Tropical Cyclone Formation in a Sheared Environment: A Case Study

Abstract The development of Hurricane Danny (1997) from depression to hurricane was examined using cloud-to-ground lightning data, reconnaissance aircraft data, and satellite imagery. Vertical wind shear between 850 and 200 hPa of 5–11 m s−1 produced persistent downshear convective outbreaks that became progressively more intense and closer to the center during the development. Early in the period the storm intensified steadily in the presence of this downshear convection. During the last and most intense outbreak, a second vortex appeared to develop within the convection. Evidence is presented that the new downshear vortex became the dominant vortex and absorbed the original. Based on these events, it is hypothesized that the presence of moderate vertical wind shear accelerated the early development process. Equivalent potential temperature fields within 500 m of the surface were examined. Only well after the period of vortex interaction did the characteristic mature tropical cyclone radial profile of eq...

[1]  Kristen L. Corbosiero,et al.  The Relationship between Storm Motion, Vertical Wind Shear, and Convective Asymmetries in Tropical Cyclones , 2003 .

[2]  P. Jamason,et al.  Performance evaluation of the U.S. National Lightning , 1998 .

[3]  L. Bosart,et al.  Baroclinically Induced Tropical Cyclogenesis , 2003 .

[4]  J. Molinari,et al.  A Composite Study of the Interactions between Tropical Cyclones and Upper-Tropospheric Troughs , 2001 .

[5]  J. Kossin,et al.  Mesovortices in Hurricane Isabel , 2004 .

[6]  Christopher A. Davis.  Numerical simulations of the genesis of Hurricane Diana (1984) [presentation] , 2001 .

[7]  R. C. Sutcliffe,et al.  A contribution to the problem of development , 1947 .

[8]  Kenneth L. Cummins,et al.  A Combined TOA/MDF Technology Upgrade of the U.S. National Lightning Detection Network , 1998 .

[9]  L. Bosart,et al.  Tropical Storm Formation in a Baroclinic Environment , 1991 .

[10]  P. Jamason,et al.  Performance evaluation of the U.S. National Lightning Detection , 1998 .

[11]  B. Farrell,et al.  Tropical Cyclone Formation , 1993 .

[12]  M. Montgomery,et al.  Tropical Cyclogenesis via Convectively Forced Vortex Rossby Waves in a Three-Dimensional Quasigeostrophic Model , 1998 .

[13]  Kerry Emanuel,et al.  An Air-Sea Interaction Theory for Tropical Cyclones. Part I: Steady-State Maintenance , 1986 .

[14]  R. Orville,et al.  Cloud-to-ground lightning in tropical cyclones: A study of Hurricanes Hugo (1989) and Jerry (1989) , 1994 .

[15]  K. Emanuel.  The Finite-Amplitude Nature of Tropical Cyclogenesis , 1989 .

[16]  Richard E. Orville,et al.  Calibration of a magnetic direction finding network using measured triggered lightning return stroke peak currents , 1991 .

[17]  E. Zipser,et al.  Reflectivity, Ice Scattering, and Lightning Characteristics of Hurricane Eyewalls and Rainbands. Part I: Quantitative Description , 2002 .

[18]  Roger K. Smith.  A simple model of the hurricane boundary layer , 2003 .

[19]  K. Corbosiero,et al.  The Effects of Vertical Wind Shear on the Distribution of Convection in Tropical Cyclones , 2002 .

[20]  K. Emanuel,et al.  An Air–Sea Interaction Theory for Tropical Cyclones. Part II: Evolutionary Study Using a Nonhydrostatic Axisymmetric Numerical Model , 1987 .

[21]  M. Montgomery,et al.  A New Look at the Problem of Tropical Cyclones in Vertical Shear Flow: Vortex Resiliency , 2004 .

[22]  H. Hawkins,et al.  The Structure of a Small, Intense Hurricane—Inez 1966 , 1976 .

[23]  M. Montgomery,et al.  Three-Dimensional Alignment and Corotation of Weak, TC-like Vortices via Linear Vortex Rossby Waves , 2001 .

