Friday, January 30, 2009

La Nina is here. What it means for the United States.

Here's NOAA's Oceanic Nino Index. An official La Nina (El Nino) call requires five overlapping seasons (Jan, Feb, Mar; Feb, Mar, Apr; etc.) of 1/2 degree anomaly. We aren't there yet:













From the Houston Chronicle's SciGuy (which explains the Texas angle):

It may not quite be official, but La Niña, a natural cooling of the eastern equatorial Pacific Ocean, has arrived. Here are the full details from NOAA (.pdf file).

As La Niña conditions will likely persist through at least early spring we can make some predictions about what winter conditions will be like in Texas this year.

The graphic below shows the average temperature anomaly from November through March when La Niña persists in the Pacific Ocean.


As we can see, the average temperature is about 1 degree warmer for southeast Texas. Perhaps more interesting is La Niña's effect on precipitation, especially as we're already having such a dry winter.


Here we can expect to be about 5 inches below our normal rainfall totals, and we seem to be on course for that. We were 1.27 inches below normal rainfall in November, 2.01 inches below in December, and we're already 2.84 inches below normal this month....MORE