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Article Type:
Research Article

Cold-Frontal Potential Vorticity Maxima, the Low-Level Jet, and Moisture Transport in Extratropical Cyclones

Gary M. Lackmann Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina

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Print Publication:
01 Jan 2002
DOI:
https://doi.org/10.1175/1520-0493(2002)130<0059:CFPVMT>2.0.CO;2
Page(s):
59ā€“74
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Abstract

An elongated cold-frontal maximum in the lower-tropospheric potential vorticity (PV) field accompanies some midlatitude cyclones. These PV maxima are often of diabatic origin, and are hypothesized to contribute substantially to the strength of the low-level jet (LLJ) and moisture transport in the cyclone warm sector. Diagnosis of a representative cyclone event from the central United States during February 1997 is presented with the goals of (i) elucidating the mechanisms of development and propagation of the cold-frontal PV band, and (ii) clarifying the relation between this PV maximum and the LLJ.

A confluent upper trough and modest surface cyclone followed a track from the south-central United States northeastward into southern Ontario between 26 and 28 February 1997, accompanied by flooding and widespread straight-line wind damage. A LLJ, with maximum wind speeds in excess of 35 m sāˆ’1, was positioned at the western extremity of the cyclone warm sector, immediately east of an elongated PV maximum in the lower troposphere. Results of an Ertel PV budget confirm the importance of latent heat release to the development and eastward propagation of the PV band. Cancellation was observed between the vertical PV advection, which yielded negative (positive) tendencies beneath (above) the cold-frontal PV maximum, and the nonadvective PV tendency, which was positive (negative) beneath (above) the level of maximum heating. The nonadvective PV flux is directed opposite the absolute vorticity vector; therefore vertical wind shear (associated with westward-tilting absolute vorticity vectors) led to eastward nonadvective propagation of the PV maximum. Quasigeostrophic PV inversion indicates that the cold-frontal PV maximum contributed between 15% and 40% to the strength of the LLJ within the cyclone warm sector. The results of this study suggest that a complex interdependence can exist between cold-frontal rainbands, lower-tropospheric PV maxima, the LLJ, and warm-sector moisture transport. The implications of this linkage for numerical weather forecasting are discussed.

Corresponding author address: Gary M. Lackmann, Department of Marine, Earth, and Atmospheric Sciences, 1125 Jordan Hall, North Carolina State University, Raleigh, NC 27695-8208. Email: gary@ncsu.edu

Abstract

An elongated cold-frontal maximum in the lower-tropospheric potential vorticity (PV) field accompanies some midlatitude cyclones. These PV maxima are often of diabatic origin, and are hypothesized to contribute substantially to the strength of the low-level jet (LLJ) and moisture transport in the cyclone warm sector. Diagnosis of a representative cyclone event from the central United States during February 1997 is presented with the goals of (i) elucidating the mechanisms of development and propagation of the cold-frontal PV band, and (ii) clarifying the relation between this PV maximum and the LLJ.

A confluent upper trough and modest surface cyclone followed a track from the south-central United States northeastward into southern Ontario between 26 and 28 February 1997, accompanied by flooding and widespread straight-line wind damage. A LLJ, with maximum wind speeds in excess of 35 m sāˆ’1, was positioned at the western extremity of the cyclone warm sector, immediately east of an elongated PV maximum in the lower troposphere. Results of an Ertel PV budget confirm the importance of latent heat release to the development and eastward propagation of the PV band. Cancellation was observed between the vertical PV advection, which yielded negative (positive) tendencies beneath (above) the cold-frontal PV maximum, and the nonadvective PV tendency, which was positive (negative) beneath (above) the level of maximum heating. The nonadvective PV flux is directed opposite the absolute vorticity vector; therefore vertical wind shear (associated with westward-tilting absolute vorticity vectors) led to eastward nonadvective propagation of the PV maximum. Quasigeostrophic PV inversion indicates that the cold-frontal PV maximum contributed between 15% and 40% to the strength of the LLJ within the cyclone warm sector. The results of this study suggest that a complex interdependence can exist between cold-frontal rainbands, lower-tropospheric PV maxima, the LLJ, and warm-sector moisture transport. The implications of this linkage for numerical weather forecasting are discussed.

Corresponding author address: Gary M. Lackmann, Department of Marine, Earth, and Atmospheric Sciences, 1125 Jordan Hall, North Carolina State University, Raleigh, NC 27695-8208. Email: gary@ncsu.edu

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  • Aebischer, U., and C. SchƤr, 1998: Low-level potential vorticity and cyclogenesis to the lee of the Alps. J. Atmos. Sci, 55 , 186ā€“207.

