DOCSLIB.ORG

The Impact of Dry Air on the Location of Tornado Outbreaks Associated with Landfalling Tropical Cyclones in the Atlantic Basin

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Impact of Dry Air on the Location of Tornado Outbreaks Associated with Landfalling Tropical Cyclones in the Atlantic Basin The Impact of Dry Air on the Location of Tornado Outbreaks Associated with Landfalling Tropical Cyclones in the Atlantic Basin THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Christian David Feliciano-Camacho Graduate Program in Atmospheric Sciences The Ohio State University 2016 Master's Examination Committee: Jay S. Hobgood, “Advisor” Jialin Lin Copyrighted by Christian David Feliciano-Camacho 2016 Abstract Tropical cyclones that form in the Atlantic Basin are responsible for causing major disruptions across a wide range of industries from government policy to transportation and tourism. With the continuous growth of coastal cities continuing, there has been an increasing demand for the scientific community to accurately predict the tracks and intensities of tropical cyclones in order to mitigate disruptions and damages. Although the scientific community has made tremendous advances in forecasting the tracks of tropical cyclones, predicting intensity has proven to be incredibly challenging. What has proved to be equally as difficult is predicting tropical cyclones that are capable of producing tornado outbreaks. Tornadoes that form as a result of tropical cyclones represent a small percentage of total tornado reports and they are often weaker compared to their supercell counterparts from mid latitude systems. Even though these tornadoes are not as common or as severe as supercell tornadoes that occur over the Great Plains, they are a serious threat to life and property. Recently it has been shown that dry air may be used as an indicator to pinpoint the location of tornado outbreaks which could give forecasters more lead time in alerting the public. Dry air can increase convective available potential energy (CAPE) which can lead to stronger updrafts, or it can lead to skies remaining clear so that solar radiation can heat the surface, eroding away any convective inhibition. All tropical cyclones that have made landfall between 2000 and 2014, regardless of their intensity, that produced at least six tornadoes within a 24 hour ii period before or after landfall were analyzed to determine any distinguishable patterns between dry air intrusions and the location of the tornado outbreaks. Dry air intrusions were easily visible by locating steep gradients in relative humidity. Images of relative humidity were created in Matlab using the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis data for 700, 500, 400, and 300 hPa. Atmospheric soundings were used to analyze and verify if the observed conditions match what is being displayed by the reanalysis data. Finally, simple calculations were performed as well as an analysis on the location of the relative humidity gradients in order to separate each tropical cyclone into various groupings and to discover any noteworthy patterns or trends. iii Vita June 2010 .......................................................Framingham High School 2014................................................................B.S. Atmospheric Science, State University of New York at Albany 2014 to present ..............................................Graduate Teaching Associate, Department of Geography, The Ohio State University Fields of Study Major Field: Atmospheric Sciences iv Table of Contents Abstract ............................................................................................................................... ii Vita .................................................................................................................................... iiv List of Tables ..................................................................................................................... vi List of Figures ................................................................................................................... vii Chapter 1: Introduction ....................................................................................................... 1 Chapter 2: Methodology ................................................................................................... 10 Chapter 3: Results ............................................................................................................. 13 Chapter 4: Tornado Statistics .......................................................................................... 246 Chapter 5: Results & Discussion .................................................................................... 257 References ....................................................................................................................... 266 v List of Tables Table 1. Comparison of average LCL height and dewpoint depression (8C) at various levels in storms with midlevel dry intrusions that produced outbreaks (qualifying), storms without midlevel dry intrusions that produced outbreaks (nonqualifying), and storms with midlevel dry intrusions that failed to produce outbreaks (null). ......................................... 9 Table 2. Tropical cyclones associated with each group based on total number of tornadoes located under a RH gradient. .......................................................................... 255 Table 3. Tornado statistics calculated for each grouping ............................................... 