This image from Climate.gov is the perfect visual depiction of El Nino. It shows the departure from normal water temperatures in the Pacific Ocean, clearly indicating that, as of January 2016, the water off the west coast of the Americas is WAY ABOVE NORMAL. But El Nino is forecasted to end soon, so what will that mean for our weather?
First, what caused that big warm up in temperatures in the first place? Off the coast of South America, the prevailing trade winds flow from east to west. In a normal (La Nina) year, those trade winds are strong. During an El Nino year, for some unexplained reason, those trade winds slow down… way down. The strong trade winds “PULL” the ocean water away from the coast, causing an up-welling of colder water. When those winds become light, the “PULL” on the ocean water is weak, and water warms up.
El Nino causes all kinds of extreme, crazy weather. 2015 turned out to be a very wet year for Texas. For example, Brownsville recorded a total of 46.86 inches of rain for 2015, when normal was only 27.44 inches. San Antonio received 44.22 inches; 32.27 in. was normal. Dallas received 62.61 inches; 36.14 in. was normal. Even arid El Paso received 12.08 inches when normal was only 9.71 in.
El Nino has also been the cause of extremely warm weather for February. For example, on February 15, McAllen hit a record 93! That blew away the old record of 91 set back in 1962.
Forecasters at NOAA see indications that those trade winds near the equator are starting to increase in strength again. If so, then the water off the coast of South America will start to cool back down to normal and take us back into a normal, or La Nina, year.
Generally, in a normal (La Nina) year, which appears to be on the horizon for 2016, precipitation in the southwestern and southeastern states is usually below average.
Another undesirable effect on a La Nina year is that it allows for the development of many stronger-than-average hurricanes in the Atlantic Ocean.