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zephyr
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zephyr
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PostWed Apr 11, 2018 1:19 pm 
Token Civilian wrote:
Link to reports page. https://www.nwac.us/accidents/accident-reports/
Thanks Token Civilian for posting that link to the accidents page. From there I got the direct link to the report, a PDF. This is very good reading with several photos and a Google Earth shot with markings to show the location of the avalanche. I also want to quote from this report. From Jeremy Allyn, a NWAC Observer--quote: The fact that this particular slope has a history of producing large avalanches that have also killed people is significant. The slopes on, above, and adjacent to the summer trail leading to Snow Lake Divide are prime avalanche terrain. The same can be said for the other popular route to the Snow Lake Divide via terrain NW of Source Lake. Both routes involve significant overhead hazard and high levels of exposure and commitment. There is no avalanche “safe” route to the Snow Lake Divide. Avalanche slope history is important and repeat offenders like the slope that produced the fatal avalanche in this report should be taken very seriously relative to their history. Equally important is the history of recreational use in the Alpental Valley where this avalanche occurred. While awareness and use patterns have improved in recent years, the continued, almost daily use of the Snow Lake summer trail during the winter months (especially during periods of elevated avalanche danger) continues to be alarming. Whoa... I didn't realize it was that bad--"almost daily use of the Snow Lake summer trail..." ~z

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iron
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PostWed Apr 11, 2018 1:35 pm 
very sad to read that report. obviously those kids had a passion for it; they were there the day before. lack of experience or judgment put them back in harms' way. they didn't know any better, which is the hard part. avi awareness and training helps, but judgment comes with experience. even in my own groups (when i used to hike), i am always the most cautious one when it comes to avi and cornice concerns, so i can definitely see why they wanted to push on --- i have seen it and experienced it. just a sad outcome from a bad combination of elements.

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joker
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PostThu Apr 12, 2018 12:16 am 
zephyr wrote:
Whoa... I didn't realize it was that bad--"almost daily use of the Snow Lake summer trail..." ~z
I've seen a well pounded track starting up where the summer trail starts in all sorts of conditions over the last few winters, when heading up to ski at Alpental. Often hikers setting out or returning too. It's been a bit distressing given how high the hazard has been due to fresh snow dumps several of those times.

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thunderhead
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PostTue Apr 17, 2018 4:53 pm 
Lots of new snow out there. Big slide at alpental... all the way to the base it looks like.

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cascadeclimber
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PostWed Apr 18, 2018 7:05 am 
All this late season heavy, wet snow is going to make for a dangerous spring skiing/climbing season when the sun and warmer weather finally appear. Our typically well-consolidated spring/early-summer snowpack is not likely to form up this year.

If not now, when?
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gb
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PostWed Apr 18, 2018 8:31 am 
The avalanche at Alpental was a climax glide avalanche off a rock slab just south of Snake Dance that ran nearly to the upper parking lot according to a friend who lives up there and sent me images. Last weekend control work filled all of International with slide debris. Apparently the ski area is pretty concerned about large slides. The s*&^ will really hit the fan this (next) week as freezing levels ramp up late Monday after a cool Saturday to 6500 to 7000' and then are forecast to around 9000-10,000' Tuesday and even higher by later Wednesday into Thursday if the GFS model pans out. With all the recent snow and the low snow remaining from February's cold weather, avalanches could be expected to run all the way to valley bottoms this (next) week. Large avalanches of the recent snow could also take out as wet slabs deeper slides involving all of the snowpack down to the February 8th week layer. Not a great week to be exposed. It wouldn't be surprising for the NWAC to put out a special statement in the near future although they often do so just for weekends. This for the week of April 23rd but even today and tomorrow get warm enough for more than a few wet slides. This should be the first big spring avalanche cycle and will be repeated as temperatures step up in the early to mid-spring.

