‘Potent’ storm system threatens to wallop Hawaiian islands

The National Weather Service warns that a “potent winter storm system will bring a multi-faceted threat for significant weather hazards” to all Hawaiian islands starting Wednesday night.

The threats include heavy rain, flash flooding, damaging winds, severe thunderstorms on all islands, and snow and ice on Hawaii island summits, according to weather service forecasters in Honolulu.

“Damaging gradient and downslope winds will be possible, particularly to the north and northeast of the terrain from late Wednesday night through Friday, especially over the smaller islands,” NWS said in a special weather statement. “In addition, heavy rain capable of producing flash flooding is expected to affect the entire island chain during this time.”

The public is urged to monitor forecasts, and to be prepared should flash flood warnings be issued.

The weather service today issued:

>> A flash flood watch for all islands from Wednesday evening through Friday morning. “Flood prone roads and other low lying areas may be closed due to elevated runoff and overflowing streams. Urban areas may receive more significant flooding and property damage due to rapid runoff.”

>> A high wind watch for all islands Wednesday evening until Thursday night with southwest winds 20 to 35 mph with possible gusts up to 55 mph. “Damaging winds could blow down trees and power lines. Widespread power outages are possible. Travel could be difficult, especially for high profile vehicles.” Forecasters said the strongest winds will likely be across windward and mauka areas of Oahu and Kauai, but parts of Maui County and the Big Island could also see strong winds.

>> A winter storm watch for Hawaii island summits late Wednesday night through Friday morning. “A light glaze of ice is also possible on wet surfaces as temperatures drop below freezing.”

>> A gale watch for Kauai waters from Wednesday evening to Thursday afternoon due to strong winds, which can cause hazardous seas and reduce visibility for boats.

The storm system threatening Hawaii comes from an unusually strong low pressure system northwest of the state that will pass a couple hundred miles north of Kauai on Thursday, then drag a cold front east through the islands through Friday, according to the weather service.

“Intense rainfall rates are likely especially over the typically drier south and southwest facing slopes, where the greatest rainfall totals are expected,” forecasters said. “Finally, there is an enhanced risk of strong to severe thunderstorms with the primary threat expected to be damaging wind gusts, particularly over the smaller islands.”

Kauai County officials are urging residents to stay vigilant and avoid outdoor activities in flood-prone areas such as hiking trails, rivers, streams, and low-lying areas.

NWS officials urge residents to take precautions to protect property before the storm hits, and to tie down loose objects or move them to a sheltered location.

Hawaiian Electric officials said the company was monitoring the weather and encouraged residents to check their emergency preparations and prepare for the possibility of power outages. They said those preparations should include:

>> Checking emergency equipment such as flashlights, generators, battery-operated radios, light sticks, and lanterns to be sure they are operational.

>> Buying extra batteries.

>> Having a battery-powered radio on hand to listen for updates on the weather conditions.

>> Making sure portable generators are in a well-ventilated area outside the home, and carefully follow all instructions in the manufacturer’s manual.

>> Turning refrigerators and freezers to their coldest settings in case power goes out.

>> Turning off and unplugging any unnecessary electrical equipment, especially sensitive electronics in case of a power outage.

>> And assume downed power lines are energized and dangerous, and stay at least 30 feet or more away from all power lines.

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More Hawaiian Electric preparation and safety tips are available at hawaiianelectric.com/stormcenter.