The National Weather Service uses these terms to define threatening flood hazards:

• (AREAL) FLOOD WARNING - Flooding that occurs greater than 6 hours after causative event and is hazardous to either life or property or will cause a great amount of flood related problems * Issued mainly during the winter season
• (RIVER) FLOOD WARNING - Mainstem river or tributary flow rates exceed the flood flow rate or are forecast to exceed the flood flow rate as indicated in river forecasts from the CNRFC -OR- The magnitude of the flood changes to a higher category (i.e., minor to moderate, moderate to major) -OR- A dam has failed in such a way that the release of water will cause the downstream river to slowly rise and flood
• ADVISORY - Nuisance flooding that causes minor inconveniences is occurring or imminent (in urban areas due to poor drainage,or in low-lying areas)
• WATCH - A threat of mainstem river or tributary flooding during the next 36 hours -OR- Flooding mainly during the winter season, that is hazardous to either life or property, or will cause a great amount of flood related problems during the next 36 hours