THIS AVALANCHE ADVISORY EXPIRED ON November 30, 2015 @ 6:54 am
Avalanche Advisory published on November 29, 2015 @ 6:54 am
Issued by Brandon Schwartz - Tahoe National Forest

LOW avalanche danger continues for all elevations and aspects. The potential exists for the unlikely triggering of small avalanches in isolated areas. Continue to use accepted best practice travel techniques while traveling in or below avalanche terrain. Keep exposure limited to one person at a time and avoid grouping in avalanche run out zones.

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
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Good snowpack stability exists across much of the forecast area. Isolated pockets of instability remain ongoing mainly near treeline and below treeline on NW-N-NE aspects. In some but not all of these areas, faceted weak layers are found below a slab either at mid height or at the bottom of the snowpack. In areas where this snowpack structure exists, any signs of instability including collapse, whumpfing, or unstable snowpit test results are cause for conservative decision making. The overall snowpack remains less than 2.5 feet deep in most areas so it takes little effort to poke with a pole or intentionally trench a snowmobile across a test slope to have a look for well bonded snow on top of somewhat loose grained facets.

recent observations

Recent observations including those made in the Luther Pass, Pole Creek, Mount Rose, Carson Pass, and Donner Summit areas, all point to a fair amount of spacial variability in the snowpack in near treeline and below treeline areas on NW-N-NE aspects. In some areas faceted weak layers exist. In other locations of similar aspect and elevation these weak layers are notably absent. In areas where these weak layers exist, collapsing, whumphing, and unstable snowpit test results have been observed as recently as Friday. In areas where these weak layers are absent, no obvious signs of instability or unstable snowpit test results have been observed. Strong temperature gradients within the snowpack indicate that faceting will continue in the short term.

Above treeline and on the sun exposed E-SE-S-SW-W aspects conditions are very similar across the forecast area. Pockets of wind scouring and wind drifted snow exist above treeline. Evidence of instability above treeline has been limited to very minor human triggered cracking of wind pillows over the past few days. On the sun exposed and wind protected slopes, a very shallow well anchored snowpack exists with the most recent new snow covering either melt-freeze layering or ground level rocks and vegetation.

Weather and CURRENT CONDITIONS
weather summary

Weak high pressure has built in over the forecast area. Gradual warming will affect the mid and upper elevations over the next few days with maximum daytime air temperatures in the low 20s to low 30s. Inversion conditions will allow cold air to settle down into the mountain valleys each night with overnight lows remaining below average. A weak weather disturbance will bring some cloud cover to the forecast area tomorrow. An isolated snow shower is a remote possibility with no significant accumulation expected.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 7 to 21 deg. F.
Max. temperature in the last 24 hours: 21 to 28 deg. F.
Average wind direction during the last 24 hours: E shifting SW
Average wind speed during the last 24 hours: 16 mph
Maximum wind gust in the last 24 hours: 27 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 18 to 23 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 skies. Clear skies. Partly cloudy skies.
Temperatures: 23 to 30 deg. F. 5 to 15 deg. F. 28 to 30 deg. F.
Wind Direction: Variable Variable SW
Wind Speed: Light winds Light winds Light winds increasing to 10 to 15 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Sunny skies. Clear skies. Partly cloudy skies.
Temperatures: 21 to 28 deg. F. 9 to 15 deg. F. 26 to 33 deg. F.
Wind Direction: Variable W W
Wind Speed: Light winds 10 to 15 mph. Gusts up to 25 mph in the evening. 15 to 20 mph with gusts to 30 mph.
Expected snowfall: 0 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.