Where do record-breaking heat waves come from?

What do the three worst heat waves on record—and the recent Pakistani floods—have in common? All four are the handiwork of a rare "kink" in the jet stream that likely has its origins in wonky sea surface temperatures. Weather Underground blogger Jeff Masters explains how this phenomenon works, and why it can simultaneously lead to intense flooding in Pakistan and a massive heat wave in Russia. (Via Karl Hakkarainen)