The Red Cross said Wednesday the death toll in Myanmar's cyclone may be between 68,833 and 127,990. The International Federation of Red Cross and Red Crescent Societies said it arrived at the figure by pooling and extrapolating assessments by other aid groups and organizations. It said in a situation report on Myanmar that the total affected population is between 1.64 million and 2.51 million. The report issued Wednesday noted that "official government casualty figures remain significantly lower." The government said 34,273 people were killed and 27,838 were missing in the May 2-3 Cyclone Nargis. The Red Cross figure is the highest reported so far. The UN has said the number of dead could be between 60,000 and 100,000. Heavy rains and another powerful storm are posing a serious threat to relief operations in Myanmar's cyclone-devastated delta, where so little aid has reached that the UN warned Wednesday of a possible "second wave of deaths" among an estimated 2 million survivors. The US military's Joint Typhoon Warning Center said there is a good chance "a significant tropical cyclone" will form within a day and head across the Irrawaddy delta, though other forecasters were unwilling to make such a prediction. Rain has been pounding the cyclone-hit area all week, and more is expected in the coming days. The weather is compounding the already difficult task of moving aid supplies over ruined roads. It also poses significant health risks to survivors of the original May 3 storm. "The weather will exacerbate humanitarian conditions for the homeless, many of whom are living under an open sky," said Elizabeth Griffin, a director of US-based Catholic Relief Services. "Thankfully, no serious outbreaks of bacterial, water- or mosquito-borne diseases have been reported, but this could change in the next two to three weeks."