Microbursts, Sneaky and Dangerous

Damage resulting from a microburst near Butte, Montana in 1999
According to Green Gables General Store owner Edith Farrell, who runs
the information center near Granite Falls on the Mountain Loop Highway,
microbursts are common storms in our Washington State mountains.
A number of years ago, wind felled a patch of trees on both sides of the Mountain Loop Highway, near Big Four Mountain. As years went by, their bleaching trunks lay pointing west, as if pushed over by a mighty hand. Each time we passed them, I wondered why so many had fallen simultaneously in one small area. It looked as if a powerful but short-lived wind had blasted through, toppling everything in its path.

As I found out, that’s exactly what happened. In a microburst a bubble of cold air drops rapidly from the clouds and bursts like a water balloon when it hits the ground, sending winds at speeds of up to 100 mph or more racing outward from the center. In dry climates, the storm might be invisible except for the dust kicked up as the winds shoot out from the point of impact. In more humid climates, it may be accompanied by thunder and rain.

Until Edith mentioned microbursts, I had no idea that the trees near Big Four had been destroyed by such a storm. And yet, microbursts are relatively frequent, occurring ten times more frequently than tornadoes.

Any strong winds descending from showers or thunderstorms are called downbursts. A microburst is a downburst covering an area of 2 1/2 miles or less in diameter. If the storm is larger it’s called a macroburst. Microbursts’ small size and short duration make them hard to predict. That’s why I call them sneaky.

You can differentiate a downburst’s damage from that caused by a tornado. In a tornado, winds spiral upward into the storm, leaving a swirling pattern of damage. In a microburst, the wind blasts downward, then outward. The pattern of damage lies in straight lines, which is why they are called straight-line winds.

In 2007, a macroburst with straight-line winds of 120 mph felled long swaths of timber along Highway 101 near Grays Harbor on the Washington coast. We drove through that area the following spring, and saw hundreds of acres littered with trees like toothpicks spilled from their container. This spring, in 2016, a new forest had sprung up. Only the broken stumps of the older forest poked through.

 

 

Broken trunks from the storm of 2007 rise above the new forest.

Microbursts are particularly dangerous for aircraft since the storms’ small size make them difficult for pilots to detect. Wind shear, a radical shift in wind speed and direction that occurs over a very short distance, has been perhaps the biggest cause of weather-related plane crashes.

The following graphic, from the National Oceanic and Atmospheric Administration (NOAA)
illustrates what happens when a pilot unwittingly flies into the wind shear inside a downburst. As the plane encounters the winds rolling outward andupward, the plane is briefly lifted up by increasing airflow over the wings. Then the sudden shift of wind speed and direction slows and drops the plane.
Before the pilot can adequately increase airspeed, the plane collides with the ground.

Our friend Dave Penz, former director of the Kako Retreat Center in western Alaska, had a frightening experience one day on the Center’s airstrip, within a few hundred feet of his own front door. Following the annual retreat for bush village educators, he took off with three teachers aboard. They were barely aloft when a microburst hit them. The plane lifted momentarily as the front of the air current rolled under them, but as they flew into the tail wind, the plane plummeted into the evergreens lining the airstrip. One tree sheared off a wing and the tail. The rest of the plane caught on the next tree and slid to the ground, landing upright on all three wheels. Except for bumps and bruises, no one was hurt.

There have been no downburst-caused commercial plane crashes in the decades since improved weather detection systems have been installed at major airports and on commercial planes. But downbursts, whether micro- or macro-, are sneaky and dangerous. They are nothing to fool with.

photo credit: Trees blown down by a burst 1 via photopin (license)

Taking a Day Trip in Our Own Back Yard–the Mountain Loop Highway

Growing up in the logging community of Verlot, Washington, I loved our occasional family drives around the Mountain Loop Highway. Then, as now, the road connected the North Cascades towns of Granite Falls and Darrington. We lived on the south end near Granite Falls, so the area was almost in our own back yard. Now Hank and I live near the mouth of the Stillaguamish River, near Stanwood. 
When we drive the Mountain Loop, we drive the opposite direction, through Arlington to Darrington, on the north end of the mountain section of the loop. It’s still a peaceful, lovely, and sometimes rough route through rainforest, rugged peaks and valleys, and along the Sauk and South Fork Stillaguamish Rivers.

