THIS SNOWPACK SUMMARY EXPIRED ON March 19, 2019 @ 7:16 am
Snowpack Summary published on March 17, 2019 @ 7:16 am
Issued by Ryan Lewthwaite -

bottom line:

Todays primary concern is for Loose Wet avalanches on all aspects & elevations. Intense sun & temperature inversions will allow for a lot of melting & sublimating of the snowpack, which can lead to unstable surface snow conditions. Restrict your afternoon riding to areas of low consequence.

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.

With temperatures hovering near 40F (4.4C) this afternoon we can anticipate melting snow to exacerbate Loose Wet avalanches. An overnight temperature inversion has the Leavitt Snotel reading 32F at 6AM, while Sonora Snotel is 9 degrees colder. Look for the obvious clues that surface snow conditions are changing throughout your travels.

Snowpack Discussion

Daytime heating will melt & sublimate the surface of the the snowpack. A temperature inversion could make upper elevation snow conditions wet & loose. Where overnight freezing temperatures have occurred expect a surface melt-freeze crust of varying thickness. In the alpine we found near surface facets just below a 2cm melt-freeze crust which could be touchy but very shallow. Snowmobiles were spitting loose wet snow from their tracks while climbing in steeper terrain but no slabs were failing. Loose Wet avalanches will be very likely this afternoon as we approach 40F. Compression tests were repeated and have shown a density change 32cm deep, taking a hard force to initiate fracture.

recent observations

~3/14 Wind Slabs have stopped growing due to calm winds. No new recent avalanches were observed.

~3/16 Repeatable CTs, conducted during an Avalanche Awareness Class, show a density change 32cm deep but it takes a hard force to initiate fracture. Loose Wet avalanche activity was beginning to appear, in the afternoon, on slopes that get direct sun. Many riders were observed stepping-out into larger terrain with no reports of negative consequences.

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 23 deg. F.
Max. temperature in the last 24 hours: 43 deg. F.
Average wind direction during the last 24 hours: Calm
Average wind speed during the last 24 hours: Calm mph
Maximum wind gust in the last 24 hours: Light mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 101 inches
weather

Continued sunshine & light winds with gradually increasing temperatures each day. Temperature inversions are becoming more common at night & we will barely get to freezing this morning in near and above treeline areas. Tuesday evening is the next chance for precipitation, as two consecutive storms could bring high elevation snow to the Sierra crest. Rain is likely in lower valley areas with a fluctuating snow line between 6000' & 7000'. 

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 then becoming partly cloudy. Sunny
Temperatures: 41 to 49 deg. F. 19 to 24 deg. F. 42 to 50 deg. F.
Wind direction: Light Winds Light Winds Light Winds
Wind speed: Light Winds Light Winds Light Winds
Expected snowfall: 0 in. 0 in. 0 in.
For above 10000 ft.
  Sunday Sunday Night Monday
Weather: Sunny Clear then becoming partly cloudy. Sunny
Temperatures: 34 to 40 deg. F. 16 to 21 deg. F. 34 to 40 deg. F.
Wind direction: Light Winds Light Winds South
Wind speed: Light Winds Light Winds 15 mph in the afternoon
Expected snowfall: 0 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.