The apparent deaths of a Häna couple believed to have been swept away while crossing an East Maui streambed on Thanksgiving night are a grim reminder of the potentially deadly force behind Hawai'i's swift and sudden flash floods.

At least a dozen other people have died in flash flood-related incidents in Hawai'i since 2000. The victims include the seven people on Kaua'i killed in the Kaloko Dam disaster of March 2006, and a Louisville, Ky., man and his 8-year-old daughter, who were caught in a 6-foot wall of stream water at Haleakalä National Park in Kípahulu and were swept over a 184-foot waterfall and out to sea in April 2003.

Maui officials said Häna residents Carl and Rae Lindquist, both 75, likely perished on their drive home after enjoying Thanksgiving dinner at the Hotel Häna-Maui. Their battered 2004 Ford sport utility vehicle was found Saturday about 200 yards downstream from 'Ula'ino Road.

Maui Fire Department officials said water levels in the stream reached 12 feet or higher on Thanksgiving, when Häna was hit with 2 inches of rain in an hour.

Fire officials yesterday called off the search for the Lindquists, who were active in community affairs and owned Hana Coast Realty. Häna resident Dawn Lono said community members will continue the search on their own today.

The circumstances of the Häna incident are similar to a January 2002 flash-flood event that claimed the lives of three people in Central Maui. The victims were riding in a Jeep Cherokee that was flipped by floodwaters in Kope Gulch in Upper Waiehu.

A survivor at the time said the four-wheel-drive vehicle gave the group a false sense of security that they could drive safely over a concrete stream crossing even though rushing water had nearly engulfed two sedans before them.

Crossing a streambed or road covered with fast-moving water is never a good idea, no matter how familiar you are with the terrain, said public safety officials. Just 6 inches of flowing water can knock someone off their feet and 2 feet of water will carry away most automobiles, according to the National Weather Service's "Turn Around, Don't Drown" public awareness campaign.

Data from the service's Honolulu office show most flash-flood deaths in Hawai'i happen when people cross or fall into fast-rushing streams or try to drive across flooded roads or gullies, or when homes and other structures are inundated.

'NO CONTROL'

Since 1960, there have been 53 flash flood-related deaths in Hawai'i, although records are incomplete because they rely on reports from other agencies, said Ray Tanabe, warning coordination meteorologist with the weather service.

The records do not include the 2002 Waiehu fatalities or the March 1994 deaths of a Maui mother and her 4-year-old son, who were swept from their vehicle while attempting to cross flooded Kaua'ula Stream in Lahaina, just 75 yards from their house.

Maui Fire Battalion Chief Jeff Shaffer said many people underestimate the power of floodwaters.

"It might look like 6 inches but the road might have washed out and it's really 18 or 24 inches, and once you lose traction and those wheels get off the ground, there's no control," Shaffer said.

He advised using common sense "and erring on the side of safety" by turning around when confronted with flooded roads, or not going out in the first place when likely to encounter flash-flood conditions.

National Weather Service data show that flash floods can occur during any month of the year, but are most frequent during Hawai'i's wet season, which runs from October through April. October and November are the months with the most flash-flood events.

The Islands' steep topography and miles-long stream systems provide an efficient pipeline to send large volumes of rainwater from mountaintops downstream to sea level at high speed.

For those at lower elevations, there often is little warning.

"From the time heavy rains start, you could see flash flooding in minutes, especially on the eastern side of Maui where there are a lot of deep gullies that focus a lot of the rainfall into small areas," Tanabe said.

"Hawai'i also has a lot of roads that cross streams with culverts underneath, and they can become plugged with tree branches, rocks and other debris. Any time you reduce the capacity of culverts, water goes over the road, and once water goes over the road, typically it's filled with debris and the water is dirty, and you can't tell how deep the water is, and it doesn't take much," he said.

"If you're driving at night on an unlit section of roadway, you're not going to be able to tell the depth of the water. Some people with SUVs think they're safe because they have a bigger, heavier vehicle. That's not a good assumption."

Tanabe advises checking the weather forecast before venturing out into flood-prone areas and monitoring weather conditions. It may be sunny on the coast, but a flash flood could be brewing in the mountains, he said.

"You really have to be aware of what's going on," Tanabe said. "If you hear thunder or there are heavy rains or the streams start to rise even a little bit, these are natural signals of a flash flood."