Are your ready for a non-conventional explanation? Other explanations (advection in this instance) are not wrong as much as they are incomplete and lacking in details (sometimes important details) that are necessary to properly conceptualize atmospheric flow.

First some basic facts:

1) Our atmosphere is a big sponge for energy. This is the result of the friction of gases.

2) Consequently there is a large amount of energy in our atmosphere. The molecules are moving very fast, 900 miles an hour. We generally refer to this energy as air pressure. Believe it or not this energy (air pressure) is the source of the energy that powers winds--but maybe not in the way you might first assume:

3) The means or mechanism by which the energy in air (air pressure) is converted to wind involves aerodynamics.

4) Aerodynamics requires a surface that can reflect energy and/or isolate a flow from the friction of gases.

5) Due to the friction of gases, streams, like jet streams, could not exist in our atmosphere unless there was some way to isolate the stream-flow from the friction of gases. Again this involves the existence of a surface that can reflect energy into a stream flow--aerodynamics.

6) At and along boundary layers between moist air and dry air, with the inclusion of energy (wind shear) a plasma phase of H2O emerges. This plasma provides the surface that reflects energy into a stream flow.

(BTW: this "plasma" is plainly observable as the "thick air" that comprises the cone/vortex of tornadoes.)

7) This plasma tends to spin around the central axis of flow producing a tubular structure (a vortex) that further isolates a stream flow (the jet streams) from the friction of gases. This isolation and the above mentioned reflection of energy into a stream flow is the reason for the high winds of the jet stream.

8) The jet stream is located at the boundary between the stratosphere and the troposphere. The reason it is located here is because, as explained in #6 above, the plasma must have a boundary between moist air and dry air and that is what exist between the very dry stratosphere and the relatively moist troposphere.

9) This is not a perfect system in that eventually the moisture falls out and the structure of the jet stream breaks down, this causes winds (advection) that generally track the same direction as the jet stream. So, in a sense, the jet stream, being a leaky pipe of directed, focused energy, drags the rest of the atmosphere along. And this explains why prevailing winds are prevailing.

10) Additionally, the jet stream itself will tend to track down producing storms. Storms pull more moisture up higher (sometimes all the way up into the lower stratosphere) and this functions to re-establishes the moisture content in the upper troposphere.

11) Sometimes these, above mentioned, down tracking jet streams will encounter a moist/dry boundary layer in the lower atmosphere. This can result in the re-invigoration of a jet stream, supplying it the resource (moist/dry boundary layer) it needs to grow. And this can, sometimes, allow it to grow all the way to the ground to produce a tornado.

12) Mitigating tornadoes can be achieved by interrupting the smoothness, length and integrity of moist/dry boundary layers in the lower troposphere.

It is important to note that without the H2O-based plasma that I mentioned above jet streams (and tornadoes) couldn't possibly exist because friction of gases would prevent the conservation of energy (wind speed) that makes them possible. And since the jet streams are what powers the prevailing winds, the prevailing winds too would not exist without this H2O-based plasma. And this is all a good thing because the (usually) relatively calm weather conditions that we experience on this planet also would not exist (theoretically).

The general misconception is that prevailing winds are produced by differential air pressure. As I explained above, although this is not completely mistaken in reality this type of flow is generally not able to overcome the sponge effect of the friction of gases.

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