Expect weather to favor a fast planting season across many U.S. grain and oilseed areas, but be ready for a drier than normal growing season in the western Corn Belt and prairies.
Whether La Niña stays or leaves is the key question for spring and summer weather. During La Niña, ocean temperatures in the eastern equatorial Pacific Ocean are unusually cold. Weather conditions tend to be wetter than normal across the Pacific Northwest and drier and warmer than normal in the southern and central United States.
The National Oceanic and Atmospheric Administration has two versions of La Niña's prospects this spring and summer, said Drew Lerner, president of World Weather
. One version predicts La Niña will weaken but persist through spring and summer, taking moisture out of the atmosphere. Another version suggests that La Niña has peaked and will dissipate by April and May.
"There is a huge difference," said Lerner Jan. 20 at the Allendale Ag Leaders Outlook conference. If the second version is right, timely rains will reach the Upper Midwest and Northern Plains this summer.
He argued that the first version, with a bias toward dry weather, is more likely. Eastern Pacific water is colder than normal to a depth of 150 meters, so he expects surface temperatures to also stay cooler than normal.
"I favor La Niña staying through spring and dissipating in summer, but leaving a footprint through the summer," said Lerner.
If he's right, weather in much of the United States and Canada would have a dry bias through spring and summer. "I fully expect dryness in the Upper Midwest of significance," he said. He also expects the Texas drought to continue but weaken, and anticipates dryness to end in the Southeast.
Here are highlights from Lerner's weather outlook:
- Soil moisture is already plentiful in much of the eastern United States, and weather into April will have a wet bias in the Ohio Basin and Delta. Spring planting delays are likely in these areas.
- In the Upper Midwest and northern Plains, precipitation will be less; these areas already have a dry bias on the Drought Monitor.
- Texas historically rebounds partially after a drought, but low reservoirs, rivers, and streams take longer to replenish. "We know Texas will not be fully recovered from the drought no matter what happens in the next few months," said Lerner.
- Eighteen-year cycles – independent of La Niña – also indicate dryness in the Northern Plains and Texas.
In his forecast for weather through spring to harvest, here is what Lerner expects:
- March and April: "Precipitation in early spring is going to continue below average in the Northern Plains," he said. The jet stream likely be far enough to the south that storm tracks will miss much of the Northern Plains and Canada. The weather bias in the Ohio River Basin and parts of the Delta will be toward wetness.
- May and June: The Northern Plains likely will be drier and warmer than normal, abundance of moisture in the Midwest will diminish, and dryness in the Southeast could shift into the Ohio River Basin. Growers in the Northern Plains will plant as soon as it's warm enough. Texas and Oklahoma likely will get favorable rain in late April and May, but their weather will turn drier again in the second half of June. In the lower Midwest and Delta, early spring wetness will lead to some planting delays. "Expect the market to be all over it, with the third year in a row" of delays, said Lerner. "But a week or two after the market gets excited, rain likely will stop."
- Summer: A moderate ridge is likely in the middle of the country, but what happens to La Niña will be an important factor in summer weather. Lerner expects the eastern Corn Belt will get summer rain to relieve any spring dryness that moved up from the Southeast. "The Southeast should see an abundance of precipitation as we move deeper into summer," he said.
- Fall: "Harvest should go extremely well in most cases," said Lerner. He expects the northern Plains to stay dry and anticipates normal harvest in the rest of the country.
- March 2012