THIS AVALANCHE FORECAST EXPIRED ON March 28, 2020 @ 7:00 am
Avalanche Forecast published on March 27, 2020 @ 7:00 am
Issued by Steve Reynaud - Tahoe National Forest

Buried surface hoar beneath our recent storm snow has been found in the forecast region creating a persistent slab avalanche problem. Wind slab and loose wet avalanche problems will also be possible today.  Multiple persistent slab and wind slab avalanches were reported yesterday.  MODERATE avalanche danger will exist with human triggered avalanches expected.

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: Persistent Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Surface hoar that formed earlier this week has been buried by our recent storm snow.  This buried surface hoar now sits under around 1 foot of storm snow in wind protected areas and up to 2 to 3 feet deep in wind loaded areas.  The low density storm snow will continue to settle, gain strength and become more cohesive.  Multiple avalanches were reported yesterday with wide propagation, remote triggering, and whumpfing sounds on this buried surface hoar weak layer.  Continued human triggered avalanche activity is expected today.

This persistent slab problem exists on NW-N-NE aspects at all elevations.  The buried surface hoar will exist in open areas and not densely tree covered terrain.  Avalanches could continue to fail mid slope with very wide propagation.  Manage your aspects and slope angles carefully.  Remote triggering is very possible, so avoid connected terrain to larger avalanche paths. 

  

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

Wind slab avalanches continue to occur post storm.  Some of these wind slab avalanches could be failing on top of buried surface hoar or one of the many layers of graupel that was deposited during the storm.  Winds shifted briefly from the SW to the NE yesterday and remained light throughout the day.  They are forecasted to shift to the W today and increase to moderate to strong speed by this afternoon.  Additional wind transport of snow could start as winds increase.  Wind slab avalanches remain possible in near and above treeline areas.

Look for built out cornices, wind pillows, and steep wind loaded terrain.  These avalanches have been propagating wider than normal.  Avoid areas below large cornices and wind loaded slopes.  Manage terrain to reduce your risk.

  

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

Partly sunny skies today with intense March sunshine will create wet snow on solar aspects throughout the day.  Areas with more mid to high level cloud cover will have reduced loose wet activity.  Loose wet avalanches will become possible as the snow surface becomes wet and loses strength.  These loose wet avalanches could involve some or all of the recent storm snow. 

recent observations
Submit Observations

Multiple persistent slab avalanches failing on buried surface hoar were reported from the Blue Lakes area on Carson Pass.  Some of these avalanches had very wide propagation, were remotely triggered, and failed mid slope. 

Wind slab avalanches were reported from Silver Peak (Pole Creek area) and Frog Lake Cliff (Donner Summit area) yesterday.  4 other similar wind slab avalanches were observed near Silver Peak that were thought to have occurred on Wednesday.

Observations on Mt. Tallac at the site of a previous avalanche from Wednesday reveled buried surface hoar as the failure layer.  Whumpfing sounds were observed in the area along with snowpack tests that showed propagation likely on this weak layer.

Weather and CURRENT CONDITIONS
weather summary

Partly cloudy skies are expected today with a brief break in the unsettled weather  Mid to high level clouds will exist with some areas seeing full sun.  W winds are forecasted to increase in speed this afternoon to the moderate to strong range.  More unsettled weather returns on Saturday and Sunday with possible snow and wind. 

 

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 6 to 18 deg. F.
Max. temperature: 26 to 30 deg. F.
Average ridgetop wind direction: NE
Average ridgetop wind speed: 5 to 15 mph
Maximum ridgetop wind gust: 25 mph
New snowfall: Trace to 2 inches
Total snow depth: 66 to 88 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. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Chance of snow. Snow levels below 7000 feet. Chance of precipitation is 40%.
Temperatures: 32 to 37. deg. F. 15 to 21. deg. F. 33 to 39. deg. F.
Mid Slope Winds: Light winds. Gusts up to 25 mph in the afternoon. Light winds. Gusts up to 25 mph in the evening. Light winds.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. Up to 1 inch. | SWE = less than 0.10 inch.
For 8000 ft. to 9000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Chance of snow. Snow levels below 7000 feet. Chance of precipitation is 40%.
Temperatures: 26 to 32. deg. F. 12 to 18. deg. F. 27 to 33. deg. F.
Ridge Top Winds: West around 15 mph with gusts to 35 mph. Southwest around 15 mph with gusts to 30 mph in the evening becoming light. Southwest around 15 mph with gusts to 25 mph in the morning becoming light.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. Up to 1 inch. | SWE = less than 0.10 inch.
Disclaimer

This avalanche forecast is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This forecast 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 forecast applies only to backcountry areas outside established ski area boundaries. This forecast describes general avalanche conditions and local variations always occur. This forecast expires 24 hours after the posted time unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the avalanche forecast call (530) 587-3558 x258