fáwë vb. "snow" (GL:35; rather lossë in Tolkien's later Quenya)
Quenya
niqu-
verb. to be chill, cold, freeze (of weather), snow
nicu-
verb. to be chill, cold, freeze (of weather), snow
hel-
verb. to freeze (of water)
fáwë
snow
hriz-
verb. to snow
In notes written around 1959, Tolkien experimented with various roots for impersonal “snow” verbs, first giving the aorist form of a derived verb Q. hrisya “it snows” < hriþya from the root √SRITH, then the present tense form of a basic verb Q. hríza “it is snowing” from the root √SRIS (PE17/168).
Neo-Quenya: The basic verb form †hriz- is likely archaic, since z usually became r in Quenya’s phonetic development. In this case, though, I suspect the medial z dissimilated back to s after the hr, since Quenya disliked repeated r’s (PE19/73-74). This occurred, for example, with the verb ras- “stick out” < †raz- < √RAS.
Thus, I would use modern Quenya hrise “[it] snows”, hrinse “[it] snowed”, ihrísie “[it] has snowed”. Since this is an impersonal verbs, no explicit subject is required.
lossë
snow
lossë (1) noun "snow" or adj. "snow-white" (SA:los, MC:213, VT42:18); losselië noun"white people" (MC:216, PE16:96)
niquë
snow
niquë (2) ("q")noun "snow" (NIK-W)
olos
snow, fallen snow
†olos (2) noun "snow, fallen snow" (prob. oloss-, cf. the longer form olossë below; this form should be preferred since olos also = "dream, vision") (GOLOS)
olossë
snow, fallen snow
†olossë noun "snow, fallen snow" (GOLÓS, LOT[H])
hris-
verb. to snow
A verb in the Quendi and Eldar essay from 1959-60 glossed “be chill, cold (of weather)” (WJ/417). It also appeared in some etymological notes from around 1959 as a derivative of the root √NIK(W) and with the glosses “to snow, it is chill, it freezes” (PE17/168). In this 1959 note Tolkien gave several inflected forms making it clear nicu- was an impersonal verb: nīqua “it is freezing”, nicune “it snowed, froze”.
Neo-Quenya: For purposes of Neo-Quenya, I’d mostly use nicu- as an impersonal verb for cold weather: nique “it is cold, it is freezing”. For the freezing of water or similar substances, I’d use ᴺQ. hel-. For “to snow” I’d use ᴺQ. hris-, a modernization of archaic †hriz-.