When the prevailing visibility changes from 2 to 3 statute miles, what is needed?

When the prevailing visibility improves from 2 to 3 statute miles, a special observation is required. This is because a change in prevailing visibility to a value that significantly affects aviation operations, particularly when the visibility increases by one statute mile, mandates a special observation to provide updated and accurate weather information.

Special observations are crucial in ensuring that pilots and air traffic controllers have the most current conditions, especially when visibility may impact safety and decision-making. Routine observations, on the other hand, are conducted at scheduled intervals and may not capture these critical changes immediately. While an hourly observation reflects conditions at a set time, it does not specifically account for significant changes like those seen in a special observation. Temporary observations are typically used for brief events or conditions, but in this case, a formal update is needed due to the improvement in visibility.

Thus, when there is an enhancement in visibility that could influence flight operations, issuing a special observation helps maintain situational awareness and safety in aviation.