Speaker or Narrator, and Point of View
Omniscient poetic voice
Form and Meter
Unrhymed free verse tercets (3-line stanzas), 3-5 stressed beats per line
Metaphors and Similes
The snowman is a metaphor for the man with a "mind of winter" who has "been cold a long time." It is inanimate and cold, signifying how inhuman an observer would have to be in order to suppress all subjective perceptions.
A "mind of winter" is also a metaphor for this condition: a mind so like winter that cold blankness is a default.
Alliteration and Assonance
Alliteration:
"One must have a mind of winter" - double /m/ sound
"listener, who listens in the snow" - repetition of "listen" along with /s/ sound of "snow" and "place" from previous line
"nothing himself" / "Nothing that is not there and the nothing that is" - repetition of words, /n/ sounds and /th/ sounds
Assonance:
"distant glitter" - short /i/ vowel
"same bare place" - triple long /a/
Irony
We know ironically that the observer who tries to completely strip away all his own perceptions will fail to do so; or else he is not human to begin with, which is the central paradox of the poem.
Genre
Modernist poetry
Setting
Winter forest; or, in the observer's mind
Tone
contemplative, philosophical, reflective
Protagonist and Antagonist
The observer, vs. his own biased perceptions
Major Conflict
The observer tries to overcome subjectivity to see nature as nothingness.
Climax
The poem builds slowly to the last stanza, where Stevens finally tells us that the listener and the landscape he is in are both "nothing," and all differences are collapsed into that unifying void. The poem is also one long sentence, so Stevens' grammatical use of delaying clauses increases the sense of building towards the finale.
Foreshadowing
Not true foreshadowing, but the first line: "One must have a mind of winter" creates anticipation for us to learn what that means and what that condition will achieve.
Understatement
"And have been cold a long time": this coldness must be essentially bottomless, since the person must be as cold as winter
Allusions
N/A
Metonymy and Synecdoche
N/A
Personification
N/A
Hyperbole
N/A
Onomatopoeia
N/A