THIS AVALANCHE ADVISORY EXPIRED ON February 13, 2016 @ 6:40 am
Avalanche Advisory published on February 12, 2016 @ 6:40 am
Issued by Andy Anderson - Tahoe National Forest

LOW avalanche danger exists this morning while the snowpack remains frozen. As the day warms up and last night's refreeze melts, pockets of MODERATE danger will quickly form slopes steeper than 35 degrees on E-SE-S-SW aspects due to the possibility of loose wet avalanches. Small human triggered roller balls, pinwheels, and point-releases should comprise most of the loose wet activity, but some loose wet avalanches could involve enough snow to cause problems for backcountry travelers. 

2. Moderate

?

Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

?

Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

?

Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Even though the temperatures should not climb quite as high today as the last few days, daytime warming and some sunshine should be enough to melt through last night's weak refreeze. This warming and melting will allow enough wet snow to form that loose wet snow avalanches will be possible again today. Since the snowpack has already been through 9 days of melt-freeze cycles, these loose wet problems have become smaller and more isolated. Small human triggered roller balls, pinwheels, and point releases should represent the majority of the loose wet avalanches today, but a few of them could still entrain enough snow to cause problems for backcountry travelers in isolated areas or extreme terrain especially in areas where the melt freeze snow still has not transitioned to corn snow. E-SE-S-SW aspects should hold the best potential for loose wet problems. Depending on the amount of cloud cover today, some wet snow could start to form on N-NE aspects as well. 

Stepping off your equipment and sinking into wet snow above your boots can indicate that enough wet snow exists on a slope for a loose wet avalanche problem. Small loose wet instabilities like roller balls and pinwheels can foreshadow larger loose wet snow issues as well. These clues or other signs of wet snow issues mean that it is time to find a more frozen slope or switch to a different afternoon activity.

recent observations

Yesterday observations from Red Lake Peak and Tallac showed minor wet snow instabilities in the form of small human triggered pinwheels and small natural loose wet point releases on E aspects after 11 am. On Red Lake Peak, SE aspects up to 9600 ft. had a few inches of soft corn snow above a supportable melt-freeze crust between 10:30 am and 12 pm. Observers on Andesite Ridge did not see any recent loose wet snow avalanches on the SSW faces of Castle Peak yesterday prior to noon. On the N-NE aspects in all 3 of these areas, a mix of snow surface conditions ranging from scoured icy crusts in exposed near and above treeline locations to patches of soft cold snow in sheltered locations to widespread thin breakable melt freeze crusts existed. Snowpit data and general observations on the northerly aspects did not reveal any signs of instability. 

Weather and CURRENT CONDITIONS
weather summary

Last night represented yet another night with temperatures well above freezing at most of the upper elevations. Many sensors between 8000 and 9000 ft reported 6 am temperatures in the upper 30's and low 40's. Even though some high clouds may continue to move through the area today, the high pressure ridge will allow the warmer than normal temperatures and dry weather to persist across the region. The forecast calls for daytime highs in the mid 40's to low 50's with light to moderate winds above 7000 ft. today and tomorrow. Expect this dry, warm, calm weather to continue until the high pressure ridge breaks down.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 33 to 43 deg. F.
Max. temperature in the last 24 hours: 46 to 54 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 15 to 20 mph
Maximum wind gust in the last 24 hours: 40 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 62 to 81 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy Partly cloudy Partly cloudy becoming sunny
Temperatures: 48 to 55 deg. F. 25 to 35 deg. F. 43 to 50 deg. F.
Wind Direction: Southwest Southwest West
Wind Speed: 10 to 15 mph with gusts to 25 mph 10 to 15 mph with gusts to 25 mph 10 to 15 mph with gusts to 25 mph in the morning
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy Partly cloudy Partly cloudy becoming sunny
Temperatures: 44 to 51 deg. F. 30 to 36 deg. F. 39 to 46 deg. F.
Wind Direction: Southwest Southwest West
Wind Speed: 15 to 20 mph with gusts to 30 mph 15 to 20 mph with gusts to 35 mph 15 to 20 mph with gusts to 35 mph decreasing to 25 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.