THIS AVALANCHE ADVISORY EXPIRED ON November 17, 2015 @ 6:41 am
Avalanche Advisory published on November 16, 2015 @ 6:41 am
Issued by Brandon Schwartz - Tahoe National Forest

MODERATE avalanche danger exists today in the majority of areas on slopes 35 degrees and steeper. Wind slabs are a problem on all aspects in near and above treeline areas. Storm slabs remain a problem on NW-N-NE aspects both near and below treeline. Natural avalanches are unlikely. Human triggered avalanches remain possible.

 

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: Wind Slab
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Strong to gale force ridgetop winds out of the SW yesterday shifted to NE overnight. Ongoing redistribution of snow on the ground today is expected to scour some but not all of the wind slabs formed yesterday and create new wind slabs today. This will allow for wind slabs to exist in some locations on all aspects today near and above treeline. Areas of blowing snow, wind pillows, and sastrugi formations will all be helpful indicators in determining the areas of most recent wind loading.

Avalanche Problem 2: Storm Slab
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Storm slabs that exist near treeline and below treeline on NW-N-NE aspects are a lingering avalanche problem today. Shaded, wind protected areas with reasonably well developed near surface facets just below the old/new snow interface remain suspect. Keep in mind that these areas will have a significant draw for recreation today so choose slopes wisely. Slope angle is always the easiest data with which to make decisions. The presence or absence of recently buried near surface facets varies widely across the forecast area. Given the overall shallow snow depths associated with the locations of this avalanche problem, quick hand pits remain an effective tool for searching out cohesive surface snow (slab) on top of softer, faceted snow (weak layer).

recent observations

Observations made yesterday on Castle Peak (Donner Summit area) revealed the presence of small winds slabs in wind loaded areas near treeline and evidence of storm slabs in open areas below treeline. Skier triggered cracking occurred easily while weighting the edges of wind slabs on test slope features. Wind slabs were not observed to extend very far down slope. Evidence of storm slabs was noted on northerly aspects in areas where new snow had deposited on top of fairly well developed near surface facets. Skier triggered cracking extending from the snow surface down into old snow layers was observed. Click here for photos and more info.

Weather and CURRENT CONDITIONS
weather summary

Snowfall totals over the last 24 hours generally came in at the lower end of forecast amounts at 4 to 10 inches. Colder air has moved into the region and winds have shifted to the NE. Expect maximum daytime highs today in the upper teens to mid 20s for areas above 7,000'. NE winds will continue to increase in speed, becoming strong as the morning progresses. Maximum gusts of 80 mph are forecast over the ridgetops today. Wind chill should be rather noticeable. A warming trend with NE winds decreasing to moderate in speed is expected for tomorrow.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 11 to 16 deg. F.
Max. temperature in the last 24 hours: 25 to 32 deg. F.
Average wind direction during the last 24 hours: SW shifting to NE
Average wind speed during the last 24 hours: 38 mph
Maximum wind gust in the last 24 hours: 89 mph
New snowfall in the last 24 hours: 4 to 10 inches
Total snow depth: 12 to 24 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy skies, becoming partly cloudy. Partly cloudy skies. Mostly cloudy skies, becoming partly cloudy.
Temperatures: 20 to 27 deg. F. 13 to 20 deg. F. 35 to 42 deg. F.
Wind Direction: NE NE NE shifting to S in the afternoon.
Wind Speed: 15 to 25 mph with gusts to 40 mph. 15 to 20 mph with gusts to 35 mph. 10 to 15 mph with gusts to 25 mph.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy skies, becoming partly cloudy. Partly cloudy skies. Mostly cloudy skies, becoming partly cloudy.
Temperatures: 17 to 24 deg. F. 13 to 20 deg. F. 33 to 40 deg. F.
Wind Direction: NE NE NE
Wind Speed: 40 to 45 mph with gusts to 70 mph, increasing to 50 to 55 mph with gusts to 80 mph in the afternoon. 40 to 50 mph with gusts to 70 mph. 25 to 30 mph with gusts to 45 mph, decreasing to 15 to 20 mph with gusts to 35 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.