El Nino may bring cooler, wetter winter
Even as the state finds itself almost completely drought-free for the first time in months, parts of Oklahoma could see a wetter-than-usual winter, climate scientists predict.
An El Nino weather pattern that is developing in the Pacific Ocean could spell cooler and wetter conditions across the state, said Kyle Brehe, a regional climatologist for the Southern Regional Climate Center at Louisiana State University.
El Nino weather patterns begin with a warming of surface water in the central and east-central Pacific Ocean. That warming trend creates a domino effect of weather impacts worldwide.
During a media teleconference Friday afternoon, Brehe said El Nino weather patterns tend to mean better chances for cooler weather and more precipitation across the southern Great Plains and the southeast, including Oklahoma. But Brehe said even a strong El Nino pattern doesn't guarantee increased rainfall or colder conditions in any particular area.
“Impacts of El Nino are not spread evenly across areas or across times," Brehe said. "They vary from event to event.”
In Oklahoma, the effects of El Nino patterns can be difficult to predict, said state climatologist Gary McManus. While a moderate to strong El Nino generally means cooler weather and more rainfall beginning in late autumn and lasting through early spring, a weaker pattern has weaker effects.
In fact, over the years, Oklahoma has tended to see drier conditions during weak El Nino events like the one climate scientists predict this fall.
"That doesn’t necessarily mean that’s going to happen," McManus said. "Every El Nino’s different."
Any additional precipitation that comes to the state would arrive on top of relatively heavy rainfall Oklahoma has seen in the summer and early autumn. That rainfall almost completely wiped out the last of a short-lived but intense drought across much of the southern Great Plains, said Victor Murphy, climate services program manager for the National Weather Service Southern Region, based in Fort Worth, Texas.
During Friday's teleconference, Murphy said the drought began to take hold in the region in October 2017 and reached its peak in May. During the drought, more than 350,000 acres burned in Oklahoma, mainly in Dewey and Woodward counties, and 1,500 cattle died in the wildfires.
Fortunately, the drought came during a time of year that, even in an average year, tends to be relatively dry, Murphy said. So increased rainfall in the spring and early summer quickly made up the difference, he said.
Just 1.6 percent of Oklahoma, all of it in the northeastern part of the state, remains in moderate drought, according to a U.S. Drought Monitor report released Thursday. The report is based on data collected Tuesday morning, meaning it doesn't account for any rainfall since then. Most of the affected areas saw a quarter to a half an inch of rainfall in the days after that, according to the Oklahoma Mesonet weather network.
More help could be on the way. The National Oceanic and Atmospheric Administration's Weather Prediction Center forecasts a half inch to 1.5 inches of rain over the next seven days across much of eastern Oklahoma, including the areas still affected by drought. Areas in far southeastern Oklahoma could see as much as 2.5 inches of rain during that period, forecasters predict.