THIS AVALANCHE ADVISORY EXPIRED ON March 26, 2015 @ 6:59 am
Avalanche Advisory published on March 25, 2015 @ 6:59 am
Issued by Brandon Schwartz - Tahoe National Forest

Areas of MODERATE avalanche danger will form today on slopes 37 degrees and steeper in response to daytime warming. Widespread loose wet instability in the form of roller balls, pinwheels, and loose wet avalanches not large enough to bury or injure a person are expected. Areas of MODERATE danger will be most widespread NW-N-NE-E aspects where snow cover existed prior to the last storm and may form in very isolated areas on SE-S-SW-W aspects.

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
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

As daytime warming progresses, areas of loose wet instability will become widespread at all elevations today on slopes 37 degrees and steeper. Roller balls and pin wheels will be widespread today as snow falls off of rocks and trees. Loose wet avalanches not large enough to bury or injure a person are possible today. The vast majority of instability is expected to occur on NW-N-NE-E aspects today where significant snow cover existed prior to the most recent storm cycle. Due to the fact that most SE-S-SW-W aspect slopes were bare ground prior to the last storm cycle, loose wet avalanches will be very isolated on the most sun exposed aspects. Keep in mind that terrain traps such as gullies and cliffs below can greatly magnify the consequences of very small avalanches that would otherwise be too small to bury or injure a person. 

recent observations

Observations made yesterday on Mt. Judah (Donner Summit area) indicated that avalanche problems had transitioned from wind slabs to loose wet instability. Intentional human triggered cornice collapses, ski cuts, and snowpit tests revealed no evidence of ongoing wind slab instability. Wind slabs up to 1.5 feet deep in near and above treeline on NW-N-NE-E aspects that had failed secondary to natural cornice collapse in the area on Monday were no longer unstable. Widespread human triggered roller balls and pin wheels up to 8 inches in diameter were noted on NW-N-NE-E aspects. No signs of actual loose wet avalanches were observed.

Weather and CURRENT CONDITIONS
weather summary

Weak storm systems over the past two days brought 4 to 6 inches of snowfall to the mid and upper elevations of the forecast area on Monday and light snow showers yesterday. Cloud cover has now cleared the region. A significant warming trend is expected to occur through Friday. Partly cloudy to sunny skies are forecast for today. Ridgetop winds are out of the east this morning and are moderate in speed. Wind speed is expected to decrease as the day progresses. Remote sensors are reporting air temperatures this morning in the mid 20s to low 30s between 7,000' and 9,600'. Air temperature inversion conditions are minimal. Maximum daytime air temperatures are forecast to reach the mid 40s to low 50s today for areas above 7,000'. Sunny skies, light winds, and an additional 10 degrees of daytime warming are forecast for tomorrow.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 28 to 31 deg. F.
Max. temperature in the last 24 hours: 35 to 40 deg. F.
Average wind direction during the last 24 hours: Southwest shifting to east
Average wind speed during the last 24 hours: 24 mph
Maximum wind gust in the last 24 hours: 44 mph
New snowfall in the last 24 hours: 0 to trace inches
Total snow depth: 17 to 40 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Wednesday Wednesday Night Thursday
Weather: Partly cloudy to sunny skies. Clear skies. Sunny skies.
Temperatures: 44 to 51 deg. F. 26 to 33 deg. F. 54 to 61 deg. F.
Wind Direction: E E Variable
Wind Speed: 20 to 25 mph with gusts to 35 mph in the morning, becoming light. Light winds Light winds
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Wednesday Wednesday Night Thursday
Weather: Partly cloudy to sunny skies. Clear skies. Sunny skies.
Temperatures: 43 to 49 deg. F. 26 to 33 deg. F. 53 to 59 deg. F.
Wind Direction: E E Variable
Wind Speed: 20 to 25 mph with gusts to 35 mph, decreasing to 10 to 15 mph in the afternoon. 10 to 15 mph in the evening, becoming light. 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.