THIS AVALANCHE ADVISORY EXPIRED ON March 1, 2016 @ 6:51 am
Avalanche Advisory published on February 29, 2016 @ 6:51 am
Issued by Brandon Schwartz - Tahoe National Forest

Early this morning, avalanche danger is LOW for all elevations and aspects. Areas of MODERATE avalanche danger are expected to form in response to daytime warming at all elevations on E-SE-S-SW-W aspects on slopes 35 degrees and steeper due to the possibility of loose wet avalanches. Isolated areas of loose wet instability may form on NW-N-NE 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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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

A decent to strong snow surface refreeze is expected to have occurred last night with slightly colder overnight low air temperatures and decreased cloud cover as compared to 24 hours ago. That said, snow surface melt is expected to occur more rapidly today than yesterday due to decreased cloud cover, lighter winds, and slightly warmer maximum daytime air temperatures. Areas of unstable wet snow are expected to form by the late morning to mid day hours mainly on E-SE-S-SW-W aspects, especially below 8,000'. Instability will likely extend to the higher elevations as the afternoon progresses. Lesser amounts of snow surface melt are expected to occur on NW-N-NE aspects today. Subsequent loose wet instability will be less on NW-N-NE aspects, but may still occur in isolated areas.

Use clues such as human triggered roller balls and pinwheels approaching or exceeding 1 foot in diameter and/or boot penetration 10 to 12 inches deep or more into wet snow to determine when critical amounts of surface wet snow exist. When these clues are present, move to lower angle slopes of less than 30 degrees in slope angle without steeper terrain above or change to a less sun exposed and more frozen aspect.

recent observations

Observations made and received yesterday from Steven's Peak (Carson Pass area), Mt. Tallac (Desolation Wilderness area), and Castle Peak (Donner Summit area) all indicated that surface wet snow was slow to form yesterday above 8,500' to 9,000' due to the combination of cloud cover and moderate speed SW winds. Below 8,500', surface wet snow formation occurred relatively faster, but skier supportable conditions were reported on the SW aspects of Castle Peak during the late afternoon hours. Many SE-S-SW aspects and low to mid elevation E aspects have made the transition to "corn snow". Upper elevation E aspects and low to mid elevation NW-N-NE aspects remain transitional with a fairly thin layer of surface melt-freeze snow on top of drier older snow yet to under go melt-freeze. Upper elevation NW-N-NE aspects tend to hold fairly dense surface snow that has yet to undergo melt-freeze with the exception of low angle areas.

Weather and CURRENT CONDITIONS
weather summary

High pressure remains in place over the region. Varying periods of mid to high level cloud cover are expected today and tomorrow. Remote sensors are reporting air temperatures in the 7,000' to 9,000' range in the upper 20s to mid 30s at 6 am this morning. Maximum daytime air temperatures above 7,000' today are forecast to reach the mid 40s to mid 50s. Light to moderate speed ridgetop winds out of the W are expected today. A weather system passing to the north of the forecast area will increase SW ridgetop winds into the strong to gale force range tomorrow afternoon.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 27 to 36 deg. F.
Max. temperature in the last 24 hours: 42 to 46 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 17 mph
Maximum wind gust in the last 24 hours: 36 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.
Monday Monday Night Tuesday
Weather: Partly cloudy skies. Partly cloudy skies. Partly cloudy skies.
Temperatures: 49 to 55 deg. F. 28 to 34 deg. F. 51 to 59 deg. F.
Wind Direction: W SW SW
Wind Speed: Light winds 10 to 15 mph 15 to 20 mph with gusts to 30 mph, increasing to 25 to 30 mph with gusts to 40 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy skies. Partly cloudy skies. Partly cloudy skies.
Temperatures: 43 to 49 deg. F. 25 to 32 deg. F. 46 to 52 deg. F.
Wind Direction: W SW SW
Wind Speed: 15 to 20 mph with gusts to 30 mph. 15 to 25 mph with gusts to 35 mph. 30 to 35 mph with gusts to 50 mph, increasing to 45 to 50 mph with gusts to 80 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.