Heat intensifies Siberian wildfires

The summer of 2012 was the most severe wildfire season Russia had faced in a decade. 2013 might be headed in the same direction after an unusual heat wave brought a surge of fire activity in northern Siberia in July.

A persistent high-pressure weather pattern in the Russian Arctic—a blocking high—contributed to the heat wave, which saw temperatures reach 32° Celsius (90° Fahrenheit) in the northern city of Norilsk. For comparison, daily July highs in Norilsk average 16° Celsius (61° Fahrenheit). Blocking highs are so named because they block the jet stream from moving rain-bearing weather systems along their normal west-to-east path; this leads to "stuck" weather patterns with long periods of stable air and exceptional heat.

The map above shows land surface temperature anomalies for July 20