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form of a dense wet snowfall but heavy rains fell over the plains. The storm began on the afternoon of 17 May in New Mexico and Kansas. Precipitation ended at most of the Colorado stations during the after- noon of 19 May. At Lake Maloya, New Mexico, 13.59 inches of precipi- tation occurred in 48 hours, with 11.28 inches measured during the 24-hour period ending at 4 p.m. on 19 May. This station recorded the greatest amount of precipitation during the storm. 3-10. Major flooding occurred in the Arkansas River from Pueblo to John Martin Dam and in the reach of the Purgatoire River from Trinidad to the mouth, The flood on the Purgatoire River exceeded the flows ex- perienced during the 1942 flood. The peak flow of record (70,000 c.f.s.) on the Purgatoire River near Las Animas was established on 20 May 1955. The Arkansas River flood peak at Pueblo was 11,100 c.f.s. As the flood progressed downstream, the peak increased to 50,000 c.f.s. at La Junta and caused major flood damage to North La Junta, a residential area across the river from La Junta. At Las Animas the peak measured 44,000 c.f,s. but due to a very successful flood fight, no serious flooding occurred at Las Animas. The peak inflow to John Martin Reservoir was 88,000 c.f,s. and the flood volume at the reservoir was 260,000 acre- feet. 3-11. Very little inflow was produced by the upper tributaries. Fountain Creek had a peak discharge of about 5,000 c.f.s. at the mouth. The St. Charles River had a peak .of about 20,000 c.f.s. at the mouth. The peak discharge of the Huerfano River near Undercliffe was 11,300 c.f.s. The peak discharge of the Apishapa River near Fowler was 17,000 c.f.s. and for Timpas Creek near Rocky Ford, the peak flow was 7,500 c.f.s. 3-12. PZood of June 1965.- The flood-producing rains of 13-19 June 1965 were the culmination of a strong and persistent weather pat- tern which existed over the western United States for about 4 months. The general pattern of the upper level windflow was out of the Gulf of Alaska, down the west coast, across southern California, back up through Arizona and New Mexico, and over the high plains. This gen- eral pattern of upper air circulation was present throughout the storm period and was most pronounced on 16-17 June with unseasonably cool air aloft at 20,000 feet. By 14 June, the increasing surface pressures over the central plains coupled with a low-pressure area centered over Chihuahua, Mexico, induced an inflow of moist Gulf air into northeastern New Mexico and eastern Colorado, damming it up against the Rocky Mountains beneath the cold air aloft. This combi- nation of surface and upper air conditions resulted in extremely un- stable atmospheric conditions, and reinforced by mechanical lifting (due to the upslope of the terrain) and convergence (due to the low- level pressure pattern), produced phenomenal rains. 3-13. During the period 13-19 June heavy precipitation occurred over a large part of the Arkansas River subbasin in Colorado east of Canon City and over the Canadian River Basin in northeastern New Mexico. 15