Tuesday, October 22, 2013

Wasatch Front Canyon Winds History: They Aren't East Winds Everywhere

                            The narrow mouth of Weber Canyon can produce strong wind gusts.


Hurricane force east canyon winds along the Wasatch Front are nothing new.
In fact, from 1959 to 1999, there were 26 such occurrences of damaging east winds.
So, they averaged about every 18 months for 4 decades and then disappeared for more than 12 1/2 years until Dec. 1, 2011.
The damage from these winds was mostly so extreme, because it had been more than a decade since the Wasatch Front had any such wind events and so the damage came all at once, mostly from overgrown trees.
Then, another such wind event struck on April 9, 2013. And, they struck again on April 30-May 1, 2016  -- the latest episode.

]The "new" average for these winds is more in line with about every two years, or more.
The year 1988 featured a record three such east wind events. There were also two such hurricane force canyon wind events in 1964, 1973, 1983, 1986 and 1997.
April 2, 1973 featured some of the strongest, sustained canyon winds. Those winds picked up a pole vaulting portapit mat and carried across Weber State University's Wildcat stadium as if it was cardboard.
We forget that these winds are a periodic part of nature along the Wasatch Front.
Technically, they are "downslope winds."
Northern Utah's "canyon winds," or "east winds" are simply legendary. 
However, depending on where you live, these winds are not necessarily east winds.
Although I built my cedar fence strongest on the east side, that was pointless, since strong east winds have never hit my house.
In fact, the Dec. 1, 2011 winds that struck my property were straight from the north. (And they broke 4 posts along my fence's northern side.)
I asked Dan Pope, a from Utah weather expert on KTVX-TV, to address the question on wind direction and why "east winds" aren't always east winds.
His explanation is intriguing and worth repeating, especially since no TV weathercaster has enough air time to provide this much detail.
Dan Pope's answer:
These ... winds were "mountain wave" induced. But, the topography does force the winds to veer with distance; and due to local hills, canyons and location they can change as they move away from the mountains. They also come in rolling as they slam the ground (spinning counter clockwise).
In North Salt Lake, I have always noticed a veering to the north, because the hills by and to the north of Eaglewood Golf Course, that force the eastward track around them to flow southward.
These hills are also are northeast-southeast oriented, and with City Creek Canyon on the other side, the winds likely skip over the flat area above Meridian Peak and are pushed away from the hills, protecting some of the upper Bench of North Salt Lake from the worst gusts, while Bountiful, Centerville, Farmington and areas northward are directly in line with the Wasatch Mountains, and the "wave" effect.
When we have these kinds of winds, there is usually a low pressure spinning to our south. The upper level winds come from the east or preferably the Northeast. And, at the surface, the pressure is much higher in Wyoming and lower in Utah. In a low pressure like this, sometimes a little warmer air is wrapped in above the mountain tops. This creates an inversion at 12,000 or 13,000 feet, and keeps any wind from rising--and creates a Venturi effect. 
Plus, the Uinta Mountains line up directly east of Bountiful and Davis County, so all wind get pushed eastward towards the Wasatch mountains from extreme Northern Salt Lake County and Davis County northward.
Rule of thumb is that winds will be 2 to 4 times higher than at mountain top as they "roller coaster" down the slopes; and they will hit beyond the base of the mountains 1/2 to 3 or 4 miles out towards the Great Salt Lake. Then they fan out, and can go in multiple directions.
To the south of Davis County, they fan to the south (a north wind) and northward the can even come in from the SE if a person lives more than 3 or 4 miles from the base of the Wasatch. But, more often than not, these winds veer to the south away from the Wasatch, because the surface pressure is lower to the south.
There are certain locations near the canyons and at the base of the Wasatch in Davis, and counties northward, where these winds can be severe right at the base. Bountiful, Centerville and Farmington, as well as NE Ogden, Brigham City and even Logan fall into this category.

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EAST WINDS WERE A PIONEER PROBLEM TOO:

Strong east canyon winds have been known to buffet the Wasatch Front, particularly Davis County, ever since the Mormon pioneers arrived in the late 1840s.
"East winds have come from time to time (in Davis County) ever since the people can remember, doing much damage to trees and roofs," states the history book, "East of Antelope Island," published by the Daughters of the Utah Pioneers.The first recorded incident of strong east winds comes from a diary of Daniel A. Miller, one of the earliest settlers in Farmington.
He recorded that the very first day his family arrived in the area -- the fall of 1848 -- there was a heavy east wind.
Early settlers created inventive ways to try to secure their roofs from these winds, but nothing seemed foolproof. One early Kaysville resident, John R. Barnes, made the east walls of his home four bricks thick to ward off canyon wind damage.
Prominent settler George D. Watt made a special wind storm shelter for his family, but he still had his home's roof blown off.
A strong east wind in the summer of 1854 actually performed a miracle. The canyon winds saved the day by blowing hordes of invading grasshoppers away from Davis County crops and into the Great Salt Lake, where they perished.
Hurricane-force east winds struck at least twice in the early 1860s, and the roof on the East Bountiful LDS Church had to be replaced twice.
After one such east wind, the Tuttle brothers from Bountiful jokingly inquired on Antelope Island if any missing hats had been found.
The east winds were a very feared and dreaded occurrence, especially in Farmington. It was canyon winds and water shortages that plagued many early Davis settlers the most.
Perhaps the saddest east wind incident took place in February 1864 when Elizabeth Rigby of south Farmington and her 18-month-old son, John, froze to death after being pinned against a fence by hurricane force canyon winds. Husband John Rigby had left his family to travel to Salt Lake City for medicine. Upon returning, he not only discovered the two deaths, but the home's roof was also blown off and 200 sheep, six horses, 10 cows and four pigs perished because of downed buildings and the frigid winds.
During a Nov. 9, 1864, visit to Farmington with Wilford Woodruff when the canyon winds were blowing, LDS Church President Brigham Young rebuked the winds in the name of the Lord.
Woodruff's diary reports that east winds did decrease substantially for some years afterward, perhaps as long as the late 1890s.
When Matthew Cowley reviewed Woodruff's diary in 1909 before its publication, he noted:
"In late years these winds have occurred in some of their old-time severity."
Strong east winds struck Davis County twice during 1896 and two more times in 1898. A fierce canyon wind in 1906 took the roof off the 2-year-old West Bountiful LDS Chapel.

Sources: Dan Pope, meteorologist, "East of Antelope Island" book, by Daughters of Utah Pioneers; "Weather and Climate" book, by Dan Pope and Clayton Brough.

(-Written by Lynn Arave and published in the Deseret News, April 23, 1999.)

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