Snowpack Summary published on April 16, 2021 @ 5:32 pm
Issued by Arden Feldman - Bridgeport Avalanche Center

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General Spring Avalanche Statement

The BWRA closes this weekend and this will be our final snowpack summary of the season! Avalanches will continue to occur until the snow melts out completely.  Expect to encounter wet snow avalanche problems including loose wet avalanches, wet slab avalanches, and cornice failures. When spring storms impact the region, look out for both wind slab and storm slab avalanches. Continue to do your own localized snowpack assessments and use safe backcountry travel practices.

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.

Spring and wet snow avalanche problems go hand in hand. Strong spring sunshine, warm temperatures, and rain on snow events create unstable wet snow including loose wet avalanches, wet slab avalanches, and cornice falls. The snowpack refreezes at night and the refreeze may be shallow or deep depending on the night-time air temperature and cloud cover. After a solid freeze at night, the snowpack will warm up and become increasingly unstable as the day goes on. Factors that influence how quickly the snow surface warms up include cloud cover, snow characteristics, slope aspect, slope angle, and the elevation of the terrain.  After warm nights above freezing, the snowpack may be unstable first thing in the morning. Several consecutive non-freezing nights are a significant red flag for wet avalanche hazards. Check weather station data to find out overnight temperatures. 

 

Watch out for wet snow avalanches especially when dry snow gets wet for the first time. Fresh snow quickly gets wet and natural and human triggered loose wet avalanches will often occur quickly after warming. Wet slabs occur when melt water percolates down to weak layers in the snowpack for the first time. They are very hard to predict. Use extra caution after significant rainfall or a couple of days of rapid melting without freezing nights. 

 

While traveling in the backcountry this spring be on the lookout for signs of wet snow instability like rollerballs or pinwheels, wet snow deeper than your boot top, rain on snow, and natural or human triggered avalanches. Make sure to assess the snowpack and use these clues to avoid steep slopes when they are too wet. Wet snow avalanches can be powerful, destructive, and very dangerous. However, even a small avalanche in extreme terrain can have serious consequences. Getting out early in the day and making careful observations and conservative terrain choices can keep you safe.  

 

Cornices may be small this year but they still pose a hazard. Give a wide berth to cornices and make sure you’re standing on solid ground when on corniced ridgelines; they can break further back than you might expect. Avoid traveling underneath cornices when the snow is not frozen solid. A falling cornice can be very hazardous and potentially trigger a larger avalanche beneath.

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.

Spring snowstorms can bring increased avalanche hazards from wind slabs and storm slabs. Pay attention to snowfall totals and wind directions. The wind can rapidly load snow onto leeward aspects, making them more unstable. Signs of instability include cracking and collapsing, signs of wind drifted snow, and recent avalanche activity. The fresh snow is most unstable during and immediately after the snow falls. Conservative terrain selection is essential during this time. Also remember that when the sun comes out after a storm and the dry fresh snow warms, snow becomes unstable.

Make sure to continue practicing safe backcountry travel practices this spring. Travel with a partner, only expose one person at a time to avalanche terrain, and carry rescue gear - beacon, shovel, and probe.

Snowpack Discussion

Thank you to everyone who supported the Bridgeport Avalanche Center this season. We have had a great season despite low snow conditions and are already looking forward to next year. The BWRA and other areas in the Bridgeport region are still accessible to non motorized skiing and riding. Don’t let your guard down this spring; continue to practice safe backcountry travel practices. Have a safe and enjoyable spring and summer and see you next year!

weather

Check the NWS Reno Mountain Weather Forecast for additional weather resources this spring. Also check the NRCS SNOTEL website for weather station data including snowfall totals and temperatures.

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.