A waterspout was sighted in the offshore waters of Hong Kong in mid-October 2025, the second-latest occurrence of this weather phenomenon in a single year since 1959. Due to the close proximity of the phenomenon to Lamma Island in Hong Kong, detailed sighting information and photographs of the waterspout are available for analysis. This paper investigates the meteorological background of the event, the stability of the atmosphere, and weather radar images from two dual-polarization weather radar stations within the territory to determine the type and intensity of the observed waterspout and its formation mechanism. At that time, the atmosphere was rather unstable, with high values for CAPE and bulk Richardson number, along with an upper-level divergence area that provided updraft momentum for convective development. Detailed observations from these weather radar images showed that the waterspout was a rather weak system with relatively low radar reflectivity and generally weak Doppler velocities, although the velocity signatures, such as Doppler velocity couplets, and azimuthal shear were quite clear. The potential for an operational 2-kilometer ensemble prediction system (EPS) from the Hong Kong Observatory to indicate a favorable environment for waterspout development was also investigated. While the EPS cannot be expected to resolve the waterspout problem or reproduce its exact location and timing, it can capture weak low-level cyclonic anomalies and convergences near Lamma Island that would provide favorable conditions for the formation of waterspouts and are broadly consistent with the observed mesoscale environment.
Chan et al. (Wed,) studied this question.