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!