THIS AVALANCHE ADVISORY EXPIRED ON November 18, 2015 @ 6:31 am
Avalanche Advisory published on November 17, 2015 @ 6:31 am
Issued by Brandon Schwartz - Tahoe National Forest

Pockets of MODERATE avalanche danger exist above treeline on all aspects on slopes 35 degrees and steeper due to lingering wind slabs. Near treeline and below treeline avalanche danger is LOW on all aspects. Isolated areas of unstable wind slab may remain near treeline, especially in complex terrain. LOW danger means that human triggered avalanches have become unlikely and areas of instability are isolated, not that avalanches will not occur.

 

2. Moderate

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

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.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Strong winds first from the SW, then from the NE over the past 48 hours created visible blowing snow over the high terrain. Significant redistribution of snow on the ground has occurred since the storm. Wind scouring has occurred in many areas near treeline and above treeline on N-NE-E aspects. Pockets of wind slab have been left behind, especially in complex terrain in gullies and around rock buttresses. New wind slabs have formed on SE-S-SW-W-NW aspects. Keep in mind that after the recent winds, if a near treeline or above treeline area looks nicely filled in, it is likely a wind slab. Keep early season excitement in check and fully evaluate conditions before committing.

advisory discussion

If any of the coldest, shadiest, most wind protected N-NE aspects still hold storm slab instability near or below treeline it will be very isolated instability, not warranting specific mention of storm slabs as an avalanche problem. In terms of snowpack evaluation, lingering storm slabs will present as cohesive recent new snow on top of and poorly bonded to older near surface faceted snow below.

recent observations

Observations made yesterday on Tamarack Peak (Mount Rose area) showed significant amounts of blowing snow, wind scouring, and redistribution of snow on the ground. Remote sensors across the forecast area are indicating around 2 inches of settlement has occurred within the recent storm snow in wind protected areas. This settlement, recent snowpit tests, informal observations, and time for recent new snow to bond to the often faceted old snow surface has reduced concerns for storm slabs.

Weather and CURRENT CONDITIONS
weather summary

A warming trend is expected over the next several days. Air temperature inversions will set up keeping minimum overnight air temperatures significantly colder on the mountain valley floors than on the surrounding peaks. Ridgetop winds remain out of the NE this morning but have decreased from strong to moderate in speed. Expect winds to become light at the mid elevations today but continue over the upper elevations. Periods of moderate to strong NW winds are forecast for tonight and tomorrow over the upper elevations.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 26 to 29 deg. F.
Max. temperature in the last 24 hours: 28 to 33 deg. F.
Average wind direction during the last 24 hours: NE
Average wind speed during the last 24 hours: 36 mph
Maximum wind gust in the last 24 hours: 62 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 10 to 22 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Tuesday Tuesday Night Wednesday
Weather: Partly cloudy skies. Partly cloudy skies. Sunny skies.
Temperatures: 38 to 45 deg. F. 25 to 31 deg. F. 42 to 49 deg. F.
Wind Direction: NE shifting to SE in the afternoon. W W shifting to N in the afternoon.
Wind Speed: 10 to 15 mph with gusts to 25 mph. 10 to 15 mph with gusts to 25 mph. 15 to 20 mph with gusts to 30 mph.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Tuesday Tuesday Night Wednesday
Weather: Partly cloudy skies. Partly cloudy skies. Sunny skies.
Temperatures: 35 to 42 deg. F. 21 to 28 deg. F. 39 to 46 deg. F.
Wind Direction: N NW NW
Wind Speed: 20 to 30 mph with gusts to 45 mph. 30 to 40 mph with gusts to 55 mph. 40 to 55 mph with gusts to 65 mph, decreasing to 25 to 30 mph with gusts to 45 mph in the afternoon.
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.