THIS SNOWPACK SUMMARY EXPIRED ON February 20, 2019 @ 7:07 am
Snowpack Summary published on February 18, 2019 @ 7:07 am
Issued by Ryan Lewthwaite -

bottom line:

The mountain snowpack has Wind Slab deposits on aspects that face N-E which could pose a problem to travelers. On isolated terrain features these accumulations have formed Large Cornices, capable of releasing naturally or triggered by unsuspecting snowmobilers. The Storm Slab issue is settling out & a mostly right-side-up snowpack has taken shape, especially where rain infiltrated the snow last week. An upcoming Avalanche Awareness Class on March 15-16 needs participants, register below.

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.

The Wind Slabs have been growing for several days with SW & W winds. Lately the growth has subsided with the wind decrease & the focus has narrowed to the N-E aspects. Large areas of billowing deposits should have you making great terrain choices on low consequence slopes.

Avalanche Character 2: Cornice
Cornice Fall avalanches are caused by a release of overhanging, wind drifted snow. Cornices form on lee and cross-loaded ridges, sub-ridges, and sharp convexities. They are easiest to trigger during periods of rapid growth from wind drifting, rapid warming, or during rain-on-snow events. Cornices may break farther back onto flatter areas than expected.

Sharp & dramatic wind features including Large Cornices can be observed in all elevations & on aspects which contrast the SW flow. Around our travel corridor these deposits have been the majority of small avalanche activity. Unpredictable in nature these touchy snow forms could fall onto Slabs that could propagate a failure across slope.

Snowpack Discussion

The Storm Slab is settling into a nice right-side-up surface layer. This snow resides above a -P(pencil) hard MFcr(melt-freeze crust) which is acting as a barrier to the moist MFcl(melt-freeze clusters). Water is using capillary action to profuse through the lower snowpack making a solid substructure. The interface between the MFc & newer Storm Slab shows a lemon jump in hardness but bonding is in fine form, lessening concern here. Near & above treeline expect supportably firm windpack surfaces.

recent observations

~BWRA has a snowpack which is right-side-up with moist grains below a melt-freeze crust. NE wind loaded features, Slabs & Cornices are still suspect to triggering,

~Twin Lakes is showing a well bonded Storm Slab. Areas of firm windpack near & above treeline is mega-supportable.

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 9 deg. F.
Max. temperature in the last 24 hours: 20 deg. F.
Average wind direction during the last 24 hours: West
Average wind speed during the last 24 hours: Light mph
Maximum wind gust in the last 24 hours: Moderate mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 103 inches
weather

Snow showers will diminish today with light accumulations. Cold & dry air will be around today until tomorrows slider storm moves in with a few inches of snow. Winds will be light to moderate from the North. Sun is expected to show itself tomorrow.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Monday Monday Night Tuesday
Weather: Mostly cloudy with snow showers. Snow Level Below 7000' Partly cloudy then becoming clear. Snow Level Below 7000' Sunny. Snow Level Below 7000'
Temperatures: 11 to 19 deg. F. -2 to 4 deg. F. 21 to 27 deg. F.
Wind direction: North North North
Wind speed: 15 mph; gusts to 35 mph 15 mph; gusts to 35 mph 15 mph; gusts to 35 mph
Expected snowfall: 1 in. 0 in. 0 in.
For above 10000 ft.
  Monday Monday Night Tuesday
Weather: Mostly cloudy with isolated snow showers. Snow Level Below 7000' Partly cloudy then becoming clear. Snow Level Below 7000' Sunny. Snow Level Below 7000'
Temperatures: 3 to 8 deg. F. -5 to 0 deg. F. 14 to 19 deg. F.
Wind direction: North North North
Wind speed: 15 to 30 mph; gusts to 45 mph 15 to 30 mph; gusts to 50 mph 20 to 30 mph; gusts to 50 mph
Expected snowfall: 1 in. 0 in. 0 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.