THIS SNOWPACK SUMMARY EXPIRED ON February 18, 2019 @ 7:27 am
Snowpack Summary published on February 16, 2019 @ 7:27 am
Issued by Ryan Lewthwaite -

bottom line:

There will be frequent Avalanche Activity today! Growing Wind & Storm Slabs will increase the Avalanche Danger to nearly historic potentials. Yesterday at the trailhead parking was very limited & accumulations around 25" kept us shoveling. Places where previous slopes showed limited hazard are now suspect to avalanching with ferrocity. When conjuring a travel plan today make certain you speak of the places that you should NOT travel & communicate constantly to keep a visual on your crew.

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.

A rumor of winds reaching over 170 mph with the recent storm were spoken of. Low density snow is easily transported to places where thick deposits already exist, creating potentially deep failures. Expect firm Wind Slabs near & above treeline with a high likelihood of reacting when disturbed. Large Avalanches are probable today.

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 Storm Slab will keep increasing with more snow today. The Storm Slab scenario could be over 4' in some wind protected areas & gaining in density. Where you travel today, account for the depth of the Slabs & the consequences associated with avalanches that could occur around you.

Avalanche Character 3: 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.

Consistent winds have formed large & fickle Cornices which are highly reactive. Near & Below Treeline exist Cornices with sharp edges & thin to thick wind features. Whether above or below you Cornices can release without warning & entrain too much snow for survival in the event.

Snowpack Discussion

Rain Tuesday into Wednesday had effected the snow with rapid intensity, washing away snowpack in areas below 8000'. Although when the temps fell below 0C low density snow began to collect with astonoshing depth. Yesterday around 8500' over 45" of new snow was light & able to be blown around easily. Major drifting & Cornice formation was observed, with one large Slab Avalanche able to be seen. Storm Slabs will gain density today & may exhibit the ability to fracture when ridden over. Wind Slabs will be firm in some areas & could show signs of instability & remote trigger potentials. Beneath the blower powder is a moist & gooey subsurface with capillary action diffusing water into the snowpack.

recent observations

~Deep powder conditions from below 7000' to far above 8500' where winds haven't consumed or transported snow.

~Recent Avalanche Activity in the form of: Loose Dry, Loose Wet (previous), Wet Slab (previous), Wind Slab & Storm Slab

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 16 deg. F.
Max. temperature in the last 24 hours: 21 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: 8 inches
Total snow depth: 109 inches
weather

Today the snowfall will continue with mostly cloudy skies. Colder than average temperatures will persist as we grab another storm today of shorter duration & lower intensity. Blowing snow & strong wind gusts could create low visibility issues. Stacking storms are on tap for the week with a lull on Tuesday. Looks like rain is off the menu for now with diminishing winds. 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Saturday Saturday Night Sunday
Weather: Mostly cloudy with snow. Snow Level Below 7000' Mostly cloudy with snow. Snow Level Below 7000' Mostly cloudy with a chance for snow. Snow Level Below 7000'
Temperatures: 16 to 26 deg. F. 5 to 10 deg. F. 13 to 21 deg. F.
Wind direction: Southwest Southwest West
Wind speed: 20 to 35 mph; gusts to 50 mph 15 to 25 mph; gusts to 45 mph decreasing to 30 mph late 15 mph; gusts to 25 mph
Expected snowfall: 3 to 7 in. 2 to 5 in. 1 to 4 in.
For above 10000 ft.
  Saturday Saturday Night Sunday
Weather: Mostly cloudy with snow. Snow Level Below 7000' Mostly cloudy with snow. Snow Level Below 7000' Mostly cloudy with snow. Snow Level Below 7000'
Temperatures: 9 to 15 deg. F. 0 to 5 deg. F. 6 to 11 deg. F.
Wind direction: Southwest West shifting Southwest West
Wind speed: 40 to 55 mph decreasing to 30 to 45 mph later; gusts to 80 mph 25 to 35 mph; gusts to 60 mph shifting SW 15 to 30 mph; gusts to 40 mph late 15 to 25 mph; gusts to 35 mph
Expected snowfall: 3 to 7 in. 2 to 5 in. 1 to 4 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.