Avalanche Advisory published on February 20, 2018 @ 6:48 am
This Avalanche Advisory expires in 1 hours, 16 minutes
This advisory is valid for 24 hours
Issued by Steve Reynaud - Tahoe National Forest

Moderate avalanche danger will exist in near and above treeline terrain due to a wind slab avalanche problem.  Low avalanche danger will exist in below treeline areas.  Look for unstable snow in wind loaded terrain. 

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.

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
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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
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    Very Large
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Wind slabs will continue to be possible on all aspects in near and above treeline terrain.  Strong to gale force SW winds were followed by moderate to strong NW and NE winds yesterday.  W winds are forecasted this morning before becoming light later today.  Wind slabs are mostly expected to be small, but in areas that received the higher end of storm totals wind slabs could be large enough to injure or bury a backcountry user.

Look for snow surface clues, cornice formation, and wind pillows as to where wind slabs may have formed.  Many exposed areas have been scoured down to firm crusts by the recent winds.  Newly formed cornices may be sensitive to the weight of a backcountry user.

recent observations

* 6 to 8'' of storm snow was reported on Tamarack Peak (Mt. Rose area) yesterday with an additional 1 to 2'' of snow throughout the day.  Small wind slabs were found in wind loaded terrain with localized cracking.  Overall wind slab instability was limited in this area.

* Reports from Andesite Peak (Donner Summit area) reported 4 to 6'' of new snow with minor wind slab activity.

* Moderate to strong NW and NE winds scoured exposed areas and created small wind slabs and cornice formation on SE-S-SW aspects.

* Thin snow cover conditions exist throughout the forecast area on all aspects at lower elevations. Thin snow cover or bare ground exists on most sun-exposed aspects at all elevations.

Weather and CURRENT CONDITIONS
weather summary

Cold low pressure will remain over our area this week with well below average temperatures.  Highs will be in the teens to low 20's above 7000' with decreasing winds into Wednesday.  Light convective snow showers could be possible in isolated areas.  Another storm is expected Wednesday night into Thursday that will be similar to our last storm. 

The high pressure that has been off the west coast for most of our winter is finally forecasted to move westward.  This pattern change could finally allow for larger and wetter storms to hit our region.  Active weather looks to be in the forecast at least through the first week of March.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: -3 to 8 deg. F.
Max. temperature in the last 24 hours: 15 to 17 deg. F.
Average wind direction during the last 24 hours: NE shifting to W
Average wind speed during the last 24 hours: 5 to 25 mph
Maximum wind gust in the last 24 hours: 35 mph
New snowfall in the last 24 hours: Trace to 3 inches
Total snow depth: 32 to 53 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Tuesday Tuesday Night Wednesday
Weather: Sunny then becoming partly cloudy. Mostly cloudy. Slight chance of snow showers after midnight. Mostly cloudy. Chance of snow showers.
Temperatures: 18 to 26 deg. F. 6 to 11 deg. F. 19 to 29 deg. F.
Wind Direction:
Wind Speed: Light winds Light winds Light winds
Expected snowfall: 0 in. Trace in. Up to 1 in.
For 8000 ft. to 9000 ft.
Tuesday Tuesday Night Wednesday
Weather: Sunny then becoming partly cloudy. Mostly cloudy. Slight chance of snow showers after midnight. Mostly cloudy. Chance of snow showers.
Temperatures: 10 to 20 deg. F. 3 to 9 deg. F. 12 to 22 deg. F.
Wind Direction: W
Wind Speed: 10 to 15mph with gusts to 25mph in the morning becoming light. Light winds Light winds
Expected snowfall: 0 in. Trace in. Up to 1 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

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