Adios La Nina! NOAA declares weather pattern over

La Nina, a weather phenomenon that has affected global temperature and moisture patterns for the last three years, has been declared over by the National Oceanic and Atmospheric Administration (NOAA.)

In a media briefing on the agency’s spring outlook, they also declared California’s historic drought to be at least halfway over.

With continued storms lashing California and the western United States, and historic snowpacks in the mountains, NOAA officials said in the agency’s Spring Outlook that exceptional and extreme drought in California have been wiped out for the first time since 2020. More rain and snowmelt is expected to further improve drought conditions this spring.

The Spring Outlook, released March 16, highlights temperature, precipitation, drought and flood predictions for April through June. According to NOAA officials, those atmospheric rivers hitting the West Coast, and snowmelt will further improve drought conditions across much of the western United States. Better weather conditions in the Plains are likely to affect grain production in the United States.

In an important part of its spring outlook, NOAA declared that La Nina, the cool phase of the El Nino-Southern Oscillation pattern (ENSO) pattern is over. After basically three years of the oceanic temperature conditions that are called La Nina, the southern Pacific Ocean region has returned to a neutral pattern. Recent ocean temperature readings were not higher or lower than long-term averages – so it’s called neutral.

The cooler ocean surface conditions that are part of La Nina have led to warm and dry conditions in much of the breadbasket of the United States. Wetter conditions than normal have been part of the picture for South America’s corn and soybean growing regions.

An ENSO-neutral condition is likely to continue through the summer, said one of the National Weather Service’s top prediction specialists, Jon Gottschalck. After that there are higher chances that El Nino will develop, he said.

Forecasters at NOAA seem to agree that these neutral conditions will remain through the spring at least and maybe beyond that. If those neutral conditions do indeed continue it means that the tropical region of the Pacific Ocean will not be a factor in weather conditions affecting the Great Plains, Argentina, or Brazil – South America’s grain powerhouses.

In official ENSO probabilities released by NOAA, four computer climate models strongly predicted that this neutral status would continue. Four other models suggested a return to an El Nino pattern. A fifth model was about even in predicting neutral conditions and the return of El Nino. But all nine of the climate models agreed with the conclusion that La Nina is over.

The forecast consensus reflects chances of about 60 percent that El Nino would return by the fall of this year. The weather service’s blogger Emily Becker said that NOAA has historical data going back to 1950 and it shows we have not gone more than four years in a row without an El Nino. “If we don’t get an El Nino in 2023-24 that will be five years,” she wrote.

The reason people – especially in agriculture – care so much about El Nino and La Nina is that those patterns can often be predicted in advance and can give people an early idea of the potential seasonal weather trends that might be expected.      

El Nino is what they call the warming of surface waters in the equatorial Pacific Ocean. Winds at the surface of the water blow from east to west, causing these warmer waters to coalesce near Indonesia and Australia. Over that warm pool of water, the atmosphere heats and conditions favorable for rain are present there.

The weakening of the winds is the first sign that an El Nino event is underway. As winds die down, unusually warm water accumulates off the coast of Ecuador and Peru and peaks around Christmas-time. The fishermen that first observed this named it El Nino for the Christ Child.

El Nino events usually occur every two to seven years and there are varying degrees of intensity and duration.

Corn yield effects

Using previous El Nino events as examples, experts say it is uncommon to have below-average overall yields for corn and soybeans in an El Nino year in the United States. Corn yields are usually improved in an El Nino year. It also depends on the strength of the weather phenomenon.

Strong to very strong El Nino patterns can bring record warmth to much of the United States and those warmer temperatures can carry on into the fall, providing temperatures to finish corn and soybean crops.

During a media briefing March 16, NOAA officials said that more than half of the United States saw their top-10 warmest winter seasons on record. That warmer weather also contributed to well below normal snowfall for the mid-Atlantic and Northeast. However, on the whole, total winter precipitation was above average across the country, they said, ranking as the third wettest December through February on record.

Most of that precipitation resulted from a parade of storms from the West into the northern states. In California, the ongoing drought was nearly cut in half between early January and late February.

Moderate to exceptional drought coverage across the United States is at its lowest since August 2020 and is expected to continue improving or end entirely in much of California and the Great Basin. A wet spring season is expected to improve drought conditions in the northern and central Plains.

The northern and eastern half of the country should expect above-average temperatures for April through June and NOAA forecasters predicted above-average precipitation across the Great Lakes region, Ohio Valley and into parts of the mid-Atlantic and Northeast from April to June.

State predictions

The predictions had Wisconsin’s seasonal temperature outlook pegged at “equal chances” of below normal and above normal. North Dakota and parts of South Dakota and Minnesota were predicted to see below normal temperatures with a greater likelihood of above-normal temperatures in Texas and Florida and up the Eastern seaboard.

“Leaning above” normal temperatures were states in a swath from Oklahoma, Arkansas, Tennessee, eastern Kentucky and Ohio and all the way up to Maine.

The agency’s seasonal outlook showed a drought tendency to continue or worsen in western Texas, Oklahoma and Kansas. Drought conditions were predicted to improve or end in the central Plains states and up into Montana, as well as throughout Nevada and Utah.

In reporting on flood potential, NOAA officials said 146 million people are at risk for flooding in their communities, with an additional 6.4 million at risk for “moderate” flooding. An estimated 1.4 million people are at risk for major flooding – extensive inundation of structures and roads.

This spring, NOAA predicts moderate to major flooding in the Mississippi River Basin, mainly from St. Paul, Minnesota to St. Louis, Missouri. Higher than normal snowpacks in the Dakotas may contribute to flooding in those states. Moderate flooding is expected along the lower Ohio River below Paducah, Kentucky. That may not be a bad thing since that region experienced such drought last year that barges were not able to carry grain down the Ohio River to elevators on the Mississippi.