was isolated to very small areas. Most areas along the crest received mist and light rain even above 8000'. In the Mount Rose area no precipitation fell; however, the warm air temperatures helped make the dense new snow from the 9th even heavier. Last night's clear skies and cold temperatures should have allowed a solid refreeze to occur at all elevations in the forecast area causing the wet surface snow at all aspects below 8000' to freeze into hard surface crusts. Above 8000' the snow should still be heavy and snow surface should be a mix of wind affected surfaces, melt freeze crusts on the SE-S-SW aspects, and dense, heavy snow on the more N-NE aspects. Stability tests and other observations continue to indicate that the snowpack is gaining strength below the surface. On the actual snow surface observers reported some small human triggered roller-balls, pinwheels, and wet surface sluffs in the Maggies Peak and Echo Summit areas yesterday below 8000'. The warm air temperatures may create some wet surface instabilities again today. Due to the solid overnight refreeze, the forecast increase in afternoon cloud cover, the low sun angles, and shortness of daylight hours these wet instabilities should be limited to the surface layer of the snow and wet slab avalanche activity should be unlikely. These wet surface instabilities could form on most aspects below 8000' and would be most prevalent on the SE-S-SW-W aspects above 8000'.

Natural and human triggered slab avalanches are unlikely today. Some small wet surface instabilities like pinwheels, roller balls and small wet sluffs may occur today due to warm air temperatures. If the forecast cloud cover does not materialize or the temperatures climb higher than expected these instabilities would become more widespread. Remember LOW avalanche danger does not mean NO avalanche danger. The avalanche process does not simply turn off. Very, isolated pockets of instability may exist on any LOW danger day.

The bottom line: Avalanche danger is LOW for all elevations and aspects. Some small roller ball/pinwheel and small isolated wet sluff activity may occur due to daytime warming. Normal caution is advised.
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): 22 deg. F
Max. temperature at Sierra Crest past 24 hours: 32 deg. F
Average wind direction at Sierra Crest past 24 hours: West southwest
Average wind speed at Sierra Crest past 24 hours: 35 mph
Maximum wind gust at Sierra Crest past 24 hours: 54 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 60 inches
Mountain Weather Forecast For Today:
Clear skies this morning becoming increasingly cloudy over the course of the day.
Temperature forecast for 8,000 to 9,000 feet: 31 to 37 deg. F
Ridgetop winds forecast for the Sierra Crest: West at 10 to 20 mph with gusts to 30 mph.
Snowfall expected in the next 24 hours: trace
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, clear this morning becoming mostly cloudy this afternoon. Daytime highs 36 to 42 deg. F. West winds at 10 to 15 mph.

Tonight, mostly cloudy skies with overnight lows 22 to 26 deg. F. Southwest winds at 10 to 15 mph.

For Saturday, mostly cloudy skies with a chance of snow showers. Snow level around 7000'. Accumulation of less than an inch is expected. Daytime highs 33 to 39 deg. F. West winds at 10 to 15 mph.

Above 8000 Feet:
Today, clear this morning becoming mostly cloudy this afternoon. Daytime highs 31 to 37 deg. F. West winds at 10 to 20 mph with gusts to 30 mph.

Tonight, mostly cloudy skies with overnight lows 20 to 24 deg. F. West winds at 10 to 15 mph.

For Saturday, mostly cloudy skies with a chance of snow showers with accumulations of less than an inch expected. Daytime highs 30 to 36 deg. F. West winds at 10 to 15 mph shifting to the north with gusts to 30 mph by 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:
	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.