La Niña, not Climate Change, Responsible for Southeast Drought

Predicting the weather is never an exact science, but there's good reason to believe forecasts of continued drought in the Southeast, says National Weather Service drought expert Douglas Lecomte.

Lecomte, the author of that rather discouraging graphic to the right, told me that the predictions generated by weather models closely match data gathered made during other periods of La Niña, when the equatorial Pacific Ocean becomes cooler than usual. Said Douglas,

We're pretty pessimistic about the southeast coastal states. The numerical and physical models give the same message: it will be on the dry side in coming monhts, through the winter and early summer, and some of the areas we're talking about already have drought and serious water issues.

But what does the Pacific Ocean's surface temperature have to do with rain falling in Georgia?

What happens in the Pacific doesn't stay in the Pacific. Surface temperatures affect where the thunderstorms are; that affects the air currents; that has an impact on the jet stream. The particular jet stream you get from La Niña results in this high pressure ridging area just weat of the United States. The downstream effect, like throwing a rock in the stream and seeing ripples, is that high pressure builds up over the southeastern United States, which deflects storms into the north. It's not so good for the south.

Researchers have shown that you have quite a reduction in storm systems tracking across the Gulf of Mexico, the ones that bring rain to the
Florida area. There are surprisingly strong correlations between surface temperatures in the Pacific and what happens in the Gulf of
Mexico.

And inquiring minds want to know: is this drought the product of anthropocentric climate change?

I don't want to blame individual droughts or La Niñas on global warming. I don't see that as much of a factor in the southeast. It is a factor in general in the west, where there's less snowcover because of global warming, and higher temperatures than have an impact on the water supply, the timing of the water supply, the timing of the spring flow.

I said there was something reassuring about knowing that the southeastern drought wasn't made by man. I suppose that's reassuring, said Lecomte, unless you happen to live in drought-stricken western areas.

Ouch.

Image: [Climate Prediction Center, NOAA/NWS](http://www.drought.unl.edu/dm/monitor.html)

See Also:

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• Cloud Seeding Won't Bring Rain to the Southeast, Says Climatologist
• What the Southeast Really Needs is a Hurricane