• Bluestein, H. B., and M. H. Jain, 1985: Formation of mesoscale lines of precipitation: Severe squall lines in Oklahoma during the spring. J. Atmos. Sci.,42, 1711–1732.

  • Bretherton, C. S., and P. K. Smolarkiewicz, 1989: Gravity waves, compensating subsidence, and detrainment around cumulus clouds. J. Atmos. Sci.,46, 740–759.

  • Cotton, W. R., and R. A. Anthes, 1989: Storm and Cloud Dynamics. Academic Press, 883 pp.

  • Cram, J. M., R. A. Pielke, and W. R. Cotton, 1992a: Numerical simulation and analysis of a prefrontal squall line. Part I: Observations and basic simulation results. J. Atmos. Sci.,49, 189–208.

  • ——, ——, and ——, 1992b: Numerical simulation and analysis of a prefrontal squall line. Part I: Propagation of the squall line as an internal gravity wave. J. Atmos. Sci.,49, 209–225.

  • Crook, N. A., and M. W. Moncrieff, 1988: The effect of large-scale convergence on the generation and maintenance of deep moist convection. J. Atmos. Sci.,45, 3606–3624.

  • Fortune, M. A., W. R. Cotton, and R. L. McAnelly, 1992: Frontal wave–like evolution in some mesoscale convective complexes. Mon. Wea. Rev.,120, 1279–1300.

  • Fovell, R. G., and Y. Ogura, 1989: Effect of vertical wind shear on numerically simulated multicell storm structure. J. Atmos. Sci.,46, 3144–3176.

  • Fritsch, J. M., 1975: Cumulus dynamics: Local compensating subsidence and its implications for cumulus parameterization. Pure Appl. Geophys.,113, 851–867.

  • Houze, R. A., Jr., S. A. Rutledge, M. I. Biggerstaff, and B. F. Smull, 1989: Interpretation of Doppler weather radar displays of midlatitude mesoscale convective systems. Bull. Amer. Meteor. Soc.,70, 608–619.

  • ——, B. F. Smull, and P. Dodge, 1990: Mesoscale organization of springtime rainstorms in Oklahoma. Mon. Wea. Rev.,118, 613–654.

  • Johns, R. H., and W. D. Hirt, 1987: Derechos: Widespread convectively induced windstorms. Wea. Forecasting,2, 32–49.

  • Kennedy, P. C., and S. A. Rutledge, 1995: Dual-Doppler and multiparameter radar observations of a bow-echo hailstorm. Mon. Wea. Rev.,123, 921–943.

  • Lafore, J.-P., and M. W. Moncrieff, 1989: A numerical investigation of the organization and interaction of the convective and stratiform regions of tropical squall lines. J. Atmos. Sci.,46, 521–544.

  • Leary, C. A., and R. A. Houze Jr., 1979a: The structure and evolution of convection in a tropical cloud cluster. J. Atmos. Sci.,36, 437–457.

  • ——, and ——, 1979b: Melting and evaporation of hydrometeors in precipitation from the anvil clouds of deep tropical convection. J. Atmos. Sci.,36, 669–679.

  • Maddox, R. A., 1980: Mesoscale convective complexes. Bull. Amer. Meteor. Soc.,61, 1374–1387.

  • ——, 1981: The structure and life-cycle of midlatitude mesoscale convective complexes. Dept. Atmospheric Sciences Paper 336, 331 pp. [Available from Department Atmospheric Sciences, Colorado State University, Fort Collins, CO 80523.].

  • Mapes, B. E., 1993: Gregarious tropical convection. J. Atmos. Sci.,50, 2026–2037.

  • McAnelly, R. L., and W. R. Cotton, 1986: Meso-β-scale characteristics of an episode of meso-α-scale convective complexes. Mon. Wea. Rev.,114, 1740–1770.

  • ——, and ——, 1992: Early growth of mesoscale convective complexes: A meso-β-scale cycle of convective precipitation? Mon. Wea. Rev.,120, 1851–1877.

  • Miller, L. J., C. G. Mohr, and A. J. Weinheimer, 1986: The simple rectification to Cartesian space of folded radial velocities from Doppler radar sampling. J. Atmos. Oceanic Technol.,3, 162–174.

  • Mohr, C. G., L. J. Miller, R. L. Vaughan, and H. W. Frank, 1986: The merger of mesoscale datasets into a common Cartesian format for efficient and systematic analyses. J. Atmos. Oceanic Technol.,3, 143–161.

  • Nachamkin, J. E., R. L. McAnelly, and W. R. Cotton, 1994: An observational analysis of a developing mesoscale convective complex. Mon. Wea. Rev.,122, 1168–1188.

  • Nicholls, M. E., R. A. Pielke, and W. R. Cotton, 1991: Thermally forced gravity waves in an atmosphere at rest. J. Atmos. Sci.,48, 1869–1884.

