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As La Niña Fades, Meteorologist Predicts Cooler, Wetter Spring for Northern Midwest
The weak La Niña that started in the second half of 2016 is likely to dissipate in the next month as sea surface temperatures warm in the tropical Pacific Ocean. Most climate models now indicate neutral conditions for the spring and summer of 2017.
Unlike with a strong El Niño or La Niña, there isn’t a strong cause and effect with neutral conditions, says meteorologist Dan Hicks with Freese-Notis Weather. “To find some correlation, I looked at years when we had a weak La Niña followed by neutral conditions,” he says. Based on this analysis, these are the trends Hicks predicts for this spring.
Cooler, Wetter Conditions in Northern Midwest
In the years that Hicks analyzed, there was a tendency for spring temperatures to be below normal in the northern Plains through the Great Lakes. This same area also tended to receive above-normal rainfall.
“A lot of that region, especially the northern parts of the Midwest, has a high amount of soil moisture already,” says Hicks. “If you combine that with wet, cool conditions, there might be a slow start to spring fieldwork.”
Warmer, Drier in Hard Red Winter Wheat Area
Contrary to the northern Midwest, the south-central and southeastern part of the country tend to have warmer-than-normal conditions in years where neutral conditions followed a weak La Niña. Below-normal precipitation was also more likely in the spring for the southern half of the Plains through the Delta.
This region includes the hard red winter wheat area, which spans from southern Nebraska through northern Texas. “Short-term, the moisture situation in this area is greatly improved because of recent winter storms,” says Hicks. “However, if this spring forecast were to come true, this will be an area with an increasing need of more rain during the spring.”
Better Planting Conditions for Delta, Southeast
Winter precipitation has also improved drought conditions in the Delta and southeastern U.S.
“These areas had a dry fall, but have had a good amount of winter precipitation since then,” says Hicks. “Even though drought conditions haven’t been eliminated, given the winter weather pattern and soil moisture, these places will be in better shape when planting season arrives.”
While Hicks does have a summer outlook, he was quick to point out that summer weather is harder to forecast. For starters, summer weather isn’t as correlated to the Pacific temperatures as winter weather is. In other words, the change from La Nina to neutral conditions does not indicate as much for summer forecasts as it does for spring. Second, in the years that Hicks examined, there was a lot of variability.
“The first thing that stands out to me for the summer is that nothing stands out,” he says. “In past summers like this, we’ve had some dry areas, some wet, some warm, and some cool.”
Given the trends in the previous years, Hicks decided to draw a map showing what the anomalies for the summer might be. For the Midwest, the map shows normal temperatures in the west and below-normal in the east. Temperatures will also be normal in most of the South, rising higher in the Plains and lower in the Carolinas.
For rainfall, Hicks forecasts below-normal from Texas through southern Mississippi as well as the northeastern Midwest. Above-normal is anticipated from southwestern Midwest into the central Plains.
Overall for the summer, Hicks doesn’t see any huge concerns for the Midwest as a whole.