256 Table 4. Examined tropical cyclones with an “X” denoting which level an RH gradient was found over at least one tornado outbreak ………………………………………….264 Table 5. Characterized location of the RH gradients associated with each tropical cyclone………………………………………………………………………………….265 vi List of Figures Figure 1. Position and track of Tropical Storm Alberto 10-14 June, 2006 created by NOAA and NHC. Image taken from National Hurricane Center tropical cyclone report. ................................................................................................................................ 18 Figure 2. Relative humidity for 300, 400, 500, and 700 hPa for 1200 UTC on 12 June. Images created using the European Centre for Medium-Range Weather Forecasts ERA- Interim reanalysis data within Matlab. Warmer colors indicate dry air while cooler colors indicate moist air. Black star indicates the location of the tropical cyclone at the current time. Dots represent the location of the various tornadoes that spawned at that time. ..... 19 Figure 3. Relative humidity for 300, 400, 500, and 700 hPa for 0600 UTC on 13 June. Images created using the European Centre for Medium-Range Weather Forecasts ERA- Interim reanalysis data within Matlab. Warmer colors indicate dry air while cooler colors indicate moist air. Black star indicates the location of the tropical cyclone at the current time. Dots represent the location of the various tornadoes that spawned at that time. ..... 20 Figure 4. Relative humidity for 300, 400, 500, and 700 hPa for 1200 UTC on 13 June. Images created using the European Centre for Medium-Range Weather Forecasts ERA- Interim reanalysis data within Matlab. Warmer colors indicate dry air while cooler colors indicate moist air. Black star indicates the location of the tropical cyclone at the current time. Dots represent the location of the various tornadoes that spawned at that time. ..... 21 vii Figure 5. Atmospheric profile sounding for Jacksonville, Florida taken at 0000 UTC on June 13. Sounding taken from the University of Wyoming Department of Atmospheric Science sounding page ...................................................................................................... 22 Figure 6. Atmospheric profile sounding for Jacksonville, Florida taken at 1200 UTC on June 13. Sounding was taken from the University of Wyoming Department of Atmospheric Science sounding page. ............................................................................... 23 Figure 7. Relative humidity for 300, 400, 500, and 700 hPa for 1800 UTC on 13 June. Images created using the European Centre for Medium-Range Weather Forecasts ERA- Interim reanalysis data within Matlab. Warmer colors indicate dry air while cooler colors indicate moist air. Black star indicates the location of the tropical cyclone at the current time. Dots represent the location of the various tornadoes that spawned at that time ...... 24 Figure 8. Atmospheric profile sounding for Charleston, South Carolina taken at 1200 UTC on June 13. Sounding was taken from the University of Wyoming Department of Atmospheric Science sounding page ................................................................................ 25 Figure 9. Best track positions for Tropical Storm Allison, 5-17 June 2001. Image taken from NCH tropical cyclone report. ................................................................................... 29 Figure 10. Relative humidity for 300, 400, 500, and 700 hPa for 0600 UTC on 11 June. Images created using the European Centre for Medium-Range Weather Forecasts ERA- Interim reanalysis data within Matlab. Warmer colors indicate dry air while cooler colors indicate moist air. Black star indicates the location of the tropical cyclone at the current time. Dots represent the location of the various tornadoes that spawned at that time. ..... 30 viii Figure 11. Relative humidity for 300, 400, 500, and 700 hPa for 1200 UTC on 11 June. Images created using the European Centre for Medium-Range Weather Forecasts ERA- Interim reanalysis data within Matlab. Warmer colors indicate dry air while cooler colors indicate moist air. Black star indicates the location
Load more

Recommended publications
  • Town of East Haven Hazard Mitigation Plan Update 2012
    TOWN OF EAST HAVEN HAZARD MITIGATION PLAN UPDATE 2012 ADOPTED MAY 1, 2012 MMI #2731-02-1 Prepared for: TOWN OF EAST HAVEN Town Hall 200 Main Street East Haven, Connecticut 06512 (203)468–3840 http://www.townofeasthavenct.org/ Prepared by: MILONE & MACBROOM, INC. 99 Realty Drive Cheshire, Connecticut 06410 (203) 271-1773 www.miloneandmacbroom.com TABLE OF CONTENTS Section Page CONTACT INFORMATION ....................................................................................................ES-1 EXECUTIVE SUMMARY .......................................................................................................ES-2 1.0 INTRODUCTION 1.1 Background and Purpose ................................................................................................. 1-1 1.2 Hazard Mitigation Goals .................................................................................................. 1-4 1.3 Identification of Hazards and Document Overview ........................................................ 1-5 1.4 Discussion of STAPLEE Ranking Method.................................................................... 1-10 1.5 Discussion of Benefit-Cost Ratio................................................................................... 1-12 1.6 Documentation of the Planning Process ........................................................................ 1-12 1.7 Coordination with Neighboring Communities ............................................................... 1-12 2.0 COMMUNITY PROFILE 2.1 Physical Setting ...............................................................................................................
