scholarly journals Importance of Terrain Representation in Simulating a Stationary Convective System for the July 2017 Northern Kyushu Heavy Rainfall Case

SOLA ◽  
2018 ◽  
Vol 14 (0) ◽  
pp. 153-158 ◽  
Author(s):  
Tetsuya Takemi
Keyword(s):  
Heavy Rainfall ◽  
Convective System ◽  
Terrain Representation

Analysis of the Evolution of a Meiyu Frontal Rainstorm Based on Doppler Radar Data Assimilation

2020 ◽  
Author(s):  
Hongli Li ◽  
Yang Hu ◽  
Zhimin Zhou
Keyword(s):  
Heavy Rainfall ◽  
Doppler Radar ◽  
Heavy Precipitation ◽  
Radar Data ◽  
Economic Losses ◽  
Mature Stage ◽  
Convective System ◽  
Low Level ◽  
Sufficient Energy ◽  
Study Results

<p>During the Meiyu period, floods are prone to occur in the middle and lower reaches of the Yangtze River due to the highly concentrated and heavy rainfall, which caused huge life and economic losses. Based on numerical simulation by assimilating Doppler radar, radiosonde, and surface meteorological observations, the evolution mechanism for the initiation, development and decaying of a Meiyu frontal rainstorm that occurred from 4th to 5th July 2014 is analyzed in this study. Results show that the numerical experiment can well reproduce the temporal variability of heavy precipitation and successfully simulate accumulative precipitation and its evolution over the key rainstorm area. The simulated “rainbelt training” is consistent with observed “echo training” on both spatial structure and temporal evolution. The convective cells in the mesoscale convective belt propagated from southwest to northeast across the key rainstorm area, leading to large accumulative precipitation and rainstorm in this area. There existed convective instability in lower levels above the key rainstorm area, while strong ascending motion developed during period of heavy rainfall. Combined with abundant water vapor supply, the above condition was favorable for the formation and development of heavy rainfall. The Low level jet (LLJ) provided sufficient energy for the rainstorm system, and the low-level convergence intensified, which was an important reason for the maintenance of precipitation system and its eventual intensification to rainstorm. At its mature stage, the rainstorm system demonstrated vertically tilted structure with strong ascending motion in the key rainstorm area, which was favorable for the occurrence of heavy rainfall. In the decaying stage, unstable energy decreased, and the rainstorm no longer had sufficient energy to sustain. The rapid weakening of LLJ resulted in smaller energy supply to the convective system, and the stratification tended to be stable in the middle and lower levels. The ascending motion weakened correspondingly, which made it hard for the convective system to maintain.</p>

Predecessor Rain Events ahead of Tropical Cyclones

2010 ◽  
Vol 138 (8) ◽  
pp. 3272-3297 ◽  
Author(s):  
Thomas J. Galarneau ◽  
Lance F. Bosart ◽  
Russ S. Schumacher
Keyword(s):  
Tropical Cyclones ◽  
Heavy Rainfall ◽  
The United States ◽  
Synoptic Climatology ◽  
Convective System ◽  
Low Level ◽  
Rain Events ◽  
Tropical Moisture ◽  
Baroclinic Zone

Abstract Twenty-eight predecessor rain events (PREs) that occurred over the United States east of the Rockies during 1995–2008 are examined from a synoptic climatology and case study perspective. PREs are coherent mesoscale regions of heavy rainfall, with rainfall rates ≥100 mm (24 h)−1, that can occur approximately 1000 km poleward of recurving tropical cyclones (TCs). PREs occur most commonly in August and September, and approximately 36 h prior to the arrival of the main rain shield associated with the TC. A distinguishing feature of PREs is that they are sustained by deep tropical moisture that is transported poleward directly from the TC. PREs are high-impact weather events that can often result in significant inland flooding, either from the PRE itself or from the subsequent arrival of the main rain shield associated with the TC that falls onto soils already saturated by the PRE. The composite analysis shows that on the synoptic-scale, PREs form in the equatorward jet-entrance region of a 200-hPa jet on the western flank of a 925-hPa equivalent potential temperature ridge located east of a 700-hPa trough. On the mesoscale, PREs occur in conjunction with low-level frontogenetical forcing along a baroclinic zone where heavy rainfall is focused. A case study analysis was conducted of a PRE ahead of TC Erin (2007) that produced record-breaking rainfall (>250 mm) from southern Minnesota to Lake Michigan. This analysis highlighted the importance of frontogenetical forcing along a low-level baroclinic zone in the presence of deep tropical moisture from TC Erin in producing a long-lived, quasi-stationary mesoscale convective system.

