Proposed Large-Scale Modelling of the Transient Features of a Downburst Outflow
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Fatalities Associated with the Severe Weather Conditions in the Czech Republic, 2000–2019
Nat. Hazards Earth Syst. Sci., 21, 1355–1382, 2021 https://doi.org/10.5194/nhess-21-1355-2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Fatalities associated with the severe weather conditions in the Czech Republic, 2000–2019 Rudolf Brázdil1,2, Katerinaˇ Chromá2, Lukáš Dolák1,2, Jan Rehoˇ rˇ1,2, Ladislava Rezníˇ ckovᡠ1,2, Pavel Zahradnícekˇ 2,3, and Petr Dobrovolný1,2 1Institute of Geography, Masaryk University, Brno, Czech Republic 2Global Change Research Institute, Czech Academy of Sciences, Brno, Czech Republic 3Czech Hydrometeorological Institute, Brno, Czech Republic Correspondence: Rudolf Brázdil ([email protected]) Received: 12 January 2021 – Discussion started: 21 January 2021 Revised: 25 March 2021 – Accepted: 26 March 2021 – Published: 4 May 2021 Abstract. This paper presents an analysis of fatalities at- with fatal accidents as well as a decrease in their percent- tributable to weather conditions in the Czech Republic dur- age in annual numbers of fatalities. The discussion of results ing the 2000–2019 period. The database of fatalities de- includes the problems of data uncertainty, comparison of dif- ployed contains information extracted from Právo, a lead- ferent data sources, and the broader context. ing daily newspaper, and Novinky.cz, its internet equivalent, supplemented by a number of other documentary sources. The analysis is performed for floods, windstorms, convective storms, rain, snow, glaze ice, frost, heat, and fog. For each 1 Introduction of them, the associated fatalities are investigated in terms of annual frequencies, trends, annual variation, spatial distribu- Natural disasters are accompanied not only by extensive ma- tion, cause, type, place, and time as well as the sex, age, and terial damage but also by great loss of human life, facts easily behaviour of casualties. -
The Generation of a Mesoscale Convective System from Mountain Convection
JUNE 1999 TUCKER AND CROOK 1259 The Generation of a Mesoscale Convective System from Mountain Convection DONNA F. T UCKER Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas N. ANDREW CROOK National Center for Atmospheric Research Boulder, Colorado (Manuscript received 18 November 1997, in ®nal form 13 July 1998) ABSTRACT A mesoscale convective system (MCS) that formed just to the east of Denver is investigated with a nonhy- drostatic numerical model to determine which processes were important in its initiation. The MCS developed from out¯ow from previous convective activity in the Rocky Mountains to the west. Model results indicate that this out¯ow was necessary for the development of the MCS even though a convergence line was already present in the area where the MCS developed. A simulation with a 3-km grid spacing more fully resolves the convective activity in the mountains but the development of the MCS can be simulated with a 6.67-km grid. Cloud effects on solar radiation and ice sedimentation both in¯uence the strength of the out¯ow from the mountain convection but only the ice sedimentation makes a signi®cant impact on the development of the MCS after its initiation. The frequent convective activity in the Rocky Mountains during the warm season provides out¯ow that would make MCS generation favorable in this region. Thus, there is a close connection between mountain convective activity and MCS generation. The implications of such a connection are discussed and possible directions of future research are indicated. 1. Introduction scale or mesoscale. Forced lifting always occurs on the windward side of mountains; however, the mechanisms Mesoscale convective systems (MCSs) commonly de- that promote lifting on the downwind side of mountains, velop in the central United States during the warm sea- where a large proportion of MCSs initiate, are not as son, accounting for 30%±70% of the summer precipi- obvious. -
The Impact of Outflow Environment on Tropical Cyclone Intensification And
