THIS AVALANCHE ADVISORY EXPIRED ON March 29, 2017 @ 6:51 am
Avalanche Advisory published on March 28, 2017 @ 6:51 am
Issued by Brandon Schwartz - Tahoe National Forest

Rapid warming affecting recent storm snow will create areas of CONSIDERABLE avalanche danger today. Loose wet and wind slab avalanche problems are expected. Areas that did not undergo significant warming yesterday such as higher elevations or areas that spent most of yesterday under cloud cover will be particularly prone to avalanche activity. Identify and avoid areas of concern. Timing of travel in or below avalanche terrain will be critical for avoiding avalanche involvement.

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Loose Wet
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Rapid warming conditions are expected to create areas of loose wet avalanche activity today on all aspects at all elevations. Most loose wet avalanches today will be human triggered, with natural avalanches possible in some areas. Avalanche size could range from small to large enough to bury a person.

Avoid travel on or below steep slopes that are experiencing snow surface warming. Avoid steep slopes where roller ball activity is occurring. Backcountry travelers choosing to travel on steep sun affected slopes during the late morning and afternoon hours should expect to trigger avalanches.

Avalanche Problem 2: Wind Slab
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Ridgetop winds shifted from W to E yesterday evening. Overnight winds have been strong enough to create areas of blowing and drifting snow. Ridgetop winds today are expected out of the NE to E with ongoing strong gusts. Redistribution of recent storm snow is expected to have occurred in near treeline and above treeline areas. New wind slabs are expected on SE-S-SW-W-NW-N aspects. Some of these newly formed wind slabs could become increasingly unstable in response to rapid warming conditions. Avalanche size could range from small to large enough to bury a person.

Identify the areas of most recent wind drifted snow, wind loading, and wind slab formation. Avoid steep slopes were newly formed wind slabs are likely to exist. Keep in mind the potential for instability enhanced by rapid warming as well as the potential for sun effects on northerly aspects from the higher sun angles this time of year.

 

recent observations

Observations were made yesterday on Lincoln Ridge (Yuba Pass area) and on Tamarack Peak (Mount Rose area). On Lincoln Ridge, rapid warming conditions were apparent by the mid morning hours. SE aspect test slopes started to show signs of wet snow instability by late morning. Colder NE aspects showed no signs of wind slab instability in this area. In contrast, colder conditions existed all day in the Tamarack Peak area with evidence of wind slab instability and no signs of significant snow surface warming.

Weather and CURRENT CONDITIONS
weather summary

Short lived high pressure builds into the forecast area for today and tomorrow. The next weather system to bring precipitation to the region arrives on Thursday. For today expect sunny skies, above freezing air temperatures, and strong NE to E wind gusts over ridgetops. Further warming is forecast for Wednesday with gradually increasing cloud cover and light winds.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 20 to 25 deg. F.
Max. temperature in the last 24 hours: 31 to 38 deg. F.
Average wind direction during the last 24 hours: W shifting to E
Average wind speed during the last 24 hours: W 20 mph | E 37 mph
Maximum wind gust in the last 24 hours: W 43 mph | E 60 mph
New snowfall in the last 24 hours: 0 to 1 inches
Total snow depth: 123 to 177 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 skies. Clear skies. Partly cloudy skies, becoming mostly cloudy.
Temperatures: 44 to 49 deg. F. 25 to 31 deg. F. 52 to 57 deg. F.
Wind Direction: NE to E NE to E Variable
Wind Speed: Light winds. Gusts up to 35 mph decreasing to 25 mph in the afternoon. Light winds Light winds
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Tuesday Tuesday Night Wednesday
Weather: Sunny skies. Clear skies. Partly cloudy skies, becoming mostly cloudy.
Temperatures: 40 to 46 deg. F. 26 to 31 deg. F. 48 to 54 deg. F.
Wind Direction: NE to E NE to E Variable
Wind Speed: 15 to 25 mph. Gusts to 65 mph decreasing to 45 mph in the afternoon. 10 to 15 mph with gusts to 35 mph. Light winds
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.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258