• Bader, M. J., G. S. Forbes, J. R. Grant, R. B. E. Lilly, and A. J. Waters, 1995: Images in Weather Forecasting. Cambridge University Press, 499 pp.

    • Search Google Scholar
    • Export Citation
  • Bjerknes, J., and H. Solberg, 1922: Life cycle of cyclones and the polar front theory of atmospheric circulation. Geofys. Publ., 3 , 118.

    • Search Google Scholar
    • Export Citation
  • Bosart, L. F., 1981: The Presidents’ Day snowstorm of 18–19 February 1979: A subsynoptic-scale event. Mon. Wea. Rev., 109 , 15421566.

    • Search Google Scholar
    • Export Citation
  • Browning, K. A., 1971: Radar measurements of air motion near fronts. Weather, 26 , 320340.

  • Browning, K. A., 1986: Conceptual models of precipitation systems. Wea. Forecasting, 1 , 2341.

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

    • Search Google Scholar
    • Export Citation
  • Browning, K. A., and F. F. Hill, 1985: Mesoscale analysis of a polar trough intersecting with a polar front. Quart. J. Roy. Meteor. Soc., 111 , 445462.

    • Search Google Scholar
    • Export Citation
  • Browning, K. A., and N. M. Roberts, 1994: Structure of a frontal cyclone. Quart. J. Roy. Meteor. Soc., 120 , 15351557.

  • Browning, K. A., and N. M. Roberts, 1996: Variation of frontal and precipitation structure along a cold front. Quart. J. Roy. Meteor. Soc., 122 , 18451872.

    • Search Google Scholar
    • Export Citation
  • Browning, K. A., S. P. Ballard, and C. S. A. Davitt, 1997: High-resolution analysis of frontal fracture. Mon. Wea. Rev., 125 , 12121230.

    • Search Google Scholar
    • Export Citation
  • Carlson, T. N., 1980: Airflow through midlatitude cyclones and the comma cloud pattern. Mon. Wea. Rev., 108 , 14981509.

  • Carlson, T. N., 1991: Mid-Latitude Weather Systems. Harper Collins Academic, 507 pp.

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

    • Search Google Scholar
    • Export Citation
  • Cressman, G. P., 1959: An operational objective analysis scheme. Mon. Wea. Rev., 87 , 367374.

  • Crocker, A. M., W. L. Godson, and C. M. Penner, 1947: Frontal contour charts. J. Meteor., 4 , 9599.

  • desJardins, M., K. Brill, and S. Schots, 1991: Use of GEMPAK on Unix workstations. Preprints, Seventh Int. Conf. on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, New Orleans, LA, Amer. Meteor. Soc., 449–451.

  • Draxler, R. R., and G. D. Hess, 1998: An overview of the HYSPLIT4 modeling system for trajectories, dispersion, and deposition. Aust. Meteor. Mag., 47 , 295308.

    • Search Google Scholar
    • Export Citation
  • Galloway, J. L., 1958: The three-front model: It’s philosophy, nature, construction and use. Weather, 13 , 293301.

  • Galloway, J. L., 1960: The three-front model, the developing depression and the occluding process. Weather, 15 , 293301.

  • Godson, W. L., 1951: Synoptic properties of frontal surfaces. Quart. J. Roy. Meteor. Soc., 77 , 633653.

  • Gyakum, J. R., and P. J. Roebber, 2001: The 1998 ice storm—Analysis of a planetary-scale event. Mon. Wea. Rev., 129 , 29832997.

  • Halcomb, C. E., and P. S. Market, 2003: Forcing, instability, and equivalent potential vorticity in a midwestern U.S. convective snowstorm. Meteor. Appl., 10 , 273280.

    • Search Google Scholar
    • Export Citation
  • Han, M., R. M. Rauber, M. K. Ramamurthy, B. F. Jewett, and J. A. Grim, 2007: Mesoscale dynamics of the trowal and warm-frontal regions of two continental winter cyclones. Mon. Wea. Rev., 135 , 16471670.

