‘CATASTROPHIC FLOODING … : EVACUATE NOW,” Honolulu emergency officials declared last Tuesday afternoon. “You are in danger. Leave now.”

It was the opening act in a week’s worth of dangerous rain and thunderstorms that roared up and down the state.

AccuWeather reported last week that “some areas received up to nearly half a month’s worth of rain in a single day.”

The Associated Press quoted state Board of Land and Natural Resources Chairwoman Suzanne Case on the disaster.

“We have a flood emergency because of the heavy rain bomb. And we’re seeing these more and more across the island chain — more frequent and more extreme events,” she said.

University of Hawaii’s Charles “Chip” Fletcher, associate dean for academic affairs and professor in the Department of Earth Sciences at the School of Ocean and Earth Science, said in an interview that the rain signals bad news.

Hawaii’s future will include lots more rain, Fletcher explained. “It will be more frequent, of greater magnitude, occurring in unexpected locations, and lead to unexpected outcomes,” said Fletcher, one of UH’s top global warming experts.

He says we now need an expanded vocabulary, a new way of talking about the weather.

Basing the talk “on historical patterns is not a scientifically sound basis to protect our communities,” Fletcher said.

No more talking about 100-year storms; things have changed.

“Now is the time, with a climate-akamai administration in Washington, D.C., for local agencies, institutions and stakeholders with responsibility for managing weather-related vulnerabilities — drought, flooding, slope failure, coastal erosion, hurricanes, and importantly heat — to break out of siloed modes of operation,” he said.

That means it is time for the folks who study erosion, flooding or drought to combine forces to develop a plan incorporating all the disciplines.

“Develop an integrated roadmap to a safer future,” Fletcher urged.

Fletcher’s advice would be easily understood by Honolulu’s new mayor, Rick Blangiardi, who last week joined Gov. David Ige on a tour of some of Oahu’s flooded areas. Besides inundated streets and at least six homes under water, Blangiardi has had to contend with an overflowing sewer system.

“We need to get used to climate events like this,” Blangiardi said in an AP report. “A tremendous concentration of rain in a small amount of time in focused areas is going to result in flooding anywhere.”

It is a new global-warming future — where flash flood watches and alerts, besides becoming common, remain a devastating predictor of bad times to come.

Richard Borreca writes on politics on Sundays. Reach him at 808onpolitics@gmail.com.