Avalanche Advisory published on February 22, 2017 @ 6:48 am
This Avalanche Advisory expires in 19 hours, 47 minutes
This advisory is valid for 24 hours
Issued by Brandon Schwartz - Tahoe National Forest

3. Considerable

?

Above Treeline

3. Considerable

?

Near Treeline

2. Moderate

?

Below Treeline

Avalanche danger is CONSIDERABLE near treeline and above treeline. Avalanche danger is MODERATE below treeline. Wind slab and storm slab avalanche problems continue today. Backcountry travelers should not be surprised by human triggered avalanche activity at any elevation. Dangerous avalanche conditions exist in many areas. Cautious and conservative terrain decisions and route selection are warranted today. 9:50 am update to add Wet Loose avalanche problem.

 

  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Continued SW winds and another 6 to 12 inches of new snow last night will have further developed wind slabs in near treeline and above treeline terrain on NW-N-NE-E-SE-S aspects. These new wind slabs sit on top of recently unstable wind slabs that formed during this storm cycle. Avalanches that occur today could be large and destructive. Large potentially dangerous cornices exist in many ridgeline areas.

Use clues such as blowing snow, cornice formations, and wind pillows to help identify recently wind loaded slopes that may hold unstable wind slabs and should be avoided.

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

New snow from last night was deposited under the coldest air temperatures of this storm cycle. Weak layers within the new snow may remain reactive today and allow for storm slab avalanche activity near treeline and below treeline on all aspects. The vast majority of any storm slab avalanche activity today will be human triggered.

Look for areas of snow surface cracking, especially while breaking trail and making fresh tracks either uphill or down. Avoid steep suspect slopes, especially in areas where snow surface cracking exists.

Avalanche Problem 3: Loose Wet
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

9:50 am update - Cloud cover is significantly less than forecast. Loose wet avalanches are now possible on E-SE-S-SW-W aspects at all elevations. Avalanche size could range from small to large. Areas around rocks and trees will heat up quickly despite below freezing air temperatures. Avoid travel in areas where natural roll ball activity is occurring.
 

CURRENT CONDITIONS Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 12 to 17 deg. F.
Max. temperature in the last 24 hours: 22 to 28 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 55 mph
Maximum wind gust in the last 24 hours: 103 mph
New snowfall in the last 24 hours: 17 to 21 inches
Total snow depth: 155 to 190 inches
weather

The last wave of the departing storm system deposited another 6 to 14 inches of snow over the forecast area last night. Bands of convective snow showers linger this morning in the wake of the departing storm system. Off and on snow showers today could be high intensity for short periods of time. Additional new snow amounts around the forecast area today are expected to range from a trace to possibly 3 inches. Cold air has moved into the region behind the departing storm system with air temperatures in the teens this morning for most locations above 7,000'. Ridgetop winds out of the SW remain strong in speed this morning. Winds are forecast to gradually decrease to moderate in speed tonight. For tomorrow expect light snow showers and maximum daytime air temperatures in the 20s above 7,000'.

 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
  Today Tonight Thursday
Weather: Mostly cloudy skies. Snow showers decreasing as the day progresses. Mostly cloudy skies. Isolated snow showers through the night. Mostly cloudy skies. Scattered snow showers.
Temperatures: 23 to 28 deg. F. 6 to 12 deg. F. 22 to 27 deg. F.
Wind direction: W W W
Wind speed: 15 to 25 mph with gusts to 45 mph. 15 to 20 mph with gusts to 35 mph. Light winds. Gusts to 25 mph in the morning.
Expected snowfall: Trace to 3 in. Up to 1 in. Up to 1 in.
For 8000 ft. to 9000 ft.
  Today Tonight Thursday
Weather: Mostly cloudy skies. Snow showers decreasing as the day progresses. Mostly cloudy skies. Isolated snow showers through the night. Mostly cloudy skies. Scattered snow showers.
Temperatures: 19 to 24 deg. F. 4 to 10 deg. F. 20 to 26 deg. F.
Wind direction: W W W
Wind speed: 20 to 35 mph. Gusts to 75 mph decreasing to 60 mph in the afternoon. 20 to 30 mph with gusts to 60 mph, decreasing to 15 to 20 mph with gusts to 40 mph after midnight. 15 to 20 mph. Gusts to 45 mph decreasing to 30 mph in the afternoon.
Expected snowfall: Trace to 3 in. Up to 1 in. Up to 1 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.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258

Subscribe to Central Sierra Avalanche Advisory | Avalanche Forecast From the Sierra Avalanche Center