Definition
An unscheduled in-flight weather advisory issued by the Center Weather Service Unit at an Air Route Traffic Control Center (ARTCC). It alerts pilots already airborne to hazardous or potentially hazardous weather conditions — such as severe turbulence, icing, thunderstorms, or low ceilings and visibilities — that may affect flight within that Center's airspace. A CWA is valid for up to two hours and is intended as a nowcast, bridging the gap between scheduled forecasts and rapidly developing conditions.
Plain English
A short-notice weather warning sent out by the controllers' weather unit at a regional air traffic Center, telling pilots in the air about bad or worsening weather happening right now in that area.
Context Anchor
Seen in instrument weather flying, en route weather updates, and ATC communications when hazardous weather such as turbulence may affect a route or altitude.
Derivation
Center' refers to the Air Route Traffic Control Center (ARTCC) — the regional facility that handles aircraft en route between airports. 'Advisory' comes from Latin advisare, meaning 'to consider or give counsel.' So the name simply describes what it is: weather counsel issued by the Center for the airspace it controls.
Why Pilots Care
Allows pilots to anticipate and avoid weather that could cause loss of aircraft control or forced diversions during IFR flight.
Intuition Check
Do not read “Center” as the middle of a storm or airport; here it means an FAA en route air traffic control facility. Do not read “advisory” as something casual or unimportant; it is safety-related weather information, even though it is not a clearance.
Example Sentence 1
While en route, the crew received a CWA warning of severe turbulence below 12,000 feet and requested a climb to smoother air.
Example Sentence 2
A CWA for severe icing led the crew to delay departure until conditions improved.