"The Flood Advisory will expire at 7 p.m. this evening for a portion of southwest Michigan, including the following area, Cass MI. Deciphering advisories, watches, and warnings: Understanding weather alertsFlash flood warning: Take action! A flash flood warning is issued when a flash flood is either imminent or already occurring. Flood warning: Take action! Flood advisory: Be aware:A flood advisory is issued when flooding is not expected to be bad enough to issue a warning.