scholarly journals Numerical Simulations and Analysis of June 16, 2010 Heavy Rainfall Event over Singapore Using the WRFV3 Model

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
B. H. Vaid
Keyword(s):  
Numerical Simulations ◽  
Heavy Rainfall ◽  
Global Analysis ◽  
Heavy Rain ◽  
Rainfall Event ◽  
Cumulus Parameterization ◽  
Heavy Rainfall Event ◽  
Convective System ◽  
Rain Event ◽  
Simulated Precipitation

The Numerical Simulations of the June 16, 2010, Heavy Rainfall Event over Singapore are highlighted by an unprecedented precipitation which produced widespread, massive flooding in and around Singapore. The objective of this study is to check the ability of Weather Research Forecasting version 3 (WRFV3) model to predict the heavy rain event over Singapore. Results suggest that simulated precipitation amounts are sensitive to the choice of cumulus parameterization. Various model configurations with initial and boundary conditions from the NCEP Final Global Analysis (FNL), convective and microphysical process parameterizations, and nested-grid interactions have been tested with 48-hour (June 15–17, 2010) integrations of the WRFV3. The spatial distributions of large-scale circulation and dynamical and thermodynamical fields have been simulated reasonably well in the model. The model produced maximum precipitation of ~5 cm over Changi airport which is very near to observation (6.4 cm recorded at Changi airport). The model simulated dynamic and thermodynamic features at 00UTC of June 16, 2010, lead to understand the structure of the mesoscale convective system (MCS) that caused the extreme precipitation over Singapore. It is observed that Singapore heavy rain was the result of an interaction of synoptic-scale weather systems with the mesoscale features.

scholarly journals A mesoscale convective system trapped along the Spanish Mediterranean Coast

2006 ◽  
Vol 7 ◽  
pp. 153-156 ◽  
Author(s):  
J. M. Sánchez-Laulhé
Keyword(s):  
Convective Instability ◽  
Heavy Rainfall ◽  
Vertical Wind Shear ◽  
Mesoscale Convective System ◽  
Precipitable Water ◽  
Mediterranean Coast ◽  
Convective System ◽  
Convective Storm ◽  
Low Level ◽  
Mesoscale Convective

Abstract. This paper describes the evolution of a mesoscale convective system (MCS) developed over the Alboran Sea on 7 February 2005, using surface, upper-air stations, radar and satellite observations, and also data from an operational numerical model. The system developed during the night as a small convective storm line in an environment with slight convective instability, low precipitable water and strong low-level vertical wind shear near coast. The linear MCS moved northwards reaching the Spanish coast. Then it remained trapped along the coast for more than twelve hours, following the coast more than five hundred kilometres. The MCS here described had a fundamental orographic character due to: (1) the generation of a low-level storm inflow parallel to the coast, formed by blocking of the onshore flow by coastal mountains and (2) the orientation of both the mesoscale ascent from the sea towards the coastal mountains and the midlevel rear inflow from the coastal mountains to the sea. The main motivation of this work was to obtain a better understanding of the mechanisms relevant to the formation of heavy rainfall episodes occurring at Spanish Mediterranean coast associated with this kind of stationary or slowly moving MCSs.

How Were the Eastward-Moving Heavy Rainfall Events from the Tibetan Plateau to the Lower Reaches of the Yangtze River Enhanced?

2021 ◽  
Vol 34 (2) ◽  
pp. 607-620
Author(s):  
Yang Zhao ◽  
Deliang Chen ◽  
Yi Deng ◽  
Seok-Woo Son ◽  
Xiang Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Yangtze River ◽  
Heavy Rainfall ◽  
Diabatic Heating ◽  
Convective Motion ◽  
Convective System ◽  
The Tibetan Plateau ◽  
The Yangtze River ◽  
Rainfall Events ◽  
Heavy Rainfall Events

