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 November 19, 2010:


November 19, 2010 at 7:44 am

For most of today, avalanche danger is LOW for all elevations and aspects. Isolated areas of instability may form this evening after the onset of snowfall sometime this afternoon. A significant increase in avalanche danger is expected overnight into Saturday.


Forecast Discussion:


A significant winter storm is starting to impact the forecast area. Gale force ridgetop winds out of the southwest began yesterday and will continue through this weekend. Snowfall is expected to begin sometime this afternoon or evening with the potential for 4 to 6 feet of new snow accumulating above 7,000' by Monday morning. Air temperatures at most elevations will be in the mid to upper 30s today, falling into the teens overnight. Maximum daytime air temperatures above 8,000' are expected to remain in the teens and single digits for the weekend and possibly beyond.

Observations:

Observations made over the past two days in the Tamarack Peak (Mount Rose area) and Elephant's Back (Carson Pass) areas reveal a mix of bare ground, crusts, and lightly faceted snow (click here for pit profiles and photos). This limited number of observations has revealed no evidence of snowpack instability despite the crusts and lightly faceted snow crystals in the existing snowpack. Old snow on the ground is most abundant on N-NE-E aspects, with snow depths generally ranging from 4 to 16 inches. A strong east wind event that occurred during the past week scoured many N-NE-E aspects and avalanche start zones in near and above treeline areas.

Avalanche Concerns:

Based on a limited number of observations, the shallow existing snowpack appears to be in good condition to handle new snow loading. Avalanche concerns focus on storm snow from the approaching storm. After the onset of snowfall later today, isolated areas of instability may form as early as this evening. These pockets of unstable snow will form first in the most heavily wind loaded areas on N-NE-E aspects and become more widespread overnight. Snowpack instability is expected to become increasingly widespread this weekend.


The bottom line:

For most of today, avalanche danger is LOW for all elevations and aspects. Isolated areas of instability may form this evening after the onset of snowfall sometime this afternoon. A significant increase in avalanche danger is expected overnight into Saturday.


Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest


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

0600 temperature: 27 to 34 deg. F.
Max. temperature in the last 24 hours: 42 to 44 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 45 mph
Maximum wind gust in the last 24 hours: 110 mph
New snowfall in the last 24 hours: O inches
Total snow depth: 0 to 16 inches

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

For 7000-8000 ft:

  Friday: Friday Night: Saturday:
Weather: Increasing clouds with snow developing in the afternoon. Cloudy skies with snow. Cloudy skies with snow.
Temperatures: 35 to 41 deg. F. 14 to 21 deg. F. 15 to 22 deg. F.
Wind direction: SW SW SW
Wind speed: 20 to 30 mph with gusts to 60 mph. 20 to 30 mph with gusts to 55 mph. 20 to 30 mph with gusts to 55 mph.
Expected snowfall: 1 to 3 in. 10 to 16 in. 6 to 12 in.

For 8000-9000 ft:

  Friday: Friday Night: Saturday:
Weather: Increasing clouds with snow developing in the afternoon. Cloudy skies with snow. Cloudy skies with snow.
Temperatures: 30 to 36 deg. F. 10 to 17 deg. F. 12 to 19 deg. F.
Wind direction: SW SW SW
Wind speed: 40 to 55 mph with gusts to 95 mph. 40 to 60 mph with gusts to 85 mph. 45 to 60 mph with gusts to 90 mph.
Expected snowfall: 1 to 3 in. 10 to 18 in. 6 to 12 in.

December Donor Drive

Winter is back and so is SAC! Everything we do hinges on the generous support of users like you.

Please help support SAC with a tax-deductible donation today!

DONATE

No Thanks