As the 2023 tropical season in the Northern Hemisphere draws to a close, it is timely to consider how this year’s activity stacks up. This year has seen a very strong El Nino: this usually has the effect of supressing Atlantic hurricane activity and enhancing Pacific typhoon activity.
The figure on the left below shows the distribution of the number of hurricanes in the Atlantic over the past 10 El Nino years and 2023 in yellow. We can see that 2023 was a year well above the average activity for all Atlantic tropical storms and hurricanes. It is likely that unprecedented sea surface temperatures observed in the Atlantic are partly responsible for this higher than average activity.
The activity in the Nnorth West Pacific is shown on the right in the plot below, again contrasting 2023 against the last 10 El Nino years. 2023 has the lowest activity in all categories when compared against the past 10 El Nino years. The Pacific was also warmer than average this year, partly owing to the El Nino conditions, however this did not translate into a more active typhoon season. Although more work is required to understand the causes of this depressed typhoon activity it is likely that high wind shear or low levels of humidity were present inhibiting the formation of tropical cyclones in the Pacific.