AbstractThis study investigates eastward-moving summer heavy rainfall events in the lower reaches of the Yangtze River (LRYR), which are associated with the Tibetan Plateau (TP) vortices. On the basis of rainfall data from gauges and additional atmospheric data from ERA-Interim, the dynamic and thermodynamic effects of moisture transport and diabatic heating are estimated to determine the physical mechanisms that support the eastward-moving heavy rainfall events. As the rainband moves eastward, it is accompanied by anomalous cyclonic circulation in the upper and middle troposphere and enhanced vertical motion throughout the troposphere. In particular, the rainfall region is located in the fore of the upper-level trough, which is ideal for baroclinic organization of the convective system and further development of the eastward-moving vortex. The large atmospheric apparent heat source (Q1) also contributes for lifting the lower-level air into the upper atmosphere and for enhancing the low-level convective motion and convergence during the heavy rainfall process. Piecewise potential vorticity inversion further verifies the crucial role that the diabatic heating played in developing the anomalous geopotential height favorable for the enhanced rainfall. The combined action of the dynamic and thermodynamic processes, as well as the rich moisture supply from the seas, synergistically sustained and enhanced the eastward-moving rainfall.

scholarly journals Rainfall events and Hailstorms Analysis Program (RHAP)

2006 ◽  
Vol 7 ◽  
pp. 205-213 ◽  
Author(s):  
M. Ceperuelo ◽  
M. C. Llasat ◽  
T. Rigo
Keyword(s):  
Heavy Rainfall ◽  
Rapid Development ◽  
Maximum Activity ◽  
Convective Precipitation ◽  
Heavy Rainfall Event ◽  
Convective System ◽  
Analysis Program ◽  
Meteorological Model ◽  
Rainfall Events ◽  
Stratiform Precipitation

Abstract. RHAP (Rainfall events and Hailstorms Analysis Program) is a new tool designed for analysing rainfall events and hailstorms. The aim of this contribution is to present the RHAP tool, which is under development, and its application to different hailstorms and rainfall episodes. The program assimilates multiple data bases (meteorological radar, meteorological model outputs, radiosondes and surface observations) with the purpose to get better event reanalysis. It is based on Storm Cell Identification and Tracking Algorithm (SCIT) with an improved version of the method, and also on a new 2-D algorithm which automatically identifies and classifies the precipitation systems distinguishing between Mesoscale Convective Systems, Multicellular systems, Isolated convection, Stratiform precipitation and Convective precipitation embedded in stratiform precipitation. These two methods allow to obtain the 2-D and 3-D features of the precipitation system like top height of the cells, maximum reflectivity, Vertical Integrated Liquid content (VIL) and VIL density (VILD), kinetic energy, severe hail probability (SHP), number of 3-D cells exceeding a given threshold, Z/R relations,... that are useful to analyse both heavy rainfall and hail events. As application, two events produced on NE Spain are discussed: the heavy rainfall event recorded on 6 September 2004, characterised by a great number of cells that crossed the affected area and that had a maximum activity associated to high values of VIL(37.5 kg/m2), Zmax (54 dBZ) and SHP (73%); and the hail event produced on 29 August 2004, with a rapid development of the convective system and with hail observations in surface when the following thresholds were exceeded: Zmax=54 dBZ, VIL=25 kg/m2 and SHP=63%.

scholarly journals Dominant processes of extreme rainfall-producing mesoscale convective system over southeastern Korea: 7 July 2009 case

2015 ◽  
Vol 3 (10) ◽  
pp. 6459-6489
Author(s):  
J.-H. Jeong ◽  
D.-I. Lee ◽  
C.-C. Wang ◽  
I.-S. Han
Keyword(s):  
Metropolitan Area ◽  
Heavy Rainfall ◽  
Deep Convection ◽  
Mesoscale Convective System ◽  
Extreme Rainfall ◽  
Cold Pool ◽  
Convective System ◽  
Frontal Surface ◽  
Mesoscale Convective ◽  
Outflow Boundary

Abstract. An extreme rainfall-producing mesoscale convective system (MCS) associated with the Changma front in southeastern Korea was investigated using observational data. This event recorded historic rainfall and led to devastating flash floods and landslides in the Busan metropolitan area on 7 July 2009. The aim of the present study is to analyze and better understand the synoptic and mesoscale environment, and the behavior of quasi-stationary MCS causing extreme rainfall. Synoptic and mesoscale analyses indicate that the MCS and heavy rainfall occurred association with a stationary front which resembled a warm front in structure. A strong southwesterly low-level jet (LLJ) transported warm and humid air and supplied the moisture toward the front, and the air rose upwards above the frontal surface. As the moist air was conditionally unstable, repeated upstream initiation of deep convection by back-building occurred at the coastline, while old cells moved downstream parallel to the convective line with training effect. Because the motion of convective cells nearly opposed the backward propagation, the system as a whole moved slowly. The back-building behavior was linked to the convectively produced cold pool and its outflow boundary, which played an essential role in the propagation and maintenance of the rainfall system. As a result, the quasi-stationary MCS caused a prolonged duration of heavy rainfall, leading to extreme rainfall over the Busan metropolitan area.

