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image of snowpit from Mt Blackmore, NE facing, 9185', HS almost 5 ft

Snowpit profile from Mt Blackmore, NE facing, 9185', HS almost 5 ft

The wind yesterday did a number on the snowpack. All aspects and elevations were affected. The most noticeable problem was the large drifts that formed across the landscape. They were not touchy, but if one popped off, it would carry a lot of volume. The secondary problem caught me by surprise. We stopped and dug on a NE facing slope around 7,800 ft. - north of Texas Meadow. HS was roughly 150 cm's. The wind slab on the upper portion of the snowpack did not produce unstable test results but got 2 ECTP's on the basal facets. 

Wind slab around 3-12" deep. NE aspect at 8,000 feet. Occurred sometime on January 8th.

Avalanche Activity

We spotted 6-7 storm slabs that failed about 8-10 inches deep. There were 3 on the East face Blackmore, 1 on the north face, 1 on north facing flank, and 1 notable one in a steep below treeline cirque ENE facing (this one broke ~400 ft wide). A possible 7th was down the Fox creek drainage. It seemed a bit random where they happened and didn't. They likely occurred sometime late yesterday afternoon during snowfall and high winds. This instability should be mostly stabilized by tomorrow.

We didn't see any avalanches that broke deeper in the snowpack

Other signs of instability 

no collapsing or cracking

Skiing/riding quality 

5 star deep powder and hard trailbreaking, aka trenchtown

Snowpack

We had limited time and only dug one snowpit (attached profile image). We'd like to go back and poke around in some shallow rocky areas. Pit attached. General impression is that it is very deep, and mostly strong. The Shower Falls SNOTEL is at 124% of median swe.

Early December facets have gained a lot of strength, and stability is moving in the right direction. With so much new snow (and more coming Friday/Saturday), I worry about finding a trigger point in a thinner area and then causing an avalanche to break widely into deeper areas. After the Fri/Sat storm if no more snow or wind come for a little bit of time, stability should improve very quickly

Note

The photo of snow on the sign post really shows how snowfall has been steady, slow, and non-stop. My hunch is that initially snow piled up on top of the post. Then it began to sag (or creep) to one side but slowly enough to not break. With each storm a little more snow was added and the pile of snow crept more to the side. Cool.

Went snowmobiling north of Cooke City today near Round Lake. I saw about 20cm of new snow. I also saw some avalanches. There were a couple on E Henderson, one that I think happened today, a few on E Sheep Mountain, some shallower avalanches, and plenty of loose dry snow moving around in the steeps. Here are some photos. Some looked like they were from today, some are older. Lots of evidence of wind from the past day or so. 

Hello! Wanted to let you know that the Beacon checking station at the trailhead for Beehive hasn’t been working the past week or more. Doesn’t go green when you pass it. You may already be aware but I thought I’d mention it.
Thanks for what you do!!!

OVC with 10k cloud ceiling in the morning (S-1) which cleared to BKN high clouds by 1pm. No signs of wind transport from the previous 24hrs (tree tops holding snow, little/no snow surface clues at the prayer flags and below). 

We took a quick look at the upper ~1m of the snowpack: generally non-consolidated fist-hardness snow. Small, dry-loose slides were observed in Going Home Shoot and on the west facing wall of Middle Basin. We were able to move the top 5-10cm of snow in short, occasional sluffs but did not experience any other signs of instability. No other signs of avalanche activity could be spotted in the area. By 3pm, wind on the summit of Lone Peak was transporting lots of snow.

The GNFAC weather station at the top of Sawtelle provides wind, temperature and relative humidity information for forecasting (when it's not covered in a foot of rime ice. Photo: GNFAC