THIS SNOWPACK SUMMARY EXPIRED ON February 22, 2018 @ 10:24 am
Snowpack Summary published on February 20, 2018 @ 10:24 am
Issued by Ryan Lewthwaite -

bottom line:

BWRA CLOSED to Snowmobiling. We received around 1" (2.5cm) new snow at 8000' & as you climb to around 9000' we observed nearly 5-6" (12cm). The winds have stripped SW-W-NW aspects at & above treeline, & loaded it into features on leeward NE-E-SE aspects. Soft wind slabs & cornices have formed on these leeward slopes, elevating the avalanche hazard. There is also a potential for loose dry snow releases today as you travel by foot in the BWRA.

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.

Strong to moderate winds have displaced snow to NE-E-SE aspects creating soft wind slabs below treeline. Wind slabs were primarily less dense than could be expected & stubborn to propagate fractures. The very low density snow rests on a firm crust created by previous sun & wind. If you are able to trigger an avalanche it will slide on this stiff crust & could be nearly a foot deep in isolated areas. Look for the instability signs like: natural loose avalanches, a textureless slope, cornices, or billows & pillows.

Avalanche Character 2: Loose Dry
Loose Dry avalanches exist throughout the terrain, release at or below the trigger point, and can run in densely-treed areas. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells.

The cold dry powder conditions are great for backcountry skiing but pose a possible avalanche problem. Although relatively small in size a loose dry avalanche can sweep you off your feet & take you into terrain or flush you into trees you may have been avoiding.

Snowpack Discussion

Our snowpack is still thin & highly variable. New snow has not accumulated evenly due to strong & moderate winds. The new cold smoke that fell is easily transported by wind & has collected in soft wind slabs on leeward aspects. The stout crust this accumulation sits on will be a perfect bed-surface for any avalanche activity. Faceting is occurring below the crust & may prove to be a future problem layer.

recent observations

A new 6" (12cm) fell on the evening of the 18th & later into the day on the 19th. Below the new snow is a firm crust left behind from days of sun & wind. This will become the bed-surface for any new avalanche activity. Strong to moderate winds came from the SW-W-NW & were swirling for some time during observations.

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 3 deg. F.
Max. temperature in the last 24 hours: 19 deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours: mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: 6 inches
Total snow depth: 19 inches
weather

Much colder than it has been, reaching teens & single digits at night. Strong to moderate winds were prevailing from the SW-W-NW & became swirling at times. Blowing snow & precipitating snow has accumulated around 6" (12cm) below treeline on leeward slopes.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Tuesday Tuesday Night Wednesday
Weather: Sunny Mostly cloudy with a slight chance of snow showers late Mostly cloudy with a chance of snow showers later
Temperatures: 12 - 22 deg. F. 2 - 7 deg. F. 15 - 25 deg. F.
Wind direction: Light winds Light winds Light winds
Wind speed: Light winds Light winds Light winds
Expected snowfall: 0 in. trace in. 1 in.
For above 10000 ft.
  Tuesday Tuesday Night Wednesday
Weather: Sunny Mostly cloudy with a slight chance of snow showers late Mostly cloudy with a chance of snow showers
Temperatures: 7 - 17 deg. F. (-2) - 3 deg. F. 8 - 18 deg. F.
Wind direction: West Light winds Light winds
Wind speed: 10 to 15 mph, gusts to 25 mph then becoming light Light winds Light winds
Expected snowfall: 0 in. trace in. 1 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.