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<br />Numerical model experiments by Keyser and Anthes (1982) show the <br />important effects of friction and horizontal shear within the PBL <br />which lead to a low-level vertical velocity jet in the convergence <br />zone ahead of a front. These results are similar to those observed <br />in this study in the Texas HIPLEX rawinsonde observation on <br />May 27-28, 1979, discussed in Section 4. <br /> <br />Simulations by Tripoli and Cotton (1980) using a three- <br />dimensional model (having horizontal spacing of 1 km over a central <br />area of 30 km and expanding to 5 km spacing outward to lateral <br />boundaries at 50 km) showed the nature of cumulus-scale interactions <br />with deep tropospheric flow. The simulation showed that deep cumulo- <br />nimbus formation over Florida results from extra-storm-scale forcing <br />which transports the moisture capable of supporting deep moist <br />convection. The importance of the vertical extent of moisture flux <br />and temporal continuity of moisture transport was shown in these <br />simulations. The sustained supply of moist static energy by meso- <br />scale lifting was critical to continual thunderstorm development. <br />They suggest that mesoscale rawinsonde information would be required <br />to properly understand the full extent of heat and moisture trans- <br />ports supporting mesoscale cumulonimbus development. <br /> <br />Recent modeling studies of factors that contribute to large var- <br />iations in the intensity of deep convection over south Florida showed <br />the importance of mesoscale convergence on cloud growth. Tripoli <br />and Cotton (1980) showed that the convergence of low-level moisture <br />was important to the evolution of sustained, vigorous convection when <br />the low-level wind shear was large. However, when shear was weak, <br /> <br />23 <br />