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 Avalanche Advisory was published on January 31, 2007:

January 31, 2007 at 1:00 am

Forecast Discussion:

This advisory was posted on Wednesday, January 31, 2007 at 5:55 pm

The bottom line: Avalanche danger is LOW for all elevations and aspects. Human triggered avalanches are unlikely, but not impossible near treeline on NW-N-NE aspects, 35 degrees and steeper.

Our next fund raiser is another ski day this Sunday, February 4th at Homewood. Tickets are on sale now at Snowbomb.com. If you can't make it but would still like to help out, please make a tax deductible donation directly to us via Paypal or by sending a check to our address listed above, c/o the Truckee Ranger Station. Your support is what makes the Sierra Avalanche Center possible. For more details on the current financial situation please click here.

High pressure continues to dominate the forecast area. Northerly ridgetop winds are expected to increase tonight and Thursday as a dry weather disturbance pass by the forecast area. Air temperatures are on a slight cooling trend that is expected to last into Friday. Air temperatures are then expected to warm through the weekend.

Snowpack temperatures on northerly aspects have remained cold, despite above average January air temperatures over the past week. The faceting process continues to work on the snowpack, especially on northerly aspects throughout the forecast area. Significant faceting has been observed at all elevations in the Mount Rose area. Along the Sierra Crest, significant faceting exists in the shallow snowpack below 8,000'. Above 8,000', a deeper snowpack ranging from 4-5 feet deep, is showing less faceting and overall better stability. For all areas, relative weak layers exist within the snowpack. Layers of faceted snow and layer interfaces with crusts continue to yield moderate shear failure in response to layer bonding tests. Very isolated areas exist on northerly aspects where human triggered avalanches are unlikely but not impossible on these weak layers.

Faceting of surface snow below treeline on northerly aspects has created enjoyable, unconsolidated snow surface conditions in areas that have not been tracked by others. A daily melt-freeze cycle continues on southerly aspects. Wide spread surface hoar has been observed throughout the forecast area above 8,000' on northerly aspects and is surviving daytime warming in shaded areas on other aspects.

No avalanche activity was reported yesterday.

The bottom line: Avalanche danger is LOW for all elevations and aspects. Human triggered avalanches are unlikely, but not impossible near treeline on NW-N-NE aspects, 35 degrees and steeper.

The next scheduled update to this advisory will occur tomorrow afternoon.

Brandon Schwartz , Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 18 deg. F
Max. temperature at Sierra Crest past 24 hours: 36 deg. F
Average wind direction at Sierra Crest past 24 hours: easterly
Average wind speed at Sierra Crest past 24 hours: 15 mph
Maximum wind gust at Sierra Crest past 24 hours: 28 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 34 inches

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Mountain Weather Forecast For Thursday:
Clear skies.
Temperature forecast for 8,000 to 9,000 feet: 31 - 37 deg. F
Ridgetop winds forecast for the Sierra Crest: north to northwest 25 - 35 mph, G 50 mph
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
Tonight, clear with lows 20 to 25 degrees F. North winds 10 to 20 mph. Thursday, sunny skies with daytime highs 37 to 42 degrees F. Winds are forecasted to be out of the north at 15 to 25 mph.

Above 8000 Feet
Tonight, clear with lows 24 to 29 degrees F. Northwest winds 20 to 30 mph, gusting to 50 mph after midnight. Thursday, sunny skies with daytime highs 31 to 37 degrees F. Winds are forecasted to be north to northwest at 25 to 35 mph, gusting to 50 mph.


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:
  Wednesday: Wednesday Night: Thursday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:
  Wednesday: Wednesday Night: Thursday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.