• Barcilon, A., , J. Jusem, , and P. Drazin, 1979: On the two-dimensional hydrostatic flow of a stream of moist air over a mountain ridge. Geophys. Astrophys. Fluid Dyn., 13 , 125140.

    • Search Google Scholar
    • Export Citation
  • Bell, G., , and L. Bosart, 1988: Appalachian cold-air damming. Mon. Wea. Rev., 116 , 137162.

  • Buzzi, A., , N. Tartaglione, , and P. Malguzzi, 1998: Numerical simulations of the 1994 Piedmont flood: Role of orography and moist processes. Mon. Wea. Rev., 126 , 23692383.

    • Search Google Scholar
    • Export Citation
  • Chen, W-D., , and R. Smith, 1987: Blocking and deflection of airflow by the Alps. Mon. Wea. Rev., 115 , 25782597.

  • De La Fuente, J., , and D. Elder, 1998: The flood of 1997 Klamath National Forest, phase I final report. U.S. Forest Service Tech. Rep., 76 pp.

  • Doyle, J., 1997: The influence of mesoscale orography on a coastal jet and rainband. Mon. Wea. Rev., 125 , 14651488.

  • Dudhia, J., 1989: Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model. J. Atmos. Sci., 46 , 30773107.

    • 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.

    • Search Google Scholar
    • Export Citation
  • Durran, D., , and J. Klemp, 1982: On the effects of moisture on the Brunt–Väisälä frequency. J. Atmos. Sci., 39 , 21522158.

  • Ferretti, R., , S. Low-Nam, , and R. Rotunno, 2000: Numerical simulations of the Piedmont flood of 4–6 November 1994. Tellus, 52A , 162180.

    • Search Google Scholar
    • Export Citation
  • Groisman, P., , and D. Legates, 1994: The accuracy of United States precipitation data. Bull. Amer. Meteor. Soc., 75 , 215227.

  • Higgins, R., , J-K. Schemm, , W. Shi, , and A. Leetma, 2000: Extreme precipitation events in the western United States related to tropical forcing. J. Climate, 13 , 793820.

    • Search Google Scholar
    • Export Citation
  • Hong, S-Y., , and H-L. Pan, 1996: Nonlocal boundary layer vertical diffusion in a medium-range forecast model. Mon. Wea. Rev., 124 , 23222339.

    • Search Google Scholar
    • Export Citation
  • Hunrichs, R., , D. Pratt, , and R. Meyer, 1998: Magnitude and frequency of the floods of January 1997 in northern and central California—Preliminary determinations. U.S. Geological Survey Open File Rep. 98–626, 120 pp.

  • Jiang, Q., 2003: Moist dynamics and orographic precipitation. Tellus, 55A , 301316.

  • Jones, C., 2000: Occurrence of extreme precipitation events in California and relationships with the Madden–Julian oscillation. J. Climate, 13 , 35763587.

    • Search Google Scholar
    • Export Citation
  • Kain, J., , and J. Fritsch, 1993: Convective parameterization for mesoscale models: The Kain–Fritsch scheme. The Representation of Cumulus Convection in Numerical Models, Meteor. Monogr., No. 46, Amer. Meteor. Soc., 246 pp.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Lackmann, G., 2002: Cold-frontal potential vorticity maxima, the low-level jet, and moisture transport in extratropical cyclones. Mon. Wea. Rev., 130 , 5974.

    • Search Google Scholar
    • Export Citation
  • Lackmann, G., , and J. Gyakum, 1999: Heavy cold-season precipitation in the northwestern United States: Synoptic climatology and an analysis of the flood of 17–18 January 1986. Wea. Forecasting, 14 , 687700.

    • Search Google Scholar
    • Export Citation
  • Leung, L., , Y. Qian, , X. Bian, , and A. Hunt, 2003: Hydroclimate of the western United States based on observations and regional climate simulation of 1981–2000. Part II: Mesoscale ENSO anomalies. J. Climate, 16 , 19121928.

    • Search Google Scholar
    • Export Citation
  • Lott, N., , D. Ross, , and M. Sittel, 1997: The winter of ’96–’97 West Coast flooding. National Climatic Data Center, Tech. Rep. 97-01, 22 pp.

  • Mass, C., , D. Ovens, , and K. Westrick, 2002: Does increasing horizontal resolution produce more skillful forecasts? Bull. Amer. Meteor. Soc., 83 , 407430.

    • Search Google Scholar
    • Export Citation
  • Mo, K., , and R. Higgins, 1998a: Tropical convection and precipitation regimes in the western United States. J. Climate, 11 , 24042423.

  • Mo, K., , and R. Higgins, 1998b: Tropical influences on California precipitation. J. Climate, 11 , 412430.

  • Ogston, A., , D. Cacchione, , R. Sternberg, , and G. Kineje, 2000: Observations of storm and river flood-driven sediment transport on the northern California continental shelf. Cont. Shelf Res., 20 , 21412162.

    • Search Google Scholar
    • Export Citation
  • Overland, J., , and N. Bond, 1993: The influence of coastal orography: The Yakutat storm. Mon. Wea. Rev., 121 , 13881397.

