The Genesis of Hurricane Guillermo: TEXMEX Analyses and a Modeling Study

Abstract The transformation of a mesoscale convective system into Hurricane Guillermo was captured by aircraft and Doppler wind data during the Tropical Experiment in Mexico. The early phase of the system evolves in a way very similar to previously documented mesoscale convective systems, with a midlevel mesocyclone developing in the stratiform precipitation region. More unusually, the cyclone extends to low altitudes: A weak cyclone is discernable even in the 300-m altitude wind field. After another day of evolution, a small, surface-based warm-core cyclone is observed to develop within the relatively cold air associated with the mesocyclone aloft. This mesocyclone develops into a hurricane over the subsequent day. A nonhydrostatic, axisymmetric numerical model is used to explore the evolution of the initially cold-core, midlevel vortex into a tropical cyclone. A mesoscale, midlevel “showerhead” is switched on in an initially quiescent, tropical atmosphere overlying a warm ocean surface. Evaporation of t...

[1]  J. Gamache,et al.  Further Analysis of the Composite Wind and Thermodynamic Structure of the 12 September GATE Squall Line , 1985 .

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

[3]  J. Fritsch,et al.  Mesoscale convective complexes in Africa , 1993 .

[4]  Kerry A. Emanuel,et al.  The Behavior of a Simple Hurricane Model Using a Convective Scheme Based on Subcloud-Layer Entropy Equilibrium , 1995 .

[5]  D. Raymond,et al.  A Theory for Long-Lived Mesoscale Convective Systems , 1990 .

[6]  J. Kain,et al.  Warm Core Vortex Amplification over Land , 1994 .

[7]  R. Maddox,et al.  Midlevel Cyclonic Vortices Generated by Mesoseale Convective Systems , 1991 .

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

[9]  M. Bister.  Development of tropical cyclones from mesoscale convective systems , 1996 .

[10]  G. Holland,et al.  On the Formation of AMEX Tropical Cyclones Irma and Jason , 1990 .

[11]  Mark Williams,et al.  Satellite-Observed Characteristics of Winter Monsoon Cloud Clusters , 1987 .

[12]  R. Elsberry,et al.  A global view of tropical cyclones , 1987 .

[13]  David J. Knight,et al.  Potential Vorticity, Easterly Waves, and Eastern Pacific Tropical Cyclogenesis , 1997 .

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

[15]  Shuyi S. Chen.  A numerical study of the genesis of extratropical convective mesovortices , 1993 .

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

[17]  Harry H. Hendon,et al.  The Relationship Between Tropical Cyclones of the Western Pacific and Indian Oceans and the Madden-J , 1994 .

[18]  C. Davis,et al.  Balanced Dynamics of Mesoscale Vortices Produced in Simulated Convective Systems , 1994 .

[19]  R. Gall,et al.  On a mechanism for orographic triggering of tropical cyclones in the Eastern North Pacific , 1991 .

[20]  Robert W. Burpee.  The Hurricane and Its Impact , 1982 .

[21]  J. Michael Fritsch,et al.  Mesoscale Convective Complexes in the Americas , 1987 .

[22]  John F. Gamache,et al.  Comparison of Three Airborne Doppler Sampling Techniques with Airborne In Situ Wind Observations in Hurricane Gustav (1990) , 1995 .

[23]  L. Bosart,et al.  The Johnstown Flood of July 1977: A Long-Lived Convective System , 1981 .

[24]  Raymond M. Zehr,et al.  Observational Analysis of Tropical Cyclone Formation. Part II: Comparison of Non-Developing versus Developing Systems , 1981 .

[25]  J. Zehnder,et al.  Orographic Influence on the Synoptic-Scale Circulations Associated with the Genesis of Hurricane Guillermo (1991) , 1997 .

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

[27]  D. H. Reilly.  On the role of upper-tropospheric potential vorticity advection in tropical cyclone formation : case studies from 1991 , 1992 .

[28]  D. W. Bargen,et al.  Interactive radar velocity unfolding , 1980 .