Recent Hurricane Irene estimates put U.S. insured losses between$1.6 billion and $6.6 billion.

Shortly after Hurricane Irene, Eqecat released a U.S.insured-loss estimate of between $1.5 billion and $2.8 billion,while AIR Worldwide put the range of U.S. insured losses at $3billion to $6 billion.

Risk Management Solutions (RMS) decided to hold off on anestimate immediately after the storm, but the modeler now reportsthat it expects U.S. losses to be between $2 billion and $4.5billion. Adding in Caribbean losses, the estimate is between $2.5billion and $5.5 billion.

Aon Benfield's catastrophe-modeldevelopment center, Impact Forecasting, estimates U.S. insuredlosses from Hurricane Irene of between $1.6 billion and $6.6billion.

For RMS, Michael Kistler, director of model solutions, says,“Our estimate range reflects some uncertainty, including thedefinition of hurricane vs. non-hurricane deductibles forindividual states, and the uncertainty surrounding losses fromdamage caused by tropical-storm winds. During Irene, a large swathof tropical-force and low-hurricane-force winds swept across alarge area of exposure causing widespread, low levels ofdamage.”

Meanwhile, Eqecat released more information on how it arrived atits estimate, and the firm offered estimated  losses forthe National Flood Insurance Program (NFIP). The modeler notes thatlow-hurricane-force winds and heavy rainfall “contributesignificant uncertainty to the ultimate levels of insurancepayouts; a five-knot increase in modeled wind speeds would doublethe estimated losses from this event and a five-knot decrease wouldcut this estimate in half. A 10 percent increase in damage rates toproperties from heavy rains would cause a 15 percent increase inthe loss estimate.”

While Irene caused “significant billions of dollars of damagefrom winds and rain,” says Eqecat, the primary driver of damage wasfrom rainfall-induced flooding.

The heavy rains cause some uncertainties in hurricane-damageestimation, Eqecat notes, “including the additional damagingeffects of an exceptionally wet event and uncertainties around howflood and wind and rain damages are separated for insurance-losspayments.”

Eqecat says most of the damage from Irene was caused byextensive flooding, and most of this is expected to be uninsured.The largest flood insurer is the NFIP, and Eqecat says U.S.historical trends in NFIP data indicate that losses should notapproach the levels reached from recent Gulf of Mexico hurricanes,and likely will be less than $1 billion.

By contrast, Hurricane Katrina resulted in $16 billion inflood-program losses; Hurricane Ike resulted in $2.6 billion; andHurricane Ivan resulted in $1.6 billion.

More than 3.4 million NFIP policies are in the Gulf coastalstates, while the East Coast and Northeast have a lowerconcentration of policies.

Eqecat says that, as of 2010, there were 136,000 flood policiesin North Carolina, 230,000 in New Jersey, 160,000 in New York,40,000 in Connecticut, 15,000 in Rhode Island, 25,000 in Delawareand 70,000 in Maryland.

Eqecat excludes potential insured losses to the NFIP from itsinsured-loss estimate for Irene.