The influences of grouped anticyclonic eddies (AEs) in the ocean on the intensity of tropical cyclone (TC) in the atmosphere are investigated in the present study. The research was carried out using numerical methods taking the development of TC Hato (2017) in the northern South China Sea (SCS) as an example. Three AEs were observed, one at the TC track (defined as the inner area) and the other two in the south of the TC center (defined as the outer area), at about three times the radius of maximum wind speed. The results show that the outer AEs suppress TC development, but the inner AEs greatly favor TC development. This opposite influence primarily results from the different responses of TC secondary circulation to the AE‐induced local sea surface warm anomaly in the inner and outer areas. The outer AE triggers a low sea level pressure anomaly and convergent wind toward the AE, which weakens TC inflow at the lower layers and further weakens TC secondary circulation. Consequently, the energy conversion from ocean heat energy to TC kinetic energy is decreased by the weakened TC secondary circulation. The AE in the outer area also extends the TC eyewall, weakens the TC warm core, and increases the outer precipitation. As a result, the TC intensity is weakened. The inner AE causes opposite changes in TC secondary circulation, eyewall, warm core, and outer precipitation, so that favors TC development. These results provide evidence for the suppression effect of the outer AEs on TC development, providing a new perspective toward improving TC intensity forecasts.

The relationship between sea surface temperature (SST) and tropical cyclone (TC) intensity change exhibits a strong dependence on the current TC intensity. Using western North Pacific TC observations from 1982 to 2018, a threshold SST (TSST) is identified as the SST required to maintain TC intensity. TSST increases with TC intensity, with TCs intensifying and weakening when SST is higher and lower than TSST, respectively. Across the dataset, mean TC intensity change is proportional to the difference between SST and TSST. This study also formulates an equation to quantify TC intensity change using SST and current TC intensity, which replicates 99.46% of the mean observed TC intensity changes. This equation could serve as an alternative to the linear regression‐based relationship between SST and TC intensity change that is widely used in statistical‐dynamical intensity models, thereby improving intensity forecasts.

Tropical cyclones have resulted in casualties and economic losses in the areas surrounding the Bay of Bengal (BoB). Thus, a comprehensive investigation of these tropical cyclones holds vital implications for disaster preparedness and mitigation. This paper compares the occurrence of storms in the last two decades, i.e., 2002–2011 and 2012–2021, and results reveal that such storms exhibited predominantly a northwesterly track towards the northwestern BoB, with a severer intensity but equal total storm frequencies. Over the past decade, a southeast-northwest pathway (SNP) was identified, demonstrating a higher incidence of severe tropical cyclones (STC, with lifetime maximum intensity ≥ 64 knots) over the BoB. Further analysis of the changes in the environmental conditions between these two decades indicates that a southeasterly anomaly in the steering flow contributed to the formation of the SNP. During the same period, the more favorable oceanic conditions during the last decade, including higher sea surface temperatures, a greater upper ocean heat content, a thicker warm water layer, and a thicker barrier layer beneath the SNP, favored the development of these storms by providing more heat energy to the storms. The atmospheric conditions, including increased air-sea heat fluxes, moisture, and instability within the lower troposphere, as well as reduced vertical wind shear, facilitated the development of convection within these storm systems. These favorable conditions improved the potential for storm development into STCs and elevated the risk of the northwestern BoB being impacted by more destructive storms.