THIS AVALANCHE ADVISORY EXPIRED ON April 10, 2017 @ 6:49 am
Avalanche Advisory published on April 9, 2017 @ 6:49 am
Issued by Steve Reynaud - Tahoe National Forest

Considerable avalanche danger will exist at all elevations due to loose wet, wind slab, and wet slab avalanche problems.  Full sun with Intense solar radiation and rapid warming will deteriorate the bonds within our recent storm snow.  Widespread avalanches could occur with natural and human triggered avalanches likely.

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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Loose wet avalanches will be very likely on E-SE-S-SW-W aspects at all elevations.  Full sun with intense solar radiation will deteriorate the bonds within our recent storm snow.  Widespread loose wet avalanches are expected to occur throughout the day as rapid warming occurs from direct April sunshine.  These loose wet avalanches could be both natural and human triggered and be large enough to injure or bury a backcountry user. 

Once a slope receives intense solar radiation, avalanche conditions along with travel conditions will deteriorate quickly.  Terrain traps, such as gullies, could magnify the consequences of even a small loose wet avalanche.  Managing aspects today will be key to finding the best snow and avoiding loose wet avalanches.

Avalanche Problem 2: Wind Slab
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Large wind slabs have formed from the strong to gale force SW winds with our recent storm snow.  Some lingering wind slabs may still exist in steep wind loaded terrain on NW-N-NE-E-SE aspects in near treeline and above treeline terrain.  As the sun comes out today, existing wind slabs may be further weakened by intense solar radiation especially wind slabs that are receiving direct sun on E-SE aspects.

Avoid steep wind loaded terrain and runout zones below large cornices.

Avalanche Problem 3: Wet Slab
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In isolated areas, wet slabs could be possible on E-SE-S-SW-W aspects at all elevations.  1 to 2.5' of recent storm snow is sitting on top of a firm rain crust.  As intense solar radiation and rapid warming occurs, the bonds that have formed within the recent storm snow will deteriorate.  Gully features and rock lined terrain may receive more radiation than open slopes.  When the snow surface becomes wet, it is time to leave the area or move to an aspect with colder snow.  Any wet slab avalanche activity could have large consequences.

recent observations

Observations were made and received from Jakes Peak (West Shore area), Trimmer Peak (Luther Pass area), Tamarack Peak (Mt. Rose area), and Poulsen Peak (Pole Creek area).  1.5 to 2.5' of recent settled storm snow existed throughout the forecast area above a rain crust from the beginning of the storm on Thursday.  Little to no storm slab and wind slab weakness was reported area wide.  Density changes were observed within the storm snow but no weakness was seen around these layers.  Minor wind loading continued to occur yesterday with additional snow accumulation up to 4 to 6''.

Weather and CURRENT CONDITIONS
weather summary

Light snow showers fell yesterday over part of the forecast area with up to another 4 to 6'' of accumulation.  Total storm snowfall over the last 3 days was up to 30''.  Drier conditions for today with mostly sunny skies and light winds after a cold start this morning.  A slight chance of light precipitation north of I-80 for Sunday night into Monday with unsettled weather into the mid week.  On Wednesday through Friday, anther moderate storm will impact our area with mountain snow and wind.   

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 11 to 18 deg. F.
Max. temperature in the last 24 hours: 30 deg. F.
Average wind direction during the last 24 hours: SW to NE to S
Average wind speed during the last 24 hours: 10 to 15 mph
Maximum wind gust in the last 24 hours: 43 mph
New snowfall in the last 24 hours: 4 to 6 inches
Total snow depth: 134 to 195 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Sunday Sunday Night Monday
Weather: Mostly sunny. Partly cloudy. Mostly cloudy. Slight chance of snow showers in the morning.
Temperatures: 33 to 38 deg. F. 21 to 27 deg. F. 37 to 43 deg. F.
Wind Direction: SW
Wind Speed: Light winds. Light winds becoming 10 to 15mph after midnight. Gusts up to 35mph. Light winds.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Mostly sunny. Partly cloudy. Mostly cloudy.
Temperatures: 29 to 35 deg. F. 20 to 26 deg. F. 33 to 39 deg. F.
Wind Direction: S SW SW
Wind Speed: 10 to 15mph with gusts to 35mph. 15 to 25mph with gusts to 50mph. 15 to 25mph. Gusts up to 50mph decreasing to 40mph 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.

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