Atacama Desert - World's Driest - Gets 14 Years' Worth Of Rain In One Day - Wunderground
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Amazing rains in the Chilean desert
Unwelcome rains fell this week in Earth's driest place--Chile's Atacama Desert--causing destructive flooding that has left seven people dead and at nineteen others missing. Antofagasta, which averaged just 3.8 mm of precipitation per year between 1970 - 2000, and has a long-term average of 1.7 mm of precipitation per year, received a deluge of 24.4 mm (0.96 inches) during the 24 hour period ending at 8 am EDT March 26. That's over fourteen years of rain in one day! The rains were due to an unusually strong and persistent "cut-off" low pressure system that was trapped over Chile by the exceptionally strong ridge of high pressure that brought the warmest temperatures on record to Antarctica early in the week. A cold front associated with the cut-off low hit the Andes Mountains, dumping rains over soils with very little vegetation (due to the dry climate.) Unusually warm ocean temperatures approximately 1°C (1.8°F) above average off of the coast meant that high amounts of water vapor were available to fuel the storm and generate exceptionally heavy rains. Heavy precipitation events are common in Chile during El Niño events, like we are experiencing now. El Niño brings warmer than average waters to the Pacific coast of South America where Chile lies.
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http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2944