The 7th phrase of the Lament of Akallabêth (SD/247). The subject bawîba is the subjective plural of #bawab “wind”. There is no verb, so the subjective here functions as the to-be verb “were”, as discussed on SD/429. The adjective dulgî is the plural of dulgu “black”, agreeing in number with the subject.
This sentence did not appear at all in the first draft. In the second draft of the Lament, it was simply the noun phrase dulgu bawīb “✱black wind” rather than a full sentence (SD/312). Curiously, the adjective in the second draft did not agree in number with the noun it modified.
The noun for “wind”, attested only in the plural (bawîb) and subjective plural (bawîba) forms (SD/247, SD/312). Its plural form indicates that it is a strong-noun (Strong I), so its final vowel must be short, but in theory it could be any of a, i or u, each of which would be replaced by long î in plural nouns. Nouns with identical vowels are more common, however, so ✱bawab is the most likely singular form, though as Helge Fauskanger points out (AL/Adûnaic) the normal form could also be the weak noun ✱bawâb with a poetic strong plural (SD/435).