    [Show full text]
  • 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.
    [Show full text]
  • Texas Hurricane History
    Texas Hurricane History David Roth National Weather Service Camp Springs, MD Table of Contents Preface 3 Climatology of Texas Tropical Cyclones 4 List of Texas Hurricanes 8 Tropical Cyclone Records in Texas 11 Hurricanes of the Sixteenth and Seventeenth Centuries 12 Hurricanes of the Eighteenth and Early Nineteenth Centuries 13 Hurricanes of the Late Nineteenth Century 16 The First Indianola Hurricane - 1875 21 Last Indianola Hurricane (1886)- The Storm That Doomed Texas’ Major Port 24 The Great Galveston Hurricane (1900) 29 Hurricanes of the Early Twentieth Century 31 Corpus Christi’s Devastating Hurricane (1919) 38 San Antonio’s Great Flood – 1921 39 Hurricanes of the Late Twentieth Century 48 Hurricanes of the Early Twenty-First Century 68 Acknowledgments 74 Bibliography 75 Preface Every year, about one hundred tropical disturbances roam the open Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. About fifteen of these become tropical depressions, areas of low pressure with closed wind patterns. Of the fifteen, ten become tropical storms, and six become hurricanes. Every five years, one of the hurricanes will become reach category five status, normally in the western Atlantic or western Caribbean. About every fifty years, one of these extremely intense hurricanes will strike the United States, with disastrous consequences. Texas has seen its share of hurricane activity over the many years it has been inhabited. Nearly five hundred years ago, unlucky Spanish explorers learned firsthand what storms along the coast of the Lone Star State were capable of. Despite these setbacks, Spaniards set down roots across Mexico and Texas and started colonies. Galleons filled with gold and other treasures sank to the bottom of the Gulf, off such locations as Padre and Galveston Islands.
    [Show full text]
  • Tropical Cyclone Report for Hurricane Ivan
    Tropical Cyclone Report Hurricane Ivan 2-24 September 2004 Stacy R. Stewart National Hurricane Center 16 December 2004 Updated 27 May 2005 to revise damage estimate Updated 11 August 2011 to revise damage estimate Ivan was a classical, long-lived Cape Verde hurricane that reached Category 5 strength three times on the Saffir-Simpson Hurricane Scale (SSHS). It was also the strongest hurricane on record that far south east of the Lesser Antilles. Ivan caused considerable damage and loss of life as it passed through the Caribbean Sea. a. Synoptic History Ivan developed from a large tropical wave that moved off the west coast of Africa on 31 August. Although the wave was accompanied by a surface pressure system and an impressive upper-level outflow pattern, associated convection was limited and not well organized. However, by early on 1 September, convective banding began to develop around the low-level center and Dvorak satellite classifications were initiated later that day. Favorable upper-level outflow and low shear environment was conducive for the formation of vigorous deep convection to develop and persist near the center, and it is estimated that a tropical depression formed around 1800 UTC 2 September. Figure 1 depicts the “best track” of the tropical cyclone’s path. The wind and pressure histories are shown in Figs. 2a and 3a, respectively. Table 1 is a listing of the best track positions and intensities. Despite a relatively low latitude (9.7o N), development continued and it is estimated that the cyclone became Tropical Storm Ivan just 12 h later at 0600 UTC 3 September.
