A Case Study of Severe Storm Development along a Dryline within a Synoptically Active Environment. Part II: Multiple Boundaries and Convective Initiation

Abstract A dryline that occurred on 16 May 1991 within a synoptically active environment is examined in detail using research aircraft, radar, surface, satellite, and upper air observations. The work focuses on multiple boundaries in the dryline environment and initiation of tornadic storms in two along-line areas. Aircraft measurements in the boundary layer reveal that both the east–west extent of moisture gradients and the number of regions containing large moisture gradients vary in the along-dryline direction. Aircraft penetrations of thinlines observed in clear air return from radar reveal that all thinlines are associated with convergence and a moisture gradient, and that more distinct thinlines are associated with stronger convergence. However, significant moisture gradients are not always associated with either thinlines or convergent signatures. Convective clouds on this day formed at the dryline rather than significantly east of the dryline. The three thunderstorm cells that occurred in east-cen...

[1]  T. M. Crawford,et al.  Characteristics of Dryline Passage during COPS-91 , 1997 .

[2]  Tetsuya Theodore. Fujita,et al.  The Lubbock Tornadoes: A Study of Suction Spots , 1970 .

[3]  T. Clark,et al.  The Denver Cyclone. Part II: Interaction with the Convective Boundary Layer , 1991 .

[4]  Tammy M. Weckwerth,et al.  Horizontal Convective Rolls: Determining the Environmental Conditions Supporting their Existence and Characteristics , 1997 .

[5]  James W. Wilson,et al.  Initiation of Convective Storms at Radar-Observed Boundary-Layer Convergence Lines , 1986 .

[6]  William L. Smith,et al.  GHIS—The GOES High-Resolution Interferometer Sounder , 1990 .

[7]  T. M. Crawford,et al.  Severe Thunderstorm Development in Relation to Along-Dryline Variability: A Case Study , 1997 .

[8]  C. Ziegler,et al.  Observations of the Finescale Structure of a Dryline during VORTEX 95 , 1998 .

[9]  J. Caskey.  ENVIRONMENTAL AND THUNDERSTORM STRUCTURES AS SHOWN BY NATIONAL SEVERE STORMS PROJECT OBSERVATIONS IN SPRING 1960 AND 1961 , 1962 .

[10]  David J. Stensrud,et al.  Observed Effects of Landscape Variability on Convective Clouds , 1990 .

[11]  R. Wakimoto,et al.  The Relationship between Radar Reflectivities and Clouds Associated with Horizontal Roll Convection on 8 August 1982 , 1989 .

[12]  Gary L. Achtemeier,et al.  The Use of Insects as Tracers for “Clear-Air” Boundary-Layer Studies by Doppler Radar , 1991 .

[13]  Fred V. Brock,et al.  Portable Automated Mesonet II , 1986 .

[14]  Steven E. Koch,et al.  The Evolution of an Oklahoma Dryline. Part I: A Meso- and Subsynoptic-Scale Analysis. , 1982 .

[15]  James W. Wilson,et al.  Thunderstorm Initiation, Organization, and Lifetime Associated with Florida Boundary Layer Convergence Lines , 1997 .

[16]  Peter H. Hildebrand,et al.  ELDORA observations during VORTEX 95 , 1996 .

[17]  Staff Members.  ENVIRONMENTAL AND THUNDERSTORM STRUCTURES AS SHOWN BY NATIONAL SEVERE STORMS PROJECT OBSERVATIONS IN SPRING 1960 AND 1961 , 1963 .

[18]  T. W. Horst,et al.  An Observational Study of the Evolution of Horizontal Convective Rolls , 1999 .

[19]  Mobile Sounding Observations of a Thunderstorm near the Dryline: The Gruver, Texas Storm Complex of 25 May 1987 , 1989 .

[20]  Roger M. Wakimoto,et al.  Observations of the Sea-Breeze Front during CaPE. Part I: Single-Doppler, Satellite, and Cloud Photogrammetry Analysis , 1994 .

[21]  R. Arritt,et al.  Scaling Evaluation of the Effect of Surface Characteristics on Potential for Deep Convection over Uniform Terrain , 1995 .

[22]  D. Parsons,et al.  The Finescale Structure of a West Texas Dryline , 1991 .

[23]  S H Melfi,et al.  Remote measurements of the atmosphere using Raman scattering. , 1972, Applied optics.

[24]  Steven K. Krueger,et al.  The Role of Boundary-Layer Convergence Zones and Horizontal Rolls in the Initiation of Thunderstorms: A Case Study , 1992 .

[25]  V. E. Derr,et al.  Atmospheric water vapor measurement by Raman Lidar , 1971 .

[26]  Howard B. Bluestein,et al.  Principles of kinematics and dynamics , 1992 .

[27]  Tammy M. Weckwerth,et al.  Observations of the Sea-Breeze Front during CaPE. Part II: Dual-Doppler and Aircraft Analysis , 1995 .

[28]  W. D. Rust,et al.  Testing a mobile version of a Cross-Chain LORAN Atmospheric (M-CLASS) Sounding System , 1990 .

[29]  T. M. Crawford,et al.  A Case Study of Severe Storm Development along a Dryline within a Synoptically Active Environment. Part I: Dryline Motion and an Eta Model Forecast , 2001 .

[30]  I. Katz,et al.  Probing the clear atmosphere with high power, high resolution radars , 1969 .

[31]  Jothiram Vivekanandan,et al.  Boundary Layer Clear-Air Radar Echoes: Origin of Echoes and Accuracy of Derived Winds , 1994 .

[32]  C. Weiss.  Airborne Doppler analysis of a dryline-outflow boundary intersection and subsequent convection , 2000 .

[33]  Erik N. Rasmussen,et al.  The Initiation of Moist Convection at the Dryline: Forecasting Issues from aCase Study Perspective , 1998 .

[34]  Radar Detection of the Sea Breeze. , 1960 .

[35]  Gary R. Woodall,et al.  Mobile Sounding Observations of a Tornadic Storm near the Dryline: The Canadian, Texas Storm of 7 May 1986 , 1988 .

[36]  Conrad L. Ziegler,et al.  An Observational Study of the Dryline , 1993 .