THIS SNOWPACK SUMMARY EXPIRED ON January 15, 2018 @ 11:56 am
Snowpack Summary published on January 13, 2018 @ 11:56 am
Issued by Ryan Lewthwaite -

bottom line:

A bit of disappointment is settling in here at the BAC as we are still CLOSED up at the BWRA & we are cancelling our first Snowmobile Avalanche Awareness Clinic. With the inundation of avalanche education in the Mammoth Lakes area & no field-day component available, we are biting the bullet for this session. Gardnerville, NV on the 2nd & 3rd of February is the next chance to get "Sleducated", please register here. NO new snow to report as avalanche conditions are beginning to subside. We are still concerned with a persistent slab & wind slab instability for the time being. Please keep yourself tuned into the advisory for condition updates.

Avalanche Character 1: Persistent Slab
Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.

The big threat still remains in the form of facets buried mid-snowpack. Potential avalanche activity lingers at this unconsolidated layer which resides predominantly on East through North aspects. Although whumphing in the alpine is widespread the activity associated with this problem has been confined to these E-N loaded aspects & terrain features. The snow mass above the facets is thick enough to produce R2D2 or larger size avalanches when propagated.

Avalanche Character 2: 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.

Winds out of the West through South have left behind the larger deposits of snow seen in the BWRA. Steep & loaded slopes facing East through North have the likelihood of producing remotely triggered avalanches from human activity. Being in or just below the avalanche run-out zone is hazardous. Wind slabs tend to elongate themselves further down the slope with relation to winds & carry potential energy. You could be the instability, transferring a collapse of the slab up to the starting zone.

Snowpack Discussion

Last night was cool & clear, this should add a bit of strength to places where there is a snowpack. The last precipitation we've gained up there fell on the 8th & 9th & a dusting during the day on Thursday. Per usual the winds have lifted up our powder & distributed it wildly across the tundra, with prominent deposits on Eastern aspects. These eastern facing slopes contain wind slabs & buried facets that are gripping our avalanche activity potential. The remnants of two wet slab avalanches, from Tuesday 1/9, are visible from the Leavitt junction & face directly east. Above 9250' drier wind slabs sit above that persistent buried facet layer which, when instigated, may produce R2D2 size avalanches.

recent observations

On Thursday the team saw another, previously unseen, wet avalanche adjacent to the "Repeat Offender" above Leavitt Road. Wednesdays outing produced more whumphing & a glimpse into Leavitt cirque. Through the cloudiness Leavitt cirque showed that it had trouble collecting the wind-driven snow, leaving behind mid-storm crowns that wrapped the feature. The crowns looked somewhat connected & leads me to believe that a major propagation took place. This storm slab instability was coupled with fluctuating rain up high and wet loose & wet slab avalanches.

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 30 deg. F.
Max. temperature in the last 24 hours: 51 deg. F.
Average wind direction during the last 24 hours:
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: -1 inches
Total snow depth: 14 inches

Our MLK weekend will persist with above normal temperatures & dry air. Monday evening will bring a modest change to the pattern with a weak low pressure system. Not much in the way of accumulation is expected from this storm, but wind is always welcoming. Thursday & Friday has a better chance for mountain snow & low elevation rains. The forecasts recently have trended warmer & timing has been tardy.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Saturday Saturday Night Sunday
Weather: Sunny Clear then becoming partly cloudy Partly cloudy
Temperatures: 47 - 53 deg. F. 27 - 35 deg. F. 49 - 55 deg. F.
Wind direction: Light winds Light winds Light winds
Wind speed: Gusts to 35 mph early Light winds Light winds
Expected snowfall: 0 in. 0 in. 0 in.
For above 10000 ft.
  Saturday Saturday Night Sunday
Weather: Sunny Partly cloudy Partly cloudy
Temperatures: 41 - 46 deg. F. 29 - 34 deg. F. 43 - 49 deg. F.
Wind direction: Southeast Becoming Southwest late Light winds
Wind speed: 15 to 25 mph; gusts to 35 mph early 10 to 15 mph late Light winds
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.