I never much cared about weather—until we moved to Bastrop. In the nine plus years I have lived here my dance card has been filled with diverse Texas weather experiences: ice storms, remnants of coastal hurricanes, droughts, wildfires, floods. The task of reclaiming our property after the Bastrop County Complex fires has opened my eyes to the variability of annual rainfall, temperature and humidity extremes. I have struggled to understand “normal.” Overseeing the re-growth of a loblolly forest has given me new perspective on the heroism of local ranchers and farmers. This is one tough damn place to grow anything!
One weather marvel I have come to value is “the surface temperature of equatorial waters of the Pacific Ocean.” El Nino and La Nina are Spanish words that portend more rain (El Nino) or less rain (La Nina) for South Central Texas. When I first heard the words “El Nino,” as a non-Spanish speaker I harbored thoughts of a charging bull, a phantom pirate ship or some scurrilous border town intestinal disorder. To my surprise, it means “the Christ Child.” Oops! Seems the phenomenon was first commented on by Peruvian sailors in the early 1890’s who named the warm north-flowing current “El Nino” because it was most noticeable around Christmas.
El Nino is associated with higher water temperatures and La Nina is forecast when water temps are lower (than a certain threshold). After years of drought, I just knowingly experienced my first El Nino event last year. I measured almost 59 inches of rainfall in my gauge in 2015 and have received nearly 39 inches through June 2016. The average annual rainfall in our part of Texas is between 28-40 inches. The Lost Pines Nature Trails flooded four times in the 12 months ended in May 2016. Supposedly, it is in a 500-year flood plain. Over 30 homes in the Tahitian Village subdivision were damaged by flood waters last May as heavy upstream rains required opening of flood gates at Mansfield Dam. They stayed open for days.
A young family used to live below our place on the downslope of a rolling hill near a dry ravine. Until last year never had I seen that ravine be anything but dry—until El Nino arrived. Twice in the last year it became a raging river, channeling excess ground water toward Bastrop State Park. The rain fell with such fervor, the world disappeared. We saw boats attached to trailers, refrigerators and miscellaneous possessions floating on the current like toys in a bathtub. During the Memorial Day Flood of 2015, the water got to within a few feet of this young couple’s doorway. In the dark of night, people and pets had to be evacuated uphill to our home as we watched the relentless rain. Had they not made the effort to move their family car to higher ground, it would have been inundated. Almost exactly a year later, it happened again—this time the home and vehicle were total losses. The young family has moved away, discouraged and defeated.
El Nino/La Nina meddles with much more than mere rain events, showing the effect to be a truly global phenomenon. In 2015 and 2016 El Nino was tagged as the culprit for raging wildfires in Indonesia, an outbreak of disease on the west coast of Africa and large scale extinction of seals and sea lions off the coast of California. That’s a lot of
mischief for a few degrees variation in water temperature! El Nino/La Nina also affects wind patterns which, in turn, further amplifies the temperature anomalies. This coupling is a critical component of the phenomenon.
If El Nino & La Nina are Bonnie & Clyde, then the National Oceanic and Atmospheric Administration (NOAA) is the obsessed Texas Ranger, Frank Hamer. Other weather related organizations also participate in tracking and predicting the effects of these atmospheric conditions, but NOAA is the main actor. Satellites, moored buoys, drifting buoys, sea level analysis and a dedicated research ship are used to collect and analyze data. NOAA’s National Centers for Environmental Prediction manipulate large computer models of the global ocean and atmosphere. Additionally, other models are used for El Nino research, such as those at NOAA’s Geophysical Fluid Dynamics Laboratory and other non-government research institutions.
Accurate predictions are important to many people and industries. This is particularly true in the food producing industries,
thus affecting worldwide commodity prices and the economies of different countries. Food and other forms of generalized inflation can occur, even triggering unrest in commodity-dependent poor countries that primarily rely on imported food. Construction and services activities can also be impacted by an El Nino event, reducing productivity and costing millions of dollars in lost revenue.
The science behind the occurrence is daunting and well beyond me, but a simple understanding may be helpful. Something known as the El Nino Southern Oscillation (ENSO) is a recurring weather phenomenon, of which El Nino/La Nina are opposite ends. Evidence has been found that ENSO El Nino conditions existed as far back as 10,000 years, but they have occurred every two-to-seven years for at least the last 300 years. These periods typically last 9-12 months. The strongest link between sea surface temperatures and the wind and rain typically occur between December and April for the U.S. because this is when the water is warmest. Warm water feeds thunderstorms; thus, more rainfall. By contrast, La Nina, a period of less rainfall, typically lasts 1-3 years. So, it’s a lop-sided affair with drenching rains more infrequent.
Although there is a definite link, El Nino does not “cause” individual storms or weather events, rather it creates conditions which influence them. Position and intensity of the jet stream are changed by El Nino, which changes pockets of high and low atmospheric pressure, which, in turn, affects the intensity and track of storms. Since a strong jet stream is an important ingredient for severe weather, the position of the jet stream helps to determine the regions more likely to experience tornadoes, for example. During El Nino, the jet stream flows from west to east over the southern U.S.; during La Nina, it is further north.
Ever notice how the evening news almost always features some weather related disaster somewhere in the lower 48? The cycle of drought and wildfires, rain and floods seems to be more pronounced and unpredictable. Is it due to global warming? Fact is, we simply don’t know. What we do know is that there is truth in that old cliché about ‘if you don’t like the weather in Texas, just wait a minute.’ All of which is to say be careful what you wish for. . .rain can be even more destructive than drought. The people who suffered along the Blanco River in May of 2015, Onion Creek in October of 2015 and the Colorado River this spring owe it all to El Nino. The past is still all we know of the future.