Heavily wind effected snow in the Sherwins

Mammoth Rock
Submission Info
Saturday, January 11, 2020 - 12:30pm
Red Flags: 
Recent loading by new snow, wind, or rain
Snowpit Observations
More detailed information about the snowpack: 

I went for a quick our above mammoth rock this morning to get an idea of how these extreme winds have been affecting the lower elevations. Unsurprisingly, my evidence gathering started on my drive to the trailhead. Significant flagging was seen on the high peaks in the Laurel lakes and Sherwin creek areas. I also observed some drifted snow on Minaret Rd adjacent to the golf course, where westerly winds had loaded the shoulder with a fresh wind drift about 2’ deep.  Long story short, the wind has impacted surface conditions everywhere I observed today, All in sheltered trees at elevations up to 10,000’ in elevation.  Some impressive mid-slope sastrugi, recent drifting and blowing snow all suggest that the driving force behind this change in surface conditions are a result of the extreme westerly winds that started last night. The soft faceted surface snow many have been finding in sheltered northern aspects was gone, and in its place, I found wind board. While I observed wind compacted snow ranging from .5 cm wind skin to 15cm+ supportable wind board, most of my travels today was on breakable board in the 5cm range. Gale force winds kept me from topping out on the ridge, but it was very apparent that any loose snow on the ridge top was being blown far into the atmosphere. The most concerning wind transport I saw today was occurring mid-slope in sheltered trees and in semi-clear areas with terrain features that encouraged drifting. Miner surface cracking was widespread today. For the most part, this was limited to small dinner plate sized chunks breaking under the weight of my ski or table-sized sheets breaking off of my kick turns.  While I did observe many areas of significant deposit, I was not able to sniff out any reactive wind slabs of concerning size. That being said, there was ample evidence to suggest that one could stumble upon an isolated pocket of wind slab given the right circumstances and terrain characteristics. Numerous hand pits identified the wind board to be in the 4f+-p range depending and largely made up of faceted grains. I suspect the loose near-surface facets recently observed in many shaded and protected areas are making up the majority of snow currently available for transport.

It is worth noting that the most significant hazard I encountered today was during my decent. Skiing in these challenging conditions required deliberate movement and focus. It was not uncommon to encounter hard slick supportable wind board and breakable trapdoor conditions in the span of 15 ft. 

Snowpack photos: 
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Gale Force
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Mostly sunny skies prevailed throughout my tour with air temperatures in the mid 20°s F. Sustained strong Westerly winds made for a brisk adventure today. Gusts were certainly into the extreme realm at times and my balance was challenged more than one.

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