PartnerRe Ltd expects to sustain losses of between $50 million and $70 million from the outbreak of deadly tornadoes that hit the US in the last week of April.Like many property-catastrophe reinsurers, PartnerRe is having an expensive year. The Bermuda company was hit by catastrophe losses of more than $1 billion in the first quarter alone on its way to a net loss of $807 million in the first three months of the year.The start to 2011 has proved to be a baptism of fire for new chief executive officer Costas Miranthis, who succeeded Patrick Thiele at the end of lat year.Catastrophe modeller Risk Management Solutions (RMS) has estimated the tornadoes, which struck between April 25 and 28 and killed more than 200 people, may cost insurers about $6 billion, with 70 percent of the claims likely to emanate from the state of Alabama, where the town of Tuscaloosa was particularly hard hit.April 28 was the deadliest single 24-hour period for US tornadoes since 1974, according to AccuWeather. About 305 tornadoes touched down during the outbreak, more than twice the April average of 161, RMS saidThe losses do not take into account the tornadoes that caused widespread damage last month, including the EF5 monster which razed a large portion of the Missouri town of Joplin.PartnerRe said the net loss for this event, which will be recorded in the company’s second-quarter 2011 results, will primarily impact the company’s Catastrophe, North America, and Global (Non-US) Specialty sub-segments.Loss estimates are pre-tax, net of retrocession and reinstatement premiums, and relate to all reinsurance contracts and insurance-linked securities expected to be impacted by these events.Last month, Endurance Specialty Holdings Ltd became the first Bermuda re/insurer to post a loss estimate from the April outbreak, ranging from $45 million to $55 million.