Ag Weather Forum

Scattered showers have returned to central Brazil since late last week and some areas from Parana up to Mato Grosso, Tocantins, and western Bahia have seen some significant rainfall. Other areas have not been as lucky.

A strong front will sweep through the country this weekend though and will likely bring widespread precipitation. But it could go up close to the equator and that may mess up the monsoonal pattern for a bit.

Recent rainfall has been scattered in central Brazil. In the aforementioned zone, areas receiving more than 25 millimeters (1 inch) of rainfall have been consistent near Parana in the south but very spread out elsewhere. That is pretty typical of monsoonal pop-up showers, especially for the middle of October. However, after more than two weeks of complete dryness, and in some cases more than three, the rainfall is desperately needed for soybean planting -- and soon.

Though Mato Grosso got off to an extremely fast start on soybean planting, that pace slowed significantly last week because of the dryness. Producers need the rainfall to be consistent to ensure good germination and early growth as there is no subsoil moisture to rely upon after four to five months of near-complete dryness during the dry season.

Luckily for producers there, a strong front is currently building over northern Argentina, far southern Brazil, and Paraguay. The front will have significant moisture to work with and the forecast is calling for widespread rainfall as it pushes north through Brazil this weekend. Typically, fronts this time of year stall in central Brazil and continue heavy rainfall for a few days before they fizzle out and a return to monsoonal showers resumes. However, this front may be too strong.

Cold air building in the southeast Pacific will flow in behind this front and push it north of 10 degrees south latitude and could make it close to the equator early next week. The normal monsoon flow from the north would be halted for a period. Colder, drier air flowing into southern and central Brazil will likely shut down or limit showers for several days behind it. Though precipitation is forecast to be significant with the front -- more than 25 mm is forecast to be widespread across the area -- the dryness that follows it would not be very favorable for planting or crop development.

The front is forecast to fizzle out by the middle of next week and the slow return of moisture southward into central Brazil would resume. But that may take several days to get the rainfall going again. Instead, the region may have to wait for another front to move in from the south next weekend, in the Oct. 26-27 time frame. Relying on fronts to produce rainfall in central Brazil is not normal and is not favorable. Though southern Brazil is liking this periodic rainfall from fronts, central Brazil needs to see the consistent monsoonal showers and quickly.

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John Baranick can be reached at john.baranick@dtn.com

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