Snow observations, Mt. Hood northside

[prussik1]

Went on a northside tour today, up through Cooper Spur ski resort, to Polallie Ridge following the ridge to Tilly Jane Trail Junction, to Tilly Jane A Frame, then out towards Cloud Cap Inn, taking snowpack observations on a southeast aspect. Then, meeting a friend on the trail, skiied the pink tape route that parallels the Tilly Jane trail down to the gate. Snowpack observations:

135cm Column Test at 5720' on SE aspect with a 33 degree slope at 14:20. Air temp was -1C, sky partly cloudy, winds calm. No blowing snow. Surface temperature was -1.5C, temperature at 20 cm down was -03C, boot penetration was 40cm.

Layers, resistance and temperatures:

0 (surface) fist, -1.5C

17cm down from surface: fist, -4C

65cm down from surface: 4finger, -3C

135cm down from surface: pencil, -2.5C

 

The concern is to watch for the temperature gradient between the 0 layer and 17cm layer. Any temperature change of over 2C in 10cm means that the layers are not bonding well. When snow is deposited on top of these types of layers, it can lead to a higher avalanche risk.

Test Profile:

No propagation of any layers.

Fractures at CTM 19@ 30 cm

CTH 23@ 130cm

Both fractures resulted in Q3 shears.

Christopher

 

Edited March 7, 2011 by prussik1

[powderhound]

did you see the black spider? conditions

[prussik1]

Sorry, no beta on the route.

[powderhound]

you have no beta? OR you are not going to give me any beta? you walked/skied right under it:)

[corvallisclimb]

heres a pic of recent conditions Bryan. I just got back, had to turn around do to visability. But I got a pic of the spider!

 

[powderhound]

heres a pic of recent conditions Bryan. I just got back, had to turn around do to visability. But I got a pic of the spider!

 

 

Nice, thanks for the laugh Mr. Adams. I appreciate you helping put a smile on my face while sitting in my little cube. Almost done with busy season and I can soon start climbing outside on the weekends again!

 

p.s. we need to have another night of long islands

 

[corvallisclimb]

:tup: Jake and I will be out at Smith/Camp Sherman this weekend if you get bored!

[Maine-iac]

http://www.skihood.com/Community-and-News/Meadows-Blog/Posts/2011/03/%7E/media/A9091F53CCAB422EB0E7B81263958AAA.jpg

 

 

[hippos_are_evil]

After seeing this bigass avy with a crown of over 6 feet, I was wanting to know how to determine it is safe again.

 

I would imagine most avy pits don't go down to the layer we saw this avalanche sheer at. Is it a quasi-guessing game at how many melt/freeze cycles it takes to consolidate the snow all the way down?

[sean_beanntan]

Hmm I would also be interested in how some folks view this, my take on your question.

 

The slide was not a natural trigger so that the weak layer may have consolidated without external trigger. If the layer is failing on a large facet layer, it will take a long time to consolidate. The main process going on is changes to the thermal Gradient inside the pack. Warm overnight temps for the next week will eventually strenghten that deeper layer rather then a freeze cycle (imo)

 

http://avalancheinfo.net/fixed/weather/glossaries/advanced/advdefs/metamorphism.html

[prussik1]

sean,

I am not fully understanding what you mean by the slide was not a natural trigger, and that the weak layer may have consolidated without external trigger. A faceting layer IS the weak layer that could potentially fail. The thermal gradient is an indication of the inhibition or non-inhibition of airflow within the snowpack, telling of what is going on at the molecular level of the crystals.

This slide's crown was an average of 5-6 feet, about the depth of a test profile if one is curious about those layers. Remember, a test profile only confirms what you already know when you leave your house. telemetry data, snowpack info, and weather data give information as to what is going on in the snowpack already. This is the same layer that was failing at ctm 12 and 18 two weeks ago with Q1 shear. Now, with wind loading and more snowfall, it propagated during or immediately following a storm cycle which we see regularly in our maritime climate. With this layer being suspect, future test profiles will want to include this layer as well to see what is going on with it.

cheers, all, and thanks for keeping this avy-based thread going!

[Water]

it was not a natural trigger: artillery fire from avy control at meadows is responsible, i thought. "It was determined that the avalanche was triggered during our Artillery mission on the morning of the 10th just after 6:00 am." as per the meadows blog.

 

total novice with avy analyzing, I'm wondering if at any point, does snowpack mass above weak layer help to consolidate/compress it/bond the layers better? just wondering if it plays a role. My gut tells me just as having a weak layer 6 inches down is going to respond diff. to environ than a weak layer 60 inches down, not sure if it is temperature alone?

 

thanks

[sean_beanntan]

My information is that it was a ski patrol trigger and that it failed on a melt freeze crust and then on a rain crust and not a facet layer.

 

... as per Meadows " The initial slab was one cohesive unit which failed from under a more recent melt-freeze crust probably from the middle of February. As the slab moved down through Super Bowl it scoured down revealing the MLK rain crust."

 

Water, on your question, remember that the ground surface is around 32F, so that in the PNW, snow buried deep tends to be near that temp in winter. If there is a low temp gradient then rounding and consolidation will happen even deep down in the pack.

 

Also remember that snow is a good insulator but ice is a good conductor of heat....just to mess with your head

 

 

Edited March 17, 2011 by sean_beanntan

[Teh Phuzzy]

soo... any new info on the north side?

 

Probably not good, but we can always hope...