By guest blogger Summer Derrey

Every year, our avalanche and maintenance crews work to clear the snow from Chinook Pass to reopen this section of State Route 410 for summer travel. It takes the work of crews from both sides of the state. Recently, I traversed the 5,430-foot pass to see for myself how the reopening effort works as crews clear Chinook from the east side.

Step 1. Safety first. Strap on an avalanche beacon, look for signs of potential avalanches like snowballs forming at the top of slopes, listen for the shhhh shhhh sound of snow sliding down the mountain and watch your step.

Step 2. Find the road. This year, it’s buried under 20 feet of snow.





Avalanche specialists knock down loose snow above the highway
Avalanche specialists clear the steep slopes of snow using several methods. Crews ascend to the ridgeline on skis, pushing into the snow intentionally triggering avalanches. They also pack in explosives and set charges. Occasionally, helicopters drop explosives in hard-to-reach areas.

Maintenance crews clear snow on the highway snow
Maintenance crews keep a safe distance behind the avalanche specialists while clearing the highway, using two bulldozers and two snow blowers. The pioneer dozer, led by team veteran Tom Martinson, climbs to the top of the snow pile and methodically carves a path 20 feet above the highway. Using a process called side-casting, Tom rocks the dozer perpendicular along the hill side pushing the snow off the cliffs with the dozer’s blade.

“There is a little less snow this year,” Tom said. “It’s been a piece of cake.”

Tom may have a sweet tooth, but the danger is always bitter sweet. Tom has to keep the snow and his rig level; otherwise, he could slide off the cliff. Meanwhile, Nick Zirkle is in the second dozer and uses a process called spading. He loosens the hard snow and ice with the dozer’s blade, creating a series of heaping piles for the blower to expel off the cliff. Doug Sutton is the veteran snow blower. His blower feeds the snow into the box, launching powder 40 feet in the air then whirling down the steep cliffs. John Rath is in the second blower and he’s like the dish washer, clearing every speck of snow off the highway.

Clearing snow is a slow and methodical process. It’s sort of like peeling layers off an onion one by one. By early May, after weeks of clearing, eastside avalanche crews meet up with the west side Greenwater crew near the top of Chinook Pass.

But the pass is not open yet.

Maintenance crews need to reinstall all the highway signs. The signs are removed each year; otherwise, avalanches would rip the poles out of the ground, pushing the signs to the valley bottom. Crews also monitor weather and avalanche danger. The snow build-up along the rock walls will loosen and topple onto the highway when conditions warm up.

Crews prefer to reopen Chinook once conditions are stable enough to keep it open. That way, drivers don’t get stuck on one side or the other and have to drive all the way around to White Pass on US 12.

Finally, crews unlock the gate and swing it open for six months of recreational travel. When will it open this year? Crews are on schedule to reopen a couple days before Memorial Day weekend, although that could change, depending on weather conditions and safety.

Chinook by-the-numbers
On average, crews clear 5.5 miles east of Chinook Pass using two bulldozers and two snow blowers. Four to six avalanche specialists knock down snow using 1,600 pounds of explosives in a four to six week period. Crews clear a minimum of 602,300 cubic yards of snow from the highway – not including the snow the avalanche specialists knock down from the mountain. It takes approximately 1,280 crew hours to reopen Chinook Pass each year.

by guest blogger John Stimberis

As an Avalanche Forecaster I work in a snowy environment where I am able to explore a variety of questions related to avalanches, weather, and snow. Outside of work my colleague Charles Rubin (CWU Geosciences) and I explore some of these questions and occasionally find answers. We had our paper Glide avalanche response to an extreme rain-on-snow event, Snoqualmie Pass, WA published in the Journal of Glaciology this month. I’m sure you’re asking “What is an extreme rain-on-snow event “, “what is a glide avalanche response?”, or “when will summer actually begin?” Well, before I answer these questions let me provide a little background information. Dr. Rubin, he prefers Charlie, and I have been working together on avalanche related issues for the past eight years. Much of this work is done in my spare time, kind of like a hobby. OK, full disclosure- I am a snow geek, nobody does research in their spare time as a hobby unless they are a complete geek.

Anyway, now that we’ve cleared that up let’s get back to the research. Charlie and I have been studying a glide avalanche slope near Snoqualmie Pass. Glide avalanches occur when the entire snowpack slides as a cohesive mass, right to the ground. These events are rare in their distribution and are difficult to predict when they will release. During our research we’ve managed to record a few events, provide data for some of Charlie’s graduate students, and stay interested enough to continue with the work.

