Sentence:  Thus in a context in which there has been discussion of snow but mention of local conditions <WSD>is</WSD> new , dominant stress will probably be on here in it rarely snows here , but in a context in which there has been discussion of local weather but no mention of snow , dominant stress will probably be on snows . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)