    • Search Google Scholar
    • Export Citation

  • Anthes, R. A., Y-H. Kuo, and J. R. Gyakum, 1983: Numerical simulations of a case of explosive marine cyclogenesis. Mon. Wea. Rev, 111 , 1174ā€“1188.

    • Search Google Scholar
    • Export Citation

  • Arakawa, A., 1994: Closure assumptions in the cumulus parameterization problem. The Representation of Cumulus Convection in Numerical Models, Meteor. Monogr., No. 46, Amer. Meteor. Soc., 1ā€“16.

    • Search Google Scholar
    • Export Citation

  • Braun, S. A., and R. A. Houze Jr., 1996: The heat budget of a midlatitude squall line and implications for potential vorticity production. J. Atmos. Sci, 53 , 1217ā€“1240.

    • Search Google Scholar
    • Export Citation

  • Browning, K. A., and T. W. Harrold, 1970: Air motion and precipitation growth at a cold front. Quart. J. Roy. Meteor. Soc, 96 , 369ā€“389.

    • Search Google Scholar
    • Export Citation

  • Browning, K. A., and C. W. Pardoe, 1973: Structure of low-level jet streams ahead of mid-latitude cold fronts. Quart. J. Roy. Meteor. Soc, 99 , 619ā€“638.

    • Search Google Scholar
    • Export Citation

  • Browning, K. A., and R. Reynolds, 1994: Diagnostic study of a narrow cold-frontal rainband and severe winds associated with a stratospheric intrusion. Quart. J. Roy. Meteor. Soc, 120 , 235ā€“257.

    • Search Google Scholar
    • Export Citation

  • Cammas, J-P., D. Keyser, G. M. Lackmann, and J. Molinari, 1994: Diabatic redistribution of potential vorticity accompanying the development of an outflow jet within a strong extratropical cyclone. Proc. Int. Symp. on the Life Cycles of Extratropical Cyclones, Vol. II. Bergen, Norway, Geophysical Institute, University of Bergen. 403ā€“409.

    • Search Google Scholar
    • Export Citation

  • Chen, T-C., and J. A. Kpaeyeh, 1993: The synoptic-scale environment associated with the low-level jet of the Great Plains. Mon. Wea. Rev, 121 , 416ā€“420.

    • Search Google Scholar
    • Export Citation

  • Davis, C. A., 1992a: A potential-vorticity diagnosis of the importance of initial structure and condensational heating in observed extratropical cyclogenesis. Mon. Wea. Rev, 120 , 2409ā€“2428.

    • Search Google Scholar
    • Export Citation

  • Davis, C. A., 1992b: Piecewise potential vorticity inversion. J. Atmos. Sci, 49 , 1397ā€“1411.

  • Davis, C. A., and K. A. Emanuel, 1991: Potential vorticity diagnostics of cyclogenesis. Mon. Wea. Rev, 119 , 1929ā€“1953.

  • Davis, C. A., M. T. Stoelinga, and Y-H. Kuo, 1993: The integrated effect of condensation in numerical simulations of extratropical cyclogenesis. Mon. Wea. Rev, 121 , 2309ā€“2330.

    • Search Google Scholar
    • Export Citation

  • Emanuel, K. A., M. Fantini, and A. J. Thorpe, 1987: Baroclinic instability in an environment of small stability to slantwise moist convection. Part I: Two-dimensional models. J. Atmos. Sci, 44 , 1559ā€“1573.

    • Search Google Scholar
    • Export Citation

  • Emanuel, K. A., and and Coauthors, 1995: Report of the first prospectus development team of the U.S. Weather Research Program to NOAA and the NSF. Bull. Amer. Meteor. Soc, 76 , 1194ā€“1208.

    • Search Google Scholar
    • Export Citation

  • Fritsch, J. M., and and Coauthors, 1998: Quantitative precipitation forecasting: Report of the eighth prospectus development team, U. S. Weather Research Program. Bull. Amer. Meteor. Soc, 79 , 285ā€“299.

    • Search Google Scholar
    • Export Citation

  • Gallus, W. A., 1999: Eta simulations of three extreme precipitation events: Impact of resolution and choice of convective parameterization. Wea. Forecasting, 14 , 405ā€“426.

    • Search Google Scholar
    • Export Citation

  • Gyakum, J. R., 1983a: On the evolution of the QE II storm. I: Synoptic aspects. Mon. Wea. Rev, 111 , 1137ā€“1155.