  • Oye, D., and M. Case, 1992: REORDER—A program for gridding radar data: Installation and use manual for the UNIX version, 22 pp. [Available from National Center for Atmospheric Research, Field Observing Facility, P.O. Box 3000, Boulder, CO 80307.].

  • Oye, R., and R. Carbone, 1981: Interactive Doppler editing software. Preprints, 20th Conf. on Radar Meteorology, Boston, MA, Amer. Meteor. Soc., 683–689.

  • Pandya, R., D. Duran, and C. Bretherton, 1993: Comments on “Thermally forced gravity waves in an atmosphere at rest.” J. Atmos. Sci.,50, 4097–4101.

  • Pratte, J. F., J. H. Van Andel, D. G. Ferraro, R. W. Gagnon, S. M. Maher, and G. L. Blair, 1991: NCAR’s mile high meteorological radar. Preprints, 25th Conf. on Radar Meteorology, Paris, France, Amer. Meteor. Soc., 863–866.

  • Rasmussen, E. N., and S. A. Rutledge, 1993: Evolution of quasi-two-dimensional squall lines. Part I: Kinematic and reflectivity structure. J. Atmos. Sci.,50, 2584–2606.

  • Raymond, D. J., 1983: Wave-CISK in mass-flux form. J. Atmos. Sci.,40, 2561–2572.

  • ——, 1984: A wave-CISK model of squall lines. J. Atmos. Sci.,41, 1946–1958.

  • ——, 1986: Prescribed heating of a stratified atmosphere as a model for moist convection. J. Atmos. Sci.,43, 1101–1111.

  • ——, 1987: A forced gravity wave model of self-organizing convection. J. Atmos. Sci.,44, 3528–3543.

  • Rotunno, R., J. B. Klemp, and M. L. Weisman, 1988: A theory for strong, long-lived squall lines. J. Atmos. Sci.,45, 463–485.

  • Rutledge, S. A., and R. A. Houze Jr., 1987: A diagnostic modelling study of the trailing stratiform region of a midlatitude squall line. J. Atmos. Sci.,44, 2640–2656.

  • ——, P. C. Kennedy, and D. A. Brunkow, 1993: Use of the CSU-CHILL radar in radar meteorology education at Colorado State University. Bull. Amer. Meteor. Soc.,74, 25–31.

  • Schmidt, J. M., and W. R. Cotton, 1989: A High Plains squall line associated with severe surface winds. J. Atmos. Sci.,46, 281–302.

  • ——, and ——, 1990: Interactions between upper and lower tropospheric gravity waves on squall line structure and maintenance. J. Atmos. Sci.,47, 1205–1222.

  • Scott, J. D., and S. A. Rutledge, 1995: Doppler radar observations of an asymmetric mesoscale convective system and associated vortex couplet. Mon. Wea. Rev.,123, 3437–3457.

  • Smull, B. F., and J. A. Augustine, 1993: Multiscale analysis of a mature mesoscale convective system. Mon. Wea. Rev.,121, 103–132.

  • Stensrud, D. K., and J. M. Fritsch, 1993: Mesoscale convective systems on weakly forced large-scale environments. Part I: Observations. Mon. Wea. Rev.,121, 3326–3344.

  • Stumpf, G. J., R. H. Johnson, and B. F. Smull, 1991: The wake low in a midlatitude mesoscale convective system having complex convective organization. Mon. Wea. Rev.,119, 134–158.

  • Thorpe, A. J., M. J. Miller, and M. W. Moncrieff, 1982: Two-dimensional convection in non-constant shear: A model of mid-latitude squall lines. Quart. J. Roy. Meteor. Soc.,108, 739–762.

  • Trier, S. B., and D. B. Parsons, 1993: Evolution of environmental conditions preceding the development of a nocturnal mesoscale convective complex. Mon. Wea. Rev.,121, 1078–1098.

  • Tripoli, G., and W. R. Cotton, 1989a: Numerical study of an observed orogenic mesoscale convective system. Part 1: Simulated genesis and comparison with observations. Mon. Wea. Rev.,117, 273–304.

  • ——, and ——, 1989b: Numerical study of an observed orogenic mesoscale convective system. Part 2: Analysis of governing dynamics. Mon. Wea. Rev.,117, 305–328.

  • Verlinde, J., and W. R. Cotton, 1990: A mesoscale vortex couplet observed in the trailing anvil of a multicellular convective complex. Mon. Wea. Rev.,118, 993–1010.

  • Weisman, M. L., 1992: The role of convectively generated rear-inflow jets in the evolution of long-lived mesoconvective systems. J. Atmos. Sci.,49, 1826–1847.

  • ——, 1993: The genesis of severe, long-lived bow echoes. J. Atmos. Sci.,50, 645–670.

