Could a pattern shift mean more rain in San Antonio in 2023?

SAN ANTONIO – It’s been a rough few years for San Antonio weather. A multi-year drought has once again drained Medina Lake and the aquifer, while farmers struggle to make yields.

We’ve been here before, though. Twelve years ago, a similar story played out. Drought conditions stretched from 2011 to 2013, and despite some periodic heavy rain events, that carried over into 2015. It wasn’t until the spring of 2015 that Medina Lake filled up, the aquifer recovered, and the drought, for all intents and purposes, ended.

Like everything else in the world, weather patterns tend to work in a sinusoidal curve (think roller coaster). There are nuances and imperfections along the way, but we’re talking big picture here. Scientists, through the years, have found global connections to answer why weather patterns do what they do.

By now, you’re probably familiar with La Nina and El Nino. There’s concrete evidence that ENSO (El Nino and the Southern Oscillation) plays a role in what we can expect in South Texas. It all has to do with the sea surface temperatures in the Pacific Ocean. Take a look at what the ENSO has looked like over the years:

ENSO patterns since 1980 (NOAA)

See the connection? The blue part of the graph represents stretches of La Nina, which we associate with drier weather here locally. The red stretches are El Nino years.

We’ve been in a serious La Nina since 2019. It’s lasted a while. While that helped to crank up the tropics (another known side effect), a historic drought took hold, allowing for San Antonio’s second driest year on record in 2022.

So, here’s the good news: La Nina is winding down. Here’s what NOAA’s Climate Prediction Center is saying:

“A transition from La Niña to ENSO-neutral is anticipated during the February-April 2023 season. By Northern Hemisphere spring (March-May 2023), the chance for ENSO-neutral is 82%.”

This means that we’re headed into a transition period. Typically once we hit a neutral phase, the next step, over time, is for us to enter into an El Nino. This would likely bring rainier and damp conditions back to South Texas. Is it unequivocal? No. But, I’d say there’s light at the end of our proverbial drought tunnel!

One other thing to keep in mind… South Texas tends to come out of droughts in a dramatic fashion. After a dry stretch, it was the Flood of ‘98 that pulled us out of a late-90s drought. In 2015, it was the Blanco River floods that occurred after an extended La Nina drought. History tells us that we should be prepared for flash flooding at some point over the next few years.

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