NWC REU 1998



Size, Spacing, and Predictability of Deep Convective Storms

Russell C. Teabeault and Kelvin Droegemeier



A three dimensional numerical model s used to conduct a preliminary study of the factors responsible for determining the size and spacing of deep convective storms. Two sets of simulations are conducted in a 80X80 km domain with periodic lateral boundaries. The first uses random potential temperature perturbations to initiate convection so that the scale and spacing of the storms may be determined "naturally". The second uses a checkerboard pattern of various sized potential temperature perturbations to force storms at particular scales and spacings. For the two sets of experiments, simulations were run with both a calm and strongly sheared wind profile' the thermodynamic profile was the same in all cases.

When random forcing is used, supercell storms form in a the strong shear environment and tend to be larger in size than the single-cells in the counterpart no-wind run. When perturbations of a particular scale are used to trigger convection, the resulting storms seem to have a "memory" of that scale which tends to last longer as the size of the initiating disturbances is increased. Nonetheless, the supercell storms in strong shear tend to be larger in these experiments as well. It is apparent that the environment, particularly the vertical shear, plays a major and perhaps, the key role in determining storm size and spacing.

Paper available upon request.