Avalanche Forecast published on February 21, 2019 @ 6:59 am
This Avalanche Forecast expires in 1 hours, 15 minutes
This Forecast is valid for 24 hours
Issued by Andy Anderson - Tahoe National Forest - Sierra Avalanche Center

In near and above treeline terrain, the avalanche danger is MODERATE today due to the potential for wind slabs in some terrain. Below treeline the avalanche danger is LOW.

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.

1. Low

?

Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    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

SW and NE winds combined with snow available for transport and some new snow could have allowed new wind slabs to form on any aspect in near and above treeline terrain. Most of these wind slabs should remain relatively small and confined to areas near exposed ridgelines. They could still have consequences especially in complex or extreme terrain or in areas where terrain traps can magnify the consequences of an avalanche. Some larger wind slabs are not impossible on isolated terrain features with the most wind-loading. Continued NE winds today may help add size to some of these wind slabs.

Blowing snow, cornices, wind drifts, and other wind-created surface textures can all provide clues as to where a wind slab could exist. Light, cold, soft snow will exist in most sheltered areas and could provide great recreation with fewer chances for wind slabs or variable wind-affected surfaces.

recent observations

* Observations yesterday from exposed slopes near ridgelines on Silver Peak found signs of wind transport from both SW and NE winds. Some scoured areas held exposed rain crusts covered by a dusting of new snow. Large cornices still loomed over some wind-loaded slopes in this area and near Polaris Point. No current signs of unstable wind slabs were observed. 

* In sheltered terrain on northerly aspects, observations revealed no signs of instability in the Polaris Point area or the Silver Peak area. In both places, cold soft snow still existed on the surface with more dense snow below it. Some thin sun crusts existed on lower elevation SE and S aspects in the Silver Peak area. 

 

Weather and CURRENT CONDITIONS
weather summary

Periodic snow showers with bursts of graupel and high-intensity snowfall as well as moderate winds that varied from SW to NE have occurred over the last 24 hours. Light snow showers should continue today with up to 3 more inches of snow expected in most places. Areas S and SW of Lake Tahoe could see more snow due to some potential for lake effect snow. This storm should wind down tonight leaving calm cold weather in its wake. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 7 to 13 deg. F.
Max. temperature in the last 24 hours: 19 to 24 deg. F.
Average wind direction during the last 24 hours: SW shifting to NE overnight
Average wind speed during the last 24 hours: 20 to 30 mph
Maximum wind gust in the last 24 hours: 45 mph
New snowfall in the last 24 hours: 3 to 6 inches
Total snow depth: 105 to 144 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Mostly cloudy. Scattered snow showers. Snow levels below 7000 feet. Chance of precipitation is 40%. Mostly cloudy. Scattered snow showers. Snow levels below 7000 feet. Chance of precipitation is 35%. Partly cloudy then becoming sunny. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 20 to 25 deg. F. 3 to 9 deg. F. 25 to 30 deg. F.
Mid Slope Winds: Northeast around 15 mph with gusts to 30 mph. Northeast around 15 mph with gusts to 35 mph. East winds 10 mph in the morning then becoming light. Gusts up to 25 mph in the morning.
Expected snowfall: 90% probability of up to 3 inches. 10% probability of 3 to 5 inches. | SWE = up to 0.15 inch. Up to 1 inch. | SWE = less than 0.10 inch. No accumulation. | SWE = none.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Mostly cloudy. Scattered snow showers. Snow levels below 7000 feet. Chance of precipitation is 45%. Mostly cloudy. Scattered snow showers. Snow levels below 7000 feet. Chance of precipitation is 35%. Partly cloudy then becoming sunny. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 12 to 18 deg. F. 0 to 6 deg. F. 17 to 23 deg. F.
Ridge Top Winds: Northeast 15 to 25 mph. Gusts up to 35 mph increasing to 45 mph in the afternoon. Northeast 15 to 25 mph. Gusts up to 50 mph decreasing to 40 mph after midnight. East around 15 mph. Gusts up to 30 mph in the morning.
Expected snowfall: 90% probability of up to 3 inches. 10% probability of 3 to 5 inches. | SWE = up to 0.15 inch. Up to 1 inch. | SWE = less than 0.10 inch. 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

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