Raindrops collect on a car window in Kahului in 2018. Maui County is preparing for the arrival of a kona low later this week, with flash flooding and runoff from fire-burned areas the primary concerns, a weather official said. The Maui News / MATTHEW THAYER photo
Maui County is actively inspecting and clearing South Maui and Upcountry culverts and already has a pollutant filter system in Lahaina to deal with stormwater runoff as it prepares for this week’s kona low with possible flash flooding and thunderstorms, officials said Monday.
The National Weather Service said rains from the kona low will begin affecting Kauai and Oahu today, followed by the rest of the island chain later this week.
A flood watch was issued for Kauai and Oahu Monday and will likely be expanded to include Maui County and Hawaii island for Wednesday and Thursday, National Weather Service Forecaster Tina Stall said in an email Monday.
“This rainfall will certainly help the drought situation on Maui, though the exact extent to which it would be relieved can’t be quantified at this time,” Stall said. “Right now, the biggest concern state-wide and especially over the recent burn areas is for flash flooding and potentially significant water runoff.”
In a news release Monday, the county said it has partnered with the state and local contractors to protect storm drain and waterway inlets in Lahaina with a pollutant filter system called Envirosoxx, which was installed in August.
A screenshot of the National Weather Service’s radar map shows the Hawaiian islands under a small craft advisory and flood watch in certain areas as a kona low approaches the state, potentially bringing rain and flooding. National Weather Service graphic
The “cutting-edge” filtration system is designed to capture, reduce and filter pollutants from stormwater, runoff which will safeguard coastal waters along Lahaina shorelines, according to the county Department of Public Works.
Flood-mitigating equipment will be staged once the weather service issues information on Maui County locations that could be impacted by the storm.
Employees on each island in the county are preparing their district, public works officials said.
Wind impacts are not anticipated for this weather event, the county added.
Maui County’s Emergency Operations Center remains in a ready state and will move to partial activation for the storm if the weather service issues a flood watch.
As for where exactly the rain will hit on Maui, Stall said: “At this point, it’s hard to say which specific areas of each island will get the highest rainfall totals, but typically the best potential for heavy rainfall in a kona low event would be along the south facing areas of each islands.”
She said Lahaina could see rain Wednesday night and Thursday.
Shower coverage is expected through Friday and into the weekend.
At times kona low weather events have been as damaging as named storms such as hurricanes. One such kona low in December 2021 flooded gulches Upcountry and knocked out water and power for thousands of Maui customers.
Even though the rain earlier this month and expected this week could give Upcountry some relief from dry conditions, Maui County Water Supply Director John Stufflebean said the Upcountry area will remain under a Stage 2 water shortage declaration, which asks customers not to use water for irrigation, washing vehicles or nonessential activities.
“We are staying at Stage 2 due to predictions for a dry winter,” said Stufflebean on Monday.
A Stage 2 water shortage is when anticipated water demand in an area is projected to exceed available water supply by 16 to 30 percent. The declaration took effect Nov. 8 and covers Makawao, upper and lower Kula, Pukalani, Kokomo, Kaupakalua, Ulumalu, Ulupalakua and Kanaio. The Stage 1 declaration for the same areas went into effect Oct. 26.
There has been some rain this month on Maui, which Stufflebean said has added to the reservoirs Upcountry.
He said that water demand in the Upcountry area is now down about 20 percent since earlier this month when the Stage 2 declaration was issued, “so we are OK for now.”
As of last week, the U.S. Drought Monitor indicated “extreme drought,” for West, Central and South Maui areas, which include Lahaina, Maalaea, Kahului, Wailuku, Kihei and Wailea. Other areas were in “severe drought,” which is one step down from extreme, while in East Maui there is “moderate drought,” which is just below severe.
With the kona low approaching, the county encouraged the public to stay informed through credible sources such as the National Weather Service, the Hawai’i Emergency Management Agency and the Maui Emergency Management Agency. To sign up for Maui Police Department road closure notifications, visit bit.ly/MauiRoadClosure.
The county also urged the public to take the necessary steps to be prepared, including having an emergency kit with essential items.
For more information on emergency preparedness, and to sign up for alerts from MEMA, visit www.mauicounty.gov/MEMA.
* Staff Writer Melissa Tanji can be reached at mtanji@mauinews.com.
Raindrops collect on a car window in Kahului in 2018. Maui County is preparing for the arrival of a kona low later this week, with flash flooding and runoff from fire-burned areas the primary concerns, a weather official said. The Maui News / MATTHEW THAYER photo 
A screenshot of the National Weather Service’s radar map shows the Hawaiian islands under a small craft advisory and flood watch in certain areas as a kona low approaches the state, potentially bringing rain and flooding. National Weather Service graphicToday's breaking news and more in your inbox
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