There are many reasons why Jupiter has many storms.
One of them is this.
As we all know, Jupiter is the largest planet in the Solar System. But another fact about Jupiter is that Jupiter is also the fastest rotating planet in the Solar System, with a day of only less than 10 hrs. Combining this two facts, Jupiter's Coriolis effect is far more powerful than here on Earth, creating vortexes in the atmosphere of Jupiter. In addition to that, Jupiter has no solid surface, which makes this vortexes to move around the planet with no hindrances. Finally, Jupiter's internal is (although a mystery) has one of the most active cores in the solar system, only after the sun, which generates a lot of heat fueling the vortexes, or storms. There's so much energy on this storms, and plenty enough, that some like the Great Red Spot has been blowing around the planet for 500 years.
