THIS SNOWPACK SUMMARY EXPIRED ON February 18, 2021 @ 10:00 am
Snowpack Summary published on February 16, 2021 @ 10:00 am
Issued by Sue Burak - Bridgeport Avalanche Center

bottom line:

A prolonged period of strong SW to WSW winds has created new wind slabs in exposed alpine and subalpine terrain in the BWRA. These areas include Leavitt Bowl, upper Sardine Canyon, and the open slopes around Sonora Pass.. Wind slabs will be sensitive to triggering. 

Avalanche Character 1: Wind Slab
Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.

Human-triggered wind slab avalanches are possible today. Look out for fresh, dense pillow-like shapes below north to E facing slopes. Wind slabs sometimes will have a different texture and there will be a cohesive feel to the snow. It will be possible to trigger a small avalanche today on north to east aspects. Cross loading is likely on ridges well below ridgetops. There may be wind slabs in normally wind protected areas such as open glades below treeline. 

Wind slabs are usually triggered where it's "steepest and deepest"

Avalanche Character 2: Persistent Slab
Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.

Weak snow at the base of the snowpack is well bured by 3 to 5 feet of snow. This layer has not been reactive in recent instability tests. However, we contiue to monitor this layer. 

Snowpack Discussion

The snowpack above treeline in the BWRA has gained 5 inches of water content and 20 inches of snow in the last 5 days. The additional loading occurred over 5 days and is not expected to reactive weak snow at the bottom. Wind slabs can be medium hard to hard surfaces. Sometimes wind slabs can be so hard that snowmobiles barely leave a track. 

Yesterday, strong SW winds moved snow onto the north and east facing slopes in Leavitt Bowl and other north to east facing slopes.  Wind slabs could be found in open areas and open glades- these areas are popular riding areas so be aware and watch for slabs breaking up when riding in open terrain.

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 22 deg. F.
Max. temperature in the last 24 hours: 32 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 50 mph
Maximum wind gust in the last 24 hours: 86 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 98 inches

Ridgetop winds will continue to quite strong with gusts approaching 60 to 80 mph. Temperatures will be cooler for the next few days with highs in the upper 20's for elevations above 9,000 ft. The next storm approaches the West Coast late Thursday with snow forecasted to begin by Friday. This storm will be cold and supported by the polar jet stream. 


Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Tuesday Tuesday Night Wednesday
Weather: Partly sunny mostly clear Sunny
Temperatures: 28 deg. F. 7 deg. F. 28 deg. F.
Wind direction: NW N N
Wind speed: 15, gusting to 25 10-20 25, gusting to 40 mph
Expected snowfall: 0 in. 0 in. 0 in.
For above 10000 ft.
  Tuesday Tuesday Night Wednesday
Weather: Mostly cloudy and blustery Mostly clear Mostly clear
Temperatures: 28 deg. F. 7 deg. F. 30 deg. F.
Wind direction: NW N N
Wind speed: 15-20, gusts to 30 15-25 gust to 35 30-35, gusts to 55
Expected snowfall: 0 in. 0 in. 0 in.

This snowpack summary applies only to backcountry areas in the Bridgeport Winter Recreation Area. Click here for a map of the area. This snowpack summary describes general avalanche conditions and local variations always occur. This snowpack summary expires in 48 hours unless otherwise noted. The information in this snowpack summary is provided by the USDA Forest Service who is solely responsible for its content.