YaBeSH Engineering and Technology Library

    • Journals
    • PaperQuest
    • YSE Standards
    • YaBeSH
    • Login
    View Item 
    •   YE&T Library
    • AMS
    • Weather and Forecasting
    • View Item
    •   YE&T Library
    • AMS
    • Weather and Forecasting
    • View Item
    • All Fields
    • Source Title
    • Year
    • Publisher
    • Title
    • Subject
    • Author
    • DOI
    • ISBN
    Advanced Search
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Archive

    A WSR-88D Assessment of Tropical Cyclone Outer Rainband Tornadoes

    Source: Weather and Forecasting:;1997:;volume( 012 ):;issue: 003::page 479
    Author:
    Spratt, Scott M.
    ,
    Sharp, David W.
    ,
    Welsh, Pat
    ,
    Sandrik, Al
    ,
    Alsheimer, Frank
    ,
    Paxton, Charlie
    DOI: 10.1175/1520-0434(1997)012<0479:AWAOTC>2.0.CO;2
    Publisher: American Meteorological Society
    Abstract: As part of the National Weather Service (NWS) Modernization and Restructuring Program, WSR-88D (NEXRAD) Doppler radar installation has been completed at each Weather Service Office in Florida. Recently, this powerful new tool provided unique opportunities for Jacksonville, Tampa Bay, and Melbourne NEXRAD Weather Service Office personnel to investigate tropical cyclone (TC) rainbands for evidence of tornadogenesis. This study provides a radar-based analysis of known tornadic mesocyclones associated with two mature tropical cyclones that were not landfalling in the vicinity of the tornado occurrence, namely, Tropical Storm Gordon (1994) and Hurricane Allison (1995). Based on successful NEXRAD sampling strategies, detailed analyses of storm-scale reflectivity and velocity signatures are conducted in the context of establishing preliminary critical criteria for use in the tornado detection and warning process. Important characteristics were found to include detection of discrete, small diameter >50 dBZ echos collocated with storm-relative rotational velocities of 6.5?15 m s?1. Rotational features, although often subtle, were identifiable for an average of 30 min prior to tornado production, with total durations of 1?2 h. Near the time of tornado touchdown, the core diameter of the low-level circulation couplets contracted to approximately 1.85 km (1 n mi), leading to an associated increase of shear across the circulation to 0.010 s?1 or greater. A comparison between the well-studied Great Plains tornadic supercell and the observed TC-tornado cells revealed a common trait of persistence. While the average depth of rotation associated with the TC-tornado cells (3.5 km) was much more shallow than their midwest counterparts, the ratio of depth of rotation to storm top were comparable. However, the shallow depth and weaker detectable rotation of the TC (tornadic) mesocyclones greatly reduced the detection capability of the current WSR-88D mesocyclone algorithm when compared to identification of traditional supercells. Based upon the analyzed data, the authors offer several recommendations to assist operational radar meteorologists with the challenging task of detecting outer rainband tornadoes. Additionally, the authors propose a new WSR-88D scan strategy (volume coverage pattern, VCP) that would provide additional low-level slices in lieu of several current upper-elevation angles. This new VCP would facilitate improved vertical sampling at lower heights where TC mesoscale circulations are most likely to be detected.
    • Download: (675.5Kb)
    • Show Full MetaData Hide Full MetaData
    • Item Order
    • Go To Publisher
    • Price: 5000 Rial
    • Statistics

      A WSR-88D Assessment of Tropical Cyclone Outer Rainband Tornadoes

    URI
    http://yetl.yabesh.ir/yetl1/handle/yetl/4166212
    Collections
    • Weather and Forecasting

    Show full item record

    contributor authorSpratt, Scott M.
    contributor authorSharp, David W.
    contributor authorWelsh, Pat
    contributor authorSandrik, Al
    contributor authorAlsheimer, Frank
    contributor authorPaxton, Charlie
    date accessioned2017-06-09T14:53:25Z
    date available2017-06-09T14:53:25Z
    date copyright1997/09/01
    date issued1997
    identifier issn0882-8156
    identifier otherams-2903.pdf
    identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4166212
    description abstractAs part of the National Weather Service (NWS) Modernization and Restructuring Program, WSR-88D (NEXRAD) Doppler radar installation has been completed at each Weather Service Office in Florida. Recently, this powerful new tool provided unique opportunities for Jacksonville, Tampa Bay, and Melbourne NEXRAD Weather Service Office personnel to investigate tropical cyclone (TC) rainbands for evidence of tornadogenesis. This study provides a radar-based analysis of known tornadic mesocyclones associated with two mature tropical cyclones that were not landfalling in the vicinity of the tornado occurrence, namely, Tropical Storm Gordon (1994) and Hurricane Allison (1995). Based on successful NEXRAD sampling strategies, detailed analyses of storm-scale reflectivity and velocity signatures are conducted in the context of establishing preliminary critical criteria for use in the tornado detection and warning process. Important characteristics were found to include detection of discrete, small diameter >50 dBZ echos collocated with storm-relative rotational velocities of 6.5?15 m s?1. Rotational features, although often subtle, were identifiable for an average of 30 min prior to tornado production, with total durations of 1?2 h. Near the time of tornado touchdown, the core diameter of the low-level circulation couplets contracted to approximately 1.85 km (1 n mi), leading to an associated increase of shear across the circulation to 0.010 s?1 or greater. A comparison between the well-studied Great Plains tornadic supercell and the observed TC-tornado cells revealed a common trait of persistence. While the average depth of rotation associated with the TC-tornado cells (3.5 km) was much more shallow than their midwest counterparts, the ratio of depth of rotation to storm top were comparable. However, the shallow depth and weaker detectable rotation of the TC (tornadic) mesocyclones greatly reduced the detection capability of the current WSR-88D mesocyclone algorithm when compared to identification of traditional supercells. Based upon the analyzed data, the authors offer several recommendations to assist operational radar meteorologists with the challenging task of detecting outer rainband tornadoes. Additionally, the authors propose a new WSR-88D scan strategy (volume coverage pattern, VCP) that would provide additional low-level slices in lieu of several current upper-elevation angles. This new VCP would facilitate improved vertical sampling at lower heights where TC mesoscale circulations are most likely to be detected.
    publisherAmerican Meteorological Society
    titleA WSR-88D Assessment of Tropical Cyclone Outer Rainband Tornadoes
    typeJournal Paper
    journal volume12
    journal issue3
    journal titleWeather and Forecasting
    identifier doi10.1175/1520-0434(1997)012<0479:AWAOTC>2.0.CO;2
    journal fristpage479
    journal lastpage501
    treeWeather and Forecasting:;1997:;volume( 012 ):;issue: 003
    contenttypeFulltext
    DSpace software copyright © 2002-2015  DuraSpace
    نرم افزار کتابخانه دیجیتال "دی اسپیس" فارسی شده توسط یابش برای کتابخانه های ایرانی | تماس با یابش
    yabeshDSpacePersian
     
    DSpace software copyright © 2002-2015  DuraSpace
    نرم افزار کتابخانه دیجیتال "دی اسپیس" فارسی شده توسط یابش برای کتابخانه های ایرانی | تماس با یابش
    yabeshDSpacePersian