The country is full of history. As you peer through overhanging branches, up forested slopes, you can feel the shadowy presence of Native American hunters on the trail of elk or mountain goats. In the 1890s, the mining boom at Monte Cristo broke the silence of the forest as wagoners hauled heavy machinery and freight along a puncheon road following the Sauk. That first route was soon replaced by the Monte Cristo railroad, built to carry the ore to the smelter in Everett. Trains ran through our valley along the Stillaguamish to Barlow Pass and four miles beyond, ending among the spectacular peaks that surround the townsite of Monte Cristo.

By the early 1900s, the railroad’s frequent washouts made it economically unfeasible to continue large-scale mining. The work at Monte Cristo slowed to a halt.  Then tourists discovered the area. Train excursions continued for a while, then what had originally been a wagon road through our valley of the South Fork Stillaguamish was pushed through to Monte Cristo. In 1936, a dirt road connecting Barlow Pass with Darrington was begun. In 1941, the Mountain Loop Highway was completed. The whole area became a destination for outdoor recreationists, with hiking trails and campgrounds all along the way.

Snow still closes the route in the winters, and in recent years several bad storms have caused enough damage to keep the road closed in summer too. It’s open now, except for the private four-mile section that leads from Barlow Pass to the old mining town site.

 Work is presently going on to remove arsenic-laden tailings from around the old mine tunnels, so Monte Cristo town site is closed to visitors. In order for trucks to reach the area, a road along the route of the old Sauk wagon road was reopened. Many who love Monte Cristo for its recreational values hope that the public will someday be allowed to use this road.

We recently drove our California daughter and her friend around the part of the Loop that begins in Arlington. We stopped to reflect at the temporary monument to 43 men, women, and children who lost their lives in March, 2014, during the horrific landslide near Oso.

When Hazel Hill broke away, it unleashed tons of mud and debris on the Steelhead Drive community and temporarily dammed the North Fork Stillaguamish. A more permanent memorial is planned someday.

Forty-three cedars stand watch over the site.

Outside Darrington, we also took time to circle through Squire Creek Park, one of the loveliest and least-used parks along the route. Quiet campsites and picnic spots are tucked among large evergreens. The park has a shelter, restrooms, and a grassy area next to the sparkling stream. In the fall, salmon swim past on their way to their birthplaces, where they’ll spawn and then die.

A peaceful scene at Squire Creek.

After a satisfying lunch in Darrington at the recently reopened Bradley’s Diner, we turned south for the first nine miles of the connecting road. They’re paved, and alongside creeks tumble down to join the Sauk. We glimpsed rocky peaks through the trees. Just beyond the White Chuck Mountain overlook with its unobstructed view of the mountain—bottom to top—the paving ended. For the next 13 miles, everything looked about the same as it did when I was a child, except the road was a little wider. It’s still one lane with turnouts, it can still be washboardy and potholed, and people still pull out into cleared spots in the forest to camp.

I think fall is the best time to make the trip. September’s bright blue skies and crisp temperatures redden the vine maples. Yellow aspen leaves sift through the evergreens. Rivers run clear and shallow. We were surprised to find salmon spawning in the high reaches of the Sauk. They were battered from their long trip up the Skagit River and the rock-filled Sauk, but they were determined to complete their purpose.

This salmon was exhausted but determined to make it over the foot high channel to where the female waited, circling above the redd she’d scooped out to receive her eggs.

Counting spawned-out salmon on the bank of the Sauk River

Daughter Kari and her dad. The tree has grown on and around a big chunk of granite that an ice-age glacier probably bulldozed from one of the surrounding mountains.

As we neared the spot where the Sauk hurries down from its beginnings near Monte Cristo, we noticed a gash in the forest.  This was the rough road, closed to the public, that has been built along the route of the old Sauk wagon road. Trucks loaded with mine tailings dump the arsenic-tainted debris into a depository that will be be capped with clean material.
Of all the many places of interest along the Mountain Loop west of Barlow Pass, we had time to stop only at Big Four Mountain before making the hour-and-a-half trek back to our starting place in Stanwood. Snohomish County’s most popular short hiking trail, to the ice caves at the base of the mountain, starts here. It is still closed after a cave collapsed this summer, causing the death of one and injury of others who had ignored warning signs. But we still  enjoyed the view of the mist-shrouded mountain and of the Stellar’s jay that came to beg for a cookie. Our California visitors were in awe of the wild scenery along the way. They agreed. Driving the Mountain Loop Highway makes a perfect day trip.

Kari beside the chimney base, all that remains of the elegant Big Four Lodge that once stood at the foot of Big Four Mountain.
Coffee and lemon bars at Big Four.