utilized in operational planning of RadSafe factors. ad began to deteriorate at “ITEN" minus 2 days. A favorable upper wind pattern a i* Ve . “y 4 ; i 4 yo Tho wind pattern ot the H minus 30 with a trend towards hours Commander's bricfing indicated FAVORASLE RadSafe fectors CONDITIONALLY FAVORABLE, Ab the H minus 18 hours bricfing o continued deteriore:tin up the scheduled shot tin of the wind pettcrn was forecast and it was decided to move ag far as possible, from C930M to one-half hour before suivise, by the H minus 6 would be sus- which hour Commander's briefing the FAVORABLE trend appeared to be one tained, This took into account the considerations that unfavernble northerly wind Six hours coempononts above 20,000 fect would remain very light for at lonst three to aftor shot time. All heavy fall-out (significant as a heelth hagard) was forecast to be in a: ddtaavind cone-of 220° to 280° truc, with radial distance up to 4,0 miles, Hoaviest concentration at upper Lovels was forecast to fall-out southwest from zero point. Primary fall-oub occurred cssentially according to thig pattern. be Howe ever, WNIWETOK ISLAND received some delayed fall-out above oxpectation for two roaq & sons: (1) light, variable wind ccnditions shove 20,000 fest gave a larger spread to the predicted areas of fall-out southwest of zcro and, (2) already changing wind pate vern aloft began to change move ranidily at ii plus 3 hours to a more normal trade wind flow', Ce Fall-out on ships of Task Group 3.3 in the southern part of the Lagoon and on EWIWETOK ESLAND was gonerall in two waves, tensity up to 40 mr/hr, occurred at 1 plus 4 heurs, The first one, with sustaincd inThe second wave, with sustained intensities up to 100 mr/hr occurred at i plus 10 hours on Une oxtrenme southorly por-tion of the atoll, d. By 1730M, sufficient cloud bracking by aircraft head been donc to cable a snap picture of boundaries te be defined for estimating probable foll-out duratio: For distances up to 100 miles south and -north of the atoll, planes mide no contact with the atomic cloud at 10,000 foot levels. However, upwind (i.e., to oast and east-southcast) of the atoll, nilanes made contact at 10,000 and 25,000 foot levels at 1500M while « plane at 1900M, 120 miles cast of the atoll, did not moke contact. &, Cn the basis of the obsorved winds in the Lower 9000 fect, a forceast was made by the RadSafe Officer of JTF-3 to Task Unit 3.1.5 (RadSafe Center) thet th H plus LO hours wave of fall-out should commence decreasing «bt ZOOOM or about A plus 14 hours, Pe Ab no time did these Levels, however, reach significant preportions as & health hazard from the standpoint of permissible cxposure Levels or from particlo ft2