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 Tuesday, April 10th, 2007 at 7:00 am

The bottom line: The avalanche danger is LOW across all elevations and aspects today. Low danger does not mean no danger, so continue to use safe backcountry travel techniques and to re-access snowpack conditions on a regular basis. Remember to be flexible and willing to change your plans when conditions change.

A colder air mass has moved into the forecast area. Overnight lows dropped into the low 20's, which is colder than they have been in over a week. Temperatures will continue to cool over the next few days as a cold low pressure system from the Gulf of Alaska moves into the forecast area starting tonight. This system is expected to bring waves of precipitation to the area through Thursday before it moves east, and the high pressure ridge rebuilds. By the time the precipitation starts, snow levels are forecasted to be around 5500' and should continue to drop during the storm. By Thursday there could be as much as a foot of new snow in the mountains. The winds should start shifting today and by tomorrow there should be moderate to strong southwest wind accompanying the storm.

Clear skies and overnight temperatures in the low 20's should have allowed the snowpack to undergo more refreezing last night. Today the melting part of the melt-freeze cycle should have a much less intense peak due to the solid overnight refreeze and cooler temperatures. Therefore, less water will be percolating through the snowpack causing bonds to dissolve between the snow grains. This diminished melting should result in less widespread wet snow instability that endures for less time today. The intense spring sun should still be able to cause some softening on the snow surface by this afternoon. The solar radiation should have the most impact on the E-SE-S-SW aspects that don't have much shade. Excellent corn snow conditions should form on these aspects by midday today. In areas that don't receive much sun the snow should stay firm for most of the day and continue to refreeze. Refreezing is a slow process and areas of unfrozen wet snow may remain in the top few feet of the snowpack into Wednesday.

Avalanche activity is unlikely today. However, there still may be a few isolated areas that have not refrozen enough to withstand today's sunshine. Some very small and very isolated areas of wet snow instability may develop in these areas by this afternoon. Continue to re-assess conditions regularly and use clues like surface instabilities and boot penetration to tell you when it is time to move off a slope.

With new snow and strong winds forecasted over the next two days, the avalanche danger will change in location and severity. Depending on how fast the snow surface refreezes before new snow starts accumulating on it, there may be an issue with how well the new snow bonds to the current surface. Tomorrow newly formed wind slabs could become an issue on aspects that have not needed much worry over the last week or two.

The bottom line: The avalanche danger is LOW across all elevations and aspects today. Low danger does not mean no danger, so continue to use safe backcountry travel techniques and to re-access snowpack conditions on a regular basis. Remember to be flexible and willing to change your plans when conditions change.

We will raffle a BCA backpack, beacon, shovel, and probe package on April 17th as a way to say thanks to everyone who has sent us a donation in the mail or via Pay Pal this season. All individuals who have donated $10 or more to SAC are automatically entered in this raffle. Thanks to all of our sponsors, the ski days, and everyone who has donated funding this winter, we have met our operating budget for this season and have a start on next year's funding. For more details about our financial situation please click here.

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:
41 deg. F
Average wind direction at Sierra Crest past 24 hours:
Westerly shifting to the northwest this morning
Average wind speed at Sierra Crest past 24 hours:
45 mph through midnight then it decreased to 20 mph
Maximum wind gust at Sierra Crest past 24 hours:
69 mph
New snow fall at 8,200 feet past 24 hours:
0
Total snow depth at 8,200 feet:
54 inches
Mountain Weather Forecast For Today:
Sunny and clear this morning then becoming partly cloudy by this evening.
Temperature forecast for 8,000 to 9,000 feet:
31 - 39 degrees F.
Ridgetop winds forecast for the Sierra Crest:
Westerly at 20 to 30 mph, decreasing to westerly at 10-15 mph with gusts to 30 mph in the afternoon.
Snowfall expected in the next 24 hours:
1-3 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, clear skies becoming partly cloudy by this evening with daytime highs 37 to 45 degrees F. Northwest winds at 10 to 15 mph, shifting to the west with gusts to 25 mph in the afternoon. Tonight, cloudy skies with a chance of snow increasing after midnight. Overnight lows around 26 degrees F. West winds at 10 to 20 mph. Tomorrow, snow likely with 1-4 inches of accumulation. Daytime highs 30 to 38 degrees F. Southwest winds at 20 to 30 mph with gusts to 40 mph are expected.

Above 8000 Feet:
Today, clear skies becoming partly cloudy by this evening with daytime highs 31 to 39 degrees F. West wind at 20 to 30 mph, decreasing to 10-15 mph with gusts to 30 mph in the afternoon. Tonight, cloudy skies with a chance of snow increasing after midnight. Overnight lows around 22 degrees F. West winds at 15 to 20 mph increasing to 20 to 30 mph with gusts to 50 mph after midnight. Tomorrow, snow likely with 3-5 inches of accumulation. Daytime highs 26 to 34 degrees F. Southwest winds at 25 to 40 mph with gusts to 60 mph are expected.

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