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.

2-3 inches of new, heavy, wet snow fell along the Sierra Crest above 7500 ft. yesterday. Snow levels fluctuated greatly, and much of the precipitation that fell below 7500 ft fell as rain. East of Lake Tahoe less precipitation occurred, and only 1-2 inches of snow accumulated. After a period of sunnier weather this morning, a weak low pressure system should bring some clouds, continued southwest winds, and slightly cooler temperatures into the region. Today's highs in the mid 30's should occur this morning. Temperatures should fall steadily in the afternoon as the system arrives. The precipitation associated with this system should stay north of the area. Another weak system should impact the forecast area tomorrow afternoon and evening with similar results.

Observations:

In the northern part of the forecast area on Andesite Ridge and in the Mt. Lola region, snowfall started around 1 pm yesterday. Many areas received a mix of rain and snow due to changing snow levels. In both of these areas, snowpits showed dense wind slabs sitting on top of lighter snow. Stability tests on the interface between these layers showed mostly stable results (snowpit from Andesite, snowpit from Lola). Some ski cuts on steep tree-well slopes did cause small fractures on those slopes on Andesite Ridge. On Mt. Lola snowmobile cuts on wind-loaded test slopes both above and below treeline did not show any signs of instability. In both of these areas a crust existed on most aspects up to 8000 ft. This crust would support a skier or snowmobiler in most locations. This crust did not exist on shaded northerly aspects above 8000 ft in the Mt. Lola area (more info).

Avalanche Concern #1: Wind Slabs

Near and above treeline the strong southwest winds will have created wind slabs on the leeward aspects. Due to the small amount of new snow that fell yesterday, most of these new wind slabs should remain relatively small (6-12 inches). In the most wind-loaded areas some thicker slabs could exist. These slabs will rest on top of firm snow that could serve as good bed surfaces for the new slabs to slide on. Human triggering of these new wind slabs will remain possible today in steep wind-loaded areas. Even though these slabs may be small they could still have serious consequences. The wind-loaded N-NE-E and cross-loaded NW and SE aspects along the Sierra Crest will hold the largest and most fragile wind slabs. Areas east of Lake Tahoe and near Bear Valley that received less snow will hold less and smaller wind slabs.

Avalanche Concern #2: Warming instabilities

Cooling daytime temperatures, an increase in cloud cover, and continued strong winds should prevent dangerous instabilities due to daytime warming from forming today. Some small roller ball activity or small point releases could occur as the sun hits the new snow this morning. If more sunshine and warming occurs than forecasted, these instabilities will become more widespread and larger.

The bottom line:

Near and above treeline, avalanche danger is LOW with pockets of MODERATE danger on NW-N-NE-E-SE aspects on slopes 35 degrees and steeper. Below treeline LOW avalanche danger exists on all aspects. If more sunshine and daytime warming than forecasted occurs today, the avalanche danger will increase on sun-exposed aspects at all elevations.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

Weather Observations from along the Sierra Crest between 8200 ft and 8800 ft:

0600 temperature:	22-30 deg. F.
Max. temperature in the last 24 hours:	33-40 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	45 mph
Maximum wind gust in the last 24 hours:	106 mph
New snowfall in the last 24 hours:	above 7500 ft: 2-3 inches
Total snow depth:	93-130 inches

Two-Day Mountain Weather Forecast - Produced in partnership with the Reno NWS

For 7000-8000 ft:
	Friday:	Friday Night:	Saturday:
Weather:	Partly cloudy this morning becoming mostly cloudy this afternoon.	Mostly cloudy	Mostly cloudy
Temperatures:	34-38 deg. F.	20-28 deg. F.	34-38 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	10-20 mph with gusts to 30 mph	10-20 mph with gusts to 30 mph	15-20 mph with gusts to 35 mph
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Friday:	Friday Night:	Saturday:
Weather:	Partly cloudy this morning becoming mostly cloudy in the afternoon. Temperatures falling during the day.	Mostly cloudy	Mostly cloudy
Temperatures:	28-34 deg. F.	23-28 deg. F.	26-32 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	20-30 mph with gusts to 50 mph	20-30 mph with gusts to 50 mph	20-30 mph with gusts to 50 mph
Expected snowfall:	O in.	O in.	O in.