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thunderhead
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PostWed Apr 18, 2018 10:55 am 
Theres some pics on their twitter account https://twitter.com/SummitSnow411

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gb
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PostSun Apr 22, 2018 6:51 am 
a major spring avalanche cycle is still on track for this coming week as relatively low freezing levels recently rise to 7000' or higher Monday and continue to rise during the week to as high as 12,000' Thursday. Lower elevation south slopes have already seen some consolidation but probably much less so at higher elevations and on other aspects. Wet snow avalanches and cornice triggers will take out some very large slabs, including in some cases all the way down to the February 8th layer which must be some ten feet down above 5000' west of the Cascades. East slope locations should also have a major cycle.

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thunderhead
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PostSun Apr 22, 2018 7:19 pm 
Agreed. The mountains are gonna be bringing out the big guns during warm hours this week.

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gb
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PostTue Apr 24, 2018 7:26 am 
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gb
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PostThu Apr 26, 2018 5:47 pm 
Mt. Baker hit 66F at 5000' today and Paradise reached 75F which has to be one of the warmest April days of all-time. The snow might just be a little sloppy....

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puzzlr
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PostThu Apr 26, 2018 10:14 pm 
I meet an overnight hiker who tried to climb Big Snow. I think he camped at lower hardscrabble lake and saw six sizeable avalanches yesterday and more this morning. He wisely turned around and hiked out.

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RichP
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PostFri Apr 27, 2018 4:54 am 
Flying into Seattle yesterday I could clearly see some big slides on the higher peaks even from 10,000 ft.

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ale_capone
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PostSat Apr 28, 2018 6:04 am 
Was 08/09 a year when we had a pwl? I think? In late May we where on route to Eldorado, and got some crazy sounding whoomphing. Warm and sunny day, mid afternoon. just above the boulder field, and a couple more in the flatter areas after the notch. We would get a large area to suddenly collapse. It would whoomph, and then be followed by what sounded like a million rain sticks. Is this a common thing? A name for it? I don't recall ever hearing about it anywhere.

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gb
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PostSat Apr 28, 2018 8:25 am 
ale_capone wrote:
Was 08/09 a year when we had a pwl? I think? In late May we where on route to Eldorado, and got some crazy sounding whoomphing. Warm and sunny day, mid afternoon. just above the boulder field, and a couple more in the flatter areas after the notch. We would get a large area to suddenly collapse. It would whoomph, and then be followed by what sounded like a million rain sticks. Is this a common thing? A name for it? I don't recall ever hearing about it anywhere.
At that time of year it is not really very likely that this is a result of what in winter would be called a persistent weak layer in which depth hoar, faceted grains usually near a crust, or buried surface hoar are the likely culprits. What you are describing is what I personally call a thumper crust. Occasionally one sees a phenomena in mid or later spring where a large section of weakened crust suddenly collapses. My take on this is that there has been a supportive crust overlying yet unsettled relatively lower density recent snow. This underlying snow is damp and not particularly well bonded internally so that beneath the stiff crust which has resisted settlement due to it's stiffness the layer of damp snow settles naturally somewhat. Then on a day that is warmer than it has been the crust in areas is essentially sitting on air and fails resulting in sometimes wide area collapse. It seems that this crustal failure and the imparting of energy could signal the potential for wet slab release. Whether that could happen or not is likely dependent on how forceful the collapse, how weak and wet the underlying snow is and whether there is a hard bed surface beneath the underlying snow and also whether there is liquid water at the bed surface to create a lubricating layer that might eradicate bonding to the bed surface. But, given the nature of spring weather with cool spells and new snow interspersed with warming that helps to create crustal layers it is likely in spring that there would be a hard crust beneath the weak wet snow that settles and sometimes collapses. And on a warm day in spring meltwater percolation to the bed surface is also likely. But this is all theory. Nonetheless, when I encounter such conditions in spring I am quite concerned. In winter or earlier spring it is more likely that collapse is failure of a persistent weak layer as above.

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