From NWAC - This is worth noting

I have observed those on the eastern slopes, just over the crest at Crystal.
I was baffled by the observations. My fears on more open slopes was less of the underlying glop, even though my awareness was heightened of a possible slop-a-lanche. I was concerned that the upper crust melt freeze layer slope above me would fracture into plate glass shards and we would be turned into joliet carrots since it was hovering over the glop. Envision a whole slope above you that is a 1.5" melt freeze layer suspended over glop-not a good safe feeling.

That's a pretty bizarre observation, Joe. Must have been kind of a one of.

That's a pretty bizarre observation, Joe. Must have been kind of a one of.

I wish I took pictures of that.
We had over 120 years of collective BC experience in our group, but never had anyone seen this weird widespread condition. It was strange as we all scratched our heads and got out of the basin carefully and quickly. One for the ages maybe?

Mark Moore of NWAC still thinks it is a bit of a ticking time bomb for more large releases because the saturated snow will have a difficult time refreezing this late in the year and it will take time for water to drain out of the snowpack to the point where a smaller avalanche would not risk releasing a whole bunch of snow (entrainment or slab).

Although the vis has been poor (foggy with snow today) some of the large avalanches that have been seen include (3) explosive released 5-10' slabs in Bearpit at Crystal today, a very large natural (larger than a couple of weeks ago) into Heather Canyon on Mt. Hood on 3/30, an estimated 10' natural slab on Chickamin Ridge, and a somewhat smaller slab on Alta Mountain that went to the ground, besides the Stevens avalanche, which is historically pretty large for that path.

NWAC www.nwac.us has some good photos including some impressive ones from the Shuksan Arm slide of 3/14 by going to their home page and then clicking on the "Resources" tab at the top of the page, you'll then see "Avalanche Photos". Here is the direct link: www.nwac.us/photos/view/avalanches/current/

Here's a link to Crystal blog showing some big slides on 4/2/11.

kimkircher.com/2011/04/02/climax-avalanc...-causing-big-slides/

I wanted to add a couple of additional bits of info as this thread to me started out as an archive of this unusual winter - it obviously morphed into quite a bit more. From the www.avalanchenw site for around 3/31

Pertinent and interesting information posted on Snowest Forum today about avalanching by user "Lake Cle Elum" www.snowestonline.com/forum/showthread.php?t=265673 Blewett - Avalanches and Down Trees.... A heads up to anyone heading up out of the Blewett Sno-Park: 5 of rode there today. Big tree across the road just 2 miles up. Clawed our way up the bank and got around. Small Avalanche at the rock slide. It stopped at the road and blocked most of it, but room to get around with a little shoveling..... Due to a dead machine being towed out, we crossed the rock slide 2 more times B4 noon and one more small avy. AND THEN: At the end of a long day, tried to cross coming down, but the big one hit after we had been across 3 times today.....Slid all the way from top to bottom, taking out many trees just below the road. Would estimate 200 yards wide. As grooming is over, it will be there awhile. We didn't want to push our luck and decided to ride the long way around and stay on the roads. 3 to 4 miles of bare dirt down near Liberty......Many other small trees across the road.......

This should happen on the east side quite a bit with warming this spring.

I wanted to add this one, too:

A large class 3.5 to 4 avalanche released naturally on a NW aspect on 4/6 between about 0300 and 0600 based on new snow amounts covering the debris. At 7000' the crown is about 150 yards wide, and for much of it's width about 12' high. It apparently released when a not that large chunk of a cornice fell onto a small section of the starting zone where the angle was in the range of 42-44 degrees. The rest of the starting zone angle was 35-38 degrees ranging down to the low 30's on it's right edge. The slab length was about 100 yards. The avalanche then encountered a lower angle section of slope where it left numerous large blocks, leaving the upper track looking like a wrecking yard for white Land Rovers, Navigators and with the occasional Hummer thrown in for good measure. The slide continued down until it reached a gully at roughly 5800'. At this point it stepped down into wet snow (a 2-3' crown was visible on the westerly side of a moraine) and entrained a large volume of snow. The avalanche deposition which consists of large rounded balls looks to be 20'-40' deep and continued down to 3600' (and beyond). Only about 6" of dry snow covers the debris. The bridge to Kulshan Cabin undoubtedly followed the debris downslope. The debris completely obliterated the line of the creek and in places extends into the forest a short distance.

Although only a fraction of the size of the 1990 slide, it is nonetheless impressive.

Another perhaps 5' deep slab about 100 yards wide released around the same time on a SW aspect near 7000' just west of Chowder Ridge. The avalanche debris doesn't appear to be heavily covered and a forested area has become a ski run in the run-out zone.

These slides (especially the first) indicate that the deep weakness is still susceptible to failure particularly when recently loaded (or when warm) with a sufficient trigger.

Yesterday I had the opportunity to fly over the Cascade range in a friend's Cessna with the express purpose of doing an avalanche inventory.

I spotted about 30 mega slides with large enough dimensions and good enough detail to photograph. Many of these slides, which are of many different ages, have simply disappeared because of the amount of recent snowfall and wind (eg. the Shuksan Arm 15' crown was not visible from the air). But, notably, they are coming out with each loading/warming event. Thus far there is a pattern to these slides; Most are on steep slopes in the 7000' to 8000' range on N to NE aspects (but not all). They are most common near the crest in heavier snowfall areas because of loading and cornice collapse that accompanies heavy snowfall and wind. Many have been triggered by cornice failure, some failed at prominent convexities. There are as of yet few failures of large dimensions east of the crest. As a matter of fact after flying down Railroad Creek, Devore Creek to Lake Chelan and then up Bridge Creek to Cascade Pass I gave up on east side avalanches and focused on the more prevalent slides nearer the crest. Nevertheless, there are large recent (4/6) slides on Snowgrass Mountain, just north of Big Chiwaukum, and another that was visible from about 5 miles on The Cradle.

My personal guess is that the fact that they are not releasing except on steep slopes reflects the fact that there is a strong layer that is bridging the deep weakness, and is not at all indicative that we won’t see failures on more moderate slopes with heavy loading; or more likely, with spring time warming. I also think that the east side avalanches will also be major but lack of loading and a cold snowpack north of US2 has limited them so far.

There are also scads of small but 2 meter deep slabs that came out in the warm, wet weather of late March, most on convexities. So the weak layer exists at all relevant elevations and is a sleeping giant.

The largest slide on 4/6 on Mt. Baker was ½ mile wide with a 10-20’ crown, started at 7500’ on a west aspect and ran three miles to the 2500’ level of Wallace Creek west of the Black Buttes.  Another on Mt. Torment started near the summit and took out a strip of timber ¼ mile wide by 2000 vft  to the Cascade River. Although this latter avalanche is really no longer visble because it was a powder avalanche that probably released around mid-March, it has left just a handful of mature trees that look like tall kids with crewcuts – no branches for the first 75’ or so and an otherwise completely denuded slope down Gilbert Creek and along the divide west of Morningstar Creek. These and another large avalanche on the north edge of South Mowich Glacier from 7200’ (appears to have been a full depth climax avalanche) are solid Class 5 avalanches.

Other 4/6 avalanches of note were the two large slabs in the Chiwaukums, the large one on Baker, another below Seward Peak, the previously mentioned Grouse Creek slide and a big one on the west side of Eldorado. The event that presaged these slides was about 40” of new snow loading with wind.

Because these avalanches responded to loading so effectively, I have to believe spring warming will see many avalanches that fill entire valleys in places one would not expect avalanches.