  • ——, J. B. Klemp, and R. Rotunno, 1988: Structure and evolution of numerically simulated squall lines. J. Atmos. Sci.,45, 1990–2013.

  • Zipser, E. J., 1982: Use of a conceptual model of the life-cycle of mesoscale convective systems to improve very-short-range forecasts. Nowcasting, K. A. Browning, Ed., Academic Press, 191–204.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 108 45 5
PDF Downloads 79 39 4

Upscale Evolution of MCSs: Doppler Radar Analysis and Analytical Investigation

Ray L. McAnellyDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by Ray L. McAnelly in
Current site
Google Scholar
PubMed
Close
,
Jason E. NachamkinDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by Jason E. Nachamkin in
Current site
Google Scholar
PubMed
Close
,
William R. CottonDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by William R. Cotton in
Current site
Google Scholar
PubMed
Close
, and
Melville E. NichollsDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by Melville E. Nicholls in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The development of two small mesoscale convective systems (MCSs) in northeastern Colorado is investigated via dual-Doppler radar analysis. The first system developed from several initially isolated cumulonimbi, which gradually coalesced into a minimal MCS with relatively little stratiform precipitation. The second system developed more rapidly along an axis of convection and generated a more extensive and persistent stratiform echo and MCS cloud shield. In both systems, the volumetric precipitation rate exhibited an early meso-β-scale convective cycle (a maximum and subsequent minimum), followed by reintensification into a modest mature stage. This sequence is similar to that noted previously in the developing stage of larger MCSs by . They speculated that the early meso-β convective cycle is a characteristic feature of development in many MCSs that is dynamically linked to a rather abrupt transition toward mature stage structure. This study presents kinematic evidence in support of this hypothesis for these cases, as derived from dual-Doppler radar analyses over several-hour periods. Mature stage MCS characteristics such as deepened low- to midlevel convergence and mesoscale descent developed fairly rapidly, about 1 h after the early meso-β convective maximum.

The dynamic linkage between the meso-β convective cycle and evolution toward mature structure is examined with a simple analytical model of the linearized atmospheric response to prescribed heating. Heating functions that approximate the temporal and spatial characteristics of the meso-β convective cycle are prescribed. The solutions show that the cycle forces a response within and near the thermally forced region that is consistent with the observed kinematic evolution in the MCSs. The initial response to an intensifying convective ensemble is a self-suppressing mechanism that partially explains the weakening after a meso-β convective maximum. A lagged response then favors reintensification and areal growth of the weakened ensemble. A conceptual model of MCS development is proposed whereby the early meso-β convective cycle and the response to it are hypothesized to act as a generalized forcing–feedback mechanism that helps explain the upscale growth of a convective ensemble into an organized MCS.

Corresponding author address: Ray L. McAnelly, Dept. of Atmospheric Science, Colorado State University, Fort Collins, CO 80523-1371.

Email: raymc@woxof.atmos.coloState.edu

Abstract

The development of two small mesoscale convective systems (MCSs) in northeastern Colorado is investigated via dual-Doppler radar analysis. The first system developed from several initially isolated cumulonimbi, which gradually coalesced into a minimal MCS with relatively little stratiform precipitation. The second system developed more rapidly along an axis of convection and generated a more extensive and persistent stratiform echo and MCS cloud shield. In both systems, the volumetric precipitation rate exhibited an early meso-β-scale convective cycle (a maximum and subsequent minimum), followed by reintensification into a modest mature stage. This sequence is similar to that noted previously in the developing stage of larger MCSs by . They speculated that the early meso-β convective cycle is a characteristic feature of development in many MCSs that is dynamically linked to a rather abrupt transition toward mature stage structure. This study presents kinematic evidence in support of this hypothesis for these cases, as derived from dual-Doppler radar analyses over several-hour periods. Mature stage MCS characteristics such as deepened low- to midlevel convergence and mesoscale descent developed fairly rapidly, about 1 h after the early meso-β convective maximum.

The dynamic linkage between the meso-β convective cycle and evolution toward mature structure is examined with a simple analytical model of the linearized atmospheric response to prescribed heating. Heating functions that approximate the temporal and spatial characteristics of the meso-β convective cycle are prescribed. The solutions show that the cycle forces a response within and near the thermally forced region that is consistent with the observed kinematic evolution in the MCSs. The initial response to an intensifying convective ensemble is a self-suppressing mechanism that partially explains the weakening after a meso-β convective maximum. A lagged response then favors reintensification and areal growth of the weakened ensemble. A conceptual model of MCS development is proposed whereby the early meso-β convective cycle and the response to it are hypothesized to act as a generalized forcing–feedback mechanism that helps explain the upscale growth of a convective ensemble into an organized MCS.

Corresponding author address: Ray L. McAnelly, Dept. of Atmospheric Science, Colorado State University, Fort Collins, CO 80523-1371.

Email: raymc@woxof.atmos.coloState.edu

Save