HONOLULU -- The National Weather Service placed Kauai, Oahu and Molokai under several weather alerts on Tuesday as heavy rains moved through the state.

Forecasters issued a flash flood watch for Oahu, Kauai and Molokai until Wednesday morning. The NWS also issued a severe thunderstorm watch for Kauai and Oahu.

Heavy rains flooded homes and farms on Kauai on Monday and shut down the only road into and out of Hanalei.

People who live in Hanalei said it's the worst flooding they've seen there in more than five years. The wettest spot on the island got about 18 inches of rain in a 24-hour period.

Hanalei Valley was covered with floodwaters. There were only a few spots where some of the taro grown there was still visible.

At mid-afternoon on Tuesday, the 24-hour rainfall total for Hanalei River was 8 inches and Mount Waialeale above it, the wettest spot in the world, recorded more than 18 inches of rain in the last day.

Hanalei taro farmers said the floods will stunt their crops, meaning a smaller harvest.

"It's going to go down -- the yield. As far as how much, I cannot say. I cannot say how much it's going to affect the market; the supply of taro for poi," farmer Rodney Haraguchi said.

"After a flood, maybe a few days later, you look at the leaves. They look like they're all burned because they don't have any oxygen. They're underwater. They're drowning," farmer Christine Kobayashi said.

Police blocked access to the Hanalei Bridge because the highway flooded nearby.

"(That) strands all of the Hanalei community, about 4,500 people up in that community, that rely on the one roadway to come out of there," said Mark Marshall of the Kauai Civil Defense.

Hanalei Elementary School never opened on Tuesday. Up the road, traffic on Kalihiwai Bridge was reduced to one lane.

"Driving through Kalihiwai was particularly treacherous. They have landslides and boulders on the road," Princeville resident Jaana Makipaa said.

A gushing waterfall occasionally brought down big pieces of debris just a few feet away from traffic. Police closed the lane closest to the waterfall.

On the south side of the island, two or three homes were flooded near Koloa, when a dike broke along Waikumu Stream. Civil Defense officials said the families did not evacuate.

Here are some 24-hour rainfall totals for the period ending at 11 a.m. Tuesday (in inches):
Kauai:

Mount Waialeale 17.97

Hanalei River 8.16

Hanalei 4.86

Wailua 3.86

Kalaheo 3.83

Kapahi 2.06

Lihue Variety Station 1.74

Oahu:

Wilson Tunnel 7.06

Luluku 4.25

Waihee Pump 3.16

Ahuimanu Loop 3.05

Manoa 2.45

Maunawili 2.09

St. Stephens 1.75

Nuuanu Upper 1.59

Maui:

West Wailua Iki Stream 4.29

Big Island:

Waiakea Uka 4.15

Mountain View 3.18

Laupahoehoe 2.23

Pahoa 2.20

Hilo Airport 2.13

Glenwood 1.35