Freak Snow Whitens Desert

A series of freak heavy snowfalls earlier this month left a swath of South American desert smothered in a deep mantle of snow.

The instigating storms targeted the Atacama Desert, including its share of the western Andes from northern Chile into neighboring Bolivia and northwestern Argentina.

At low elevation, rainfall varied widely and was locally heavy, even causing flooding.

In some spots, such as Arica, Chile, a modest fall of rain was enough to equal multiple years of normal rainfall. Area average yearly rainfall is as low as 1 to 3 mm (about 4/100 to 12/100 of an inch), according to NASA's Earth Observatory.

However, at high elevation, mostly above 12,000 feet, snowfall was uniformly heavy in a stretch of the western Andes, straddling the borders of Bolivia and northwestern Argentina with northern Chile.

Media reports at the time, widely attributed to the BBC, told of snowfall up to 80 cm (32 inches).

Although "official" snowfall data are not readily available, a look at high-resolution visible satellite imagery, taken by NASA on July 7, shows bright, white landscape that would seem to confirm the ground reports.

The close-up satellite image, grabbed from a much larger NASA image, shows desert mountains of far-northern Chile into westernmost Bolivia. At the southern end of the image is the area of Calama and Chuquicamata, which had significant rain, but not snow.

GOES-12/SMN-Argentina image, taken July 15, shows rare desert snow lingering in Chile.

Farther north and east, snow cover is obvious. A look at topographic maps shows that the line of significant snow cover, at the time the image was taken, was near the 12,000-foot level.

What little precipitation that does fall in this desert reach of the Andes normally happens during the Southern summer, or December through February; winter gets virtually no precipitation.

Storm impact including flooding was serious enough to necessitate evacuations in the Chilean desert lowland. Higher up, rain and snow both disrupted transportation, especially through cross-border passes. Media reports told of a number of people being stranded, then rescued, in the cold when snow made roads impassable.

Mining, a huge money-maker in this part of the world, was also negatively affected. Two of the world's three biggest copper mines were hit by snow, which disrupted operations. Lost output was reportedly in the thousands of tons of copper metal.

One of the mines, La Escondida, is located within the snow-covered area above (north of) Calama on the satellite close-up.

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