Rapid-Scan and Polarimetric Phased-Array Radar Observations of a Tornado in the Pearl River Estuary

The strong destructive winds during tornadoes can greatly threaten human life and destroy property.The increasing availability of visual and remote observations,especially by Doppler weather radars,is of great value in understanding tornado formation and issuing warnings to the public.In this study,we present the first documented tornado over water detected by a state-of-the-art dual-polarization phased-array radar(dual-PAR)in China.In contrast to new-generation weather radars,the dual-PAR shows great advantages in tornado detection for its high spatial resolution,reliable polarimetric variables,and rapid-scan strategy.The polarimetric signature of copolar cross-correlation coefficient with anomalously low magnitude appears to be effective for verifying a tornado and thus is helpful for issuing tornado warnings.The Guangdong Meteorological Service has been developing an experimental X-band dual-PAR network in the Pearl River Delta with the goal of deploying at least 40 advanced dual-PARs and other dual-polarization weather radars before 2035.This network is the first quasi-operational X-band dual-PAR network with unprecedented high coverage in the globe.With such high-performance close-range PARs,efficient operational nowcasting and warning services for small-scale,rapidly evolving,and damaging weather(e.g.,tornadoes,localized heavy rainfall,microbursts,and hail)can be expected.

A Brief Discussion on the High-impact Cold-season Tornado Outbreak During 10-11 December 2021 in the United States

An outbreak of powerful tornadoes tore through multiple states in the central and southern United States from 10 to 11 December 2021.It is claimed the deadliest tornado outbreak that has taken place on December days.The National Oceanic and Atmospheric Administration had confirmed 66 tornadoes as of 21 December,producing at least 90 fatalities.Most tornadoes occurred at night and thus they were difficult to be visually located,which directly increases the risk for local residents.Two violent nighttime tornadoes were rated category 4 on the enhanced Fujita scale(EF4).Although a high death toll was caused during this event,the operational service actually presented an excellent performance.This tornado outbreak has aroused extensive discussion from both the public and the research community in China.This paper presents a brief discussion on the formation environment and warning services of the tornado outbreak.Recall the deadliest violent tornado in the past 45 years in China,the radar-based tornadic vortex signatures at the locations with EF4 damages show a comparable strength with those in the current cases.Some views on the tornado warning issuance and receiving and damage surveys in China are also presented.