Plain English Meaning

A short-notice weather warning put out by the weather specialists working inside an Air Traffic Control Center, telling pilots about dangerous weather happening right now or expected within the next couple of hours in that Center's airspace.

Full Definition

An unscheduled in-flight weather advisory issued by the Center Weather Service Unit (CWSU) at an Air Route Traffic Control Center (ARTCC) to alert pilots of existing or anticipated hazardous weather conditions within that Center's airspace. A CWA may be issued as a nowcast describing conditions occurring now, or as a short-term forecast for conditions expected within the next two hours. CWAs are valid for up to two hours and are intended to supplement, not replace, SIGMETs, AIRMETs, and .