The ECMWF 14-day MJO forecast indicates an eastward shift away from Australia. The transition indicates gradually less wet risk to Australia (especially the north coast) and a slight increase in wet risk for South America (by mid-month). The influence on the U.S. a shift from short-term warmth to a cooler medium-range forecast.

A significant predictor for numbers of the most intense storms is the presence of warmer-than-normal deep tropics ocean water as measured by the tropical North Atlantic (TNA) index. During the past 25 years the North Atlantic tropics have typically been somewhat warmer than normal during the core of the tropical cyclone season.

The preliminary outlook indicates MAY-SEP 2021 is hotter than last year as the average of the U.S. cities CDD forecast is about 112% of the 30-year normal compared to just-under 109% last year. Meteorological summer (JUN/JUL/AUG) is not quite as hot as last year.

Last week southern oscillation index returned to weak positive phase and trade winds off the northwest coast of South America also returned. As a result, the increased trade winds up-welled cool waters to cause all Nino SSTA regions to fall to within La Nina thresholds. However, the subsurface at 75+ meters continue to warm and subsurface cool water supply to sustain La Nina is steadily losing amplitude.