Blog Archive

Saturday, March 28, 2015

14 years' worth of rain in Chile's Atacama desert

from Jeff Masters' Wunderground blog, March 27, 2015

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 a.m. EDT, March 26. That's over 14 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. 

Video 1. Raging flood waters sweep through one of the driest places on Earth, Chile’s Atacama Desert, on March 25, 2015, after fourteen years’ worth of rain (0.96”) fell in one day. Thanks go to wunderground member Chris Hamburg for posting this link in my blog comments.

No comments: