THIS AVALANCHE ADVISORY EXPIRED ON March 28, 2016 @ 6:45 am
Avalanche Advisory published on March 27, 2016 @ 6:45 am
Issued by Brandon Schwartz - Tahoe National Forest

Early this morning, LOW avalanche danger exists for all elevations and aspects. Areas of MODERATE avalanche danger are expected to form in response to daytime warming on E-SE-S-SW-W aspects at all elevations and on NW-N-NE aspects below 8,000' to 8,500'. Loose wet avalanches are possible today. Avalanche size could be large enough to bury a person, especially if a terrain trap is involved.

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
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    Very Likely
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    Large
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A decent snow surface refreeze is expected to have occurred last night, mostly the result of radiational cooling under clear skies. Air temperatures at 5:30 am this morning were in the mid to upper 30s for most locations. A few upper elevation stations in the 8,000' to 9,700' range were reporting air temperatures in the 29 to 31 degree range. Winds out of the SW last night kept air temperature inversion conditions to a minimum.

Rapid warming is expected this morning. There is some uncertainty as to how much cloud cover will exist over the forecast area this afternoon. If skies remain sunny into the afternoon hours, areas of loose wet snow instability will form. If significant cloud cover develops and is able to slow the rate of snow surface melt before last night's melt-freeze crust loses supportability, then fewer areas of loose wet instability will form today.

Monitor the strength of the melt-freeze crust, just below any surface wet snow by paying attention to the depth of penetration of boots and equipment into the upper snowpack. Once last night's refreeze melts away and boots and equipment easily penetrate into the deep wet snow below, it is time to vacate avalanche terrain. The vast majority of wet snow instability is expected on E-SE-S-SW-W aspects at all elevations and on NW-N-NE aspects below 8,000' to 8,500'. In these areas, loose wet avalanches are possible today. Timing travel in avalanche terrain is critical. When dealing with wet snow instability, the difference between a stable and unstable slope can be as little as 15 minutes worth of additional melt. Late starts for travel in avalanche terrain on warm sunny spring days are not advised.

recent observations

Observations made yesterday from Waterhouse Peak (Luther Pass area) and received from terrain adjacent to Donner Pass revealed surface wet snow formation at all elevations on E-SE-S-SW-W aspects and on NW-N-NE aspects below 8,300'. By mid day, areas of deep wet snow with marginal skier supportability were observed on E-SE-S aspects of Waterhouse Peak below 9,300'. Snowpit data collected from N aspects at 9,450' on Waterhouse Peak and from 7,100' on Donner Pass revealed no signs of instability. At the snowpit location on Waterhouse Peak, the near surface snowpack had yet to undergo a melt cycle.

 

Weather and CURRENT CONDITIONS
weather summary

Following another warm day today, a significant change in the weather will occur tonight. Cold front passage is forecast to decrease maximum daytime air temperatures by 15 to 20 degrees from today to tomorrow. Increasing SW winds ridgetop winds are expected this afternoon and evening ahead of the approaching weather system. Snow showers are expected to develop tonight and last into early this week.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 31 to 37 deg. F.
Max. temperature in the last 24 hours: 47 to 52 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 18 mph
Maximum wind gust in the last 24 hours: 24 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 75 to 114 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Sunday Sunday Night Monday
Weather: Sunny to partly cloudy skies, eventually becoming mostly cloudy. Mostly cloudy skies with a slight chance of snow showers after midnight. Cloudy skies, becoming mostly cloudy. Scattered snow showers.
Temperatures: 42 to 48 deg. F. 20 to 25 deg. F. 25 to 30 deg. F.
Wind Direction: SW SW NW
Wind Speed: 10 to 15 mph with gusts to 25 mph, increasing to 25 to 30 mph with gusts to 40 mph in the afternoon. 20 to 30 mph with gusts to 45 mph. 15 to 20 mph with gusts to 30 mph.
Expected snowfall: 0 in. Up to 1 in. 1 to 4 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Sunny to partly cloudy skies, eventually becoming mostly cloudy. Mostly cloudy skies with a slight chance of snow showers after midnight. Cloudy skies, becoming mostly cloudy. Scattered snow showers.
Temperatures: 37 to 42 deg. F. 15 to 20 deg. F. 20 to 25 deg. F.
Wind Direction: W SW W to NW
Wind Speed: 15 to 20 mph with gusts to 30 mph, increasing to 35 to 40 mph with gusts to 60 mph in the afternoon. 35 to 45 mph with gusts to 65 mph. 30 to 35 mph with gusts to 55 mph, decreasing to 15 to 20 mph with gusts to 30 mph in the afternoon.
Expected snowfall: 0 in. Up to 1 in. 2 to 6 in.
Disclaimer

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.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258