    • Search Google Scholar
    • Export Citation
  • Harrold, T. W., 1973: Mechanisms influencing the distribution of precipitation within baroclinic disturbances. Quart. J. Roy. Meteor. Soc., 99 , 232251.

    • Search Google Scholar
    • Export Citation
  • Hildebrand, P. H., and Coauthors, 1996: The ELDORA/ASTRAIA airborne Doppler weather radar: High-resolution observations from TOGA COARE. Bull. Amer. Meteor. Soc., 77 , 213232.

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

    • Search Google Scholar
    • Export Citation
  • Hock, T. F., and J. L. Franklin, 1999: The NCAR GPS Dropwindsonde. Bull. Amer. Meteor. Soc., 80 , 407420.

  • Kreitzberg, C. W., 1968: The mesoscale wind field in an occlusion. J. Appl. Meteor., 7 , 5367.

  • Kristovich, D. A. R., and Coauthors, 2000: The lake-induced convection experiment and the snowband dynamics project. Bull. Amer. Meteor. Soc., 81 , 519542.

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

    • Search Google Scholar
    • Export Citation
  • Locatelli, J. D., J. E. Martin, J. A. Castle, and P. V. Hobbs, 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.

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

    • Search Google Scholar
    • Export Citation
  • Market, P. S., and D. Cissell, 2002: Formation of a sharp snow gradient in a Midwestern heavy snow event. Wea. Forecasting, 17 , 723738.

    • Search Google Scholar
    • Export Citation
  • Martin, J. E., 1998a: The structure and evolution of a continental winter cyclone. Part I: Frontal structure and the occlusion process. Mon. Wea. Rev., 126 , 303328.

    • Search Google Scholar
    • Export Citation
  • Martin, J. E., 1998b: The structure and evolution of a continental winter cyclone. Part II: Frontal forcing of an extreme snow event. Mon. Wea. Rev., 126 , 329348.

    • Search Google Scholar
    • Export Citation
  • Martin, J. E., 1999: Quasigeostrophic forcing of ascent in the occluded sector of cyclones and the trowal airstream. Mon. Wea. Rev., 127 , 7088.

    • Search Google Scholar
    • Export Citation
  • Mass, C. F., and D. M. Schultz, 1993: The structure and evolution of a simulated midlatitude cyclone over land. Mon. Wea. Rev., 121 , 889917.

    • Search Google Scholar
    • Export Citation
  • Mohr, C. G., L. J. Miller, R. L. Vaughn, and H. W. Frank, 1986: Merger of mesoscale dataset into a common Cartesian format for efficient and systematic analysis. J. Atmos. Oceanic Technol., 3 , 143161.

    • Search Google Scholar
    • Export Citation
  • Mook, C. P., and K. S. Norquest, 1956: The heavy snowstorm of March 18–19, 1956. Mon. Wea. Rev., 84 , 116125.

  • Moore, J. T., C. E. Graves, S. Ng, and J. L. Smith, 2005: A process-oriented methodology toward understanding the organization of an extensive mesoscale snowband: A diagnostic case study of 4–5 December 1999. Wea. Forecasting, 20 , 3550.

    • Search Google Scholar
    • Export Citation
  • Neiman, P. J., F. M. Ralph, M. A. Shapiro, B. F. Smull, and D. Johnson, 1998: An observational study of fronts and frontal mergers over the continental United States. Mon. Wea. Rev., 126 , 25212554.

    • Search Google Scholar
    • Export Citation
  • Novak, D. R., L. F. Bosart, D. Keyser, and J. S. Waldstreicher, 2004: An observational study of cold season-banded precipitation in northeast U.S. cyclones. Wea. Forecasting, 19 , 9931010.

    • Search Google Scholar
    • Export Citation
  • NSSL, 2000: WATADS (WSR-88D Algorithm Testing and Display System) 2000: Reference guide for version 10.2. NSSL, 200 pp. [Available from Storm Scale Applications Division, National Severe Storms Laboratory, 1313 Halley Circle, Norman, OK 73069.].

  • Parmenter, F. C., 1970: Pacific cyclones viewed by ATS I. Mon. Wea. Rev., 98 , 8384.

