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)

Two Men, a Book, and Mt. Pilchuck

Edith and David Capocci, with David’s book, Rambling and Scrambling around the Mountain Loop, courtesy Edith Farrell
Green Gables interior with a customer playing a hand-crafted flute, courtesy Edith Farrell

To the delight of travelers along the Mountain Loop Highway, an almost 80-year old landmark at Verlot has been renovated and reopened after closing last September.

The new owners of the Green Gables general store, Edith and Randy Farrell, offer friendly advice to hundreds of hikers and campers who come to play in Snohomish County’s backyard. They also offer food, coffee, and vacation necessities, as well as an eclectic mix of specialty items. For those wanting to know more about the Mountain Loop area, they carry a variety of new and used books.

Green Gables sits at the base of Mt. Pilchuck, the destination of an estimated 28,000 visitors each year. The store is also only a mile or so from where I lived as a child. Almost every day of my life until I left home for college, I looked up to see Mt. Pilchuck looming to the south. Some of my pleasantest memories are of exploring the mountain’s flanks or climbing its peak.

For six years while I was growing up, two naturalists, Harry W. Higman and Earl J. Larrison, studied the plants and animals that inhabit the forests, bogs, lakes, meadows, rocks and cliffs of the mountain. In 1949, they summarized their findings in an unusual, very  readable work of fiction they called Pilchuck, the Life of a Mountain. I’d never heard of the men or their work until I found a copy for sale in the Farrells’ collection.

From Amazon.com

The story’s main characters are Doc, Merle, and their woodsman friend Frank. Although these naturalists are fictional, their adventures, work, and descriptions of life on the mountain are obviously drawn from the authors’ own experiences. Edmund J. Sawyer contributed beautiful line drawings. Since I’ve been an avid nature observer and a lover of Mt. Pilchuck for many years, I found the time on the mountain with Doc, Merle, and Frank a treat not to be missed.

The mountain, like all mountains, is a living entity whose plants and animals are perfectly adapted to their own niches in the ecosystem.  I loved the historical and geological bits sprinkled in, although some of the latter are a little outdated now. The authors give marvelous descriptions of the incredible views, the quickly-changing weather, and days and nights spent at the lookout station on Pilchuck’s summit.

Today’s hikers have easy access to the mountain from the Interstate 5 corridor. They can drive to the 3,150 foot level, leaving only 2,200 feet of altitude to gain in about three miles of hiking. But when Higman and Larrison worked on Pilchuck in the 1940s, the trail began at the Stillaguamish River and climbed upward for five miles, much of it through timber. A trailside cabin had been built at timberline for a man who lived there during fire seasons. He made trips to the summit to watch for fires. In good weather, he found it easier to stay in a tent at the top.

The Forest Service ran a telephone line to the peak and eventually built the lookout a cabin there, with a cupola atop where he could have an unobstructed view. That lookout station was first built by the U.S. Forest Service in 1920, rebuilt in 1941, and renovated by the Everett Mountaineers in 1977.

While reading about that unknown watchman and his cabin, I remembered my first climb to the summit with a group of high-school friends. We wore old shoes and light jackets and carried our lunches in brown paper bags. As we labored up through the forest, the fog turned to mist and then to drizzle. Noticing lengths of rusted wire paralleling the trail, running through porcelain insulators or just nailed to rotting stumps not far above the ground, we guessed we were looking at an old telephone line. We paused to eat part of our lunch at a level spot where piled stones indicated a low wall. Rotted timbers, sunken in moss, outlined a rectangle. After many decades, I finally know why someone had built a cabin halfway up Mt. Pilchuck.

When Larrison and Higman roamed the mountain, they occasionally shared it with mountain goats, cougars, coyotes, and even a wolf. They studied shrews and six kinds of mice, fish, many kinds of birds, and they even found toads at the very pinnacle of Pilchuck. The larger mammals are scarce now, but marmots and pikas, two rodents of the high places, can still be seen by the hikers who stream to and from the lookout on an average day. Those with skill and know-how can still enjoy wonderfully wild and untouched spots on Pilchuck.

But for those who must do their adventuring from an armchair, Pilchuck, the Life of a Mountain, will serve as a lively, enjoyable guide.

Although the book is out of print, copies are available in libraries and through online booksellers.

    Henry Wentworth Higman and Earl J. Larrison, Pilchuck, the Life of a

Mountain, illus. by Edmund J. Sawyer (Seattle: Superior Publishing, 1949)

Look here for a list of libraries in this region that have copies:

http://www.worldcat.org/title/pilchuck-the-life-of-a-mountain/oclc/8991821

Download the book to your computer:

http://www.whoseebook.org/dtqio_pilchuck-the-life-of-a-mountain-pdf.pdf