Flash Floods Close Kuhio Highway Near Hanalei Bridge, Reopen Later

Heavy rainfall triggered flash flooding near Princeville on Kauai, prompting police to shut down Kuhio Highway near the Hanalei River Bridge early Saturday, and prompting flash flood warnings for Kauai and Oahu from the National Weather Service. Hawaii DOT later reported the road was partially reopened and then fully reopened later in the day.

The NWS issued its initial flash flood warning around 3 a.m., and Hawaii News Now published an early update at 5:58 a.m. HST. Radar showed intense early-morning rainfall over windward Kauai; at 3:49 a.m. radar indicated rain falling at a rate of 2 to 3 inches per hour in the heaviest showers. Hawaii News Now recorded later morning extensions of warnings, an Oahu warning extended as of 8:13 a.m. to 1:13 p.m., and a Kauai warning extended as of 8:41 a.m. to 12:11 p.m.

Kauai Emergency Management reported the Princeville side of Kuhio Highway closed near the Hanalei River Bridge because of water over the roadway. KITV noted that "Water levels along the Hanalei River are high enough that Kuhio Highway near the Hanalei River Bridge has been closed," and said flooding affected low-lying areas, streams, and roads with additional heavy showers expected to move onshore in the morning. KITV also relayed safety messaging: "Residents are urged to stay away from streams, rivers, and drainage ditches, even if they appear calm." and "Drivers and pedestrians should never attempt to cross flooded roads."

Morning communications from the NWS and local media warned of fast-rising runoff and possible mudslides in saturated steep areas. KITV printed an NWS observation: "At 1010 AM HST, radar and automated rain gauges indicate heavy rain falling over the Koolau Mountains..." and noted that on Oahu rain rates were 2 to 4 inches per hour with pockets over 6 inches per hour in places such as Luluku. On Oahu the Likelike Highway off-ramp from H-3 Kaneohe-bound was reported closed and stream gauges showed sharp rises in multiple waterways.

State traffic notices show routine February work on Kuhio Highway as well, distinct from the storm closure. HIDOT bulletins list a full Princeville nighttime closure of Kuhio Highway between mile post 0.3 and 1.2 for paving on February 9 to 12 from 11 p.m. to 5 a.m., and single-lane tree-trimming closures between mile post 0.7 and 1.2 on February 9. A Lihue center lane closure between mile post 0.1 and 0.3 for waterline replacement is also on HIDOT schedules.

As context for what heavy north shore flooding can do, a separate Weather account of a past intense episode on April 14–15 documented rainfall rates of 5 to 7+ inches per hour at the peak and noted flash flooding that placed portions of Kuhio Highway near the Hanalei Bridge under 5 to 8 feet of water, with landslides and washouts reported in Wainiha and Kalihiwai Valley. That severe episode is a precedent and not a direct description of Saturday morning’s event.

The NWS flood watch language remained stark: "FLOOD WATCH IN EFFECT FOR NIIHAU KAUAI AND OAHU THROUGH THIS AFTERNOON FOR KAUAI COUNTY AND OAHU... WHAT...Flash flooding caused by excessive rainfall continues to be possible." Authorities emphasized life-safety guidance, including "Do not cross fast flowing or rising water in your vehicle, or on foot. Turn around, don`t drown." and advised residents to monitor forecasts as the upper-level trough that produced periods of heavy showers is expected to lift north later this afternoon, which should diminish the flooding threat.