Parts of the Balkans region received three months' worth of rain in just two days last week, leading to flooding that has left at least 20 people dead, and forced tens of thousands to evacuate their homes.

The flooding, which triggered more than 200 mudslides, resulted from an area of low pressure that was cut off from the jet-stream winds that typically steer storms along from west to east in the Northern Hemisphere. Instead, this storm meandered in place for several days, drawing moisture from the Mediterranean Sea, and dumping up to a foot of rain in Serbia and Bosnia-Herzegovina.

Serbian Prime Minister Aleksandar Vucic declared a state of emergency for many cities and towns, including the capital, Belgrade.

"This is the greatest flooding disaster ever. Not only in the past 100 years; this has never happened in Serbia's history," Vucic said at a news conference, according to Reuters. "More rain fell in one day than in four months."

The flooding has unearthed unexploded land mines left over from the Bosnian War of the early-to-mid 1990s, posing a threat to civilians and rescue workers. Floodwaters have swept into parts of Serbia's largest power plant, the coal-fired Nikola Tesla plant, according to the Associated Press. Workers are trying to prevent the water from disabling it.

The extreme rainfall amounts are consistent with observations in many parts of the world, which show that as Earth has warmed in response to manmade emissions of greenhouse gases and other factors, heavy precipitation events have become more frequent and severe. Recent years have brought several major floods to Europe, including a severe flood event in Germany, Poland and the Czech Republic last year that cost $16 billion, according to Bloomberg. A report released earlier this month that focused on the effects of climate change on the U.S. found that extreme precipitation events have increased by 71% in the Northeast since 1958.

Other parts of the U.S. also saw increases in heavy downpours, although not as significant as in the Northeast.