VOLUME 68 JOURNAL OF THE ATMOSPHERIC SCIENCES FEBRUARY 2011 The Impact of Outflow Environment on Tropical Cyclone Intensification and Structure ERIC D. RAPPIN Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida MICHAEL C. MORGAN AND GREGORY J. TRIPOLI University of Wisconsin—Madison, Madison, Wisconsin (Manuscript received 3 October 2008, in final form 5 June 2009) ABSTRACT In this study, the impacts of regions of weak inertial stability on tropical cyclone intensification and peak strength are examined. It is demonstrated that weak inertial stability in the outflow layer minimizes an energy sink of the tropical cyclone secondary circulation and leads to more rapid intensification to the maximum potential intensity. Using a full-physics, three-dimensional numerical weather prediction model, a symmetric distribution of environmental inertial stability is generated using a variable Coriolis parameter. It is found that the lower the value of the Coriolis parameter, the more rapid the strengthening. The lower-latitude simulation is shown to have a significantly stronger secondary circulation with intense divergent outflow against a com- paratively weak environmental resistance. However, the impacts of differences in the gradient wind balance between the different latitudes on the core structure cannot be neglected. A second study is then conducted using an asymmetric inertial stability distribution generated by the presence of a jet stream to the north of the tropical cyclone. The initial intensification is similar, or even perhaps slower, in the presence of the jet as a result of increased vertical wind shear. As the system evolves, convective outflow from the tropical cyclone modifies the jet resulting in weaker shear and more rapid intensification of the tropical cyclone–jet couplet. -
An Observational Analysis Quantifying the Distance of Supercell-Boundary Interactions in the Great Plains
Magee, K. M., and C. E. Davenport, 2020: An observational analysis quantifying the distance of supercell-boundary interactions in the Great Plains. J. Operational Meteor., 8 (2), 15-38, doi: https://doi.org/10.15191/nwajom.2020.0802 An Observational Analysis Quantifying the Distance of Supercell-Boundary Interactions in the Great Plains KATHLEEN M. MAGEE National Weather Service Huntsville, Huntsville, AL CASEY E. DAVENPORT University of North Carolina at Charlotte, Charlotte, NC (Manuscript received 11 June 2019; review completed 7 October 2019) ABSTRACT Several case studies and numerical simulations have hypothesized that baroclinic boundaries provide enhanced horizontal and vertical vorticity, wind shear, helicity, and moisture that induce stronger updrafts, higher reflectivity, and stronger low-level rotation in supercells. However, the distance at which a surface boundary will provide such enhancement is less well-defined. Previous studies have identified enhancement at distances ranging from 10 km to 200 km, and only focused on tornado production and intensity, rather than all forms of severe weather. To better aid short-term forecasts, the observed distances at which supercells produce severe weather in proximity to a boundary needs to be assessed. In this study, the distance between a large number of observed supercells and nearby surface boundaries (including warm fronts, stationary fronts, and outflow boundaries) is measured throughout the lifetime of each storm; the distance at which associated reports of large hail and tornadoes occur is also collected. Statistical analyses assess the sensitivity of report distributions to report type, boundary type, boundary strength, angle of interaction, and direction of storm motion relative to the boundary. -
Downbursts: As Dangerous As Tornadoes? Winds Can Be Experienced Along the Leading Edge of This “Spreading Out” Air
