Posted 5:35pm 12-19-2014
Welcome to the 1st of many “Weekend Updates” this season. If you’re new to this product we put this out each Friday afternoon/early evening when we are using the US 5 Scale Danger Rating system. We believe there is a lot that can change in the 12 hours from the Friday morning advisory and the evening Update, particularly with the weekend weather predictions. Allowing one or two model runs (depending on which MOS model) to come out during the day can really make a difference. Our intention is to provide the latest data we are aware of so you can make better travel plans for your weekend.
A few days ago I wouldn’t have predicted we’d have a High avalanche posting out yesterday and fracture lines peppering the terrain today due to natural avalanches. Why? Because on Wednesday morning the mountain succumbed to a quick burst of unpredicted 2” an hour snowfall rates for 3-4 hours. By 1045 the sweat was rolling off our foreheads wondering if this was going to continue all day, it didn’t. But by midnight on Wednesday the summit recorded 9.5” with an additional 7” by noon yesterday. After my time in the field with Frank today we surmised that areas below the upper part of the summit cone received much less than the 16.5” the Observatory recorded. This is not unusual per se, but it made avalanche forecasting difficult coupled with the complicating cloud cap and no visibility.
The cloud cap today made us wait and hope that visibility would improve so we delayed until late morning when we pushed through the clouds hoping for an undercast. We had brief windows of clarity in Tuckerman to get some pictures before the veil rolled back in. (See more on our facebook page). We will post Huntington shots tomorrow when clear skies prevail.
First picture is Tuckerman’s Right Gully and the Sluice
2nd-Sluice through the Headwall
3rd-Close up of the Lip and the Right-Center Headwall
4th the left Headwall over the Left Gully
We decided that presenting numbers and tests would do little to help due the amount of spatial variability around the mountain. Clearly the pictures demonstrate numerous fracture lines. We think these avalanches occurred naturally, likely late on Thursday a bit before the peak wind of 98mph. Some have reloaded a bit, others have not. If you look closely at the Lip fractures you’ll see a number of small reloaded pockets from sluffs and windloading. Under the Chute fracture just to the right of Left Gully you’ll find less re-loading, but more hangfire and threat above. In between across the Center Bowl you see a mixed bag of scouring, loaded pockets, avalanche bed surfaces, and of course cliffs and ice.
Generally you should see areas fall one avalanche danger rating or more tomorrow. In Tuckerman a skilled traveler can find a climbing route that seasoned individuals would find acceptable in relation to avalanche risk. That said, a group giving no attention to mitigate avalanche risk could find locations with enough instability to respond to human triggers causing an avalanche. Once again, you got it!…….spatial variability.
Often the skill of visual assessment and the clues we can get from using our eyeballs are under estimated. Yes it’s true that stability assessments can require digging, but as in all things rarely does one source of data give you the entire picture. When standing and staring at the terrain ask “why does the snow look like that?” It is somewhat of a hidden or lost art that we should revive. This is regularly highlighted for me on Mount Washington due to how much wind sculpts the winter landscape. Today it was once again an important skill viewing deep runnels, fracture lines in different states of reloading, a thin rimed surface, smooth and creamy areas, rough and punished locales, knocked over brush and floor debris, etc. the list goes on. Check out this book if you’ve never seen it. Ed LaChapelle is one of our avalanche mentors but this book is one of his lesser known works although certainly a winner! I’ll do a book review of it later this week and post on “the pit”. A great resource of a lost visual skill.
Something to remember with weekend weather forecasted to deliver ample sun and low winds, that many avalanche accidents occur in these conditions because we forget to be critical thinkers. Everything just seems so glorious. Beware of the human factors and heuristic traps we can fall into on these blue bird days. The snowpack doesn’t care that it’s beautiful it will do what it’s set up to do. Have a great weekend and check the avalanche advisory in the morning. Chris