  • Penner, C. M., 1955: A three-front model for synoptic analyses. Quart. J. Roy. Meteor. Soc., 81 , 8991.

  • Posselt, D. J., and J. E. Martin, 2004: The effect of latent heat release on the evolution of a warm occluded thermal structure. Mon. Wea. Rev., 132 , 578599.

    • Search Google Scholar
    • Export Citation
  • Reed, R. J., Y-H. Kuo, and S. Low-Nam, 1994: An adiabatic simulation of the ERICA IOP 4 storm: An example of quasi-ideal frontal cyclone development. Mon. Wea. Rev., 122 , 26882708.

    • Search Google Scholar
    • Export Citation
  • Roebber, P. J., and J. R. Gyakum, 2003: Orographic influences on the mesoscale structure of the 1998 ice storm. Mon. Wea. Rev., 131 , 2750.

    • Search Google Scholar
    • Export Citation
  • Rogers, E., T. L. Black, D. G. Deaven, G. J. DiMego, Q. Zhao, M. E. Baldwin, N. W. Junker, and Y. Lin, 1996: Changes to the operational “early” eta analysis/forecast system at the National Centers for Environmental Prediction. Wea. Forecasting, 11 , 391416.

    • Search Google Scholar
    • Export Citation
  • Saucier, W. J., 1955: Principles of Meteorological Analysis. University of Chicago Press. 438 pp.

  • Schultz, D. M., 2001: Reexamining the cold conveyor belt. Mon. Wea. Rev., 129 , 22052225.

  • Schultz, D. M., and C. F. Mass, 1993: The occlusion process in a midlatitude cyclone over land. Mon. Wea. Rev., 121 , 918940.

  • Schultz, D. M., D. Keyser, and L. F. Bosart, 1998: The effect of large-scale flow on low-level frontal structure and evolution in midlatitude cyclones. Mon. Wea. Rev., 126 , 17671791.

    • Search Google Scholar
    • Export Citation
  • Seeley, D. A., 1921: Heavy snowstorm in southern Michigan, November 8–9, 1921. Mon. Wea. Rev., 49 , 610.

  • Stoelinga, M. T., J. D. Locatelli, and P. V. Hobbs, 2000: Structure and evolution of winter cyclones in the central United States and their effects on the distribution of precipitation. Part VI: A mesoscale modeling study of the initiation of convective rainbands. Mon. Wea. Rev., 128 , 34813500.

    • Search Google Scholar
    • Export Citation
  • Stoelinga, M. T., J. D. Locatelli, and P. V. Hobbs, 2002: Warm occlusions, cold occlusions, and forward-tilting cold fronts. Bull. Amer. Meteor. Soc., 83 , 709721.

    • Search Google Scholar
    • Export Citation
  • Wakimoto, R. M., C. H. Liu, W-C. Lee, P. H. Hildebrand, and H. B. Bluestein, 1996: ELDORA observations during VORTEX 95. Bull. Amer. Meteor. Soc., 77 , 14651482.

    • Search Google Scholar
    • Export Citation
  • Weiss, C. C., and H. B. Bluestein, 2002: Airborne pseudo–dual Doppler analysis of a dryline–outflow boundary intersection. Mon. Wea. Rev., 130 , 12071226.

    • Search Google Scholar
    • Export Citation
  • Young, M. V., G. A. Monk, and K. A. Browning, 1987: Interpretation of satellite imagery of a rapidly deepening cyclone. Quart. J. Roy. Meteor. Soc., 113 , 10891115.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 360 84 1
PDF Downloads 195 63 0

High-Resolution Observations of the Trowal–Warm-Frontal Region of Two Continental Winter Cyclones

View More View Less
  • 1 Department of Atmospheric Sciences, University of Illinois at Urbana–Champaign, Urbana, Illinois
Restricted access