  • Overland, J., , and N. Bond, 1995: Observations and scale analysis of coastal wind jets. Mon. Wea. Rev., 123 , 29342941.

  • Pandey, G., , D. Cayan, , and K. Georgakakos, 1999: Precipitation structure in the Sierra Nevada of California. J. Geophys. Res., 104 , D10,. 1201912030.

    • Search Google Scholar
    • Export Citation
  • Parish, T., 1982: Barrier winds along the Sierra Nevada Mountains. J. Appl. Meteor., 21 , 925930.

  • Pierrehumbert, R., 1984: Linear results on the barrier effects of mesoscale mountains. J. Atmos. Sci., 41 , 13561367.

  • Pierrehumbert, R., , and B. Wyman, 1985: Upstream effects of mesoscale mountains. J. Atmos. Sci., 42 , 9771003.

  • Ralph, F. M., , P. J. Neiman, , D. E. Kingsmill, , P. O. G. Persson, , A. B. White, , E. T. Strem, , E. D. Andrews, , and R. C. Antweiler, 2003: The impact of a prominent rain shadow on flooding in California’s Santa Cruz Mountains: A CALJET case study and sensitivity to the ENSO cycle. J. Hydrometeor., 4 , 12431264.

    • Search Google Scholar
    • Export Citation
  • Rotunno, R., , and R. Ferretti, 2001: Mechanisms of intense Alpine rainfall. J. Atmos. Sci., 58 , 17321749.

  • Smith, R., 1979: The influence of mountains on the atmosphere. Advances in Geophysics, Vol. 21, Academic Press, 87–230.

  • Smolarkiewicz, P., , and R. Rotunno, 1989: Low Froude number flow past three-dimensional obstacles. Part I: Baroclinically generated lee vortices. J. Atmos. Sci., 46 , 11541164.

    • Search Google Scholar
    • Export Citation
  • Smolarkiewicz, P., , and R. Rotunno, 1990: Low Froude number flow past three-dimensional obstacles. Part II: Upwind flow reversal zone. J. Atmos. Sci., 47 , 14981511.

    • Search Google Scholar
    • Export Citation
  • Steenburgh, W., , and C. Mass, 1996: Interaction of an intense extratropical cyclone with coastal orography. Mon. Wea. Rev., 124 , 13291352.

    • Search Google Scholar
    • Export Citation
  • Xiu, Q., 1990: A theoretical study of cold air damming. J. Atmos. Sci., 47 , 29692985.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 72 72 16
PDF Downloads 2500 2500 12

Moist Dynamics and Orographic Precipitation in Northern and Central California during the New Year’s Flood of 1997

View More View Less
  • 1 Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York
© Get Permissions
Restricted access

Abstract

The dynamics of moist orographic flows during the January 1997 floods in northern and central California are investigated using numerical simulations computed with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5). Early in the event (31 December 1996–1 January 1997), the low-level winds offshore of California’s central coast were blocked by the topography of the Santa Lucia Range, and the low-level winds in the Central Valley were blocked by the topography of the central Sierra Nevada Range. In contrast, moisture-laden winds along the northern Coast Ranges and the northern Sierra Nevada flowed over topographic barriers. As the core of humid air migrated to the south over 24 h, the low-level barrier jets weakened as the atmospheric stability decreased, bringing heavy rainfall to the central and southern Sierra Nevada at the end of the event. The heavy precipitation during this event was largely controlled by the interaction of the flow with topography, with little contribution from non–topographically forced dynamical uplift. Latent heating was essential for lowering the effective stability of the flow and allowing the winds to flow over mountainous terrain, particularly in the northern Coast Ranges, and for enhancing the low-level jet and associated moisture transport. The horizontal distribution of static stability played a key role in the event by setting up a complex combination of flow-over and flow-around regimes that enhanced uplift in the northern Sierra Nevada during the period of heaviest rainfall.

Corresponding author address: Joseph Galewsky, Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027. Email: jg2282@columbia.edu

Abstract

The dynamics of moist orographic flows during the January 1997 floods in northern and central California are investigated using numerical simulations computed with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5). Early in the event (31 December 1996–1 January 1997), the low-level winds offshore of California’s central coast were blocked by the topography of the Santa Lucia Range, and the low-level winds in the Central Valley were blocked by the topography of the central Sierra Nevada Range. In contrast, moisture-laden winds along the northern Coast Ranges and the northern Sierra Nevada flowed over topographic barriers. As the core of humid air migrated to the south over 24 h, the low-level barrier jets weakened as the atmospheric stability decreased, bringing heavy rainfall to the central and southern Sierra Nevada at the end of the event. The heavy precipitation during this event was largely controlled by the interaction of the flow with topography, with little contribution from non–topographically forced dynamical uplift. Latent heating was essential for lowering the effective stability of the flow and allowing the winds to flow over mountainous terrain, particularly in the northern Coast Ranges, and for enhancing the low-level jet and associated moisture transport. The horizontal distribution of static stability played a key role in the event by setting up a complex combination of flow-over and flow-around regimes that enhanced uplift in the northern Sierra Nevada during the period of heaviest rainfall.

Corresponding author address: Joseph Galewsky, Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027. Email: jg2282@columbia.edu

Save