PART SIX ZEBRA DAY 1. Introduction From yoke Day, 1 May, up through Zebra minus four days (1.1w) the weatbr deteriorated slcdy. During this period there were greater amounts of middle clouds ad cirro-etratusovercasts frequently prevailing. All evidence indicated that the Intertropical Convergence Zone was moving slowly northwti. The wind structure from 1 May to 11 May was om of slowly diminishing wind velocities in the lower 15 thousand feet. The pressure gradient between Wake Idand to the north and Eniwetok ad Rongerik to the south was gradually diminishing and there was very little evidence to believe that this situation would change appreciably for Zebra Day. The winds at levels frm 25 to 50 thousand feet were southerly in th Kwajalein area ani were westerly in the Eniwetok area. This clash of winds ami the resulting cmvergence euggeated a possible explanationof the large amount of cirrus cloudiness being observed. On Zebra plus five (10 ~) there was ● well.marked tro~h located just off the coast of Japan. In the past, troughs of thie nature had moved slowly towafi the Eniwetok area and had affected tlm wimt atructure ad weather, so as to make operations,when under the influence of such a “pressuretrough, haz-ous from a radiological SECTION XII 53 W-fl-H