A key climate diagnostic identifying tropical cyclone potential across the tropical/subtropical North Atlantic basin at early onset of the season is the relative humidity or available moisture in the middle atmosphere. Above to much above normal available moisture, common during the past 25 years of seasonal uptick in North Atlantic activity signals above normal activity ahead. The early 2020 season available moisture is buoyant across the Gulf of Mexico and outer tropical basin signaling an active season ahead!

During 2007 to 2019 the NAO pattern has been negative throughout the summer season except 2013 and 2018. A +NAO pattern appears to be setting up for summer 2020. Implied is a ridge pattern capable of producing anomalous warmth and possible drought on northern Europe to Western Russia and periodic very hot weather pulses in the Central U.S.

Evolution of La Nina during negative phase of the Indian Ocean Dipole suggest that the attendant convection patterns associated with this regime will be stronger and have a more dramatic impact on global La Nina climate. Both strength of La Nina climate anomalies could be stronger and La Nina could linger in 2021.