The best response to the question regarding the effect of the words with w and o sounds (powders, Wood, Wool, Road) in the first stanza of Emily Dickinson's poem "It sifts from Leaden Sieves" is:
It suggests a soft, slow sighing, as of the winter wind.
This choice reflects the gentle, soothing qualities of the sounds and aligns with the imagery and themes of winter in the poem.