DDoowwnnbbuurrssttss:: AAss DDaannggeerroouuss aass TToorrnnaaddooeess?? National Weather Service Greenville-Spartanburg, SC What is a Downburst? “It had to be a tornado!” This is a “updraft.” common statement made by citizens of the Carolinas and On a typical day in the warm season, North Georgia who experience once a cloud grows to 20,000 to damaging winds associated with 30,000 feet, it will begin to produce severe thunderstorms, especially heavy rain and lightning. The falling if those winds cause damage to rain causes a “downdraft,” or sinking their homes. However, the column of air to form. A thunderstorm combination of atmospheric may eventually grow to a height of ingredients that are necessary for 50,000 feet or more before it stops tornadoes occurs only rarely developing. Generally speaking, the across our area. In fact the 46 Fig. 1. Tracks of tornadoes across the “taller” the storm, the more likely it is Carolinas and Georgia from 1995 through counties that represent the to produce a strong downdraft. Once 2011. Compare this with the downburst Greenville-Spartanburg Weather reports during this time (Figure 3). the air within the downdraft reaches Forecast Offices’s County Warning the surface, it spreads out parallel to Area only experience a total of 12 the ground. Very strong to damaging to 15 tornadoes during an average year. However, thunderstorms and even severe thunderstorms are a relatively common occurrence across our area, especially from late spring through mid-summer. This is because a warm and humid (i.e., unstable) atmosphere is required for thunderstorm development. If some atmospheric process forces the unstable air Fig. -
Outflow from a Nocturnal Thunderstorm
State Water Survey Division METEOROLOGY SECTION AT THE UNIVERSITY OF ILLINOIS SWS Contract Report 242 OUTFLOW FROM A NOCTURNAL THUNDERSTORM Robert W. Scott Meteorology Section Illinois State Water Survey Technical Report 3 NSF Grant ATM 78-08865 Low Level Convergence and the Prediction of Convective Precipitation November 1980 Champaign IL 61820 The project "Low-level Convergence and the Prediction of Convective Precipitation" is a coordinated research effort by the State Water Survey Division of the Illinois Institute of Natural Resources, the Off ice of Weather Modification Research in the National Oceanic and Atmospheric Adminis tration, and the Department of Environmental Sciences of the University of Virginia. Support of this research has been provided to the State Water Survey by the Atmospheric Research Section, National Science Founda tion, through grant ATM-78-08865. This award includes funds from the Army Research Office and the Air Force Office of Scientific Research of the Department of Defense. OUTFLOW FROM A NOCTURNAL THUNDERSTORM Robert W. Scott Illinois State Water Survey TABLE OF CONTENTS Page LIST OF FIGURES iii ABSTRACT .. v ACKNOWLEDGMENTS vii INTRODUCTION 1 STORM CONDITIONS 2 METEOROLOGICAL FIELDS IN THE NETWORK 8 DISCUSSION 19 REFERENCES 26 -iii- LIST OF FIGURES Figure Page 1 Synoptic analyses on 8-9 August 1979. a. Surface chart at 1900 CDT on 8 August 1979. b. Surface chart at 0700 CDT on 9 August 1979 3 c. 850-mb chart at 1900 CDT on 8 August 1979. d. 850-mb chart at 0700 CDT on 9 August 1979 4 e. 700-mb chart at 1900 CDT on 8 August 1979. -
ESSENTIALS of METEOROLOGY (7Th Ed.) GLOSSARY
ESSENTIALS OF METEOROLOGY (7th ed.) GLOSSARY Chapter 1 Aerosols Tiny suspended solid particles (dust, smoke, etc.) or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. Air density The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm3 or kg/m3. Also See Density. Air pressure The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of (atmospheric mercury (Hg) or in hectopascals (hPa). pressure) Atmosphere The envelope of gases that surround a planet and are held to it by the planet's gravitational attraction. The earth's atmosphere is mainly nitrogen and oxygen. Carbon dioxide (CO2) A colorless, odorless gas whose concentration is about 0.039 percent (390 ppm) in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in the earth's atmospheric greenhouse effect. Solid CO2 is called dry ice. Climate The accumulation of daily and seasonal weather events over a long period of time. Front The transition zone between two distinct air masses. Hurricane A tropical cyclone having winds in excess of 64 knots (74 mi/hr). Ionosphere An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist. Lapse rate The rate at which an atmospheric variable (usually temperature) decreases with height. (See Environmental lapse rate.) Mesosphere The atmospheric layer between the stratosphere and the thermosphere. -
Radar Artifacts and Associated Signatures, Along with Impacts of Terrain on Data Quality
