Editorial Type:
Article
Article Type:
Research Article

Relationship between a Weakening Cold Front, Misocyclones, and Cloud Development on 10 June 2002 during IHOP

Nettie R. Arnott The Pennsylvania State University, University Park, Pennsylvania

Search for other papers by Nettie R. Arnott in
Current site
Google Scholar
PubMed Close
,
Yvette P. Richardson The Pennsylvania State University, University Park, Pennsylvania

Search for other papers by Yvette P. Richardson in
Current site
Google Scholar
PubMed Close
,
Joshua M. Wurman Center for Severe Weather Research, Boulder, Colorado

Search for other papers by Joshua M. Wurman in
Current site
Google Scholar
PubMed Close
, and
Erik M. Rasmussen National Severe Storms Laboratory, Norman, Oklahoma

Search for other papers by Erik M. Rasmussen in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Jan 2006
DOI:
https://doi.org/10.1175/MWR3065.1
Page(s):
311–335
Restricted access

Abstract

The finescale structure and evolution of a cold front in the presence of small-scale circulations are examined using overdetermined dual-Doppler syntheses of mobile radar data along with thermodynamic data and cloud imagery collected on 10 June 2002 during the International H2O Project (IHOP). Linear clear-air reflectivity maxima and open cellular convection intersect the cold front, causing spatial variations in convergence along the front. Small-scale vertical vorticity maxima (misocyclones) often are coincident with these intersections and are associated with vertical velocity maxima.

Throughout the deployment, trajectory analyses indicate that parcels entering the frontal circulation travel predominately in the along-front direction. During the first hour of the deployment, upward motion is nearly continuous along the front. Consequently, parcels remain in regions of upward motion as they move along the front, and many eventually ascend to cloud base. In response, a line of cumulus clouds develops along the front.

Later in the deployment, however, enhanced warming behind the cold front causes the frontal circulation to weaken. Small-scale features such as misocyclones play a larger role in organizing upward motion along the front than when the front was stronger. Misocyclones contort the weakened cold front and are associated with kinks in radar reflectivity and fractures in upward motion. Parcels moving along the front now experience regions of both upward and downward forcing due to this fracturing. Hence, many of these parcels do not retain upward motion long enough to reach cloud base, and clouds along the cold front dissipate in the dry air above the boundary layer. Parcels that remain coincident with upward motion maxima, such as those maxima associated with misocyclones, however, often still reach the top of the radar domain and presumably cloud base.

Corresponding author address: Yvette P. Richardson, Dept. of Meteorology, The Pennsylvania State University, 503 Walker Building, University Park, PA 16802. Email: yrichardson@psu.edu

Abstract

The finescale structure and evolution of a cold front in the presence of small-scale circulations are examined using overdetermined dual-Doppler syntheses of mobile radar data along with thermodynamic data and cloud imagery collected on 10 June 2002 during the International H2O Project (IHOP). Linear clear-air reflectivity maxima and open cellular convection intersect the cold front, causing spatial variations in convergence along the front. Small-scale vertical vorticity maxima (misocyclones) often are coincident with these intersections and are associated with vertical velocity maxima.

Throughout the deployment, trajectory analyses indicate that parcels entering the frontal circulation travel predominately in the along-front direction. During the first hour of the deployment, upward motion is nearly continuous along the front. Consequently, parcels remain in regions of upward motion as they move along the front, and many eventually ascend to cloud base. In response, a line of cumulus clouds develops along the front.

Later in the deployment, however, enhanced warming behind the cold front causes the frontal circulation to weaken. Small-scale features such as misocyclones play a larger role in organizing upward motion along the front than when the front was stronger. Misocyclones contort the weakened cold front and are associated with kinks in radar reflectivity and fractures in upward motion. Parcels moving along the front now experience regions of both upward and downward forcing due to this fracturing. Hence, many of these parcels do not retain upward motion long enough to reach cloud base, and clouds along the cold front dissipate in the dry air above the boundary layer. Parcels that remain coincident with upward motion maxima, such as those maxima associated with misocyclones, however, often still reach the top of the radar domain and presumably cloud base.

Corresponding author address: Yvette P. Richardson, Dept. of Meteorology, The Pennsylvania State University, 503 Walker Building, University Park, PA 16802. Email: yrichardson@psu.edu

Save
Cover Monthly Weather Review
Monthly Weather Review

  • Arnott, N. R., Y. P. Richardson, and J. M. Wurman, 2003: A solar alignment technique for determining mobile radar pointing angles. Preprints, 31st Conf. on Radar Meteorology, Seattle, WA, Amer. Meteor. Soc., 492–495.