[24]  Robert W. Burpee,et al.  Vertical Motion Characteristics of Tropical Cyclones Determined with Airborne Doppler Radial Velocities , 1996 .

[25]  Alan Gadian,et al.  Relationships between lightning activity and various thundercloud parameters: satellite and modelling studies , 1999 .

[26]  Elizabeth A. Ritchie,et al.  Scale interactions during the formation of typhoon irving , 1997 .

[27]  W. M. Gray,et al.  Flight-Level Thermodynamic Instrument Wetting Errors in Hurricanes. Part I: Observations , 2002 .

[28]  W. M. Gray,et al.  Flight-Level Thermodynamic Instrument Wetting Errors in Hurricanes. Part II: Implications , 2001 .

[29]  V. P. Idone,et al.  Cloud‐to‐ground lightning in Hurricane Andrew , 1994 .

[30]  Lance F. Bosart,et al.  The Role of Synoptic-Scale Flow during Tropical Cyclogenesis over the North Atlantic Ocean , 2000 .

[31]  M. Montgomery,et al.  Tropical Cyclogenesis via Convectively Forced Vortex Rossby Waves in a Shallow Water Primitive Equation Model , 2001 .

[32]  M. Montgomery,et al.  Tropical Cyclone Evolution via Potential Vorticity Anomalies in a Three-Dimensional Balance Model , 2000 .

[33]  J. Molinari,et al.  External Influences on Hurricane Intensity. Part III: Potential Vorticity Structure , 1995 .

[34]  V. P. Idone,et al.  Convective Structure of Hurricanes as Revealed by Lightning Locations , 1999 .

[35]  Frank D. Marks,et al.  Inner Core Structure of Hurricane Alicia from Airborne Doppler Radar Observations , 1987 .

[36]  Robert A. Black,et al.  Electrification of the hurricane , 1999 .

[37]  Kerry A. Emanuel,et al.  The Genesis of Hurricane Guillermo: TEXMEX Analyses and a Modeling Study , 1997 .

[38]  K. Blackwell.  The Evolution of Hurricane Danny (1997) at Landfall: Doppler-Observed Eyewall Replacement, Vortex Contraction/Intensification, and Low-Level Wind Maxima , 2000 .

[39]  E. Zipser,et al.  Reflectivity, Ice Scattering, and Lightning Characteristics of Hurricane Eyewalls and Rainbands. Part II: Intercomparison of Observations , 2002 .

[40]  Christopher A. Davis,et al.  Numerical Simulations of the Genesis of Hurricane Diana (1984). Part I: Control Simulation , 2000 .

[41]  A. J. Waters,et al.  Images in Weather Forecasting a Practical Guide for Interpreting Satellite and Radar Imagery , 1995 .

[42]  J. Molinari,et al.  External Influences on Hurricane Intensity. Part I: Outflow Layer Eddy Angular Momentum Fluxes. , 1989 .

[43]  Elizabeth A. Ritchie,et al.  Effects of Vertical Wind Shear on the Intensity and Structure of Numerically Simulated Hurricanes , 2001 .

[44]  W. D. Rust,et al.  The electrical nature of storms , 1998 .

[45]  Jong‐Jin Baik,et al.  Upper-level eddy angular momentum fluxes and tropical cyclone intensity change , 1993 .

[46]  Lucio López Cavazos,et al.  Case‐studies of developing east Pacific easterly waves , 1998 .

[47]  E. Zipser,et al.  The Vertical Profile of Radar Reflectivity of Convective Cells: A Strong Indicator of Storm Intensity and Lightning Probability? , 1994 .

[48]  Mark D. Powell,et al.  The HRD real-time hurricane wind analysis system , 1998 .

[49]  K. Emanuel.  Some Aspects of Hurricane Inner-Core Dynamics and Energetics , 1997 .

[50]  Elizabeth A. Ritchie,et al.  Mesoscale Interactions in Tropical Cyclone Genesis , 1997 .

[51]  R. Simpson.  On The Computation of Equivalent Potential Temperature , 1978 .

[52]  Mark DeMaria,et al.  The Effect of Vertical Shear on Tropical Cyclone Intensity Change , 1996 .