TAB A LACROSSE EVENT OPERATION REDWING 1, The etortic device, LACROSSE, was detonated at OC75M, 5 May 4956 at the surface on the island of PURIT in the EhIVETCH Atoll. The LACROSSE cloud reached an altitude of epproxnately LC,C00 feet. The cloud sheared at erppreximetely 18,000 feet with the citer. and lower portion of the cloud moving West, the upver portior neving to the Northeast. The initial helicopter survey iniicated thet the fallout was developing as forecast. Pesed on the initial elicopter Survey ane aerial monitoring reports, reentry hour was established as O7LEt, 5 May 1956. All RADEX notices were withdraw at 1510M, 5 May 32956 and the ENIVETOK area was open te aircraft. The fallout prediction for LACROSSE was based or. e surface burst with a maximum yield on the order of 60 kilotons. The forecast 7 2. | fallout plot (see TAB B). shows the fallout fallinz to the Nertheast with long axes lying along a true beering of 50°. The rether limited information on fallout for LACROSSE prevents a quantitative comparison ose Bam of the actual and forecast pattarns. E COPY ATiSteee. BEST AVAILABL SS SRU=2O5= Taio WOUrcnws CUneloOlO Ur ~ dbvah af. = UW A A fA WVUe dey , ad FAUb SOCpTpP fa] 25Re > zt — ee, T- :