The cause of this cold lurch was seemingly settled some time ago when Wallace Broecker, a Columbia University geochemist, suggested that a North American ice sheet collapsed, flooding the Atlantic with fresh water, which interrupted the normal circulation of the Gulf Stream.

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Later in the summer, the jet stream moved back to its normal position and the usual rainfall service was resumed.

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Warm conditions in the Atlantic and cooler conditions than normal in the Pacific Ocean also have forced the jet stream farther north and created a corridor for newly born hurricanes to move unimpeded from the ocean waters up the Atlantic coast, Liu said.

CNN: graphic