Haw. Rev. Stat. § 398-5: Notice.

In any case in which the necessity for family leave for purposes of birth or adoption of a child or providing care to a child, spouse, reciprocal beneficiary, sibling, or parent is foreseeable, the employee shall provide the employer with prior notice of the expected birth or adoption or serious health condition in a manner that is reasonable and practicable. Requests for family leave shall include evidence that the employee has submitted the request and provided required data in accordance with section 398-9.5.