THIS SNOWPACK SUMMARY EXPIRED ON February 14, 2015 @ 11:57 pm
Snowpack Summary published on February 12, 2015 @ 11:57 pm
Issued by Adam Babcock - Bridgeport Avalanche Center
Avalanche Character 1: Normal Caution
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Use normal caution when travelling in the backcountry.

Individual slope and avalanche path assessment is essential with the incredibly variable conditions.  Watch for increasing wet loose avalanche danger as daytime warming peaks.

Snowpack Discussion

BWRA Update:  The BWRA is still closed to motorized travel.  While there is enough snow to ride the high-elevation cirques, the access routes are thin, and getting thinner by the day.  There is not enough snow at our designated measurement location to open the BWRA as per the management plan.  Both Highway 108 and Leavitt Lake Road are melting out rapidly.  CalTrans has not opened the second gate, which means parking vehicles at Brownie Creek and riding on pavement for 2-3miles.

Discussion:  The Feb 6-9 storm dropped a maximum of 26" of snow in the BWRA, though you wouldn't know it to look at the thin snow cover (also, Leavitt Lake Snotel site is somewhat wind affected).   A couple rain events during the storm and recent warming have settled the new snow dramatically, so the new layers really only amount to 10-12" at best.

The snowpack in the BWRA is a mixed bag of melt-freeze crusts, rain glazing, surface windslabs, facet layers, and supportive mid-pack slabs.

There was a natural avalanche cycle associated with the storm including wet slabs running on old snow and wind slabs failing on a within-storm boundary.  We've had a couple reports of collapsing in the BWRA, and have found faceting immediately below the most recent rain/melt-freeze crust on shaded aspects.  

Yesterday was one of the warmest days we've had this year in the BWRA with a max temp of 55degF at 9600' and a low of 42degF overnight.  We observed some roller balls and a small (D1) wet loose avalanche on a SE aspect that may have been triggered by skier activity.  No other natural or human triggered avalanches have been observed since the storm event cleared out on Monday afternoon.

Soft windslab overlying rain glaze is the most prevalent surface condition near and above treeline in the BWRA.  This combination causes sled tracks to spin freely during steep climbs and feels like dust-on-crust to ski in most places.  This windslab/rain glaze combo, and the other layers associated with the storm, appear to have bonded well and show little propensity for failure (counterintuitively).

The Bottom Line:  The storm slabs that did not slide during the event are showing little propensity to do so now - they appear to be gaining strength.  Watch for wet snow surface instabilities as daytime temperatures continue to set record-highs and nighttime temps remain in the 40s.  Evaluate steep terrain features (37-degree slope or greater) very carefully, as cold, dry facet layers and windslabs have been observed on shaded aspects, and steep features on sunny aspects are prone to wet loose avalanches.

recent observations

Column tests show failure planes in the surface windslab and the facets developing below the most recent crust.  These failure planes have shown little propensity for propagation.  Column tests cut all the way to ground show very difficult failures or no results.  On small test slopes, we have not been able to replicate failures observed in the natural avalanche cycle during the storm.  Even kicking windslab between two skin tracks has not yielded any results.  Increasing roller-ball activity and one small wet loose avalanche indicate surface wet loose instabilities are increasing.

weather

Warm, dry weather will persist through Saturday, then cooling slightly early next week as a cold front crosses the Great Basin well east of us.   A chance of precipitation starts on Thursday.  The cooling will be minor and temps will still be above average for this time of year.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Thursday Thursday Night Friday
Weather: Sunny Clear Sunny
Temperatures: 52-58 deg. F. 32-38 deg. F. 50-58 deg. F.
Wind direction: South Southwest
Wind speed: 10-15mph in the afternoon 10-15mph Light
Expected snowfall: 0 in. 0 in. 0 in.
For above 10000 ft.
  Thursday Thursday Night Friday
Weather: Sunny Clear Sunny
Temperatures: 48-56 deg. F. 34-40 deg. F. 42-52 deg. F.
Wind direction: South Southwest West
Wind speed: 10-15mph in the afternoon 10-15 10-15 in the morning becoming light
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.