What does "PRFG" indicate in surface weather observation?

The term "PRFG" in surface weather observation stands for "partial fog". This code is used in meteorological reports to signify that fog is present but not uniformly throughout the area. Such distinctions are important in weather observations, as they can inform pilots, mariners, and ground personnel about visibility conditions.

Understanding that "partial fog" indicates variability in fog coverage provides valuable information that can affect decision-making in a variety of contexts. For example, while some areas may experience significantly reduced visibility due to fog, others may remain clear, which is crucial for safe navigation and operations. This differentiation can assist in assessing the potential impact of weather on travel and outdoor activities.

The other options, while they mention different weather phenomena, do not reflect the correct definition of the "PRFG" code used in weather observations.