Valid periods ending at 0000Z shall be indicated as 24 . The 24 indication applies to all time group ending times. In the case of an amended forecast, or a forecast which is corrected or delayed, the valid period may be for less than 24 hours. For the TAFS issued while thes elocations are closed, the word NIL will appear in place of the forecast text. The wind, visibility, and sky condition elements are always included in the initial time group of the forecast.
Weather is included in the initial time group only if significant to aviation.
If a significant, lasting change in any of the elements is expected during the valid period, a new time period with changes is included. The forecast wind would remain the same as in the previous time period. Any temporary conditions expected during a specific time period are included with that time period. The wind group includes forecast surface winds. The contraction KT follows to denote the units of wind speed in knots.