THIS SNOWPACK SUMMARY EXPIRED ON January 20, 2017 @ 1:47 pm
Snowpack Summary published on January 18, 2017 @ 1:47 pm
Issued by Kyle Van Peursem - Bridgeport Avalanche Center

bottom line:

** The NWS has issued a winter weather advisory for our region from 7pm Wednesday through 7 am Thursday**

The avalanche danger will rapidly rise with the onset of the next series of storms, bringing heavy snow and strong winds. It is recommended to stay off and away from slopes steeper than 32 degrees during this time and give the new snow time to bond to the underlying surface.

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.

As usual for the Sierras, the next series of storms will be accompanied by strong SW winds. These strong winds, combined with up to 20" of new snow through Thursday, will load NW-N-NE-E facing slopes in the BWRA, including slopes above Leavitt Lake. The best travel advice will be to stay off and away from these slopes. Avoid areas of wind slab by avoiding slopes that accumulate blowing snow, new wind pillows, and new cornice formations.

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.

Storm slabs will begin to form Wednesday evening and will grow through the night into Thursday with up to 20" of new snow expected in the BWRA. This snow will fall on weak faceted surface snow and surface hoar in sheltered locations and will be very reactive. Higher up, these weak surface layers are not as prevalent but it will take some time for the new snow to bond to the old snow surface. Your best bet is to stay off slopes steeper than 32 degrees during and after the storm, giving time for the new snow to stabilize.

recent observations

I was up in the BWRA on Tuesday and found a variety of snow surfaces, including large surface hoar in the meadows near the Leavitt Lake Road junction. Higher up in the BWRA these weak snow surfaces were not present. I saw no visible signs of instability with the exception of some wet snow rollers on sun exposed slopes. There was a layer of softer snow that was propagating in my stability tests and this layer may be reactive with an additional load of snow.

weather

High pressure breaks down and an active pattern will dominate our weather through the weekend. A series of 3 separate storms are forecasted to impact us, with the first one lasting from Wednesday through Thursday bringing up to 20" of snow to favored locations in the BWRA. Another storm in forecasted to move through on Friday bringing an additional 20" by Saturday afternoon. A colder and more potent storm will move in on Sunday through Monday bringing the potential for up to 30-40" of additional snow. Total snowfall through Monday in the BWRA is looking to be between 70-80 inches!

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: MOSTLY CLOUDY THEN BECOMING CLOUDY. SLIGHT CHANCE OF SNOW THROUGH THE DAY CLOUDY. CHANCE OF SNOW IN THE EVENING, THEN SNOW AFTER MIDNIGHT. CLOUDY. SNOW LIKELY IN THE MORNING, THEN CHANCE OF SNOW IN THE AFTERNOON
Temperatures: 37 TO 42 deg. F. 18 TO 23 deg. F. 25 TO 31 deg. F.
Wind direction: SW SW SW
Wind speed: 15 TO 25 MPH. GUSTS UP TO 60 MPH 20 TO 35 MPH WITH GUSTS TO 70 MPH 20 TO 30 MPH WITH GUSTS TO 60 MPH DECREASING TO 10 TO 15 MPH WITH GUSTS TO 30 MPH IN THE AFTERNOON
Expected snowfall: UP TO 1 INCH in. 2 TO 8 INCHES in. 1 TO 5 INCHES in.
For above 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: CLOUDY. SLIGHT CHANCE OF SNOW IN THE MORNING. CHANCE OF SNOW IN THE AFTERNOON. CLOUDY. CHANCE OF SNOW IN THE EVENING, THEN SNOW AFTER MIDNIGHT CLOUDY. SNOW IN THE MORNING, THEN CHANCE OF SNOW IN THE AFTERNOON
Temperatures: 33-39 deg. F. 12-18 deg. F. 17-25 deg. F.
Wind direction: SW SW SW
Wind speed: 20 TO 35 MPH. GUSTS UP TO 60 MPH INCREASING TO 85 MPH IN THE AFTERNOON 35 TO 55 MPH WITH GUSTS TO 100 MPH. 30 TO 45 MPH WITH GUSTS TO 85 MPH BECOMING WEST 15 TO 25 MPH WITH GUSTS TO 45 MPH IN THE AFTERNOON
Expected snowfall: UP TO 1 INCH in. 6 TO 12 INCHES in. 2-5 INCHES 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.