The Maui News

Heavy rain with potential for flooding is forecast beginning Sunday for leeward parts of Maui and all of Lanai due to a kona storm.

There also is a high-surf advisory up until 6 p.m. today and a brown-water advisory for West Maui and the north shore.

The high-surf advisory is for north- and west-facing shores of Molokai and north-facing shores of Maui and is driven by a medium north-northwest swell, the National Weather Service said. North shores could see surf at 14 to 18 feet; west shores of Molokai, 8 to 12 feet.

The brown-water advisory posted by the state Health Department is the result of stormwater runoff entering coastal waters. The public is advised to stay out of floodwaters and stormwater runoff due to material from overflowing cesspools and sewers that could include pesticides, animal fecal matter and carcasses, pathogens, chemicals and flood debris.

Not all coastal areas may be impacted by runoff but if the water is brown, stay out, the Health Department advises.

The flood potential outlook issued by the weather service Thursday was due to a kona low pressure system expected to develop west of the islands late this weekend. The system is expected to linger into next week.

The slow-moving band of heavy rain could lead to flash flooding, the weather service said.

“While it is too early to provide specifics as to where and when the heaviest rain will occur, there is increasing confidence that widespread heavy rain will affect the islands by early next week,” the weather service said.

The advisory covered the southern flank of Haleakala, South Maui and a pocket of West Maui.

The forecast for today for Maui’s central valley is mostly cloudy with a 40 percent chance of rain in the late morning and afternoon. Light winds in the morning will pick up from the northwest, about 10 mph, in the afternoon.

High temperatures should range from 78 to 83 degrees with overnight lows of 62 to 67 degrees.