THIS AVALANCHE ADVISORY EXPIRED ON February 17, 2016 @ 6:33 am
Avalanche Advisory published on February 16, 2016 @ 6:33 am
Issued by Steve Reynaud - Tahoe National Forest

Avalanche danger for today is Low on all aspects and elevations.  In the afternoon hours, isolated human triggered loose wet avalanches could become possible on E-SE-S-SW aspects on slopes steeper than 37 degrees.  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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  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Overnight temperatures were in the mid 30's to mid 40's above 8000'.  Winds have shifted from the NE-E direction to the SW and are forecasted to be in the moderate range for today.  Clear skies overnight have allowed for radiational cooling to provide a decent snow surface refreeze where air temperatures were above freezing.  Snow surface melt is expected to occur faster than yesterday due to warmer overnight temperatures and the shift to the warmer SW wind direction.  

Snow surface conditions are expected to be supportive through most of the morning hours.  By midday or early afternoon, human triggered loose wet avalanches could become possible in isolated areas on E-SE-S-SW aspects at all elevations.  These loose wet instabilities are expected to be human triggered and in the form of roller balls or pinwheels.

Planned timing of travel in avalanche terrain is critical to finding supportable snow conditions.  If boot penetration becomes 1' deep or greater, it is time to take active measures to avoid avalanches.   Change to a more northerly or westerly aspect and/or move to slopes less than 35 degrees in slope angle without steeper terrain above. 

recent observations

Recent observations from Castle Peak (Donner Summit area) and Silver Peak (Pole Creek area) showed a good overnight refreeze with supportable snow conditions throughout most of the day.  On SE-S aspects, 2'' of wet snow existed on top of a pencil hard 4'' melt freeze crust during the mid day hours providing good corn snow conditions.  On Silver Peak in rocky areas with low snow coverage, < 1' deep, snow supportability was borderline by midday. 

Observations from Silver Peak on north aspects did not show any problematic weak layers in the upper snowpack.  Several rain crusts were noted without any problematic associated near crust faceting.

Weather and CURRENT CONDITIONS
weather summary

High pressure will keep above average warm temperatures and sunny skies through today.  Ridgetop winds are forecasted to be from the SW in the moderate range.   Valley inversions continue to be in place with colder air lower in the valleys and warmer air aloft.  Overnight temperatures above 8000' are in the mid 30's to mid 40's which is warmer than the previous night.  A winter storm watch is in effect for Wednesday evening through Thursday morning as our next storm approaches our forecast area. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 39 to 44 deg. F.
Max. temperature in the last 24 hours: 49 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 15 to 20 mph
Maximum wind gust in the last 24 hours: 29 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 63 to 74 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Tuesday Tuesday Night Wednesday
Weather: Sunny Partly cloudy. Mostly cloudy then becoming partly cloudy. Slight chance of rain in the morning then rain and snow likely in the afternoon.
Temperatures: 52 to 59 deg. F. 31 to 37 deg. F. 40 to 47 deg. F.
Wind Direction: SW SW SW
Wind Speed: 10 to 15mph. Gusts up to 25mph in the afternoon. 15 to 25mph. Gusts up to 30mph increasing to 40mph after midnight. 40 to 50mph with gusts to 80mph.
Expected snowfall: 0 in. 0 in. Up to 1 in.
For 8000 ft. to 9000 ft.
Tuesday Tuesday Night Wednesday
Weather: Sunny Partly cloudy. Mostly cloudy then becoming cloudy. Slight chance of rain and snow in the morning then snow likely in the afternoon.
Temperatures: 47 to 54 deg. F. 28 to 35 deg. F. 36 to 43 deg. F.
Wind Direction: SW SW S
Wind Speed: 15 to 25mph with gusts to 35mph. 25 to 30mph with gusts to 45mph, increasing south 35 to 40mph with gusts to 60mph after midnight. 60 to 70mph with gusts to 105mph.
Expected snowfall: 0 in. 0 in. Up to 2 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.