THIS SNOWPACK SUMMARY EXPIRED ON January 23, 2017 @ 9:22 pm
Snowpack Summary published on January 21, 2017 @ 9:22 am
Issued by Kyle Van Peursem - Bridgeport Avalanche Center

bottom line:

** The NWS has issued a winter storm warning for our area valid through 4 am Monday **

Today (Saturday, 21-Jan): Natural avalanches will be possible and human triggered avalanches will be likely in the BWRA on slopes steeper than 35 degrees due to recent heavy snowfall on all slopes and wind loading on NW-N-NE facing slopes. 

Sunday and Monday (22-23 Jan): Dangerous avalanche conditions will exist in the BWRA due to very heavy snowfall and gale force winds from the SW.  Natural and human triggered avalanches will be likely on all slopes steeper than 35 degrees.

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.

Very heavy snow combined with gale force winds from the SW will rapidly load NW-N-NE facing slopes, leading to likely natural and human triggered avalanches in the BWRA.  Large, destructive, and widespread avalanches will likely run further down slope than expected.  It is advised to remain off and away from all wind loaded slopes for a few days and give these wind slabs a chance to stabilize.

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.

Up to 4' of new snow is expected Saturday night through Monday morning in the BWRA.  This will place a huge amount of additional weight on an already stressed snowpack, leading to certain human triggered and natural avalanches.  There is a buried rain crust which will be 5-7' below the surface by Monday and was shown to be fragile in stability tests.  Shallower avalanches failing in the new storm snow could have the potential to step down to this rain crust and trigger a much larger and destructive avalanche.  Avoiding all avalanche terrain, especially the bottom of large avalanche paths, will be key to staying safe through Monday. 

recent observations

We rode up Hwy 108 and part way up Leavitt Lake Road on Thursday and found 2' of new snow sitting on top of a rain crust which formed at the beginning of the storm on Wednesday.  We also observed a few storm slab avalanches on small convex slopes.

weather

Since Wednesday, 35" of snow was measured at the Sonora Pass SNOTEL station and 47" was measured at the Leavitt Lake SNOTEL station.  Light snow is expected today ahead of a very strong and potent storm coming in tonight lasting through Monday morning.  An additional 50" of snow is forecasted to fall in the higher elevations in the BWRA.  Storm totals since Wednesday could top out around 100" by Monday in parts of the BWRA!  This may be the last storm for a while as models are showing a persistent area of high pressure building in over the West coast next week, lasting at least through the first week of February.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Saturday Saturday Night Sunday
Weather: CLOUDY. SCATTERED SNOW SHOWERS CLOUDY. CHANCE OF SNOW IN THE EVENING, THEN SNOW AFTER MIDNIGHT CLOUDY. SNOW
Temperatures: 23 TO 29 deg. F. 19 TO 24 deg. F. 25 TO 30 deg. F.
Wind direction: WEST SOUTH SOUTH
Wind speed: 15 TO 25 MPH WITH GUSTS TO 50 MPH 15 TO 25 MPH. GUSTS UP TO 45 MPH INCREASING TO 60 MPH AFTER MIDNIGHT 20 TO 35 MPH WITH GUSTS TO 85 MPH
Expected snowfall: UP TO 5 in. 10 TO 16 in. 20 TO 28 in.
For above 10000 ft.
  Saturday Saturday Night Sunday
Weather: CLOUDY. SNOW SHOWERS IN THE MORNING, THEN SCATTERED SNOW SHOWERS IN THE AFTERNOON CLOUDY. CHANCE OF SNOW IN THE EVENING, THEN SNOW AFTER MIDNIGHT CLOUDY. SNOW
Temperatures: 17 TO 23 deg. F. 14 TO 20 deg. F. 19 TO 24 deg. F.
Wind direction: WEST SOUTHWEST SOUTHWEST
Wind speed: 20 TO 35 MPH WITH GUSTS TO 60 MPH 20 TO 30 MPH WITH GUSTS TO 60 MPH INCREASING TO 30 TO 45 MPH WITH GUSTS TO 90 MPH 45 TO 60 MPH. GUSTS UP TO 110 MPH INCREASING TO 125 MPH IN THE AFTERNOON
Expected snowfall: UP TO 4 in. 12 TO 18 in. 25 TO 30 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.