Total economic losses from Tropical Storm Harvey could be as high as $70-90 billion, with the bulk of the losses coming from inland flooding in the Houston metropolitan area, risk modelling firm RMS said on Wednesday.

The majority of these losses will be uninsured, given private flood insurance is limited, RMS said in a preliminary estimate.

"With the rain still falling heavily and the waters rising, the situation is too fast-moving to be stating with certainty what the losses in Texas could be," Michael Young, RMS head of Americas climate risk modelling, said as quoted by Reuters.

RMS would issue an official insurance loss estimate for the storm "in the coming weeks", Young added.

RMS said last week that wind damage from Harvey would likely lead to insurance losses below $6 billion.

Modelling firm Air Worldwide said earlier this week the insured losses from Harvey's wind and storm surge were estimated at between $1.2 billon and $2.3 billion. That figure does not include flooding.

Analytics firm Corelogic earlier on Wednesday raised its estimate for wind and storm surge insured property losses, excluding flooding, to $1.5-3 billion from $1-2 billion.

Wall Street analysts have forecast insured losses for the storm of as much as $20 billion.