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.

One more day of sunny skies and warm air temperatures will occur today before a change to a colder and unsettled weather pattern begins on Thursday. A slight chance of thunderstorms exists again this afternoon for areas south of Lake Tahoe. Maximum daytime air temperatures are expected to reach the mid 50s to low 60s at all elevations today. This will be 5 to 10 degrees cooler than yesterday. An air temperature inversion is once again in place this morning with air temperatures below 7,000' in the 30s. Air temperatures above 7,000' are in the mid to upper 40s in nearly all locations. Ridgetop winds shifted from northeast to southwest yesterday and remain light to moderate in speed this morning. Wind speeds are expected to increase this afternoon, overnight, and tomorrow.

Yesterday, observations made on Mt. Judah (Donner Summit area) indicated that a fair surface refreeze had occurred overnight. Snow surface melting on E and S aspects occurred quickly, with all evidence of the previous night's refreeze melted by 10:30 am at the 8,400' level. Wet snow sluffs and large roller balls were easy to trigger on E aspects steeper than 40 degrees between 7,800' and 8,400' at 10 am. The snow surface on W and N aspects remained more frozen and supportable with signs of instability holding off until afternoon.

Last night, a fair snow surface refreeze is expected to have occurred above 7,000' and a stronger refreeze is expected to have occurred below 7,000' due to the air temperature inversion and radiational cooling of the snowpack. Today, the combination of well above freezing air temperatures at the upper elevations and rapid daytime warming will cause areas of instability to form by mid morning. Most avalanche activity is expected to occur as human triggered wet loose snow avalanches on steep E-SE-S-SW-W aspects. Some smaller areas of wet surface snow instability are expected to form on steep NW-N-NE aspects, mainly below 9,500' in sun exposed areas. Natural avalanche activity is unlikely but not impossible today. Any natural avalanche activity should be limited to areas of cornice collapse that could create larger wet loose snow avalanches. In areas where the snowpack sits on top of steep granite slabs, isolated wet slab avalanches are not impossible. At this time, wet slab avalanches remain unlikely on E-SE-S-SW-W aspects due to the already well established drainage of free water from the snowpack. With free water limited to the top 6 inches of the snowpack in most NW-N-NE aspect avalanche start zones, wet loose surface snow instability remains more likely than deeper wet slab instability at this time.

The bottom line:

Early this morning, avalanche danger is LOW for all elevations and aspects. Avalanche danger will rise to MODERATE on E-SE-S-SW-W aspects 37 degrees and steeper in response to daytime warming. Pockets of MODERATE danger will also form on NW-N-NE aspects, 37 degrees and steeper as warming occurs.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	46 deg. F.
Max. temperature in the last 24 hours:	60 deg. F.
Average wind direction during the last 24 hours:	Northeast shifting to southwest.
Average wind speed during the last 24 hours:	16 mph
Maximum wind gust in the last 24 hours:	30 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	125 inches

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

For 7000-8000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Sunny skies in the morning, becoming partly cloudy in the afternoon with isolated thunderstorms mainly south of Lake Tahoe.	Partly cloudy skies with isolated thunderstorms in the evening south of Lake Tahoe.	Partly cloudy skies in the morning, becoming mostly cloudy.
Temperatures:	57 to 65 deg. F.	35 to 42 deg. F.	47 to 54 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	10 to 15 mph with gusts to 25 mph in the afternoon.	10 to 20 mph with gusts to 30 mph.	10 to 20 mph with gusts to 35 mph, increasing to 20 to 30 mph with gusts to 45 mph in the afternoon.
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:	Sunny skies in the morning, becoming partly cloudy in the afternoon with isolated thunderstorms mainly south of Lake Tahoe.	Partly cloudy skies with isolated thunderstorms in the evening south of Lake Tahoe.	Partly cloudy skies in the morning, becoming mostly cloudy.
Temperatures:	51 to 57 deg. F.	35 to 42 deg. F.	37 to 47 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	Around 10 mph in the morning, increasing to 15 to 25 mph with gusts to 45 mph in the afternoon.	15 to 25 mph with gusts to 45 mph, increasing to 20 to 35 mph with gusts to 65 mph after midnight.	25 to 40 mph with gust up to 85 mph.
Expected snowfall:	O in.	O in.	O in.