ALERT: Flash Flood Warning in effect for Oahu, Flash Flood Watch for all islands through Monday
HONOLULU—The National Weather Service in Honolulu has issued a Flash Flood Warning for the island of Oahu until 6:15 p.m. on Sunday, December 19.
A Flash Flood Warning means flash flooding is imminent or occurring in streams, roads, and low lying areas and people in the storm’s path should move to higher ground now.
At 3:00 p.m., rain gages across the southeast portion of Oahu showed heavy ran falling at 1 to 2 inches per hour on already saturated ground. Radar indicates additional heavy showers moving over the the southeast portion of Oahu through at least 5:00 p.m.
Other locations in the warning include, but are not limited to Honolulu, Hawaii Kai, Waimanalo, Kailua, Kaneohe, and Waikane.
The Flash Flood Warning may need to be extended beyond 6:15 p.m. if flash flooding persists.
A Flash Flood Watch is still in effect for all islands through the afternoon on Monday, December 20. A very moist air mass moving northeast across the islands from the deep tropics is bringing widespread rain and heavy showers.
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.