South America Late December Weather Update

December 27, 2011

Dryness in southern South America was interrupted by a wave of very heavy rainfall in northeast Argentina and southwest Brazil, but dry conditions are resuming in late December.

 

Mato Grosso Brazil Getting Beneficial Rain

Mato Grosso growing conditions in soybeans have improved with daily showers in the key Center West area the past couple of weeks.   Conditions were very dry from late October to early December.  

Poor soybean prospects have continued in the southern part of the state with only minor relief from drought.  Southern Mato Grosso soybeans  make up a small fraction of the state total.  

 

South Brazil Drought a Growing Concern

Drought has worsened in South Brazil in December.   It is the second month in a row of abnormally dry conditions in Parana and Rio Grande do Sul.  Weekly rainfall amounts in mid summer should be between 1.2 and 1.5 inches, but instead, rainfall has fallen consistently short of normal and under .75"   Persistent dryness  may be due to a growing influence from La Nina.

Virtually no rain occurred last week in Parana, the number 2 Brazil soybean state and leading corn producer. This is highly unusual in December,  normally a very wet month.  Rio Grande got heavy rain in the southwest,   but continued dry elsewhere in the state. 

 

A strong wave of showers moved up from Argentina into Paraguay and south Brazil, ahead of Christmas.  This was a small, but concentrated area of heavy rainfall.   Whereas southwest Rio Grande do Sul got beneficial heavy rain,  the balance of the state missed out.   Rio Grande do Sul is the number 3 top Brazil corn and soybean state.

The South Brazil forecast continues drier than normal in the week ahead.  There may be a chance for rain in Parana on the New Year's weekend, but but these are expected to be hit-or-miss showers.  See drought on the 30-day rainfall analysis.

 

Argentina Drought Resumes 

Argentina received heavy rainfall in a concentrated area of eastern Buenos Aires, Santa Fe and Entre Rios.  At the same time, drought worsened in the western corn and soybean belt.  

December has been very hot, stressing corn and soybeans with frequent days over 88 F.  Temperatures in the Argentina grain belt are rather moderate,  normally,  with low-mid 80s F and similar to the US Midwest.

The past 30 days, Junin northern Buenos Aires has received only .23 inch of rainfall and 5% of normal moisture.  Temperatures have exceeded 90 F on 11 of the past 30 days causing undue stress in corn and soybeans.

 

A strong cool front passed through the Argentina grain belt ahead of the Christmas holiday,  but relief was short-lived with cooling for only 3 days.  Maximum temperatures reached 90 F yesterday in Junin, Buenos Aires.   Cordoba also is turning hot again. 

 

 

A desert-like atmosphere is resuming in the post-Christmas week in Buenos Aires, the top corn province.  Hot days (near 90 F) and cool nights (mid 50s F) are predicted the balance of the week.   The wide daily range in temperatures is common with dry air induced by a ridge of High Pressure.    This is La Nina signature weather.

Argentina's weather forecast is dry in the upcoming week, except for showers this weekend in southwest Buenos Aires province and La Pampa.   Argentina corn and soybeans are still under threat from dry growing conditions.  

 

Low rainfall is predicted in the week ahead: