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... the other end of the supercell spectrum are the so-called High-(or Heavy-) Precipitation (HP) supercells (Fig. 2). Whereas LP storms have little or no precipitation (and, hence, low re- flectivity) within their mesocyclones, HP storms are characterized by substantial precipitation within their mesocyclonic circulations. When HP storms have a recognizable hook echo (many do not), reflectivities in the hook will be compara- ble to those in the ...
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... The LIMA2 simulation produces a dramatically reduced accumulated hail precipitation on the ground compared to the LIMA1 simulation (3 mm in LIMA2 vs. 15 mm in LIMA1). Although it is not possible to draw conclusions about the amount of hail reaching the ground, the rather restricted location of hail on the ground with the LIMA2 simulation is more in line with the supercell patterns shown in Doswell and Burgess (1993) and Kumjian and Ryzhkov (2008). ...
A full two-moment microphysics parameterization of the LIMA scheme (with LIMA standing for Liquid Ice Multiple Aerosols and hereafter named LIMA v2.0) has been developed and successfully implemented in the Meso-NH cloud-resolving model. The novelty of the scheme is a set of prognostic equations of the number concentration of each precipitating ice category (snow/aggregates, graupel, and hail), in addition to the prediction of the mass mixing ratios. As a result, new microphysical conversion rates are introduced and explicitly computed using the size distributions of the hydrometeors.
The new LIMA v2.0 scheme has been tested for an idealized deep convection case against the original LIMA scheme characterized by an empirical number-concentration–mixing-ratio relationship applied to the precipitating ice. Inclusion of number concentration equations for the snow/aggregates and graupel significantly alters the microphysical structure and dynamical evolution of the simulated supercell. When comparing to the results obtained with the previous version of LIMA, the new v2.0 of the scheme tends to increase the pristine ice mixing ratio; to decrease the other ice hydrometeors by slowing down the growing processes of snow/aggregates, graupel, and hail; and to enhance the feedbacks between raindrops and the ice-phase hydrometeors. This comparison also emphasizes the unreasonable diagnostic approach used to estimate the number concentration of precipitating ice particles in the previous version of the scheme. The new scheme is more efficient at producing earlier raindrops at ground level and reducing hail precipitation.
... As mentioned in Section 1, the devastating storm in Parsa and Bara districts on 31 March 2019 (see Figure 1) is regarded as a tornado. Tornadoes are usually formed in association with supercells (or mesocyclones), which are deep and persistent convective cells (e.g., [33,34] and summarized in [4]). Two factors of strong buoyancy and large vertical wind shear in the lower atmosphere are known to be necessary for the development of mesocyclones. ...
On the evening of 31 March 2019, Parsa and Bara Districts in central Nepal were severely hit by a wind storm which was the first documented tornadic incidence in Nepal.In this paper, we investigate the background of the tornado formation via numerical simulations with the WRF-ARW model. The results show that: (1) a flow situation favorable to the generation of mesocyclones was formed by a combination of local plain-to-mountain winds consisting of warm and humid southwesterly wind in the lower atmosphere and synoptic northwesterly wind aloft over the southern foothills of the Himalayan Mountain range, leading to significant vertical wind shear and strong buoyancy; (2) the generated mesocyclone continuously shed rain-cooled outflow with 600∼800 m depth above the ground into the Chitwan valley while moving southeastward along the Mahabharat Range at the northeastern rim of the Chitwan valley; (3) the cold outflow propagated in the valley, forming a front; and (4) the tornado was generated when this cold outflow passed over the Siwalik Hills bordering the southern rim of the Chitwan valley. At this point, descending flow around a high mountain generated positive vertical vorticity near the ground; blocking by this high mountain and channeling through a mountain pass enhanced updrafts at the front by forming a hydraulic jump. These updrafts amplified the positive vertical vorticity via stretching, and this interaction of the cold outflow with the Siwalik Hills contributed to tornadogenesis. The simulated location and time of the disaster showed generally good agreement with the reported location and time.
... However, a tornado with a wind speed of 51-61 m/s, which belongs to the F2 class on the Fujita scale [77,78], destroys 3% of lightly built buildings and 0.8% of buildings with reinforced foundations. 6. Verification of the proposed theory A common physical-environmental tornado model may be presented as a strongly rotating vertical air column originating in a cumulonimbus thundercloud reaching ES [4,9,18]. Typical for tornadoes, hurricane winds can cause severe building and industrial damage (e.g., [2,3]). ...
