Storm updates: Flash flood warnings issued for O‘ahu, Big Island; Ocean Safety urges…

Ongoing rains have prompted a flash flood warning for O‘ahu, which remains in effect until 4:30 p.m.

According to the National Weather Service in Honolulu, at 1:25 p.m. "radar indicated heavy rain over Windward O‘ahu and extending into Mānoa Valley and Pālolo Valley," falling at 2 to 4 inches per hour, with streams in the valleys rising.

A flash flood warning also is in effect for the east side of Hawai‘i Island until 3:45 p.m. Just after 1 p.m., radar showed "an area of very heavy rain" between Laupāhoehoe and Mountain View, falling at a rate of 2 to 4 inches per hour, the warning notes.

A flood watch is in effect for the Big Island through this afternoon.

Find more updates here.

Additionally:

The Honolulu Ocean Safety Department says people should stay out of the ocean after the recent heavy rains.

The state Department of Health issued a Brown Water Advisory for Oʻahu "and recommends that everyone should avoid ocean waters for at least 72 hours after the last rainfall," a Monday announcement from the city notes. "Even beyond that timeframe, the public should continue to avoid entering areas where the water is brown or murky, especially near stream mouths, drainage outlets, and other locations where runoff flows into the ocean."

Here are some key safety reminders:

Avoid brown or murky water, as it may contain bacteria and contaminants that can cause illness or infection.
Be alert for debris in the water, including floating or submerged objects that can cause injury.
Be mindful of marine life activity, as runoff and debris entering the ocean may attract sharks and other marine life.

There currently no beach closures and ocean conditions "may appear calm," the city says.

In a separate announcement Monday, the city also urged the public to refrain from entering storm-affected areas in Waialua and Hale‘iwa unless you're a resident, an authorized worker, emergency personnel or involved in recovery efforts.

"Officials have received reports of individuals traveling into impacted areas to observe damage, creating dangerous conditions and slowing emergency and cleanup operations," the city says. "Storm-affected areas remain active emergency and work zones. Unnecessary travel into these areas is causing traffic congestion and creating safety hazards for emergency responders, repair crews and utility workers working to restore services and stabilize impacted communities."

The Honolulu Police Department also asks drivers to avoid unnecessary travel to Kaukonahua Road and the Otake Camp area in Waialua this week as storm cleanup continues.

"HPD officers are deployed in the area to provide traffic control and security in support of recovery efforts," the city says. "Motorists in the area must follow directions from HPD officers managing traffic and restricting access where necessary."

A second Kona Low storm system — which battered O‘ahu and Maui last week, prompting evacuations and causing damage that could top $1 billion, according to Gov. Josh Green — on Monday continued to "move rapidly towards the northeast away from the state and a high pressure system builds in quickly as the low departs," according to a forecast from the National Weather Service in Honolulu.

"An upper level subtropical jet stream and deep unstable band of tropical moisture lingers over the Big Island today," the forecast notes. "This larger scale moisture band will drift eastward as high pressure builds in from the northwest, allowing more stabilizing trade winds to spread down the island chain. These cooler moderate to locally breezy trade winds will lower humidity levels and continue blowing across the Islands through next weekend with passing showers favoring windward and mountain areas."