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 March 21, 2007:

March 21, 2007 at 0:00 am

Forecast Discussion:

This advisory was posted on Wednesday, March 21th, 2007 at 6:57 am

The bottom line: North of Hwy 50, avalanche danger is LOW for all elevations and aspects. South of Hwy 50, avalanche danger is MODERATE in wind loaded areas near and above treeline on SW-W-NW aspects 35 degrees and steeper. Below treeline, avalanche danger is MODERATE in open areas 37 degrees and steeper.

The weak weather system that impacted the forecast area yesterday is dissipating and moving off to the east. Some lingering snow showers will persist this morning, lasting into the afternoon in the southern half of the forecast area. Ridgetop winds shifted to easterly overnight and are strong enough to move snow. Air temperatures are expected to remain cooler today, with below freezing maximum daytime air temperatures forecast for the upper elevations.

North of Hwy 50, a trace to 2 inches of new snow has been observed. The snowpack will remain mostly frozen today with no areas of snowpack instability expected. Only the top 1-2 inches of the snowpack are expected to soften below 8,000'. Above 8,000', minimal to no softening of the snow surface is expected. This will help the deeper snowpack to continue to refreeze after the prolonged period of above freezing temperatures observed last week.

South of Hwy 50, up to 7 inches of new snow have fallen since yesterday afternoon with continued snow shower activity this morning. East winds are eroding snow deposited yesterday in N-NE-E aspect avalanche start zones above treeline. Redistribution of this snow onto SW-W-NW aspects will occur as east winds continue. This will create shallow slabs in wind loaded areas above treeline on SW-W-NW aspects that will be prone to human triggering today. These slabs will be less than 1 foot deep. Below treeline, new snow sits on top of a hard melt-freeze crust. This will provide a bed surface for human triggered sluff activity today in open areas 37 degrees and steeper. Natural avalanche activity is unlikely today.

The bottom line: North of Hwy 50, avalanche danger is LOW for all elevations and aspects. South of Hwy 50, avalanche danger is MODERATE in wind loaded areas near and above treeline on SW-W-NW aspects 35 degrees and steeper. Below treeline, avalanche danger is MODERATE in open areas 37 degrees and steeper.

At this time, SAC is still short $1,700 in operating funds for this season and we have no money with which to start next season. Our next fundraiser is this Sunday, March 25th at Sugar Bowl Ski Area. We are selling $30 lift tickets that have been donated to us by Sugar Bowl. All proceeds from each ticket sale go directly to our operating budget. Tickets are only available online through Snowbomb.com. Tickets can be easily obtained up to the night before the event. Click here to purchase your lift ticket. Come on out and join us for wonderful day of spring sun on the deck, corn snow on the slopes, and a gear raffle from Backcountry Access, Black Diamond, and Patagonia. We are very appreciative of the financial support already received this winter from a variety of users. If you have not yet shown your financial support for us this winter, please do so!

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 20 deg. F
Max. temperature at Sierra Crest past 24 hours: 33 deg. F
Average wind direction at Sierra Crest past 24 hours: Westsouthwesterly, shifting to easterly
Average wind speed at Sierra Crest past 24 hours: 30 mph
Maximum wind gust at Sierra Crest past 24 hours: 56 mph
New snow fall at 8,200 feet past 24 hours: 1-7 inches
Total snow depth at 8,200 feet: 69 inches

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Mountain Weather Forecast For Today:
Partly cloudy with morning snow showers and afternoon clearing.
Temperature forecast for 8,000 to 9,000 feet: 27 to 32 degrees F.
Ridgetop winds forecast for the Sierra Crest: Easterly 30-40 mph, G 50 mph.
Snowfall expected in the next 24 hours: 0-2 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet:
Today, partly cloudy with snow showers in the morning and afternoon clearing. Daytime highs 30 to 35 degrees F. Northeast winds at 10 to 20 mph with gusts to 30 mph. Tonight, clear skies with overnight lows 22 to 27 degrees F. Northeast winds at 10 to 20 mph. Thursday, partly cloudy with daytime highs 40 to 45 degrees F. Northeast winds at 5 to 15 mph are expected.

Above 8000 Feet:
Today, partly cloudy with snow showers in the morning and afternoon clearing. Daytime highs 27 to 32 degrees F. Northeast winds at 25 to 35 mph with gusts to 50 mph. Tonight, clear skies with overnight lows 22 to 27 degrees F. Northeast winds at 25 to 35 mph with gusts to 60 mph. Thursday, partly cloudy with daytime highs 37 to 42 degrees F. Northeast winds at 10 to 20 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.