Significant progress has been made in forecasting hazardous atmospheric events such as catastrophic and severe tornadoes (level EF3-EF5). A method for non-stochastic long-term forecasting using the pattern recognition theory and Fourier analysis has recently been developed. A close correlation between the tidal forces of the Earth-Moon-Sun gravitational system and the total number of tornadoes per year was found. However, the physical mechanism of this connection remains closed. In this work, we suggest a novel common physical-mathematical model. This model explains the formation process of a strong tornado, which is divided into two stages. First, gravity forces and hurricane winds in the upper troposphere form a long nonlinear wave in the lower troposphere. Storm winds in the upper troposphere occur when cold air masses penetrate warm areas. These areas are usually associated with synoptic cyclones carrying thunderclouds and rain. Second, the wind in the upper atmosphere and nonlinearity amplifies the resulting gravity nonlinear wave, which propagates at the speed of the initial tidal wave. When a gravity wave reaches a thunderstorm supercell that has already formed inside the atmospheric front, it is captured by the supercell because upward air movements destroy its inversion. As meteorological conditions adapt to weather conditions, the pressure within the thunderstorm cell decreases, and wind speed Significant progress has been made in forecasting hazardous atmospheric events such as catastrophic and severe tornadoes (level EF3-EF5). A method for non-stochastic long-term forecasting using the pattern recognition theory and Fourier analysis has recently been developed. A close correlation between the tidal forces of the Earth-Moon-Sun gravitational system and the total number of tornadoes per year was found. However, the physical mechanism of this connection remains closed. In this work, we suggest a novel, improved physical-mathematical model. This model explains the formation process of a strong tornado, which is divided into two stages. First, gravity forces and hurricane winds in the upper troposphere form a long nonlinear wave in the lower troposphere. Storm winds in the upper troposphere occur when cold air masses penetrate warm areas. These areas are usually associated with synoptic cyclones carrying thunderclouds and rain. Second, the wind in the upper atmosphere and nonlinearity amplifies the resulting gravity nonlinear wave, which propagates at the speed of the initial tidal wave. When a gravity wave reaches a thunderstorm supercell that has already formed inside the atmospheric front, it is captured by the supercell because upward air movements destroy its inversion. As meteorological conditions adapt to weather conditions, the pressure within the thunderstorm cell decreases, and wind speed increases, resulting in a violent tornado. The theoretical results enormously agree with physical observations, validating our model. The two-stage model for the occurrence of powerful tornadoes is one of many possible ones. As an alternative, we also proposed a model for the emergence of a tornado from a thundercloud filled with highly rotating mesoscale vortices. In this case, the theory of mesoscale turbulence is used, which allows for the phenomenon of the red turbulent cascade: the energy transfer from smaller turbulent eddies to the region of large scales. The magnetic and electric field generation equations in tornadoes are considered in detail. Several examples illustrate the presented theory and rationalize some aspects of the physical tornado observations. The authors propose that the constructed physical-mathematical models will enable the utilization of the dangerous and powerful energy of tornadoes for industrial and environmental goals.
... For example, the development of non-hydrostatic pressure gradients can contribute to the generation of large updrafts caused by intense vertical wind shear. According to meteorologists, a supercell thunderstorm is characterized by an extremely strong and persistent rotating updraft [2,16]. The radar echo from precipitation must be at least one-third as deep. ...