  • Gyakum, J. R., 1983b: On the evolution of the QE II storm. II: Dynamic and thermodynamic structure. Mon. Wea. Rev, 111 , 1156ā€“1173.

  • Hakim, G. J., D. Keyser, and L. F. Bosart, 1996: The Ohio Valley wave-merger cyclogenesis event of 25ā€“26 January 1978. Part II: Diagnosis using quasigeostrophic potential vorticity inversion. Mon. Wea. Rev, 124 , 2176ā€“2205.

    • Search Google Scholar
    • Export Citation

  • Haynes, P. H., and M. E. McIntyre, 1987: On the evolution of vorticity and potential vorticity in the presence of diabatic heating and frictional or other forces. J. Atmos. Sci, 44 , 828ā€“840.

    • Search Google Scholar
    • Export Citation

  • Hertenstein, R. F. A., and W. H. Schubert, 1991: Potential vorticity anomalies associated with squall lines. Mon. Wea. Rev, 119 , 1663ā€“1672.

    • Search Google Scholar
    • Export Citation

  • Hoskins, B. J., M. E. McIntyre, and A. W. Robertson, 1985: On the use and significance of isentropic potential vorticity maps. Quart. J. Roy. Meteor. Soc, 111 , 877ā€“946.

    • Search Google Scholar
    • Export Citation

  • Joly, A., and A. J. Thorpe, 1990: Frontal instability generated by tropospheric potential vorticity anomalies. Quart. J. Roy. Meteor. Soc, 116 , 525ā€“560.

    • Search Google Scholar
    • Export Citation

  • Kotroni, V., Y. Lemaitre, and M. Petitdidier, 1994: Dynamics of a low-level jet observed during the FRONTS 87 experiment. Quart. J. Roy. Meteor. Soc, 120 , 277ā€“303.

    • Search Google Scholar
    • Export Citation

  • Kuo, Y-H., and S. Low-Nam, 1990: Prediction of nine explosive cyclones over the western Atlantic Ocean with a regional model. Mon. Wea. Rev, 118 , 3ā€“25.

    • Search Google Scholar
    • Export Citation

  • Kutzbach, G., 1979: The Thermal Theory of Cyclones: A History of Meteorological Thought in the Nineteenth Century. Amer. Meteor. Soc., 255 pp.

    • Search Google Scholar
    • Export Citation

  • Lackmann, G. M., and J. R. Gyakum, 1999: Heavy cold-season precipitation in the northwestern United States: Synoptic climatology and an analysis of the flood of 17ā€“18 January 1986. Wea. Forecasting, 14 , 687ā€“700.

    • Search Google Scholar
    • Export Citation

  • Lackmann, G. M., J. R. Gyakum, and R. Benoit, 1998: Moisture transport diagnosis of a wintertime precipitation event in the Mackenzie River basin. Mon. Wea. Rev, 126 , 668ā€“691.

    • Search Google Scholar
    • Export Citation

  • Malardel, S., A. Joly, F. Courbet, and Ph Courtier, 1993: Nonlinear evolution of ordinary frontal waves induced by low-level potential vorticity anomalies. Quart. J. Roy. Meteor. Soc, 119 , 681ā€“713.

    • Search Google Scholar
    • Export Citation

  • Massacand, A. C., H. Wernli, and H. C. Davies, 2001: Influence of upstream diabatic heating upon an Alpine event of heavy precipitation. Mon. Wea. Rev.,. 129 , 2822ā€“2828.

    • Search Google Scholar
    • Export Citation

  • Mitchell, M. J., R. W. Aritt, and K. Labas, 1995: A climatology of the warm season Great Plains low level jet using wind profiler observations. Wea. Forecasting, 10 , 576ā€“591.

    • Search Google Scholar
    • Export Citation

  • Molinari, J., and M. Dudek, 1992: Parameterization of convective precipitation in mesoscale numerical models: A critical review. Mon. Wea. Rev, 120 , 326ā€“344.

    • Search Google Scholar
    • Export Citation

  • NCDC, 1997: Storm Data. Vol. 39, No. 2, 148 pp. [Available from National Climatic Data Center, Rm. 120, 151 Patton Ave., Asheville, NC 28801-5001.].

    • Search Google Scholar
    • Export Citation

  • Olson, D. A., N. W. Junker, and B. Korty, 1995: Evaluation of 33 years of quantitative precipitation forecasting at the NMC. Wea. Forecasting, 10 , 498ā€“511.

