THIS AVALANCHE ADVISORY EXPIRED ON April 11, 2014 @ 6:49 am
Avalanche Advisory published on April 10, 2014 @ 6:49 am
Issued by Brandon Schwartz - Tahoe National Forest

Early this morning, avalanche danger is LOW for all elevations and aspects. Avalanche danger will quickly increase to MODERATE danger by the late morning hours for all elevations and aspects in response to daytime warming. Small human triggered loose wet avalanches are expected today. Natural avalanche activity is unlikely but not impossible.

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: Loose Wet
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    Certain
    Very Likely
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    Possible
    Unlikely
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    Very Large
    Large
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Overnight minimum air temperatures were well above freezing once again last night and skies were partly cloudy. Snow surface refreeze is expected to be fairly superficial again this morning, having been dependent entirely on weak radiational cooling. A few hours of supportable snow surface conditions are expected early this morning. Once the surface melt-freeze crust is no longer supportable, avalanche danger will rapidly increase. When dealing with wet snow instability, the transition from stable to unstable snow can occur in as little as 15 minutes. By late morning, daytime warming is expected to have caused sufficient snow surface melting to allow for human triggered loose wet avalanches to occur on all aspects.

recent observations

Observations made yesterday on Tamarack Peak (Mount Rose backcountry) revealed that a poor overnight refreeze had occurred. The surface melt-freeze crust that had formed overnight was just 1.5 inches thick. Departing from the trailhead at 9:45am, 0.5 inch of wet snow existed on the snow surface in sun exposed areas at 8,650'. Conditions at that time were still skier supportable. At 10:40am wet snow boot penetration of 1 foot existed near the summit on an E aspect at 9,760'. Upon descending this E aspect at 11am, skier triggered roller balls 6 to 12 inches in diameter were triggered off of turns with conditions marginally skier supportable and degrading rapidly.

Weather and CURRENT CONDITIONS
weather summary

Sunny skies in the morning, increasing mid level cloud cover in the afternoon, well above freezing air temperatures, and decreased southwest ridgetop winds are forecast for today. Once again air temperatures between 6,500' and 9,600' remained above freezing last night with overnight minimum air temperatures in the upper 30s to low 40s. Maximum daytime air temperatures are forecast to reach the low 50s to low 60s today for areas between 7,000' and 9,000'. Light southwest ridgetop winds for today are expected to continue through tomorrow. A weather system forecast to pass near the coast of California will bring a small amount of moisture to the forecast area Friday and Saturday, just enough to create a slight chance of afternoon thunderstorms.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 37 to 42 deg. F.
Max. temperature in the last 24 hours: 49 to 54 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 26 mph
Maximum wind gust in the last 24 hours: 37 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 38 to 62 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Sunny skies becoming partly cloudy. Partly cloudy skies. Partly cloudy skies becoming mostly cloudy. A slight chance of thunderstorms in the afternoon.
Temperatures: 55 to 62 deg. F. 27 to 34 deg. F. 53 to 60 deg. F.
Wind Direction: Southwest Southwest Southwest
Wind Speed: Light winds Light winds Light winds
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Sunny skies becoming partly cloudy. Partly cloudy skies. Partly cloudy skies becoming mostly cloudy. A slight chance of thunderstorms in the afternoon.
Temperatures: 51 to 57 deg. F. 27 to 34 deg. F. 50 to 56 deg. F.
Wind Direction: Southwest Southwest Southwest
Wind Speed: 10 to 15 mph. 10 to 15 mph 10 to 15 mph
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.