THIS AVALANCHE ADVISORY EXPIRED ON April 8, 2014 @ 7:00 am
Avalanche Advisory published on April 7, 2014 @ 7:00 am
Issued by Andy Anderson - Tahoe National Forest

On E-SE-S-SW-W aspects steeper than 35 degrees MODERATE avalanche danger will form as the day warms up. Some pockets of MODERATE avalanche danger may also form on NW-N-NE aspects that receive sunshine today.

Loose wet snow avalanches will be possible today. Larger wet slab avalanches remain unlikely, but isolated wet slab avalanches will not be impossible as the day warms up.

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 temperatures remained above freezing below 9000 ft. last night, clear skies should have allowed a marginal refreeze to occur.  Today's intense sunshine and very warm temperatures will quickly melt through this refreeze. More widespread loose wet snow instabilities like roller balls, pinwheels, and wet point release avalanches should become possible today. Most of these loose wet avalanches should remain too small to bury a person, but they could still push a person into an area with other consequences or could become more serious in areas where terrain traps exist. Loose wet avalanches will be most prevalent on the E-SE-S-SW-W aspects but could also occur on any slope that receives sun including the northerly aspects today.

Avalanche Problem 2: Wet Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Larger wet slab avalanches should still remain unlikely today. However, they are not impossible on the most sun exposed slopes. E-SE-S-SW-W aspects hold the best potential for this unlikely problem, but northerly aspects where sunshine and warm temperatures cause significant wet snow to form could also hold an unlikely but not impossible isolated wet slab. These kind of avalanches are very difficult to predict and confidence in whether or not they could occur today is low. This uncertainty means that wet slabs deserve thought and caution whenever there is a chance they could become a problem.

Surface wet snow instabilities like the pinwheels and roller balls mentioned above and simple observations such as sinking into wet snow above your boot tops indicate that enough wet snow exists for larger wet snow instabilities like wet slabs or larger wet loose avalanches to occur.  Seeing these things means it is time to find a colder slope or get off the snow and find another activity for the afternoon.

recent observations

Yesterday wet snow existed on almost all slopes in the Castle Peak area. Only the shaded northerly aspects above 8600 ft. still held patches of soft cold snow. Roller balls and small wet point releases occurred near exposed rocks on steep SW facing aspects, and ski cuts on steep SE-S facing test slopes triggered pinwheels and wet snow sluffs. Runnels in the snow surface on most aspects, increased water output, and water dripping from cornices all indicated significant warming and melting in the snowpack yesterday. Wet avalanche activity was reported on a NE facing near treeline slope in the Crater Lake area yesterday. This slide started with a depth of about 1 ft. and entrained more snow and got wider as it ran down slope.

Weather and CURRENT CONDITIONS
weather summary

The high pressure ridge over the region will keep the weather warm and sunny. Last night overnight lows did not drop below freezing. Today temperatures should climb into the mid to upper 50's above 7000 ft, and the forecast calls for them to climb a few degrees warmer tomorrow. Winds should remain light and variable today before shifting to the southwest tomorrow. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 33 to 38 deg. F.
Max. temperature in the last 24 hours: 42 to 49 deg. F.
Average wind direction during the last 24 hours: Northeast and east
Average wind speed during the last 24 hours: 10 to 20 mph
Maximum wind gust in the last 24 hours: 43 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 41 to 69 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 Clear Sunny
Temperatures: 52 to 59 deg. F. 30 to 37 deg. F. 54 to 61 deg. F.
Wind Direction: Variable Variable Southwest
Wind Speed: Light Light 10 to 15 mph with gusts to 25 mph in the afternoon
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Sunny Clear Sunny
Temperatures: 51 to 57 deg. F. 31 to 38 deg. F. 52 to 58 deg. F.
Wind Direction: Variable South Southwest
Wind Speed: Light 0 to 5 mph increasing to 10 to 15 mph after midnight 15 to 25 mph with gusts to 35 mph
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.