    [Show full text]
  • Geography and Atmospheric Science 1
    Geography and Atmospheric Science 1 Undergraduate Research Center is another great resource. The center Geography and aids undergraduates interested in doing research, offers funding opportunities, and provides step-by-step workshops which provide Atmospheric Science students the skills necessary to explore, investigate, and excel. Atmospheric Science labs include a Meteorology and Climate Hub Geography as an academic discipline studies the spatial dimensions of, (MACH) with state-of-the-art AWIPS II software used by the National and links between, culture, society, and environmental processes. The Weather Service and computer lab and collaborative space dedicated study of Atmospheric Science involves weather and climate and how to students doing research. Students also get hands-on experience, those affect human activity and life on earth. At the University of Kansas, from forecasting and providing reports to university radio (KJHK 90.7 our department's programs work to understand human activity and the FM) and television (KUJH-TV) to research project opportunities through physical world. our department and the University of Kansas Undergraduate Research Center. Why study geography? . Because people, places, and environments interact and evolve in a changing world. From conservation to soil science to the power of Undergraduate Programs geographic information science data and more, the study of geography at the University of Kansas prepares future leaders. The study of geography Geography encompasses landscape and physical features of the planet and human activity, the environment and resources, migration, and more. Our Geography integrates information from a variety of sources to study program (http://geog.ku.edu/degrees/) has a unique cross-disciplinary the nature of culture areas, the emergence of physical and human nature with pathway options (http://geog.ku.edu/geography-pathways/) landscapes, and problems of interaction between people and the and diverse faculty (http://geog.ku.edu/faculty/) who are passionate about environment.
    [Show full text]
  • Hurricane Ike: Do We Need to Change Our Thinking?
    AIRCURRENTS HURRICANE IKE: DO WE NEED TO CHANGE OUR THINKING? EDITor’s noTE: Of the three landfalling U.S. hurricanes in 2008, Hurricane Ike was by far the costliest. Perhaps because it was the largest loss in the last three seasons, it seemed to have captured the imagination of many in the industry, with estimates of as much as $20 billion or more being bandied about in the storm’s early aftermath. In this article, AIR’s Dr. Peter Dailey 12.2008 takes a hard look at the reality of Hurricane Ike. By Dr. Peter S. Dailey, Director of Atmospheric Science INTRODUCTION neither catastrophe modelers—nor the industry—should Hurricane Ike made landfall at Galveston, Texas in the early have been taken by surprise by Ike. While the storm morning hours of September 13, 2008. It was the third displayed some interesting characteristics, and managed and final hurricane to make landfall in the U.S. this year, to cause damage well inland (long after it had been preceded by Hurricane Dolly in late July and Gustav just two downgraded to a tropical depression and was no longer weeks prior to Ike. tracked by the NHC, the AIR model in fact performed very well in capturing the effects of this storm. All three landfalling hurricanes arrived on U.S. shores as Category 2 storms on the Saffir-Simpson scale. Yet according This article traces the history of Hurricane Ike’s brief but to the latest estimates by ISO’s Property Claims Services unit, costly assault on the U.S. It also looks at how the AIR U.S.