In this study, we use the S-band Doppler Weather Radar to analyze the weather of a prolonged classical supercell storm that occurred on April 7, 2018, across the Indian state of Bihar. In the early morning hours of April 7th, 2018, a supercell storm with its origins in a colliding cloud mass produced in the Himalayan foothills invaded the Himalayan foothills from the Northwest of Bihar via East Uttar Pradesh. The echo top increased to over 14 kilometers as it moved through the Bihar districts of Siwan and Gopalganj. As it followed, the storm shifted direction, heading northwest. Maximum radar reflectivity reached up to 61 dBz at 11: 32 IST observation (seen from Doppler Weather Radar, Patna), which may be the highest reflectivity ever recorded at DWR (Doppler Weather Radar) Station, Patna. It stopped being a supercell at 13: 30 IST and convert into a multicellular storm. A strange hook echo could be seen off the Storm's back in the Vertical Integrated Liquid profile. The supercell had two linked outflows, one to the northeast and one to the southeast. The Supercell's inverted "V"-shaped front flank was another characteristic feature. Within a small vertical band along the echo wall, reflectance reached over 60 dB at its highest. There was significant divergence near the peak of the supercell storm, with the speed differential between the updraft and downdraft reaching around 60 m/s. The system lasted for about 7 to 8 hours, damaging hailstorms occurred often along the path. Hail stones larger than 6-7 mm in diameter were spotted (as per the observed report). This particular cell was determined to be a supercell based on its internal structure, reflectivity, duration, and ground-level weather pattern. The incidence, timing, and development of the storms were all accurately predicted by the convective outlook products 2 to 3 hours in advance.
... In the past, extreme weather events have caused almost unimaginable damage. For example, the 1999 Bridge Creek-Newcastle EF5 wedge tornado had the longest continuous tornado path on record, at 116 miles, before it broke up, but it still did unimaginable damage (Burgess et al., 2002). In recent years, the El Reno tornado in 2013 had a record-breaking width of 3.9 miles, and the terrible outbreak seasons in May 2003 and 2020 each produced over 100 tornadoes across the area (Agee et al., 2016; NWS, 2022). ...
... Over the course of two days, May 3-4, 1999, Oklahoma was hit by one of the worst tornado events ever. There were 46 storms across the state during this event, which caused a lot of damage and death (Burgess et al., 2002). Seven of those 46 tornadoes were judged to be strong EF3s, and three were so strong that their winds were over 200 mph, making them EF5s. ...
... Two of the most dangerous tornadoes were an EF5 with a very long path that hit Bridge Creek-Newcastle and killed 36 people and an EF4 that damaged buildings in downtown Oklahoma City. Burgess et al. (2002) say that the Bridge Creek-Newcastle EF5 tornado had the longest unbroken tornado path on the ground, at 116 miles. Along its path, it destroyed whole neighbourhoods and community buildings, leaving little that can be recognised in the rubble. ...
Citizens proactively preparing themselves and working together at the neighbourhood level are often key to a successful disaster reaction. When communities don't have a lot of outside help after a disaster, this article looks at how grassroots organising and adaptive survival techniques can help them stay alive and get back on their feet. Texas tornadoes and Hurricane Katrina are two examples of how citizen-led planning and mutual help can fill in important gaps in response. When official first responders are too busy, Oklahomans help each other out by giving each other emergency supplies, a place to stay, and search and rescue services. People in the community came together during Hurricane Katrina in 2005 to give out supplies and provide housing for people who were stuck for days without help. With decentralised preparation, this book suggests flexible methods that people and communities can use to become more resilient. Communication networks should be set up using all available channels; complete emergency supply kits should be put together and updated on a regular basis; backup power and clean water sources should be made sure of; shelters should be strengthened to withstand high winds and flooding; and coordinated evacuation and neighbourhood watch plans should be made. Citizens can help each other on their own if reaction capabilities are exceeded by setting up localised chains of command, stockpiling supplies, and making it clear who is responsible for sheltering who. In order to better coordinate their efforts and get back on their feet faster after a disaster, communities that establish clear roles and mutual deals are better organised. By applying adaptive strategies, citizens can overcome resource limitations and environmental vulnerabilities through self-sufficiency and mutual aid. Widespread civilian preparation and cooperation builds resilience to withstand catastrophic events when facing delayed or restricted formalized relief efforts.
... Figure 3 shows the appearance of the supercell in its mature stage at different resolutions. Common storm features can be seen, including protruding overshooting tops and a wide-spreading anvil (Doswell & Burgess, 1993). All simulations have a storm of similar dimensions: about 40 km in both x and y directions. ...