During January of 2009 a large storm was forecasted to affect Washington State. This was going to be one of those Pineapple Express storms with lots of rain and flooding due to high snow levels. Charlie and I figured the rain would trigger a glide avalanche due to the warming and water flowing through the snow pack. We were ready to record the event using the various sensors that were in place. I was also ready for the normal snow avalanches that might affect I-90. Rain often triggers avalanches within minutes of the first rainfall. Our avalanche crews performed a full round of avalanche control prior to the arrival of the rain to keep any rain triggered slides to a minimum.

Our expectations were met when the rain arrived and we observed only small slides or sluffs that didn’t reach the highway due to our preemptive avalanche work. The rain fell throughout the day and into the night at a heavy rate, sometimes as much as .45” an hour. It looked like everything was going to be fine. The snowpack was absorbing most of the rain probably because the snow had been so cold and dry up through early January. Here’s where it gets tricky, don’t let down your guard. Just when it all seemed ok, it wasn’t. A large flow of water, slush, ice, rocks, and trees hit the highway in the area of a stream/avalanche path. Our Maintenance crews quickly cleaned up the area, but new problems were popping up everywhere. The water had finally made its way through the snow and the flood was on. The highway turned to a river. Interestingly, the glide avalanche slope wasn’t doing much.

By the following day we assumed the worst was over. Water was flowing freely through the snowpack and lowland flooding was now the big concern.

Massive landslide at Hyak in 2009

Wrong again as a massive landslide consisting of rocks, mud, woody debris, and snow let loose at the Hyak Ski Area. This slide took out a chairlift and a couple of houses. Still no glide avalanche though. The rain began to let up and by mid afternoon we had almost given up on the glide avalanche when it finally occurred. Even though the rain had affected the snow surface (usual onset of snow avalanches), then penetrated the snow to lubricate the base of the snowpack (typical trigger for glide avalanches) we didn’t see a glide avalanche. When the rain begins to let up we generally assume the snow is stabilizing and we won’t see any more avalanches, but we did.

Charlie and I assume it took so long to happen because the snow pack prior to the rain was cold and dry. It took some time for the snow to settle and become a large cohesive mass, something we feel is necessary for glide avalanching to happen. Once the snow began to settle we saw the glide rates increase. It’s worth noting that normal avalanches happen quite quickly, while glide avalanches are often slow to develop. Our snow study plot on Snoqualmie Pass recorded a 3 foot decrease in the snow pack during the rain event. People often assume the snow is melted by the rain during these storms, but it takes a lot of energy (heat) to do that and there generally isn’t that much in a rain storm. What happens is most of the snow compacts and settles, which is good for stabilizing avalanche conditions, but not for the glide avalanche. I’m glad we don’t have many of these glide avalanches to deal with.

After the storm Charlie and I assessed our data and put together a paper describing the event. We presented the results at the International Snow Science Workshop in Davos, Switzerland. It was quite an honor to go there and speak to snow geeks from all over the world. We were encouraged to expand our report and submit it for publication in the Journal of Glaciology, and after revisions and peer reviews we were accepted and published. We plan to continue our research during the coming winters, and who knows maybe someday I’ll find the time and money to get a master’s degree of my own.

Hopefully this article sums up the paper, but just in case you want to read the full account (pdf). At least you now know what a rain-on-snow event can do and what a glide avalanche is. As for the third question, summer technically began on June 21, but we here in the Pacific Northwest know better. According to some forecasters summer really begins on July 12. Whenever it arrives remember to enjoy a little, it will be gone before you know it.

By guest blogger Jeff Adamson

Hi all,
You probably know the North Cascades is closed.  It snowed all night and when Liberty Bell #3 filled and dumped across the road, the plow truck driver who had been working all night was told to get out of there, and close the gate on his way.  The forecast says we've got another foot or more coming between now and tomorrow, so it's not safe for our crews to be working under unstable avalanche chutes anymore than it's safe for you to be driving under them.  I'm rooting around through the record books and haven't yet found an avalanche closure this late - but I'll keep looking.  I just got off the phone with Mike Stanford, our Avalanche Control Chief.  He will be up there tomorrow doing the assessment of avalanche danger.  He's taking the howitzer along so if some avalanche control blasting can get us open again quickly, he'll be able to do it.  It really depends on what happens to the Cutthroat Ridge chutes - if they're full and unstable - we might just have to wait a day or two for the temperature increase that's coming later in the week to cause them to empty. (Due to the topography, you can't shoot Cutthroat starting zones from the highway with the 105mm.) 
By the way - depending on how much of the forecast' 6 to 10 inches of snow hits Stevens - he may have to deal with some avalanche issues before he leaves his office at Berne Camp (that's our maintenance facility 8 miles east of Stevens Summit.)
Sorry, no pictures (no one better be up there to take any!)  We're manning the gates just in case any back country recreationist we weren't able to contact show up wanting to go home.
Here's what the Highway Alert that went out this morning:
WSDOT Alert
DATE/TIME: May 3, 2010, 9:30 a.m.
DESCRIPTION: SR 20, the North Cascades Pass, is closed from milepost 134 to milepost 170.
LOCATION: SR 20 at milepost 170 North Cascades Pass
START: May 3, 2010, 9:30 a.m.
Est. END: Unknown
OTHER: Due to avalanche danger, high winds, and incoming snow, the North Cascades Pass is closed until further notice.
CONTACT: NCTMC (509) 667-2802

