Definition
The time delay between when weather data is actually observed by a sensor (such as a NEXRAD radar) and when that data is displayed to the pilot in the cockpit. In NEXRAD products delivered to the cockpit via datalink, latency means the radar image you are viewing is not real-time — it shows weather conditions as they were several minutes ago, not as they are right now.
Plain English
The lag between when the weather actually happened and when it shows up on your screen. The picture you see is always a few minutes old.
Context Anchor
Seen in Next Generation Weather Radar system discussions and cockpit weather displays when judging how current a displayed weather image really is.
Derivation
From the Latin latens, meaning 'hidden' or 'lying concealed.' The idea is that the delay is hidden — the data looks current on the screen, but a gap of time is quietly built into it.
Why Pilots Care
High latency means the displayed weather may no longer match actual conditions, affecting route and altitude decisions.
Grounding Statement
A weather image with latency is a delayed picture, not a live window.
Intuition Check
Latency does not mean the radar image is useless or necessarily wrong; it means there is a time lag. Lower latency means more current information, but it still may not be live.
Example Sentence 1
Because of NEXRAD latency, the storm cell on the cockpit display may already have moved several miles from the position shown.
Example Sentence 2
Because of latency, the controller advised checking for newer radar updates before entering the area.