Impact of the Korea Rapid Developing Thunderstorms (K-RDT) product nudging to the convective parameterization over the Korean Peninsula

2020 ◽  
Author(s):  
Namgu Yeo ◽  
Eun-Chul Chang ◽  
Ki-Hong Min
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Deep Convection ◽  
Weather Prediction ◽  
Model System ◽  
Prediction Skill ◽  
Precipitation Forecast ◽  
Small Scale ◽  
Convective System ◽  
Convective Cells

<p>In this study, Korea Rapid Developing Thunderstorms (K-RDT) product from geostationary meteorological satellite which represents developing stage of convective cells is nudged to the Simplified Arakawa Schubert (SAS) deep convection scheme using a simple nudging technique in order to improve prediction skill of a heavy rainfall caused by mesoscale convective system over South Korea in the short-term forecast. Impact of the K-RDT information is investigated on the Global/Regional Integrated Model system (GRIMs) regional model program (RMP) system. For the selected heavy rainfall cases, the control run without nudging and two nudging experiments with different nudging period are performed. Although the simulated precipitations in the nudging experiments tend to depend on the distribution of convective cells detected in the K-RDT algorithm, the nudging experiment shows improved precipitation forecast than the control experiment. Particularly, the experiment with nudging for longer time produces better prediction skill. The results present that the small-scale convective cells from the K-RDT which are detected with a 1-km resolution have clear impacts to large-scale atmospheric fields. Therefore, it is suggested that utilizing small-scale information of convective system in the numerical weather prediction can have critical impact to improve forecast skill when the model system, which cannot properly represent sub-grid scale convections.</p>

Distant Effects of a Recurving Tropical Cyclone on Rainfall in a Midlatitude Convective System: A High-Impact Predecessor Rain Event*

2011 ◽  
Vol 139 (2) ◽  
pp. 650-667 ◽  
Author(s):  
Russ S. Schumacher ◽  
Thomas J. Galarneau ◽  
Lance F. Bosart
Keyword(s):  
Heavy Rainfall ◽  
Convective Available Potential Energy ◽  
Precipitation Amount ◽  
High Impact ◽  
Mature Stage ◽  
Northern Great Plains ◽  
Convective System ◽  
Rain Event ◽  
Control Simulation ◽  
Tropical Moisture

Abstract Recent research has identified predecessor rain events (PREs), which are mesoscale regions of heavy rainfall that occur ∼1000 km poleward and downshear of recurving tropical cyclones (TCs). PREs typically occur 24–36 h prior to the arrival of the main rain shield associated with the TC, and frequently result in damaging flooding. A distinguishing feature of a PRE is that it is enhanced by a broad region of deep tropical moisture directly associated with the TC that is transported well poleward ahead of the TC. This study will quantify the effects of the tropical moisture from one TC on a record-breaking rain and flood event over the northern Great Plains and southern Great Lakes region on 18–19 August 2007. In this event, which occurred ahead of TC Erin, a southerly stream of deep tropical moisture (precipitable water values >50 mm) moved poleward and intersected a northwest–southeast-oriented quasi-stationary baroclinic zone beneath the equatorward entrance region of an upper-level jet streak. A slow-moving mesoscale convective system (MCS) developed and produced widespread heavy rainfall, with local amounts exceeding 380 mm that resulted in historic flooding in Minnesota and Wisconsin. Observations and numerical simulations using the Advanced Research Weather Research and Forecasting model (ARW-WRF) indicate that low-level frontogenesis was maximized during the overnight hours of 19 August 2007 and provided the forcing for vigorous ascent during the mature stage of the PRE. A control simulation, which included the poleward transport of TC Erin-related moisture, reproduced the extreme rainfall amounts, although the simulated rainfall was displaced from where it was observed. A sensitivity simulation in which the moisture associated with TC Erin was removed (referred to as “NOPLUME”) shows reduced convective available potential energy (CAPE) in the inflow region of the PRE and a less vigorous MCS. In all, there was an approximately 50% reduction in the maximum precipitation amount and a 25% reduction in the total precipitation from the control simulation to the NOPLUME run. Or, considered in the context of rainfall enhancement by the Erin-related moisture, there was a near doubling of the maximum amount and a 33% increase in the total rainfall. The extent of these differences underscores the importance of moisture originating from TC Erin in transforming a heavy rain event into a high-impact, record-breaking rain event.

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