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 February 13, 2008:


February 13, 2008 at 1:00 am

Forecast Discussion:


This advisory was posted on February 13, 2008 6:56 AM
Click here for a detailed map of the SAC forecast area

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Today's Advisory:

Avalanche danger is LOW for all elevations and aspects. Normal caution is advised.

A cold front associated with a weak weather system is moving into the forecast area this morning. Cooling daytime air temperatures and the possibility of snow showers will spread from north to south by early afternoon. Ridgetop winds are moderate from the southwest this morning. Winds are expected to increase in speed and rotate clockwise around to the east overnight.

Remote sensors are indicating air temperatures above 8,000' have dropped below freezing overnight. Temperatures below 8,000' never dropped below freezing last night. Increasing cloud cover is expected to have reduced the amount of snow surface refreeze due to radiational cooling below 8,000'. A brief window of wet snow instability involving the top 4 to 6 inches of the snowpack may exist below 7,500' this morning. Any avalanche activity that occurs is expected to be very isolated and created by human triggering. As air temperatures cool today, this window of instability is expected to close.

Snowpack observations from all over the forecast area indicate an overall well bonded snowpack on northerly aspects. A well bonded snowpack exists below the top 4 to 6 inches of recent melt-freeze snow on southerly aspects. At higher elevations on southerly aspects where the snowpack received a solid refreeze overnight, the entire height of the snowpack is well bonded. Very isolated human triggered avalanche activity is unlikely but not impossible this morning on southerly aspects below 7,500'. In all other areas, natural and human triggered avalanches are unlikely today.

The bottom line: Avalanche danger is LOW for all elevations and aspects. Normal caution is advised.

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

Brandon Schwartz, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 29 deg. F
Max. temperature at Sierra Crest past 24 hours: 48 deg. F.
Average wind direction at Sierra Crest past 24 hours: Southwest
Average wind speed at Sierra Crest past 24 hours: 22 mph
Maximum wind gust at Sierra Crest past 24 hours: 53 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 83 inches

Mountain Weather Forecast For Today:
Mostly cloudy skies with snow showers.
Temperature forecast for 8,000 to 9,000 feet: around 32 deg. F
Ridgetop winds forecast for the Sierra Crest: West at 35 to 45 mph with gusts to 75 mph, shifting to northwest at 20 to 30 with gusts to 55 mph in the afternoon.
Snowfall expected in the next 24 hours: 0 to 1 inch

2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, mostly cloudy skies with scattered snow showers. Isolated snow showers in the afternoon. Daytime highs around 32 deg. F. West winds at 10 to 15 mph with gusts to 25 mph. Winds shifting to the north this afternoon.

Tonight, partly cloudy skies with isolated snow showers in the evening. Overnight lows around 16 deg. F. Northeast winds at 15 to 25 mph with gusts to 50 mph.

For Thursday, sunny skies with daytime highs around 35 to 41 deg. F. East winds at 15 to 25 mph with gusts to 45 mph. Gusts decreasing to 35 mph in the afternoon.

Above 8000 Feet:
Today, mostly cloudy skies with scattered snow showers. Isolated snow showers in the afternoon. Daytime highs around 32 deg. F. West winds at 30 to 45 mph with gusts to 75 mph, shifting to northwest at 20 to 30 with gusts to 55 mph in the afternoon.

Tonight, partly cloudy skies with isolated snow showers in the evening. Overnight lows around 14 deg. F. Northeast winds at 35 to 50 mph with gusts to 90 mph. Winds increasing to 45 to 60 mph with gusts to 105 mph after midnight.

For Thursday, partly cloudy skies with daytime highs around 30 deg. F. Northeast winds at 35 to 50 mph with gusts to 90 mph. Winds decreasing to 25 to 35 mph with gusts to 65 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:

  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.