When the observed prevailing visibility is between reportable values, how should it be rounded?

When dealing with observed prevailing visibility that falls between reportable values, it is standard practice to round to the nearest reportable value. This approach ensures that visibility reports remain consistent and usable for aviation operations. By rounding to the nearest value, it maintains the integrity of the data while still providing an accurate picture of the current visibility conditions.

For instance, if the visibility reads at a non-reportable value such as 4.5 statute miles, it would be rounded to the nearest reportable value of 5 statute miles. This method prevents ambiguity and aids in clarity for pilots and air traffic controllers who rely on these updates for safety and operational planning. Using nearest values aligns with the guidelines set by aviation weather reporting standards, ensuring that all stakeholders receive uniform and reliable information.