NU Online News Service, June 6, 11:41 a.m.EDT

Thunderstorms in the U.S. that struck from May 20 to May 27 areexpected to cause between $4 billion and $7 billion in insuredlosses, according to catastrophe modeler AIR Worldwide.

AIR says the losses reflect insured physical damage toresidential, commercial and industrial properties—both structuresand contents; automobiles; additional living expenses forresidential claims; business-interruption losses; and effects ofdemand surge. The estimate does not reflect “non-modeled losses,including loss-adjustment expenses,” the cat modeler adds.

“The month of May, normally the most active month for tornadoes,began quietly,” says Tim Doggett, principal scientist at AIRWorldwide, in a statement. “For three weeks, only a handful ofisolated tornadoes were reported. But on May 20, severethunderstorms in eastern Texas and parts of Arkansas and Oklahomabrought high winds, hail and five reported tornadoes. Over the nextseven days, more than 150 confirmed tornadoes raged across theheart of the country.”

He says the severe weather “funneled across a corridor thatstretched from Lake Superior to central Texas and east throughMissouri, Tennessee, Kentucky, Ohio and to the East Coast,impacting more than 20 states in all.”

Doggett states that the individual meteorological elements thatcaused the tornadoes are not unusual. “Large, strong jet streamdisturbances happen occasionally; persistent low-pressure frontalsystems are common, especially in spring. And the storms thatdeveloped occurred where they are expected to occur at this time ofyear.”

However, he adds, “What is unusual is for all of the factorsthat contribute to the development of severe thunderstorms to havealigned themselves so optimally in the same place at an opportunetime. To get optimal intense instability, shear and lift all in thesame place for a long period of time is a relatively rarecircumstance.”

AIR says Missouri was most severely hit from May 20 to May 27.Damage to the state includes the May 22 tornado strike inJoplin.

Kansas saw 14 tornadoes touch down on May 21 alone, with thecity of Reading hit the hardest. Texas, Indiana and Minnesota werealso impacted by the storms.

Meanwhile, Pembroke, Bermuda-based reinsurer Partner Re Ltd.says it expects losses related to the tornado outbreak in April tobe approximately $50-$70 million

Partner Re says the net loss for this event, which will berecorded in the company's second-quarter 2011 results, willprimarily impact the company's catastrophe, North America andglobal (Non-U.S.) specialty subsegments.

Loss estimates are pre-tax, net of retrocession andreinstatement premiums, and relate to all reinsurance contracts andinsurance-linked securities expected to be impacted by theseevents, Partner Re adds.

In late May, catastrophe modeler Risk Management Solutions saidlosses from the April storms will likely be in the range of$3.5 billion to $6 billion.