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.

The well advertised series of storms remains on track to move through the forecast area over the next several days. Snowfall totals thus far are running 3 to 7 inches along the Sierra Crest with the greatest accumulations in the northern areas. Around 2 inches of snow has accumulated in the Carson Range. Light to moderate snowfall is expected this morning. Snowfall is expected to become heavy around mid day and continue into the evening hours with accumulation rates of 2 inches per hour. Additional snow accumulations of 14 to 35 inches above 7,000' are expected over the next 36 hours with the greatest accumulations along the Sierra Crest. Ridgetop winds have shifted between south and southwest over the past 24 hours. Strong south to southwest winds are expected for today with ridgetop gusts up to 100 mph this afternoon. Air temperatures above 7,000' are expected to remain in the 20s today.

Observations:

Observations made yesterday morning in Upper Ophir Creek (Mount Rose area) below treeline at 9,070 on a N aspect 32 degree slope indicated that the existing snowpack is in good condition to handle new snow loading. Neither the October 19 facet layer near the base of the snowpack or the lightly faceted crystals above the January 11 crust displayed characteristics of likely fracture propagation (pit profile and video). This was a significant change in the Oct 19 layer test results performed in this location on Jan 9 (pit profile and video). Observations made after significant snowfall began yesterday afternoon on Donner Pass (Donner Summit area) near treeline at 7,400' on N and NW aspects revealed that 4" to 8" of new snow existed in wind loaded areas by mid afternoon. Ski cuts on small steeper convex slopes and other stability tests revealed no additional signs of instability beyond wind loading (more info).

Avalanche concern #1:

As snowfall continues today, unstable slabs are expected to become increasingly widespread in wind loaded areas. This will occur mainly near and above treeline on NW-N-NE-E aspects. Natural avalanche activity will be possible this afternoon as snowfall intensity increases. Any snowpack failure is expected to occur within the new snow in the vast majority of areas. Slabs 1 to 3+ feet deep can be expected this afternoon and evening in the most heavily wind loaded areas.

Avalanche concern #2:

In very isolated areas, deep slab instability could occur on a layer of lightly faceted snow crystals down at the level of the January 11 crust. This crust exists around 1 foot below the old/new snow interface in most areas. Observations made near Crater Lake (Carson Pass area) on Jan 16 revealed that fracture propagation was possible on this layer (pit profile). Observations made over the past 3 days in the Bear Valley, Mount Rose, and Donner Summit areas found the presence of this crust, but no evidence of instability associated with it (more info).

The bottom line:

This morning, avalanche danger is MODERATE in wind loaded areas near and above treeline. Below treeline, avalanche danger is LOW. This afternoon, avalanche danger is expected to rise to CONSIDERABLE in wind loaded areas near and above treeline on NW-N-NE-E aspects, 35 degrees and steeper. Below treeline, avalanche danger is expected to rise to MODERATE on all aspects, 35 degrees and steeper.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	26 to 28 deg. F.
Max. temperature in the last 24 hours:	30 to 34 deg. F.
Average wind direction during the last 24 hours:	South southwest
Average wind speed during the last 24 hours:	40 mph
Maximum wind gust in the last 24 hours:	83 mph
New snowfall in the last 24 hours:	2 to 7 inches
Total snow depth:	47 to 73 inches

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

For 7000-8000 ft:
	Monday:	Monday Night:	Tuesday:
Weather:	Cloudy skies with snow. High intensity snowfall during the afternoon.	Cloudy skies with snow.	Cloudy skies with snow showers in the morning. Snow in the afternoon.
Temperatures:	26 to 30 deg. F.	13 to 20 deg. F.	23 to 28 deg. F.
Wind direction:	SW	S	S
Wind speed:	20 to 35 mph with gusts to 55 mph.	20 to 35 mph with gusts to 55 mph. Gusts decreasing to 45 mph after midnight.	20 to 30 mph with gusts to 45 mph.
Expected snowfall:	6 to 14 in.	6 to 14 in.	2 to 4 in.
For 8000-9000 ft:
	Monday:	Monday Night:	Tuesday:
Weather:	Cloudy skies with snow. High intensity snowfall during the afternoon.	Cloudy skies with snow.	Cloudy skies with snow showers in the morning. Snow in the afternoon.
Temperatures:	22 to 26 deg. F.	9 to 16 deg. F.	19 to 24 deg. F.
Wind direction:	SW	SW	S
Wind speed:	45 to 65 mph with gusts to 90 mph. Gusts increasing to 100 mph in the afternoon.	45 to 65 mph with gusts to 100 mph. Gusts decreasing to 85 mph after midnight.	40 to 50 with gusts to 90 mph. Winds decreasing to 25 to 35 mph with gusts to 65 mph in the afternoon.
Expected snowfall:	8 to 16 in.	7 to 14 in.	3 to 5 in.