_. ee TAB." UNTO -oy —the~tirst attempt to fire UNION was 16 April. The synoptic weather outloola om the morning of 15 April was such that scutherwesterly flow could be expectad the following mornings As a consequence the appropriate head= quartere# and task group staff personnel moved to BIKINI during the morning and early,afternoen of 15 April. At midnight, since moet of the factors to be considered were decidely unfavorable, the recommendation was made and accepted to postpone the shot for 24 hourse By 1500M 16 April neither the most pessimistic nor the most promising forecast appeared suitable. The decision was made te cancel the shot indefinitely, revert back to am 14-hour capability of firing, and return the staffs to ENTHEIOK. Northerly components between 20,000 and 60,000 feet persisted wmtil 25 April, at which time wea— ther systema were such that, by noon, a southerly trend could be forecast for the 26th. A decision was made to shect the following iay and to perform @ sector search (in addition to search of Area GREEN) 240 NM wide cut to 600 NM centered on true bearing 46° from GZ. Arrangements were then made to go afloat at BIKINI, internal and extemal agencies were notified of the proposed shot on 26 April, and the next Command Briefing was scheduled for 1700M@. In am attemp te get continuous wind-runs at RONGERIK, plans had been made to substitute a PC boat to house tha detachment afloat at 2ONGERIK instead of flying the detachment in for runs during daylight hours only. . Prior to departure from ENTVETORK, CINCP.CFLT was advised at appreaximate= ly 13304 that UNION was re-scheduled for 26061(M weather permitting, and that the forecast 72-hour air particle trajectories would be submitted later. The advisory further stated that no significant fall-out was forecast for popu= lated MiRSHALL Atolls and that no closure of air routes would be necessary. Further, the advisory included no health hazard problema forecast. for surface routes outside Area GREEN ani a statement to the effect that an intensive search of this area was being made, plua a 240 NM wide sector search ous to 600 NM centered on true bearing from GZ of 40°, CINCP..CFLT was requestei to divert all shipping cutside the new Danger Area and was advised that no mows transient shipping was in the area. By 1700M the observed lower lewals had become easterly to 10,000 and westerly to 18,000, nevertheless the decision was made to continue pre-shot activities until at least midnight. At a speeial briefing held at 210QM the © observed winds were sanewhat less favorable in the lower levels, veering around counter-clockwise to 20,000 feet. Shot preparations were continued in the hope that the southwesterlies in the mid-levels would persist at BIKINT and at noints to the east. —~ At apnroximately 19COM the surface and air RADEXES were issued as follows Surface RADEX: True bearings from GZ 285° clockwise to 80° radial distance 100 NM for H to H plus 6 hours, plus a cireular XADEX around GZ of 20 NM radius, No]