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analysis and difficulties introduced by changes in cropping patterns, numbers of fanners buying hail insurance, and in methods of recording hail losses over the years. It was found that the hail loss records improved considerably just after Wodd War II in terms of both coverage and standardization. The hail data were acquired in early 1986. Because the target area is located at the southwest comer of Kansas, it was necessary to obtain data from six states to perform the evaluation. The data from Kansas, Nebraska, Colorado and Oklahoma were obtained on magnetic tape. The data from New Mexico and Texas were obtained in printed form and had to be entered into the computer through the keyboard. The hail data obtained were the loss-cost ratios by township. The loss-cost ratio is defmed as the ratio of the monetary damage inflicted by hail to the total value of the insured crop. Some care is required in computing a loss-cost ratio for a given situation, considering that some crops are only partially insured and many policies have deductible clauses. The CHIAA goes to great lengths in adjusting data for different types of policies and also adjusts for different types of crops. The fmal numbers provided by CHIAA can be thought of as the fraction of the insured crop value that would have been lost to hail if all of the damaged fields had been planted to wheat. Even so, one must recognize that crop-hail damage is a function of factors other than the size and number of hailstones falling. The timing of the hailstorms and the intensity of accompanying wind and rain also enter into the fmal statistics. Only sea4lonal values were available; that is, there is no information regarding the dates or times of individual storms. Organization of the township loss-cost data onto the grid used in the evaluation required considerable time. Computer programs were written to handle the different surveying systems used in the various states. The center of each township within or bordering the grid was assigned a latitude and longitude. In calculating the loss-cost value to be assigned to each grid point, we considered all townships whose centers lay within one half of a grid spacing from that point and combined them using a weighting system. The calculation of the ratio for a grid point typically involved combining data from six to nine townships. Once the loss-cost data were gridded and stored in the computer, they were in an easy form for statistical manipulation and for viewing on graphic displays. The hail damage pattern for any year could be viewed with color coding to represent the severity of the damage. Year-to-year differences could be easily seen by successively viewing yearly values or by actually plotting the changes from year to year. Because of space limitations, we can include only a few samples of the maps which were actually viewed on the screens. For example, figure 4.1 shows the average loss-cost ratio at each grid point for all of the no-seed years (1948 to 1974 inclusive) as viewed on a color display. .... 4.2 Relationship of Hail Severity to Elevation It is well known that the severity of hail decreases as one proceeds from west to east across Kansas (figure 4.1). During the initial review of the hail data, a strong positive correlation (r=O.91) was found between the loss-cost ratios by township and the ground elevation in each township. This correlation could be due to a tendency for thunderstorms forming over high ground to be more severe than those over lower ground and therefore to generate more or larger hailstones. It could also be related to the melting of hailstones, as hailstones falling at low-elevation sites must fall further through warm, moist air than those falling on higher terrain. The latter idea was pursued quantitatively through the use of a detailed hailstone model, which allowed for melting during fall, 26