Saturday, January 7, 2012

Why N. Utah's 'East Winds' Aren't Always From the East

Northern Utah's "canyon winds," or "east winds" are legendary. 
The last such wind event struck  April 30, 2016 to May 1, 2016  -- and before that, on April 9, 2013.
Residents will also not soon forget the much worse winds -- Dec. 1, 2011, when hurricane force winds hammered Davis and Weber counties in particular, causing a massive cleanup and millions of dollars in property damage.
(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.)
Although the Dec. 1 winds were then the first in 12 years to hit, the winds were NOT always eastern winds and they scoured the Salt Lake Valley.
The key question is "why?"
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 well-known TV meteorologist, 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.

1 comment:

  1. If we get an east wind right now, that will mean a power outage in this cold, arctic weather.

    No one should be without a good standby generator, even if they have financial challenges. Most people feel that they simply cannot afford a good standby generator.

    I am having a fund drive to try to get standby generators for everyone in my neighborhood (ward area) here in Kaysvile, Davis County, Utah. We need to be able to stay warm and to stay in our own homes if the power goes off.

    We are having deadly cold temperatures right now, so I hope a bad East wind will not develop.

    Most people don't feel that everyone having a generator is a very serious need, but it is.

    Please contact me for information on a fund drive I am running to get generators for my neighborhood and for me who has some health challenges.

    I think what I am trying to do is reasonable if you read it closely. I don't want to take the risk of people freezing to death this winter, have water pipes breaking, and not being able to go on with their lives while the try to ride out a power outage.

    Please contact Marilyn Dinger at for more information.