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 March 10, 2007:


March 10, 2007 at 1:00 am

Forecast Discussion:


This advisory was posted on Saturday, March 10th, 2007 at 6:59 am

The bottom line: Avalanche danger is LOW for most areas. Isolated pockets of MODERATE danger will develop today below 8,500' on E-SE-S-SW aspects, 35 degrees and steeper in response to daytime warming. Isolated human triggered wet snow avalanches are possible. Normal caution is advised while traveling in the backcountry.

The cloud cover that dominated the northern half of the forecast area yesterday is moving off to the east this morning as high pressure is building into the area. A few high clouds are expected to linger over the mountains today. Daytime high temperatures will only warm a few degrees over yesterday, but significantly greater amounts of solar radiation will be observed today. Ridgetop wind speeds decreased overnight and are expected to remain light through Sunday. Daytime air temperatures are expected to continue to warm through Monday.

Widespread melt-freeze snow surface conditions exist throughout the forecast area. On southerly aspects, these conditions extend above 9000'. On northerly aspects above 8,500', some pockets of well settled, unconsolidated snow linger in areas protected from wind and sun. The snow surface in sun exposed areas on E-SE-S-SW aspects will soften rapidly today.

The snowpack is in a transition state from winter to spring. Even on south aspects, the snowpack has not become isothermal. Cold winter snow exists below the top melt-freeze layer. Warm air temperatures and spring solar radiation are causing the surface snow to melt quickly each morning, rapidly allowing deep ski and boot penetration, as well as significant human triggered roller ball and pinwheel activity. Most E-SE aspects in the 7,000-8,500' range are at their prime condition for riding around 9am.

Warm daytime air temperatures over the past several days have produced roller balls and large human triggered pinwheels on the majority of aspects, especially below 8,500'. No human triggered or natural wet snow avalanches have been reported, despite these signs of surface instability. As air temperatures continue to warm over the next few days, the possibility of human triggered avalanche activity will increase. Keep in mind that if boot penetration exceeds boot top height in wet snow, it is time to move to a less sun exposed aspect or call it a day, as human triggered wet snow avalanches are becoming possible at that time on steep terrain.

The bottom line: Avalanche danger is LOW for most areas. Isolated pockets of MODERATE danger will develop today below 8,500' on E-SE-S-SW aspects, 35 degrees and steeper in response to daytime warming. Isolated human triggered wet snow avalanches are possible. Normal caution is advised while traveling in the backcountry.

At this time, we are still short $3,000 in funding for our operating budget this winter. If you use this service with any regularity and would like to continue to do so, please show your financial support for the Sierra Avalanche Center. You may 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. A graph showing the amount of fundraising completed this season and our overall budget is available by clicking here. The financial support already received this winter from a variety of users is greatly appreciated.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 28 deg. F
Max. temperature at Sierra Crest past 24 hours: 39 deg. F
Average wind direction at Sierra Crest past 24 hours: Westerly
Average wind speed at Sierra Crest past 24 hours: 30 mph
Maximum wind gust at Sierra Crest past 24 hours: 50 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 88 inches

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Mountain Weather Forecast For Today:
Sunny to partly cloudy skies
Temperature forecast for 8,000 to 9,000 feet: 43 to 49 degrees F.
Ridgetop winds forecast for the Sierra Crest: Northwesterly 15-25 mph.
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:

7000 to 8000 Feet

Today, sunny to partly cloudy with daytime highs 48 to 54 degrees F. North winds at 10 to 15 mph. Tonight, clear skies with overnight lows 31 to 37 degrees F. East winds at 10 to 15 mph. Sunday, sunny skies with daytime highs around 59 degrees F. Northeast winds at 10 to 15 mph are expected.

Above 8000 Feet

Today, sunny to partly cloudy with daytime highs 43 to 49 degrees F. Northwest winds at 15 to 25 mph. Tonight, clear skies with overnight lows around 36 degrees F. North winds at 10 to 15 mph. Sunday, sunny skies with daytime highs 51 to 57 degrees F. Northeast winds at 15 to 20 mph are expected.


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:

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

For 8000-9000 ft:

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