Now obsolete, but found in "Sir Gawain and the Green Knight," among other places:
Snitter: [Of obscure origin: cf. SNITE n.2]
intr. Of snow: To fall. Hence snittering ppl. a.
13.. Gaw. & Gr. Knt. 2003 ye snawe snitered ful snart, at snayped ye wylde. c1400 Anturs of Arth. vii, Thay ran to the roches,..For the snyterand [Douce sneterand] snaue, that snaypely hom snellus. 1888 ADDY Sheffield Gloss. 227 Snitter, to snow.
When we hear the snow or sleet pelting against the windows in the winter, we always comment that it's "snittering ful snart!"