You may see their trunks arching in the woods Years afterwards, trailing their leaves on the ground Like girls on hands and knees that throw their hair Before them over their heads to dry in the sun.
The speaker paints us a vivid picture of what these "broken" trees look like when the snow thaws and their leaves come back.
The speaker says that the trees look like girls drying their hair in the sun.
Those of us with short hair may not realize that long hair takes forever to dry. Now imagine drying hair in the days before hairdryers.
These country girls that the speaker describes are on their hands and knees, bending their heads down so that the sun can dry their hair.
But I was going to say when Truth broke in With all her matter-of-fact about the ice-storm,
We see that the speaker got a little distracted by talking about the image of girls drying their hair, but now he's back.
We're not sure what he has come back to. This might just be a poet's way of telling his audience that he's shifting gears to a new topic.
Also, whenever the idea of "Truth" enters into a poem, you should be suspicious.
Here "Truth" is associated with "matter-of-fact" in the sense of real-life observations about nature or amateur science.
That "Truth" becomes a part of the discussion should clue you in that the speaker might be testing the poetic waters for different ideas about facts, values, science, nature, and spirituality (a.k.a. metaphysics).