Martell: Weakening La Nina Alters Weather Across the United States

March 12, 2012 02:57 AM

The following content was provided by meteorologist Gail Martell of

La Nina Rapid Weakening Alters Weather Conditions

The La Nina began rapidly weakening in late January. This was manifested by strong warming in the eastern equatorial Pacific Ocean. The warming seas reflected changes in the strength and direction of the trade winds. At the same time rainfall patterns also began to change in the Southern Hemisphere.

Argentina began receiving heavy rainfall late in January and February, ending a long drought in the grain belt. Extremely wet conditions have developed over the past several weeks, 150-175% of normal moisture in February and March. Argentina is highly sensitive to the ENSO fluctuation.

Weather conditions began changing in the United States also, as La Nina waned. Several waves of rain and snow showers occurred in Minnesota, Nebraska, South Dakota and Iowa in recent weeks. These key corn states previously had been extremely dry in the August 2011 - January 2012 period.

The subtropical jet stream in the southern United State suddenly strengthened after a long absence, spawning violent thunderstorms, tornadoes and heavy rainfall. Hard red winter wheat farms began to receive valuable rainfall in Texas and Oklahoma, improving crop conditions.

The Climate Prediction Center expects the La Nina to continue weakening in the weeks ahead. The latest sea-surface temperature departure was -0.5°C right on the threshold of "ENSO-neutral" conditions -0.5°C to + 0.5°C.

03 12 12 Sea Surface Temps

South America Soybean Supplies Shrink on USDA March Report

Brazil and Argentina both are expecting worse soybean production compared to last year from damaging drought. When Paraguay losses are factored in, the South America soybean production deficit increases to 12.87 million metric tons versus supplies the year earlier.

The USDA cut the Brazil soybean production estimate to 68.50 million metric tons compared to 75.50 MET last year. The final outcome of this year's harvest hinges heavily on Matos Grosso, the largest soybean state, where an abundant harvest is required in order to offset drought losses in South Brazil.

Mato Grosso producers reportedly boosted soybean plantings 9% this season. The state grows roughly 30% of the national soybean harvest. Dr. Michael Cordonnier Soybean and Corn Advisor has expressed concerns about rust damage in Mato Grosso soybeans, following a spate of heavy rainfall in February.

Farm reports from Rio Grande do Sul indicate devastating damage from historic dryness and heat stress. Water was being rationed in several areas of the state. It seems damage was so severe, not all the soybeans would even be harvested. Parana is anticipating a poor harvest also though loses would not be as extreme, down perhaps 20% from last year. Drought was particularly intense from November-January in South Brazil.

It seems possible South Brazil soybean losses may overwhelm gains in Mato Grosso. The drought stricken southern states make up 35% of Brazil soybean production.

03 12 12 Nov2011 Jan 2012 Drought

Back to Back Record Wheat Harvests in Australia

Burdensome supplies of wheat in Australia have developed from back-to-back record harvests in 2010-11 and 2011-12. Exceptional production in 2 straight growing seasons is linked to the La Nina.

The Australian government's agriculture and economic agency ABARES predicts a record wheat harvest this season with 29.5 million metric tons. It would be the second year in a row of record production. Last year's harvest was nearly as big with 27.89 million metric tons. Rather low domestic consumption means a large surplus of wheat would be available for export, near 22 million metric tons.

There is so much wheat on hand that the government foresees a deliberate action by farmers to reduce wheat production next year. The ABARES forecast is for a 12% cut in Australia wheat production to 26 million metric tons in the 2012-13 crop season.

The Bureau of Meteorology has done extensive research on the La Nina showing New South Wales, Victoria and South Australia to have a strong wet bias from La Nina. This year Western Australia also was extremely wet, promoting a record harvest in the top Australia wheat producing state.

03 12 12 Australia Wet Calendar Year

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