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 22, 2007:


March 22, 2007 at 0:00 am

Forecast Discussion:


This advisory was posted on Thursday, March 22nd, 2007 at 6:51 am

The bottom line: South of Hwy 88, pockets of MODERATE avalanche danger will develop below treeline on all aspects 35 degrees and steeper as daytime warming occurs. For all other areas, avalanche danger is LOW for all elevations and aspects.

High pressure has built back into the forecast area this morning. Sunny skies and gradually warming air temperatures with continued easterly winds are expected today. Easterly ridgetop winds became strong yesterday afternoon and will continue this morning before becoming light this afternoon. Well below freezing overnight temperatures at the mid and upper elevations have been observed for the past two nights. A short lived warming trend is expected through the weekend before a potentially large storm system is forecasted to impact the area Monday night and Tuesday.

Below treeline, air and snow surface temperatures will warm as the day progresses. South of Hwy 88, up to 7 inches of new snow fell Wednesday afternoon and evening onto a frozen crust surface. Human triggered wet snow avalanches are possible today in wind protected areas below treeline, especially in the 7,000' to 8,000' elevation range. The combination of new snow, warming air temperatures, and a high density bed surface will create pockets of ideal conditions for human triggered avalanches below treeline in open areas 35 degrees and steeper. Areas of human triggered roller ball and pinwheel activity should be expected. Strong easterly winds this morning will limit the rate of warming air temperatures today. This is expected to keep any human triggered avalanche activity below treeline limited to pockets of terrain where the exact mix of factors contributing to instability occur simultaneously.

Colder air temperatures and a solid snowpack refreeze occurring the past two nights have helped to increase the overall stability of the snowpack near and above treeline. Above treeline, strong easterly ridgetop winds scoured any new snow from N-NE-E aspect avalanche start zones and redistributed it as very shallow slabs on SW-W-NW aspects. These new slabs are very small and shallow and are not expected to be very reactive today. Decreased wind loading rates occurred yesterday afternoon as less snow became available for wind transport, allowing these slabs to stabilize. Human triggering of shallow slab avalanches above treeline are unlikely today, but not impossible on steep wind loaded SW-W-NW aspects south of Hwy 88.

The bottom line: South of Hwy 88, pockets of MODERATE avalanche danger will develop below treeline on all aspects 35 degrees and steeper as daytime warming occurs. For all other areas, avalanche danger is LOW for all elevations and aspects.

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): 22 deg. F
Max. temperature at Sierra Crest past 24 hours: 34 deg. F
Average wind direction at Sierra Crest past 24 hours: Easterly
Average wind speed at Sierra Crest past 24 hours: 53 mph
Maximum wind gust at Sierra Crest past 24 hours: 86 mph
New snow fall at 8,200 feet past 24 hours: trace inches
Total snow depth at 8,200 feet: 68 inches

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Mountain Weather Forecast For Today:
Sunny skies.
Temperature forecast for 8,000 to 9,000 feet: 35 to 40 degrees F.
Ridgetop winds forecast for the Sierra Crest: Easterly 40-50 mph, G 70 mph, decreasing in the afternoon.
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet:
Today, sunny skies with daytime highs 40 to 45 degrees F. Northeast winds at 5 to 15 mph with gusts to 25 mph. Tonight, partly cloudy skies with overnight lows 24 to 32 degrees F. North winds at 5 to 10 mph. Friday, sunny skies with daytime highs 42 to 47 degrees F. North winds at 15 to 20 mph are expected.

Above 8000 Feet:
Today, sunny skies with daytime highs 35 to 40 degrees F. Northeast winds at 30 to 40 mph with gusts to 70 mph in the morning. East winds decreasing to 15 to 25 mph in the afternoon. Tonight, partly cloudy skies with overnight lows 26 to 32 degrees F. North winds at 15 to 25 mph. Friday, sunny skies with daytime highs 38 to 43 degrees F. North 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:

  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.