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(1) the air-mass storm complex (2) multiple celled storms (3) the squall line Air-mass storms often become complex after starting out as an isolated cloud system with a well-organized cloud base and its main new growth updraft area usually visible somewhere around its base. Multiple cloud turrets often develop around the initial "parent" storm and subsequent storm movements can become erratic depending upon several factors such as its severity, terrain effects, dynamic factors within the storm, cloud height, variability of wind speed and direction with height and the blocking of steering winds caused by large upwind cloud systems. Air-mass storm complexes often transition into a large, multi- celled systems. Fig. 2 shows a "classic" storm with new growth on its left side. Updrafts found on the upwind side of a storm' s direction of movement are termed "trailing" or "back" side; the "front" side is on the downwind side, its leading edge. Most often, important updrafts to the hail process are found along its trailing edge below cloud base at some distance behind the precipitation. Air-mass storms can transition into a line of storms containing multiple cells showing characteristics more similar to those of a small squall line. During the gradual development of these multi- cellular lines, cloud base updrafts frequently shift around although they are still found around some of the individual cell elements comprising it, making proper cloud base treatment quite difficult. The updraft locations important to the hail process on these type qf cloud systems are along a line on its front side, running from a few miles to many miles in length. Other times, the best seeding area may 'be around only one end of the line. Multi-celled lines may also appear as a remnant of a weakened squall line or as part of a line of storms associated with fronts, surface troughs and thunderstorm outflows. Under some conditions multi-celled storms may become very large, developing several new growth areas simultaneously with distinct storm "cores" growing embedded in and around the periphery of the total cloud boundary while the cloud system is in transition from being a relatively small severe storm into a large supercell. One characteristic of supercells is that they exhibit a "right- turning" motion relative to the direction of the mean steering winds. Also, supercells can be quite dangerous as they can eject hail many in any direction, frequently throwing hail into the flight paths of seeding aircraft both at cloud base and cloud top; plus, supercells produce the most intense, destructive tornadoes. 8