Update 1/30/19: This lounge has now reopened and is open for business.
The American Express Centurion lounge in Miami will be temporarily closed for a short period in January (expected to be approximately two weeks). The following explanation is listed on the official website:
The Centurion Lounge at Miami International Airport will be temporarily closed for a short period in January as we work to upgrade and expand the space. Please visit one of our partner lounges including Delta Sky Club® when flying Delta, or a Priority Pass™ Select lounge once enrolled.
Exact closure dates and duration will be shared closer to the date, according to a statement provided to VFTW.