Subtropical Ridge Split: Wetter Medium-range Forecasts for Central Brazil

Next 10 (Hot and Dry) Days Important Determining Central Brazil Summer Drought Risk
11/09/2023, 5:09 am EST
Unexpected Wet Regime Develops Across Australia
11/15/2023, 12:30 pm EST
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Fig. 1-4: The mega-cluster ensemble “most likely” rainfall anomaly forecast for South America through the next 15 days and the 6-10-day upper air forecast.

Discussion: Most evident in the 6-10-day period, the subtropical ridge delivering a hot and mostly dry 1-5-day forecast (Fig. 1) splits in the 6-10-day period (Fig. 2) to allow tropical moisture to shift across Central Brazil (Fig. 3) in a forecast change. In the 11-15-day period, Central Brazil trends wetter for the same reason (Fig. 4).

In Australia, an unexpectedly wetter than normal weather pattern is indicated for the second half of November (Fig. 5). South-central Australia is wet this week followed by north and northeast continent rains next week. In the extended range, much of the northern half of Australia is wet. The 24-hour rainfall change indicates the wettest adjustment to the forecast is across Queensland (Fig. 6).

Fig. 5-6: ECM ENS rainfall anomaly forecast across Australia for the next 15 days and the 24-hour forecast change.