La Nina weather pattern brings rain, causes fires for South Central Texas

SAN ANTONIO - The Earth is an ever-changing object with two large dynamic systems driving change over surface and in the air.

These two systems, the atmosphere and the oceans behave as fluids. One gas, one liquid, a movement or change in one mirrors a chance in the other. Unusual conditions produce changes called osculations in our atmosphere and in the oceans.

The result can produce significant impacts on the planet.

Jason Runyen, meteorologist for the National Weather Service in New Braunfels, keeps track of these oscillations and their impacts in our area. One of those oscillations is called "La Nina."

"So the El Nino southern oscillation plays a huge influence in participation patterns all across the globe and in South Central Texas," Runyen said. "When we are in a La Nina across the equatorial pacific, that typically tips the odds towards a drier and warmer winter and spring here in South Central Texas."

La Nina oscillation has been in full swing for hundreds of years, providing times of rain and times of drought.

"1954 to 1956 was our strongest La Nina on record," Runyen said. "And you can see some of our driest years here in San Antonio on record. 2008, another La Nina event -- a very dry year. 2011 -- our worst one year drought in Texas history, our 14th driest period here in San Antonio out of 132 years. So certainly our driest years are normally tied towards the La Nina events that we have."

Ultimately the region has to rely on what precipitation we get and conserve it to get us through the dry times.

"San Antonio has been one of the best examples of conserving water," said Ron Green, Southwest Research Institute. "But over the past 28 years or so population has increased by 40 or 50 percent. The amount of water being used by the greater San Antonio community has stayed about the same and that's impressive."

Another threat La Nina brings is wildfires. South Central Texas is home to dense thickets of Ash Juniper Trees, which is fuel for wildfires.

"The hazard or the danger that you'll have an ignition," said Marc Janssens of Southwest Research. "And a wildland fire is much greater after prolonged periods of drought.

"Once those cedar trees hit a certain threshold of fuel moisture, we really see them pick up in fire behavior," said Logan Schershel of the Texas Forest Service.

You would see the canopy of the trees start to burn and that's when it becomes a big problem.

"South Central Texas has natural pathways for fires called wild lanes," Schershel said. "They've been there for thousands of years and become active before and during periods of drought. It's only recently these wild lanes have become a problem."

The issue is people moving in these traditionally wild land areas where fire is a natural occurrence.

But getting people to live with fire is where the issue is. We are building homes in areas that are traditional wild land, when a wildfire moves through we lose homes.

Conditions across the equatorial pacific area are signaling a La Nina episode that will most likely last into the spring months. This will bring a dry weather pattern to the region along with increased chances for drought and wildfires in the coming months.