El Nino to bring some raindrops

AUSTIN (KXAN) - Recent rain has eased the drought in parts of Central Texas, but it has not been enough.

Areas like Caldwell, Bastrop and Lee counties are still suffering from the most severe drought conditions ever. Climatologists and meteorologists are hopeful a weak-to-moderate El Nino pattern means above-average rainfall this winter.

El Nino occurs when the Eastern Pacific Ocean water warms. During an event, the jet stream becomes more zonal and can push more storm systems through the Southern United States. El Nino events occur on average every three to five years.

“We’ve gone back and looked at 17 cases of past El Nino events, and we’ve seen in general about a 30 percent increase in precipitation during the wintertime months,” said Paul Yura, the warning coordination meteorologist for the National Weather Service office in New Braunfels.

The rain deficits in Central Texas are great, more than 20 inches in some places. A moderate El Nino event may not erase the drought.

“Not all El Nino [events] do the same thing,” said Professor John Neilson-Gammon, with the Office of the State Climatologist of Texas. “Even if we get normal rainfall these next few months, we’ll still have big hydrologic deficits, big soil surface moisture deficits and we’ll be vulnerable again going into next summer.”

Getting all the rain at once would cause another problem.

The Interstate 35 corridor lines Flash Flood Alley. Heavy rain often floods low water crossings and causes hazardous conditions. Flash flooding is the number one weather-related killer. Nine people died in flash-flooding events between 1996 and February 2008 in Travis County alone.

Slow, steady rainfall is ideal.

"Some of those tenth- to [quarter-inch] every day for 90 days,” said the Climate Prediction Center’s deputy director Mike Halpert. “People would get driven crazy by it, but it would be a good thing for the water-resource issues in Texas."

El Nino can also suppress hurricane development in the Atlantic with a strong jet stream. This season, there have been only six, named storms.

“Given the active era that we’re in, I would suspect, without El Nino, we’d have twice that number,” said Halpert. “So, while we might see another storm or two, I would expect this year to a suppressed-type hurricane season.”