  • Atkins, N. T., R. M. Wakimoto, and T. M. Weckwerth, 1995: Observations of the sea-breeze front during CaPE. Part II: Dual-Doppler and aircraft analysis. Mon. Wea. Rev, 123 , 944–969.

    • Search Google Scholar
    • Export Citation

  • Bargen, D. W., and R. C. Brown, 1980: Interactive radar velocity unfolding. Preprints, 17th Conf. on Radar Meteorology, Seattle, WA, Amer. Meteor. Soc., 278–283.

  • Barnes, S. L., 1964: A technique for maximizing details in numerical weather map analysis. J. Appl. Meteor, 3 , 396–409.

  • Biggerstaff, M. I., and J. Guynes, 2000: A new tool for atmospheric research. Preprints, 20th Conf. on Severe Local Storms, Orlando, FL, Amer. Meteor. Soc., 277–280.

  • Bluestein, H. B., 1993: Synoptic-Dynamic Meteorology in Midlatitudes. Vol II. Oxford University Press, 594 pp.

  • Byers, H. R., and H. R. Rodebush, 1948: Causes of thunderstorms of the Florida peninsula. J. Meteor, 5 , 275–280.

  • Fankhauser, J. C., N. A. Crook, J. Tuttle, L. J. Miller, and C. G. Wade, 1995: Initiation of deep convection along boundary layer convergence lines in a semitropical environment. Mon. Wea. Rev, 123 , 291–313.

    • Search Google Scholar
    • Export Citation

  • Ferrare, R. A., J. L. Schols, and E. W. Eloranta, 1991: Lidar observations of banded convection during BLX83. J. Appl. Meteor, 30 , 312–326.

    • Search Google Scholar
    • Export Citation

  • Hane, C. E., H. B. Bluestein, T. M. Crawford, M. E. Baldwin, and R. M. Rabin, 1997: Severe thunderstorm development in relation to along-dryline variability: A case study. Mon. Wea. Rev, 125 , 231–251.

    • Search Google Scholar
    • Export Citation

  • Hane, C. E., R. M. Rabin, T. M. Crawford, H. M. Bluestein, and M. E. Baldwin, 2002: A case study of severe storm development along a dryline within a synoptically active environment. Part II: Multiple boundaries and convective initiation. Mon. Wea. Rev, 130 , 900–902.

    • Search Google Scholar
    • Export Citation

  • Kessinger, C. J., P. S. Ray, and C. E. Hane, 1987: The Oklahoma squall line of 19 May 1977. Part I: A multiple Doppler analysis of convective and stratiform structure. J. Atmos. Sci, 44 , 2840–2864.

    • Search Google Scholar
    • Export Citation

  • Kingsmill, D. E., 1995: Convection initiation associated with a sea-breeze front, a gust front, and their collision. Mon. Wea. Rev, 123 , 2913–2933.

    • Search Google Scholar
    • Export Citation

  • Koch, S. E., M. desJardins, and P. J. Kocin, 1983: An interactive Barnes objective map analysis scheme for use with satellite and conventional data. J. Climate Appl. Meteor, 9 , 1487–1503.

    • Search Google Scholar
    • Export Citation

  • Lee, B. D., and R. B. Wilhelmson, 1997: The numerical simulation of non-supercell tornadogenesis. Part I: Initiation and evolution of pretornadic misocyclone circulations along a dry outflow boundary. J. Atmos. Sci, 54 , 32–60.

    • Search Google Scholar
    • Export Citation

  • Lee, B. D., R. D. Farley, and M. R. Hjelmfelt, 1991: A numerical case study of convection initiation along colliding convergence boundaries in northeast Colorado. J. Atmos. Sci, 48 , 2350–2365.

    • Search Google Scholar
    • Export Citation

  • Marquis, J. N., Y. P. Richardson, and J. M. Wurman, 2004: Observations of misocyclones along boundaries during IHOP. Preprints, 22d Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., CD-ROM, 16A.5.

  • Matejka, T., 2002: Estimating the most steady frame of reference from Doppler radar data. J. Atmos. Oceanic Technol, 19 , 1035–1048.

    • Search Google Scholar
    • Export Citation

  • Oye, R., and M. Case, 1995: REORDER—A program for gridding radar data: Installation and use manual for the UNIX version. NCAR, 22 pp. [Available from Field Observing Facility, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307.].

