Texas State Climatologist and Professor of Atmospheric Sciences at Texas A&M, John Nielsen-Gammon, has released a detailed report on the causes and implications of this year's drought.
According to Nielsen-Gammon,
"Because of the return of La Niña conditions in the tropical Pacific, a second year of drought in Texas is likely, which will result in continued drawdown of water supplies. Whether the drought will end after two years or last three years or beyond is impossible to predict with any certainty, but what is known is that Texas is in a period of enhanced drought susceptibility due to global ocean temperature patterns and has been since at least the year 2000. The good news is that these global patterns tend to reverse themselves over time, probably leading to an extended period of wetter weather for Texas, though this may not happen for another three to fifteen years. Looking into the distant future, the safest bet is that global temperatures will continue to increase, causing Texas droughts to be warmer and more strongly affected by evaporation."
You can read the full, in-depth report here.