Persistent La Niña promotes drought

Drought continues to prevail from southwestern Canada’s Prairies through the entire western half of the United States. January and February weather allowed the drought to expand eastward into the western US Corn Belt, which is a bad omen since winter is normally a time for diminishing drought rather than expanding it.

La Niña events remove moisture from the mid-latitudes in both the Northern and Southern Hemisphere. Dryness that occurred in the summer 2021 in Canada and the central United States impacting crop production could easily be attributed to La Niña with some help from the negative phase of Pacific Decadal Oscillation (PDO). Dryness last summer in Russia’s eastern New Lands and Kazakhstan also can be linked to La Niña.

Multi-year droughts occurred in the 1930s and 1950s and each were associated with lengthy La Niña events. Each of the prolonged La Niña events always occurred shortly after the solar minimum in sunspots. Normally, the longer La Niña events occur in every other 11-year solar cycle.

The statistics suggest La Niña will prevail longer and that has been this meteorologist’s concern for an extended period of time. All indicators are suggesting this La Niña will be around through the entire spring and now there are a few forecasters suggesting it will linger into the summer.

With drought already in place across the central and western parts of North America there will already be potential for a high-pressure ridge to develop over the US Great Plains during the middle and latter part of spring. If La Niña lasts through spring that would be long enough for the summer ridge of high pressure to begin to build strongly across the region prior to the arrival of summer heat.

The earlier-than-usual development of high pressure in the central United States will suppress rain events and allow warming to occur, which will further exacerbate the dryness. Essentially, La Niña conditions that last through spring will leave behind enough dryness in agricultural areas to allow drought to begin festering, expanding and intensifying, which could lead to a more serious bout of dryness. If La Niña does go away after the ridge is well established in June there would not be enough time to change the weather pattern until seasonal cooling arrives in the late summer or autumn resulting in a more persistent ridge of high pressure and greater drought regardless of what happens to La Niña after June.