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 advisory was posted on Friday, April 20th, 2007 at 6:40 am

The bottom line: Near and above treeline, avalanche danger is LOW with very isolated pockets of MODERATE danger on wind loaded SW-W-NW aspects 37, degrees and steeper. Below treeline, avalanche danger is LOW.

The weather system that is currently over the forecast area has lost strength overnight. Cloud cover and a few scattered snow showers are all that is expected from this system today. Ridgetop winds shifted to moderate easterly overnight and are expected to continue through the day today. Maximum daytime air temperatures are expected to climb a few degrees over yesterday's highs, but significant a warming event is not expected. Another weather system creating rain and snow is expected to impact the forecast area late Saturdat night/early Sunday morning.

Yesterday on Mt. Judah near Donner Pass, very small and isolated pockets of instability were observed just below ridgelines on wind loaded NE-E aspects near and above treeline. Wind loading was affecting only the top few feet of avalanche start zones. Any observed human triggered avalanche activity was very small, stopping a few feet from where it started. The largest triggered soft slab measured 10 feet wide and 6 feet down slope. Soft slabs and sluff activity occurred 2-4 inches deep and did not include sufficient snow to present a significant hazard to backcountry travelers. Human triggered snowpack failure was limited to avalanche start zones 39 degrees and steeper.

Easterly ridgetop winds that occurred overnight are expected to have scoured new snow from avalanche start zones on N-NE-E aspects and redistributed it onto SW-W-NW aspects. Some very shallow and very isolated pockets of new soft slab formation are expected today on SW-W-NW aspects. Any instability will be limited to areas where a smooth old snow surface exists below the new wind loading. Areas where blowing snow is deposited onto bare ground will not exhibit snowpack instability today.

Natural avalanche activity is unlikely today. Any snowpack instability is expected to occur only in response to human triggering. Any avalanche activity that does occur today is expected as very small, isolated soft slabs and loose snow sluffs in heavily wind loaded areas. Near and above treeline areas on steep and wind loaded SW-W-NW aspects where an old snow surface and poor anchoring exist, are the most susceptible to human triggered avalanche activity today.

The bottom line: Near and above treeline, avalanche danger is LOW with very isolated pockets of MODERATE danger on wind loaded SW-W-NW aspects 37, degrees and steeper. Below treeline, avalanche danger is LOW.

We are working with a very limited number of observations at this time of year. Due to decreased numbers of observations and waning backcountry interest, we will begin to scale back operations this Sunday, April 22nd. We plan to end operations 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): 17 deg. F
Max. temperature at Sierra Crest past 24 hours: 25 deg. F
Average wind direction at Sierra Crest past 24 hours: westsouthwesterly shifting to easterly
Average wind speed at Sierra Crest past 24 hours: 29 mph
Maximum wind gust at Sierra Crest past 24 hours: 50 mph
New snow fall at 8,200 feet past 24 hours: trace - 2 inches
Total snow depth at 8,200 feet: 58 inches

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Mountain Weather Forecast For Today:
Mostly cloudy with scattered snow showers
Temperature forecast for 8,000 to 9,000 feet: 28 - 34 degrees F.
Ridgetop winds forecast for the Sierra Crest: Easterly 15 - 25 mph, gusting to 40 mph.
Snowfall expected in the next 24 hours: trace - 2 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet:
Today, mostly cloudy with isolated snow showers. Snow accumulation up to 1 inch. Daytime highs 34 to 39 degrees F. Northeast winds at 10 to 15 mph. Tonight, mostly cloudy skies with isolated snow showers in the evening. Overnight lows 21 to 26 degrees F. Northwest winds at 10 to 15 mph. Saturday, mostly cloudy with a slight chance of snow showers late in the afternoon. Daytime highs 38 to 46 degrees F. Southwest winds at 10 to 20 mph, gusting to 30 mph in the afternoon are expected.

Above 8000 Feet:
Today, mostly cloudy with isolated snow showers. Snow accumulation up to 2 inches. Daytime highs 28 to 34 degrees F. Northeast winds at 10 to 20 mph with gusts to 40 mph in the morning. Tonight, mostly cloudy skies with isolated snow showers in the evening. Overnight lows around 21 degrees F. North winds at 10 to 20 mph. Saturday, mostly cloudy with a slight chance of snow showers late in the afternoon. Daytime highs 35 to 41 degrees F. Southwest winds at 15 to 25 mph, increasing to 20 to 30 mph with gusts to 60 mph in the afternoon 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:
	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.