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 Sunday, March 25th, 2007 at 7:00 am

At this time, SAC is still short $1,700 in operating funds for this season and we have no money with which to start next season. Today is our Ski Day at Sugar Bowl. We hope to see you there for wonderful day of spring sun on the deck, corn snow on the slopes, and a gear raffle from Backcountry Access, Black Diamond, and Patagonia. We are very appreciative of the financial support already received this winter from a variety of users. If you have not yet shown your financial support for us this winter, please do so!

The bottom line: Avalanche danger is LOW for all elevations and aspects. As daytime warming occurs a few small, isolated pockets of MODERATE avalanche danger may develop on SW-S-SE-E slopes 35 degrees and steeper that are exposed to the sun today in the form of wet snow instabilities.

Today's high temperatures should be similar to yesterday's. This warmth will be offset by an increase in wind speed and cloud cover as the high pressure begins to be replaced by a weak cold front that is the precursor to a colder storm system predicted to arrive over the forecast area on Monday. The winds have already shifted to the southwest and should continue to increase in intensity through Monday. If it does not split too much, this colder system should have enough moisture associated with it to bring 6-12 inches of snow to the mountains. Some snow should accumulate at lake level as the storm cools off by Tuesday morning. A few days of cold weather should follow this storm.

Last night temperatures were slightly cooler, but they still stayed above freezing in many areas along the Sierra Crest. The Mount Rose area did manage get down to 31 degrees F last night. These cooler temps along with the mostly clear skies allowed the snowpack to refreeze some due to radiational cooling. Warm temperatures and patchy sunshine forecast for today should begin to soften the snow early in the day. These warm temperatures are nothing new. After last week's extended period of unseasonable warm temperatures, water percolation channels are well developed through the snowpack in most areas. These channels should help prevent widespread pooling of water at layer interfaces within the snowpack: a process that can weaken the snowpack greatly. The prolonged melt-freeze cycles have also allowed the snowpack to become more uniform. This trend promotes increasing stability over the long term. In the short term snowpack stability goes through daily oscillations during the melt freeze cycles. Instability peaks shortly after the peak of the melting phase of the melt-freeze cycle when the most water is present in the snowpack. The peak of today's melt-freeze cycle should have a less intense effect on stability than last week due to more gradual warming, slightly lower high temperatures, stronger refreezes earlier this week, more cloud cover, and those more developed percolation channels. Therefore the chance of wet snow instabilities should be less widespread and severe.

Any wet snow instabilities that do develop in response to daytime warming today should be limited to surface instabilities like pinwheels, roller-balls, and maybe a small wet loose sluff on SW-S-SE-E aspects on slopes steeper than 35 degrees that are exposed to the sun today. Natural wet slab avalanches are unlikely today but not impossible. Areas around glide cracks and in places where the snowpack is sitting on an impermeable ground surface like bedrock would be the most likely to produce one of the rare wet slabs.

As the day warms up good corn conditions should develop quickly on the sun exposed SW-S-SE-E aspects across the forecast area. This corn should happen early today and quickly become sloppy, wet, punchy, and less stable by the afternoon. Remember to continually evaluate the conditions as they change over the course of the day and be willing to change plans accordingly. A good test for wet snow instability potential is to step off your equipment and check boot penetration in the snowpack. If boot penetration exceeds boot tops in wet snow, it is time to move away from that slope and slopes like it.

The bottom line: Avalanche danger is LOW for all elevations and aspects. As daytime warming occurs a few small, isolated pockets of MODERATE avalanche danger may develop on SW-S-SE-E slopes 35 degrees and steeper that are exposed to the sun today in the form of wet snow instabilities.

Andy Anderson , Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
34 deg. F
Max. temperature at Sierra Crest past 24 hours:
51 deg. F
Average wind direction at Sierra Crest past 24 hours:
Southwesterly
Average wind speed at Sierra Crest past 24 hours:
25-30 mph
Maximum wind gust at Sierra Crest past 24 hours:
42 mph
New snow fall at 8,200 feet past 24 hours:
0 inches
Total snow depth at 8,200 feet:
63 inches
Mountain Weather Forecast For Today:
Warm with increasing clouds and southwest wind throughout the day.
Temperature forecast for 8,000 to 9,000 feet:
42 to 47 degrees F.
Ridgetop winds forecast for the Sierra Crest:
Southwest at 25-35 mph with gusts to 60 mph in the afternoon.
Snowfall expected in the next 24 hours:
0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, partly cloudy skies with daytime highs 47 to 54 degrees F. Southwest winds at 15 to 20 mph gusts to 35 mph. Tonight, mostly cloudy skies with overnight lows 33 to 38 degrees F. Southwest winds at 15 to 25 mph with gusts to 35 mph. Tomorrow, snow with accumulations of 4 to 6 inches. Daytime highs 36 to 41 degrees F dropping to 32 degrees F by the afternoon. Southwest winds at 20 to 35 mph with gusts to 45 mph are expected.

Above 8000 Feet:
Today, partly cloudy skies with daytime highs 42 to 47 degrees F. Southwest winds at 25 to 35 mph gusts to 60 mph. Tonight, mostly cloudy skies with overnight lows 28 to 33 degrees F. Southwest winds at 25 to 35 mph with gusts to 60 mph. Tomorrow, snow with accumulations of 4 to 6 inches. Daytime highs 31 to 36 degrees F dropping to into the upper 20's by the afternoon. Southwest winds at 30 to 40 mph with gusts to 80 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:
	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.