THIS AVALANCHE ADVISORY EXPIRED ON November 20, 2015 @ 6:51 am
Avalanche Advisory published on November 19, 2015 @ 6:51 am
Issued by Andy Anderson - Tahoe National Forest

The avalanche danger remains LOW on on all aspects and elevations. While avalanches have become unlikely, they are not impossible. Small avalanches can still occur in isolated areas or extreme terrain during LOW danger. Continue to use caution and watch for unstable snow on isolated terrain features when traveling in the backcountry.

It early season and numerous exposed or barely covered season-ending obstacles exist. While the avalanche danger has decreased, these hazards remain.

1. Low

?

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

1. Low

?

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

1. Low

?

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
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Even though the weather has remained relatively static over the last few days, the snowpack continues to change. Data and observations show that the most recent snow continues to settle and consolidate. It also indicates that the sugary snow layers (facets) in the bottom of the snowpack on the NW-N-NE aspects remain weak. While human-triggered avalanches involving this weak layer remain unlikely, it could become problematic during the next storm or sooner if the trend of consolidating snow in the upper half of the snowpack and weakening snow in the lower snowpack continues. In most areas the snowpack remains shallow enough that numerous exposed or barely covered rocks, stumps, logs, and other obstacles/anchors poke through this layer

A few small isolated wind slabs lurking in complex or extreme terrain or on unsupported slopes represent the other unlikely, isolated, and small but not impossible issue. These areas could include those tempting filled-in looking couliors or hanging snowfields with cliffs below them. Keep in mind that after the recent winds, if a near treeline or above treeline area looks nicely filled in, wind slabs likely exist in that area.

recent observations

Yesterday on Rubicon Peak, snowpit and hand pit data showed a layer of weak sugary snow (facets) near the bottom of the snowpack on the NW-N-NE aspects above 8000 ft. Tests targeting this layer indicated that if it breaks the resulting fracture could propagate along that weak layer. Observations in this area also showed numerous exposed and barely covered rocks, stumps, logs, trees, and other obstacles/anchors that poked through this layer and interrupted it. Overall snow depth ranged from 4-8 inches below 8000 ft. to 18-24 inches near 9000 ft. Above 8000-8200 ft. the snow surface on the northerly aspects remained soft and unconsolidated. Below that elevation a breakable melt-freeze crust existed on the snow surface. Traveling on skis in this area remains difficult to do without hitting the myriad of obstacles buried just below the surface.

Weather and CURRENT CONDITIONS
weather summary

Another temperature inversion has settled across the area with lower elevation sensors reporting temps in the 20's and low 30's while the upper elevations stations stayed mostly above freezing last night. The forecast calls for continued warm and dry weather due to the weak high pressure ridge over the region. Winds should shift to west and a few clouds may develop across the forecast area today and tonight as a weak low pressure moves past to the north.  As this front passes, the winds should shift back to the north and east and temperatures should cool off a few degrees tomorrow. Above 7000 ft. the forecast calls for daytime highs in the low to mid 40's tomorrow instead of the upper 40's and low 50's that the area may reach today.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 30 to 42 deg. F.
Max. temperature in the last 24 hours: 44 to 49 deg. F.
Average wind direction during the last 24 hours: North to Northeast
Average wind speed during the last 24 hours: 10 mph
Maximum wind gust in the last 24 hours: 24 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 10 to 20 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 becoming partly cloudy during the day Partly cloudy Partly cloudy
Temperatures: 43 to 50 deg. F. 29 to 35 deg. F. 39 to 46 deg. F.
Wind Direction: West West Variable
Wind Speed: 10 to 15 mph with gusts to 25 mph 10 to 15 mph with gusts to 25 mph Light
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Sunny becoming partly cloudy during the day Partly cloudy Partly cloudy
Temperatures: 40 to 47 deg. F. 26 to 33 deg. F. 39 to 46 deg. F.
Wind Direction: West West Northeast
Wind Speed: 15 to 25 mph with gusts to 40 mph 15 to 25 mph with gusts to 35 mph 10 to 15 mph with gusts to 25 mph in the morning
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.