Shifty Winds on Trimmer

Location Name: 
Trimmer Peak
Region: 
Luther Pass Area (including Job and Freel)
Date and time of observation: 
Fri, 02/25/2011 - 12:00
Location Map: 
United States
38° 52' 45.0264" N, 119° 55' 45.1956" W
See map: Google Maps
US


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

Significant new snow and wind loading with storm snow weaknesses observed, especially near ridgetops.

Pic: Ski cuts along "Trimmer Bonus" at 8400ft NW of Trimmer produced consistent results within the new storm snow / slab. However, just 50ft below ridge (to north), slab became much less evident and showed no signs of instabilities with mitt pits, ski cuts, and an RB6 EB Q3 down 20cm on a 37 degree slope, N/NW aspect.

Video: Wind transport on top of "Trimmer Bonus" at 8400ft. Majority of snow was becoming airborne, which may explain less slab formation just downslope from ridge.

Approaching the Trimmer plateau along N aspect, slab formation became evident much farther downslope from ridgetop, with shooting cracks on convex rolls and above treewells from 8500 to 9000ft.

At 9000ft on a 34 degree slope N aspect, we had an RB2 WB Q2 down 30cm (storm snow) that upon collapse stepped-down to 75cm at the density change observed from the previous storm cycle - WB again. Although this density change remains intact and reactive here, the older slab above it is 4f+ and not hard as observed elsewhere. Sorry, no video - camera batteries died.

Much of the storm snow appears heavily rimed, with some graupel mixed - but no distinct graupel layers observed.

 

Snowpack photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Winds along ridgetops were SW, yet below ridges winds were distinctly and consistently N/NW. This, combined with Strong winds, was creating complex redistribution patterns.

The day began with less than 1" per hour snowfall, then cleared for about 45 min at noon, then snowfall intensity increased to greater than 1" per hour until our departure at 3pm.