Radar Artifacts and Associated Signatures, Along with Impacts of Terrain on Data Quality 1.) Introduction: The WSR-88D (Weather Surveillance Radar designed and built in the 80s) is the most useful tool used by National Weather Service (NWS) Meteorologists to detect precipitation, calculate its motion, estimate its type (rain, snow, hail, etc) and forecast its position. Radar stands for “Radio, Detection, and Ranging”, was developed in the 1940’s and used during World War II, has gone through numerous enhancements and technological upgrades to help forecasters investigate storms with greater detail and precision. However, as our ability to detect areas of precipitation, including rotation within thunderstorms has vastly improved over the years, so has the radar’s ability to detect other significant meteorological and non meteorological artifacts. In this article we will identify these signatures, explain why and how they occur and provide examples from KTYX and KCXX of both meteorological and non meteorological data which WSR-88D detects. KTYX radar is located on the Tug Hill Plateau near Watertown, NY while, KCXX is located in Colchester, VT with both operated by the NWS in Burlington. Radar signatures to be shown include: bright banding, tornadic hook echo, low level lake boundary, hail spikes, sunset spikes, migrating birds, Route 7 traffic, wind farms, and beam blockage caused by terrain and the associated poor data sampling that occurs. 2.) How Radar Works: The WSR-88D operates by sending out directional pulses at several different elevation angles, which are microseconds long, and when the pulse intersects water droplets or other artifacts, a return signal is sent back to the radar. -
Mesoscale Convective Complexes: an Overview by Harold Reynolds a Report Submitted in Conformity with the Requirements for the De
Mesoscale Convective Complexes: An Overview By Harold Reynolds A report submitted in conformity with the requirements for the degree of Master of Science in the University of Toronto © Harold Reynolds 1990 Table of Contents 1. What is a Mesoscale Convective Complex?........................................................................................ 3 2. Why Study Mesoscale Convective Complexes?..................................................................................3 3. The Internal Structure and Life Cycle of an MCC...............................................................................4 3.1 Introduction.................................................................................................................................... 4 3.2 Genesis........................................................................................................................................... 5 3.3 Growth............................................................................................................................................6 3.4 Maturity and Decay........................................................................................................................ 7 3.5 Heat and Moisture Budgets............................................................................................................ 8 4. Precipitation......................................................................................................................................... 8 5. Mesoscale Warm-Core Vortices....................................................................................................... -
Tropical Cyclone Tauktae
Tropical Cyclone Tauktae - Estimated Impacts Warning 7, 15 May 2021 2100 UTC PDC-1I-7A JTWC Summary: TROPICAL CYCLONE 01A (TAUKTAE), LOCATED APPROXIMATELY 263 NM SOUTH OF MUMBAI, INDIA, HAS TRACKED NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS.ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM CONTINUED TO CONSOLIDATE AND HAS BECOME MORE SYMMETRICAL WITH A DEEPENING CENTRAL DENSE OVERCAST AND AN EVOLVING EYE FEATURE.THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE LOW LEVEL CIRCULATION FEATURE IN THE 151703Z AMSU-B 89GHZ PASS AND COMPOSITE WEATHER RADAR LOOP FROM GOA, INDIA.THE INITIAL INTENSITY 65 KNOTS IS BASED ON THE PGTW DVORAK ESTIMATE OF T4.0/65KTS AND ADT OF T3.9/63KTS.THE UPPER-LEVEL ANALYSIS INDICATES FAVORABLE ENVIRONMENTAL CONDITIONS WITH ROBUST POLEWARD OUTFLOW, LOW VERTICAL WIND SHEAR (10-15KTS), AND WARM (31C) SEA SURFACE TEMPERATURE.TC 01A IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST AND WILL CONTINUE ON ITS CURRENT TRACK THROUGH TAU 36.AFTERWARD, IT WILL TRACK MORE NORTHWARD AND ROUND THE RIDGE AXIS BEFORE MAKING LANDFALL NEAR VERAVAL, INDIA SHORTLY AFTER TAU 48.THE POSSIBILITY OF RAPID INTENSIFICATION (RI) REMAINS HIGH DURING THE NEXT 24 TO 36 HOURS AS THE ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE, REACHING A PEAK INTENSITY OF 105 KNOTS BY TAU 36.AFTERWARD, THE SYSTEM WILL BEGIN TO WEAKEN WITH LAND INTERACTION.AFTER LANDFALL, THE CYCLONE WILL RAPIDLY ERODE AS IT TRACKS ACROSS THE RUGGED TERRAIN, LEADING TO DISSIPATION BY TAU 120, POSSIBLY -
Glossary of Severe Weather Terms
Glossary of Severe Weather Terms -A- Anvil The flat, spreading top of a cloud, often shaped like an anvil. Thunderstorm anvils may spread hundreds of miles downwind from the thunderstorm itself, and sometimes may spread upwind. Anvil Dome A large overshooting top or penetrating top. -B- Back-building Thunderstorm A thunderstorm in which new development takes place on the upwind side (usually the west or southwest side), such that the storm seems to remain stationary or propagate in a backward direction. Back-sheared Anvil [Slang], a thunderstorm anvil which spreads upwind, against the flow aloft. A back-sheared anvil often implies a very strong updraft and a high severe weather potential. Beaver ('s) Tail [Slang], a particular type of inflow band with a relatively broad, flat appearance suggestive of a beaver's tail. It is attached to a supercell's general updraft and is oriented roughly parallel to the pseudo-warm front, i.e., usually east to west or southeast to northwest. As with any inflow band, cloud elements move toward the updraft, i.e., toward the west or northwest. Its size and shape change as the strength of the inflow changes. Spotters should note the distinction between a beaver tail and a tail cloud. A "true" tail cloud typically is attached to the wall cloud and has a cloud base at about the same level as the wall cloud itself. A beaver tail, on the other hand, is not attached to the wall cloud and has a cloud base at about the same height as the updraft base (which by definition is higher than the wall cloud). -
Tropical Cyclones: Formation, Maintenance, and Intensification
ESCI 344 – Tropical Meteorology Lesson 11 – Tropical Cyclones: Formation, Maintenance, and Intensification References: A Global View of Tropical Cyclones, Elsberry (ed.) Global Perspectives on Tropical Cylones: From Science to Mitigation, Chan and Kepert (ed.) The Hurricane, Pielke Tropical Cyclones: Their evolution, structure, and effects, Anthes Forecasters’ Guide to Tropical Meteorology, Atkinsson Forecasters Guide to Tropical Meteorology (updated), Ramage ‘Tropical cyclogenesis in a tropical wave critical layer: easterly waves’, Dunkerton, Montgomery, and Wang Atmos. Chem. and Phys. 2009. Global Guide to Tropical Cyclone Forecasting, Holland (ed.), online at http://www.bom.gov.au/bmrc/pubs/tcguide/globa_guide_intro.htm Reading: An Introduction to the Meteorology and Climate of the Tropics, Chapter 9 A Global View of Tropical Cyclones, Chapter 3, Frank Hurricane, Chapter 2, Pielke GENERAL CONSIDERATIONS Tropical convection acts as a heat engine, taking warm moist air from the surface and converting the latent heat into kinetic energy in the updraft, which is then exhausted into the upper troposphere. If the circulation can overcome the dissipating effects of friction it can become self-sustaining. In order for a convective cloud cluster to result in pressure falls at the surface, there must be a net removal of mass from the air column (net vertically integrated divergence). Since there is compensating subsidence nearby, outside of a typical convective cloud, there really isn’t much integrated mass divergence. Pressure really won’t fall unless there is a mechanism to remove the mass that is exhausted well away from the convection. Compensating subsidence near the convection also serves to decrease the buoyancy within the clouds, because the subsiding air will also warm.