We investigate the representation of individual supercells and intriguing tornado‐like vortices in a simplified, locally refined global atmosphere model. The model, featuring grid stretching, can locally enhance the model resolution and reach cloud‐resolving scales with modest computational resources. Given a conditionally unstable sheared environment, the model can simulate supercells realistically, with a near‐ground vortex and funnel cloud at the center of a rotating updraft reminiscent of a tornado. An analysis of the Eulerian vertical vorticity budget suggests that the updraft core of the supercell tilts horizontal vorticity into the tornado‐like vortex, which is then amplified through vertical stretching by the updraft. Results suggest that the simulated vortex is dynamically similar to observed tornadoes, as well as those simulated in modeling studies at much higher horizontal resolution. Lastly, we discuss the prospects for the study of cross‐scale interactions involving supercells.
... Although many of the elements discussed herein apply to all types of tornadoes, we focus on those forming in supercells (Browning 1962;Doswell and Burgess 1993;Rotunno 1993) because they have the largest impact (Brotzge et al. 2013; Anderson-Frey and Brooks 2019). Supercells are "well-organized, monolithic units of vigorous long-lasting convection. ...
Over the last decade, supercell simulations and observations with ever increasing resolution have provided new insights into the vortex-scale processes of tornado formation. This article incorporates these and other recent findings into the existing three-step model by adding an additional fourth stage. The goal is to provide an updated and clear picture of the physical processes occurring during tornadogenesis. Specifically, we emphasize the importance of the low-level wind shear and mesocyclone for tornado potential, the organization and interaction of relatively small-scale pre-tornadic vertical vorticity maxima, and the transition to a tornado-characteristic flow. Based on these insights, guiding research questions are formulated for the decade ahead.
... The presence of a deep and persistent rotating updraft, known as a mesocyclone in supercells (Doswell and Burgess 1993), enables the efficient transport of large amounts of supercooled liquid cloud droplets to the mixed-phase region (from 08 to 2408C). The abundant supply of supercooled water is conducive to the formation of Z DR and K DP columns as well as charge separation between ice crystals and graupel. ...
The dual-polarization radar characteristics of severe storms are commonly used as indicators to estimate the size and intensity of deep convective updrafts. In this study, we track rapid fluctuations in updraft intensity and size by objectively identifying polarimetric fingerprints such as Z DR and K DP columns, which serve as proxies for mixed-phase updraft strength. We quantify the volume of Z DR and K DP columns to evaluate their utility in diagnosing temporal variability in lightning flash characteristics. Specifically, we analyze three severe storms that developed in environments with low-to-moderate instability and strong 0–6-km wind shear in northern Alabama during the 2016–17 VORTEX-Southeast field campaign. In these three cases (a tornadic supercell embedded in stratiform precipitation, a nontornadic supercell, and a supercell embedded within a quasi-linear convective system), we find that the volume of the K DP columns exhibits a stronger correlation with the total flash rate. The higher covariability of the K DP column volume with the total flash rate suggests that the overall electrification and precipitation microphysics were dominated by cold cloud processes. The lower covariability with the Z DR column volume indicates the presence of nonsteady updrafts or a less prominent role of warm rain processes in graupel growth and subsequent electrification. Furthermore, we observe that the majority of cloud-to-ground (CG) lightning strikes a carried negative charge to the ground. In contrast to findings from a tornadic supercell over the Great Plains, lightning flash initiations in the Alabama storms primarily occurred outside the footprint of the Z DR and K DP column objects.
Significance Statement
This study quantifies the correlation between mixed-phase updraft intensity and total lightning flash rate in three severe storms in northern Alabama. In the absence of direct updraft velocity measurements, we use polarimetric signatures, such as Z DR and K DP columns, as proxies for updraft strength. Our analysis of polarimetric radar and lightning mapping array data reveals that the lightning flash rate is more highly correlated with the K DP column volume than with the Z DR column volume in all three storms examined. This contrasts with previous findings in storms over the central Great Plains, where the Z DR column volume showed higher covariability with flash rate. Interestingly, lightning initiation in the Alabama storms mainly occurred outside the Z DR and K DP column areas, contrary to previous findings.
... This system was primarily nocturnal in nature and tended to form over or in close proximity to land. This MCC has a cloud shield with a continuous low IR temperature of less than -33 C over an area of more than 100000 km 2 and a cloud shield with a continuous low IR temperature of less than -54 C over an area of more than 50000 km 2 [ Fig. 15 When the observational resolution is high enough, supercells often exhibit multicellular traits, thus, we do not consider a supercell to be a single-cell event (Doswell and Burgess 1993). In the case of flash floods, supercells' proclivity for heavy updrafts is critical. ...
