With below average moisture in November and Early December the first storm of winter showed up on December 9th. Followed by another shot of snow the week after. This officially kicked off ridable snow for the season in the Northern Wasatch. Yesterday we saw anywhere from 4-10 inches of snow and 1-1.5” of water. Powder Mountain study plot is currently winning with 30” of settled snow on the ground. The warm wet disturbance will continue into today before we see temperatures cool and drier snow start to pile up. Numbers are always in flux but we could see up to 4” of water (SWE) and 40” of snow before we ring in 2022.
So what does all this wind, rain, snow, warm temps, mean for avalanches? Well….. We have proven over the last few days that we do have a lingering persistent slab avalanche problem in the Northern Wasatch. These avalanches are not as well connected as they were last year. These avalanches will be much sparser in distribution which makes them way harder to predict and forecast. On December 24th, we saw to two Persistent Weak layer avalanches failing on October snow in high ~8700ft elevation on N and NE aspects. These were both D2 in size which is due to the connectivity issue I stated earlier. These were both hard slab (HS) avalanches, the slab was created by the strong winds from the past few days. These avalanches are extra scary because the mix of the HS and Persistent Weak Layer type can lure you very far out onto the slab before the avalanche fails, limiting any chance of getting off the slab. These avalanches are also deep in nature even though they may not be wide. Stay alert! I personally am avoiding High Northerly terrain still.
Now what! Well, more snow and wind equals more avalanches. The weight of the new snow and wind should help forecasters have more confidence in their forecasts. Remember that RECENT AVALANCHES is the number one red flag. So if we are seeing avalanches failing on persistent layers now, we will probably see this layer active through the week. So be alert! I will leave you with this. I use the reg flags ALWAYS! I also added a 6th that I like.
Avalanche Red Flags
- Recent Avalanches (Last 48 Hrs)
- Recent Snowfall (12” snow or 1” SWE)
- Strong Winds or Drifting Snow
- Rapid Rise in Temperature or Thaw
- Cracking, Collapsing, or Whoomphing
- Persistent Weak layer Noted in the Public Avalanche Forecast (Kory’s Red Flag)
As I look through these. I can check 5 out of 6 of the red flags, So be weary over the holiday and have fun!
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