Search Results

You are looking at 1 - 5 of 5 items for :

  • Author or Editor: Zhiyong Meng x
  • Weather and Forecasting x
  • Refine by Access: All Content x
Clear All Modify Search
Zhiyong Meng
and
Dan Yao

Abstract

On 21 July 2012, severe wind damage occurred in Beijing, China, during a heavy rainfall event. Through a damage survey that had the most detailed information in all of the published tornado damage surveys so far in China, this work showed significant evidence that the wind damage was caused by a mesocyclonic tornado rated as a category 3 storm on the enhanced Fujita scale (EF3) that was observed by people but of which not a single picture was taken. This was the first tornado ever reported or documented in Beijing. The most influential evidence indicating a tornado included a narrow damage swath 30–400 m wide and ~10 km long and convergent surface winds at multiple places along the swath. The radar analyses examined here show that the tornado was embedded in a strong mesocyclone. The initial linear and later sinusoidal tornado track was likely due to the intensification and expansion of the mesocyclone. The location, timing, and intensity variation of the wind damage were precisely collocated with those of a tornadic vortex signature. Descending reflectivity cores as well as their associated jetlets and counterrotating vortices were detected both before tornadogenesis and prior to the reintensification of the tornado damage. A tornadic debris signature was also detected in the later stages of the tornado. Compared to the U.S. climatology of forecast parameters for different storm categories, this storm developed in an environment that was favorable for the formation of supercells or weakly tornadic supercells rather than significantly tornadic supercells.

Full access
Yunji Zhang
,
Zhiyong Meng
,
Fuqing Zhang
, and
Yonghui Weng
Full access
Yunji Zhang
,
Zhiyong Meng
,
Fuqing Zhang
, and
Yonghui Weng

Abstract

The practical predictability of tropical cyclone (TC) intensity in terms of mean absolute forecast error with respect to different conditions at forecast initialization was explored through convection-permitting hindcasts of all Atlantic storms during the 2008–12 hurricane seasons using the Weather Research and Forecasting (WRF) Model. Averaged over a total of 2190 simulations, the day 1–5 performance of these WRF hindcasts was comparable to two operational regional-scale hurricane prediction models used by the National Hurricane Center (NHC) but was slightly inferior to the NHC official forecasts. It was found that the prediction accuracy of TC intensity, both at the initialization time and the targeted forecast hours, was strongly correlated with the TC intensity. On average, for both the WRF hindcasts and the NHC official forecasts, stronger intensities and larger intensity variations led to larger forecast errors. A number of synoptic-scale environmental parameters, such as vertical wind shear, sea surface temperature (SST), and the underlying surface condition (land vs sea), affected the intensity forecast errors of TCs, in part due to their influence on intensity changes, while other thermodynamic environmental parameters, such as moisture and instability, had relatively minor effects. The accuracy of the intensity prediction was also found to be sensitive to the translation speed of the TCs. A moderate TC translation speed of 11–15 knots (kt; 1 kt = 0.51 m s−1) corresponded to the largest intensity errors during forecast lead times less than 60 h, while the slowest translation speed (<7 kt) was associated with the largest errors after the 60-h forecast lead time.

Full access
Jingyi Wen
,
Zhiyong Meng
,
Lanqiang Bai
, and
Ruilin Zhou

Abstract

This study documents the features of tornadoes, their parent storms, and the environments of the only two documented tornado outbreak events in China. The two events were associated with Tropical Cyclone (TC) Yagi on 12 August 2018 with 11 tornadoes and with an extratropical cyclone (EC) on 11 July 2021 (EC 711) with 13 tornadoes. Most tornadoes in TC Yagi were spawned from discrete minisupercells, while a majority of tornadoes in EC 711 were produced from supercells imbedded in QLCSs or cloud clusters. In both events, the high-tornado-density area was better collocated with the K index rather than MLCAPE, and with entraining rather than non-entraining parameters possibly due to their sensitivity to midlevel moisture. EC 711 had a larger displacement between maximum entraining CAPE and vertical wind shear than TC Yagi, with the maximum entraining CAPE better collocated with the high-tornado-density area than vertical wind shear. Relative to TC Yagi, EC 711 had stronger entraining CAPE, 0–1-km storm relative helicity, 0–6-km vertical wind shear, and composite parameters such as an entraining significant tornado parameter, which caused its generally stronger tornado vortex signatures (TVSs) and mesocyclones with a larger diameter and longer life span. No significant differences were found in the composite parameter of these two events from U.S. statistics. Although obvious dry air intrusions were observed in both events, no apparent impact was observed on the potential of tornado outbreak in EC 711. In TC Yagi, however, the dry air intrusion may have helped tornado outbreak due to cloudiness erosion and thus the increase in surface temperature and low-level lapse rate.

Restricted access
Zhiyong Meng
,
Lanqiang Bai
,
Murong Zhang
,
Zhifang Wu
,
Zhaohui Li
,
Meijuan Pu
,
Yongguang Zheng
,
Xiaohua Wang
,
Dan Yao
,
Ming Xue
,
Kun Zhao
,
Zhaoming Li
,
Siqi Peng
, and
Liye Li

Abstract

An EF4 supercellular tornado hit Funing County, Yancheng, Jiangsu Province, China, from about 1410 to 1500 local standard time 23 June 2016, causing 98 fatalities and 846 injuries. It was the deadliest tornado in the past 40 years in China. This paper documents the storm environment, evolution of the radar signatures, real-time operational tornado warning services, and the damage distribution during this event. The tornado was spawned from a supercell that developed ahead of an upper-level trough extending southwestward from a low pressure vortex in northeast China and dissipated following the occlusion of the tornado vortex. The radar-based rotational velocity of the mesocyclone peaked at 42.2 m s−1. The strength of the tornado vortex signature (gate-to-gate azimuthal radial velocity difference) peaked at 84.5 m s−1. Surface observations at 1-min intervals from a mesoscale network of in situ surface weather stations revealed the surface wind pattern associated with the mesocyclone, such as convergent and rotational flows. The tornado formed after the peak updraft strength of the supercell, producing a damage swath that was 34.5 km long and with a maximum width of 4.1 km. The review of the tornado warning process for this event reveals that there is much work to be done to develop operational tornado forecast and warning services for China.

Full access