ALERT: Heavy rains may bring flash flooding to Oahu, Hawaii Island

HONOLULU—The National Weather Service is asking Oahu and Hawaii Island residents to be prepared for possible flooding this Tuesday, November 1.

A strong upper level disturbance is causing a moist and unstable atmosphere, which can lead to heavy rainfall and flooding today.

A Flash Flood Watch is in effect through this afternoon for Hawaii Island.

A Flood Advisory was issued for Oahu at 10:39 a.m. this morning. Gauges at Palisades measured rain falling at two inches per hour. Stay away from streams, drainage ditches, and low lying areas prone to flooding.

For updated information from the National Weather Service, click here

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.

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.