  • Oye, R., C. Mueller, and S. Smith, 1995: Software for radar data translation, visualization, editing, and interpolation. Preprints, 27th Conf. on Radar Meteorology, Vail, CO, Amer. Meteor. Soc., 359–361.

  • Parsons, D., T. Weckwerth, and M. Hardesty, 2001: Scientific overview document for the International H2O Project. Version 2.1, NCAR, 44 pp.

  • Pauley, P. M., and X. Wu, 1990: The theoretical, discrete, and actual response of the Barnes objective analysis scheme for one- and two-dimensional fields. Mon. Wea. Rev, 118 , 1145–1163.

    • Search Google Scholar
    • Export Citation

  • Rasmussen, E. N., R. P. Davies-Jones, and R. L. Holle, 2003: Terrestrial photogrammetry of weather images acquired in uncontrolled circumstances. J. Atmos. Oceanic Technol, 20 , 1790–1803.

    • Search Google Scholar
    • Export Citation

  • Rotunno, R., J. Klemp, and M. L. Weisman, 1988: A theory for strong, long-lived squall lines. J. Atmos. Sci, 45 , 463–485.

  • Weaver, J. F., and S. P. Nelson, 1982: Multiscale aspects of thunderstorm gust fronts and their effects on subsequent storm development. Mon. Wea. Rev, 110 , 707–718.

    • Search Google Scholar
    • Export Citation

  • Weckwerth, T. M., and R. M. Wakimoto, 1992: The initiation and organization of convective cells atop a cold-air outflow boundary. Mon. Wea. Rev, 120 , 2169–2187.

    • Search Google Scholar
    • Export Citation

  • Weckwerth, T. M., J. W. Wilson, and R. M. Wakimoto, 1996: Thermodynamic variability within the convective boundary layer due to horizontal convective rolls. Mon. Wea. Rev, 124 , 769–784.

    • Search Google Scholar
    • Export Citation

  • Weckwerth, T. M., and Coauthors, 2004: An overview of the International H2O Project (IHOP_2002) and some preliminary highlights. Bull. Amer. Meteor. Soc, 85 , 253–277.

    • Search Google Scholar
    • Export Citation

  • Wilson, J. W., and W. E. Schreiber, 1986: Initiation of convective storms at radar-observed boundary-layer convergence lines. Mon. Wea. Rev, 114 , 2516–2536.

    • Search Google Scholar
    • Export Citation

  • Wilson, J. W., and D. L. Megenhardt, 1997: Thunderstorm initiation, organization, and lifetime associated with Florida boundary layer convergence zones. Mon. Wea. Rev, 125 , 1507–1525.

    • Search Google Scholar
    • Export Citation

  • Wilson, J. W., G. B. Foote, N. A. Crook, J. C. Fankhauser, C. G. Wade, J. D. Tuttle, and C. K. Mueller, 1992: The role of boundary-layer convergence zones and horizontal rolls in the initiation of thunderstorms: A case study. Mon. Wea. Rev, 120 , 1785–1814.

    • Search Google Scholar
    • Export Citation

  • Wilson, J. W., T. M. Weckwerth, J. Vivekanandan, R. M. Wakimoto, and R. W. Russell, 1994: Boundary layer clear-air radar echoes: Origin of echoes and accuracy of derived winds. J. Atmos. Oceanic Technol, 11 , 1184–1206.

    • Search Google Scholar
    • Export Citation

  • Wurman, J., 2001: The DOW mobile multiple Doppler network. Preprints, 30th Int. Conf. on Radar Meteorology, Munich, Germany, Amer. Meteor. Soc., 95–97.

  • Wurman, J., J. Straka, E. Rasmussen, M. Randall, and A. Zahrai, 1997: Design and development of a portable, pencil-beam, pulsed, 3-cm Doppler radar. J. Atmos. Oceanic Technol, 14 , 1502–1512.

    • Search Google Scholar
    • Export Citation

  • Ziegler, C. L., and E. N. Rasmussen, 1998: The initiation of moist convection at the dryline: Forecasting issues from a case study perspective. Wea. Forecasting, 13 , 1106–1131.

    • Search Google Scholar
    • Export Citation

  • Ziegler, C. L., T. J. Lee, and R. A. Pielke Sr, 1997: Convective initiation at the dryline: A modeling study. Mon. Wea. Rev, 125 , 1001–1026.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 277 75 6
PDF Downloads 184 42 9