    [Show full text]
  • Air Quality in North America's Most Populous City
    Atmos. Chem. Phys., 7, 2447–2473, 2007 www.atmos-chem-phys.net/7/2447/2007/ Atmospheric © Author(s) 2007. This work is licensed Chemistry under a Creative Commons License. and Physics Air quality in North America’s most populous city – overview of the MCMA-2003 campaign L. T. Molina1,2, C. E. Kolb3, B. de Foy1,2,4, B. K. Lamb5, W. H. Brune6, J. L. Jimenez7,8, R. Ramos-Villegas9, J. Sarmiento9, V. H. Paramo-Figueroa9, B. Cardenas10, V. Gutierrez-Avedoy10, and M. J. Molina1,11 1Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA, USA 2Molina Center for Energy and Environment, La Jolla, CA, USA 3Aerodyne Research, Inc., Billerica, MA, USA 4Saint Louis University, St. Louis, MO, USA 5Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman, WA, USA 6Department of Meteorology, Pennsylvania State University, University Park, PA, USA 7Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, CO, USA 8Cooperative Institute for Research in the Environmental Sciences (CIRES), Univ. of Colorado at Boulder, Boulder, CO, USA 9Secretary of Environment, Government of the Federal District, Mexico, DF, Mexico 10National Center for Environmental Research and Training, National Institute of Ecology, Mexico, DF, Mexico 11Department of Chemistry and Biochemistry, University of California at San Diego, San Diego, CA, USA Received: 22 February 2007 – Published in Atmos. Chem. Phys. Discuss.: 27 February 2007 Revised: 10 May 2007 – Accepted: 10 May 2007 – Published: 14 May 2007 Abstract. Exploratory field measurements in the Mexico 1 Introduction City Metropolitan Area (MCMA) in February 2002 set the stage for a major air quality field measurement campaign in 1.1 Air pollution in megacities the spring of 2003 (MCMA-2003).
    [Show full text]
  • Climatology, Variability, and Return Periods of Tropical Cyclone Strikes in the Northeastern and Central Pacific Ab Sins Nicholas S
    Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School March 2019 Climatology, Variability, and Return Periods of Tropical Cyclone Strikes in the Northeastern and Central Pacific aB sins Nicholas S. Grondin Louisiana State University, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Climate Commons, Meteorology Commons, and the Physical and Environmental Geography Commons Recommended Citation Grondin, Nicholas S., "Climatology, Variability, and Return Periods of Tropical Cyclone Strikes in the Northeastern and Central Pacific asinB s" (2019). LSU Master's Theses. 4864. https://digitalcommons.lsu.edu/gradschool_theses/4864 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. CLIMATOLOGY, VARIABILITY, AND RETURN PERIODS OF TROPICAL CYCLONE STRIKES IN THE NORTHEASTERN AND CENTRAL PACIFIC BASINS A Thesis Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Master of Science in The Department of Geography and Anthropology by Nicholas S. Grondin B.S. Meteorology, University of South Alabama, 2016 May 2019 Dedication This thesis is dedicated to my family, especially mom, Mim and Pop, for their love and encouragement every step of the way. This thesis is dedicated to my friends and fraternity brothers, especially Dillon, Sarah, Clay, and Courtney, for their friendship and support. This thesis is dedicated to all of my teachers and college professors, especially Mrs.
    [Show full text]
  • Hurricane and Tropical Storm
    State of New Jersey 2014 Hazard Mitigation Plan Section 5. Risk Assessment 5.8 Hurricane and Tropical Storm 2014 Plan Update Changes The 2014 Plan Update includes tropical storms, hurricanes and storm surge in this hazard profile. In the 2011 HMP, storm surge was included in the flood hazard. The hazard profile has been significantly enhanced to include a detailed hazard description, location, extent, previous occurrences, probability of future occurrence, severity, warning time and secondary impacts. New and updated data and figures from ONJSC are incorporated. New and updated figures from other federal and state agencies are incorporated. Potential change in climate and its impacts on the flood hazard are discussed. The vulnerability assessment now directly follows the hazard profile. An exposure analysis of the population, general building stock, State-owned and leased buildings, critical facilities and infrastructure was conducted using best available SLOSH and storm surge data. Environmental impacts is a new subsection. 5.8.1 Profile Hazard Description A tropical cyclone is a rotating, organized system of clouds and thunderstorms that originates over tropical or sub-tropical waters and has a closed low-level circulation. Tropical depressions, tropical storms, and hurricanes are all considered tropical cyclones. These storms rotate counterclockwise in the northern hemisphere around the center and are accompanied by heavy rain and strong winds (National Oceanic and Atmospheric Administration [NOAA] 2013a). Almost all tropical storms and hurricanes in the Atlantic basin (which includes the Gulf of Mexico and Caribbean Sea) form between June 1 and November 30 (hurricane season). August and September are peak months for hurricane development.