Abstract

This paper compares the structure of the trough of warm air aloft (trowal)–warm-frontal region of two continental wintertime cyclones. The cyclones were observed over the central Great Lakes region during the Lake-Induced Convection Experiment/Snowband Dynamics Project field campaign. The cyclones had different origins, with the first forming east of the Colorado Rockies and the second forming over the Gulf of Mexico. They were associated with different upper-level flow regimes, one located just north of a nearly zonal jet and the other located just west of a nearly meridional jet. Both storms produced heavy swaths of snow across the states of Illinois, Wisconsin, and Michigan. High-resolution observations of frontal structure were made during flights of the National Center for Atmospheric Research Electra aircraft using dropsondes and the Electra Doppler Radar tail radar system. The high-resolution observations suggest a different arrangement of air masses in the trowal region compared with the classical occlusion model, where the trowal axis forms at the intersection of a warm front and a cold front that has overtaken and subsequently ascended the warm front. In both cyclones dry air intruded over the warm front, isolating the warm, moist airflow within the trowal airstream. Very sharp moisture gradients were present at the leading edge of the dry air in both cyclones. In each case, relative humidity differences of over 50% were observed over distances of 10–20 km. The thermal gradient near the leading edge of the dry air in one cyclone was diffuse, so that the moist–dry boundary could best be characterized as an upper-level humidity front. In the other cyclone, the thermal gradient was sharper and aligned with the moisture boundary and was best characterized as a cold front aloft. The analyses suggest that the classical conceptual model of the trowal, at least in some cyclones such as the two illustrated here, needs to be revised to include the possibility that the warm moist airstream aloft may sometimes be bounded on its south side by an upper-level front rather than a surface-based cold front. Since the two cyclones discussed here had different origins, tracks, and flow regimes, the similarity of their structure suggests that these features may be common.

* Current affiliation: University Corporation for Atmospheric Research/Unidata, Boulder, Colorado

+ Current affiliation: Goddard Earth Sciences and Technology Center, Baltimore, Maryland

Corresponding author address: Robert M. Rauber, Department of Atmospheric Sciences, University of Illinois at Urbana–Champaign, 105 S. Gregory St., Urbana, IL 61801. Email: rauber@atmos.uiuc.edu

Abstract

This paper compares the structure of the trough of warm air aloft (trowal)–warm-frontal region of two continental wintertime cyclones. The cyclones were observed over the central Great Lakes region during the Lake-Induced Convection Experiment/Snowband Dynamics Project field campaign. The cyclones had different origins, with the first forming east of the Colorado Rockies and the second forming over the Gulf of Mexico. They were associated with different upper-level flow regimes, one located just north of a nearly zonal jet and the other located just west of a nearly meridional jet. Both storms produced heavy swaths of snow across the states of Illinois, Wisconsin, and Michigan. High-resolution observations of frontal structure were made during flights of the National Center for Atmospheric Research Electra aircraft using dropsondes and the Electra Doppler Radar tail radar system. The high-resolution observations suggest a different arrangement of air masses in the trowal region compared with the classical occlusion model, where the trowal axis forms at the intersection of a warm front and a cold front that has overtaken and subsequently ascended the warm front. In both cyclones dry air intruded over the warm front, isolating the warm, moist airflow within the trowal airstream. Very sharp moisture gradients were present at the leading edge of the dry air in both cyclones. In each case, relative humidity differences of over 50% were observed over distances of 10–20 km. The thermal gradient near the leading edge of the dry air in one cyclone was diffuse, so that the moist–dry boundary could best be characterized as an upper-level humidity front. In the other cyclone, the thermal gradient was sharper and aligned with the moisture boundary and was best characterized as a cold front aloft. The analyses suggest that the classical conceptual model of the trowal, at least in some cyclones such as the two illustrated here, needs to be revised to include the possibility that the warm moist airstream aloft may sometimes be bounded on its south side by an upper-level front rather than a surface-based cold front. Since the two cyclones discussed here had different origins, tracks, and flow regimes, the similarity of their structure suggests that these features may be common.

* Current affiliation: University Corporation for Atmospheric Research/Unidata, Boulder, Colorado

+ Current affiliation: Goddard Earth Sciences and Technology Center, Baltimore, Maryland

Corresponding author address: Robert M. Rauber, Department of Atmospheric Sciences, University of Illinois at Urbana–Champaign, 105 S. Gregory St., Urbana, IL 61801. Email: rauber@atmos.uiuc.edu

Save