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I I I I I I I I I I I I I I I I I I I of a frontal system. Echoes were typically small and scattered. First echoes appeared to be by the warm rain process and cloud tops seldom exceeded 17,000 ft (_100C). Both of these cases should have had potential dynamic seedability, particularly for the small to medium sizes. The two other control cases were associated with frontal systems and there existed mid-level stable regions that controlled the vertical development of the convective cells. Case vn was an example in which cloud water contents were good and cloud tops were at 18, 000 ft (_80C). Dynamic seeding for the larger turrets should have produced subsequent vertical growth. Case vrn was a similar situation with a mid-level stable region capping the warm rain generated showers. Seeding potential appears good for medium to large turrets. Of the seeding cases, one was in unstable air simi- lar to controls n and IV; 3 cases had mid-level stable layers similar to controls vn and VIII, one occurred with a stable lower region, and one with an intense mid-level inversion. Case IX was the unstable situation and the time- height cross sections show that the physical response to the seeding event is very good. Cells properly seeded show good vertical growth and the subsequent fallout patterns have prolonged duraiion and multiple surges of core area fallout. Case 1, III, and IX are all characterized by mid..level stable layers which i"nfluEmce vertical cloud development. Like control cases, VII and Vill, the initial showers seems to be warm phase generated With evi(j-ence of only a weak ice phase involvement. Active seeding in these cases results in a sequence of physical events which indicates vertical growth beyond the mid-level stable 116