THIS AVALANCHE FORECAST EXPIRED ON December 10, 2019 @ 6:59 am
Avalanche Forecast published on December 9, 2019 @ 6:59 am
Issued by Steve Reynaud - Tahoe National Forest

MODERATE avalanche danger will exist today in near and above treeline areas due to lingering wind slabs.  MODERATE avalanche danger will also exist in below treeline areas due to possible storm slabs.  Uncertainty exists about storm slabs and the potential for buried surface hoar.

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

Lingering wind slabs from our recent storm could remain reactive today to human triggering.  Wet heavy snow along with gale force winds during this last storm built out large wind slabs and cornices on NW-N-NE-E-SE aspects in near and above treeline terrain.  These wind slabs could remain reactive today and be large in size.  Wind direction has shifted overnight to the N/NE.  While forecasted to remain light through tonight, elevated NE winds could form new wind slabs on S-SW-W aspects in above treeline areas if winds increase in speed.   

Look for signs of blowing snow, large cornices, snow surface scouring, and wind pillows.  Avoid areas under large cornices and wind loaded terrain. 

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

Buried surface hoar has been reported at multiple locations throughout the forecast region and exists in some places below the recent 12/6-12/8 storm snow.  This buried surface hoar layer has shown unstable snowpack test results and whumpfing sounds.  Uncertainty exists about how widespread and reactive this layer could be.  No known avalanches on this layer have been reported at this point.  This weak layer has been found in open areas in below treeline terrain above 8000'.  Avalanches associated with this layer would involve all the recent storm snow, 1 to 2 feet.  Whumpfing, cracking, or recent avalanche activity in similiar areas would be a sign that this layer is present and reactive.

recent observations
Submit Observations

* On Rubicon Peak (West Shore) and Incline Lake Peak (Mt. Rose area) surface hoar was found buried under the recent storm snow.  Unstable snowpack test results and whumpfing sounds were reported.

* Reactive cornices and wind slabs were reported from multiple locations.

* Rain soaked snow was reported up to around 8000' at multiple locations throughout the forecast area with colder softer snow on top.

 

Weather and CURRENT CONDITIONS
weather summary

Patchy fog and clouds this morning should burn off with sunny skies later today.  Colder overnight temperatures last night with lows generally in the mid 20's above 7000'.  Light N/NE winds are forecasted into Tuesday.  Increasing winds with the chance of light snow are possible for Tuesday night.

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 21 to 26 deg. F.
Max. temperature: 39 deg. F.
Average ridgetop wind direction: SW shifting to NE
Average ridgetop wind speed: 10 to 30 mph
Maximum ridgetop wind gust: 45 mph
New snowfall: Trace to 3 inches
Total snow depth: 49 to 61 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy then becoming sunny. Snow levels below 7000 feet. Chance of precipitation is 0%. Clear then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 36 to 41. deg. F. 18 to 24. deg. F. 38 to 43. deg. F.
Mid Slope Winds: Light winds. Light winds. Light winds becoming southwest around 15 mph with gusts to 25 mph in the afternoon.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. No accumulation. | SWE = none.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy then becoming sunny. Snow levels below 7000 feet. Chance of precipitation is 0%. Clear then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 33 to 38. deg. F. 17 to 22. deg. F. 36 to 41. deg. F.
Ridge Top Winds: North 10 to 15 mph. Northwest 10 to 15 mph. Southwest around 15 mph increasing to 20 to 30 mph with gusts to 50 mph in the afternoon.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. No accumulation. | SWE = none.
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