Snow in Atacama desert in Chile

[Michael]

http://www.irishweatheronline.com/news/ ... 25330.html

[RWood]

Interesting report, but it inevitably oversimplifies things. The snow fell at high elevations where the hyperdesert category is not applicable.

Meteo Chile has information (in Spanish) on Atacama climates (note the plural). For the northernmost 3 regions that constitute the desert, 4 different zones, divided by elevation and distance from the coast, are described. Only the 2 lower zones are true hyperdesert - the coastal type is exemplified by Arica (0.7mm annual rainfall), Iquique (similar) and Antofagasta (1.7mm). Calama at 2000m + ASL is in an inland category, still hyperdry with 5.7mm as its 30-year average.

As far as I can tell the snow events occurred in the highest zone near the Chile/Bolivian border, where mean rainfall in the north can exceed 400mm, though it decreases to under 100mm or even 50mm further south before increasing again in higher latitudes. The norhern zone rainfall normally comes from summer showers and overspill.

Looking at MeteoChile data, the max/min for Calama and Arica for the last couple of days seem to be fairly normal.

The claims about dryness are exaggerated in the sense that there is no recording station of significance that hasn't recorded rain, to my knowledge. Quillaga in the Antofagasta region had a 30-year average of under 0.5mm I think, and that probably hasn't been beaten. Any place claiming to never have seen rain needs to install a recorder and wait several decades at least.

I have a strong interest in this area, having once spent a while there on holiday in Chile and Bolivia.

[RWood]

The talk of the South American cold snap ignores (as in 2007) the normal or hotter than normal conditions prevailing further north and east in Brazil:

Federal district: http://weather.yahoo.com/brazil/distrit ... ia-455819/

Salvador de Bahia: http://weather.yahoo.com/brazil/bahia/salvador-455826/

Teresina (well known hotspot): http://weather.yahoo.com/brazil/piaui/teresina-455835/

[Richard]

The information that you have posted Rupert is so informative,thank you
Even so,taking into account the minimal annual rainfall rates of the 4 different zones,80cm is still a huge amount in a single event,

[RWood]

The information that you have posted Rupert is so informative,thank you
Even so,taking into account the minimal annual rainfall rates of the 4 different zones,80cm is still a huge amount in a single event,

Yes, more than they're used to. It does however annoy me that cold spell reports (eg for South America) are always taken in isolation, and give a distorted impression. From Australian reports, you'd think the SH had a cold June overall - it didn't.