WASHINGTON, United States (AFP) — Hurricane Irma could be the costliest storm ever to form in the Atlantic Ocean as it is on track to blast through some of the most expensive properties in Florida, a disaster analyst said Thursday.

Economic damage and losses for all locations hit by Irma could total US$120 billion, if current projections for the storm’s path hold true, according to a disaster modelling firm tracking its progress.

Chuck Watson of Enki Research told AFP that with the storm bearing down like a buzz saw on the Miami, West Palm Beach and Ft. Lauderdale — the richest areas of Florida — Irma could cause about US$100 billion in damage in the US alone.

“It’s a very scary number,” said Watson, whose estimates were varying by the hour.

“If you add everything in, it could be the most expensive Atlantic storm in history.”

In the US, the damage would far surpass the US$78 billion estimate for the devastation from Hurricane Harvey in Texas, and fall just behind Katrina’s US$118 billion cost.

The massive storm also could be a catastrophe for insurers, costing them “the equivalent of 20 years of premiums,” he said.

Watson said his damage estimates were subject to a high degree of uncertainty and a slight variation in the storm’s path could cut the amount in half.

But current path projected by the National Hurricane Center points to maximum damage.

“This was always the nightmare scenario of a Category Four or Five storm running right up that corridor,” he said. “There’s just so much high value property sitting right there on the ocean, practically.”

“It’s just a big fat target.”

Public and commercial insurance providers are still responding to Harvey, which ravaged the Houston area with torrential rain and floods at the end of August. However, flood damage is not generally covered by insurance.

Unlike Harvey, Irma was likely to cause most of its damage through wind, waves and storm surge and not flooding — meaning private insurers will face far higher liabilities than they did in Houston.

“Harvey was not a big problem for the private insurance industry but Irma is going to be a catastrophe for the private insurance industry,” Watson said.

– 1.2 million people ‘battered’ –

An estimated 1.2 million people have already been “battered” by Irma, a number that could surge to 26 million, the Red Cross said Thursday.

“Our worst fears have played out in Barbuda and elsewhere,” Walter Cotte, Americas director for the International Federation of Red Cross and Red Crescent Societies (IFRC), said in a statement.

Irma — one of the most powerful Atlantic storms on record — has turned the Caribbean islands of Barbuda and St Martin into mountains of rubble.

The Geneva-based IFRC said that Irma “may have already battered an estimated 1.2 million people and poses a serious threat to millions more”.

The organisation specified that in the Dominican Republic, Haiti and Cuba “an estimated 26 million people could be exposed to destructive winds and torrential rain.”

An initial 600,000 Swiss francs (US$631,000 / 525,000 euros) in emergency funds have been released to help preparedness efforts in the Dominican Republic and Haiti, the Red Cross said.

“People across the Caribbean will need our help to withstand and then recover from this storm,” Cotte said. “We’re already preparing what could become a massive and multi-country response effort.”

Irma was packing maximum sustained winds of up to 185 mph (295 kph) as it followed a projected path that would see it hit the northern edges of the Dominican Republic and Haiti on Thursday, continuing past eastern Cuba before veering north for Florida.