From the Cliff Mass Weather Blog
Cliff Mass
Many folks are flying this summer and most are not fans of in-air turbulence.
So which airports are most prone to turbulence and why?
And if you are flying to one of these destinations, how can you minimize the risk of a bumpy flight?
All will be revealed in this blog.
Recently, the aircraft turbulence website, Turbli, published its analysis of the most turbulent airports in North America (see results below). The top two are Portland and Denver.
I can certainly confirm the results for Denver, to which I fly all the time (the National Center of Atmospheric Research, NCAR, is in nearby Boulder).
So why are landings and take-offs so turbulent for these locations?
It is all about geography and nearby terrain barriers.
Portland
As shown in the map below, Portland Airport (PDX) is essentially due west of the Columbia River Gorge.
During winter, cold air and high-pressure build to the east of the Cascades, while low centers approach from the west. The result is a strong pressure difference across the Cascades that produces strong low-level easterly winds in the Gorge that reach the airport (see model simulation below).
While the winds are strong and from the east at low levels, the winds above are generally westerly (from the west). This produces a strong vertical wind shear (winds changing rapidly with height.
Strong wind shear is a principal driver of turbulent motions. Summer conditions are less conducive to Portland airport turbulence.
Denver
Denver Airport (KDEN) is northwest of the city and just east of the Front Range of the Rockies (see map).
The Rockies are turbulence generators throughout the year.
During summer, and particularly from June through early September, thunderstorms develop over the Rockies during the late morning and early afternoon and then drift towards the airport. Thunderstorms produce lots of turbulence.
Check out his satellite picture for midday on June 23rd…you can see the cumulus clouds bubbling up on the Front Range. Fly in from Seattle and you will fly through these clouds and will bump around considerably.
If you want to avoid summer turbulence at Denver, FLY IN or OUT EARLY before the thunderstorms rev up. My rule of thumb: don’t fly in or out of the DIA after 11 AM during the summer.
There are few such thunderstorms during the winter, but there still is plenty of turbulence, this time from strong mountain waves downstream (east) of the Rockies (see schematic below). Such mountain wave turbulence is encouraged by strong westerly winds approaching the crest of the Rockies for the west, a very frequent situation during the winter!
Such mountain wave turbulence can be extreme.
Happy flying!
An account of a B-52 with tail sheared off in the Denver-class turbulence.
https://theaviationist.com/2021/01/11/that-time-a-b-52h-stratofortress-bomber-lost-its-tail-over-new-mexico-but-managed-to-land-6-hours-later/
I remember that event. It was caused by CAT: clear air turbulence. We had a comment board in flight school (many years later) that displayed a photo of the tailless B-52 and requested comments. One individual wrote: “Get the CAT not the copy CAT.” That was the then commercial promotion of 9-Lives Eveready Batteries.
This is actually something that needs explained? Have none of these people ever done an insertion by helo,,,,, Oh, Yea, No. Never mind.
Sure, every time I play COD
Increased turbulence was one of the arguments against moving the Denver airport out further east, even though it was only by a few miles. This concern was offset by all of the land purchases made by political insiders before the decision to move the airport was made.
And the curious non-straight path of the new highway to the airport, named after a still-living at the time politician, Federico Pena.
Toll highway
flying north out of rocky mountain metro BJC we started our turn to the east to head home and promptly dropped 300ft. thankfully always bring extra towels.
Cliff forgot to mention the most important recommendation: always fly with the seat belt fastened.
Cliff, you say Denver Airport is northwest of Denver, but both my memory and your map show it to be northeast.
Some years ago when I was at a meeting in Portland I rented a Cessna to fly around and see amongst other things Mt St Helens. During the check out with a local instructor we flew over an airfield in the Columbia River Gorge (I think Mt Hood), he warned me not to try to land there because of the turbulence!
The mentioned Wave over the Rockies produce spectacular lenticular clouds and some of the best soaring in the world from Colorado Springs up to Fort Collins. World records have been made on altitudes achieved by the sailplane pilots.
The author discussed and to some degree conflated two kinds of turbulence – rotors forming downwind of mountain ranges, and turbulence due to wind shear caused by other factors. The former is a function of where an airport is located relative to nearby high terrain and prevailing wind direction. The latter is not so much location specific, being more a function of local weather, and can occur at any airport under the right conditions. Either type of turbulence can cause a rough ride, at least, or in extreme cases damage the aircraft or even cause it to crash.
Wind shear is often created by thunderstorm cells located over or near an airport, or by the movement of strong frontal systems, or by uneven daytime heating of the ground (such as passing from rural areas to heavily developed areas during a hot summer day, as often occurs with airports located in nearby rural areas that service big cities).
Denver in particular, being both downwind of the Rockies and in a transition zone from rural to heavily developed metro Denver, is often subject to both rotor action and weather induced wind shear, making for lots of turbulent approaches to landing.
I remember one flight from Denver to Seattle when I worked at Boeing. I swear the pilot was a 4WD Jeep driver who loved rough roads. He found every deep pothole in the road on that flight!
For many years I flew on commuters out of Inyokern Airport to LAX. I’ve flow into and out of most of the US airports including DIA I can’t count the times, and I’ve seen nothing close to Inyokern (INY) for brutal non-storm turbulence. The Sierra Wave is no joke. Inyokern Airport is the old Navy NOTS field – long ago the Navy wisely moved about 10 miles east. There is an interesting old book called “Riding the Monster” concerning the record breaking gov glider flights in the Sierra Waves.
I mean – (IYK)