THIS SNOWPACK SUMMARY EXPIRED ON February 5, 2019 @ 7:17 am
Snowpack Summary published on February 3, 2019 @ 7:17 am
Issued by Ryan Lewthwaite -

bottom line:

The strong winter storm we are experiencing has elevated the Avalanche Hazard to HIGH. Widespread avalanche activity is likely on all aspects & at all elevation bands. The potential is there for historically large & destructive avalanches with the prolonged duration & heavy rates of snowfall associated with this storm. The BWRA is under an AVALANCHE WATCH through Tuesday.

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.

Increased winds today, which shall reach Gale force by the afternoon, is actively transporting snow. The predominately Southwest winds are loading aspects facing NW-N-E-SE creating large slab deposits. These deposits could shed themselves naturally or if triggered by a traveler could be huge.  

Avalanche Character 2: Storm Slab
Storm Slab avalanches release naturally during snow storms and can be triggered for a few days after a storm. They often release at or below the trigger point. They exist throughout the terrain. Avoid them by waiting for the storm snow to stabilize.

The cohesive nature of the new snow could create widespread avalanche activity on all aspects. Forecasts are leaning towards a storm total over 5 feet in some higher alpine areas by Tuesday.

Snowpack Discussion

The growing load of new snow that is being rapidly dropped upon the landscape is worrisome. Natural avalanches on all aspects are likely today through Tuesday. Accumulation amounts & transport from SW winds will create tender storm & wind slabs. These slabs could be highly reactive to triggering from mountain travelers. The size & destructive potential of avalanches may be of historic proportions.

recent observations

-In the Twin Lakes zone a report of intact surface hoar was observed on isolated wind & sun protected terrain.

-The snowfall rates in BWRA were S5 or +2" per hour. 16" of new snow at the trailhead stormboard was collected by end of day. A mix of precipitation particles was seen including: Stellars, Rime, Broken PP, & Needles. Winds were light from the SW. Trees which had collected snow & rain overnight were dropping snow bombs on our avalanche awareness class & creating Loose Dry avalanches along the road corridor.

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 26 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: Moderate mph
Maximum wind gust in the last 24 hours: Gale mph
New snowfall in the last 24 hours: +28 inches
Total snow depth: 80 inches
weather

Heavy snow fall rates & damaging winds are likely today. In the alpine forecasted snow totals could reach 2 feet by the end of the day. Strong to Gale force winds from the Southwest will scour & transport snow creating large wind slabs & whiteout conditions.  Cold temperatures will continue to drop & we may see the coldest yet for the season. Hard rain fell below 8000' with the arrival of the system & low elevations may see a fresh rebuild of the snowpack. Snow levels will remain below 7000' through Tuesday morning.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Sunday Sunday Night Monday
Weather: Cloudy with snow. Snow Level Below 7000' Cloudy with snow. Snow Level Below 7000' Cloudy with snow. Snow Level Below 7000'
Temperatures: 26 to 34 deg. F. 19 to 24 deg. F. 22 to 30 deg. F.
Wind direction: Southwest Southwest South
Wind speed: 20 to 35 mph; gusts to 65 mph 15 to 30 mph; gusts to 65 mph 20 to 35 mph; gusts to 65 mph
Expected snowfall: 7 to 13 in. 11 to 20 in. 10 to 18 in.
For above 10000 ft.
  Sunday Sunday Night Monday
Weather: Cloudy with snow. Snow Level Below 7000' Cloudy with snow. Snow Level Below 7000' Cloudy with snow. Snow Level Below 7000'
Temperatures: 19 to 24 deg. F. 13 to 18 deg. F. 16 to 21 deg. F.
Wind direction: Southwest Southwest Southwest
Wind speed: 40 to 60 mph; gusts to 90 mph 30 to 45 mph; gusts to 70 mph increasing to 45 to 60 mph; gusts to 95 mph 40 to 60 mph; gusts to 90 mph
Expected snowfall: 8 to 13 in. 13 to 24 in. 12 to 24 in.
Disclaimer

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.