“7 ;i m uke order of twelve to eighteen hours for significant | * 2 ¥O Occur. The variation in time arises fraz considera~ of wind shear, with more diffuse and less sigzuifticast ine 2aS ata given time associated with lesge anguler asd _, smear. For this reason, 1% was required that actuel wind _.sations and forecasts immadiately before shot tins and .wout Shot day be continuously considered in their relatica 2a forecast conditions for the first twenty-four hours i :36 shot. » PRS-SzoT BRIEFINGS: ~weShot ccoumand briefings: a. The following were presensed at Weather . Weather conditions during the five days prior to ' adicated a favorable trend for BRAVO day with easterly - alow 15,000 feet and winds of a southerly componest -. Tye situation presented at E-6 hours for the subsequest ~ period (18 hours efter shot time) was satisfaccary. The “~ -2 period to begin 18 hours after shot time was predicted ~ an unfavoreble trend as northwest winds were forecast ~@ 10,000 to 20,000 foot levels. FRadSafea (1) Resultant wind diagrams including latest . ™~™t winda and forecast winds for & Hour aad the 72 dsur cajectories, which gave a fellout pavtern in a narror . _ “" * # the east northeast end a wide (140°) sector to tbe “sh vary glow resultant winds. (See Figure 1). - :. (2) Surface radex, HE to E plus 6 hours. (3) Outiecks for: (See _ (a) Bikint: Unfavorable; Eniwetok: Farorabie; - Favorable, end the native populated atolis in sortheest L rrube ) © Albi «| ~geenaberenr @ ‘ de from ground zero favorable, since resultant winds is “Shion of these erees were considered too slow to move at fallout to the atolls involved. (>} Tesk Toree fleet: Favorable, provided 4 out at leest SO ciles. - mAh TF‘ ty ‘ . ot 1 wie os soe 3S i Gt Since radioactive parsicsle tra- ~" . determined primarily by the winds at each level, it is *- wd that winds must be fram favorable directions a> vasye * (shin the outer limits on fevorable directions durisse tke « .¢ fallout. The eriticel faliout period was considered te ! CJ SOF Pre TOTape cert 6. A critical problem in predicting fall~-sat ise ws forecasting the stability or lack of stability of tke .attern after snot time. ba FEE OF ° fa F-17a T-STE F-die wo TEETO LL ONY TORLLOSaSTT - . be * i om - een, ongp o-h-. Cavey wo wm swe at | | | |