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 March 19, 2008 7:00 AM

A map of the SAC forecast area is available on our home page.

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Today's Advisory:
The avalanche danger is LOW at all elevations and aspects. Isolated pockets of MODERATE danger could develop below treeline on open SE-S-SW-W slopes steeper than 40 degrees due to daytime warming. If any slopes receive rain today the avalanche hazard on those slopes will increase.

Cooler temperatures, strong southwest winds, more cloud cover, and scattered snow showers should impact the forecast area today and tomorrow as a low pressure system moves across northern CA and the Pacific Northwest. Snow levels should start high and should drop below 6500 ft overnight. This system has little moisture associated with it and accumulations should be light with only 2 to 3 inches expected in the mountains over the next 24 hours.

Yesterday more large natural point release avalanches occurred near and above treeline on the SE aspects of Slide Mountain (Mount Rose area), above and below treeline on SE-S-SW aspects of Talking Mountain (Echo summit), and on the SE aspects of Mt. Tallac above and below treeline. These point release slides entrained the top 4 to 6 inches of new snow and ran for 400 to 800 ft. They occurred as free water saturated the new snow layer and dissolved any bonds that held the layer to itself and the old snow. Overnight cooler temperatures and some radiational cooling of the snow pack should have allowed this wet surface snow to refreeze and gain strength. Observations from across the forecast area show that the new snow continues to settle, consolidate, and bond to the old snow surfaces on all aspects.

Much cooler temperatures, increased cloud cover, an overnight refreeze, and 2 days of a melt/freeze cycle should prevent the wet snow instabilities that formed over the last two days from becoming widespread again today. Some areas below treeline where the forecast calls for temperatures to reach the low 40's could see human triggerable wet snow instabilities as the day warms up. Southerly slopes that are exposed to the sun this morning and through midday would be the most suspect. The other concern would be any rain that falls on the snow today. The rain adds weight to the snowpack, dissolves the bonds between the snow grains, and lubricates bed surfaces. The northerly aspects that have not undergone as much melting and refreezing would be especially prone to failures due to rain on snow, but the avalanche hazard will increase on any slopes that receive rain today.

The bottom line: The avalanche danger is LOW at all elevations and aspects. Isolated pockets of MODERATE danger could develop below treeline on open SE-S-SW-W slopes steeper than 40 degrees due to daytime warming. If any slopes receive rain today the avalanche hazard on those slopes will increase.
Public donations to the avalanche center this season are below our fundraising goal. We are going to raffle a beacon, shovel, probe, and backpack package as a way give back to those who donate $100 or more before March 30th. For more information on the raffle and amount of donations received click here.

Andy Anderson, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 28 deg. F
Max. temperature at Sierra Crest past 24 hours: 40 to 47 deg. F.
Average wind direction at Sierra Crest past 24 hours: Southwest
Average wind speed at Sierra Crest past 24 hours: 25 mph
Maximum wind gust at Sierra Crest past 24 hours: 51 mph
New snowfall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 84 inches
Mountain Weather Forecast For Today:
Mostly sunny this morning becoming mostly cloudy by midday as isolated snow showers develop.
Temperature forecast for 8,000 to 9,000 feet: 30 to 36 deg. F
Ridgetop winds forecast for the Sierra Crest: Southwest at 15 to 25 mph with gusts to 45 mph in the morning then increasing to 25 to 35 mph with gusts to 60 mph in the afternoon.
Snowfall expected in the next 24 hours: 2 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, mostly sunny this morning becoming mostly cloudy by midday as isolated snow showers develop. Daytime highs 36 to 42 deg. F. Winds out of the southwest at 10 to 20 mph with gusts to 30 mph in the morning then increasing to 20 to 30 mph with gusts to 45 mph in the afternoon.

Tonight, mostly cloudy skies with scattered snow showers and accumulations up to 2 inches. Overnight lows 20 to 25 deg. F. West winds at 20 to 30 mph with gusts to 45 mph decreasing to 10 to 20 mph after midnight.

For Thursday, partly cloudy skies with a chance of isolated snow showers in the morning. Daytime highs 32 to 38 deg. F. West winds at 10 to 20 mph with gusts to 30 mph.

Above 8000 Feet:
Today, mostly sunny this morning becoming mostly cloudy by midday as isolated snow showers develop. Daytime highs 30 to 36 deg. F. Winds out of the southwest at 15 to 25 mph with gusts to 45 mph in the morning then increasing to 25 to 35 mph with gusts to 60 mph in the afternoon.

Tonight, mostly cloudy skies with scattered snow showers and accumulations up to 2 inches. Overnight lows 18 to 23 deg. F. West winds at 25 to 40 mph with gusts to 70 mph.

For Thursday, partly cloudy skies with a chance of isolated snow showers in the morning. Daytime highs 27 to 32 deg. F. West winds at 15 to 30 mph with gusts to 55 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:
	Wednesday:	Wednesday Night:	Thursday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.