• Anderson, C. J., , and Arritt R. W. , 1998: Mesoscale convective complexes and persistent elongated convective systems over the United States during 1992 and 1993. Mon. Wea. Rev., 126 , 578599.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Anderson, C. J., , Gallus W. A. Jr., , Arritt R. W. , , and Kain J. S. , 2002: Impact of adjustments in the Kain–Fritsch convective scheme on QPF of elevated convection. Preprints, 19th Conf. on Weather Analysis and Forecasting, San Antonio, TX, Amer. Meteor. Soc., 23–24.

    • Search Google Scholar
    • Export Citation
  • Augustine, J. A., , and Caracena F. , 1994: Lower-tropospheric precursors to nocturnal MCS development over the central United States. Wea. Forecasting, 9 , 116135.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Barnes, S. L., 1973: Mesoscale objective map analysis using weighted time series observations. NOAA Tech. Memo. ERL NSSL 62, 60 pp. [NTIS COM-73-10781.].

    • Search Google Scholar
    • Export Citation
  • Bonner, W. D., 1968: Climatology of the low-level jet. Mon. Wea. Rev., 96 , 833850.

  • Borneman, R., , and Kadin C. , 1994: Catalogue of heavy rainfall cases of six inches or more over the continental U.S. during 1993. NOAA Tech. Rep. NESDIS 80, 154 pp.

    • Search Google Scholar
    • Export Citation
  • Colman, B. R., 1990a: Thunderstorms above frontal surfaces in environments without positive CAPE. Part I: A climatology. Mon. Wea. Rev., 118 , 11031121.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Colman, B. R., 1990b: Thunderstorms above frontal surfaces in environments without positive CAPE. Part II: Organization and instability mechanisms. Mon. Wea. Rev., 118 , 11231144.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cotton, W. R., , Lin M. S. , , McAnelly R. L. , , and Tremback C. J. , 1989: A composite model of mesoscale convective complexes. Mon. Wea. Rev., 117 , 765783.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Doswell, C. A., , and Rasmussen E. K. , 1994: The effect of neglecting the virtual temperature correction on CAPE calculations. Wea. Forecasting, 9 , 625629.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Doswell, C. A., , Brooks H. E. , , and Maddox R. A. , 1996: Flash flood forecasting: An ingredients-based methodology. Wea. Forecasting, 11 , 560581.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fritsch, J. M., , and Maddox R. A. , 1981: Convectively driven mesoscale weather systems aloft. Part I: Observations. J. Appl. Meteor., 20 , 919.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fritsch, J. M., , Kane R. J. , , and Chelius C. R. , 1986: The contribution of mesoscale convective weather systems to the warm season precipitation in the United States. J. Appl. Meteor., 25 , 13331345.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Glass, F. H., , Ferry D. L. , , Moore J. T. , , and Nolan S. M. , 1995: Characteristics of heavy convective rainfall events across the mid-Mississippi valley during the warm season: Meteorological conditions and a conceptual model. Preprints, 14th Conf. on Weather Forecasting and Analysis, Dallas, TX, Amer. Meteor. Soc., 34–41.

    • Search Google Scholar
    • Export Citation
  • Grant, B. N., 1995: Elevated cold-sector severe thunderstorms: A preliminary study. Natl. Wea. Dig., 19 (4) 2531.

  • Jankov, I., , and Gallus W. A. Jr., 2002: Contrast between good and bad forecasts of warm season MCSs in 10 km Eta simulations using two convective schemes. Preprints, 19th Conf. on Weather Analysis and Forecasting, San Antonio, TX, Amer. Meteor. Soc., 242–243.

    • Search Google Scholar
    • Export Citation
  • Junker, N. W., , Schneider R. S. , , and Scofield R. A. , 1995: The meteorological conditions associated with the great Midwest flood of 1993. Preprints, 14th Conf. on Weather Analysis and Forecasting, Dallas, TX, Amer. Meteor. Soc., (J4)13–(J4)17.

