Observation – 3/19/2014 – Snowshed Mountain, Flathead Range

March 19, 2014 Observations from a tour in the Central Flathead Range:

Objectives: to investigate the snowpack above the most recent rain/snow lines (3/14 and 3/16), search for deeper crust/facet combos, recent and older wind slabs and/or other instabilities; and find fun, reasonably safe skiing.

General info:

Camped at 2100 meters on night of 3/18.  Weather that afternoon had included periods of intense snow showers (up to 3cm/hour) with light and variable winds.  Temp at 17:00 was -6 degrees C.  Trailbreaking had been arduous above 1860 meters, where the last Sunday’s storm had dumped 30 plus cm of dense snow and a similar amount had fallen Monday through Tuesday.  Below  1650 meters trailbreaking had been easy, with 10-15 cm of new snow on top of a supportive crust.  (Below the crust was isothermal mush.)  Climbed on low-angle N-facing slopes in the trees and experienced no whumpfing or cracking.  Above 2100 meters trailbreaking was considerably easier in lighter density snow.

Avalanche info:

Saw no evidence of recent natural avalanches on wind-loaded terrain near Mount Adams, peak 7798, or anywhere else, except for small sluffs on steep solar-affected slopes. (On descent, at 17:15 observed a small recent natural avalanche at 2000 meter elevation with a crown 10-15 cm deep and 30 meters wide that ran 30 meters.  This was on a 38 degree rollover  in a NE-facing gully that has a substantial wind-funnel/fetch immediately above it.   (See attached photos.)

Weather info:

 @ 11:30 am @ 2235 meters: -10 degrees C. Partly cloudy.  Gusty SW winds up to 10m/s.

Observed moderate snow transport onto N through E facing slopes at my location, though big snow plumes were visible off the higher peaks, and wind loading was apparent in an adjacent NE-facing corniced bowl. (photo)

Test Profile info:

NW-facing 35 degree slope near the ridgetop at 2235 meters. 

H.S. Excavated down 200cm, and buried a 240cm probe below that without hitting ground.

Boot penetration: 75cm.  Ski penetration: 32cm.

Hardness, measured from the surface: 0-40cm: F; 40-70cm: 4F; 70-110cm 1F; 110-200cm P. (photo)

Did not find rain crusts in top 200cm of snow.  Did find a few density changes not revealed in hand hardness tests.  (photo)

Test results:

2x CTE @ 20cm Q3 (scores: 5 and 7)

2x CTH @ 40cm Q3 (scores: 24 and 25)

ECTN 10 @ 20cm

Ski cut small moderately wind-loaded rollovers up to 40 degrees with no results.

Skied NW through N-facing wind-sheltered slopes up to 35 degrees without incident.  Skiing quality was excellent. 

At 2100 meters it was -6 degrees C and snowing at 1cm/hour with moderate SW winds at 17:00

At 1160 meters it was 2 degrees C and snowing at less than 1/cm per hour at 18:00.

 

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