Highlight: Argentina drought worsens despite patchy thunderstorms later this month. MJO supported wet weather is possible middle 1/3 of January for ARG.
Fig. 1-4: GFS rainfall forecast for days 1-5 and days 6-10 (above), the 6-10-day temperature anomaly forecast and 11-15-day rainfall outlook (below).
Discussion: Steadily warmer and dry across the Argentina Crop Areas during the next 5 days (Fig. 1). Rainfall across Brazil is heavy along a stalled frontal system into early next week. In the 6-10-day period, Brazil remains wet (Fig. 2). However, the far Southeast Brazil drought area persists with a general lack of rainfall. In the 6-10-day period thunderstorms develop across Western Argentina. The primary crop areas in Argentina stay dry and turn hot (Fig. 3). A weak upper trough causes scattered showers and thunderstorms across Argentina while wet weather in Brazil is most concentrated in central areas (Fig. 4).
In the extended range, recently issued ECM “weeklies” indicate marginally dry weather for the first half of January (Fig. 5) followed by a wetter trend for the second half of January in Argentina (Fig. 6). The wet risk to Argentina is based on a steady wet northerly fetch of tropical moisture in-between semi-permanent subtropical high pressure areas either side of Argentina. ECM is forecasting Madden Julian oscillation phase_7 in 3+ weeks which favors a wetter Argentina regime during the middle third of January.
Fig. 5-6: The ECM week 3-4/week 5-6 rainfall anomaly forecast across South America