    • Search Google Scholar
    • Export Citation
  • Junker, N. W., , Schneider R. S. , , and Fauver S. L. , 1999: A study of heavy rainfall events during the great Midwest flood of 1993. Wea. Forecasting, 14 , 701712.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Juying, X., , and Scofield R. A. , 1989: Satellite-derived rainfall estimates and propagation characteristics associated with mesoscale convective systems (MCSs). NOAA Tech. Memo. NESDIS 25, 49 pp.

    • Search Google Scholar
    • Export Citation
  • Koch, S. E., , DesJardins M. , , and Kocin P. J. , 1983: An interactive Barnes objective map analysis scheme to use with satellite and conventional data. J. Climate Appl. Meteor., 22 , 14871503.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Maddox, R. A., 1980: Mesoscale convective complexes. Bull. Amer. Meteor. Soc., 61 , 13741387.

  • Maddox, R. A., 1983: Large-scale meteorological conditions associated with midlatitude, mesoscale convective complexes. Mon. Wea. Rev., 111 , 14751493.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Maddox, R. A., , and Doswell C. A. , 1982: An examination of jet stream configurations, 500 hPa vorticity advection, and low-level thermal advection patterns during extended periods of intense convection. Mon. Wea. Rev., 110 , 184197.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Maddox, R. A., , Chappell C. F. , , and Hoxit L. R. , 1979: Synoptic and meso-α scale aspects of flash flood events. Bull. Amer. Meteor. Soc., 60 , 115123.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McAnelly, R. L., , and Cotton W. R. , 1989: The precipitation life cycle of mesoscale convective complexes over the central United States. Mon. Wea. Rev., 117 , 784808.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McNulty, R. P., 1978: On upper tropospheric kinematics and severe weather occurrence. Mon. Wea. Rev., 106 , 662672.

  • Merritt, J. H., , and Fritsch J. M. , 1984: On the movement of heavy precipitation areas in mid-latitude mesoscale convective complexes. Preprints, 10th Conf. on Weather Analysis and Forecasting, Clearwater Beach, FL, Amer. Meteor. Soc., 529–536.

    • Search Google Scholar
    • Export Citation
  • Moore, J. T., , and VanKnowe G. E. , 1992: The effect of jet-streak curvature on kinematic fields. Mon. Wea. Rev., 120 , 24292441.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Moore, J. T., , Czarnetzki A. C. , , and Market P. S. , 1998: Heavy precipitation associated with elevated thunderstorms formed aloft in a convectively unstable layer. Meteor. Appl., 5 , 373384.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • NOAA, 1994: The Great Flood of 1993. Natural Disaster Survey Rep., NOAA, Rockville, MD, 317 pp.

  • Petterssen, S., 1956: Weather Analysis and Forecasting. Vol. 1. McGraw-Hill, 428 pp.

  • Rochette, S. M., , and Moore J. T. , 1996: Initiation of an elevated mesoscale convective system associated with heavy rainfall. Wea. Forecasting, 11 , 443457.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rochette, S. M., , Moore J. T. , , and Market P. S. , 1999: The importance of parcel choice in elevated CAPE computations. Natl. Wea. Dig., 23 (4) 2032.

    • Search Google Scholar
    • Export Citation
  • Shi, J., , and Scofield R. A. , 1987: Satellite observed mesoscale convective system (MCS) propagation characteristics and a 3–12 hour heavy precipitation forecast index. NOAA Tech. Memo. NESDIS 20, 43 pp.

    • Search Google Scholar
    • Export Citation
  • Snedecor, G. W., , and Cochran W. G. , 1967: Statistical Methods. 6th ed. The Iowa State University Press, 593 pp.

  • Williams, E., , and Renno N. , 1993: An analysis of the conditional instability of the tropical atmosphere. Mon. Wea. Rev., 121 , 2136.

