With fall comes the wind to Central Oregon

With good reasons Nanci Reuter admitted "I don't like wind anymore!"

It was nearly a year ago when hurricane-force winds whipped through Sisters toppling huge ponderosa pines and spooking residents. A limb from a tall pine, torn loose by the wind, struck and injured her husband, John, outside the Reuters' Fotos in a Flash store.

On that Halloween Day wind gusts of 82 miles per hour (seven m.p.h. over what is termed "hurricane-force") were recorded by Douglas Sokol at the Sokol Ranch southwest of Sisters.

However, winds of that ferocity, while not too uncommon on the exposed headlands on the Oregon coast, are rare in Central Oregon.

Winds that swept across central Oregon last Wednesday, October 25, must have rekindled memories in Sisters of the destructive storm of almost a year ago. However, estimates of wind speed in Sisters on October 25 were that maximum wind speed was about 45 miles per hour.

What is it about fall that brings windstorms to Oregon? Actually, severe winds have also occurred in winter and on occasion in spring.

Winds, air in motion, are caused by pressure differences between one place and another. The greater the pressure difference, the stronger the wind.

Typically in October, low pressure (called the Aleutian Low) forms in the North Pacific and is responsible for the fall and winter storms.

If moist, subtropical air moves northward and collides with a stream of cold air from the Gulf of Alaska (as occurred October 10, 1962), a deeper low pressure system develops .

By October 12, 1962, (Columbus Day) this low pressure which by then was located off the Oregon coast had an extraordinary low reading of 28.30 inches of mercury. Most home barometers do not record anything that low. The average sea-level pressure is 29.92 inches.

The storm center moved northward offshore, parallel but close to the Oregon coast. The consequences are now history. In Oregon and Washington the infamous Columbus Day storms where winds gusted to 116 m.p.h. on the Morrison Bridge in Portland, 127 m.p.h. at Corvallis and an estimated (the anemometer was destroyed by the wind) 175-200 m.p.h. at Cape Blanco, caused $170 million in damage, killed 45 people and blew down an estimated 17 billion board feet of timber.

Sisters, as did other parts of Central Oregon, escaped the brunt of the windstorm. Official peak gusts at the Redmond Airport were a moderate 47 m.p.h. Even so, the high winds downed 15 million board feet of timber on the Deschutes National Forest and caused widespread power outages in the Sisters area.

Since the Columbus Day storm there have been other damaging windstorms that have affected Central Oregon. The storm on Friday, November 13, l981 saw peak wind gusts as high as 52 m.p.h. in Redmond and 72 m.p.h. at Madras. The storm resulted in power outages in the Sisters and Camp Sherman areas.

On January 7, 1990 when wind speeds of 46 m.p.h. were recorded at Redmond, downed trees across the highways forced temporary closure of U.S. 20 west of the Santiam Pass and of Highway 126 between Eugene and the Santiam Pass.

Central Electric Co-op power outages affected customers in the Black Butte Ranch-Camp Sherman areas.

Back to last year. When asked how the 1994 Halloween Day "blow" compared with previous windstorms, Homer Shaw, Sisters resident since 1919, believed that it was, perhaps, the most damaging in Sisters.

However, Homer recalled that in 1931, when he was in high school, ferocious winds did considerable damage along parts of the Metolius River.

Newspaper reports stated that on April 22, 1931, beginning about 6:15 a.m. and lasting only about 10 minutes, freakish winds roared through the Metolius Valley, uprooting thousands of huge pines and either destroying or damaging some of the summer cabins along the river.

What are the meteorological conditions that would likely result in potentially-damaging winds in Sisters? The answer is a duplication of what occurred a year ago -- rapidly falling barometric pressure in Sisters and to the east followed by rapidly rising pressure to the west of the Cascades.

Such conditions would cause a rush of air down the east side of the Cascades, similar to what periodically happens in the Boulder area of Colorado.

Winds sweeping across the open meadows west of Sisters hit with full force the tall ponderosa pines in Sisters, as witnessed by the number of toppled trees near the Three Creeks Road last year.

As this column is being written, it appears that it will be only little ghosts and goblins, not wind, that will spook Sisters residents this Halloween.