Foreshadowing is a literary device in which a writer gives an advance hint of what is to come later in the story.
After ten threads most of the low-hanging fruit has been discovered and discussed. But this forum gets new members all the time, so feel free to post and identify foreshadowing passages, even if the foreshadowed events have already happened.
One through Nine...
http://asoiaf.westeros.org/index.php/topic/66352-moments-of-foreshadowing/
http://asoiaf.westeros.org/
Arya is the Last Hero, and Sandor is her/his dog. The whole thing is about Arya, with Sandor.
First bold is referencing Nymeria, obvious Arya connection and a parallel. It also puts a time frame to things. Eventually the narrow sea will run dry and Arya will lead the realm of men (or convince them) into the dried out seabed, as Nymeria lead her people to the sea to eventual salvation.
What she's doing, she's doing on Bran's orders. His whispers. She's going for a magical purpose