THIS SNOWPACK SUMMARY EXPIRED ON December 22, 2017 @ 11:28 am
Snowpack Summary published on December 20, 2017 @ 11:28 am
Issued by Ryan Lewthwaite -

bottom line:

The Bridgeport Avalanche Center is back at it again! We are actively monitoring the BWRA for enough snow depth & coverage to open for snowmobiling. Currently a fast-moving storm is upon us, but sadly it may not produce the accumulation we require for over-snow vehicle travel. Since Thanksgiving our recreation area has seen unseasonably warm & dry conditions with a predominately wind deposited & thin snowpack overall. Our regulations mandate adequate (at least 24") snow coverage must exists in the BWRA before opening to snowmobiling. This limit protects natural resources & critical wildlife habitat; some of which is home to multiple threatened & endangered species. Until further notice the Bridgeport Winter Recreation Area will remain CLOSED & will be closely monitored by our staff. We are glad to welcome two new Winter Rangers to the team Chris & Brett. They have submitted the first snowpack observation of the season & will be assisting me with the Avalanche forecast. Our first Avalanche Education class will be held on January 19th & 20th in Mammoth @ the Community Center. All are welcome to attend the classroom portion, but please register here for the field day.

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.

Old & wind drifted snow, where it exists, is thin & firm. Cross-loaded & Northerly facing slopes are holding pockets of snow deposited nearly a month ago. With new precipitation & gale-force winds expect these areas to develop deep hazardous wind slabs on the older ones.   

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.

A quick blast of snow, wind & cold has arrived for our forecast zone, finally... It could bring us 5 to 10 inches of new precipitation but will be driven by the gale-forced winds gusting to 105 in the alpine! There is no doubt this snow will be moving around the hills & finding its way into terrain features as deposits, likely sitting on slabs formed around Thanksgiving. With strong winds, storm slabs can become much thicker than estimated snow totals.  As usual, these accumulations will need time to settle before safe conditions prevail. 

Snowpack Discussion

A predominantly thin & scoured snowpack exists in the BWRA. Wind deposits on shady & Northern aspects range from 1 to 22 inches in the alpine & bare ground exists almost everywhere below 8800'. The new snow accumulations will make slopes above 35 degrees suspect for avalanches, as it sits upon stout wind & sun crusts. The BWRA will remain CLOSED due to lack of adequate snow coverage. The Bridgeport Avalanche Center will be monitoring the area & snowpack daily.

recent observations

No new avalanches were recorded, but this storm will likely change that. Stay tuned.


A Narrow Cold Frontal Rain system is currently underway in our area. This quick & windy snow storm could bring us some much needed moisture with accumulations of 5 to 10 inches in the higher mountains of the Pacific Crest. Winds will be strong from the Southwest changing to North as the storm moves across the slope. Gusts as high as 105 mph are forecasted! Single digit temperatures will be seen tonight, but a return to high pressure immediately following the frontal passage.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: Cloudy with snow showers Partly cloudy 40% chance of snow showers Sunny
Temperatures: 27 to 33 deg. F. 7 to 12 deg. F. 22 to 27 deg. F.
Wind direction: Southwest becoming west North Light winds
Wind speed: 30 to 45 mph gusts to 90 mph becoming west 20 to 30 mph gusts to 75 mph 15 to 25 mph gusts to 50 mph Light winds
Expected snowfall: 1 - 4 in. 1 in. 0 in.
For above 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: Mostly cloudy with snow showers Partly cloudy 40% chance of snow showers Sunny
Temperatures: 21 to 27 deg. F. 3 to 8 deg. F. 20 to 25 deg. F.
Wind direction: Southwest becoming west North North
Wind speed: 50 to 70 mph gusts to 105 mph becoming west & decreasing 30 to 45 mph gusts to 85 mph 20 to 30 mph gusts to 50 mph increasing 30 to 45 mph gusts to 65 mph after midnight 30 to 50 mph gusts to 70 mph
Expected snowfall: 2 - 4 in. 1 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.