In Subtropical Western North Pacific Typhoons, Prior Along‐Track Marine Heatwave Contact Is Associated With Rapid Intensification

Abstract

Annual marine heatwave (MHW) days more than tripled in the subtropical western North Pacific between 1982–2002 and 2003–2023. Previous studies mainly examined concurrent MHW conditions, often using coarser‐resolution sea surface temperature (SST) analyses. Less attention has been given to MHW exposure earlier along individual storm tracks before rapid intensification (RI, 30 kt strengthening in 24 hr). Using a storm‐specific anchor, we matched Digital Typhoon tracks to longer‐record and higher‐resolution daily SST analyses. In the longer record, RI occurred in 9.09% of storms with prior contact and 3.52% without it. The adjusted odds ratio was 2.72 after accounting for storm intensity, motion, duration, genesis location, year, and season. In the higher‐resolution analysis, RI occurred in 12.24% of storms with prior contact and 4.59% without it, with an adjusted odds ratio of 3.36. The association remained positive after environmental controls and across RI‐threshold and bathymetric sensitivities, but was weaker and statistically uncertain in the low‐latitude subdomain. Among RI storms with prior contact, median maximum MHW event duration was 25.5 days in the longer‐record analysis and 17 days in the higher‐resolution analysis, while median cumulative storm contact lasted 14.5 and 7 hr, respectively. First contact preceded RI by a median of 38–42 hr. Detrended and moving‐baseline MHW definitions gave weaker, uncertain estimates of 1.84 and 1.51. Across both analyses, RI probability was highest after prior MHW contact, while storms encountering positive SST anomalies that did not meet the MHW criterion showed less consistent differences from neutral conditions.