Fig. 1: North Atlantic basin SSTA and trend.
Discussion: The North Atlantic basin SSTA is +0.23C and slightly cooler (-0.07C) during the past week (Fig. 1). The complexion of the North Atlantic SSTA is nearly opposite of this time last year. The North Atlantic tropics/subtropics are very close to normal in June 2021 while last year SSTA was somewhat warmer than normal. Conversely, the central North Atlantic is quite warm right now while last year the North Atlantic Warm Hole (NAWH) was shifted farther south causing cool SSTA east and northeast of Bermuda. Waters off the Northeast U.S. Coast are warm (and warming) whereas this region was quite cool 1 year ago. The North Atlantic tropics/subtropics are normally supportive of tropical cyclone development given near normal SSTA.
The lack-luster marginal anomalous warm North Atlantic basin is characteristic of increasing incidence of normal Atlantic multi-decadal oscillation (AMO) in 6 of the past 11 years (Fig. 2). The analog years some brief warming for AUG/SEP/OCT 2021 is ahead but not nearly as robust as last year
Fig. 2: The Atlantic multi-decadal oscillation is neutral which is more common in recent years during quarter 2. Analogs indicate brief warming of AMO for peak of tropical cyclone season.
Currently, the North Atlantic basin is ALL CLEAR. A tropical wave in the central tropical North Atlantic shifts westward and should weaken once reaching the Caribbean Sea (Fig. 3). The remains of former Tropical Storm Claudette are southeast of Nova Scotia accelerating northeastward and dissipating. In northern Mexico evidence of a developing convective phase of North America Monsoon is evident.
Fig. 3: Satellite view of the North Atlantic basin.