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.

A fast moving weather system passed through the forecast area last night. A quick 2 to 5 inches of new snow fell across the region with the greatest accumulations north of Lake Tahoe. Strong ridgetop winds accompanied the weather system with maximum ridgetop gusts up to 91 mph. Air temperatures fell with the cold front passage leaving air temperatures this morning above 8,000' in the upper teens and low 20s. Moderate southwest to west ridgetop winds will continue for today along with isolated snow showers in the afternoon and a second cold front passage and the possibility of a few more inches of snowfall tonight.

Observations:

Observations made yesterday on Castle Peak (Donner Summit area) revealed a better than expected snow surface refreeze from Tuesday night. The top 4 to 6 inches of the snow surface remained frozen into the afternoon hours. Moderate SW winds kept the snow surface from experiencing any significant melting in above treeline areas prior to 10:30 am. In near treeline and below treeline areas protected from the wind, the top 1 to 2 inches of the snow surface was melted in areas below 8,000' at around 11 am. With refreeze of the wet snow surface last night prior to the onset of snowfall, the existing snowpack is in good condition to handle new snow loading.

Avalanche concerns:

Avalanche concerns for today focus on new snow. In areas north of Lake Tahoe, new snow amounts of up to 5 inches will allow for shallow slabs in many areas and thicker slabs up to around 2 feet deep in heavily wind loaded areas. These slabs will likely be sensitive to human triggers today. From Lake Tahoe southward, 2 to 3 inches of new snow will really only present slab instability in wind loaded areas where some slabs may approach 1 foot deep. Across the forecast area today, the greatest areas of instability will exist in near and above treeline terrain on NW-N-NE-E aspects. Expect human triggered loose snow avalanche activity in steep wind protected areas below treeline in the northern portion of the forecast area as the melt freeze crust below the new snow will make for an efficient bed surface. Some isolated areas of warming instability may occur today in sun exposed areas below 7,500' if significant breaks in cloud cover occur.

The bottom line:

North of Lake Tahoe, avalanche danger is MODERATE in near and above treeline terrain on NW-N-NE-E aspects, 35 degrees and steeper. Below treeline avalanche danger is LOW with pockets of MODERATE danger in wind affected areas on NW-N-NE-E aspects 35 degrees and steeper. From Lake Tahoe southward, avalanche danger is LOW with pockets of MODERATE danger near and above treeline in wind loaded areas on NW-N-NE-E aspects 35 degrees and steeper. Below treeline avalanche danger is LOW.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	18 to 21 deg. F.
Max. temperature in the last 24 hours:	41 to 50 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:	91 mph
New snowfall in the last 24 hours:	2 to 5 inches
Total snow depth:	79 to 122 inches

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

For 7000-8000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Mostly cloudy skies with isolated snow showers in the afternoon.	Cloudy skies with scatter snow showers in the evening. Isolated snow showers after midnight.	Mostly cloudy skies.
Temperatures:	32 to 38 deg. F.	16 to 23 deg. F.	35 to 41 deg. F.
Wind direction:	W	W	W shifting to NW
Wind speed:	10 to 20 mph with gusts to 30 mph.	10 to 20 mph with gusts to 35 mph.	5 to 15 mph
Expected snowfall:	0 to trace in.	Up to 3 in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Mostly cloudy skies with isolated snow showers in the afternoon.	Cloudy skies with scatter snow showers in the evening. Isolated snow showers after midnight.	Mostly cloudy skies.
Temperatures:	23 to 31 deg. F.	15 to 21 deg. F.	28 to 36 deg. F.
Wind direction:	W	W	NW
Wind speed:	25 to 40 mph with gusts to 60 mph. Gusts decreasing to 45 mph in the afternoon.	20 to 30 mph with gusts to 40 mph.	15 to 25 mph with gusts to 40 mph.
Expected snowfall:	0 to trace in.	Up to 3 in.	O in.