High flow or overflow of water from a river is possible in the given time period. It can also apply to heavy runoff or drainage of water into low-lying areas. These watches are generally issued for flooding that is expected to occur at least 6 hours after heavy rains have ended.
a BoM product to alert people living or working in riverine areas of the possibility of flooding and to give them time to make preparations for that possibility
Flooding is possible within the watch area. Sometimes this is called a Flash Flood Watch or an Urban and Small Stream Advisory to indicate the possibility of rapidly rising water and flooding or high water on streets, underpasses and around storm drains.
This watch is issued by a local National Weather Service Office to indicate that there ia a potential of flooding in or close to the watch area. Those in the affected area are urged to be ready to take action if a flood warning is issued or flooding is observed. In flooding, the onset of flooding take place much slower (usually greater than 6 hours) than a flash flood. This type of flooding usually occurs with "train echoes" or slow moving thunderstorms, and can also occur with synoptic scale systems that last a relatively long period of time and encompass a large area. They are usually issued up to 12 hours prior to the possible flood event. These watches can vary in size depending on the size of the meteorological event.
indicates that widespread flooding is a possibility in or close to the watch area. These watches are issued for flooding that is expected to occur 6 to 12 hours after the heavy rains have ended.
A product issued by an NWSO (National Weather Service Office) or NWSFO (National Weather Service Forecast Office) to advise of the possibility that flooding will occur in a specified area over a period longer than six hours.
A Flood watch is issued when weather conditions are favorable for very heavy rain and flash flooding.
