Definition
An in-flight weather advisory issued by the National Weather Service to alert pilots of potentially hazardous weather conditions affecting aircraft in flight. The two main types are AIRMETs (WA) and SIGMETs, which describe weather phenomena such as turbulence, icing, mountain obscuration, and reduced visibility that may be hazardous to aircraft, particularly those without de-icing or flight-into-known-icing equipment.
Plain English
A weather warning sent out to pilots while they are flying or planning to fly, telling them about weather that could cause problems — like ice, turbulence, or low visibility.
Context Anchor
Pilots may see WA in aviation weather briefings, flight planning information, or weather updates passed before or during a flight.
Derivation
The letters WA come from the words Weather Advisory. Advisory comes from Latin advisare, meaning 'to consider' or 'to give counsel' — in this case, counsel about weather conditions worth knowing about before or during a flight.
Why Pilots Care
It alerts pilots to conditions like turbulence, icing, or reduced visibility so they can adjust altitude, route, or departure time before encountering problems.
Intuition Check
Do not read advisory as casual advice that can be ignored. In aviation, a Weather Advisory is an official warning-style notice that weather may affect safe flight operations.
Example Sentence 1
Flight Service issued a WA for moderate icing between 6,000 and 12,000 feet along our route, so we filed for 4,000.
Example Sentence 2
Before takeoff the pilot reviewed the current WA to decide whether to climb above the cloud layer.