THIS AVALANCHE FORECAST EXPIRED ON January 20, 2015 @ 6:53 am
Avalanche Forecast published on January 19, 2015 @ 6:53 am
Issued by Brandon Schwartz - Tahoe National Forest

Avalanche danger remains LOW for all elevations and aspects. Small isolated areas of wet snow instability will likely exist during the afternoon hours. 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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  • Likelihood ?
    Certain
    Very Likely
    Likely
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    Unlikely
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    Very Large
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A decent overnight snow surface refreeze is expected to have occurred last night with near to below freezing air temperatures and clearing skies during the last few hours of darkness to assist with radiational cooling. The best overnight snow surface refreeze will have occurred at the upper elevations (above 9,000') where air temperatures were below freezing for several hours last night. As the day progresses, areas of surface wet snow will develop, possibly on all aspects, especially at the low and mid elevations. Areas of wet snow instability that develop, mainly during the afternoon hours, are expected to remain small and isolated. As supportable melt-freeze crust transitions to unsupportable wet snow, small pockets of instability will become possible in steep terrain. Free water drainage from the snowpack has been well established over the past couple of weeks which is expected to keep large areas of instability from forming. Signs of instability are expected to remain limited to human triggered roller balls, pinwheels, and small human triggered loose wet sluffs.

recent observations

Observations were made and received yesterday from Chickadee Ridge (Mount Rose area), Castle Peak (Donner Summit area), and Red Lake Peak (Carson Pass area). A wide variance in overnight refreeze and the amount of wet snow that existed was observed during the morning hours. On Chickadee Ridge, overnight snow surface refreeze was better than expected with all aspects remaining frozen at 10 am. By 11 am supportable conditions remained with 1 to 2 inches of surface wet snow on SE and S aspects at 8,500' to 9,400'. On Castle Peak, a poor overnight snow surface refreeze had occurred with widespread areas of wet snow present at 9 am. By 10:30 am, marginally skier supportable conditions were reported on E-SE-S aspects between 7,200' and 7,900'.

On Red Lake Peak, a lack of snow made over snow travel difficult below 8,000'. Shaded northerly aspects between 8,400' and 9,000' held a less consolidated snowpack than what was observed in other Carson Pass area locations in recent days. Near crust facets were easily discernable in the upper portion of the snowpack, a significant contrast from the snowpack structure observed at similar elevation/aspect on Red Vista/Elephant's Hump the day prior. Moderate speed ridgetop winds kept large amounts of surface wet snow from forming on open slopes.

Weather and CURRENT CONDITIONS
weather summary

Building high pressure over the forecast area will lead to sunny skies, decreasing westerly winds, and above freezing air temperatures. Some areas of lingering cloud cover are expected to clear the region with sunny skies developing across the forecast area as the morning progresses. Ridgetop winds remain out of the southwest to west this morning and have decreased to light to moderate in speed. These winds kept air temperature inversion to a minimum last night with the coldest air at the upper elevations. Remote sensors are reporting air temperatures at 8,000' to 9,000' in the low 30s this morning. Maximum daytime air temperatures are forecast to reach the low to upper 40s today for areas above 7,000'. Wind speeds are expected to further decrease this afternoon and this evening. A cooling trend is expected for Tuesday.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 31 to 34 deg. F.
Max. temperature in the last 24 hours: 41 to 48 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 22 mph
Maximum wind gust in the last 24 hours: 58 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 23 to 33 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 cloud skies, becoming sunny. Partly cloudy skies. Partly cloudy skies, becoming mostly cloudy.
Temperatures: 43 to 49 deg. F. 20 to 27 deg. F. 36 to 43 deg. F.
Winds: W Variable Variable
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Partly cloud skies, becoming sunny. Partly cloudy skies. Partly cloudy skies, becoming mostly cloudy.
Temperatures: 39 to 45 deg. F. 22 to 29 deg. F. 33 to 40 deg. F.
Winds: W N shifting to SE after midnight. S
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.