Flash Flood Watch for Oahu, Niihau, and Kauai through Tuesday
HONOLULU—Be careful out there. The National Weather Service in Honolulu has issued a Flash Flood Watch for the islands of Oahu, Niihau, and Kauai through at least the afternoon on Tuesday, December 28.
A Flash Flood Watch means conditions may develop that lead to flash flooding. An unstable air mass may produce periods of heavy rain while saturated soil will increase runoff, maintaining the threat of flash flooding.
Rainfall and runoff will also cause hazardous driving conditions due to ponding—reduced visibility and poor breaking action.
When flash flooding occurs in streams, roads, and low lying areas, people in the storm’s path should move to higher ground. Do not cross fast flowing or rising water in your vehicle or on foot.
Flash floods occur during extended rainfall events or within a few hours after the rainfall, according to the Pacific Disaster Center. Generally, if rainfall is of long enough duration, it will eventually cause flooding along the rivers, creeks, and streams draining the catchment area where the rain is being collected. But if the intensity of the rain—the number of inches of rain falling in a given time frame—is too great for the stream system, including flood plains, to carry the water away, flash flooding occurs.
The words “watch” and “warning” are used for two different levels of flood alerts. A flash flood watch or flood watch means that flooding or flash flood is possible in the area. The basic message of a flood watch is exactly what it sounds like: “Watch closely, conditions suggest a high likelihood of flooding.” When the word “watch” is replaced by the word “warning,” flooding or flash flooding is imminent or already beginning to occur. If you are in a low-lying or flood-prone area, act immediately to ensure the safety of your family. When a warning is issued, it is too late to prepare property to withstand flooding. You may have only seconds to act.