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 April 12, 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. MODERATE danger will develop on E-SE-S-SW-W aspects and on other aspects where pockets of unconsolidated snow linger on slopes steeper than 38 degrees due to daytime warming.

The high pressure ridge is now well established over the forecast area. Winds should become light by this afternoon before shifting to the south and southwest tomorrow ahead of a low pressure trough. The forecast calls for this weekend to be the warmest few days of the year so far with highs reaching into the upper 50's above 8000 ft and low 60's between 7000 and 8000 ft. Remote sensors along the Sierra Crest indicate that the ridgetop temperatures never fell below freezing last night and most sensors were already reporting temperatures around 39 degrees F. by 5 am this morning.

Warmer air temperatures, intense solar radiation, and a weaker overnight refreeze will cause more rapid and more extensive melting and allow will free water to form deeper in the snowpack today. On southerly aspects, where well established melt water channels have formed in the snowpack over the last 6 weeks, drainage should help limit the weakening of the snowpack. 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 today for human triggerable wet snow sluffs and pinwheels to occur on any steep sun exposed aspects. The weaker overnight refreeze, warmer temperatures, and intense sun will make these instabilities larger and more widespread. Wet slab avalanche activity should be unlikely today; however it is possible especially where the snowpack sits on an impermeable ground surfaces like a slabs of granite. 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 of surface wet snow instabilities 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. MODERATE danger will develop on E-SE-S-SW-W aspects and 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): 39 deg. F
Max. temperature at Sierra Crest past 24 hours: 46 to 52 deg. F.
Average wind direction at Sierra Crest past 24 hours: East northeast
Average wind speed at Sierra Crest past 24 hours: 20 mph
Maximum wind gust at Sierra Crest past 24 hours: 69 mph
New snowfall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 72 inches
Mountain Weather Forecast For Today:
Sunny and warmer.
Temperature forecast for 8,000 to 9,000 feet: 48 to 54 deg. F
Ridgetop winds forecast for the Sierra Crest: East at 10 to 20 mph becoming light 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 54 to 62 deg. F. East winds at 10 mph becoming light in the afternoon.

Tonight, clear skies with overnight lows 38 to 44 deg. F. and light winds.

For Sunday, sunny skies with daytime highs 58 to 66 deg. F. Southwest winds at 10 mph.

Above 8000 Feet:

Today, sunny skies with daytime highs 48 to 54 deg. F. East winds at 10 to 20 mph becoming light in the afternoon.

Tonight, clear skies with overnight lows 38 to 43 deg. F. South winds at 10 mph.

For Sunday, sunny skies with daytime highs 52 to 58 deg. F. South winds at 10 mph becoming southwest at 15 to 20 mph with gusts to 35 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:
	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.