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I; 'i! <j empirically by matching the initial calculated not-seeded curve with the not-seeded historical curve in the section from A to B. This same correction factor is applied to the calculated seeded curve from A to C. In the region from B to C a separate adjustment factor is calculated for E~ach temperature category of the calculated not- seeded curve. The point D, called the cri,tical temperature, is where the historical curve starts to falloff due to a dearth of ice forming nuclei at warmer temperatures. The seeding is considered effective in a positive sense to the right of D and the historical curve is subtracted from the adjusted seeded curve beyond D, to find the seeding effect. The differences in each temperature category is multiplied by the frequency of occurrence and sUIDInled to get the net seeding effect with the assump- tion that only those categories with plus differences are being treated. The poten- tial, or percentage increase in precipitation which optimally effective cloud seeding could produce, is given by the ratio of the net-seeding effect (4.67 inches in the illustration) to the total historical precipitation (55.11 inches) as determined by summing the products of the mean precipitation and number of cases in each of the cloud top temperature categories. A value of 8.47% was calculated in the illustration. This represents the percentage increase in precipitation potentially available from cloud seeding during the snow accumulation season. The seeding would be practiced on all cases where cloud top temperatures were warmer than -25C, or 18.1% of the time. It must be remembered that the hourly precipitation data in the sample covers only 14 out of 24 hours and only cases where adequate sounding data were available~ The percentage increase factor thus derived can, however, be applied to all precipi- tation in the snow accumulation season to estimate the net seeding potential. The determination of the P-T curves for an upslope or a downslope location, in the absence of historical data, is a.chieved by applying the same overall adjustment factors as found for the crest station to the values calculated for an upwind, or a downwind location. The seeding effect is then the difference between the seeded and not-seeded adjusted, calculated values. In case precipitation records are available only at an upvTind, or a downwind station, then this is used to derive the adjustments to apply to the other locations. The procled4re thus far corrects for model errors in Item 1 of the list on page 1-6. Th,e errors of Item 3 are adjusted for by simply shifting the calculat- ed precipitation profile an approprIate distance upwind. Details of the proce- dure and curves for the various massifs appear in Appendix A. 1-9 .;