Scientists and climatologists say the drought that has plagued Texas and the southwest United States may extend for another year. That’s because there is a 50/50 chance the La Nina conditions in the equatorial Pacific Ocean will return this fall.

The U.S. Climate Prediction Center forecast in a monthly report that "the majority of models" indicated neutral conditions into the fall of this year. The CPC is an office under the National Oceanic Atmospheric Administration (NOAA).

"Beyond the early fall, the forecasts are less certain with half of the models (showing) neutral conditions continuously through early 2012," the report said.

But the latest computer models from the NCEP Climate Forecast System (CFS) models "predict La Nina to redevelop during the fall."

La Nina is a phenomenon of a cooling of the tropical Pacific Ocean and typically results in less rain for southern states. The strong La Nina of 2010-2011 is believed to have caused this summer’s devastating drought.

“I’ve started telling anyone who’s interested that it’s likely much of Texas will still be in severe drought this time next summer, with water supply implications even worse than those we are now experiencing,” said John Nielson-Gammon, the Texas state climatologist and a Texas A&M University professor.

La Nina winters in Texas typically have mild temperatures and drier-than-normal weather. Nielson-Gammon said at least parts of Texas are likely to experience a continuing drought that will stretch on for two or more years.

Water supplies in Texas are now stressed to the point mandatory water restrictions are in place for many communities. Water use is now limited by 796 communities across the state, including 506 which have issued mandatory restrictions.

Some municipalities have even stopped selling water, which was the only available source of water for some livestock owners who were hauling water to their animals.

Texas began 2011 with water reservoirs used to supplement water supplies at 81 percent of capacity. As of August, the state’s reservoirs were at 68 percent of capacity. About 70 percent of Texas rangeland is classified as very poor condition.

The current drought is often compared with the 7-year drought Texas experienced in the 1950s. That drought changed the state’s demographics, with many families abandoning parched farms for cities. The current drought could cause new societal changes, if it persists, because the state now has 25 million residents, compared with the 7 million in the 1950s.