on November 16, 1997 at 13:33:18:
In a thermodynamically unstable environment, horizontal inflections
in boundary layer convergence lines are preferred areas of convective
development due to enhanced lifting of air parcels at these locations.
Horizontal wave patterns or shearing instabilities have been observed
along many boundary layer convergence lines (e.g., McCarthy and
Koch 1982; Carbone 1982,1983; Mueller and Carbone 1987; Wakimoto
and Wilson 1989; Kingsmill 1995). They usually manifest themselves
as a series of small scale vertical vorticity maxima (i.e., misocyclones)
spaced at regular intervals along a boundary. These phenomena (what
I term inflections) have most often been used in the explanation
of non-supercell tornadogenesis. However, in the more recent literature,
there has been speculation that inflections play a role in convective
initiation (Kingsmill 1995; Lee and Wilhelmson 1997). These studies
have focused on the convergence and vertical velocity maxima that
form adjacent to each of the vertical vorticity maxima. If the convergence
and vertical velocity maxima are persistent, enhanced lifting of
air parcels and convective development at these locations may result.
Further study and additional datasets are required to better understand
Prior to the development of deep convection, use clear-air Doppler
radar (WSR-88D, DOW, ELDORA) to identify a boundary layer convergence
line with inflection(s). Sample the kinematic structure of the boundary
within the full-depth of the boundary layer with clear-air Doppler
radar measurements from the dual-DOW system, and/or ELDORA. Sample
the thermodynamic structure of the boundary within the full depth
of the boundary layer with M-CLASS, mobile surface mesonet, ground-based
and airborne DIAL water vapor lidar, and mobile ground-based water
vapor radiometer. In situ aircraft measurements could be used to
validate the remotely sensed kinematic and thermodynamic structures.
Monitor for the development of deep convection with WSR-88D, DOW
s, and ELDORA.
Carbone, R. E., 1982: A severe frontal rainband. Part I: Stormwide
hydrodynamic structure. J. Atmos. Sci., 39, 258- 279.
Carbone, R. E., 1983: A severe frontal rainband. Part II: Tornado
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Kingsmill, D. E., 1995: Convection initiation associated with
a sea-breeze front, a gust front, and their collision. Mon. Wea.
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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.
McCarthy, J., and S. E. Koch, 1982: The evolution of an Oklahoma
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Mueller, C. K., and R. E. Carbone, 1987: Dynamics of a thunderstorm
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Wakimoto, R. M., and J. W. Wilson, 1989: Non-supercell tornadoes.
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