Seasonal change in the weather is increasingly in the scientific cross hairs these days because variations in patterns that help forecasting local weather and the likelihood of floods, drought and other events. New data are being reported and receiving unusual intense interest by the New York Times and other news outlets this summer.
For example, reports Thursday that the world had entered La Nina, a climate pattern with impacts across the globe, was widely reported. Among other impacts, the La Nina emergence is thought to boost the potential this winter to “worsen what are already severe drought conditions in the American Southwest.”
The NYT report was based on recent work by the Climate Prediction Center – part of the National Oceanic and Atmospheric Administration. That agency said in its most recent monthly forecast that sea-surface temperatures in the central and eastern tropical Pacific Ocean had cooled, signifying “La Nina conditions” that likely would continue through the winter.
Like El Nino, which results from warmer-than-normal ocean temperatures in the tropical Pacific, La Nina occurs every two to seven years on average. And like El Nino, it leads to changes in atmospheric circulations that can affect weather in unconnected parts of the world.
La Nina's strongest influence is usually felt in winter, the Times said. And while the precise effects are unpredictable, La Nina can result in warmer and drier conditions across the Southern United States and cooler conditions in southeastern Alaska, the Northern Plains and western and central Canada. It can also lead to a wetter winter in the Pacific Northwest.
Mike Halpert, deputy director of the Climate Prediction Center, said that as a result of La Nina, Southern California, as well as most of Arizona and New Mexico, could “tilt toward dry” this winter.
Southern California, which gets most of its rainfall from late fall to early spring, is already abnormally dry, according to the United States Drought Monitor. Those conditions have contributed to numerous wildfires this summer. All of Arizona and New Mexico are in varying stages of drought, from moderate to severe.
But La Nina can have effects around the globe. The most consistent impact is in Indonesia, which usually sees increased rainfall, but La Nina can also lead to dry conditions in Eastern China and East Africa and cool and wet conditions in Southern Africa and Southeastern Brazil.
NOAA scientists said this summer that the decreasing sea-surface temperatures in the tropical Pacific were a factor in their prediction that the North Atlantic hurricane season would be an active one. La Nina influences atmospheric conditions in the North Atlantic that would otherwise tend to disrupt hurricanes as they form.
Emily Becker, associate director of the Cooperative Institute for Marine and Atmospheric Studies at the University of Miami, said that since the last El Nino ended in 2019, ocean temperatures in the tropical Pacific had been “neutral,” neither abnormally warm or cool. But that began to change this summer. “We saw some pretty substantial easterly winds,” she said. “It might have cooled a little faster than we would have expected, but not radically so.”
These west-to-east trade winds cooled the ocean surface and also led to upwelling of deep, colder water to the surface, Dr. Becker said. The resulting shift of warmer water to the western tropical Pacific affects the jet stream, the high-altitude river of air that moves west to east and serves to separate colder and warmer air. It is this change in the jet stream that can modify the North American winter, Dr. Becker said.
El Nino affects the jet stream, too, although in different ways, and leads to changes that are often the opposite of La Nina's, including wetter conditions across the Southern United States. Dr. Becker said current models suggested that this La Nina would not persist through the spring.
Bloomberg also noted the new climate-change event the Times noticed, but emphasized a further detail. It said that while the crop world, including major trading houses and statisticians at the USDA, has long depended on scouts trudging through fields to count corn kernels and soybean pods, travel restrictions and new virus safety measures “now have cut participation in field tours at a time of increasing scrutiny over food security.”
The report also noted that student Lillian Kay Petersen had won the top prize of this year's Regeneron Science Talent Search, a 79-year-old competition for high school students held by the Society for Science and the Public, for her model that uses daily satellite images to predict crop yields in Africa.
Bloomberg says that even before the pandemic, USDA eliminated part of its in-person field checks. In 2019, it decided not to do so-called objective yield analysis in fields during the month of August and rely more on satellite imagery and phone surveys until fields of corn and soybeans were further developed.
Meanwhile, for its global outlook, the agency already is heavily reliant on satellite imagery and meteorology data, according to Seth Meyer, assistant director of the University of Missouri's Food and Agricultural Policy Research Institute and former chairman of USDA's world agriculture outlook board.
So, we will see. Highly accurate and timely crop data are extremely valuable and ways to improve the current systems have been in development for decades. That search seems far from over, but the stakes appear to be increasing. Certainly, this competition is one producers should watch closely as it continues, Washington Insider believes.