Wave generation and size

Does any kind person have a simple explanation for the following?

If you look at wave prediction maps, one notices that the biggest wave areas appear in the form of blobs. That is ten foot plus waves might be the near the storm center but the size decreases as the wave travels.

One would expect a wave to stay the same size unless acted upon by an outside force. Generally still air might be considered the outside force and thus you have a understandable reason for decreasing wave size. YET if the wind is moving in the same direction, why then would wave size decrease, I wonder?

Asking questions about a map that you looked at but didnt study??

Here you go Goof: The globs dissipate rather quickly as they travel(normal behaviour), until they reach a Steady State.