ALERT: Flood Watch for all islands from Wednesday through Thursday, high surf and winds expected

Hawaii Independent Staff

HONOLULU—The National Weather Service in Honolulu has issued a Flash Flood Watch for all islands from the morning on Wednesday, January 12 through the afternoon on Thursday, January 13.

A strong cold front approaching from the northwest will bring the threat of heavy rainfall and flash flooding. The western portion of the state will see the greatest flood risk Wednesday with a continued threat of heavy rain on Thursday.

A Flood Advisory has been issued for Oahu until 4:45 p.m. on Monday, January 10. At 1:30 p.m. today, radar showed moderate rain moving over Oahu from east to west. The showers are expected to continue through late afternoon.

A Flood Advisory has also been issued for Molokai until 6:45 p.m. on Monday, January 10. At 3:42 p.m. today, spotters reported heavy rain over Molokai moving east at 15 mph. The advisory may need to be extended beyond 6:45 p.m. if heavy rain persists.

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.

High Surf Advisory

The National Weather Service also issued a High Surf Advisory beginning midnight tonight, Monday, January 10, for North and West facing shores of Niihau, Kauai, Oahu, Maui, and Molokai.

A series of storms moving across the western and central Pacific have generated large west-northwest swells that will arrive tonight and last through Wednesday, January 12.

Rough surf created by a mix of long and short period swell will increase further on the night of Tuesday, January 11, possibly pushing surf to warning levels.

Waves along north-facing shores will increase to 15 to 20 feet. West facing shores will increase to 10 to 15 feet. Surf will rise on Kauai and Oahu during the evening and surpass advisory levels after midnight tonight.

A High Surf Advisory means that high surf will affect beaches in the advisory area, producing rip currents and localized beach erosion.

Small Craft Advisories have also been issued throughout the state as locally strong and gusty winds near the front combined with the northwest swell will create dangerous seas. The large swell will linger through Wednesday then gradually diminish.

Wind Advisory

A Wind Advisory is also in effect for Haleakala Summit and Hawaii Island summits through midnight tonight with southwest winds from 30 to 40 mph with gusts up to 50 mph. Operatrs of high profile vehicles should drive with caution. Visitors to the summits should prepare for windy and cold conditions.

A Wind Advisory means that winds of 30 mph are expected. Winds this strong can make driving difficult. Use extra caution.

For updated information, visit http://www.prh.noaa.gov/hnl/