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 Thursday, April 19th, 2007 at 7:00 am

The bottom line: Near and above treeline, avalanche danger is LOW with very isolated pockets of MODERATE danger on recently wind loaded N-NE-E-SE aspects 37, degrees and steeper. Below treeline, avalanche danger is LOW.

Another weak and splitting weather system will impact the forecast area today. Increasing cloud cover and light snowfall are expected as the day progresses. Ridgetop winds remained moderate westerly to northwesterly through the day yesterday, before shifting to easterly for a few hours overnight. Ridgetop winds have shifted to light to moderate southwesterly this morning. Yesterday, maximum daytime air temperatures were in the low to mid 20s in areas above 8,000'. Air temperatures are expected to warm a few degrees over yesterday's highs, but significant warming is not expected today.

New snow accumulations of 4-8 inches have been observed around the forecast area over the past two days. The greatest snowfall amounts have been observed along the Sierra Crest north of Hwy 50. Blowing snow has created drifts up to 3 feet deep in the most heavily wind loaded above treeline areas along the Sierra Crest. Some very small human triggered avalanches were reported yesterday in Blackwood canyon in response to high marking snowmobiles. Very little information is known about this instability. 8 inches of new snow was reported in the area.

Observations in the Mount Rose area showed minimal wind loading, affecting only the top few feet of avalanche start zones on NE-E-SE aspects. No cracking or propagation was observed in response to human triggered cornice collapse into avalanche paths. Weight testing on wind loaded test slopes yielded no failures. Fair bonding was observed at the old/new snow interface with around 4 inches of new snow and very small wind loaded pockets to 1.5 feet deep, limited to areas just below ridgelines.

Natural avalanche activity is unlikely today. Any lingering snowpack instability is expected to occur only in response to human triggering. Any avalanche activity that occurs 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 N-NE-E-SE aspects remain the most susceptible to the possibility of human triggered avalanche activity today.

The bottom line: Near and above treeline, avalanche danger is LOW with very isolated pockets of MODERATE danger on recently wind loaded N-NE-E-SE 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 who purchased tickets for the SAC Ski Day fundraiser 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

--------------------------------------------------------------------------------

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 14 deg. F
Max. temperature at Sierra Crest past 24 hours: 24 deg. F
Average wind direction at Sierra Crest past 24 hours: variable westerly
Average wind speed at Sierra Crest past 24 hours: 20 mph
Maximum wind gust at Sierra Crest past 24 hours: 47 mph
New snow fall at 8,200 feet past 24 hours: trace - 2 inches
Total snow depth at 8,200 feet: 59 inches

--------------------------------------------------------------------------------
Mountain Weather Forecast For Today:
Cloudy with light snow
Temperature forecast for 8,000 to 9,000 feet: 24 - 30 degrees F.
Ridgetop winds forecast for the Sierra Crest: Southwest 20 - 30 mph, gusting to 40 mph.
Snowfall expected in the next 24 hours: 1 to 4 inches

--------------------------------------------------------------------------------
2 Day Mountain Weather Forecast:
7000 to 8000 Feet:
Today, cloudy with isolated snow showers in the morning, then light snow in the afternoon. Daytime highs 30 to 36 degrees F. South winds 10 to 20 mph with gusts to 30 mph. Winds shifting to southwest in the afternoon. Tonight, mostly cloudy skies with snow likely in the evening. Scattered snow showers after midnight. Snow accumulation up to 2 inches. Overnight lows 19 to 24 degrees F. Southwest winds at 10 to 20 mph, shifting to southeast after midnight. Friday, mostly cloudy with a chance of snow showers. Snow accumulation up to 2 inches. Daytime highs 34 to 42 degrees F. Northeast winds 10 to 15 mph are expected.

Above 8000 Feet:
Today, cloudy with isolated snow showers in the morning, then light snow in the afternoon. Snow accumulation up to 2 inches. Daytime highs 24 to 30 degrees F. South winds 15 to 25 mph becoming southwest 20 to 30 mph with gusts to 40 mph by afternoon. Tonight, mostly cloudy skies with snow likely in the evening. Scattered snow showers after midnight. Snow accumulation up to 2 inches. Overnight lows around 18 degrees F. Southwest winds at 15 to 25 mph with gusts to 35 mph, shifting to southeast after midnight. Friday, cloudy with a chance of snow showers. Snow accumulation up to 2 inches. Daytime highs 31 to 37 degrees F. Northeast winds 10 to 15 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:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.