Wednesday, September 9, 2009

As El Niño strengthens: A cooler, wetter Texas winter?

From the Houston Chronicle's SciGuy:

After a sizzling summer, I'm ready for winter. Not to mention some rain, given that Houston is about 10 inches below normal on that score. As it It turns out we might just have a cool, wet winter thanks to El Niño, the pattern of warmer sea surface temperatures in the tropical Pacific Ocean.

The latest outlook suggests we're already in a moderate El Niño that is likely to get stronger and persist through the winter. So if that's the case, what does a winter El Niño mean for the Texas climate?

Here's a map showing that Texas typically has wetter and cooler conditions during an El Niño.


So let's see if we can quantify this a bit more for Texas. The following data is based upon average conditions during the 17 El Niños in the last 50 years. The four images below concern the December-February during El Niño winters.

In the first set of photos, the map of the United States on the left shows that all of Texas, on average, experiences at least 10 to 30 percent more precipitation during an El Niño winter. Parts of South Texas have 50 to 70 percent more rainfall. Considering that area's exceptional drought, there may finally be some relief this winter.

The map of the United States on the right indicates the percentage of El Niño years that have had above-average precipitation. For example, South Texas had above-average precipitation in 60 to 80 percent of the El Niño winters.


The maps below also represent average conditions for December-February during El Niño winters, expect they show temperatures, in Fahrenheit, instead of precipitation.

Most of Texas is slightly cooler, and the slightly cool winters occur 60 to 80 percent of the time for most of those areas....MORE