What does "VV" in a METAR report indicate?

In a METAR report, "VV" signifies that the sky is obscured by surface-based clouds. This situation typically occurs when low clouds or fog cover the sky at or near the ground level, making it impossible to see the sky or any higher cloud layers. It informs pilots and weather observers that the visibility in terms of sky observation is compromised, which is critical information for flight preparation and safety.

The significance of this indication lies in the fact that pilots need to be aware of low visibility conditions that may affect their flight operations. Strategies for navigating in such conditions can differ greatly depending on the level of obscuration reported.

Recognizing "VV" is essential for flight planning and operation, as it provides immediate context for potential weather-related challenges. Other options describe different weather phenomena but do not specifically refer to the obscuration of the sky due to surface-based conditions, which is why they do not apply in this scenario.