The below normal activity in each basin is unusual. The reasons for the below normal activity are under review. In the Northwest Pacific, high-level above normal westerly wind shear across the tropics has limited hurricane development while stronger than normal low-level trade winds have suppressed activity in the deep tropics of the Northeast Pacific and North Atlantic.

A review of the seasonal hurricane activity predictors is mixed with warm SSTA in the main development region (MDR) supportive of hurricane development while fast trade winds suppressing tropical development have been a significant inhibiting factor.

Currently, the Indian Ocean dipole is in weak positive phase. The western basin is 0.32C warmer than the eastern basin identifying the +IOD regime. The IOD trend of recent weeks is to drift into the weak positive phase. The IOD forecast was a shift into the negative phase for the last third of 2024. Due to the recent rewarming of the western tropical North Atlantic, the -IOD forecast remains, but is generally weaker and not all models project -IOD.

Cooling of the equatorial Atlantic has pushed the ITCZ farther north and into the faster than normal trade wind belt. Saharan Dust has shifted westward through the trade wind belt. These conditions are preventing tropical cyclone activity. Due to these conditions, the western North Atlantic basin becomes the most favored location for tropical cyclone development.