ner 1 March 1954 ON en MEO>4NDUM FOR RECORD: Ne SUBJECT: Command Briefing, 0000, 1 March 1954 Mexnbers present: Gen. P.W. Clarkson, Gen. &. UeGinley, zene He Estes, Dr. A.C. Graves, Dr. W. Ogle, br. J. Reeves, Dr. De. Sewell , Capt. W.L. Knickeroocker, Col. W.S. Cowart, Capt. R. a. Naynird, Lt Col ¢c.D. Bonnot, Lt Col R.& House. 1. In generel, the forecast presented at the sidnight briefings was confirmed, except that in the levels between 5 and 15 thousend feet tne forecast was light and variable. an atterpt to celinesate direction to these winds, it was Ta determined that the best forecest that could be given was for cue 10 thousand foot level. This was forecest to be westerly &t 10 knots as the most pessisristic situation. Consequently tne hodosreph plot vas made using the 10 thousend foot wester wind in arder to present the most pessimistic situation which would occur. This picture gave resultant winds in the direction of Rongelep end Rongerik, however, it was considered thet tue @istence to Ronselap and Rengerik cocpared to the resultant wind speeds were such that no fell~-out should reach those atolls. From the forecast hodogreph the time of travel to Rongelap wruld neve pean about 12 to 15 hours. The hodograph plot did however atow that certainly TARE site would de heavily contarinated, ena most likely N4N. The hodogreph gave two general fall-out areas. The lower level running from 260 degrees around through south to 90 degrees with a six hour fall-out line in the directica cf the populeted atolls in the southeast quadrent about 15 te 20 miles out froz ground zero. The high level radex ran froa about 45 decrees to 80 degrees with a six hour fall-out line to 70 miles. (Since-the 6 hour fall-out lines were computed on abcuts 105 micron particle size, it was recommsnded that the distance ne doubled for sefety. This acounted to considering particle sizes dovn to about 70 microns). / 2. NO change in the 72 hour cloud trejectories. 3. BddSafe Outlooks were xodified es follows: @. Bikini atoll was changed from feverable to unfevcrable. be Eniwetok etoll recained very favcrebdle. ec. Ujelang etoll remeinec very favoreble.