I have received several emails from folks asking about the meteorology of aircraft turbulence and how to avoid it if possible. Where is the best place to get aviation turbulence forecasts?
I don't claim to be an expert in this area, but let me give you some meteorological insights and practical advice. Any pilots who read this can chime in.
Which Aircraft Should You Fly?
Not all aircraft handle turbulence equally. Bigger, heavier aircraft (like the Boeing 747, Airbus 380) don't bounce around as much. Something called wing loading, the ratio of the weight of the aircraft to the wing area, has a large impact, with larger wing loading reducing turbulence. Big, heavy aircraft have large wing loading, but so do some newer planes like the Airbus A320neo,
Some aircraft, like the Boeing 787 and the Airbus A320neo, have active systems that modulate control surfaces to reduce the bumps.
So if you dislike turbulence and can choose your aircraft, pick aircraft such as the Boeing 787 or Airbus A320neo if you can.
Where should you sit?
Generally, it is best to be over the wings, while the back of the aircraft is the worst. Over the wings you are near the aircraft's center of gravity and there is less lateral motion
When Should You Fly?
In general, the earlier the better.
Heating of the ground produces surface-based turbulence than can cause light to moderate turbulence in the lowest few thousand feet. This is particularly noticeable when landing in arid regions during the summer.
Cumlus convection and thunderstorms are even more important and are often driven by surface heating. Thus, there are much more of a problem latter in the day.
Aircraft Turbulence Apps
If you want to prepare yourself before flying, the are several free apps that allows you to view forecasts of aircraft turbulence.
Most of these apps use the turbulence predictions made by the NOAA Aviation Weather Center--another reason why NOAA is important.
They start with NOAA global model predictions and then calculate parameters related to aviation turbulence, such as vertical wind shear. A key forecast parameter related to turbulence aloft is called Turbulence Forecast Potential, with an example shown below from the website of turbulenceforecast.com).
A very easy to use aviation turbulence site in call Turbli.com. You tell them what flight your are on and they provide a predicted timeline of turbulence on your flight (see below).
How good are these forecasts? I have used them dozens of times and have examined some of their verification statistics.
They are useful, but far from perfect. Why?
First, the NOAA global model model forecasts are imperfect, and yes, it is rated the fourth best in the world.
Second, the resolution (13-km grid spacing) is too coarse to get fine-scale features and it does not do well with thunderstorms.
Third, the connection between predicted weather and turbulence is imperfect.
Fourth, the route (both horizontally and vertically) taken by aircraft are often different than assumed in the projections.
So consider it useful guidance.
Finally, if you are interested in seeing where turblulence is being observed at a time, you can view pilot reports (call pireps), which are available in text or plotted on a map (see below).
I find pireps very useful for research. For example, I am doing an extensive examination of the meteorology of the LA wildfire and the severe turbulence reports suggest intense mountain wave activity.
It's entirely impractical for the average passenger to spend their time trying and avoid turbulence. Professional pilots are paid to, among many other things, know where turbulence might show up and do their best to avoid it. Just let them do their jobs, keep your belt fastened, and enjoy the ride!
ReplyDeleteCliff, very helpful information, as usual. I have used several of the tools many times before. Although you can't prevent the turbulence on the flights you have chosen, being aware on what might occur is often reassuring.
ReplyDeleteTurbulence, particularly Clear Air Turbulence (CAT), is notoriously difficult to predict and avoid. All professional pilots work very hard with dispatchers, weather product suppliers, ATC and other pilots to avoid it. It has a habit of moving and changing both laterally and vertically that is all but impossible to predict. While we do that best we can, it's an imperfect science. Other sorts of turbulence such as convective (clouds) and thermals can be avoided in most cases but at some point you have to go through that stuff to land, take off or just get where you are going. We try very hard to minimize the time spent in those regimes but it's not realistic to avoid them completly. As Cliff stated, early mornings can reduce much of the convective/thermal bumps but not all. Convective turbulence is also part of air mass interaction and that can happen any time of day. I think about the best you can do is avoid flying when there is significant weather at or between your points of travel and sit at the wing or forward of it.
ReplyDeleteAdding to what Prof Mass wrote: early morning flights are smoothest but evening flights are next best especially for thermal-driven bumpiness like Phoenix and Palm Springs. While overwing seats minimize uncomfortable yaw motion, front of the bus is next best on many planes… back rows get whipsawed a bit. Leeward of the Sierras and Rockies (Reno, Denver) are almost always bumpy in the descent but usually smooth out in the last couple thousand feet above the runway. At cruise altitude, the bends in the jet stream are often where non-terrain-related turbulence lurks.
ReplyDeleteFor what it’s worth, the actual risk of turbulence is exaggerated in the minds of many nervous passengers. Generally speaking it is not a threat to the airframe or to safe landing, but it is a big threat to flight attendants walking about serving from a heavy drink cartand to unbuckled passengers. If you stay buckled in and focus on figuring out what meteorological phenomena are causing the turbulence, it might be less unpleasant. (But I hate rollercoasters so who am I to pontificate…)
Also, don't forget that we are about to hit tornado season, which means violent cyclones, wind, lightning etc and they will begin to occur during the afternoon hours, often lasting well into the evening/overnight hours and run mostly during spring/early summer, then we have hurricanes that come mid to late summer into fall.
ReplyDeleteI'm very certain most pilots will figure most of those out and do their best to circumvent them as much of possible. This is typical for Tornado Alley/flyover country, or for hurricanes, mostly Florida and the gulf coast states.
But generally speaking any thunderstorm will occur mid to late afternoon due to daytime heating.
Very interesting post. Always much to learn (and impress my friends :) ). Thanks!
ReplyDeleteWhile Sunday’s atmospheric river brought abundant precipitation to Whatcom County (probably a top-10 rainiest March day at KBLI), it also resulted in a remarkable dearth of sunlight by late March standards. I measured just 1.38MJ/m^2 total solar energy at my location in Bellingham with a maximum irradiance value of only 81W/m^2 making for the darkest day I’ve observed so late in the wet season. By comparison, I measured 15.38MJ/m^2 cumulative solar energy on 3/24/24 with a maximum irradiance value of 636W/m^2.
ReplyDeleteAviationweather.gov also provides detailed turbulence forecasts, which may be where turbulenceforecast.com is getting its info as the maps look identical. The .gov site allows you to change altitude and project out several hours into the future. I use it to help figure out how much anti-anxiety medication to take for a flight!
ReplyDeleteKBLI measured 1.19" of rainfall on 3/23 - the 6th rainiest March day on record at that location and the rainiest March day since 3/30/2011. With plenty more precipitation on the way, for many Western Washington locations, March 2025 will be the first March with above normal precipitation since 2017. In fact, if the current forecast verifies, this could easily be a top-5 wettest March at KBLI and probably other sites as well.
ReplyDeleteIt's also looking like the 2-day total precip at KBLI for 3/23-24 will rank within the top-5 2-day totals for March - possibly the rainiest 2-day period during March in more than 40 years.
ReplyDelete1.45 inches of rain in 24 hours in Gig Harbor on 3/23 with another .25 since midnight giving a storm total of 1.70" of rain in 36 hours! Yet WFMO Seattle ending up with 0.1." Looks like the rain shadow was in-effect from near due west flow. Amazing localized totals. And now thunder? CAPE and Lapse Rates look high for our areas. Looking forward to your nest blog on the heat and possible thunderstorms!
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