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 Sunday, February 18th, 2007 at 6:51 am

The bottom line: Avalanche danger is LOW for all elevations and aspects. Some very small and isolated pockets of shallow surface instability may form late this afternoon in heavily wind loaded areas. These areas are not expected to present a hazard to backcountry travelers during the next 24 hours.

A weak weather system is passing to the north of the forecast area today. This is expected to cause a few isolated snow showers this morning and more widespread snow showers late this afternoon and evening. Air temperatures will remain warm this morning before cold front passage occurs this afternoon, causing air temperatures to decrease. Southwesterly ridgetop winds began late yesterday afternoon and are expected to increase during the day today. Clearing skies and easterly ridgetop winds are expected on Monday.

Warm temperatures over the past few days have created melt-freeze surface conditions on all aspects below 9,000'. Melt-freeze conditions were observed yesterday up to 10,000' on southerly aspects with colder, non-melted but wind affected snow surfaces on northerly aspects. Avalanche start zones above 9,000' on N-NE-E aspects experienced significant wind scouring on Saturday from east winds. These same aspect start zone below 9,000' experienced only cornice erosion due to the onset of melt-freeze conditions prior to the east wind event. Continued strengthening of the snowpack has been observed during the past week.

Layer bonding tests are showing excellent bonding within the recent storm snow. Observation of hard test results continues to occur on persistent faceted snow crystals near the base of the snowpack. Overall, the existing snowpack is stable at this time. Minimal new snowfall amounts today and this evening of 1-2 inches may create some very small and shallow pockets of surface instability in heavily wind loaded areas. This areas will be most prominent above treeline on N-NE-E aspects, 35 degrees and steeper. These areas of instability are not expected to present a hazard to backcountry travelers during the next 24 hours.

No avalanche activity from yesterday was observed or reported.

The bottom line: Avalanche danger is LOW for all elevations and aspects. Some very small and isolated pockets of shallow surface instability may form late this afternoon in heavily wind loaded areas. These areas are not expected to present a hazard to backcountry travelers during the next 24 hours.

At this time, we have not raised enough money to meet our operating budget for this year. If you use this service with any regularity and would like to continue to do so, please show your 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 financial graph showing the current fundraising and budget numbers 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): 30 deg. F
Max. temperature at Sierra Crest past 24 hours: 46 deg. F
Average wind direction at Sierra Crest past 24 hours: easterly, shifting to southwesterly
Average wind speed at Sierra Crest past 24 hours: 29 mph
Maximum wind gust at Sierra Crest past 24 hours: 71 mph
New snow fall at 8,200 feet past 24 hours: 1 - 2 inches
Total snow depth at 8,200 feet: 51 inches

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Mountain Weather Forecast For Today:
Cloudy skies with snow showers, cooling in the afternoon.
Temperature forecast for 8,000 to 9,000 feet: 38 - 44 deg. F, falling to around 30 deg. F in the afternoon
Ridgetop winds forecast for the Sierra Crest: westsouthwesterly 25 - 40 mph, gusting to 70 mph
Snowfall expected in the next 24 hours: 1- 2 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
Today, cloudy skies with isolated snow showers in the morning, becoming widespread in the afternoon. Snow level 6,500' lowering to 6,000' in the afternoon. Snow accumulation 1 inch. Daytime highs 41 to 47 degrees F, falling to the 30s in the afternoon. Southwest winds at 15 to 25 mph, gusting 35 to 40 mph. Tonight, mostly cloudy with scattered snow showers in the evening and isolated showers after midnight. Lows 20 to 25 degrees F. West winds at 10 to 20 mph, shifting to north winds 10 to 15 mph by midnight. Monday, partly cloudy skies with daytime highs 34 to 39 degrees F. Northeast winds at 10 to 20 mph, diminishing in the afternoon are expected.

Above 8000 Feet
Today, cloudy skies with isolated snow showers in the morning, becoming widespread in the afternoon. Snow accumulation 1 to 2 inches. Daytime highs 38 to 41 degrees F, falling to around 30 degrees in the afternoon. Westsouthwest winds at 25 to 40 mph, gusting to 70 mph. Tonight, mostly cloudy with scattered snow showers in the evening and isolated showers after midnight. Lows 17 to 22 degrees F. West winds at 15 to 25 mph, shifting to north by midnight. Monday, partly cloudy skies with daytime highs 28 to 34 degrees F. East winds at 20 to 30 mph with gusts to 40 mph are expected in the morning. Winds are expected to decrease 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:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.