• Anthes, R. A., 1990: Advances in the understanding and prediciton of cyclone development with limited-area fine-mesh models. Extratropical Cyclones. The Erik Palmén Memorial Volume, C. W. Newton and E. O. Holopainen, Eds., Amer. Meteor. Soc., 221–253.

  • Bosart, L. F., and D. B. Dean, 1991: The Agnes rainstorm of June 1972: Surface feature evolution culminating in inland storm redevelopment. Wea. Forecasting,6, 515–537.

  • ——, and G. M. Lackmann, 1995: Postlandfall tropical cyclone reintensification in a weakly baroclinic evironment: A case study of Hurricane David (September 1979). Mon. Wea. Rev.,123, 3268–3291.

  • Brand, S., and C. P. Guard, 1979: An observational study of extratropical storms that evolved from tropical cyclones in the western North Pacific. J. Meteor. Soc. Japan,57, 479–482.

  • Browning, K. A., G. Vaughan, and P. Panagi, 1998: Analysis of an ex-tropical cyclone after reintensifying as a warm-core extratropical cyclone. Quart. J. Roy. Meteor. Soc.,124, 2329–2356.

  • Cullen, M. J. P., 1993: The unified forecast climate model. Meteor. Mag.,122, 81–94.

  • Davis, C. A., and K. A. Emanuel, 1991: Potential vorticity diagnostics of cyclogenesis. Mon. Wea. Rev.,119, 1925–1953.

  • DeMaria, M., 1996: The effect of vertical shear on tropical cyclone intensity change. J. Atmos. Sci.,53, 2076–2087.

  • DiMego, G. J., and L. F. Bosart, 1982a: The transformation of Tropical Storm Agnes into an extratropical cyclone. Part I: The observed fields and vertical motion computations. Mon. Wea. Rev.,110, 385–411.

  • ——, and ——, 1982b: The transformation of Tropical Storm Agnes into an extratropical cyclone. Part II: Moisture, vorticity, and kinetic energy budgets. Mon. Wea. Rev.,110, 412–433.

  • Emanuel, K. A., 1986: An air–sea interaction theory for tropical cyclones. Part I: Steady-state maintenance. J. Atmos. Sci.,43, 585–604.

  • Ferreira R. N., and W. H. Schubert, 1999: The role of tropical cyclones in the formation of tropical upper-tropospheric troughs. J. Atmos. Sci.,56, 2891–2907.

  • Flatau, M., W. H. Schubert, and D. E. Stevens, 1994: The role of baroclinic processes in tropical cyclone motion: The influence of vertical tilt. J. Atmos. Sci.,51, 2589–2601.

  • Foley, G. R., and B. N. Hanstrum, 1994: The capture of tropical cyclones by cold fronts off the west coast of Australia. Wea. Forecasting,9, 577–592.

  • Grønås, S., 1995: The seclusion intensification of the New Year’s Day storm 1992. Tellus,47A, 733–746.

  • Holland, G. J., 1997: Maximum potential intensity of tropical cyclones. J. Atmos. Sci.,54, 2519–2541.

  • Hoskins, B. J., and P. Berrisford, 1988: A potential vorticity view of the storm of 15–16 October 1987. Weather,43, 122–129.

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

  • Jones, S. C., 1995: The evolution of vortices in vertical shear. I: Initially barotropic vortices. Quart. J. Roy. Meteor. Soc.,121, 821–851.

  • Kornegay, F. C., and D. G. Vincent, 1976: Kinetic energy budget analysis during interaction of Tropical Storm Candy (1968) with an extratropical frontal system. Mon. Wea. Rev.,104, 849–859.

  • Lawrence, M. B., B. M. Mayfield, L. A. Avila, R. J. Pasch, and E. N. Rappaport, 1998: Atlantic hurricane season of 1995. Mon. Wea. Rev.,126, 1124–1151.

  • Matano, H., and M. Sekioka, 1971a: On the synoptic structure of Typhoon Cora, 1969, as the compound system of tropical and extratropical cyclones. J. Meteor. Soc. Japan,49, 282–295.

