THIS AVALANCHE ADVISORY EXPIRED ON March 14, 2015 @ 6:39 am
Avalanche Advisory published on March 13, 2015 @ 6:39 am
Issued by Brandon Schwartz - Tahoe National Forest

Avalanche danger remains LOW for all elevations and aspects. Small minor loose wet instabilites may form in response to daytime warming. Normal caution is advised.

1. Low

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Above Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Normal Caution
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  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

A strong snow surface refreeze is expected to have occurred last night. This is due to radiational cooling under mostly clear skies with air temperatures at to a few degrees above freezing. As daytime warming progresses, areas of wet surface snow will form in all but the most heavily shaded areas. The lack of snow cover remaining on the vast majority of SE-S-SW aspects will limit the amount of instability that forms today. Of the slopes with continuous snow cover, E and W aspects will experience the greatest amount of wet snow formation with lesser amounts on NW-N-NE aspects. Human triggered roller balls are the expected extent of wet snow instability today. Isolated human triggered loose wet avalanches could occur on slopes 37 degrees and steeper, but are expected to be very small and with little consequence if size and type are the only factors. Secondary terrain hazards such as cliffs and terrain traps below always hold the potential to greatly magnify consequences of an avalanche that would otherwise be too small to bury or injure a person.

recent observations

Observations made yesterday on Mt. Judah (Donner Summit area) revealed that wet snow was present on all aspects at mid day up to the summit at 8,200'. Recent new snow, now settled to around 0.5 inch in most areas was rapidly assimilating with the crust and wet snow in the top 6 inches of the snowpack. Minor skier triggered roller balls occurred while descending the E face of Mt. Judah at 12:30 pm. Conditions were marginally skier supportable at that time. Isolated, localized wet snow collapse was triggered three times while skinning through an open, low angle E aspect at 7,860' at 1 pm. Snowpack collapse was occurring within surface wet snow. Overall, evidence of wet snow instability was minor and localized at mid day.

Significant melt out has occurred on most SE-S-SW-W aspects in this area. On these aspects large areas of bare ground exist with a few sizable snow patches remaining in isolated locations. In general, continuous snow cover in the Donner Summit area is limited to NW-N-NE-E aspects. This is also the case in most other portions of the forecast area.

Weather and CURRENT CONDITIONS
weather summary

High pressure is firmly in place over the region. A warming trend is expected today and tomorrow with increasing mid and high level cloud cover over the forecast area. Remote sensors are reporting air temperatures this morning in the low to upper 30s between 8,000' and 9,600' with minimal inversion conditions. Maximum daytime air temperatures are forecast to reach the mid 40s to mid 50s today for areas above 7,000'. Ridgetop winds have gradually decreased in speed overnight and are light in speed out of the ESE this morning. Light winds out of the S to SE are expected for today. Moderate to strong SW ridgetop winds are forecast for tomorrow.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 31 to 39 deg. F.
Max. temperature in the last 24 hours: 42 to 47 deg. F.
Average wind direction during the last 24 hours: East
Average wind speed during the last 24 hours: 29 mph
Maximum wind gust in the last 24 hours: 62 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 27 to 45 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy skies. Mostly cloudy skies. Mostly cloudy skies.
Temperatures: 47 to 54 deg. F. 35 to 41 deg. F. 50 to 57 deg. F.
Wind Direction: S S SW
Wind Speed: Light winds 10 to 15 mph. Gusts up to 25 mph after midnight. 15 to 20 mph. Gusts to 25 mph increasing to 35 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy skies. Mostly cloudy skies. Mostly cloudy skies.
Temperatures: 46 to 52 deg. F. 35 to 41 deg. F. 49 to 55 deg. F.
Wind Direction: SE S SW
Wind Speed: 10 to 15 mph. 15 to 20 mph. Gusts up to 30 mph after midnight. 20 to 30 mph. Gusts up to 35 mph increasing to 50 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.