Avalanche Advisory published on February 24, 2018 @ 6:52 am
This Avalanche Advisory expires in 15 hours, 22 minutes
This advisory is valid for 24 hours
Issued by Brandon Schwartz - Tahoe National Forest

MODERATE avalanche danger lingers near and above treeline. LOW avalanche danger exists below treeline. Blowing snow is expected today with the possibility of a wind slab avalanche problem. Air temperatures warming to near freezing today will allow for a very slight possibility of a loose wet avalanche problem.

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

Increasing SW to W winds today will create areas of blowing snow in near treeline and above treeline terrain. Redistribution of snow on the ground will allow for the possibility of new wind slab formation. New wind slabs may be difficult to trigger today (stubborn or possibly unreactive).  New wind slabs will likely be small with a potential avalanche size of D1 expected (not large enough to bury a person). Consequences would come from being pushed into rocks or trees, over a cliff, or into a terrain trap.

Identify and avoid areas of potentially unstable wind slab by looking for newly wind drifted snow. Slopes that have cornice features or wind pillows across the upper portion of the slope are the most suspect. Areas of snow surface cracking in near treeline and above treeline terrain are an additional indication of unstable snow.

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

Loose wet is an unlikely avalanche problem today but cannot be ruled out if strong solar radiation occurs simultaneously with near freezing air temperatures during the mid day or afternoon hours. This will be fairly dependent on how rapidly and to what extent sun obscuring cloud cover develops today.

Look for natural or human triggered roller balls occurring in sun exposed, wind protected areas near treeline and below treeline on SE-S-SW aspects as the first sign of the potential for small (size D1) loose wet avalanches to occur.

recent observations

* Blowing snow with little in the way of problematic wind slab formation has been noted near and above treeline around the forecast area over the past two days. Winds have shifted back and forth between SW and NE.

* A few very small loose dry avalanches were observed yesterday on very steep slopes in the Ebbetts Pass area.

* Faceted snow either with or without an associated crust has been noted 1 to 1.5 feet below the snow surface in the Carson Pass and Ebbetts Pass areas. This layer warrants monitoring but has yet to become problematic due to the low density and lack of slab characteristics in the overlying snow.

Weather and CURRENT CONDITIONS
weather summary

A weather system will pass by to the NE of the forecast area today. The main impacts will be increasing winds and cloud cover this afternoon with the slight possibility of a few light snow showers over the forecast area. Ridgetop winds are expected to become strong out of the SW this afternoon. Upper elevation winds are forecast to shift to the N tonight and then back to the SW tomorrow. A gradual warming of maximum daytime air temperatures will continue today and tomorrow. The next possibility of meaningful snowfall across the forecast area occurs on Monday.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 13 to 21 deg. F.
Max. temperature in the last 24 hours: 17 to 23 deg. F.
Average wind direction during the last 24 hours: NE shifting to SW
Average wind speed during the last 24 hours: NE 23 mph | SW 30 mph
Maximum wind gust in the last 24 hours: NE 41 mph | SW 51 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 33 to 58 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Today Tonight Sunday
Weather: Partly cloudy skies becoming mostly cloudy. A slight chance of snow showers in the afternoon. Mostly cloudy skies, becoming partly cloudy. A slight chance of snow showers in the evening. Sunny skies, becoming partly cloudy.
Temperatures: 27 to 32 deg. F. 12 to 17 deg. F. 33 to 38 deg. F.
Wind Direction: SW to W W SW
Wind Speed: 15 to 20 mph with gusts to 40 mph, increasing to 20 to 30 mph with gusts to 60 mph in the afternoon. 15 to 25 mph with gust to 50 mph in the evening, decreasing to 10 to 20 mph. 10 to 15 mph with gusts to 40 mph.
Expected snowfall: Up to 2 in. Up to 1 in. 0 in.
For 8000 ft. to 9000 ft.
Today Tonight Sunday
Weather: Partly cloudy skies becoming mostly cloudy. A slight chance of snow showers in the afternoon. Mostly cloudy skies, becoming partly cloudy. A slight chance of snow showers in the evening. Sunny skies, becoming partly cloudy.
Temperatures: 22 to 28 deg. F. 10 to 15 deg. F. 28 to 34 deg. F.
Wind Direction: SW to W W shifting to N SW to W
Wind Speed: 25 to 40 mph. Gusts to 70 mph increasing to 80 mph in the afternoon. 20 to 35 mph. Gusts to 60 mph increasing to 70 mph after midnight. 20 to 30 mph. Gusts to 60 mph decreasing to 50 mph in the afternoon.
Expected snowfall: Up to 2 in. Up to 1 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.

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