THIS AVALANCHE ADVISORY EXPIRED ON January 19, 2015 @ 6:46 am
Avalanche Advisory published on January 18, 2015 @ 6:46 am
Issued by Brandon Schwartz - Tahoe National Forest

Avalanche danger remains LOW for all elevations and aspects. Small isolated areas of shallow wet snow instability could occur today on slopes 37 degrees and steeper. 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: Loose Wet
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    Certain
    Very Likely
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After several warm days with minimal to no overnight refreeze, widespread areas of surface wet snow exist. Continued warming today will increase the depth of wet snow at the surface a bit further. Free water drainage from the snowpack is well established following a couple weeks of melt-freeze cycles. Due to the low January sun angle, cloud cover, and weak incoming long wave radiation this time of year, the rate of free water production at the snow surface will remain slow today. The slow rate of free water production and efficient drainage of the snowpack are expected to keep areas of wet snow instability small and isolated. Areas where rain falls on snow will have a greater chance for potential human triggered loose wet avalanche activity today. For the vast majority of areas, signs of wet snow instability are expected to remain limited to human triggered roller balls and pinwheels that could occur on any aspect.

recent observations

Observations made yesterday on Red Vista (Carson Pass area) revealed wet surface snow 1 to 6 inches deep on all aspects at 10 am. Water droplets on conifer tree needles in very wind sheltered locations indicated that light rain had fallen in the area sometime Friday/Friday night. The overall snowpack in this area was warm, moist, and contained no evidence of faceting. All layers were very well bonded to one another. Signs of surface wet snow instability were very limited at noon, with one skier triggered pinwheel observed on a N aspect at 8,500'. Otherwise, ski cuts on convex terrain features did not produce signs of instability. Snow cover in the area differs dramatically by aspect with minimal snow cover remaining on S aspects and mostly continuous snow cover on N aspects.

Weather and CURRENT CONDITIONS
weather summary

A cold front is expected to pass through the region late this afternoon. Ahead of that cold front, continued warm air temperatures, cloud cover, isolated precipitation, and strong southwest ridgetop winds are expected for most of today. The best chance for precipitation exists north of I-80, over the far northern portion of the forecast area. Less than 1 inch of new snow is expected with snow levels ranging from 6,000' to 8,000'. Remote sensors are reporting air temperatures this morning at 8,000' to 9,000' in the mid 30s to low 40s. Maximum daytime air temperatures are forecast to reach the low 40s to low 50s today for areas above 7,000'. Southwest ridgetop winds are increasing in speed this morning with gusts to 44 mph reported along the Sierra Crest and gusts to 78 mph in the Mount Rose area. For Monday, decreasing cloud cover, decreasing winds, and cooler air temperatures are expected.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 35 to 41 deg. F.
Max. temperature in the last 24 hours: 44 to 48 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 25 mph
Maximum wind gust in the last 24 hours: 44 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 22 to 33 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. Isolated areas of light rain and snow, mainly north of I-80. Snow level 6,000' to 8,000'. Mostly cloudy skies. Mostly cloudy skies, becoming partly cloudy.
Temperatures: 45 to 51 deg. F. 22 to 29 deg. F. 42 to 48 deg. F.
Wind Direction: SW SW SW
Wind Speed: 20 to 30 mph with gusts to 45 mph. 25 to 30 mph with gusts to 45 mph, decreasing to 10 to 15 mph with gusts to 25 mph after midnight. 10 to 15 mph with gusts to 25 mph in the morning, becoming light.
Expected snowfall: 0 to trace in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Mostly cloudy skies. Isolated areas of snow showers, mainly north of I-80. Mostly cloudy skies. Mostly cloudy skies, becoming partly cloudy.
Temperatures: 43 to 49 deg. F. 23 to 30 deg. F. 39 to 45 deg. F.
Wind Direction: SW SW SW
Wind Speed: 35 to 45 mph with gusts to 70 mph. 35 to 40 mph with gusts to 60 mph, decreasing to 20 to 25 mph with gusts to 40 mph after midnight. 20 to 25 mph with gusts to 40 mph, decreasing to 10 to 15 mph with gusts to 25 mph in the afternoon.
Expected snowfall: 0 to trace 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.