La Nina/warm Atlantic multi-decadal oscillation support BIG year for hurricanes in the tropical North Atlantic
Fig. 1: The NMME global SSTA forecast for JUN/JUL/AUG 2020 reveals La Nina risk coupled with a warm North Atlantic which supports a busy hurricane season in the tropical North Atlantic.
Discussion: NOAA, the Australian Bureau of Meteorology and European Center for Medium-range Forecasts (ECMWF) are not forecasting La Nina in 2020. However, three leading global models (NMME, CFS V2 and GFDL) each project La Nina by JUN/JUL/AUG 2020. The global models also reveal a very warm North Atlantic surface (positive phase of the Atlantic multi-decadal oscillation). The La Nina/+AMO combination is very supportive of a busy hurricane season in the North Atlantic tropics. The La Nina is well-correlated with a low shear environment of the upper levels of the tropical atmosphere in the North Atlantic while +AMM supplies plenty of ocean heat. Surprisingly, La Nina/+AMM combinations are rare occurring only twice in the past 30 years (1998 and 2010). In 2010 there were 12 hurricanes and in 1998 a total of 10 hurricanes formed in the North Atlantic basin. The normal amount of hurricanes in one season is 7. Close monitoring of ENSO in regard to a potentially dangerous 2020 tropical cyclone season in the North Atlantic is warranted!