Here's the forecast:
Snow over Washington and Rainy passes will continue through the day today with heavy snow showers and squalls expected during the midday and afternoon hours.  There is the potential for significant snow accumulations over both Washington and Rainy passes (upwards of 12”+), with slush potential as low down the hill as Diablo on Mon afternoon and evening.  Most of the snow concerns remain over the passes, with little cold-moisture making it much further E than Early Winters.  Snow levels may drop as low as 1,500 feet Monday night into Tuesday morning with more snow expected, mainly West of the passes.

Happy May!

(This was sent out via the North Cascades email distribution list this morning. Sign up to get this and much more information sent directly to your inbox. )

by guest blogger Jeff Adamson

The question comes up every time we have a mild “El Nino” winter in the Cascades, but the answer is the same. Sending our Avalanche and Maintenance crews to do a reopening assessment any earlier than late February/early March, wouldn’t work since there's still too much winter ahead. They need to be able to make any objective determinations about when to begin the reopening process. That is, setting a firm start date, figuring out how much and what kind of equipment will be needed (for example, we have to put the caterpillar work out for competitive bids) and get our internal crews and equipment lined up. North Central Region has a 3 man avalanche control team, Avalanche personnel are required to be on site while the crews are clearing the highway through the avalanche zones. Last year, for example, work on the North Cascades was delayed a couple of times when the Avalanche team had to go back to Stevens Pass in order to keep it open. The Kodiak snow blowers we use are from the three assigned to Stevens pass and can’t be released to NCH until they're not needed there. That means the clearing work usually begins with only one blower and more are “sent north” as they’re “available”.

Our Avalanche forecasters have lots of historical data and "know snow" and have done a pretty good job over the years picking a start date that worked, but doing the assessment any earlier could be risky and really unnecessary.

While we're always being urged to open the highway as soon as possible (preferably by the opening weekend of fishing season), we also hear from some winter recreation businesses that ask us not to open before Easter because when we do, it costs them business! Apparently, we’ll never please everyone.

Please remember that on the North Cascades, we do not do “active” avalanche control like we do on Stevens and Snoqualmie. Washington (and also Chinook) pass are federally designated Scenic Highways that are closed during winter. We really can't knowingly put our crews or drivers at risk by opening a highway before it can really stay open. In 2005, we had the earliest SR 20 opening ever on March 10. By opening that early, and then having a huge storm hit, refilling avalanche chutes, closing the road again for 10 days, we had to bring back the crews, equipment, etc. and repeat much of the reopening work. That "extra" clearing effort might not be considered to have been the best use of our gas taxes.

By the way, checking that last "El Nino" year for Stevens Pass one finds we had almost no avalanche control and low snow accumulations until March when we got hammered with almost 200" of snow. By way of comparison - there's less than 90 inches on the ground now and the total accumulation for this season, so far, is less than 250 inches. Last year’s season total was about average at 434 inches.

We have received a lot of curious emails lately asking us why we close the mountain passes when there is risk of avalanche danger. I could tell you, but I thinks that these photos will tell the story better. When you see what an avalanche looks like and consider the danger of being buried by one, you can see why we take the closing of the passes very seriously.

Stevens Pass - February 2008 - Tunnel Creek


Snoqualmie Pass - January 31, 2008 - Cars stuck in both sides of avalanche
Did you know that there are at least 40 avalanche chutes on Snoqualmie pass alone!


SR 20 - January 2008 - Newhalem - Not just snow comes down in an avalanche, sometimes rocks do too.


SR 20 - January 2008 - Aerial View - Newhalem slide


Typical Avalanche at Snoqualmie Pass East snowshed - an avalanche of this size can cause the pass to be closed for two hours.


As you can see there is considerable risk to any vehicle that tries to cross the mountains when these dangerous conditions exist. We appreciate your patience while we take the appropriate time to make sure the highway is safe for travel.