Meteorological indices for potential occurrence of waterspout/tornado in Hong Kong

Assessment of the potential occurrence of waterspouts and tornadoes in Hong Kong would be crucial in the timely alerting of these hazardous systems. This system provides for the first time a study of the meteorological parameters that may be useful to have an early hinting of the occurrence of such meteorological phenomena in Hong Kong. It turns out that supercell composite parameter (SCP) based on sounding data could be useful in the assessment of relatively strong tornado systems. However, an early assessment of waterspout remains difficult. In particular, bulk Richardson number (BRN) may be a useful indicator, as demonstrated in two examples of waterspouts in Hong Kong, but the indicator itself may not be conclusive and it also has signals for rainstorms in Hong Kong. The usefulness of Szilagyi waterspout nomogram will also be discussed.