Q: Why Do Storms Move From West to East? - Central Coast News KION/KCBA

Q: Why Do Storms Move From West to East?

A: Our KION Question came from Melissa in Salinas.  She asked us, "Why do storms move from west to east?"

Here's the answer from Central Coast News Chief Meteorologist Norm Hoffmann:

The simple answer is that it has to do with the rotation of the earth. The direction that weather moves depends upon what latitude you're at.  On the Central Coast, you're used to weather moving from west to east, but if you lived in the tropics, you might think that weather always moves the other way! The tropical regions have storm systems called "easterly waves" that move from east to west.

Because the North Pole is relatively colder than the tropics, there is a low pressure that develops over the north pole. That low pressure rotates counterclockwise, as do all lows in the northern hemisphere. That means that the air around it flows from west to east. Because of the rotation of the earth High pressure develops near 20 to 30 degrees north latitude (it changes with the seasons), but the air around high pressures rotate clockwise.

With these two working together, the air flows generally around the globe from west to east. Sometimes the jet stream moves north or south moving warm air north and colder air south, but generally it moves from west to east.

If the earth rotated the opposite direction, this would all be reversed, but there would still be regions where weather moves from west to east and other regions where it moves from east to west.