If you really, really care about the accuracy of airliner-altitude winds prediction, you can do the following:

Set up cameras all over the damn place. They watch (and can identify) contrails.

In the simple version, the system always assumes airplanes are flying in a straight line relative to the air they fly in.

Using a plane's GPS info (etc) you can tell what the winds are (doing) at the point in space+time that the airplane is traveling through.

But...

The contrail left behind can be used to understand what the winds are doing AFTER the plane has left; roughly, same space, but at a different time.

For example, if the winds are blowing at a constant speed and direction at a particular altitude, then the contrail just moves... left, right forward or back [note that a smart monitoring system can tell that a contrail is drifting in the direction of, or in the opposite direction of its "long dimension".]

But if the contrail bends or if the north half is getting scrunched in one direction while the south half is getting scrunched in the opposite direction, we can determine things about what the winds are doing in the area the plane has already passed.

Two cameras (e.g.) miles apart that observe the same contrail can cobble together some sophisticated conclusions based on their collective "three dee" understanding of what the contrail is doing.

If "winds aloft" data are the result of many many points of data that the airplane sends back (maybe every X seconds), based on GPS, the direction the plane points, and so on... then the extra data produced by this system can be of the same form, think of several "virtual" airplanes flying along the same path.

The data stream from these "virtual planes" is based upon the monitoring system and a whole bunch of AI dark magic. As the contrail dissipates and no real meaningful extra information can be deduced, the system just gives up. In other words: there are a series of "virtual planes" following the real plane, but as confidence falls off, the trail of "virtual planes" can only be so long, conditions depending.

Chop chop!