  • ——, and ——, 1971b: Some aspects of extratropical transformation of a tropical cyclone. J. Meteor. Soc. Japan,49, 736–743.

  • Mohr, T., 1971: Beitrag zur Umwandlung tropischer Wirbelstuerme in intensive aussertropische Zyklonen. Ber. Deut. Wetterdienstes,121, 1–32.

  • Neumann, C. J., B. R. Jarvinen, C. J. McAdie, and J. D. Elms, 1993:Tropical cyclones of the Atlantic Ocean, 1871–1992. U.S. Department of Commerce 193 pp. [Available from National Environmental Satellite, Data and Information Service, National Climatic Data Center, Asheville, NC 28801.].

  • Palmén, E., 1958: Vertical circulation and release of kinetic energy during the development of Hurricane Hazel into an extratropical storm. Tellus,10, 1–23.

  • Petterssen, S., and S. J. Smebye, 1971: On the development of extratropical storms. Quart. J. Roy. Meteor. Soc.,97, 457–482.

  • Reynolds, R. W., and T. M. Smith, 1994: Improved global sea surface temperature analyses using optimum interpolation. J. Climate,7, 929–948.

  • Rabier, F., E. Klinker, P. Courtier, and A. Hollingsworth, 1996: Sensitivity of forecast errors to initial conditions. Quart. J. Roy. Meteor. Soc.,122, 121–150.

  • Raymond, D. J., 1995: Regulation of moist convection over the west Pacific warm pool. J. Atmos. Sci.,52, 3945–3959.

  • Rotunno, R., and K. A. Emanuel, 1987: An air–sea interaction theory for tropical cyclones. Part II: Evolutionary study using a nonhydrostatic axisymmetric numerical model. J. Atmos. Sci.,44, 542–561.

  • Sanders, F., and J. R. Gyakum, 1980: Synoptic–dynamic climatology of the “bomb.” Mon. Wea. Rev.,108, 1589–1606.

  • Sekioka, M., 1956: A hypothesis on complex of tropical and extratropical cyclones for typhoon in middle latitudes, I. Synoptic structure of Typhoon Marie over the Japan Sea. J. Meteor. Soc. Japan,34, 42–53.

  • ——, 1970: On the behaviour of cloud patterns as seen on satellite photographs in the transformation of a typhoon into a tropical cyclone. J. Meteor. Soc. Japan,48, 224–232.

  • Shapiro, L. J., 1992: Hurricane vortex motion and evolution in a three-layer model. J. Atmos. Sci.,49, 140–153.

  • ——, and J. L. Franklin, 1995: Potential vorticity in Hurricane Gloria. Mon. Wea. Rev.,123, 1465–1475.

  • Shapiro, M. A., and D. Keyser, 1990: Fronts, jet streams and the tropopause. Extratropical Cyclones. The Erik Palmén Memorial Volume, C. W. Newton and E. O. Holopainen, Eds., Amer. Meteor. Soc., 167–191.

  • Sinclair, M. R., 1993a: Synoptic-scale diagnosis of the extratropicaltransition of a southwest Pacific tropical cyclone. Mon. Wea. Rev.,121, 941–960.

  • ——, 1993b: A diagnostic study of the extratropical precipitation resulting from Tropical Cyclone Bola. Mon. Wea. Rev.,121, 2690–2707.

  • Thorncroft, C. D., B. J. Hoskins, and M. E. McIntyre, 1993: Two paradigms of baroclinic-wave life-cycle behaviour. Quart. J. Roy. Meteor. Soc.,119, 17–55.

  • Thorpe, A. J., and S. A. Clough, 1991: Mesoscale dynamics of cold fronts—Structures described by dropsondings in Frontas 87. Quart. J. Roy. Meteor. Soc.,117, 903–941.

  • Wang, Y., and G. J. Holland, 1996: Tropical cyclone motion and evolution in vertical shear. J. Atmos. Sci.,53, 3313–3332.