The present study analyses and describes the evolution of the Mesoscale Convective Complex (MCC) and its atmospheric conditions during Extreme rainfall event in Hyderabad, on 13 th October 2020. This extreme weather event was a mesoscale event embedded in a synoptic-scale system. During the second week of October 2020, a depression formed over the west-central Bay of Bengal (BoB) and travelled north-westwards through peninsular India, causing heavy rains in Andhra Pradesh and Telangana states of India on October 13-14. On October 13, many parts of Hyderabad and Cyberabad received more than 300 mm of rain within 24 hrs. Satellite imagery suggests that this mesoscale system constituted a unique set of structured convection those reported in MCC. This MCC has a cloud shield with a continuous low IR temperature of less than-33 C over an area of more than 100000 km 2 and a cloud shield with a continuous low IR temperature of less than-54 C over an area of more than 50000 km 2 over Hyderabad with a life cycle of about 9 hours. This MCC featured multi cellular characteristics, showing that there was significant low-level moisture in its environment, as well as a mix of vigorous updrafts, implying significant rainfall rates over Hyderabad. The synoptic features suggest that with high precipitable water, the long axis of low-level moisture convergence at 0850 hPa and large horizontal vorticity at 0925 hPa were oriented parallel to the system's mean wind flow. In this case, a clusters of thunderstorms arose in the area of moisture convergence which prolonged the duration of extremely heavy rainfall. The high rain rate, relatively sluggish storm motion, and prolonged back-building over the same locations for several hours are likely to blame for the heavy rainfall accumulations that were observed. The hydrological conditions compounded the effects of the torrential rain, resulting in a natural hazard.
... Furthermore, the classification of strong mesocyclone contained the largest number of hailstorms associated with LHEs (8 of 19). According to the general definition of supercell suggested by Burgess and Lemon (1990) and Doswell and Burgess (1993), most of the hailstorms associated with LHEs in present study can actually be classified as supercells. The close link between mesocyclones and LHEs has also been suggested by previous studies (Miller et al. 1988;Witt et al. 1998;Blair et al. 2011;Wapler 2017). ...
Using hail records at national meteorological stations for 2014–18, ERA-Interim reanalysis data, and Doppler weather radar data, the spatiotemporal distribution of hail events (HEs) in the Beijing–Tianjin–Hebei region is revealed, and the environmental conditions and hailstorm structures corresponding to large hail (diameter ≥ 20 mm) events (LHEs) and small hail (2 ≤ diameter < 20 mm) events (SHEs) are compared. It is found that, although HEs may be more frequent in mountainous areas, most LHEs occur in the plains and near the foot of the mountains. The HE frequency peaks in June, and the average hailstone size is larger during May and June. According to daytime records, the HEs predominantly occur in the afternoon and evening, whereas LHE tends to be more in the evening. Comparison of environmental parameters suggests that, relative to SHEs, LHEs tend to correspond to higher 2-m temperature, a wetter lower layer, a larger difference in relative humidity between 925 and 500 hPa, greater unstable energy, and stronger wind shear. Hailstorms associated with LHEs tend to feature greater mesoscale rotation velocity than those associated with SHEs. Hailstorms usually show rapid increase (RI) in vertically integrated liquid (VIL) before hailstones are observed. A significant difference between the hailstorms associated with LHEs and SHEs is that the former has an obviously longer time interval between the end of VIL RI and the occurrence of hailfall, indicating that the large hail size benefits from the constant supply of liquid water and the hail can be lifted by updrafts for a long time.
Significance Statement
Whereas previous studies have predominantly focused on large hail (diameter ≥ 20 mm) events (LHEs) and their yielding conditions, this study was devoted to examining the difference between the LHEs and small hail (2 ≤ diameter < 20 mm) events in their associated atmospheric environments and storm structures. The interesting new insight is that the hailstorms yielding LHEs tend to feature a significantly longer time interval after the rapid increase of vertically integrated liquid and before hailfall. This study can provide a reference for the early warning of the scale of hail, which is one of the difficulties of weather services.
