Snow Science Help

So here in Oregon the weather has been very atypical for the past few weeks and I am wondering what to expect from the snowpack. Here's what happened:
December 23rd: thick base of our usual heavy, gloppy, consolidated snowpack
December 24th - January 3rd: Amazingly light pow almost non-stop, periods of high wind, steady temps between 15 - 28F
January 4th: Clear and cold, some wind, occasion sun breaks, mostly just overcast
January 5th to current: Temps go down into the 8 - 19F range, freezing rain for the past 20 hours.
More weather data and forecasts available here: http://www.wrh.noaa.gov/Portland/ then click on Mt Hood or Mt St Helens.

I'm figuring that this heavy crust layer of freezing rain is bad for avy danger. It potentially creates a heavy crust over the light and soft pow layer.
Barely anybody has been out in the BC since the resorts have been soooo damn good (for here), so no skier compaction to speak of. I have no trips planned and would certainly go with an experienced, trained group with all the right gear.

For those that know more than me, what can I expect to find in the Northern Oregon/Souther Washington BC given this info? Anything in particular to watch out for?

Yeah, and the forecast is for more snow. That heavy snow collapsing the frozen rain layer over the light pow layer seems like a potential for big crowns.
What is the likelyhood that naturally occuring slides have reduced future slide potential?

[hijack] What do you think the chances are of my wife landing tonight aroung 10pm in Portland with the weather being how it is there?? Apparently they cancelled some flights yesterday. [/end hijack]

Internship interview, I hope she makes it.

Keep your eyes on this as well:

December 23rd: thick base of our usual heavy, gloppy, consolidated snowpack
December 24th - January 3rd: Amazingly light pow almost non-stop, periods of high wind, steady temps between 15 - 28F
January 4th: Clear and cold, some wind,

You have the glop, then you have the light stuff. Keep an eye on that layer for good bonding. That stuff could run. Also, that cold, clear calm stuff could mean some trouble as well as a lot of the moisture content in the snow will be lost to the atmosphere, which means less bonding (in short).

Take a class if you haven't.

NWAC is your friend.

http://www.seawfo.noaa.gov/products/SABOR

Certainly you shouldn't rely soley on NWAC, but when your gut instinct lines up with what they are thinking, well...

Quote:

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Originally posted by Platinum Pete
January 4th: Clear and cold, some wind, occasion sun breaks, mostly just overcast

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Surface Hoar!

Quote:

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Originally posted by joshbu
NWAC is your friend.

http://www.seawfo.noaa.gov/products/SABOR

Certainly you shouldn't rely soley on NWAC, but when your gut instinct lines up with what they are thinking, well...

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The NWAC mountain weather forecast is pretty pointed, too:

"A north flow aloft which brought a very cold air mass to the area
has changed to a much warmer southwest flow. This is resulting in
dramatic and locally dangerous weather in the Northwest,
including a high to possible extreme avalanche danger in the
Olympics and Cascades"

I hadn't thought of the clear day leeching out consolidating moisture or making surface hoar. Thanks for the perspectives. More?
I always check NWAC before I go, but their forecasts are so broad. I mean, the weather systems hitting the Olympics are very different from what happens on Hood.

I'm planning on taking an avy class this winter. I heard that the Canadian Level 1 course covers more than US Level 1, so I may head North. My only concern with that plan is that a taking a course in the PNW, where I ski and climb most, would give me better localized assesment tools. Conversely, learning the more complex Canadian Rockies avy skills might make me more than capable of handling the comparatively simple Cascade snowpack. Any thoughts?

Quote:

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Originally posted by Platinum Pete
I hadn't thought of the clear day leeching out consolidating moisture or making surface hoar. Thanks for the perspectives. More?
I always check NWAC before I go, but their forecasts are so broad. I mean, the weather systems hitting the Olympics are very different from what happens on Hood.

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Well, for starters, NWAC does not issue a single forecast that covers everything from the olympics to hood. The forecast I linked to includes a zone forecast for "MT HOOD AREA...SOUTH WASHINGTON CASCADES NEAR AND WEST OF THE
CREST..."

That's still fairly broad, hence you still need to dig your pit and use your best judgement.

However, when the forecast reads: "High to extreme avalanche danger on Wednesday below 7000 feet." I tend to just let it go.

We have a region-specific avy forecast that I check religiously, but even then, it is what it is. Sometimes when avy danger is "high," I'll go out and do a low angle tour just to see what's up. Often it is, indeed, high on certain aspects but bomber on the other side of the ridge or in sunnier spots on that same aspect. So it depends. You're better off knowing for yourself by getting out regularly and following weather, snowfall, etc. The same more often applies to when the danger is "low"--it's most certainly not low all over!

Platinum--I'd recommend taking a course somewhere with variable snowpack. The rockies from CO up to BC are about as good as it gets for this. This way you can see the different layers interacting independently instead of globbed together, and you can also ski some pow while you're at it. Just my humble opinion.

Quote:

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Originally posted by Buzzworthy
[hijack] What do you think the chances are of my wife landing tonight aroung 10pm in Portland with the weather being how it is there?? Apparently they cancelled some flights yesterday. [/end hijack]

Internship interview, I hope she makes it.

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If your wife makes it, will you be moving here, Buzz?

Check Avalanche.org and click on your region

The easiest way to tell is to check that site, read some info on digging pits, go out and dig one! Make sure you have your equipment, th emost important one being your brain, know how to use it and be safe.

There are a lot of factors involved, snowpack, depth of snowpack, layers, winds, new snowfall, temps, aspects and the like.

Your question about slides affecting future slides...more slides can easily follow. Because a slide has released means that there was a weak layer existing. Pending on what the weather has done to that layer, cold temps for instance...can weaken the thin layer even more making the chance for a slide to rip all the way to the ground. If temps were warm, a storm came in warm, then bonding will be significantly better than if it has been cold. You have to watch out for depth hoar! Its a weak layer that with any loading can possibly collapse and collapse big!

Past slides can act like glass..meaning anything on top can go with little impact or pressure.....

Lots of info man, get the book by Bruce Tremper, I think its called Surviving an Avalanche and learn.