A rogue storm system caused Pakistan's floods

Terra Daily: Last summer's disastrous Pakistan floods that killed more than 2,000 people and left more than 20 million injured or homeless were caused by a rogue weather system that wandered hundreds of miles farther west than is normal for such systems, new research shows.

Storm systems that bring widespread, long-lasting rain over eastern India and Bangladesh form over the Bay of Bengal, at the east edge of India, said Robert Houze, a University of Washington atmospheric sciences professor. But Pakistan, on the Arabian Sea west of India, is substantially more arid and its storms typically produce only locally heavy rainfall.

The flooding began in July and at one point it was estimated that 20 percent of Pakistan's total land area was under water. Structural damage was estimated at more than $4 billion, and the World Health Organization estimated that as many as 10 million people had to drink unsafe water.

Houze and colleagues examined radar data from the Tropical Rainfall Measuring Mission satellite and were able to see that the rainfall that caused the Indus River in Pakistan to overflow was triggered over the Himalayas, within a storm system that had formed over the Bay of Bengal in late July and moved unusually far to the west. Because the rain clouds were within the moisture-laden storm from the east, they were able to pour abnormal amounts of rain on the barren mountainsides, which then ran into the Indus….