Flood Watch vs. Flood Warning
A flash flood watch means a flash flood is possible in the area, because conditions are more favorable than usual for its occurrence. A watch is a recommendation for planning, preparation, and increased awareness (be alert for changing weather, listen for further information, and think about what to do if the danger materializes.)
A flash flood warning means a flash flood is imminent or occurring; take immediate action to protect life and property.
An urban and small stream advisory means to be alert regarding potential flooding of small streams, streets, urban storm drains, underpasses, and low lying areas.