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<br />useful mesoscale information is available. Although information at <br />this scale will not resolve cloud-scale phenomena, it will provide <br />meso-p information regarding larger scales of natural variability and <br />mesoscale triggering controls. <br /> <br />Three-dimensional model analyses show that meso-p scale second- <br />ary circulations occur in the clear air near developing convective <br />complexes, lines and squall lines (Fritsch and Chappell, 1980a). <br />These secondary circulations produce large amounts of warming at <br />mid-tropospheric levels which may induce mesolow circulations and <br />produce significant low-level convergence (Fritsch and Chappell, <br />1980b). <br /> <br />A three-dimensional, mesoscale, primitive equation model <br />developed by Anthes and Warner (1978) indicates the need for high- <br />resolution surface observations to define mesoscale convergence <br />patterns. Four experiments run in this model show the importance of <br />scale in defining the mesoscale forcing (Warner et al., 1978). <br />Model simulations of a thermally driven circulation in the vicinity <br />of Chesapeake Bay resulted in circulations similar to those which may <br />be associated with cloud lines on the plains. This simulation <br />produced a sea breeze convergence line 20-30 km wide in the planetary <br />boundary layer (PBL), similar to that of Pielke and Mahrer (1975, <br />1978) who simulated sea breeze conditions in Florida. <br /> <br />Model analyses by Pielke and Cotton (1977) showed the importance <br />of superimposed upper-level synoptic disturbances and surface con- <br />vergence in triggering a heavy rainfall event. <br /> <br />22 <br />