ANAHOLA, Kauai — As if COVID-19 wasn’t enough of a challenge, a violent storm system that started dumping rain early Monday morning rattled Kauai with two severe thunderstorm warnings and an unprecedented tornado warning.

By early Tuesday afternoon, the storm, which consisted of almost uninterrupted heavy rain for more than 36 hours on the North Shore, had left Hanalei and the rest of the west end of the island cut off by flooding that closed Kuhio Highway.

Although the Hanalei River floods the roadway several times in the average year, this week’s disruption was reminiscent of the major rain and flooding event of April 2018, which shut down the highway for nearly a year.

Extremely heavy rain, thunder and lightning rattled the island for several hours overnight from Monday to Tuesday. The mayhem led the National Weather Service to issue two separate severe thunderstorm warnings, a flash flood warning and then a tornado warning in the early hours of Tuesday.

“Do not cross fast-flowing or rising water in your vehicle or on foot,” the Weather Service said. “Ponding, low visibility and other hazardous driving conditions are expected.”

There were no reports of a tornado actually forming on Kauai — at least as of early Tuesday afternoon — but about 1:30 a.m., the weather service said a severe thunder storm about 28 miles southwest of Barking Sands was moving toward the island at about 30 miles per hour and had the energy intensity capacity to unleash a twister.

The storm roared ashore and drove more than three hours of intense rainfall, accompanied by thunder and lightning. At the height of the electrical storm, the worst of the rain was reported in the Kalaheo area, but Kilauea on the North Shore also experienced extreme storm conditions.

By early afternoon, Kuhio Highway west of Hanalei had not sustained the severe damage it did in April 2018, but the Hanalei River overflowed its banks and flooded hundreds of acres of low-lying land.

About 45 people were reported hunkered down in an emergency shelter at the Hanalei School and, by Tuesday morning, pleas were being circulated on Facebook for anyone in the area who could do so to deliver hot food to the dozens who were stranded. The Red Cross was operating the shelter.

The Anahola Stream, which had seen heavy flooding two years ago, overflowed again, though there were no reports of houses being inundated. Many homes along the river have been built on stilts — a property that clearly prevented flooding.

The Kauai Police Department’s Facebook page offered this advice Tuesday afternoon: “While the major roads, besides Hanalei, are currently open, flooding and heavy ponding is still occurring in many areas of the island and could happen on any road at a moment’s notice.”

Earlier, there were full or partial highway closures in Wailua and Hanapepe.

County and state crews worked to clear small slides that blocked several local streets. Heavy equipment was brought in to clear the worst of the slides, including one in Moloaa.

By 8 a.m. Tuesday, more than 14 inches of rain had fallen in Kilauea, according to postings by volunteers for the Community Collaborative Rain, Hail and Snow Network, which is based in Colorado. CoCoRaHS volunteers reported more than 13 inches of rain in some parts of Kapaa, nearly 8 inches in Anahola, more than 7 inches in Lihue and nearly 7 inches in Koloa between midnight Monday and 8 a.m. Tuesday. Rainfall reports for Hanalei were not immediately available Tuesday.

As is sometimes the case during this time of year, the Kauai rainfall totals dwarfed those reported on other islands. About 3.7 inches of rain had fallen in the same period in Kaneohe and nearly two inches in Honolulu, where the Weather Service issued a severe thunderstorm warning late Tuesday morning.

Pahoa on Hawaii Island reported less than a half inch, while Maunaloa on Maui recorded just under 2 inches.