Saturated Base Early in Season

Hey everybody, I wanted to make a couple quick observations and ask some followup questions about how the recent weather events may effect our snowpack for the upcoming season.

Quick summary: Approximately 3 inches of precipitation fell throughout the region last week. Most of, if not all, of this precipitation fell as rain. Snow levels were well above summit peaks.The rain event resulted in a reduced snowpack (15-20 inches) and increased SWE's.

Avalanche Canada Kootenay Boundary has a good picture of a pit dug in this saturated snowpack that is worth a look if you haven't experienced it first hand (Description: http://www.avalanche.ca/forecasts/kootenay-boundary, Photo: http://www.avalanche.ca/mountain-information-network/submissions/02bbd63e-a463-493a-a393-0f7e9a03c44a).

Two rain crusts are visible in the photo and you can see how saturated the column is from where the tester punched the snow. It's not clear from the photo if water percolated to the ground surface.

I was just wondering what people's thoughts were on how a saturated base and rain crust might effect the snowpack going forward. The rain crust will obviously need close observation as new snow begins to bond but could there be some other concerns with an excessively saturated base? Might it be a good thing to have such high, consolidate SWE's at the base?

Thanks
 
Hey everybody, I wanted to make a couple quick observations and ask some followup questions about how the recent weather events may effect our snowpack for the upcoming season.

Quick summary: Approximately 3 inches of precipitation fell throughout the region last week. Most of, if not all, of this precipitation fell as rain. Snow levels were well above summit peaks.The rain event resulted in a reduced snowpack (15-20 inches) and increased SWE's.

Avalanche Canada Kootenay Boundary has a good picture of a pit dug in this saturated snowpack that is worth a look if you haven't experienced it first hand (Description: http://www.avalanche.ca/forecasts/kootenay-boundary, Photo: http://www.avalanche.ca/mountain-information-network/submissions/02bbd63e-a463-493a-a393-0f7e9a03c44a).

Two rain crusts are visible in the photo and you can see how saturated the column is from where the tester punched the snow. It's not clear from the photo if water percolated to the ground surface.

I was just wondering what people's thoughts were on how a saturated base and rain crust might effect the snowpack going forward. The rain crust will obviously need close observation as new snow begins to bond but could there be some other concerns with an excessively saturated base? Might it be a good thing to have such high, consolidate SWE's at the base?

Thanks
Typically this would be a sign of stability eventually, unless there is a very slippery rain crust(no rain to snow transition, long dry period after rain with cold and warm weather alternating). At least that's what i am hoping for.
 

PowderPanda

Staff member
Nate,
I was pretty tickled when I saw this post last night. Thanks for thinking and posting!! Love to see this type of content!

So basically what WordBird said. This rain reset the snowpack. Now, the determining factor will be what type of layer was created before the new snow fell. 1. if the snow came in warm then cooled, the warm new snow will bond better to that top crust layer. 2. If the mtn's super cooled as the snow came in, you have a crust layer that will act as a possible concern layer, depending on time as it can connect together.
This is where it is important to keep a notebook to record your snow pit info through the season. You'll know there is a Nov crust layer there to look at as the new snows come in.. Eventually the snow will be so deep you won't dig that far. By that time, you will already know if that crust layer consolidated or is still a potential concern. Every so often it is still important to find a spot to dig deep... however that is not practical every time you go out.

Note: I wrote this before reviewing those links you gave. So, Canada many times has a more complex snow pack due to them being just a tad North, the snow level will dip lower than us much of the time, then up and back down. As I see they had the first snow from a few weeks ago, then rain, then snow, then rain then snow again.
From what I've seen and been told thus far, we just got rain (up to 6" at Schweitzer basin) before it stopped. This weekend will be good to get out and dig a pit to see what we have down here.
As of yet, IPAC has not started forecasting, I'll have to see what they have seen thus far in their journeys.


Another beauty.. to relay your findings on IPAC Obs and right here for our members to see what others are seeing!!

Cheers!
 
At Schweitzer this last weekend we ski cut the south bowl and didn’t get anything to slide, the crust is about as hard as the rocks that are poking up through it but the snow on top is nice. I would still take the time to assess how the new snow is bonding to the crust before skiing anything steep, just because I didn’t get results doesn’t mean that things are safe everywhere. It looks like things might be clear and cold for awhile so facets might start to develop if this weather keeps up, look for signs of surface hoar ( feathery looking crystals growing on the surface) or sugary snow at the base of the snowpack (depth hoar). Those could create persistent weak layers that might be a problem once we get more snow. If you see them try to track what they do throughout the season and try to locate them when you dig future pits. Have fun out there!
 

PowderPanda

Staff member
[quote="Skibumhiggins, e![/quote]

Thanks for the insight Higgins!!! We appreciate the info you bring every season.
 
Wife & I have been out hitting West Bowl to Uleida...not as good as before the warm up, but pretty nice.
Snow seemed to be bonding better the past 4 days or so...Slight sun crust from Sunday on lower Southern exposures, below 5,500'... very skiable, however...A bit more snow up north in PL area...
Here's a scenario to fret about...These cold temps will create even larger surface hoar over the next few days...enjoy, until it buried by the next storm...The current layer of powder is sitting on the rain crust...definitely not scratchy, but real firm...this will rot the newer surface snow on the firm surface out quickly as the firm layer will act like a shallow snow pack...So, with the next storm we would have new snow weighting the thick surface hoar and all sitting on the rain crust...
In the meantime, the snow is excellent.
 
Hey PP...
I simplify things and just call it the "Thanksgiving Crust"...easier to remember for an old guy than a date...Now a new sun crust is forming. It's been sunny up high (not that you'd know it down at the lake!) and it has melted the surface hoar from dime-sized to glop. Skiing still pretty good away from where sun has hit (think Northerly aspects). Big open scree fields are probably not as covered as they seem. Some people ignore that, much to the chagrin of their ski bases...Might even rip a ski off mid-turn...I hear...
Winter is still coming, so be safe out there, plenty of season left!
Let me know if you are up my way PP...
 
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