meaning in context - What does “There she blows’” mean?

This question regards the sentence in the New Yorker’s (June 14) article “Lunch at Gitlitze” I quoted in my previous question, "“Battled-hardened,” Is this one of New Yorker's renowned idiosyncrasies?”

“When we walked into the restaurant, we immediately saw her – my father’s battled-hardened nemesis; a waitress named Irene. She was standing in back by the kitchen, a cigarette dangling from her mouth, one hand on her hip.. She and my father locked eyes like two gunslingers stepping on to a dusty street. “There she blows” my father muttered. “Try not to excite yourself,” my mother said.”

I’m not clear with what “blow” in “There she blows” mean. It looks like a slang usage of the verb, blow.

I consulted with OALED at hand to try to find out a pertinent definition to this phrase and the situation of the story – “She was standing in back by the kitchen, a cigarette dangling from her mouth,” and found out the following definition at the top out of more than a dozen of usages.

1. to send out air from the mouth.

Does “There she blows” mean “There she is smoking a cigarette,” or otherwise? Does “blow” here have a special implication? Is this a slang, or idiomatic expression?

Why did the mother of the author quickly react to this phrase of her husband by saying “Try not to excite yourself.”?

Answer

"Thar she blows" is what the lookout on a whaling ship would shout when he saw a whale surface and blow out its blowhole. It's used metaphorically in this case, probably with a vague allusion to the White Whale in Moby Dick, which was Ahab's nemesis; if the allusion is intentional (and I think it is), it means "I see my nemesis and am about to engage in a struggle with [her]."