As the polar region turns sharply colder due to loss of sunlight mid-to-late autumn, cold air is swept across an increase in open ocean water (due to a constricting polar ice cap) that leads to advection snows bringing above normal snowfall to the northern continents most notably Northern Russia.

The unexpected quiet period across the tropical/subtropical North Atlantic basin may be about to end. Tropical waves are stronger as they move across tropical Africa and into the eastern North Atlantic tropics. However, the ECM ENS 15-day rainfall forecast indicates extreme rain across tropical Africa as tropical waves and their attendant convective energy are about to intensify dramatically.

As early September arrives, most striking, is the cool weather set-up in the Midwest/East U.S. centered on the 6-10/8-12-day period. At that time, both the arctic oscillation (AO) and North Atlantic oscillation (NAO) shift to negative phase supporting a high latitude blocking ridge and amplified polar vortex centered on Ontario and the Great Lakes.

Climate Impact Company cut the North Atlantic seasonal TC forecast to 17 storms, 11 hurricanes, and 6 intense hurricanes on Aug. 27. The North Atlantic environment is forecast to be exceptionally supportive of above too much above normal activity for the next 10 weeks. Operational (model) forecasts doubt that level of activity. The CIC forecast vs. climatology is a good range of expectations for SEP, OCT, and NOV 2024.