THIS AVALANCHE ADVISORY EXPIRED ON December 22, 2016 @ 6:47 am
Avalanche Advisory published on December 21, 2016 @ 6:47 am
Issued by Brandon Schwartz - Tahoe National Forest

LOW avalanche danger exists for all elevations. Isolated old wind slabs may linger in near and above treeline terrain. Normal caution is advised.

1. Low

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Above Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Normal Caution
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  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

The 0 to 1 inch of new snow last night was insufficient to create new avalanche problems. The focus remains on old lingering wind slabs that are becoming increasingly difficult to trigger. Complex terrain in and around chutes and cliff bands is the type of terrain where instability tends to linger the longest. Signs of lingering instability preceding any human triggered avalanche activity that occurs today may not be obvious. Minimize risk by traveling one at a time on or under steep slopes, not grouping up in runout zones, and not relying on marginal islands of safety.

recent observations

Observations made yesterday on Tamarack Peak (Mount Rose area) and in the Meiss Headwaters (Carson Pass area) revealed both near crust facets forming above the Dec 15 rain crust at the base of the recent storm snow and near surface facets forming within the recent storm snow. This matches well with other observations gathered over the past several days. Observations have indicated that faceting is most prevalent in wind protected, shaded areas especially between 8,500' and 9,000', but has been observed to exist between 8,000' and 9,500' around the forecast area. Locations that hold 3 inches to 1 foot of recent storm snow on top of the Dec 15 rain crust seem to have the most well developed facets. Snowpit tests have indicated that this combination of faceted weak layer above the crust and overlying slab of recent storm snow is unlikely to sustain propagation in its current state. This could easily change with new snow loading.

Weather and CURRENT CONDITIONS
weather summary

The weak weather system that gave a dusting of new snow to isolated portions of the forecast area last night is moving off to the east. Short lived high pressure will build in over the forecast area this afternoon, lasting through Thursday. Ridgetop winds shifted from the SW to the ENE overnight in response to the departing weather system. As high pressure builds, winds are forecast to decrease from moderate speed to light to moderate speed this afternoon. Tomorrow, winds are forecast to shift back to the SW ahead of an approaching storm system expected to arrive Friday. See the NWS Winter Storm Watch for more info on this approaching storm.

 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 25 to 30 deg. F.
Max. temperature in the last 24 hours: 38 to 48 deg. F.
Average wind direction during the last 24 hours: SW shifting to ENE
Average wind speed during the last 24 hours: SW 10 mph | ENE 20 mph
Maximum wind gust in the last 24 hours: SW 18 mph | ENE 35 mph
New snowfall in the last 24 hours: 0 to 1 inches
Total snow depth: Along the Sierra Crest: 18 to 32 inches | In the Mt. Rose area: 52 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy skies, becoming partly cloudy. Scattered snow showers in the morning. Clear skies. Partly cloudy skies.
Temperatures: 34 to 39 deg. F. 19 to 25 deg. F. 39 to 44 deg. F.
Wind Direction: E Variable SW
Wind Speed: 10 to 15 mph with gusts to 30 mph in the morning, becoming light. Light winds Generally light winds. Gusts to 25 mph in the afternoon.
Expected snowfall: 0 to 1 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy skies, becoming partly cloudy. Scattered snow showers in the morning. Clear skies. Partly cloudy skies.
Temperatures: 31 to 37 deg. F. 20 to 25 deg. F. 36 to 41 deg. F.
Wind Direction: E S SW
Wind Speed: 10 to 15 mph with gusts to 40 mph. Gusts decreasing to 30 mph in the afternoon. 10 to 15 mph with gusts to 35 mph. 10 to 15 mph with gusts to 40 mph.
Expected snowfall: 0 to 1 in. 0 in. 0 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