The following content is provided by meteorologist Gail Martell of MartellCropProjections.com.
Argentine Heat Wave, Dry Forecast
Argentine growing conditions were hot and dry last week increasing stress on corn and soybeans. Stressful weather conditions may reflect a weakening El Nino effect.
Only 15% of the grain belt received significant rainfall in widely scattered showers, while a heat wave produced temperatures 10°F to 13°F above average. On Sunday temperatures topped 100°F in western Buenos Aires to La Pampa. Elsewhere in the grain belt mid 90°s F prevailed.
Rainfall the first half of December was generous in the three main grain provinces Buenos Aires, Cordoba and Santa Fe. However, the extreme heat has also increased evaporation, sapping field moisture. Late- planted corn and soybeans are most susceptible to moisture stress having a shallow root system.
Pehuajo, a key corn area in western Buenos Aires, saw temps just under 100°F at the start of the week. A short-wave disturbance would bring clouds and widely scattered showers to Buenos Aires province Christmas day. Very hot temperatures would resume by the weekend also with dry growing conditions.
The extreme heat is projected to last through Christmas Day. Then there is a 60% to 70% chance for showers by Friday. The GFS predicts variable rains in the northern two farm provinces Cordoba and Santa Fe. Some areas may receive 1.5 inches of rain in scattered strong thunderstorms.
South Brazil Dryness
Dry conditions not only affect Argentina but also Rio Grande do Sul, Brazil's southernmost farm state. Emerging drought in South Brazil has also expanded into Parana, Brazil's second leading corn and soybean state. The dry weather conditions recently in southern South America are just the opposite of what would be expected with an El Nino signal.
Indeed Argentina's most productive grain harvests have occurred when El Nino is in effect. This is due to recent cooling in the eastern equatorial Pacific with a weakening El Nino signal.
The forecast remains hot and dry in southern South America, suggesting the El Nino effect may continue to fade.