Yes it is, but I don’t think it’s too common in Ulster, people rather say “hallò” or “haigh” or “dè mar atà tù” etc. Btw it’s the use of “duit” in Dia duit” that is Ulster : “duit” does exist in other places, but not in Dia duit.
BáraÄ‹, m., to-morrowâ€¯; i mbáraÄ‹, to-morrowâ€¯; ar maidin i mb., next morningâ€¯; lá ar n-a á¸ƒ. (lá har n-a á¸ƒáireaÄ‹, Don.), on the morrowâ€¯; ar n-a á¸ƒ., on the morrow (F. F.)â€¯; ó ’ndiu go dtí i mb., from to-day till to-morrow, from day to day. (The nom. báraÄ‹ is not usedâ€¯; the first syllable in the obliqe cases is pron. mbáir genly, but mbáraÄ‹ is still heard in N. Con.)â€¯; ará¸ƒú i mbáraÄ‹, the day after to-morrowâ€¯; tá faid an lae i mbáraiÄ¡ ann, he is very tall.