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 April 11, 2008:


April 11, 2008 at 0:00 am

Forecast Discussion:


This advisory was posted on April 11, 2008 7:00 AM

A map of the SAC forecast area is available on our home page.

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Today's Advisory:
This morning the avalanche danger is LOW for all elevations and aspects. Some small, isolated pockets of MODERATE danger could develop on SE-S-SW aspects or on other aspects where pockets of unconsolidated snow linger on slopes steeper than 38 degrees due to daytime warming.

Winds should decrease today as the strong high pressure ridge impacts the forecast area. Sunny, warm weather will accompany this ridge through the weekend. As the winds diminish the temperatures should climb to almost 60 deg. F below 8000 ft today and could reach the mid 50's above 8000 ft.

Warmer air temperatures and intense solar radiation will cause more extensive melting and allow free water to form deeper in the snowpack today. On southerly aspects, the snowpack is well adjusted to the daily melt-freeze conditions that have occurred over the past 6 weeks. Well established melt water channels in the snowpack will help drain the free water from the snowpack. This drainage should help limit the weakening of the snowpack due to free water forming wet, saturated, weak layers below the snow surface. The northerly aspects should also see some melting today; however, it should not be significant enough to form large wet snow instabilities due to the limited amount of direct sunlight that these aspects receive. Some small and isolated pockets of shallow unconsolidated snow linger on north aspects at the upper elevations. Observations from across the forecast area continue to show a strong, well bonded snowpack below the surface layers at all elevations and on all aspects.

Enough melting could occur by late afternoon today for some human triggerable wet snow sluffs to occur on steep SE-S-SW aspects. Some other small wet surface instabilities like pinwheels and point release slides could also occur on steep, sun exposed northerly aspects where pockets of unconsolidated snow still exist. The strong overnight refreeze, cool east winds, and well established drainage channels in the snowpack should keep these instabilities isolated and small. Large widespread wet snow avalanche activity including wet slab activity should be unlikely today. Expect slopes to soften quickly today and plan to be off of any sun exposed slopes before they get too soft and wet. Use observations and simple tests like stepping into the snow (if you sink into wet snow above your ankles it is a good time to move to a different slope) to help make that decision.

The bottom line: This morning the avalanche danger is LOW for all elevations and aspects. Some small, isolated pockets of MODERATE danger could develop on SE-S-SW aspects or on other aspects where pockets of unconsolidated snow linger on slopes steeper than 38 degrees due to daytime warming.

Andy Anderson, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 27 deg. F
Max. temperature at Sierra Crest past 24 hours: 46 deg. F.
Average wind direction at Sierra Crest past 24 hours: East northeast
Average wind speed at Sierra Crest past 24 hours: 26 mph
Maximum wind gust at Sierra Crest past 24 hours: 49 mph
New snowfall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 75 inches
Mountain Weather Forecast For Today:
Sunny and warmer.
Temperature forecast for 8,000 to 9,000 feet: 49 to 55 deg. F
Ridgetop winds forecast for the Sierra Crest: East at 15 to 25 mph with gusts to 45 mph decreasing 10 to 20 mph in the afternoon.
Snowfall expected in the next 24 hours: 0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:

Today, sunny skies with daytime highs around 58 deg. F. East winds at 10 mph.

Tonight, clear skies with overnight lows around 32 deg. F. East winds at 10 mph.

For Saturday, sunny skies with daytime highs 60 to 66 deg. F. and light winds.

Above 8000 Feet:

Today, sunny skies with daytime highs 49 to 55 deg. F. East winds at 15 to 25 mph with gusts to 45 mph decreasing 10 to 20 mph in the afternoon.

Tonight, clear skies with overnight lows 30 to 36 deg. F. East winds at 10 to 20 mph.

For Saturday, sunny skies with daytime highs 53 to 59 deg. F. East winds at 10 to 20 mph becoming light and variable 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:

  Friday: Friday Night: Saturday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Friday: Friday Night: Saturday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.