sm?PTscattered cuzailuswith an occasional ShOWer in the area. All of the clouds were below 8,000 feet. The upper winds, however, showed a thick transitionalzone of variable winds with northerQ components between 15,000 ad 30,000 feet. Since there was no justificationfor believing that a rapid ch~e in the wind structure was imminent there was considerabledoubt expressed at the UOOM btiefing whether the “ winds would change sufficientlyto meet the radiologicalsafety requimnts. There was however, a reasonable expectation that these awkwani winds wouli ted to veer in such a manner that the northerly componentswould be eliminated within @ hours. Thus on the basis of unfavorablewinds the CommarxterJTE!7 postponed Yoke Day for 2k hours ad Yoke Day was now scheduled for 1 May. H Hour was unchanged from the previous schedule. On the new Yoke minus one morning, the upper winds had altered sufficientlyto indicate a new air flow was beginning to predominate. The winds becam light in velocity between 15,000 and 30,000 feet but were gradually assuming a persistent southerly component. Thus at the 11.00M”briefing, 30 April, a forecast of favorable cloud arxtwiti conditions was presented - the operation for Yoke Day was on. The weather recomaissance aircraft observationsduring the day confirmd the forecast for favorable cloui ami wind conditions for Yoke day, a considerabledhunution of the moisture content had been noticed in the lowest 10,000 feet ad this virtually guaranteed a minimum of oumulus activity for Yoke day. At the 1800M btiefing on Yoke minus one the favorableweather SECTYON XII 46