Spring weather to reflect La Niña’s influence

Though bitter cold and sub-freezing temperatures ushered in 2018, the National Weather Service’s Climate Prediction Center forecasts indicate that warmer and drier than normal temperatures are likely from February through May, with La Niña expected to have a significant influence on Texas weather patterns over the next few months.

A trend toward dry weather is already evident. As of mid-January, 97 percent of the basin was experiencing drought conditions, which the National Weather Service noted was nearly double the drought rate from three months earlier. At the same time in 2017, only 18.5 percent of Texas was experiencing drought. Based on the preliminary outlook for spring, dry conditions are expected to linger a while – a product of La Niña.

La Niña is the periodic cooling of the equatorial eastern and central Pacific Ocean. The NWS notes that when sea-surface temperatures are cooler than average by at least 0.5 degrees Celsius, a La Niña is considered to be in place.

Despite the anticipated dry spell, conditions are certainly better than they were at this time three or four years ago.

“We’re not in a prolonged drought pattern yet,” said John Nielsen-Gammon, Texas state climatologist. “The past three years have been rather wet, and the long-term temperature in the Pacific Ocean is still nowhere near as unfavorable as it was in the early 2010s.”

Although 2017 ended – and 2018 began – with intermittent wet weather and lower than average temperatures through parts of the Brazos River basin, that pattern was expected to be short-lived. Dry weather conditions are expected to blanket much of the southern and western United States, including Texas.

Although the state has experienced some temperature extremes to end 2017 and start 2018, that’s actually not entirely unexpected for the type of weather pattern the state is experiencing, Nielsen-Gammon said.

“This is typical for La Niñas,” he said. “Because the northern United States is typically colder during La Niña, there’s always a good chance that some of that cold weather will occasionally invade Texas. The warmer weather during other times in the winter tends to more than cancel it out on average. Variable rainfall from day to day and week to week is a product of the weather but is also, unfortunately, enhanced by climate change.”

While early spring conditions seem pretty well determined by expected weather patterns, it gets a bit more uncertain later in the spring.

“La Niña conditions typically influence our weather through March, so dry and mostly warm, with occasional cold, is favored from now until then,” Nielsen-Gammon said. “After March, the Pacific Ocean temperatures are expected to return to close to normal, so from then on out it will be up to the vagaries of the weather.”

The NWS Climate Prediction Center indicates that dry conditions could change later this spring. The early projection favors neutral conditions (with neither El Niño nor La Niña conditions) this summer “with a slight tilt toward La Niña” returning again later this year, according to the weather service.