    • Crossref
    • Search Google Scholar
    • Export Citation
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The Environment of Warm-Season Elevated Thunderstorms Associated with Heavy Rainfall over the Central United States

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  • 1 Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, Missouri
  • | 2 NOAA/National Weather Service Forecast Office, St. Charles, Missouri
  • | 3 Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, Missouri
  • | 4 State University of New York College at Brockport, Brockport, New York
  • | 5 Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, Missouri
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Abstract

Twenty-one warm-season heavy-rainfall events in the central United States produced by mesoscale convective systems (MCSs) that developed above and north of a surface boundary are examined to define the environmental conditions and physical processes associated with these phenomena. Storm-relative composites of numerous kinematic and thermodynamic fields are computed by centering on the heavy-rain-producing region of the parent elevated MCS. Results reveal that the heavy-rain region of elevated MCSs is located on average about 160 km north of a quasi-stationary frontal zone, in a region of low-level moisture convergence that is elongated westward on the cool side of the boundary. The MCS is located within the left-exit region of a south-southwesterly low-level jet (LLJ) and the right-entrance region of an upper-level jet positioned well north of the MCS site. The LLJ is directed toward a divergence maximum at 250 hPa that is coincident with the MCS site. Near-surface winds are light and from the southeast within a boundary layer that is statically stable and cool. Winds veer considerably with height (about 140°) from 850 to 250 hPa, a layer associated with warm-air advection. The MCS is located in a maximum of positive equivalent potential temperature θe advection, moisture convergence, and positive thermal advection at 850 hPa. Composite fields at 500 hPa show that the MCS forms in a region of weak anticyclonic curvature in the height field with marginal positive vorticity advection. Even though surface-based stability fields indicate stable low-level air, there is a layer of convectively unstable air with maximum-θe CAPE values of more than 1000 J kg−1 in the vicinity of the MCS site and higher values upstream. Maximum-θe convective inhibition (CIN) values over the MCS centroid site are small (less than 40 J kg−1) while to the south convection is limited by large values of CIN (greater than 60 J kg−1). Surface-to-500-hPa composite average relative humidity values are about 70%, and composite precipitable water values average about 3.18 cm (1.25 in.). The representativeness of the composite analysis is also examined. Last, a schematic conceptual model based upon the composite fields is presented that depicts the typical environment favorable for the development of elevated thunderstorms that lead to heavy rainfall.

Corresponding author address: James T. Moore, Dept. of Earth and Atmospheric Sciences, Saint Louis University, 3507 Laclede Ave., St. Louis, MO 63103. Email: moore@eas.slu.edu

Abstract

Twenty-one warm-season heavy-rainfall events in the central United States produced by mesoscale convective systems (MCSs) that developed above and north of a surface boundary are examined to define the environmental conditions and physical processes associated with these phenomena. Storm-relative composites of numerous kinematic and thermodynamic fields are computed by centering on the heavy-rain-producing region of the parent elevated MCS. Results reveal that the heavy-rain region of elevated MCSs is located on average about 160 km north of a quasi-stationary frontal zone, in a region of low-level moisture convergence that is elongated westward on the cool side of the boundary. The MCS is located within the left-exit region of a south-southwesterly low-level jet (LLJ) and the right-entrance region of an upper-level jet positioned well north of the MCS site. The LLJ is directed toward a divergence maximum at 250 hPa that is coincident with the MCS site. Near-surface winds are light and from the southeast within a boundary layer that is statically stable and cool. Winds veer considerably with height (about 140°) from 850 to 250 hPa, a layer associated with warm-air advection. The MCS is located in a maximum of positive equivalent potential temperature θe advection, moisture convergence, and positive thermal advection at 850 hPa. Composite fields at 500 hPa show that the MCS forms in a region of weak anticyclonic curvature in the height field with marginal positive vorticity advection. Even though surface-based stability fields indicate stable low-level air, there is a layer of convectively unstable air with maximum-θe CAPE values of more than 1000 J kg−1 in the vicinity of the MCS site and higher values upstream. Maximum-θe convective inhibition (CIN) values over the MCS centroid site are small (less than 40 J kg−1) while to the south convection is limited by large values of CIN (greater than 60 J kg−1). Surface-to-500-hPa composite average relative humidity values are about 70%, and composite precipitable water values average about 3.18 cm (1.25 in.). The representativeness of the composite analysis is also examined. Last, a schematic conceptual model based upon the composite fields is presented that depicts the typical environment favorable for the development of elevated thunderstorms that lead to heavy rainfall.

Corresponding author address: James T. Moore, Dept. of Earth and Atmospheric Sciences, Saint Louis University, 3507 Laclede Ave., St. Louis, MO 63103. Email: moore@eas.slu.edu

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