THIS AVALANCHE ADVISORY EXPIRED ON February 29, 2016 @ 6:53 am
Avalanche Advisory published on February 28, 2016 @ 6:53 am
Issued by Brandon Schwartz - Tahoe National Forest

Early this morning, LOW avalanche danger exists for all elevations and aspects. Areas of MODERATE avalanche danger are exected to form at all elevations on SE-S-SW aspects on slopes 35 degrees and steeper in response to daytime warming. Isolated areas of loose wet instability may occur on W-NW-N-NE-E aspects as well.

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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    Very Likely
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Despite the cloud cover, areas of loose wet instability are expected to form today mainly on SE-S-SW aspects as daytime warming progresses. Lesser amounts of snow surface melt and subsequent instability are expected on W-NW-N-NE-E aspects today. A few isolated areas have made the full transition to "corn snow" where surface wet snow will exist on top of thick melt-freeze crust during much of the day's melt cycle. However in the vast majority of areas, this full transition has yet to occur and surface wet snow will be found on top of drier remnant storm snow. In these more unstable areas, no significant crust exists at the base of the wet surface snow during the majority of the melt phase. This wet snow over drier remnant storm snow is prone to human triggered loose wet avalanche activity.

Use clues such as human triggered roller balls and pinwheels approaching or exceeding 1 foot in diameter and/or boot top depth penetration into wet snow to determine when critical amounts of surface wet snow exist. When these clues are observed, move to lower angle slopes of less than 30 degree slope angle without steeper terrain above or change to a less sun exposed and more frozen aspect.

recent observations

Observations made yesterday on the S-SE aspects of Mt. Judah (Donner Summit area) revealed deep wet snow and signs of loose wet instability below 8,000' by 11 am. Deep boot penetration into surface wet snow, skier triggered roller balls, and tiny skier triggered loose wet sluffs were observed in the area. Ridgetop winds were creating convective cooling that kept the snow surface frozen near ridgetop level while significant melt was rapidly occurring 100' to 200' below. Snow surface melt was significantly slower to occur on W and N aspects as is typically the case. Several creek beds at mid slope level were observed as open and flowing, indicating fairly well established free water drainage from the snowpack.

Weather and CURRENT CONDITIONS
weather summary

A weather system passing to the north of the forecast area today will spread mid to high level cloud cover over the region. Some occasional sun breaks are expected throughout the day today. The passing system will also keep moderate speed SW ridgetop winds ongoing. Winds are expected to decrease tonight and tomorrow. Remote sensors are reporting air temperatures this morning between 7,000' and 9,000' in the low to upper 30s. Maximum daytime air temperatures for areas above 7,000' are forecast to reach the mid 40s to low 50s today. For Monday expect decreasing cloud cover, lighter winds, and similar maximum daytime air temperatures.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 30 to 37 deg. F.
Max. temperature in the last 24 hours: 41 to 47 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 21 mph
Maximum wind gust in the last 24 hours: 42 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 55 to 85 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 cloudy skies. Mostly cloudy skies. Partly cloudy skies.
Temperatures: 46 to 53 deg. F. 21 to 28 deg. F. 47 to 54 deg. F.
Wind Direction: SW W Variable
Wind Speed: 10 to 15 mph with gusts to 25 mph. 10 to 15 mph with gusts to 25 mph in the evening, becoming light. Light winds
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Mostly cloudy skies. Mostly cloudy skies. Partly cloudy skies.
Temperatures: 45 to 51 deg. F. 21 to 28 deg. F. 45 to 51 deg. F.
Wind Direction: W W to NW W
Wind Speed: 15 to 25 mph with gusts to 40 mph. 25 to 30 mph with gusts to 40 mph, shifting and decreasing to 10 to 15 mph with gusts to 25 mph after midnight. 10 to 15 mph. Gusts up to 25 mph 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.