Feature: When El Nino Begins Key for 2014 Growing Season

March 28, 2014 05:41 AM



Odds of El Nino developing this year are increasing, say both the Australian Bureau of Meteorology and the U.S. Climate Prediction Center. With El Nino known as a "friend of the Midwest crop grower," we asked several meteorologists to give us their outlook.

Timing of El Nino critical
Meteorologist Gail Martell of MartellCropProjections.com says after studying late-planting years after a cold winter, she's convinced the weather in July, and a late fall depending on the length of planting delays, holds the key in determining corn yields. As a result, she says a lot is riding on the state of ENSO during the growing season.

"If the Australians and the U.S. Climate Prediction Center believe it’s (El Nino) going to take time, possibly late in the summer, and I have no evidence to the contrary, I can join that camp. What I do know is the timing of the onset of El Nino is important for Midwest crop yields as it causes a wet signal."

But Martell reminds that drought in the U.S. Southern Plains and coldness in the Midwest are La Nina signals. "It takes a long time for all these factors to come into play before a full-fledged El Nino is declared. It takes time for a huge circulation pattern and all the effects we are familiar with in an El Nino to be realized," she says, also acknowledging the strong warming that signals the La Nina effect is eroding. "But it could also be just another shift that keeps us in a volatile weather pattern."

Yield risk higher during volatile cycle period
There are few people that can explain the state of the climate like Iowa State University Climatologist Elwynn Taylor. He says one thing there is no question about is we have moved into a period of greater volatility in regards of crop yields, as he explains during the 1980s we had good and bad crop years mixed together, which included the two serious droughts of 1983 and 1988.

"Then we had the flood of 1993 and another flood in 2008... followed by the drought of 2012," he says, explaining within this 39-year cycle, there are 25 years of high variability (less consistent yields) and more consistent yields the remainder of the time.

Taylor points out the only six-consecutive-year period of above-trendline yields since record keeping became was from 2004 to 2009. He says that got people to really thinking genetics were taking off. "Then came below-trendline yields in 2010, 2011 and 2012, which reminded us weather was still very important," he says.

Since good-crop years are associated with El Nino, Taylor says the timing of the onset of the event is very important. He points out the Climate Prediction Center currently predicts around a 50% chance of El Nino developing by summer and with July and August critical months for crops, if El Nino is delayed until August, there is more yield risk to the crop.

But he also says the movement of the drought from East to West is a more favorable sign for the Midwest, as is the warming of the oceans where El Nino is measured. His current yield calculation, which involves the condition of the ocean currents and temperatures — particularly around Bermuda that is responsible for more than 80% of the precip that falls in the U.S. — the state of ENSO and current soil moisture conditions, points to a corn yield of 166 bu. per acre.

El Nino influences begin before event is declared
World Weather, Inc. Meteorologist Drew Lerner expects to see El Nino-like conditions in May and June if the event is officially declared later in the summer. He notes recent warming signals El Nino is in a big hurry to get started, but says it will need reinforcement of warm waters later this summer to be sustainable.

For the next few weeks Lerner expects a cooler bias across the Midwest, Southeast and Delta continuing and most areas east of the Plains will see normal to below-normal temps into May. The heart of the Corn Belt should see above-normal precip through May, he predicts, which will cause some planting delays. "The majority of the Midwest should see timely precip over the course of the summer, but there will be some problems with a drier bias in southwest Iowa and eastern Nebraska... The bottom line is favorable for most of the Midwest," says Lerner.

But he warns if the drought in the Southern Plains or West does not see significant relief, this ridge of high pressure could become stronger and relocate further west. "If this takes place, the forecast for the heart of the Midwest stays the same, but all of the Plains could see more issues and larger portions of the western Corn Belt, as well. I am not ready to go down that road, as there should be enough cooler air in Canada that will wear against the ridge. Most of the Midwest will do fairly well and the El Nino influence keeps my bias fairly positive," says Lerner.

Lerner also expects drought areas of the western Corn Belt to see some relief over the next four to eight weeks. "It won’t happen all of a sudden, but there will be some relief in those areas. But if that relief isn’t as great as it should be in June as the warm season begins, it won’t take long for those areas to dry out again," he says.

Analog years brought big corn yields
Kyle Tapley, senior agricultural meteorologist at MDA Weather Services, says to start the 2014 growing season, he’s looking at 1986, 1994 and 2009 as analog years -- seasons that concluded with above trendline corn yields. These were years when El Nino was evolving. "It looks like we’re headed toward El Nino, but I don’t think it’s going to be strong enough or become an El Nino early enough to help us... We have seen some warming over the tropical Pacific, so there are signs we could see it earlier," he says.

Tapley doesn’t see reason to be overly concerned about Midwest planting delays, but says temps will remain below-normal through May. "We’re leaning toward the cooler and wetter side for the summer in the Midwest, which doesn’t signal any major crop problems," he says, although noting some concern about the western Corn Belt, as this region could see more influence from dryness and heat from the Southern Plains.

Based on the forecast, MDA Weather Services preliminary national corn yield estimate is 168.4 bu. per acre.


Cooler bias to start planting season
Freese-Notis Meteorologist Dan Hicks says below-normal temps (by 1 to 3 degrees) will extend into April, leading to a slow start to the growing season, especially since soils are still frozen across a large swatch of the region — especially in central and northern portions — although not as severely cold as in March. Above-normal precip is expected across northern areas, with more normal precip expected across across the central Belt.

"The April forecast is based on tendencies for temps to be below-normal during neutral ENSO years," says Hicks, who expects a warmer trend to being in May along with above-normal precip in the northwest Belt and normal precip elsewhere. "Heading into the summer, we’re leaning toward temps near to slightly below-normal and precip near to a little above-normal. We do have what appears to be a trend toward El Nino... It probably won’t develop early enough to provide early summer weather effects. El Nino may be more of a factor for the second half of the year."

Hicks says in making the spring forecast, he looked for years when cold temps were concentrated in the winter in the Midwest and temps were warm in the Southwest U.S. The list was whittled down to three years — 1959, 1978 and 1982. In those springs, temps were cool in April and warmer in May in the Corn Belt.

For the Plains, Hicks is concerned that drought will remain a struggle. "As we get into April there are indications precip will be closer to normal, but based on extended forecasts, it may be May before precip in the region is substantial enough to reduce drought. The drought in the Plains has been around for so long that it will be hard to complete erase," he says, noting that rains may be timely enough to improve winter wheat crop condition ratings.


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