Answer:
A kind of weather that comes your way, but add a "D" and it will run away
The more of it there is, the less you see.
In we go, out we go. All around and in a row. Always, always steady flow. When we'll stop, you'll never known. In we go, out we go.
My first is a body of water. My second is me. My third came before. My fourth before all three. My fifth sounds like my first. My sixth is in a lake. Put all six together to make an animal that will keep you awake.
Walk on the living, they don't even mumble. Walk on the dead, they mutter and grumble.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.