    [Show full text]
  • Assessing and Improving Cloud-Height Based Parameterisations of Global Lightning Flash Rate, and Their Impact on Lightning-Produced Nox and Tropospheric Composition
    https://doi.org/10.5194/acp-2020-885 Preprint. Discussion started: 2 October 2020 c Author(s) 2020. CC BY 4.0 License. Assessing and improving cloud-height based parameterisations of global lightning flash rate, and their impact on lightning-produced NOx and tropospheric composition 5 Ashok K. Luhar1, Ian E. Galbally1, Matthew T. Woodhouse1, and Nathan Luke Abraham2,3 1CSIRO Oceans and Atmosphere, Aspendale, 3195, Australia 2National Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Cambridge, UK 3Department of Chemistry, University of Cambridge, Cambridge, UK 10 Correspondence to: Ashok K. Luhar ([email protected]) Abstract. Although lightning-generated oxides of nitrogen (LNOx) account for only approximately 10% of the global NOx source, it has a disproportionately large impact on tropospheric photochemistry due to the conducive conditions in the tropical upper troposphere where lightning is mostly discharged. In most global composition models, lightning flash rates used to calculate LNOx are expressed in terms of convective cloud-top height via the Price and Rind (1992) (PR92) 15 parameterisations for land and ocean. We conduct a critical assessment of flash-rate parameterisations that are based on cloud-top height and validate them within the ACCESS-UKCA global chemistry-climate model using the LIS/OTD satellite data. While the PR92 parameterisation for land yields satisfactory predictions, the oceanic parameterisation underestimates the observed flash-rate density severely, yielding a global average of 0.33 flashes s-1 compared to the observed 9.16 -1 flashes s over the ocean and leading to LNOx being underestimated proportionally. We formulate new/alternative flash-rate 20 parameterisations following Boccippio’s (2002) scaling relationships between thunderstorm electrical generator power and storm geometry coupled with available data.
    [Show full text]
  • 6B.3 Synoptic Composites of the Extratropical Transition Lifecycle of North Atlantic Tropical Cyclones: Factors Determining Post-Transition Evolution
    6B.3 SYNOPTIC COMPOSITES OF THE EXTRATROPICAL TRANSITION LIFECYCLE OF NORTH ATLANTIC TROPICAL CYCLONES: FACTORS DETERMINING POST-TRANSITION EVOLUTION Robert E. Hart1, Jenni L. Evans2, and Clark Evans1 1Department of Meteorology, Florida State University 2Department of Meteorology, Pennsylvania State University 1. INTRODUCTION 2. DATA AND METHODOLOGY Over the past five years, the extratropical a. Datasets transition (ET) lifecycle has been defined based upon Storm composites performed here were satellite signatures (Klein et al. 2000) and objective based upon 1°×1° resolution Navy Operational measures of dynamic and thermal structure (Evans Global Atmospheric Prediction System (NOGAPS; and Hart 2003). Following ET, tropical cyclones Hogan et al. 1991) operational analyses for the period (TCs) can become explosive cold-core cyclones, 1998-2003. During these six years, 34 Atlantic TCs explosive warm-seclusion cyclones, or simply decay underwent resolvable ET as diagnosed within the as a cold-core cyclone (Hart 2003; Evans and Hart cyclone phase space (CPS) 2003). Each of these three evolution paths has (http://moe.met.fsu.edu/cyclonephase). dramatically different wind and precipitation field b. Methodology (Bosart et al. 2001), and ocean wave (Bowyer 2000; i. Normalizing the ET timeline Bowyer and Fogarty 2003) responses associated with The ET lifecycle defined in Evans and Hart it. Furthermore, the envelope of realized intensity is (2003) is used here, with the beginning of ET fundamentally related to the structure obtained after (labeled as TB) as the time when the storm becomes ET (Hart 2003), so incorrect forecasts of storm significantly asymmetric (B>10) and end of ET structure have the effect of also degrading the (labeled as TE) the time when the lower-tropospheric L intensity forecasts.
    [Show full text]
  • 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.
    [Show full text]