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.

High pressure is moving out of the forecast area ahead of an approaching low pressure system. Transitional weather with colder air temperatures and light to moderate speed winds under sunny skies is expected for today. Remote sensors are reporting air temperatures above 8,000' in the mid teens to mid 20s this morning. This is about 5 to 10 degrees colder than what was observed 24 hours ago. Southwest winds that were moderate to strong in speed yesterday have decreased overnight. Light to moderate speed winds out of the west this morning are forecast to shift to the south this afternoon. Winds are forecast to become strong in speed out of the southwest tonight a continue through tomorrow. Cloud cover will begin to increase tonight with snowfall expected tomorrow afternoon. New snow amounts of 6 or more inches are possible late Thursday into Friday.

Recent Observations:

Observations made yesterday on Castle Peak (Donner Summit area) and on Porcupine Ridge (Luther Pass area) matched well with other recent observations from around the forecast area. Faceting processes are at work in the top 1 foot or so of the snowpack on many NW-N-NE-E aspects above 7,200'. Near crust facets are fairly weak, but snowpit tests indicate that propagation is unlikely upon weak layer collapse in most areas. Isolated areas along the eastern boundary of the forecast area have shown an overall shallow snowpack with weaker December facets that hold the ability to propagate. Collapse of this December weak layer has proven very difficult to trigger. These weak layers are not an instability issue for today, but warrant monitoring during future snow loading events (pit profiles, photos, videos, more info).

Around the forecast area, snow surface conditions on N-NE aspects consist of 0.5 to 2 inches of dry, lightly faceted recent storm snow on top of supportable rain crust in near and below treeline areas with protection from NE winds. Areas with exposure to NE winds are scoured down to the most recent rain crust. Melt-freeze conditions are well established on SE-S-SW aspects. E and W aspects hold a mix of melt-freeze and dry snow conditions.

Avalanche Concerns:

Natural and human triggered avalanches remain unlikely today. Around an inch or so of wet surface snow formation is expected on SE-S-SW aspects in response to daytime warming. Colder air temperatures this morning and colder forecast maximum daytime air temperatures as compared to the past few days will reduce the overall amount and delay the onset of wet snow formation today. Any form of wet snow instability is unlikely today. Other aspects are expected to remain frozen all day with widespread supportable crust conditions.

Triggering of slab avalanches on layers of near crust faceted crystals that have been noted in recent observations remains unlikely at this time. This is due to a lack of a significant overlying slab for weak layers close to the snow surface and due to the strength of the overlying slab preventing collapse of more deeply buried weak layers.

The bottom line:

Avalanche danger remains LOW for all elevations and aspects. Normal caution is advised.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	16 to 26 deg. F.
Max. temperature in the last 24 hours:	32 to 40 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	25 mph
Maximum wind gust in the last 24 hours:	59 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	54 to 81 inches

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

For 7000-8000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Sunny skies.	Partly cloudy skies.	Cloudy skies with a chance of snow showers in the afternoon.
Temperatures:	33 to 40 deg. F.	16 to 23 deg. F.	30 to 36 deg. F.
Wind direction:	W	SW	SW
Wind speed:	Around 10 mph.	15 to 25 mph with gusts to 45 mph.	20 to 30 mph with gusts to 50 mph. Gusts decreasing to 40 mph in the afternoon.
Expected snowfall:	O in.	O in.	Up to 2 in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Sunny skies.	Partly cloudy skies.	Cloudy skies with a chance of snow showers in the afternoon.
Temperatures:	31 to 37 deg. F.	11 to 18 deg. F.	25 to 31 deg. F.
Wind direction:	W shifting to S in the afternoon.	SW	SW
Wind speed:	15 to 20 mph with gusts to 35 mph.	30 to 35 mph with gusts to 50 mph, increasing to 40 to 45 mph with gusts to 65 mph after midnight.	45 to 50 mph with gusts to 75 mph, decreasing to 35 to 40 mph with gusts to 60 mph in the afternoon.
Expected snowfall:	O in.	O in.	Up to 2 in.