Foot of rain triggers life-threatening flash flooding in part of Hawaii

Rainstorms that prompted an emergency proclamation in Hawaii this week are poised to continue producing life-threatening consequences from flash flooding, AccuWeather meteorologists say.

Hawaii Gov. Josh Green on Friday proclaimed a disaster emergency relief through April 22 in response to the heavy rains, flooding and landslides impacting the county of Kauai.

"The severe weather on Kauai has caused damage to our roads, bridges, and other infrastructure," he said in a statement. "This emergency disaster proclamation will help the state and county with the emergency response to the heavy rains, flooding and landsides impacting the people of Kauai."

The rains, which began Thursday, have triggered landslides in Kauai and have necessitated rescues from people trapped in their cars by flash floods, officials warned.

Standing water and blocked culverts are widespread across the island.

The storm will continue pumping tropical moisture over part of the Hawaiian Islands through this weekend, meteorologists said.

The storm is locally called a "Kona Low," which is a slow-moving storm (low-pressure area) in the part of the atmosphere where jets cruise.

"The Kona Low and its counterclockwise flow of air was positioned in a perfect spot to pump moisture northward over the region," AccuWeather Senior Meteorologist Matt Benz said. "The storm was located several hundred miles to the northwest of the islands."

The storm had unloaded nearly 12 inches of rain on the city of Lihue in Kauai as of late Friday evening local time.

Kauai is located on the northwestern part of the island chain. Fewer than 75,000 people live permanently on the island, which is largely remote and a resort-based community. There are several low-water crossings instead of bridges along some of the roads on the island. High water could make traveling through these areas very dangerous.

The climate on the island is diverse, and as is the case on much of the Hawaiian Islands, the wettest zones are on the northeastern sides, which are exposed to persistent northeast trade winds that transport moisture in from the Pacific. The southwestern side of the island is shielded from the mountains in the middle of the island and is desert-like in some cases.

"The Kona low produced and will likely continue to produce copious amounts of rain on Lihue, especially in the southwestern desert part of the island into this weekend," Benz said. "Dangerous conditions with a high risk of flash flooding, mudslides and other debris flows with washouts are likely."

As of Friday night local time, up to a foot of rain has fallen, with 6-10 inches in the desert part of the island.

"The Kona Low will slowly wander to the southeast this weekend and will continue to bring drenching downpours on Kauai while allowing the firehose of rain to crawl farther to the east over the island chain," Benz said.

The storm could bring 1-2 feet of rain to Kauai, with heavy rain shifting in and out over the island over the weekend.

The Island of Oahu, home to Honolulu, will get into the bands of torrential rain for a time with the risk of flash flooding and mudslides on Friday and Friday night before the firehose of moisture shifts westward and returns to Kauai for a time on Saturday, AccuWeather Senior Meteorologist John Feerick said.

Due to the shifting bands, parts of Oahu may get hit again with downpours and flash flooding late this weekend to early next week, Benz added. Maui may experience the downpours at some point, if not later Friday and Friday night, perhaps by early next week.

Aside from raising the risk to lives and property and spoiling vacations for some, rain is needed as large portions of Hawaii were experiencing abnormally dry to moderate and extreme drought conditions, according to the United States Drought Monitor.

The storm near Hawaii is not the same storm that is heading across California this weekend with areas of rain, mountain snow and gusty thunderstorms.