THIS AVALANCHE ADVISORY EXPIRED ON February 16, 2016 @ 6:49 am
Avalanche Advisory published on February 15, 2016 @ 6:49 am
Issued by Brandon Schwartz - Tahoe National Forest

LOW avalanche danger continues for all elevations and aspects. Isolated human triggered loose wet avalanches may occur this afternoon on E-SE-S-SW aspects 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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  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Clear skies last night and overnight air temperatures in the low to mid 30s are expected to have allowed for a decent to very good snow surface refreeze to have occurred again last night. As is often the case in this area, radiational cooling is the major driving factor in creating snow surface refreeze in locations where overnight air temperatures were above freezing. With yesterdays surface melt not thawing all the way through the surface melt-freeze crust, a thick surface melt-freeze layer is expected this morning.

Supportable conditions are expected through the morning hours today. Snow surface melt will occur more rapidly today than yesterday, but ongoing light to moderate speed E to NE winds will aid in slowing the rate of snow surface melt. Sometime during the mid day to afternoon hours conditions will eventually become less supportable and loose wet snowpack instability will increase. Human triggered loose wet avalanche activity could occur this afternoon in isolated areas on E-SE-S-SW aspects.

Once several inches of wet snow form on the snow surface and body weight boot penetration approaches 1 foot deep or more into surface wet snow, 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. Planned timing of travel in avalanche terrain is critical for the preferred mix of frozen to melting, but still supportable snow surface conditions.

recent observations

Observations made and recieved yesterday from the Slide Mtn and Chickadee Ridge areas in Upper Ophir Creek (Mount Rose area) and from Negro Canyon (Donner Summit area) revealed a decent overnight snow surface refreeze on E-SE-S-SW aspects that remained supportable well into the afternoon hours. On the shaded N aspects of Chickadee Ridge, snow surface warming was reported around 8,800' indicating that thin surface melt-freeze crust formation is increasing in elevation on northerly aspects. No significant weak layers have been reported anywhere in the snowpack on NW-N-NE aspects over the past 7-10 days.

Weather and CURRENT CONDITIONS
weather summary

High pressure will keep above average air temperatures and sunny skies over the forecast area today and tomorrow. Ridgetop winds will remain light to moderate in speed out of the E today, shifting to the SW tomorrow. Air temperatures at 6 am this morning between 8,000' and 9,000' are in the low to mid 30s. This is a couple of degrees warmer than what was observed 24 hours ago. Maximum daytime air temperatures will be a few degrees warmer today and tomorrow than what occurred over the weekend. Significant changes are in store for Wed/Thurs as the next storm system impacts the forecast area. For the latest thinking on the upcoming storm, read the Area Forecast Discussion from NWS Reno.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 32 to 36 deg. F.
Max. temperature in the last 24 hours: 42 to 46 deg. F.
Average wind direction during the last 24 hours: NE
Average wind speed during the last 24 hours: 35 mph
Maximum wind gust in the last 24 hours: 56 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 61 to 75 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Sunny skies. Clear skies. Sunny skies.
Temperatures: 47 to 54 deg. F. 25 to 33 deg. F. 51 to 58 deg. F.
Wind Direction: E Variable SW
Wind Speed: 15 to 20 mph. Gusts up to 30 mph in the morning. Light winds Light winds, becoming 10 to 15 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Sunny skies. Clear skies. Sunny skies.
Temperatures: 44 to 51 deg. F. 25 to 32 deg. F. 47 to 54 deg. F.
Wind Direction: NE E shifting to S after midnight. SW
Wind Speed: 15 to 25 mph. Gusts up to 40 mph decreasing to 30 mph in the afternoon. 10 to 15 mph. 15 to 20 mph. Gusts up to 30 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.