Miniature Supercells in an Offshore Outer Rainband of Hurricane Ivan (2004)

Eastin, Matthew D.; Link, M. Christopher
July 2009
Monthly Weather Review;Jul2009, Vol. 137 Issue 7, p2081
Academic Journal
Airborne Doppler radar observations are used to document the structure of three miniature supercells embedded in an outer rainband of Hurricane Ivan on 15 September 2004. The cells were located more than 100 km offshore, beyond the Doppler range of coastal radars. The combination of large CAPE, large vertical wind shear, and moderate cell-relative helicity with an apparent midlevel dry air intrusion provided an offshore environment supporting rotating storms. Each shallow cell contained a ∼5–7-km-diameter mesocyclonic updraft with midlevel updraft and vorticity maxima that exceeded 6 m s-1 and 0.008 s-1, respectively. Such offshore structures are consistent with miniature supercells observed onshore in association with tropical cyclone tornado outbreaks. The strong updrafts resulted from a combination of kinematic convergence, thermal instability, and shear-induced vertical perturbation pressure gradients. Mesocyclone production largely resulted from the tilting and subsequent stretching of low-level horizontal streamwise vorticity into the vertical by the strong updrafts. Evidence of baroclinic contributions from inflow along cell-generated outflow boundaries was minimal. The miniature supercells persisted for at least 3 h during transit from offshore to onshore. Tornadoes were reported in association with two cells soon after moving onshore. These observations build upon a growing body of evidence suggesting that miniature supercells often develop offshore in the outer rainbands of tropical cyclones.


Related Articles

  • The 8 June 1995 McLean, Texas, Storm. Part II: Cyclic Tornado Formation, Maintenance, and Dissipation. Dowell, David C.; Bluestein, Howard B. // Monthly Weather Review;Nov2002, Vol. 130 Issue 11, p2649 

    On 8 June 1995, scientists participating in the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX) collected a unique dataset with the Electra Doppler Radar (ELDORA). The ELDORA observations document the sequential life cycles of storm-scale circulations associated with...

  • The 8 June 1995 McLean, Texas, Storm. Part I: Observations of Cyclic Tornadogenesis. Dowell, David C.; Bluestein, Howard B. // Monthly Weather Review;Nov2002, Vol. 130 Issue 11, p2626 

    On 8 June 1995 scientists participating in the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX) collected airborne Doppler radar data in a storm that produced a family of tornadoes near McLean, Texas. The Electra Doppler Radar (ELDORA) scanned three significant tornadoes...

  • Variational Analysis of Oversampled Dual-Doppler Radial Velocity Data and Application to the Analysis of Tornado Circulations. Xue, Ming; Liu, Shun; Yu, Tian-You // Journal of Atmospheric & Oceanic Technology;Mar2007, Vol. 24 Issue 3, p403 

    For the detection of severe weather phenomena such as tornados, mesocyclones, and strong wind shear, the azimuthal resolution of radial velocity measurements is more important. The typical azimuthal resolutions of 1° for the Weather Surveillance Radar-1988 Doppler (WSR-88D) radars and of...

  • Impact of Configurations of Rapid Intermittent Assimilation of WSR-88D Radar Data for the 8 May 2003 Oklahoma City Tornadic Thunderstorm Case. Hu, Ming; Xue, Ming // Monthly Weather Review;Feb2007, Vol. 135 Issue 2, p507 

    Various configurations of the intermittent data assimilation procedure for Level-II Weather Surveillance Radar-1988 Doppler radar data are examined for the analysis and prediction of a tornadic thunderstorm that occurred on 8 May 2003 near Oklahoma City, Oklahoma. Several tornadoes were produced...

  • Environmental Ingredients for Supercells and Tornadoes within Hurricane Ivan. Baker, Adam K.; Parker, Matthew D.; Eastin, Matthew D. // Weather & Forecasting;Feb2009, Vol. 24 Issue 1, p223 

    Hurricane Ivan (2004) was a prolific producer of tornadoes as it made landfall on the U.S. Gulf Coast. Prior researchers have revealed that the tornadic cells within tropical cyclone (TC) rainbands are often supercellular in character. The present study investigates the utility of several common...

  • Structure of a Midtropospheric Vortex Induced by a Mesoscale Convective System. Bluestein, Howard B.; Unruch, Wesley P.; Stein, Herbert // Monthly Weather Review;Feb97, Vol. 125 Issue 2, p1 

    On 9 June 1988 a mesoscale (;200-km diameter) convectively generated vortex (MCV) passed through the Colorado wind-profiling network. The generating convective system, which was too small to meet Maddox's mesoscale convective complex criteria, developed beneath a high-amplitude mid- and...

  • Doppler Radar Analysis of the Northfield, Texas, Tornado of 25 May 1994. Bluestein, Howard B.; Unruh, Wesley P.; Stein, Herbert // Monthly Weather Review;Feb97, Vol. 125 Issue 2, p1 

    A large tornado was observed near Northfield, Texas, on 25 May 1994 during the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX). An analysis of the tornado and its parent storm is discussed. Doppler wind velocity spectra of the tornado and its parent circulation, which...

  • Descending and Nondescending Tornadic Vortex Signatures Detected by WSR-88Ds. Trapp, R.J.; Mitchell, E.D.; Tipton, G.A.; Effertz, D.W.; Watson, A.I.; Andra Jr., D.L.; Magsig, M.A. // Weather & Forecasting;Oct99, Vol. 14 Issue 5, p625 

    Tornadic vortex signatures (TVSs) of 52 tornadoes were identified and analyzed, then characterized as either descending or nondescending. This characterization refers to a known tendency of radar-observed tornadic vortices, namely, that of their initial detection aloft and then of their...

  • Observations of Tornadoes and Other Convertive Phenomena with a Mobile, 3-mm Wavelength, Doppler.... Bluestein, Howard B.; Pazmany, Andrew L. // Bulletin of the American Meteorological Society;Dec2000, Vol. 81 Issue 12, p2939 

    Presents observations of tornadoes and other convective phenomena using a mobile Doppler radar in the spring of 1999 in the Southern Plains of the United States. Description of data collected in three supercell tornadoes; Discussion of several features related to tornadoes; Suggestion for...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics