Whats behind a twenty inch rainfall.

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When you get a third of your yearly rainfall in two days, as areas in the Florida panhandle just did, you naturally ask why. The easy answer is that it was the perfect combination of just the right ingredients. 

Radar rainfall estimates

A low level jet of warm humid tropical moisture feed into a large scale low pressure area that moved very slowly. Winds aloft were extremely energetic, acting like a vacuum cleaner and sucking up the moist air from below which is the most basic physics of making rain. Take moist air and lift it, causing it to cool and condense. The entire system moved very slowly causing storm after storm to move over the same area. That's called training and is recipe for heavy rain totals. Yes, that is the simple answer.

The more difficult question is if the production of heavy rain was aided by global warming and climate change.  It is impossible to attribute any one storm to climate change. However, increasingly large, severe or powerful storms is consistent with what climate scientists tell us to expect as temperatures rise.

Chances for heavy rains seems to be increasing

Thunderstorms will be wetter and tropical cyclones will put down heavier rains. Theory suggests this and scientists report that experiments with computer models lend confidence to the idea. With rising temperatures you are basically super charging the hydrological cycle.

So even if pointing to an extreme event, such as the Panhandle floods, and saying, "Ah Ha! Global Warming" is a leap that is difficult to the point of impossible, we had better be prepared for more such events in the warmer future.

John Scalzi