A move away from La Niña conditions in the Pacific Ocean, replaced by either neutral conditions or a move toward El Niño, could result in favorable summer weather for growing crops, University of Missouri atmospheric sciences professor Tony Lupo says.
“Neutral or heading to El Niño, typically what we see is a mild summer and above-normal precipitation,” he says.
This shift is expected because La Niña conditions have lasted for three years. Lupo says it is only the third time since 1850 La Niña conditions have lasted three years, and they have never seen four years in a row of La Niña, so a shift to neutral or toward El Niño is a good expectation.
“We’re going to bet on it departing, and there are signs it is departing,” he says.
In the immediate future, Lupo is expecting plenty of precipitation for the spring.
“For the spring, I see a continuation of these low pressures coming through our area, and it’ll bring ample precipitation,” he says. “…We’ll see plenty of rain in the spring and temperatures above normal.”
Lupo also cautions that with some areas of the Midwest and West in drought, and others not, people should be on the lookout for severe weather this spring.
“When you get into March, April, May, you tend to get the storms,” he says. “Severe weather will pop up on the borders of areas where it’s dry and more wet areas, like Missouri.”
Lupo says spring is the rainiest time of the year, with almost a quarter of Missouri’s average annual rainfall coming in April and May.
He says it is looking like an early spring in the Midwest. Then the summer will show the results of the La Niña and El Niño situation, Lupo says.
“The key thing is not whether we’re El Niño or La Niña, it’s the direction of the change,” he says.
Lupo says El Niño conditions are “the 800-pound gorilla” of North American summer forecasting, although other factors come into play, such as the pattern and waves of the jet stream.
“We’re in the middle of the country, so some of that depends on how the long scale pattern sets up across the USA, how the waves and jet stream set up,” he says.
Also, there can be ridges in the jet stream known as blocking, and Lupo says blocking in the east Pacific can mean a more favorable summer.
This growing season comes after a winter that looks to be slightly milder overall than others in the recent past.
“It’s a little milder than the past two winters, and that’s typically what happens with extended La Niñas,” Lupo says.
For the weather station in Columbia, Missouri, Lupo says temperatures have been a few degrees higher than average, but “nothing to write home about.” Also, while many areas have seen less snowfall than they typically do, rainfall has largely made up the difference in his area.
“We’re pretty close to what we would be thinking precipitation-wise,” he says.
Drought conditions are varying across the Midwest. According to the U.S. Drought Monitor map released Feb. 23, less than 2% of Missouri and none of Illinois were in drought, while about 40% of Iowa was still facing drought conditions.
The U.S. government’s National Oceanic and Atmospheric Administration is currently projecting generally normal temperatures for Missouri, Iowa and Illinois in the months of March, April and May, with above-normal precipitation for most of those three states.
For the summer months of June, July and August, NOAA is predicting a slight chance of above-normal temperatures for Missouri and Illinois, with a normal temperature expectation for Iowa. The agency is predicting either a slightly above normal or normal precipitation outlook for those three states during those summer months.
