Definition
A label used on ATC radar weather displays to indicate that precipitation has been detected in an area, but the radar system cannot determine how strong that precipitation is. The return is present, but its intensity level cannot be classified.
Plain English
ATC's radar can see that something is showing up as weather in that area, but it can't tell the controller how heavy or light it is. So the controller passes that uncertainty on to the pilot.
Context Anchor
Seen in ATC radar weather displays and weather avoidance assistance when a controller is describing weather shown on radar.
Why Pilots Care
Unknown intensity removes the ability to judge whether the weather is light or severe, requiring extra caution or a route change.
Grounding Statement
If the display says INTENSITY UNKNOWN, the important point is not that the weather is weak; it is that its strength has not been identified.
Intuition Check
Do not read INTENSITY UNKNOWN as “no significant weather.” It means weather may be present, but its strength is not known from that display.
Example Sentence 1
Center advised us of an area of precipitation twenty miles ahead, intensity unknown, so we requested a twenty-degree right deviation.
Example Sentence 2
When the radar showed INTENSITY UNKNOWN ahead, the pilot elected to land at an alternate airport.