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 high pressure ridge over the forecast area will begin to shift east today. This will allow for slightly cooler maximum daytime air temperatures and increasing southwest winds. High level cloud cover will begin to build over the forecast area as moisture ahead of an offshore weather system moves towards the region. A slight chance of snow showers is forecast for tomorrow. This morning, remote sensors above 8,000' are reporting air temperatures in the 30s. Maximum daytime air temperatures above 7,000' are forecast to warm into the upper 30s to low 50s today. Ridgetop winds are light to moderate in speed out of the southwest this morning and are forecast to become moderate in speed by this afternoon.

Recent Observations:

Observations made yesterday on Castle Peak (Donner Summit area) revealed that a strong overnight refreeze of wet surface snow from the day before had occurred in nearly all areas. Only below treeline locations with very thick forest canopy cover showed evidence of poor overnight refreeze due to sky obscurement and reduced radiational cooling. Wet surface snow was observed to form during the day. At noon, 1 inch of wet snow existed on top of supportable melt freeze crust on S-SW aspects between 7,200' and 8,500'.

Snowpit tests targeting wind slabs on N-NW aspects between 8,200' and 8,500' revealed stable conditions. However, a thin layer of early stage near crust faceted snow crystals was observed on top of the melt freeze crust, right at the base of the recent storm snow and wind slab. This facet layer was not reactive in propagation tests yesterday, but warrants monitoring. Recent NE winds had scoured the upper portion of avalanche start zones in this area, leaving wind slabs around 1 foot deep in the the middle and lower portions of avalanche paths (pit profile, more info).

Avalanche Problem #1: Loose Wet Avalanches

Mostly clear skies last night are expected to have allowed for good radiational cooling of the snowpack leading to strong overnight snow surface refreeze. Slightly cooler maximum daytime air temperatures today as compared to yesterday and convective cooling from increasing SW winds are expected to slow the rate of snow surface melt today. The amount of wet surface snow that forms today on E-SE-S-SW-W aspects is expected to remain limited to 2 to 3 inches. Only isolated areas where sufficient amounts of wet surface snow form to the point of instability are expected today. Human triggered loose wet snow avalanches are unlikely but not impossible this afternoon on open sun exposed slopes 37 degrees and steeper.

The bottom line:

Avalanche danger is LOW for all elevations and aspects. Isolated areas of loose wet snow instability may form during the afternoon hours on open sun exposed slopes 37 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:	31 to 37 deg. F.
Max. temperature in the last 24 hours:	41 to 50 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:	41 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	49 to 87 inches

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

For 7000-8000 ft:
	Monday:	Monday Night:	Tuesday:
Weather:	Partly cloudy skies.	Partly cloudy skies.	Mostly cloudy skies with a slight chance of snow showers.
Temperatures:	41 to 52 deg. F.	25 to 32 deg. F.	41 to 49 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	Light winds becoming 15 to 20 mph with gusts to 30 mph in the afternoon.	15 to 20 mph with gusts to 35 mph.	15 to 20 mph with gusts to 30 mph.
Expected snowfall:	O in.	O in.	0 to trace in.
For 8000-9000 ft:
	Monday:	Monday Night:	Tuesday:
Weather:	Partly cloudy skies.	Partly cloudy skies.	Mostly cloudy skies with a slight chance of snow showers.
Temperatures:	39 to 45 deg. F.	21 to 28 deg. F.	32 to 42 deg. F.
Wind direction:	SW	SW	SW
Wind speed:	10 to 15 mph with gusts to 25 mph, increasing to 20 to 25 mph with gust to 40 mph in the afternoon.	25 to 35 mph with gusts to 55 mph.	30 to 35 mph with gusts to 50 mph, decreasing to 20 to 25 mph with gusts to 40 mph in the afternoon.
Expected snowfall:	O in.	O in.	0 to trace in.