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.

Snowfall tapered off by midday yesterday, and the clouds started to clear. During the morning most areas received another 2-3 inches of snow with some sensors reporting up to 5 inches. The forecast calls for a break in the weather today with some sunshine and calmer winds this morning. By this afternoon another low pressure should begin to push more clouds into the region and cause the southwest winds to start increasing again. A slight chance of some light snow showers exists over the region tonight. More widespread snow should hold off until this system arrives tomorrow afternoon. Snowfall rates could reach 2 inches per hour tomorrow afternoon and evening. By the end of the day tomorrow, the forecast calls for up to another 6 inches of snow above 7000 ft. This storm should persist through Friday night with more snow and wind during the night.

Observations:

Observations on Jake's Peak yesterday showed some instabilities due to wind slabs not bonding completely to the snow below them and due to weaknesses within the storm snow. Near and above treeline, dense wind slabs existed on top of lighter storm snow which then rested on a thin crust. Ski cuts did not produce cracking or fractures on test slopes where these wind slabs existed unless those slopes had been undercut. However, stability tests showed that human triggered fractures remained possible (more info, pit profile). Below treeline the new snow rested on top of several inches of wet snow. The bonds between the new snow and the wet snow had not fully formed. Ski cuts on steep N-NE facing test slopes below 8000 ft produced sluffs that slid on this interface and entrained all of the new snow. 

Avalanche Concern #1: Lingering Wind Slabs

Even though the bonds between the dense wind slabs and the lighter snow below them should have gained some strength, human-triggered avalanche activity involving these wind slabs will remain possible today. The wind-loaded N-NE-E aspects and cross-loaded NW and SE aspects near and above treeline will hold the largest and most fragile wind slabs. Below treeline in open, wind-loaded areas smaller wind slabs still exist. As the snowpack continues to settle and strengthen today these slabs will become more difficult to trigger; however, this consolidation will not happen in a uniform manner. Areas of instability will linger on within larger areas of mostly stable snow.

Avalanche Concern #2: Rapid Warming of the New Snow

As the intense March sun hits the new snow this morning, it will quickly warm the snow. This rapid warming will weaken the snowpack and allow avalanche activity to become possible on open sun-exposed slopes. Most of this activity should remain limited to roller balls and loose snow sluffs; however, slab avalanches will also be possible on the most sun-exposed slopes. Open, below treeline slopes that face the southern half of the compass will be the most susceptible to these kinds of instabilities. Some of the most sun-exposed higher elevations could also be affected. The extent of these kind of instabilities will depend on the timing and extent of the cloud cover that is supposed to move into the area. When the clouds move into the area this afternoon, instabilities due to rapid warming should decrease.

The bottom line:

Near and above treeline on slopes steeper than 35 degrees, MODERATE avalanche danger exists on N-NE-E aspects with pockets of MODERATE danger on all other aspects. Below treeline on open slopes steeper than 35 degrees, MODERATE danger exists on sun-exposed SE-S-SW aspects with pockets of MODERATE danger on other aspects. 

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	9-15 deg. F.
Max. temperature in the last 24 hours:	Occurred yesterday at 6am: 23-30 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	25-35 mph
Maximum wind gust in the last 24 hours:	97 mph
New snowfall in the last 24 hours:	2-6 inches
Total snow depth:	113-158 inches

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

For 7000-8000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Partly cloudy becoming mostly cloudy in the afternoon.	Mostly cloudy with isolated snow showers after midnight	Slight chance of snow in the morning becoming widespread snow in the afternoon.
Temperatures:	31-37 deg. F.	13-20 deg. F.	30-36 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	10-15 mph with gusts to 30 mph	10-15 mph with gusts to 30 mph	15-25 mph with gusts to 40 mph increasing to 20-35 mph with gusts to 50 mph in the afternoon
Expected snowfall:	O in.	O in.	up to 6 in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Partly cloudy becoming mostly cloudy in the afternoon.	Mostly cloudy with isolated snow showers after midnight	Slight chance of snow in the morning becoming widespread snow in the afternoon.
Temperatures:	24-30 deg. F.	11-18 deg. F.	24-30 deg. F.
Wind direction:	Southwest	Southwest	Southwest
Wind speed:	20-30 mph with gusts to 35 mph increasing to 45 mph in the afternoon	25-35 mph with gusts to 50 mph increasing to 60 mph after midnight	30-45 mph with gusts to 65 mph increasing to 75 mph in the afternoon
Expected snowfall:	O in.	O in.	up to 6 in.