    • Search Google Scholar
    • Export Citation

  • Persson, P. O. G., 1995: Simulations of the potential vorticity structure and budget of FRONTS 87 IOP 8. Quart. J. Roy. Meteor. Soc, 121 , 1041ā€“1081.

    • Search Google Scholar
    • Export Citation

  • Petterssen, S., 1956: Weather Analysis and Forecasting, 2d ed. McGraw-Hill, 428 pp.

  • Raymond, D. J., 1992: Nonlinear balance and potential-vorticity thinking at large Rossby number. Quart. J. Roy. Meteor. Soc, 118 , 987ā€“1015.

    • Search Google Scholar
    • Export Citation

  • Reed, R. J., and Y-H. Kuo, 1988: Numerical simulation of an explosively deepening cyclone in the eastern Pacific. Mon. Wea. Rev, 116 , 2081ā€“2105.

    • Search Google Scholar
    • Export Citation

  • Reed, R. J., M. T. Stoelinga, and Y-H. Kuo, 1992: A model-aided study of the origin and evolution of the anomalously high potential vorticity in the inner region of a rapidly deepening marine cyclone. Mon. Wea. Rev, 120 , 893ā€“913.

    • Search Google Scholar
    • Export Citation

  • Reed, R. J., A. J. Simmons, M. D. Albright, and P. UndĆ©n, 1988: The role of latent heat release in explosive cyclogenesis: Three examples based on ECMWF operational forecasts. Wea. Forecasting, 3 , 217ā€“229.

    • Search Google Scholar
    • Export Citation

  • Rogers, E., D. G. Deaven, and G. J. DiMego, 1995: The regional analysis system for the operational ā€œearlyā€ eta model: Original 80 km configuration and recent changes. Wea. Forecasting, 10 , 810ā€“825.

    • Search Google Scholar
    • Export Citation

  • Rogers, E., and and Coauthors, 1996: Changes to the operational ā€œearlyā€ eta analysis/forecast system at the National Centers for Environmental Prediction. Wea. Forecasting, 11 , 391ā€“413.

    • Search Google Scholar
    • Export Citation

  • Rossa, A. M., H. Wernli, and H. C. Davies, 2000: Growth and decay of an extra-tropical cyclone's PV-tower. Meteor. Atmos. Phys, 73 , 139ā€“156.

    • Search Google Scholar
    • Export Citation

  • Spencer, P. L., and D. J. Stensrud, 1998: Simulating flash flood events: Importance of the subgrid representation of convection. Mon. Wea. Rev, 126 , 2884ā€“2912.

    • Search Google Scholar
    • Export Citation

  • Stensrud, D. J., J-W. Bao, and T. T. Warner, 2000: Using initial condition and model physics perturbations in short-range ensemble simulations of mesoscale convective systems. Mon. Wea. Rev, 128 , 2077ā€“2107.

    • Search Google Scholar
    • Export Citation

  • Stoelinga, M. T., 1996: A potential vorticity-based study of the role of diabatic heating and friction in a numerically simulated baroclinic cyclone. Mon. Wea. Rev, 124 , 849ā€“874.

    • Search Google Scholar
    • Export Citation

  • Sutcliffe, R. C., and A. G. Forsdyke, 1950: The theory and use of upper air thickness patterns in forecasting. Quart. J. Roy. Meteor. Soc, 76 , 189ā€“217.

    • Search Google Scholar
    • Export Citation

  • Thorpe, A. J., H. Volkert, and D. Heimann, 1993: Potential vorticity of flow along the Alps. J. Atmos. Sci, 50 , 1573ā€“1590.

  • Tracton, M. S., 1973: The role of cumulus convection in the development of extratropical cyclones. Mon. Wea. Rev, 101 , 573ā€“592.

  • Uccellini, L. W., 1980: On the role of upper tropospheric jet streaks and leeside cyclogenesis in the development of low-level jets in the Great Plains. Mon. Wea. Rev, 108 , 1689ā€“1696.

    • Search Google Scholar
    • Export Citation

  • Uccellini, L. W., 1990: Processes contributing to the rapid development of extratropical cyclones. Extratropical Cyclonesā€”The Erik PalmĆ©n Memorial Volume, C. W. Newton and E. O. Holopainen, Eds., Amer. Meteor. Soc., 81ā€“105.

    • Search Google Scholar
    • Export Citation

  • Wang, W., and N. L. Seaman, 1997: A comparison study of convective parameterization schemes in a mesoscale model. Mon. Wea. Rev, 125 , 252ā€“278.

    • Search Google Scholar
    • Export Citation
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