Heavy rainfall warning

A flash flood watch (SAME code: FFA; also referred as a "green box" by meteorologists) is issued by the National Weather Service when conditions are favorable for flash flooding in flood-prone areas, usually when grounds are already saturated from recent rains, or when upcoming rains will have the potential to cause a flash flood. These watches are also occasionally issued when a dam may break in the near future.

Countries such as Australia also issue similarly worded warnings.

In the event that a flash flood watch is likely to lead to a major flash flood disaster, enhanced wording with the words This is a particularly dangerous situation (PDS) can be added to the watch; this is occasionally issued.

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