  • Wu, C.-C., and K. A. Emanuel, 1993: Interaction of a baroclinic vortex with background shear: Application to hurricane movement. J. Atmos. Sci.,50, 62–76.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 12 12 12
PDF Downloads 3 3 3

The Extratropical Transitions of Hurricanes Felix and Iris in 1995

View More View Less
  • 1 Department of Meteorology, University of Reading, Reading, United Kingdom
  • | 2 Meteorologisches Institut, Universität München, Munich, Germany
Restricted access

Abstract

The extratropical transitions of Hurricanes Felix and Iris in 1995 are examined and compared. Both systems affected northwest Europe but only Iris developed significantly as an extratropical system. In both cases the hurricane interacts with a preexisting extratropical system over the western Atlantic. The remnants of the exhurricanes can be identified and tracked across the Atlantic as separate low-level potential vorticity (PV) anomalies. The nature of the baroclinic wave involved in the extratropical transition is described from a PV perspective and shown to differ significantly between the two cases.

The role of vertical shear in modifying the hurricane structure during the early phase of the transition is investigated. Iris moved into a region of strong shear. The high PV tower of Iris developed a marked downshear tilt. Felix moved into a vertically sheared environment also but the shear was weaker than for Iris and the PV tower of Felix did not tilt much.

Iris maintained its warm-core structure as it tracked across relatively warm water. It moved into the center of a large-scale baroclinic cyclone. The superposition of the two systems gave rise to strong low-level winds. The resulting strong surface latent heat fluxes helped to keep the boundary layer equivalent potential temperature (θe) close to the saturated equivalent potential temperature of the underlying sea surface temperature. This high equivalent potential temperature air was redistributed in the vertical in association with deep convection, which helped maintain the warm core in a similar way to that in tropical cyclones.

Felix did not maintain its warm-core structure as it tracked across the Atlantic. This has been shown to be linked to its more poleward track across colder water. It is argued that negative surface fluxes of latent and sensible heat decrease the boundary layer θe, resulting in low-cloud formation and a decoupling of the cyclone boundary layer from the the deep troposphere.

In order to forecast these events there is a need for skill in predicting both the nature of the large-scale baroclinic wave development and the structural evolution of the exhurricane remnants.

Corresponding author address: Dr. Chris Thorncroft, Department of Meteorology, University of Reading, 2 Earley Gate, Reading RG6 2AU, United Kingdom.

Email: swsthcri@met.reading.ac.uk

Abstract

The extratropical transitions of Hurricanes Felix and Iris in 1995 are examined and compared. Both systems affected northwest Europe but only Iris developed significantly as an extratropical system. In both cases the hurricane interacts with a preexisting extratropical system over the western Atlantic. The remnants of the exhurricanes can be identified and tracked across the Atlantic as separate low-level potential vorticity (PV) anomalies. The nature of the baroclinic wave involved in the extratropical transition is described from a PV perspective and shown to differ significantly between the two cases.

The role of vertical shear in modifying the hurricane structure during the early phase of the transition is investigated. Iris moved into a region of strong shear. The high PV tower of Iris developed a marked downshear tilt. Felix moved into a vertically sheared environment also but the shear was weaker than for Iris and the PV tower of Felix did not tilt much.

Iris maintained its warm-core structure as it tracked across relatively warm water. It moved into the center of a large-scale baroclinic cyclone. The superposition of the two systems gave rise to strong low-level winds. The resulting strong surface latent heat fluxes helped to keep the boundary layer equivalent potential temperature (θe) close to the saturated equivalent potential temperature of the underlying sea surface temperature. This high equivalent potential temperature air was redistributed in the vertical in association with deep convection, which helped maintain the warm core in a similar way to that in tropical cyclones.

Felix did not maintain its warm-core structure as it tracked across the Atlantic. This has been shown to be linked to its more poleward track across colder water. It is argued that negative surface fluxes of latent and sensible heat decrease the boundary layer θe, resulting in low-cloud formation and a decoupling of the cyclone boundary layer from the the deep troposphere.

In order to forecast these events there is a need for skill in predicting both the nature of the large-scale baroclinic wave development and the structural evolution of the exhurricane remnants.

Corresponding author address: Dr. Chris Thorncroft, Department of Meteorology, University of Reading, 2 Earley Gate, Reading RG6 2AU, United Kingdom.

Email: swsthcri@met.reading.ac.uk

Save