the westerlies first appear has a wide range and the prediction of this height constitutes a complex forecasting problem, Eighty per cent of the time at Eniwetok, wind speeds at any level up to 50,000 feet may be expected to be thirty knots or less, However, in the area to the east of Eniwetok, the frequency of strong west winds increases considerably. During the latter part of the January through May period, westerly winds increase in speed in the upper levels. E. Tropopause. The tropopause is the transition zone between the troposphere and the stratosphere, It is most frequently found between 54,000 and 60,000 feet above the Marshalls. The temperature of the tropopause in this area will be minus seventy-five to eighty degrees centigrade with warmer temperatures above and below the tropopause, Temperatures near minus sixty-five degrees centigrade can be expected at 45,000 feet, F,. Typhoons. The months of January through April experience a minimum of typhoon activity in the Southwest Pacific area, Usually about two typhoons occur during this four-month period. During May, ty- phoon activity increases in the Western Pacific. The chance is re- mote, however, that Eniwetok or Bikini will be directly affected by a typhoon during this period. 164