om EVENT The device was detonated at 0630 hours local (M), 27 March 1954 as a water surface shot from a barge in the BRAVO crater in approximately L10 feet of water. Yield was approximately 11 megatons. The day before ROMEO event, scattered patches of stratocumulus, a normal amount of cumulus (2/8 to 3/8), and broken to overcast cirrus (more than half-sky coverage) prevailed over the northern Marshalls. The cirrus had been extremely persistent for a period of 10 days. An aerial weather observer in an aircraft at 10,000 feet near ground zero reported 6/8 to 8/8 cirrus until H minus 23 hours. Fifteen minutes later he reported 4/8 cirrus, and thereafter only 3/8 cirrus. 7 Several showers occurred near Eniwetok during the evening before the shot. The circulation at the time of ROMEO event was marked by an extenSive clockwise outdraft. It existed at all levels from 10,000 feet to the tropopause and was centered approximately 550 miles east-—northeast of Bikini. This system produced a deep layer of winds with pronounced Southerly components over the northern Marshalls. Moderate strength hortheast trades prevailed near the surface. At shot time a consensus of the observations taken at Bi; ..11 from the command ship by sixteen trained weather observers ara forecasters was 2/8 cumulus, bases 1,800 feet, tops 4,000 to 5,000 feet and 3/8 cirrus at approximately 40,000 feet, as shown in Figures 8, 9 and 10. Showers were observed. No Identics.. nditions were reported at Erniwetok.