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 cold low pressure system moving through the area should keep temperatures well below normal today with daytime highs only reaching into the mid to upper 20's in the mountains. Even though this system does not have very much moisture associated with it some scattered snow showers that produce little measurable accumulation could develop across the region by this afternoon. These convective snow showers could also produce some thunderstorms due to the instability in the atmosphere. By tonight the chance of showers should decrease and cloud cover that developed this afternoon should start to dissipate. A high pressure ridge should begin to approach the region tomorrow allowing temperatures to climb into the 30's and skies to continue clearing. After decreasing last night, the winds should remain light to moderate through tomorrow. 

Recent Observations:

Strong winds along the ridgelines continued to transport snow on Elephant's Back, Castle Peak, and on Incline Lake Peak yesterday. Due to the limited amount of snow available for transport, the winds slabs that did form in these areas only reached 6-10 inches in depth and did not extend very far down slope. In all three of these areas snowpit data showed that the recent snow continues to gain strength. Ski cuts on wind loaded test slopes on Incline Lake Peak and on Elephant's Back did not produce any cracking or other signs of instability. On Castle Peak some minor cracking did occur on the most heavily wind loaded slopes in response to the weight of a skier. In all three areas a frozen melt freeze crust existed on the the windward W-SW-S aspects  and 2-10 inches of new snow on top of a crust existed on the wind loaded N-NE-E aspects. Some small patches of terrain existed without a crust under the new snow on the most shaded and sheltered N aspects above 8000 ft.

Today's Avalanche Concern: Wind Slabs

Settlement and consolidation in the snowpack has caused the shallow wind slabs that formed over the last two days to become more difficult to trigger. Isolated pockets of terrain where human triggering of these slabs remains possible may still exist on the most  heavily wind loaded N-NE-E aspects in near and above treeline terrain especially in the northern half of the forecast area where more snow fell. Unsupported slopes and complex or extreme terrain where wind loading has occurred will remain suspect today.  

Deep slab avalanche and persistent weak layer concerns:

Due to the depth (5 to 8 ft down) of the persistent weak layer on the NW-N-NE aspects and the strength of the snow above it, triggering a deep slab avalanche has become unlikely. Even the avalanche cycle that occurred on April 1^st did not add enough force to the snowpack to break through the strong snow on top of the persistent weak layer. At this time data indicates breaking this layer would require an extremely large trigger or significant weakening of the snowpack for these avalanches to begin occurring again in almost all of the areas where this layer exists.

The bottom line:

Isolated pockets of MODERATE avalanche danger may still remain in the most heavily wind loaded areas on N-NE-E aspects on slopes 35 degrees and steeper in near and above treeline terrain. For all other areas, avalanche danger is LOW.

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	9-17 deg. F.
Max. temperature in the last 24 hours:	23-33 deg. F.
Average wind direction during the last 24 hours:	Southwest
Average wind speed during the last 24 hours:	25-40 mph
Maximum wind gust in the last 24 hours:	80 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	44-90 inches

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

For 7000-8000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Partly cloudy this morning with some scattered snow showers developing after 10 am. There is a slight chance of thunderstorms in the afternoon.	Mostly cloudy becoming partly cloudy with isolated thunderstorms in the evening	Partly cloudy
Temperatures:	23-31 deg. F.	8-15 deg. F.	33-39 deg. F.
Wind direction:	West	West	West
Wind speed:	15-20 mph	10-15 mph with gusts to 25 mph	10-15 mph with gusts to 25 mph
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:	Partly cloudy this morning with some scattered snow showers developing after 10 am. There is a slight chance of thunderstorms in the afternoon.	Mostly cloudy becoming partly cloudy with isolated thunderstorms in the evening	Partly cloudy
Temperatures:	17-25 deg. F.	8-14 deg. F.	24-32 deg. F.
Wind direction:	West	Northwest	West
Wind speed:	20-30 mph with gusts to 45 mph	15-25 mph with gusts to 35 mph	20-30 mph with gusts to 35 mph increasing to 45 mph in the afternoon
Expected snowfall:	O in.	O in.	O in.