lL March 1954 poNe 4 ‘ MEO>=4NDUM FOR RECORD: Command Briefing, SUBJECT: Lenders present: 0000, 1 March 1954 Gen. P.W. Clarkson, Gen. B. UcGinley, vel. He Estes, or. A.C. Graves, Dr. W. Ogle, ar. J. Reeves, o>. De Sewell , Capt. W.L. Koickeroocker, Col. W.S. Cowart, Capt. R. a. Maynerd, Lt Col C.D. Bonnet, Lt Col R.&. House. 1. Io generel, the forecast presented at the midnight briefine was confirmed, except tnoat in the levels beswen 5 end 15 thousend feet toe forecast was light and variable. Is an atterpt to celizeate direction to these winds, it was determined that the best forecest that could be given was for vue 10 thousand foot level. This was forecest to be westerly ét 10 knots as the cost pessiszristic situation. Consequectiy woe bososgrerh plot vas zade using the 10 thousend foot westerly wind in arder to present the most pessimistic situation which would occur. This picture save resultant winds in the direction of Ecngelap end Rongerik, cowever, it was cansidered thet the Qistence to Ronselap and Rongerik cocpared to the resultant Wiad speeds were suco that no fall-out snould reach those atolls. From the forecast hodiogreph the time of travel to Rongelap w-uldé ceve ceeo about 12 to 15 hours. The hodograph plot did bowever scow that certeinly Takr site would ce heavily contarinated, end most likely NaN. The hodogreph gave two general fall-out areas. ‘The lower level running from 260 degrees around throug south to 90 degrees with a six hour fall-out line in the directica cf the populeted atolls in the southeast quadrant about 15 te 20 miles out fram ground zero. The high level redex ran frca about 45 degrees to SO degrees with a six hour fall-out line to 7C miles. (Since the 6 hour fall-out lines were computed on abdcus icc micron particle size, it vas recommended that the di stance ne doubled for safety. This acounted to considering particle sizes dovn to about 70 microns). / 2. N@ ekange in the 72 hour cloud trejectories. 3. BdMSare Outlooks were =odified as follows: a. Bikini atoll was changed from favcrable to unfavorable. be Eniwetok etoll recained very favcrabdle. c. Ujelang etoll remeinec very favorebdle. a=