Quite easy. The science dealing with the prediction of upper atmosphere winds is part of Meteorology...

Even at altitudes of 60.000ft and at a considerable disatnce from the launch point? Did not one balloon end up over Costa Rica? Clearly Chinese meteorologists need to sharpen up.

And yet apparently they have been coming over the United States for years now...without NORAD or the USAF being aware of it.

Well, without NORAD and the USAF saying to the public they've been aware of it..

I see in reports this AM in parts of the MSM that it's now being claimed the balloon was actually tracked from launch..

https://www.theguardian.com/world/20...e-spy-balloons

You mean like the RAF did in 1960/61?
Vulcans managed to enter US airspace not once but twice!

Two balloons with equal buoyancy launched from the same spot at the same time will very rapidly diverge, regardless of being at very similar heights at any one time. This is due to the inherent randomness of what might be generalised as turbulence in pseudo horizontal directions. Not that the divergence would be massive but it would increase with time and travel.

I have done the experiment professionally with three balloons on several occasions.

This implies that, however good the upper wind is known and forecast, precise "targeting" of a track to achieve an aiming point is beyond science unless the balloon has some means of applying horizontal thrust, thus increasing weight and decreasing payload.

I agree, over that distance, without some form of propulsion, I think "beyond science" is understating it!

I suppose that a track (or rather the altitude profile for a desired track) couldn't be targeted in advance, but the point is that the systems would be adaptive based on current position and real-time wind measurements. As I understand it, the development of sensors for remote observation of wind speed and direction is a key part of the systems. I don't have any special expertise to say what the possible navigation accuracy might be, but people in the DoD (and private industry) who know the technology think that it is worth funding. That suggests that it might have some value.

Jet streams involve clear air turbulence, so I was told. How does it feel at zero true air speed?

CAT is not necessarily a feature of jet streams, and has a variety of causes from the surface upwards.
The best practical answer might come from a hot air ballooner or a glider pilot near the stall in wind sheer conditions.

Unpleasant at an informed guess.

I am white knuckle self loading freight, having lectured on "Met. hazards to aviation" for three years. Too much information as they say.

I don’t think you have CAT in the jetstream. More in the boundary layers.

Very complicated!

CAT "more likely" on top, bottom and sides of jet, and where jet changes direction sharply such as trough or even ridge.

Looking for CAT reported by one aircraft by another aircraft has been likened to finding one fish in a shoal in an ocean.

I was privileged to work for a pioneer in post-WW II study of CAT. I think modern airborne radar at the right wavelengths will be the long term solution for a given flight ............ forecasting is much better than it was but will never be a silver bullet. Modern aircrew will know more about the vagaries of CAT than a long-retired forecaster.

I firmly believe in keeping my seat belt and flies closed on a flight. A visit to the loo will bring on severe CAT without fail.

There is a sure fire way of finding CAT. Start serving drinks in the cabin. Never fails on the flights I have been on.

Yes, the seatbelt sign switch, also referred to as the turbulence switch.

US intel assessing possibility that Chinese spy balloon’s path over US was accidental

Who'd have thought it ?

Janus? :)

A diplomatic attempt to give everyone an "out" and return to status quo ante balloon?

Now that was funny! :ok:

Your informed guess is correct. :E

I have done a lot of glider-towing in lee-wave conditions at Cowley Alberta, which is Canada's premier wave-soaring location*. Last October, I had some of the most severe CAT I have ever experienced, such that I am debating wearing a parachute in future! We normally try to tow towards the lower, southern end of the Livingstone Range, which generates the wave, to try and avoid the rotor turbulence.

However, on two occasions, very experienced glider pilots had to release because they had lost control and on another flight, I watched my pen floating in front of me for several seconds!

A very experienced tow-pilot at my club used to say "The rotor is not rough, unless you get rolled inverted!"

* See Cowley Canada's Diamond mine. There is a panorama on this page which shows the wooded lower ridge we aim for in order to minimize turbulence.

I’m astonished to read that you don’t wear a parachute as a matter of course. I know two people personally that have used them in gliders (wing not correctly installed and a midair collision) plus read many accident reports where they were used