Areal flood notifications are issued as warnings and not advisories. They are issued when flooding is prolonged and has developed gradually from persistent to moderate rainfall. These are issued as warnings rather than advisories because areal flooding can pose a threat to life and property.
Areal floods cause the ponding or gradual buildup of water in flood-prone, low-lying areas that include streams and small creeks. They occur more than six hours after the initial rainfall. An areal flood develops more slowly than a flash flood, which is flooding in low-lying and flood-prone areas that occurs within six hours after initial rainfall and also poses a threat to life and property.