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 Thursday, March 29th, 2007 at 7:00 am

The bottom line: Near and above treeline, avalanche danger is MODERATE on wind loaded SW-W-NW aspects 35 degrees and steeper. On sun exposed S-SW-W slopes steeper than 35 degrees the avalanche danger will rise to MODERATE for wet snow instabilities as daytime warming occurs. Below treeline, avalanche danger will become MODERATE in sun exposed areas, 35 degrees and steeper as daytime warming occurs.

A high pressure ridge has built back over the area and should bring much warmer temperatures and slightly calmer winds at all elevations today. The strong east winds that continued through last night should begin to decrease this afternoon. By tomorrow the winds should be light and temperatures should continue to climb. This ridge should remain in place for the next few days allowing a return to clear, warm weather. A few small weak systems passing to the north of the forecast area may bring some clouds and a shift in wind direction over the weekend.

There are two main avalanche concerns for today. The first is a result of the strong ridgetop easterly winds that have been blowing ever since the storm ended. These winds have stripped most of the new snow from the traditional N-NE-E aspect starting zones and redepositted it onto the NW-W-SW aspects. On slopes that still had snow cover before the storm, these newly formed stiff windslabs and cornices were deposited on an old snow surface had already refrozen and may not have bonded well at this interface. The subtle changes in wind speed and direction during the last 2 days will also create some suspect interfaces within those newly formed windslabs. These windslabs should be reactive today and it could be possible for humans to cause them to fail. Use clues like cornices, drifted snow, ripples, and blowing snow to determine where new windloading has occured and be very cautious around these areas.

The other avalanche concern today stems from the rapid warming predicted for today. Air temperatures are forecasted to be 8-10 degrees warmer today than what was observed yesterday. These warmer air temperatures, intense solar radiation, and calming winds will all contribute to wet snow instabilities forming on sun exposed slopes today. The new snow that has been deposited in cross loaded SE-S aspects and windloaded SW-W aspects will be most prone to warming instability today. However, any areas that are protected from NE-E winds and receive large amounts of solar radiation will be suspect. Expect to see rollerball and pinwheel activity on these aspects today. Human triggered slabs are also possible in these areas on slopes steeper than 35 degrees today.

The bottom line: Near and above treeline, avalanche danger is MODERATE on wind loaded SW-W-NW aspects 35 degrees and steeper. On sun exposed S-SW-W slopes steeper than 35 degrees the avalanche danger will rise to MODERATE for wet snow instabilities as daytime warming occurs. Below treeline, avalanche danger will become MODERATE in sun exposed areas, 35 degrees and steeper as daytime warming occurs.

SAC is very grateful of everyone who was involved in the SAC Ski Day fundraiser at Sugar Bowl. With the financial support of everyone who purchased SAC lift tickets and the organizational and marketing support of those who made the event possible, we were able to raise just over $10,000 for our operating budget. This will allow us to finish operations this spring and have funding for operations during the first two months of next winter. Thank you to all contributors, Sugar Bowl Ski Area, and Snowbomb.com!

Andy Anderson, Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
21 deg. F
Max. temperature at Sierra Crest past 24 hours:
31 deg. F
Average wind direction at Sierra Crest past 24 hours:
Easterly
Average wind speed at Sierra Crest past 24 hours:
50 mph
Maximum wind gust at Sierra Crest past 24 hours:
74 mph
New snow fall at 8,200 feet past 24 hours:
0 inches
Total snow depth at 8,200 feet:
73 inches
Mountain Weather Forecast For Today:
Sunny skies.
Temperature forecast for 8,000 to 9,000 feet:
39 to 45 degrees F.
Ridgetop winds forecast for the Sierra Crest:
Easterly at 35-50 mph with gusts to 60 mph diminishing to northeasterly at 15-30 mph by this afternoon.
Snowfall expected in the next 24 hours:
0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, sunny skies with daytime highs 42 to 48 degrees F. Northeast winds at 10 to 20 mph. Tonight, clear skies with overnight lows around 32 degrees F. East winds at 10 mph. Tomorrow, partly cloudy with daytime highs 45 to 53 degrees F. East winds at 10 mph, shifting to the northwest at 10-15 mph in the afternoon.

Above 8000 Feet:
Today, sunny skies with daytime highs 39 to 45 degrees F. East winds at 35-50 mph with gusts to 60 mph diminishing to northeast winds at 15-30 mph by this afternoon. Tonight, clear skies with overnight lows 28 to 32 degrees F. Northeast winds at 10-20 mph. Tomorrow, partly cloudy with daytime highs 40 to 47 degrees F. Northwest winds at 10-20 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:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.