This word appeared as ᴱQ. lūre “dark weather” in the Qenya Lexicon of the 1910s as a derivative of the early root ᴱ√LUVU; it had a stem form of {lūri- >>} lūre- (QL/57). It also appeared as lūre in the contemporaneous Poetic and Mythological Words of Eldarissa (PME/57).
Neo-Quenya: A similar root √LUB “shadow, darkness” appeared in Tolkien’s later writings, so I think this word can be salvaged as ᴺQ. lúrë from primitive ✱lubrĭ. If so, it would be a rare example of the ancient br not undergoing metathesis to rb, but instead vocalizing before the following voiced consonant: ✱lubrĭ > luβre > lūre.
lúrë noun "dark weather" (LT1:259)