Weather Post by Dr. Ryan Maue
The Atacama desert in Chile described as the driest place on Earth just got walloped by an extreme cold front (climate change) and was buried in snow.
According to the national emergency centre in Chile, the area had not seen this amount of snow in close to 20 years. Some areas received up to 80 centimeters (32 inches) of snow, leading to closed roads and stuck vehicles. The temperature in Santiago, Chile dropped to as low as -8.5 degrees Celsius on Wednesday. Other countries in Latin America such as Uruguay and Argentina have also been affected by the cold front.
Indeed, temperatures over much of middle-latitudes South America have been averaging 5°-10° C below normal for the past week.
From Wikipedia’s excellent article on the Atacama Desert:
Some parts of Atacama Desert, especially, surroundings of the abandoned Yungay town(in Antofagasta Region, Chile) are arguably the driest places on Earth,and are virtually sterile because they are blocked from moisture on both sides by the Andes mountains and by the Chilean Coast Range. A coastal inversion layer created by the cold Humboldt Current and the anticyclone of the Pacific is essential to keeping the climate of the Atacama dry. The average rainfall in the Chilean region of Antofagasta is just 1 millimetre (0.04 in) per year. Some weather stations in the Atacama have never received rain. Evidence suggests that the Atacama may not have had any significant rainfall from 1570 to 1971. It is so arid that mountains that reach as high as 6,885 metres (22,589 ft) are completely free of glaciers and, in the southern part from 25°S to 27°S, may have been glacier-free throughout the Quaternary, though permafrost extends down to an altitude of 4,400 metres (14,400 ft) and is continuous above 5,600 metres (18,400 ft). Studies by a group of British scientists have suggested that some river beds have been dry for 120,000 years.
In order to get moisture into the desert, it must get into the so-called rainshadow. A possible route is from the NNW, which would require a slug of high-precipitable water or moist air to travel poleward along the South American west coast. Currently, a cut-off low or upper-level potential vorticity anomaly is spinning happily off the Chilean coast — and the clockwise flow (cyclonic in the Southern Hemisphere) is distinctly opposite to the typical anti-cyclone situated in that location. From the most recent week of Precipitable Water animation: all sorts of extreme weather can be found, including Tropical Storm Arlene, it’s landfall and remnants flooding the American Southwest (thunderstorms fueling haboobs), as well as the Atacama snowfall. Click on the image to watch the last week (Java Animation) of precipitable water and low-level wind flow from FSU Maps site.
The July 7, 00Z NCEP GFS global model forecast has additional snowfall for Chile during the next week: Image Link…