Snowpack Summary published on April 22, 2018 @ 8:19 am
Issued by Ryan Lewthwaite -

bottom line:

Heat & intense sun will melt the snowpack at a rate of 2-3" daily. Overnight temperatures are inverted with colder temperatures in the valley bottoms & 40F degrees at Leavitt Lake snotel. All aspects & elevation bands are seeing natural Loose Wet avalanches from the surface melting snow. Skiers & sledders are causing minor sluffs when traveling on steeper terrain. We are checking snow depths, patrolling boundaries & looking for avalanches in the hopes to remain open another week. APRIL 29, 2018 is the projected last day of snowmobiling in the BWRA.

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.

The continuing problem will remain Loose Wet avalanche activity as temperatures are well above April norms. Exposed rock & earth is heating up the surrounding snow & sending melted slush downslope. Overnight lows are only reaching 38F at Sonora snotel while an inversions keeps Leavitt snotel at 40F degrees. As we lose 2-3" daily of the snowpack keep in mind objects & streams are reemerging through the surface. 1:00 to 2:00 PM is prime-time for viewing this type of natural avalanche event.

Snowpack Discussion

Continuous rapid melting is occuring as temperatures remain well above normal. Evening inversions only help the snow turn to water faster. The primary concern for the next few days is the Loose Wet avalanche. The exposed earth emerging, especially dark rock, is decreasing surface albedo. Albedo is the ratio of light reflected vs. absorbed by a surface. The rock are acting as a heater, sending melted snow downhill. The existance of Radiation/Recrystallization has our slopes looking shiny. The sun is penetrating over 8cm into the snowpack & transitioning to isothermal, or near 0C. The Corn & supportable underlayers of the snowpack are creating very good riding in the BWRA!

recent observations

Many Loose Wet avalanches on all aspects & elevation zones. Most avalanches are minor point releases & surface sluffs, some are caused by travelers on steep terrain. Excellent riding conditions exist with the ever-present avalanche awareness on the mind. Snowmobile safe my friends!

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 38 deg. F.
Max. temperature in the last 24 hours: 59 deg. F.
Average wind direction during the last 24 hours: North
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: 0 inches
Total snow depth: 45 inches

Sun & light winds with temperatures well above normal. Afternoon cumulus clouds could emerge with a passing disturbance. A low chance for thunderstorms exists, but stow that knowledge for when you see signs of building clouds. Leavitt Snotel is measuring 40F degrees at 6AM, as we have the second evening of a temperature inversion.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Sunday Sunday Night Monday
Weather: Sunny Clear Sunny
Temperatures: 55 to 65 deg. F. 30 to 35 deg. F. 55 to 63 deg. F.
Wind direction: Southwest West Light winds
Wind speed: 10 to 15 mph; gusts to 30 mph later 10 to 15 mph; gusts to 30 mph becoming light late Light winds
Expected snowfall: 0 in. 0 in. 0 in.
For above 10000 ft.
  Sunday Sunday Night Monday
Weather: Sunny Partly cloudy then becoming clear. Sunny
Temperatures: 48 to 54 deg. F. 26 to 32 deg. F. 48 to 54 deg. F.
Wind direction: Southwest West West
Wind speed: 10 to 15 mph; gusts to 30 mph 10 to 15 mph; gusts to 30 mph becoming light late 10 to 15 mph in the morning becoming light
Expected snowfall: 0 in. 0 in. 0 in.

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.