Snowpack Summary published on March 29, 2017 @ 8:58 am
Issued by Kyle Van Peursem - Bridgeport Avalanche Center

bottom line:

The avalanche danger will increase during the afternoon on Wednesday and Saturday as sunny skies and warm temperatures will lead to possible loose wet avalanches.  On Thursday and Friday, strong winds switching from the SW to NE will load most exposed upper elevation slopes leading to the potential of wind slab avalanches.

Avalanche Character 1: Loose Wet
Loose Wet avalanches occur when water is running through the snowpack, and release at or below the trigger point. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.

On Wednesday and Saturday, warm temperatures and sunny skies will quickly heat up the snow surface leading to the potential of loose wet avalanches on E-SE-S-SW-W facing slopes, late morning to late afternoon, respectively.  Though these will most likely be small, enough snow could be entrained to push someone off their sled and could be dangerous in high consequence terrain.  Stay off of slopes steeper than 35 degrees where rollerballs and pinwheels are present.  

Avalanche Character 2: 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.

On Thursday, strong SW winds will impact the BWRA as a quick moving front comes through.  Though not much dry loose snow is available for transport, any available snow will load NW-N-NE-E facing slopes leading to isolated wind slab pockets.  We already saw a small human triggered wind slab avalanche in Voodoo Bowl earlier this week so the potential of triggering one of these on slopes steeper than 35 degrees will be possible.  On Friday, strong winds will switch to the N/NE and will load atypical slopes with a SE-S-SW-W facing aspect.

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.

Large overhanging cornices are present in numerous locations across the BWRA.  A few have already collapsed including one in Leavitt Bowl.  These are unpredictable and can break back much further than expected.  The best strategy is avoidance and limiting the amount of time below these features.  If traveling on ridge lines, keep a wide berth and stay away from the edge of cornices.

recent observations

On Tuesday, generally stable conditions were observed in the BWRA with cold morning temperatures limiting and delaying the amount of heating during the day.  A variety of snow surfaces were observed including sun crusts, supportable wind boards, and dry unconsolidated snow on steep northerly facing slopes.  A small human triggered wind slab avalanche was observed in Voodoo Bowl, which likely released on Monday.

weather

As of 7 am on Wednesday, temperatures are already well above freezing in the BWRA with clear skies.  Temps will rise into the mid to upper 40's though clouds will increase this afternoon out ahead of a quick moving storm.  On Thursday, the storm will bring strong SW winds and a few inches of snow.  As the storm departs winds will switch to the N/NE on Friday with gusts still reaching 50-60 mph.  High pressure builds in over the weekend with sunny skies and well above freezing temperatures.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: Sunny with clouds increasing in the afternoon Partly cloudy then becoming mostly cloudy Mostly cloudy then becoming cloudy. Snow showers likely in the morning. Slight chance of thunderstorms through the day. Chance of snow showers in the afternoon.
Temperatures: 47 to 52 deg. F. 29 to 35 deg. F. 34 to 43 deg. F.
Wind direction: NA West. Southwest after midnight Southwest switching to northwest
Wind speed: Light winds. Gusts up to 25 mph in the morning 10 to 15 mph increasing to 20 to 30 mph after midnight. Gusts up to 65 mph 30 to 45 mph with gusts to 100 mph. 25 to 35 mph with gusts to 80 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 1-2 in.
For above 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: Sunny with clouds increasing in the afternoon Partly cloudy then becoming mostly cloudy Mostly cloudy then becoming cloudy. Snow showers likely in the morning. Slight chance of thunderstorms through the day. Chance of snow showers in the afternoon.
Temperatures: 42 to 48 deg. F. 24 to 30 deg. F. 29 to 35 deg. F.
Wind direction: North West West
Wind speed: North 10 to 15 mph with gusts to 25 mph in the morning becoming light. West 10 to 15 mph increasing to 35 to 55 mph after midnight. Gusts up to 80 mph. West 40 to 60 mph. Gusts up to 110 mph decreasing to 95 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 2-3 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.