HONOLULU (HawaiiNewsNow) – Your HNN First Alert Weather Team has declared First Alert Weather Days through Sunday due to the threat of heavy rain and flash flooding for Oahu, Maui County and Hawaii Island.
We are monitoring a Kona low that has already produced rainfall that caused catastrophic flooding on Oahu’s North Shore.
The National Weather Service has also issued a Flood Watch for all the main Hawaiian islands from 6 p.m. Thursday through 6 p.m. Sunday.
A Flash Flood Emergency was issued for the North Shore of Oahu on Friday, but has been allowed to expire.
A Flash Flood Warning remains in effect for the island of Maui until 9 PM on Saturday as thunderstorms have popped up on the radar.
A Special Marine Warning is in effect for the coastal waters off of windward Oahu and Molokai due to strong thunderstorms.
A Winter Storm Warning is in effect for the island of Hawaii Island until Sunday. Heavy snow on the summits will be possible with total accumulations up to 10 inches expected above 12,000 feet.
The low-pressure area is weaker than last week’s system, but has already produced rainfall that has triggered flash flooding, as rain is falling on already soaked ground. The saturated ground cannot absorb any further rainfall, exacerbating the flooding threat.
Several rounds of moderate to heavy rainfall are anticipated as the kona low develops and draws more abundant moisture over the islands.
The latest forecast data suggests that the highest rainfall totals throughout the weekend will be over Oahu and Maui County.
Hawaii Island and Kauai could still see heavy rainfall, so residents should remain on alert. It will not take much rainfall for flash flooding to occur.
Day-by-day forecast
Saturday: Heavier rainfall will be focused on the central islands of Oahu, and Maui County, with drier air expected over Kauai and less moisture for Hawaii Island. At this point, even moderate rates of rainfall will be enough to trigger flash flooding as the ground is extremely saturated from last week’s storm. The Flood Watch for Kauai has been cancelled due to more stable conditions there.
Heavy rainfall remains possible, mainly for Oahu and Maui County.
Sunday: This band of heavy showers will advance to Hawaii Island on Sunday. Expect higher rainfall totals over windward Hawaii Island throughout Sunday and linger into Monday. Some pop up storms are possible for Oahu and Maui County.
Rain Check: 5-day totals show Kona Low dumped more rain than expected across Hawaii
Anyone recently impacted by flooding is urged to stay alert this week — even if the overall risk is lower.
Five-day rainfall totals from the first Kona storm are posted below.
Here’s a look at some of the highest rainfall totals measured across the state.(HNN Weather)
Winds: Winds will not be as much of a concern with the approaching Kona Low system. Breezy to gusty southerly winds will remain throughout Saturday.
Some gusts could climb between 30 – 45 miles per hour on Saturday. These gusts, of course, will be much weaker than the previous Kona low. However, some downed trees and power lines are still possible due to the extremely saturated ground.
Sustained winds southerly winds between 15 – 25 miles per hour are possible, shifting to be more southwesterly throughout the weekend.
View the latest weather conditions here.
Download the HNN Weather app from the Apple App Store or Google Play for the latest updates from your First Alert Weather Team: chief meteorologist Jennifer Robbins, meteorologist Drew Davis, and weather anchors Guy Hagi, Ben Gutierrez, and Billy V.
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