2 July 2012

5 minute read

Drew Lerner, meteorologist and president of World Weather, Inc., told attendees of the Allendale Inc Ag Leader monthly webinar series that the El Niño phenomenon is evolving and will be more visible in late July and August.

To build his forecast, Lerner uses the Southern Oscillation Index. The Southern Oscillation Index, or SOI, gives an indication of the development and intensity of El Niño or La Niña events in the Pacific Ocean. The SOI is calculated using the pressure differences between Tahiti and Darwin. Sustained negative values of the SOI greater than -8 often indicate El Niño episodes.

The Southern Oscillation Index (SOI) gives an indication of the development and intensity of El Niño or La Niña events in the Pacific Ocean. Sustained negative values of the SOI greater than -8 often indicate El Niño episodes. Sustainted positive values greater than +8 are typical of a La Niña episode.

"There are rainfall correlations with the Southern Oscillation Index, and the SOI from May until June falls steadily and becomes negative," he said. "The SOI has been falling over the last several weeks, and we are in the negative now. If the SOI doesn't stay consistently negative in July then this chart will not verify and it will likely stay dry in many part of the world. But this correlation should fit in as long as there aren't other prevailing weather patterns."

Lerner's July, August Forecast

• Mexico's drought continues to be a concern as it is likely to perpetuate itself with below average precipation.
• In south central Russia, there will be a little less dryness.
• New dryness is evolving in southeastern Europe in the month of July.
• Australia will continue to get good precipitation indicating near to above average precipitation levels.
• China's dryness issues will get better in July in the heart of the north China plains.

For August, Lerner anticipates a wetter bias in parts of the world as El Niño kicks in:

• The dryness in Russia is gone in August and should turn wetter than normal.
• Southeastern Europe should also turn wetter.
• The opposite occurs in the now wet Australia - the wet bias will be gone and Australia will turn dry.
• There will be some new areas of dryness showing up in India and parts of China.

Graphic courtesy of Drew Lerner, World Weather Inc.

China

Soil moisture is low in the north China plains and has been for the last 4 or 5 weeks, Lerner said.

"They do irrigate a big percentage of this region," he said. "We don't know exactly what portion is irrigated, but it's likely there will be losses in production for corn, soybeans, cotton and rice. I'm not sure how significant losses will be without knowing how much irrigation is used across the region."

He expects most of the drier bias in the region will slowly fade moving forward through the next few weeks, with late July bringing some rain.

Maps on left show topsoil and subsoil moisture in China. Maps on right show minor and major productions regions for soybeans (top) and corn (bottom). Graphic courtesy and © Drew Lerner, World Weather Inc.

Black Sea Region

The Black Sea and Caspian Sea regions have been critically dry for weeks, and it is going to stay that way for a little while longer. Lerner doesn't expect to see much relief until the El Niño phenomenon fully kicks in during late July to August.

Dryness in the Ukraine has developed in the last two weeks and it is becoming critical.

"There isn't much moisture in the top or subsoil and that means their corn crop is suffering again, and the same is true for some of the sunseed, wheat and sugar beets, as well as, other crops," he noted.

He expects some timely showers will begin in July, but the precipitation will likely come too late for many crops in the lower Volga River Basin where the worst of the drought has prevailed the last three years.

India

El Niño events do tend to make India have poor summer monsoonal rains, Lerner said.

This could have a negative impact on some of the monsoonal performance, meaning the oil seed and coarse grain areas could end up with a restricted amount of rain.

Brazil

Lerner said it's been exceptionally wet in southern Brazil, so much so that it's delayed the second season corn harvest and even some of the wheat has been damaged because of the moisture.

"However, there is still quite a bit of drought going on in northeastern Brazil," he said. "The drought got an early start there and is very serious. There is still sugarcane, citrus and coffee crops in the fields that are being negatively impacted."

In Brazil's winter season, there's not typically a lot of precipitation that occurs. Lerner expects that they'll be able to get the second season corn harvest wrapped up soon but will be fighting some wetter biases as they do so.

"There is an association with the developing El Niño events and above-average precipitation in Brazil, especially when we get into August and September," he said. "What this means for Brazil's coffee country is that we'll see early flowering and there could be a catch-up opportunity for the sugarcane areas as well as setting the stage for the corn and soybean planting areas in the spring."

Lerner said Brazil should have more moisture to work with in the near-term, but could run dry later in the year if El Niño matures.

United States

Lerner said El Niño should bring an increase in the rainfall in the western US and a continuation of below average precipitation in the eastern Midwest, especially in the lower eastern Midwest and the southeastern states. Texas will continue to be drier than normal.

"In the US, the SOI correlations indicate we could have a lot of precipitation occurring if we develop into an El Niño in July-August," he said. "We are going to have greater amounts of precipitation occurring in the Midwest. This might actually help the soybean crop, but it will obviously be too late for the corn crop."

Further Reading To read more of Lerner's weather expectations for the United States, click here.

Sarah Mikesell, Senior Editor

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