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 25, 2007:

April 25, 2007 at 0:00 am

Forecast Discussion:

This advisory was posted on Wednesday, April 25th, 2007 at 8:15 am

The bottom line: Warming temperatures and solar radiation are allowing for the continued possibility of human triggered avalanches in sun exposed areas, mainly on steep NE-E-SE aspects.

High pressure has built into the forecast area. Warming air temperatures were observed over the past two days. Solar radiation is intense due to the time of year. Sunny skies are expected to last through the end of the week. A weather system will pass to the north of the forecast area today. This will create a slight increase in cloud cover and cooler temperatures for the forecast area. Ridgetop winds shifted to light westerly overnight and are expected to continue through the day today. Air temperature inversion kept the upper elevations above freezing last night.

Settlement is rapidly occurring within the new snow from Sunday. Yesterday in the Donner Peak area on Donner Pass, good bonding was observed at the interface of the recent storm snow and the uppermost melt-freeze crust within the snowpack. Surface warming instability was evident, beginning with small natural roller balls around 9am. As the day progressed, natural and human triggered roller balls 2-3 feet in diameter were observed on sun exposed NE through E aspects. Some human triggered wet sluff activity was observed in pockets of recently wind loaded snow on steep, sun exposed NE aspects by 11:30am. Melt-freeze snow surface conditions will continue to spread during the next few days. Isolated pockets of soft, unconsolidated snow linger in shaded, wind protected areas.

The bottom line: Warming temperatures and solar radiation are allowing for the continued possibility of human triggered avalanches in sun exposed areas, mainly on steep NE-E-SE aspects.

We are scaling back operations and are no longer issuing avalanche advisories for this season. We will continue to provide weather and snow condition information until we close for the season on April 28th.

Thank you to all of our sponsors, those individuals who purchased tickets for the SAC Ski Day fundraising events, and everyone else who donated funding this winter. We have met our operating budget for this season and have a solid start on next year's funding. For more details about our financial situation please click here.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 36 deg. F
Max. temperature at Sierra Crest past 24 hours: 58 deg. F
Average wind direction at Sierra Crest past 24 hours: easterly shifting to westerly
Average wind speed at Sierra Crest past 24 hours: 15 mph
Maximum wind gust at Sierra Crest past 24 hours: 25 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 60 inches

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Mountain Weather Forecast For Wednesday:
Sunny to partly cloudy skies.
Temperature forecast for 8,000 to 9,000 feet: 38 - 48 degrees F.
Ridgetop winds forecast for the Sierra Crest: Westerly 20 - 30 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 skies with daytime highs 45 to 55 degrees. Tonight, partly cloudy skies with overnight lows 31 to 41 degrees F. North winds at 5 to 15 mph. Thursday, sunny skies with daytime highs 50 to 60 degrees F. Northeast winds at 5 to 15 mph are expected.

Above 8000 Feet:
Today, sunny to partly cloudy skies with daytime highs 38 to 48 degrees. Tonight, partly cloudy skies with overnight lows 31 to 41 degrees F. West winds at 10 to 20 mph. Thursday, sunny skies with daytime highs 45 to 55 degrees F. Northeast winds at 25 to 35 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:
  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.