• Brown, R. G., , and Zhang C. , 1997: Variability of midtropospheric moisture and its effect on cloud-top height distribution during TOGA COARE. J. Atmos. Sci., 54 , 27602774.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Browning, K. A., 1997: The dry intrusion perspective of extra-tropical cyclone development. Meteor. Appl., 4 , 317324.

  • Browning, K. A., , and Monk G. A. , 1982: A simple model for the synoptic analysis of cold fronts. Quart. J. Roy. Meteor. Soc., 108 , 435452.

  • Browning, K. A., , and Golding B. W. , 1995: Mesoscale aspects of a dry intrusion within a vigorous cyclone. Quart. J. Roy. Meteor. Soc., 121 , 463493.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Browning, K. A., , and Roberts N. M. , 1999: Mesoscale analysis of arc rainbands in a dry slot. Quart. J. Roy. Meteor. Soc., 125 , 34953511.

  • Carr, F. H., , and Millard J. P. , 1985: A composite study of comma clouds and their association with severe weather over the Great Plains. Mon. Wea. Rev., 113 , 370387.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Curtis, L., 2001: Mid-level dry intrusions as a factor in tornadogenesis associated with landfalling tropical cyclones in the central and western Gulf area. Preprints, 18th Conf. on Weather Analysis and Forecasting and 14th Conf. on Numerical Weather Prediction, Fort Lauderdale, FL, Amer. Meteor. Soc., 382–386.

    • Search Google Scholar
    • Export Citation
  • Dudhia, J., 1993: A nonhydrostatic version of the Penn State–NCAR Mesoscale Model: Validation tests and simulation of an Atlantic cyclone and cold front. Mon. Wea. Rev., 121 , 14931513.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Emanuel, K. A., 1994: Atmospheric Convection. Oxford University Press, 580 pp.

  • Fukuta, N., , and Takahashi T. , 1999: The growth of atmospheric ice crystals: A summary of findings in vertical supercooled cloud tunnel studies. J. Atmos. Sci., 56 , 19631979.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hill, E. L., , Malkin W. , , and Schulz W. A. , 1966: Tornadoes associated with cyclones of tropical origin—Practical features. J. Appl. Meteor., 5 , 745763.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hobbs, P. V., , Locatelli J. D. , , and Martin J. E. , 1990: Cold fronts aloft and the forecasting of precipitation and severe weather east of the Rocky Mountains. Wea Forecasting, 5 , 613626.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hobbs, P. V., , Locatelli J. D. , , and Martin J. E. , 1996: A new conceptual model for cyclones generated in the lee of the Rocky Mountains. Bull. Amer. Meteor. Soc., 77 , 11691178.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kuo, Y-H., , Reed R. J. , , and Low-Nam S. , 1992: Thermal structure and airflow in a model simulation of an occluded marine cyclone. Mon. Wea. Rev., 120 , 22802297.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Leese, J. A., 1962: The role of advection in the formation of vortex cloud patterns. Tellus, 14 , 409421.

  • Locatelli, J. D., , Martin J. E. , , Castle J. A. , , and Hobbs P. V. , 1995: Structure and evolution of winter cyclones in the central United States and their effects on the distribution of precipitation. Part III: The development of a squall line associated with weak cold frontogenesis aloft. Mon. Wea. Rev., 123 , 26412662.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Locatelli, J. D., , Schwartz R. D. , , Stoelinga M. T. , , and Hobbs P. V. , 2002: Norwegian-type and cold front aloft-type cyclones east of the Rocky Mountains. Wea. Forecasting, 17 , 6682.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lucas, C., , and Zipser E. J. , 2000: Environmental variability during TOGA COARE. J. Atmos. Sci., 57 , 23332350.

  • McCaul, E. W., 1987: Observations of the Hurricane “Danny” tornado outbreak of 16 August 1985. Mon. Wea. Rev., 115 , 12061223.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Parsons, D. B., , Yoneyama K. , , and Redelsperger J-L. , 2000: The evolution of the tropical western Pacific atmosphere–ocean system following the arrival of a dry intrusion. Quart. J. Roy. Meteor. Soc., 126 , 517548.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rodgers, E. B., , Olson W. S. , , Karyampudi V. M. , , and Pierce H. F. , 1998: Satellite-derived latent heating distribution and environmental influences in Hurricane Opal (1995). Mon. Wea. Rev., 126 , 12291247.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rodgers, E. B., , Olson W. S. , , Halverson J. B. , , Simpson J. , , and Pierce H. F. , 2000: Environmental forcing of Supertyphoon Paka's (1997) latent heat structure. J. Appl. Meteor., 39 , 19832006.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Salby, M. L., 1996: Fundamentals of Atmospheric Physics. Academic Press, 627 pp.

  • Soden, B. J., , and Fu R. , 1995: A satellite analysis of deep convection, upper-tropospheric humidity, and the greenhouse effect. J. Climate, 8 , 23332351.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vescio, M. D., , Weiss S. J. , , and Ostby F. P. , 1996: Tornadoes associated with Tropical Storm Beryl. Natl. Wea. Dig., 21 , 210.

  • Wei, D., , Blyth A. M. , , and Raymond D. J. , 1998: Buoyancy of convective clouds in TOGA COARE. J. Atmos. Sci., 55 , 33813391.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yoneyama, K., , and Parsons D. B. , 1999: A proposed mechanism for the intrusion of dry air into the tropical western Pacific region. J. Atmos. Sci., 56 , 15241546.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 91 91 5
PDF Downloads 15 15 5

The Diagnosis of Vertical Motion within Dry Intrusions

View More View Less
  • 1 Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania
© Get Permissions
Restricted access

Abstract

Dry intrusions play an important role in modulating precipitation patterns both in the midlatitudes and in the Tropics. The lifting of unsaturated air aloft often leads to destabilization and the enhancement of precipitation rates, and may occasionally contribute to the occurrence of severe weather. A method for qualitatively diagnosing vertical motion in a region of elevated dry advection is presented. The procedure measures the rate of propagation of relative humidity isopleths relative to the flow and deduces the sign of the vertical velocity. Changes in static stability are inferred, leading to the possibility of improved short-term forecasting of precipitation associated with dry intrusions.

The procedure is illustrated with a case study involving heavy snowfall associated with a dry intrusion in the mid-Atlantic region. A diagnosis of ascent within the dry intrusion is obtained from satellite imagery and confirmed using numerical model output.

Corresponding author address: Mr. Richard P. James, Dept. of Meteorology, The Pennsylvania State University, 503 Walker Building, University Park, PA 16802. Email: rpj105@psu.edu

Abstract

Dry intrusions play an important role in modulating precipitation patterns both in the midlatitudes and in the Tropics. The lifting of unsaturated air aloft often leads to destabilization and the enhancement of precipitation rates, and may occasionally contribute to the occurrence of severe weather. A method for qualitatively diagnosing vertical motion in a region of elevated dry advection is presented. The procedure measures the rate of propagation of relative humidity isopleths relative to the flow and deduces the sign of the vertical velocity. Changes in static stability are inferred, leading to the possibility of improved short-term forecasting of precipitation associated with dry intrusions.

The procedure is illustrated with a case study involving heavy snowfall associated with a dry intrusion in the mid-Atlantic region. A diagnosis of ascent within the dry intrusion is obtained from satellite imagery and confirmed using numerical model output.

Corresponding author address: Mr. Richard P. James, Dept. of Meteorology, The Pennsylvania State University, 503 Walker Building, University Park, PA 16802. Email: rpj105@psu.edu

Save