The ECMWF seasonal forecast updated yesterday (May 5th) for the next 7-months. The outlook for La Nina looks solid with colder than the mean SSTs in the tropical Pacific centered along 120°W. The Atlantic tropics remain much warmer than climatological mean by up to 1°C. This sets the stage for an active Atlantic hurricane season, which every forecast outlooks suggests — some going with hyperactive. This is a dynamical model system, and there is a bias whenever discussing long-range modeling solutions. Nevertheless, the signal is “significant” enough to raise alarms about extremely active Atlantic tropics during the peak of the season (September).

Hurricanes drop rainfall and lots of it in the tropics along their tracks. The seasonal precipitation anomaly (Aug-Oct) shows highest anomalously positive precipitation over the Caribbean and along the typical tracks of storms from the MDR into the Lesser Antilles.