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 December 4, 2006:

December 4, 2006 at 1:00 am

Forecast Discussion:

This advisory was posted on Monday, December 4, 2006 at 3:49 pm

Our SAC Ski Day tickets are now available. This is an excellent opportunity for you to make a donation to SAC by purchasing a 1/2 price lift ticket that was donated to us by the ski area. All of the proceeds from your ticket purchase go to SAC and you get to go skiing. This year the tickets can be bought online thanks to (just click on the link above). Our first ski day is at Mt. Rose on December 17th. We hope to see you there.

Ridge top winds have settled down across the forecast area. Air temperatures are warming and an air temperature inversion remains, keeping the mountain tops quite warm. High pressure will remain through the next several days with the next chance of snow arriving at the end of this week.

The current snowpack remains highly variable with snow depths above 7,500' ranging from bare ground to nearly 3 feet deep. Snow surface conditions are highly variable as well with a mix of melt-freeze crust, shallow wind slab, and some lingering powder. Melt-freeze crust exists in the sun exposed areas on S-SW-W aspects below 8,000'. All areas above treeline have been scoured by wind, but a few pockets of nice recrystalized powder can be found above 8,500' on the more wind protected NW-N aspects. Deeper in the snowpack, faceted snow crystals have formed near crust layers on E-N-W aspects above 7,500' and have been observed both along the Sierra Crest and in the Mount Rose area. These faceted crystals are showing different behavior based on their depth in the snowpack and amount of sun exposure received. In the heavily wind scoured and sun exposed areas, the snow pack is shallow enough that warmth from the sun is penetrating into the snowpack and allowing the faceted crystals to bond to one another despite continued below freezing snow surface temperatures. On the very shaded N aspects, we observed our first true cupped depth hoar crystals today in the Mount Rose area on steeper N aspects above 9,500'. These crystals are very poorly bonded and continue to grow in size, now up to 4mm. Warmer air temperatures this week will slow and possibly reverse much of the faceting process in sun exposed areas. We will continue to keep an eye on the snowpack as it is not in good shape to receive significant new snow loading at this time.

Currently, natural or human triggered avalanches are unlikely. The greatest hazards to backcountry travelers remains the lurking presence of shallow buried rocks, down trees, and stumps. Hitting these objects could cause you to fall onto similar hard objects and cause significant injury. If you want to get out and about, your best options remain xc-skiing, xc oriented ski tours, snowmobiling on snow covered roads, or snowshoeing.

Brandon Schwartz , Avalanche Forecaster


Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 34 deg. F
Max. temperature at Sierra Crest past 24 hours: 41 deg. F
Average wind direction at Sierra Crest past 24 hours: eastnortheasterly
Average wind speed at Sierra Crest past 24 hours: 5 mph
Maximum wind gust at Sierra Crest past 24 hours: 9 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 11 inches

Mountain Weather Forecast For Tuesday:
Mostly sunny skies.
Temperature forecast for 8,000 to 9,000 feet: 39 - 49 deg. F
Ridgetop winds forecast for the Sierra Crest: northwesterly 5 - 15 mph G 20 mph
Snowfall expected in the next 24 hours: 0 inches

2 Day Mountain Weather Forecast:
7000 to 8000 Feet
For Tuesday, sunny skies with daytime highs 46 to 52 degrees F. Overnight lows 22 to 32 degrees F. under clear skies. Wednesday will be sunny with daytime highs 47 to 53 degrees.
Above 8000 Feet
For Tuesday, sunny skies with daytime highs 39 to 49 degrees F. Overnight lows 25 to 35 degrees F. under clear skies. Monday will be sunny with daytime highs 40 to 50 degrees F. Light northwesterly ridgetop winds for Tuesday are expected on shift to light to moderate southwesterly on Wednesday.

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:

  Monday: Monday Night: Tuesday:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Monday: Monday Night: Tuesday:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.