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.

This advisory was posted on February 16, 2008 7:00 AM
Click here for a detailed map of the SAC forecast area

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Today's Advisory:

This morning, avalanche danger is LOW for all elevations and aspects. Areas of MODERATE avalanche danger will develop on SE-S-SW-W aspects, 37 degrees and steeper in response to daytime warming.

Yesterday most of the forecast area did not climb above freezing until late afternoon or evening. The temperatures continued to climb overnight in many areas with overnight lows along the ridges ranging from just below freezing to the mid to upper 30's. The temperatures above 8000' are already a few degrees above freezing this morning. Below 8000' temperatures are much colder due to an inversion of cold air trapped in the valleys. Continued high pressure should cause air temperatures to warm well above freezing at all elevations today. The winds should also continue to calm.

Only the most sun exposed snow surfaces softened yesterday because the temperatures only climbed above freezing after the sun's radiation had peaked. These snow surfaces that softened yesterday quickly refroze overnight due to radiational cooling. Clear skies, warmer air temperatures,and light winds should cause faster, more widespread melting on sun exposed slopes today creating free water in the upper part of the snowpack. As this melt water dissolves the bonds within and between layers in the snowpack areas of wet snow instability should form on steep SE-S-SW-W aspects. Observations from northerly aspects continue to show a well bonded and strengthening snowpack structure throughout the forecast area. Today snow surface conditions will continue to be a mix of wind scoured and wind affected surfaces on northerly aspects above treeline; pockets of soft snow on shaded, wind sheltered northerly aspects below treeline; and melt/freeze (corn/crusts) snow conditions on the southerly aspects.

Wet snow avalanche activity that fails in response to human triggering will become possible today on steep SE-S-SW-W aspects as daytime warming occurs. Most of this activity should be in the form of wet surface instabilities like pinwheels and point release avalanches. Wet slab avalanche activity is unlikely but it is not impossible today. Simple clues and tests like pinwheels, roller balls, and how deep boots penetrate into wet snow (ankle deep or deeper is a bad sign) are good indicators of when it is time to find more frozen slopes. Natural avalanche activity is unlikely today.

The bottom line: This morning, avalanche danger is LOW for all elevations and aspects. Areas of MODERATE avalanche danger will develop on SE-S-SW-W aspects, 37 degrees and steeper in response to daytime warming.

Please send us your snow, weather, and avalanche observations by clicking the submit observations link on our contact page.

Andy Anderson, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 32 to 36 deg. F
Max. temperature at Sierra Crest past 24 hours: 42 deg. F.
Average wind direction at Sierra Crest past 24 hours: Northeast
Average wind speed at Sierra Crest past 24 hours: 20 mph
Maximum wind gust at Sierra Crest past 24 hours: 69 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 81 inches
Mountain Weather Forecast For Today:
Sunny and warm.
Temperature forecast for 8,000 to 9,000 feet: 42 to 48 deg. F
Ridgetop winds forecast for the Sierra Crest: Northeast at 10 mph
Snowfall expected in the next 24 hours: 0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, sunny skies with daytime highs 48 to 54 deg. F. and light winds.

Tonight, clear skies with overnight lows 21 to 31 deg. F. and light winds.

For Sunday, sunny skies with daytime highs around 51 deg. F. Light winds in the morning shifting to the northeast and increasing to 10 mph in the afternoon.

Above 8000 Feet:
Today, sunny skies with daytime highs 42 to 48 deg. F. Northeast winds at 10 mph.

Tonight, clear skies with overnight lows 25 to 33 deg. F. and light winds.

For Sunday, sunny skies with daytime highs around 45 deg. F. Light winds shifting to the north and increasing to 10 mph in the afternoon.

The bottom line:

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	deg. F.
Max. temperature in the last 24 hours:	deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours:	mph
Maximum wind gust in the last 24 hours:	mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	inches

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

For 7000-8000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.